Les publications

IF du Neurocentre

798 publications

* equal contribution
Les IF indiqués ont été collectés par le Web of Sciences en Juin 2020

12/04/2019 | Science   IF 41
Perspective - Do antidepressants restore lost synapses?
Beyeler A

02/04/2019 | J Clin Invest   IF 12.3
The gliotransmitter ACBP controls feeding and energy homeostasis via the melanocortin system.
Bouyakdan K, Martin H, Lienard F, Budry L, Taib B, Rodaros D, Chretien C, Biron E, Husson Z, Cota D, Penicaud L, Fulton S, Fioramonti X, Alquier T

Glial cells have emerged as key players in the central control of energy balance and etiology of obesity. Astrocytes play a central role in neural communication via the release of gliotransmitters. Acyl-CoA binding protein (ACBP)-derived endozepines are secreted peptides that modulate the GABAA receptor. In the hypothalamus, ACBP is enriched in arcuate nucleus (ARC) astrocytes, ependymocytes and tanycytes. Central administration of the endozepine octadecaneuropeptide (ODN) reduces feeding and improves glucose tolerance, yet the contribution of endogenous ACBP in energy homeostasis is unknown. We demonstrated that ACBP deletion in GFAP+ astrocytes, but not in Nkx2.1-lineage neural cells, promoted diet-induced hyperphagia and obesity in both male and female mice, an effect prevented by viral rescue of ACBP in ARC astrocytes. ACBP-astrocytes were observed in apposition with proopiomelanocortin (POMC) neurons and ODN selectively activated POMC neurons through the ODN-GPCR but not GABAA, and supressed feeding while increasing carbohydrate utilization via the melanocortin system. Similarly, ACBP overexpression in ARC astrocytes reduced feeding and weight gain. Finally, the ODN-GPCR agonist decreased feeding and promoted weight loss in ob/ob mice. These findings uncover ACBP as an ARC gliopeptide playing a key role in energy balance control and exerting strong anorectic effects via the central melanocortin system.

08/03/2019 | Nat Commun   IF 11.9
Deciphering the complex role of thrombospondin-1 in glioblastoma development.
Daubon T, Leon C, Clarke K, Andrique L, Salabert L, Darbo E, Pineau R, Guerit S, Maitre M, Dedieu S, Jeanne A, Bailly S, Feige JJ, Miletic H, Rossi M, Bello L, Falciani F, Bjerkvig R, Bikfalvi A

We undertook a systematic study focused on the matricellular protein Thrombospondin-1 (THBS1) to uncover molecular mechanisms underlying the role of THBS1 in glioblastoma (GBM) development. THBS1 was found to be increased with glioma grades. Mechanistically, we show that the TGFbeta canonical pathway transcriptionally regulates THBS1, through SMAD3 binding to the THBS1 gene promoter. THBS1 silencing inhibits tumour cell invasion and growth, alone and in combination with anti-angiogenic therapy. Specific inhibition of the THBS1/CD47 interaction using an antagonist peptide decreases cell invasion. This is confirmed by CD47 knock-down experiments. RNA sequencing of patient-derived xenograft tissue from laser capture micro-dissected peripheral and central tumour areas demonstrates that THBS1 is one of the gene with the highest connectivity at the tumour borders. All in all, these data show that TGFbeta1 induces THBS1 expression via Smad3 which contributes to the invasive behaviour during GBM expansion. Furthermore, tumour cell-bound CD47 is implicated in this process.

07/03/2019 | JCI Insight   IF 6
The motivation for exercise over palatable food is dictated by cannabinoid type-1 receptors.
Muguruza C, Redon B, Fois GR, Hurel I, Scocard A, Nguyen C, Stevens C, Soria-Gomez E, Varilh M, Cannich A, Daniault J, Busquets-Garcia A, Pelliccia T, Caille S, Georges F, Marsicano G, Chaouloff F

The lack of intrinsic motivation to engage in, and adhere to, physical exercise has major health consequences. However, the neurobiological bases of exercise motivation are still unknown. This study aimed at examining whether the endocannabinoid system (ECS) is involved in this process. To do so, we developed an operant conditioning paradigm wherein mice unlocked a running wheel with nose pokes. Using pharmacological tools and conditional mutants for cannabinoid type-1 (CB1) receptors, we provide evidence that CB1 receptors located on GABAergic neurons are both necessary and sufficient to positively control running motivation. Conversely, this receptor population proved dispensable for the modulation of running duration per rewarded sequence. Although the ECS mediated the motivation for another reward, namely palatable food, such a regulation was independent from CB1 receptors on GABAergic neurons. In addition, we report that the lack of CB1 receptors on GABAergic neurons decreases the preference for running over palatable food when mice were proposed an exclusive choice between the two rewards. Beyond providing a paradigm that enables motivation processes for exercise to be dissected either singly or in concurrence, this study is the first to our knowledge to identify a neurobiological mechanism that might contribute to sedentary behavior.

24/01/2019 | Neurobiol Dis   IF 5.2
Cannabinoid type-1 receptor blockade restores neurological phenotypes in two models for Down syndrome.
Navarro-Romero A, Vazquez-Oliver A, Gomis-Gonzalez M, Garzon-Montesinos C, Falcon-Moya R, Pastor A, Martin-Garcia E, Pizarro N, Busquets-Garcia A, Revest JM, Piazza PV, Bosch F, Dierssen M, de la Torre R, Rodriguez-Moreno A, Maldonado R, Ozaita A

Intellectual disability is the most limiting hallmark of Down syndrome, for which there is no gold-standard clinical treatment yet. The endocannabinoid system is a widespread neuromodulatory system involved in multiple functions including learning and memory processes. Alterations of this system contribute to the pathogenesis of several neurological and neurodevelopmental disorders. However, the involvement of the endocannabinoid system in the pathogenesis of Down syndrome has not been explored before. We used the best-characterized preclinical model of Down syndrome, the segmentally trisomic Ts65Dn model. In male Ts65Dn mice, cannabinoid type-1 receptor (CB1R) expression was enhanced and its function increased in hippocampal excitatory terminals. Knockdown of CB1R in the hippocampus of male Ts65Dn mice restored hippocampal-dependent memory. Concomitant with this result, pharmacological inhibition of CB1R restored memory deficits, hippocampal synaptic plasticity and adult neurogenesis in the subgranular zone of the dentate gyrus. Notably, the blockade of CB1R also normalized hippocampal-dependent memory in female Ts65Dn mice. To further investigate the mechanisms involved, we used a second transgenic mouse model overexpressing a single gene candidate for Down syndrome cognitive phenotypes, the dual specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A). CB1R pharmacological blockade similarly improved cognitive performance, synaptic plasticity and neurogenesis in transgenic male Dyrk1A mice. Our results identify CB1R as a novel druggable target potentially relevant for the improvement of cognitive deficits associated with Down syndrome.

07/01/2019 | Cold Spring Harb Perspect Med   IF 5.6
Development and Patterning of the Cochlea: From Convergent Extension to Planar Polarity.
Montcouquiol M, Kelley MW

Within the mammalian cochlea, sensory hair cells and supporting cells are aligned in curvilinear rows that extend along the length of the tonotopic axis. In addition, all of the cells within the epithelium are uniformly polarized across the orthogonal neural-abneural axis. Finally, each hair cell is intrinsically polarized as revealed by the presence of an asymmetrically shaped and apically localized stereociliary bundle. It has been known for some time that many of the developmental processes that regulate these patterning events are mediated, to some extent, by the core planar cell polarity (PCP) pathway. This article will review more recent work demonstrating how components of the PCP pathway interact with cytoskeletal motor proteins to regulate cochlear outgrowth. Finally, a signaling pathway originally identified for its role in asymmetric cell divisions has recently been shown to mediate several aspects of intrinsic hair cell polarity, including kinocilia migration, bundle shape, and elongation.

2019 | Current Opinion in Behavioral Sciences   IF 3.4
Valence Coding in Amygdala Circuits
Pignatelli M, Beyeler A

The neural mechanisms underlying emotional valence are at the interface between perception and action, integrating inputs from the external environment with past experiences to guide the behavior of an organism. Depending on the positive or negative valence assigned to an environmental stimulus, the organism will approach or avoid the source of the stimulus. Multiple convergent studies have demonstrated that the amygdala complex is a critical node of the circuits assigning valence. Here we examine the current progress in identifying valence coding properties of neural populations in different nuclei of the amygdala, based on their activity, connectivity, and gene expression profile.

2019 | front pharmacol   IF 3.8
Beyond the Activity-Based Anorexia Model: Reinforcing Values of Exercise and Feeding Examined in Stressed Adolescent Male and Female Mice.
Hurel I, Redon B, Scocard A, Malezieux M, Marsicano G, Chaouloff F

Anorexia nervosa (AN), mostly observed in female adolescents, is the most fatal mental illness. Its core is a motivational imbalance between exercise and feeding in favor of the former. The most privileged animal model of AN is the 'activity-based anorexia' (ABA) model wherein partly starved rodents housed with running wheels exercise at the expense of feeding. However, the ABA model bears face and construct validity limits, including its inability to specifically assess running motivation and feeding motivation. As infant/adolescent trauma is a precipitating factor in AN, this study first analyzed post-weaning isolation rearing (PWIR) impacts on body weights and wheel-running performances in female mice exposed to an ABA protocol. Next, we studied through operant conditioning protocols i) whether food restriction affects in a sex-dependent manner running motivation before ii) investigating how PWIR and sex affect running and feeding drives under ad libitum fed conditions and food restriction. Besides amplifying ABA-elicited body weight reductions, PWIR stimulated wheel-running activities in anticipation of feeding in female mice, suggesting increased running motivation. To confirm this hypothesis, we used a cued-reward motivated instrumental task wherein wheel-running was conditioned by prior nose poke responses. It was first observed that food restriction increased running motivation in male, but not female, mice. When fed grouped and PWIR mice were tested for their running and palatable feeding drives, all mice, excepted PWIR males, displayed increased nose poke responses for running over feeding. This was true when rewards were proposed alone or within a concurrent test. The increased preference for running over feeding in fed females did not extend to running performances (time, distance) during each rewarded sequence, confirming that motivation for, and performance during, running are independent entities. With food restriction, mice displayed a sex-independent increase in their preference for feeding over running in both group-housed and PWIR conditions. This study shows that the ABA model does not specifically capture running and feeding drives, i.e. components known to be affected in AN.

2019 | Front Behav Neurosci   IF 2.6
Varenicline Targets the Reinforcing-Enhancing Effect of Nicotine on Its Associated Salient Cue During Nicotine Self-administration in the Rat.
Garcia-Rivas V, Fiancette JF, Cannella N, Carbo-Gas M, Renault P, Tostain J, Deroche-Gamonet V

Nicotine is acknowledged as the key addictive compound of tobacco. Varenicline (Champix((R)) or Chantix((R))), mainly acting as a partial agonist at the alpha4beta2 nicotinic receptor, is an approved smoking cessation pharmacotherapy, although with efficacy limited to a portion of smokers. Smokers differ in the motives that drive their drug seeking and Varenicline might be more efficient in some groups more than others. Studies in rodents revealed that nicotine-seeking is strongly supported by complex interactions between nicotine and environmental cues, and notably the ability of nicotine to enhance the reinforcing properties of salient environmental stimuli. It is not yet understood whether the decrease of nicotine-seeking by acute Varenicline in rats results from antagonism of the primary reinforcing effects of nicotine, of the reinforcement-enhancing effect of nicotine on cues, or of a combination of both. Thanks to a protocol that allows assessment of the reinforcement-enhancing effect of nicotine on cues during self-administration in rats, we showed that Varenicline targets both nicotine reinforcing effects and reinforcement-enhancing effect of nicotine on cues. Importantly, individual variations in the latter determined the amplitude of acute Varenicline-induced decrease in seeking. These results suggest that Varenicline might be more beneficial in smokers who are more sensitive to nicotine effects on surrounding stimuli.

20/12/2018 | j neuroinflammation   IF 5.2
Sequential alteration of microglia and astrocytes in the rat thalamus following spinal nerve ligation.
Blaszczyk L, Maitre M, Leste-Lasserre T, Clark S, Cota D, Oliet SHR, Fenelon VS

BACKGROUND: Spinal reactive astrocytes and microglia are known to participate to the initiation and maintenance of neuropathic pain. However, whether reactive astrocytes and microglia in thalamic nuclei that process sensory-discriminative aspects of pain play a role in pain behavior remains poorly investigated. Therefore, the present study evaluated whether the presence of reactive glia (hypertrophy, increased number and upregulation of glial markers) in the ventral posterolateral thalamic nucleus (VPL) correlates with pain symptoms, 14 and 28 days after unilateral L5/L6 spinal nerve ligation (SNL) in rats. METHODS: Mechanical allodynia and hyperalgesia (von Frey filament stimulation) as well as ambulatory pain (dynamic weight bearing apparatus) were assessed. Levels of nine glial transcripts were determined by quantitative real-time PCR on laser microdissected thalamic nuclei, and levels of proteins were assessed by Western blot. We also studied by immunohistofluorescence the expression of glial markers that label processes (GFAP for astrocytes and iba-1 for microglia) and cell body (S100beta for astrocytes and iba-1 for microglia) and quantified the immunostained surface and the number of astrocytes and microglia (conventional counts and optical dissector method of stereological counting). RESULTS: Differential, time-dependent responses were observed concerning microglia and astrocytes. Specifically, at day 14, iba-1 immunostained area and number of iba-1 immunopositive cells were decreased in the VPL of SNL as compared to naive rats. By contrast, at day 28, GFAP-immunostained area was increased in the VPL of SNL as compared to naive rats while number of GFAP/S100beta immunopositive cells remained unchanged. Using quantitative real-time PCR of laser microdissected VPL, we found a sequential increase in mRNA expression of cathepsin S (day 14), fractalkine (day 28), and fractalkine receptor (day 14), three well-known markers of microglial reactivity. Using Western blot, we confirmed an increase in protein expression of fractalkine receptor at day 14. CONCLUSIONS: Our results demonstrate a sequential alteration of microglia and astrocytes in the thalamus of animals with lesioned peripheral nerves. Furthermore, our data report unprecedented concomitant molecular signs of microglial activation and morphological signs of microglial decline in the thalamus of these animals.

23/11/2018 | Int J Mol Sci   IF 3.7
Heterogeneity in Colorectal Cancer: A Challenge for Personalized Medicine?
Molinari C, Marisi G, Passardi A, Matteucci L, De Maio G, Ulivi P

High inter-patient variability and high spatial heterogeneity are features of colorectal cancer (CRC). This may influence the molecular characterization of tumor tissue, now mandatory for patients with metastatic CRC who are candidates for treatment with an anti-EGFR mAb, as false-negative results can occur, leading to non optimal therapy. Moreover, temporal molecular heterogeneity during treatment is known to influence the response to therapy and prognosis. We present a literature overview of advances made in characterizing molecular heterogeneity in CRC, underlining that the analysis of liquid biopsy could represent an efficient non-invasive tool to overcome the problem. We believe that understanding CRC heterogeneity is fundamental for a more accurate diagnosis, for selecting the best targets to ensure prolonged antitumor response, and for monitoring minimal residual disease and the onset of resistance to therapy, all essential components of successful personalized treatment.

20/11/2018 | ann surg   IF 9.2
Oea Signaling Pathways and the Metabolic Benefits of Vertical Sleeve Gastrectomy.
Hutch CR, Trakimas DR, Roelofs K, Pressler J, Sorrell J, Cota D, Obici S, Sandoval DA

OBJECTIVE: The aim of this study was to determine whether downstream [peroxisome proliferator-activated-receptor alpha (PPARalpha) and the G-protein coupled receptor, GPR119] and upstream (a fatty acid translocase, CD36) signaling targets of N-oleoylethanolamide (OEA) were necessary for weight loss, metabolic improvements, and diet preference following vertical sleeve gastrectomy (VSG). SUMMARY BACKGROUND DATA: OEA is an anorectic N-acylethanolamine produced from dietary fats within the intestinal lumen that can modulate lipid metabolism, insulin secretion, and energy expenditure by activating targets such as PPARalpha and GPR119. METHODS: Diet-induced obese mice, including wild-type or whole body knockout (KO) of PPARalpha, GPR119, and CD36, were stratified to either VSG or sham surgery before body weight, body composition, diet preference, and glucose and lipid metabolic endpoints were assessed. RESULTS: We found increased duodenal production of OEA and expression of both GPR119 and CD36 were upregulated in wild-type mice after VSG. However, weight loss and glucose tolerance were improved in response to VSG in PPARalphaKO, GPR119KO, and CD36KO mice. In fact, VSG corrected hepatic triglyceride dysregulation in CD36KO mice, and circulating triglyceride and cholesterol levels in PPARalphaKO mice. Lastly, we found PPARalpha-mediated signaling contributes to macronutrient preference independent of VSG, while removal of CD36 signaling blunts the VSG-induced shift toward carbohydrate preference. CONCLUSIONS: In the search for more effective and less invasive therapies to help reverse the global acceleration of obesity and obesity-related disease OEA is a promising candidate; however, our data indicate that it is not an underlying mechanism of the effectiveness of VSG.

07/11/2018 | Nature   IF 41.6
Dopamine enhances signal-to-noise ratio in cortical-brainstem encoding of aversive stimuli.
Vander Weele CM, Siciliano CA, Matthews GA, Namburi P, Izadmehr EM, Espinel IC, Nieh EH, Schut EHS, Padilla-Coreano N, Burgos-Robles A, Chang CJ, Kimchi EY, Beyeler A, Wichmann R, Wildes CP, Tye KM

Dopamine modulates medial prefrontal cortex (mPFC) activity to mediate diverse behavioural functions(1,2); however, the precise circuit computations remain unknown. One potentially unifying model by which dopamine may underlie a diversity of functions is by modulating the signal-to-noise ratio in subpopulations of mPFC neurons(3-6), where neural activity conveying sensory information (signal) is amplified relative to spontaneous firing (noise). Here we demonstrate that dopamine increases the signal-to-noise ratio of responses to aversive stimuli in mPFC neurons projecting to the dorsal periaqueductal grey (dPAG). Using an electrochemical approach, we reveal the precise time course of pinch-evoked dopamine release in the mPFC, and show that mPFC dopamine biases behavioural responses to aversive stimuli. Activation of mPFC-dPAG neurons is sufficient to drive place avoidance and defensive behaviours. mPFC-dPAG neurons display robust shock-induced excitations, as visualized by single-cell, projection-defined microendoscopic calcium imaging. Finally, photostimulation of dopamine terminals in the mPFC reveals an increase in the signal-to-noise ratio in mPFC-dPAG responses to aversive stimuli. Together, these data highlight how dopamine in the mPFC can selectively route sensory information to specific downstream circuits, representing a potential circuit mechanism for valence processing.

11/2018 | Mol Psychiatry   IF 11.6
CaMKIIbeta regulates nucleus-centrosome coupling in locomoting neurons of the developing cerebral cortex.
Nicole O, Bell DM, Leste-Lasserre T, Doat H, Guillemot F, Pacary E

11/2018 | Mol Psychiatry   IF 11.6
A novel role for CAMKIIbeta in the regulation of cortical neuron migration: implications for neurodevelopmental disorders.
Nicole O, Bell DM, Leste-Lasserre T, Doat H, Guillemot F, Pacary E

Perturbation of CaMKIIbeta expression has been associated with multiple neuropsychiatric diseases, highlighting CaMKIIbeta as a gene of interest. Yet, in contrast to CaMKIIalpha, the specific functions of CaMKIIbeta in the brain remain poorly explored. Here, we reveal a novel function for this CaMKII isoform in vivo during neuronal development. By using in utero electroporation, we show that CaMKIIbeta is an important regulator of radial migration of projection neurons during cerebral cortex development. Knockdown of CaMKIIbeta causes accelerated migration of nascent pyramidal neurons, whereas overexpression of CaMKIIbeta inhibits migration, demonstrating that precise regulation of CaMKIIbeta expression is required for correct neuronal migration. More precisely, CaMKIIbeta controls the multipolar-bipolar transition in the intermediate zone and locomotion in the cortical plate through its actin-binding and -bundling activities. In addition, our data indicate that a fine-tuned balance between CaMKIIbeta and cofilin activities is necessary to ensure proper migration of cortical neurons. Thus, our findings define a novel isoform-specific function for CaMKIIbeta, demonstrating that CaMKIIbeta has a major biological function in the developing brain.

16/10/2018 | Acta Neuropathol Commun   IF 5.4
Modulation of astrocyte reactivity improves functional deficits in mouse models of Alzheimer's disease.
Ceyzeriat K, Ben Haim L, Denizot A, Pommier D, Matos M, Guillemaud O, Palomares MA, Abjean L, Petit F, Gipchtein P, Gaillard MC, Guillermier M, Bernier S, Gaudin M, Auregan G, Josephine C, Dechamps N, Veran J, Langlais V, Cambon K, Bemelmans AP, Baijer J, Bonvento G, Dhenain M, Deleuze JF, Oliet SHR, Brouillet E, Hantraye P, Carrillo-de Sauvage MA, Olaso R, Panatier A, Escartin C

Astrocyte reactivity and neuroinflammation are hallmarks of CNS pathological conditions such as Alzheimer's disease. However, the specific role of reactive astrocytes is still debated. This controversy may stem from the fact that most strategies used to modulate astrocyte reactivity and explore its contribution to disease outcomes have only limited specificity. Moreover, reactive astrocytes are now emerging as heterogeneous cells and all types of astrocyte reactivity may not be controlled efficiently by such strategies.Here, we used cell type-specific approaches in vivo and identified the JAK2-STAT3 pathway, as necessary and sufficient for the induction and maintenance of astrocyte reactivity. Modulation of this cascade by viral gene transfer in mouse astrocytes efficiently controlled several morphological and molecular features of reactivity. Inhibition of this pathway in mouse models of Alzheimer's disease improved three key pathological hallmarks by reducing amyloid deposition, improving spatial learning and restoring synaptic deficits.In conclusion, the JAK2-STAT3 cascade operates as a master regulator of astrocyte reactivity in vivo. Its inhibition offers new therapeutic opportunities for Alzheimer's disease.

10/2018 | Curr Opin Neurobiol   IF 6.5
Neuronal coding mechanisms mediating fear behavior.
Rozeske RR, Herry C

The behavioral repertoire of an organism can be highly diverse, spanning from social to defensive. How an animal efficiently switches between distinct behaviors is a fundamental question whose inquiry will provide insights into the mechanisms that are necessary for an organism's survival. Previous work aimed at identifying the neural systems responsible for defensive behaviors, such as freezing, has demonstrated critical interactions between the prefrontal cortex and amygdala. Indeed, this foundational research has provided an indispensable anatomical framework that investigators are now using to understand the physiological mechanisms of defined neural circuits within the prefrontal cortex that code for the rapid and flexible expression of defensive behaviors. Here we review recent findings demonstrating temporal and rate coding mechanisms of freezing behavior in the prefrontal cortex. We hypothesize that anatomical features, such as target structure and cortical layer, as well as the nature of the information to be coded, may be critical factors determining the coding scheme. Furthermore, detailed behavioral analyses may reveal subtypes of defensive behaviors that represent the principle factor governing coding selection.

23/09/2018 | Exp Neurol   IF 4.5
Serotonin2B receptors in the rat dorsal raphe nucleus exert a GABA-mediated tonic inhibitory control on serotonin neurons.
Cathala A, Devroye C, Drutel G, Revest JM, Artigas F, Spampinato U

The central serotonin2B receptor (5-HT2BR) is a well-established modulator of dopamine (DA) neuron activity in the rodent brain. Recent studies in rats have shown that the effect of 5-HT2BR antagonists on accumbal and medial prefrontal cortex (mPFC) DA outflow results from a primary action in the dorsal raphe nucleus (DRN), where they activate 5-HT neurons innervating the mPFC. Although the mechanisms underlying this interaction remain largely unknown, data in the literature suggest the involvement of DRN GABAergic interneurons in the control of 5-HT activity. The present study examined this hypothesis using in vivo (intracerebral microdialysis) and in vitro (immunohistochemistry coupled to reverse transcription-polymerase chain reaction) experimental approaches in rats. Intraperitoneal (0.16mg/kg) or intra-DRN (1muM) administration of the selective 5-HT2BR antagonist RS 127445 increased 5-HT outflow in both the DRN and the mPFC, these effects being prevented by the intra-DRN perfusion of the GABAA antagonist bicuculline (100muM), as well as by the subcutaneous (0.16mg/kg) or the intra-DRN (0.1muM) administration of the selective 5-HT1AR antagonist WAY 100635. The increase in DRN 5-HT outflow induced by the intra-DRN administration of the selective 5-HT reuptake inhibitor citalopram (0.1muM) was potentiated by the intra-DRN administration (0.5muM) of RS 127445 only in the absence of bicuculline perfusion. Finally, in vitro experiments revealed the presence of the 5-HT2BR mRNA on DRN GABAergic interneurons. Altogether, these results show that, in the rat DRN, 5-HT2BRs are located on GABAergic interneurons, and exert a tonic inhibitory control on 5-HT neurons innervating the mPFC.

In nonhuman mammals and in particular in rodents, most granule neurons of the dentate gyrus (DG) are generated during development and yet little is known about their properties compared with adult-born neurons. Although it is generally admitted that these populations are morphologically indistinguishable once mature, a detailed analysis of developmentally born neurons is lacking. Here, we used in vivo electroporation to label dentate granule cells (DGCs) generated in mouse embryos (E14.5) or in neonates (P0) and followed their morphological development up to 6 months after birth. By comparison with mature retrovirus-labeled DGCs born at weaning (P21) or young adult (P84) stages, we provide the evidence that perinatally born neurons, especially embryonically born cells, are morphologically distinct from later-born neurons and are thus easily distinguishable. In addition, our data indicate that semilunar and hilar GCs, 2 populations in ectopic location, are generated during the embryonic and the neonatal periods, respectively. Thus, our findings provide new insights into the development of the different populations of GCs in the DG and open new questions regarding their function in the brain.

23/08/2018 | Neuron   IF 14.3
Hippocampal CB1 Receptors Control Incidental Associations.
Busquets-Garcia A, Oliveira da Cruz JF, Terral G, Zottola ACP, Soria-Gomez E, Contini A, Martin H, Redon B, Varilh M, Ioannidou C, Drago F, Massa F, Fioramonti X, Trifilieff P, Ferreira G, Marsicano G

By priming brain circuits, associations between low-salience stimuli often guide future behavioral choices through a process known as mediated or inferred learning. However, the precise neurobiological mechanisms of these incidental associations are largely unknown. Using sensory preconditioning procedures, we show that type 1 cannabinoid receptors (CB1R) in hippocampal GABAergic neurons are necessary and sufficient for mediated but not direct learning. Deletion and re-expression of CB1R in hippocampal GABAergic neurons abolishes and rescues mediated learning, respectively. Interestingly, paired presentations of low-salience sensory cues induce a specific protein synthesis-dependent enhancement of hippocampal CB1R expression and facilitate long-term synaptic plasticity at inhibitory synapses. CB1R blockade or chemogenetic manipulations of hippocampal GABAergic neurons upon preconditioning affect incidental associations, as revealed by impaired mediated learning. Thus, CB1R-dependent control of inhibitory hippocampal neurotransmission mediates incidental associations, allowing future associative inference, a fundamental process for everyday life, which is altered in major neuropsychiatric diseases.

09/07/2018 | Sci Rep   IF 4.1
Shifts of Faecal Microbiota During Sporadic Colorectal Carcinogenesis.
Mori G, Rampelli S, Orena BS, Rengucci C, De Maio G, Barbieri G, Passardi A, Casadei Gardini A, Frassineti GL, Gaiarsa S, Albertini AM, Ranzani GN, Calistri D, Pasca MR

Gut microbiota has been implicated in the etiopathogenesis of colorectal cancer. The development of colorectal cancer is a multistep process by which healthy epithelium slowly develops into preneoplastic lesions, which in turn progress into malignant carcinomas over time. In particular, sporadic colorectal cancers can arise from adenomas (about 85% of cases) or serrated polyps through the 'adenoma-carcinoma' or the 'serrated polyp-carcinoma' sequences, respectively. In this study, we performed 16 S rRNA gene sequencing of bacterial DNA extracted from faecal samples to compare the microbiota of healthy subjects and patients with different preneoplastic and neoplastic lesions. We identified putative microbial biomarkers associated with stage-specific progression of colorectal cancer. In particular, bacteria belonging to the Firmicutes and Actinobacteria phyla, as well as members of the Lachnospiraceae family, proved to be specific of the faecal microbiota of patients with preneoplastic lesions, including adenomas and hyperplastic polyps. On the other hand, two families of the Proteobacteria phylum, Alcaligeneaceae and Enterobacteriaceae, with Sutterella and Escherichia/Shigella being the most representative genera, appeared to be associated with malignancy. These findings, once confirmed on larger cohorts of patients, can represent an important step towards the development of more effective diagnostic strategies.

21/06/2018 | cell physiol biochem   IF 5.5
Galphai Proteins are Indispensable for Hearing.
Beer-Hammer S, Lee SC, Mauriac SA, Leiss V, Groh IAM, Novakovic A, Piekorz RP, Bucher K, Chen C, Ni K, Singer W, Harasztosi C, Schimmang T, Zimmermann U, Pfeffer K, Birnbaumer L, Forge A, Montcouquiol M, Knipper M, Nurnberg B, Ruttiger L

BACKGROUND/AIMS: From invertebrates to mammals, Galphai proteins act together with their common binding partner Gpsm2 to govern cell polarization and planar organization in virtually any polarized cell. Recently, we demonstrated that Galphai3-deficiency in pre-hearing murine cochleae pointed to a role of Galphai3 for asymmetric migration of the kinocilium as well as the orientation and shape of the stereociliary ('hair') bundle, a requirement for the progression of mature hearing. We found that the lack of Galphai3 impairs stereociliary elongation and hair bundle shape in high-frequency cochlear regions, linked to elevated hearing thresholds for high-frequency sound. How these morphological defects translate into hearing phenotypes is not clear. METHODS: Here, we studied global and conditional Gnai3 and Gnai2 mouse mutants deficient for either one or both Galphai proteins. Comparative analyses of global versus Foxg1-driven conditional mutants that mainly delete in the inner ear and telencephalon in combination with functional tests were applied to dissect essential and redundant functions of different Galphai isoforms and to assign specific defects to outer or inner hair cells, the auditory nerve, satellite cells or central auditory neurons. RESULTS: Here we report that lack of Galphai3 but not of the ubiquitously expressed Galphai2 elevates hearing threshold, accompanied by impaired hair bundle elongation and shape in high-frequency cochlear regions. During the crucial reprogramming of the immature inner hair cell (IHC) synapse into a functional sensory synapse of the mature IHC deficiency for Galphai2 or Galphai3 had no impact. In contrast, double-deficiency for Galphai2 and Galphai3 isoforms results in abnormalities along the entire tonotopic axis including profound deafness associated with stereocilia defects. In these mice, postnatal IHC synapse maturation is also impaired. In addition, the analysis of conditional versus global Galphai3-deficient mice revealed that the amplitude of ABR wave IV was disproportionally elevated in comparison to ABR wave I indicating that Galphai3 is selectively involved in generation of neural gain during auditory processing. CONCLUSION: We propose a so far unrecognized complexity of isoform-specific and overlapping Galphai protein functions particular during final differentiation processes.

20/06/2018 | bio protoc
Protocols to Study Declarative Memory Formation in Mice and Humans: Optogenetics and Translational Behavioral Approaches
Sellami A, Al abed S, Brayda-Bruno L, Etchamendy N, Valerio S, Oule M, Pantaleon L, Lamothe V, Potier M, Bernard K, Jabourian M, Herry C, Mons N, Marighetto A

11/06/2018 | Sci Rep   IF 4.1
D5 dopamine receptors control glutamatergic AMPA transmission between the motor cortex and subthalamic nucleus.
Froux L, Le Bon-Jego M, Miguelez C, Normand E, Morin S, Fioramonti S, Barresi M, Frick A, Baufreton J, Taupignon A

Corticofugal fibers target the subthalamic nucleus (STN), a component nucleus of the basal ganglia, in addition to the striatum, their main input. The cortico-subthalamic, or hyperdirect, pathway, is thought to supplement the cortico-striatal pathways in order to interrupt/change planned actions. To explore the previously unknown properties of the neurons that project to the STN, retrograde and anterograde tools were used to specifically identify them in the motor cortex and selectively stimulate their synapses in the STN. The cortico-subthalamic neurons exhibited very little sag and fired an initial doublet followed by non-adapting action potentials. In the STN, AMPA/kainate synaptic currents had a voltage-dependent conductance, indicative of GluA2-lacking receptors and were partly inhibited by Naspm. AMPA transmission displayed short-term depression, with the exception of a limited bandpass in the 5 to 15 Hz range. AMPA synaptic currents were negatively controlled by dopamine D5 receptors. The reduction in synaptic strength was due to postsynaptic D5 receptors, mediated by a PKA-dependent pathway, but did not involve a modified rectification index. Our data indicated that dopamine, through post-synaptic D5 receptors, limited the cortical drive onto STN neurons in the normal brain.

06/06/2018 | Neuron   IF 14.3
Astroglial CB1 Receptors Determine Synaptic D-Serine Availability to Enable Recognition Memory.
Robin LM*, Cruz J*, Oliveira da Cruz JF, Langlais VC, Martin-Fernandez M, Metna-Laurent M, Busquets-Garcia A, Bellocchio L, Soria-Gomez E, Papouin T, Varilh M, Sherwood MW, Belluomo I, Balcells G, Matias I, Bosier B, Drago F, Van Eeckhaut A, Smolders I, Georges F, Araque A, Panatier A, Oliet SHR*, Marsicano G*

Bidirectional communication between neurons and astrocytes shapes synaptic plasticity and behavior. D-serine is a necessary co-agonist of synaptic N-methyl-D-aspartate receptors (NMDARs), but the physiological factors regulating its impact on memory processes are scantly known. We show that astroglial CB1 receptors are key determinants of object recognition memory by determining the availability of D-serine at hippocampal synapses. Mutant mice lacking CB1 receptors from astroglial cells (GFAP-CB1-KO) displayed impaired object recognition memory and decreased in vivo and in vitro long-term potentiation (LTP) at CA3-CA1 hippocampal synapses. Activation of CB1 receptors increased intracellular astroglial Ca(2+) levels and extracellular levels of D-serine in hippocampal slices. Accordingly, GFAP-CB1-KO displayed lower occupancy of the co-agonist binding site of synaptic hippocampal NMDARs. Finally, elevation of D-serine levels fully rescued LTP and memory impairments of GFAP-CB1-KO mice. These data reveal a novel mechanism of in vivo astroglial control of memory and synaptic plasticity via the D-serine-dependent control of NMDARs.

31/05/2018 | Cell   IF 31.4
Corticoamygdala Transfer of Socially Derived Information Gates Observational Learning.
Allsop SA, Wichmann R, Mills F, Burgos-Robles A, Chang CJ, Felix-Ortiz AC, Vienne A, Beyeler A, Izadmehr EM, Glober G, Cum MI, Stergiadou J, Anandalingam KK, Farris K, Namburi P, Leppla CA, Weddington JC, Nieh EH, Smith AC, Ba D, Brown EN, Tye KM

Observational learning is a powerful survival tool allowing individuals to learn about threat-predictive stimuli without directly experiencing the pairing of the predictive cue and punishment. This ability has been linked to the anterior cingulate cortex (ACC) and the basolateral amygdala (BLA). To investigate how information is encoded and transmitted through this circuit, we performed electrophysiological recordings in mice observing a demonstrator mouse undergo associative fear conditioning and found that BLA-projecting ACC (ACC-->BLA) neurons preferentially encode socially derived aversive cue information. Inhibition of ACC-->BLA alters real-time amygdala representation of the aversive cue during observational conditioning. Selective inhibition of the ACC-->BLA projection impaired acquisition, but not expression, of observational fear conditioning. We show that information derived from observation about the aversive value of the cue is transmitted from the ACC to the BLA and that this routing of information is critically instructive for observational fear conditioning. VIDEO ABSTRACT.

25/05/2018 | Nat Commun   IF 12.4
Author Correction: Defective Gpsm2/Galphai3 signalling disrupts stereocilia development and growth cone actin dynamics in Chudley-McCullough syndrome.
Mauriac SA, Hien YE, Bird JE, Carvalho SD, Peyroutou R, Lee SC, Moreau MM, Blanc JM, Gezer A, Medina C, Thoumine O, Beer-Hammer S, Friedman TB, Ruttiger L, Forge A, Nurnberg B, Sans N, Montcouquiol M

This corrects the article DOI: 10.1038/ncomms14907.

23/05/2018 | Nat Commun   IF 12.4
Combining laser capture microdissection and proteomics reveals an active translation machinery controlling invadosome formation.
Ezzoukhry Z, Henriet E, Cordelieres FP, Dupuy JW, Maitre M, Gay N, Di-Tommaso S, Mercier L, Goetz JG, Peter M, Bard F, Moreau V, Raymond AA, Saltel F

Invadosomes are F-actin-based structures involved in extracellular matrix degradation, cell invasion, and metastasis formation. Analyzing their proteome is crucial to decipher their molecular composition, to understand their mechanisms, and to find specific elements to target them. However, the specific analysis of invadosomes is challenging, because it is difficult to maintain their integrity during isolation. In addition, classical purification methods often suffer from contaminations, which may impair data validation. To ensure the specific identification of invadosome components, we here develop a method that combines laser microdissection and mass spectrometry, enabling the analysis of subcellular structures in their native state based on low amounts of input material. Using this combinatorial method, we show that invadosomes contain specific components of the translational machinery, in addition to known marker proteins. Moreover, functional validation reveals that protein translation activity is an inherent property of invadosomes, which is required to maintain invadosome structure and activity.

18/04/2018 | Cereb Cortex   IF 6.3
Dysfunctional Autism Risk Genes Cause Circuit-Specific Connectivity Deficits With Distinct Developmental Trajectories
Zerbi Valerio, Giovanna D. Ielacqua, Marija Markicevic, Matthias Georg Haberl, Mark H. Ellisman, A-Bhaskaran A, Frick A, Markus Rudin, Nicole Wenderoth

Autism spectrum disorders (ASD) are a set of complex neurodevelopmental disorders for which there is currently no targeted therapeutic approach. It is thought that alterations of genes regulating migration and synapse formation during development affect neural circuit formation and result in aberrant connectivity within distinct circuits that underlie abnormal behaviors. However, it is unknown whether deviant developmental trajectories are circuit-specific for a given autism risk-gene. We used MRI to probe changes in functional and structural connectivity from childhood to adulthood in Fragile-X (Fmr1−/y) and contactin-associated (CNTNAP2−/−) knockout mice. Young Fmr1−/y mice (30 days postnatal) presented with a robust hypoconnectivity phenotype in corticocortico and corticostriatal circuits in areas associated with sensory information processing, which was maintained until adulthood. Conversely, only small differences in hippocampal and striatal areas were present during early postnatal development in CNTNAP2−/− mice, while major connectivity deficits in prefrontal and limbic pathways developed between adolescence and adulthood. These findings are supported by viral tracing and electron micrograph approaches and define 2 clearly distinct connectivity endophenotypes within the autism spectrum. We conclude that the genetic background of ASD strongly influences which circuits are most affected, the nature of the phenotype, and the developmental time course of the associated changes.

18/04/2018 | cell stem cell   IF 23.3
Human Adult Neurogenesis: Evidence and Remaining Questions.
Kempermann G, Gage FH, Aigner L, Song H, Curtis MA, Thuret S, Kuhn HG, Jessberger S, Frankland PW, Cameron HA, Gould E, Hen R, Abrous DN, Toni N, Schinder AF, Zhao X, Lucassen PJ, Frisen J

Renewed discussion about whether or not adult neurogenesis exists in the human hippocampus, and the nature and strength of the supporting evidence, has been reignited by two prominently published reports with opposite conclusions. Here, we summarize the state of the field and argue that there is currently no reason to abandon the idea that adult-generated neurons make important functional contributions to neural plasticity and cognition across the human lifespan.

13/04/2018 | Mol Metab   IF 6.3
mTORC1-dependent increase in oxidative metabolism in POMC neurons regulates food intake and action of leptin.
Haissaguerre M, Ferriere A, Simon V, Saucisse N, Dupuy N, Andre C, Clark S, Guzman-Quevedo O, Tabarin A, Cota D

OBJECTIVE: Nutrient availability modulates reactive oxygen species (ROS) production in the hypothalamus. In turn, ROS regulate hypothalamic neuronal activity and feeding behavior. The mechanistic target of rapamycin complex 1 (mTORC1) pathway is an important cellular integrator of the action of nutrients and hormones. Here we tested the hypothesis that modulation of mTORC1 activity, particularly in Proopiomelanocortin (POMC)-expressing neurons, mediates the cellular and behavioral effects of ROS. METHODS: C57BL/6J mice or controls and their knockout (KO) littermates deficient either for the mTORC1 downstream target 70-kDa ribosomal protein S6 kinase 1 (S6K1) or for the mTORC1 component Rptor specifically in POMC neurons (POMC-rptor-KO) were treated with an intracerebroventricular (icv) injection of the ROS hydrogen peroxide (H2O2) or the ROS scavenger honokiol, alone or, respectively, in combination with the mTORC1 inhibitor rapamycin or the mTORC1 activator leptin. Oxidant-related signal in POMC neurons was assessed using dihydroethidium (DHE) fluorescence. RESULTS: Icv administration of H2O2 decreased food intake, while co-administration of rapamycin, whole-body deletion of S6K1, or deletion of rptor in POMC neurons impeded the anorectic action of H2O2. H2O2 also increased oxidant levels in POMC neurons, an effect that hinged on functional mTORC1 in these neurons. Finally, scavenging ROS prevented the hypophagic action of leptin, which in turn required mTORC1 to increase oxidant levels in POMC neurons and to inhibit food intake. CONCLUSIONS: Our results demonstrate that ROS and leptin require mTORC1 pathway activity in POMC neurons to increase oxidant levels in POMC neurons and consequently decrease food intake.

13/03/2018 | Brain Behav Immun   IF 6.3
mTORC1 pathway disruption abrogates the effects of the ciliary neurotrophic factor on energy balance and hypothalamic neuroinflammation.
Andre C, Catania C, Remus-Borel J, Ladeveze E, Leste-Lasserre T, Mazier W, Binder E, Gonzales D, Clark S, Guzman-Quevedo O, Abrous DN, Laye S, Cota D

Ciliary neurotrophic factor (CNTF) potently decreases food intake and body weight in diet-induced obese mice by acting through neuronal circuits and pathways located in the arcuate nucleus (ARC) of the hypothalamus. CNTF also exerts pro-inflammatory actions within the brain. Here we tested whether CNTF modifies energy balance by inducing inflammatory responses in the ARC and whether these effects depend upon the mechanistic target of rapamycin complex 1 (mTORC1) pathway, which regulates both energy metabolism and inflammation. To this purpose, chow- and high fat diet (HFD)- fed mice lacking the S6 kinase 1 (S6K1(-/-)), a downstream target of mTORC1, and their wild-type (WT) littermates received 12 days continuous intracerebroventricular (icv) infusion of the CNTF analogue axokine (CNTFAx15). Behavioral, metabolic and molecular effects were evaluated. Central chronic administration of CNTFAx15 decreased body weight and feed efficiency in WT mice only, when fed HFD, but not chow. These metabolic effects correlated with increased number of iba-1 positive microglia specifically in the ARC and were accompanied by significant increases of IL-1beta and TNF-alpha mRNA expression in the hypothalamus. Hypothalamic iNOS and SOCS3 mRNA, molecular markers of pro-inflammatory response, were also increased by CNTFAx15. All these changes were absent in S6K1(-/-) mice. This study reveals that CNTFAx15 requires a functional S6K1 to modulate energy balance and hypothalamic inflammation in a diet-dependent fashion. Further investigations should determine whether S6K1 is a suitable target for the treatment of pathologies characterized by a high neuroinflammatory state.

06/03/2018 | Cell Rep   IF 8
Transcriptional Dysregulation in Postnatal Glutamatergic Progenitors Contributes to Closure of the Cortical Neurogenic Period.
Donega V, Marcy G, Lo Giudice Q, Zweifel S, Angonin D, Fiorelli R, Abrous DN, Rival-Gervier S, Koehl M, Jabaudon D, Raineteau O

Progenitors of cortical glutamatergic neurons (Glu progenitors) are usually thought to switch fate before birth to produce astrocytes. We used fate-mapping approaches to show that a large fraction of Glu progenitors persist in the postnatal forebrain after closure of the cortical neurogenesis period. Postnatal Glu progenitors do not accumulate during embryonal development but are produced by embryonal radial glial cells that persist after birth in the dorsal subventricular zone and continue to give rise to cortical neurons, although with low efficiency. Single-cell RNA sequencing reveals a dysregulation of transcriptional programs, which parallels changes in m(6)A methylation and correlates with the gradual decline in cortical neurogenesis observed in vivo. Rescuing experiments show that postnatal progenitors are partially permissive to genetic and pharmacological manipulations. Our study provides an in-depth characterization of postnatal Glu progenitors and identifies potential therapeutic targets for promoting brain repair.

05/03/2018 | Nat Neurosci   IF 19.9
Nontoxic, double-deletion-mutant rabies viral vectors for retrograde targeting of projection neurons.
Chatterjee S, Sullivan HA, MacLennan BJ, Xu R, Hou Y, Lavin TK, Lea NE, Michalski JE, Babcock KR, Dietrich S, Matthews GA, Beyeler A, Calhoon GG, Glober G, Whitesell JD, Yao S, Cetin A, Harris JA, Zeng H, Tye KM, Reid RC, Wickersham IR

Recombinant rabies viral vectors have proven useful for applications including retrograde targeting of projection neurons and monosynaptic tracing, but their cytotoxicity has limited their use to short-term experiments. Here we introduce a new class of double-deletion-mutant rabies viral vectors that left transduced cells alive and healthy indefinitely. Deletion of the viral polymerase gene abolished cytotoxicity and reduced transgene expression to trace levels but left vectors still able to retrogradely infect projection neurons and express recombinases, allowing downstream expression of other transgene products such as fluorophores and calcium indicators. The morphology of retrogradely targeted cells appeared unperturbed at 1 year postinjection. Whole-cell patch-clamp recordings showed no physiological abnormalities at 8 weeks. Longitudinal two-photon structural and functional imaging in vivo, tracking thousands of individual neurons for up to 4 months, showed that transduced neurons did not die but retained stable visual response properties even at the longest time points imaged.

05/03/2018 | Mol Psychiatry   IF 11.6
Depleting adult dentate gyrus neurogenesis increases cocaine-seeking behavior.
Deroche-Gamonet V, Revest JM, Fiancette JF, Balado E, Koehl M, Grosjean N, Abrous DN, Piazza PV

The hippocampus is the main locus for adult dentate gyrus (DG) neurogenesis. A number of studies have shown that aberrant DG neurogenesis correlates with many neuropsychiatric disorders, including drug addiction. Although clear causal relationships have been established between DG neurogenesis and memory dysfunction or mood-related disorders, evidence of the causal role of DG neurogenesis in drug-seeking behaviors has not been established. Here we assessed the role of new DG neurons in cocaine self-administration using an inducible transgenic approach that selectively depletes adult DG neurogenesis. Our results show that transgenic mice with decreased adult DG neurogenesis exhibit increased motivation to self-administer cocaine and a higher seeking response to cocaine-related cues. These results identify adult hippocampal neurogenesis as a key factor in vulnerability to cocaine addiction.

02/03/2018 | Sci Rep   IF 4.1
Metabolic Reprogramming in Amyotrophic Lateral Sclerosis.
Szelechowski M, Amoedo N, Obre E, Leger C, Allard L, Bonneu M, Claverol S, Lacombe D, Oliet S, Chevallier S, Le Masson G, Rossignol R

Mitochondrial dysfunction in the spinal cord is a hallmark of amyotrophic lateral sclerosis (ALS), but the neurometabolic alterations during early stages of the disease remain unknown. Here, we investigated the bioenergetic and proteomic changes in ALS mouse motor neurons and patients' skin fibroblasts. We first observed that SODG93A mice presymptomatic motor neurons display alterations in the coupling efficiency of oxidative phosphorylation, along with fragmentation of the mitochondrial network. The proteome of presymptomatic ALS mice motor neurons also revealed a peculiar metabolic signature with upregulation of most energy-transducing enzymes, including the fatty acid oxidation (FAO) and the ketogenic components HADHA and ACAT2, respectively. Accordingly, FAO inhibition altered cell viability specifically in ALS mice motor neurons, while uncoupling protein 2 (UCP2) inhibition recovered cellular ATP levels and mitochondrial network morphology. These findings suggest a novel hypothesis of ALS bioenergetics linking FAO and UCP2. Lastly, we provide a unique set of data comparing the molecular alterations found in human ALS patients' skin fibroblasts and SODG93A mouse motor neurons, revealing conserved changes in protein translation, folding and assembly, tRNA aminoacylation and cell adhesion processes.

Tobacco use leads to 6 million deaths every year due to severe long-lasting diseases. The main component of tobacco, nicotine, is recognized as one of the most addictive drugs, making smoking cessation difficult, even when 70 percent of smokers wish to do so. Clinical and preclinical studies have demonstrated consistently that nicotine seeking is a complex behavior involving various psychopharmacological mechanisms. Evidence supports that the population of smokers is heterogeneous, particularly as regards the breadth of motives that determine the urge to smoke. Here, we review converging psychological, genetic and neurobiological data from clinical and preclinical studies supporting that the mechanisms controlling nicotine seeking may vary from individual to individual. It appears timely that basic neuroscience integrates this heterogeneity to refine our understanding of the neurobiology of nicotine seeking, as tremendous progress has been made in modeling the various psychopharmacological mechanisms driving nicotine seeking in rodents. For a better understanding of the mechanisms that drive nicotine seeking, we emphasize the need for individual-based research strategies in which nicotine seeking, and eventually treatment efficacy, are determined while taking into account individual variations in the mechanisms of nicotine seeking.

26/02/2018 | Glia   IF 5.8
Localization of the cannabinoid type-1 receptor in subcellular astrocyte compartments of mutant mouse hippocampus.
Gutierrez-Rodriguez A, Bonilla-Del Rio I, Puente N, Gomez-Urquijo SM, Fontaine CJ, Egana-Huguet J, Elezgarai I, Ruehle S, Lutz B, Robin LM, Soria-Gomez E, Bellocchio L, Padwal JD, van der Stelt M, Mendizabal-Zubiaga J, Reguero L, Ramos A, Gerrikagoitia I, Marsicano G, Grandes P

Astroglial type-1 cannabinoid (CB1 ) receptors are involved in synaptic transmission, plasticity and behavior by interfering with the so-called tripartite synapse formed by pre- and post-synaptic neuronal elements and surrounding astrocyte processes. However, little is known concerning the subcellular distribution of astroglial CB1 receptors. In particular, brain CB1 receptors are mostly localized at cells' plasmalemma, but recent evidence indicates their functional presence in mitochondrial membranes. Whether CB1 receptors are present in astroglial mitochondria has remained unknown. To investigate this issue, we included conditional knock-out mice lacking astroglial CB1 receptor expression specifically in glial fibrillary acidic protein (GFAP)-containing astrocytes (GFAP-CB1 -KO mice) and also generated genetic rescue mice to re-express CB1 receptors exclusively in astrocytes (GFAP-CB1 -RS). To better identify astroglial structures by immunoelectron microscopy, global CB1 knock-out (CB1 -KO) mice and wild-type (CB1 -WT) littermates were intra-hippocampally injected with an adeno-associated virus expressing humanized renilla green fluorescent protein (hrGFP) under the control of human GFAP promoter to generate GFAPhrGFP-CB1 -KO and -WT mice, respectively. Furthermore, double immunogold (for CB1 ) and immunoperoxidase (for GFAP or hrGFP) revealed that CB1 receptors are present in astroglial mitochondria from different hippocampal regions of CB1 -WT, GFAP-CB1 -RS and GFAPhrGFP-CB1 -WT mice. Only non-specific gold particles were detected in mouse hippocampi lacking CB1 receptors. Altogether, we demonstrated the existence of a precise molecular architecture of the CB1 receptor in astrocytes that will have to be taken into account in evaluating the functional activity of cannabinergic signaling at the tripartite synapse.

30/01/2018 | Neuroimage   IF 5.4
Deciphering the microstructure of hippocampal subfields with in vivo DTI and NODDI: Applications to experimental multiple sclerosis.
Crombe A, Planche V, Raffard G, Bourel J, Dubourdieu N, Panatier A, Fukutomi H, Dousset V, Oliet S, Hiba B, Tourdias T

The hippocampus contains distinct populations of neurons organized into separate anatomical subfields and layers with differential vulnerability to pathological mechanisms. The ability of in vivo neuroimaging to pinpoint regional vulnerability is especially important for better understanding of hippocampal pathology at the early stage of neurodegenerative disorders and for monitoring future therapeutic strategies. This is the case for instance in multiple sclerosis whose neurodegenerative component can affect the hippocampus from the early stage. We challenged the capacity of two models, i.e. the classical diffusion tensor imaging (DTI) model and the neurite orientation dispersion and density imaging (NODDI) model, to compute quantitative diffusion MRI that could capture microstructural alterations in the individual hippocampal layers of experimental-autoimmune encephalomyelitis (EAE) mice, the animal model of multiple sclerosis. To achieve this, the hippocampal anatomy of a healthy mouse brain was first explored ex vivo with high resolution DTI and NODDI. Then, 18 EAE mice and 18 control mice were explored 20 days after immunization with in vivo diffusion MRI prior to sacrifice for the histological quantification of neurites and glial markers in each hippocampal layer. Fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD) maps were computed from the DTI model while the orientation dispersion index (ODI), the neurite density index (NDI) and the volume fraction of isotropic diffusivity (isoVF) maps were computed from the NODDI model. We first showed in control mice that color-coded FA and ODI maps can delineate three main hippocampal layers. The quantification of FA, AD, RD, MD, ODI, NDI and isoVF presented differences within these 3 layers, especially within the molecular layer of the dentate gyrus which displayed a specific signature based on a combination of AD (or MD), ODI and NDI. Then, the comparison between EAE and control mice showed a decrease of AD (p=0.036) and of MD (p=0.033) selectively within the molecular layer of EAE mice while NODDI indices did not present any difference between EAE and control mice in any layer. Histological analyses confirmed the differential vulnerability of the molecular layer of EAE mice that exhibited decreased dendritic length and decreased dendritic complexity together with activated microglia. Dendritic length and intersections within the molecular layer were independent contributors to the observed decrease of AD (R(2)=0.37 and R(2)=0.40, p<0.0001) and MD (R(2)=0.41 and R(2)=0.42, p<0.0001). We therefore identified that NODDI maps can help to highlight the internal microanatomy of the hippocampus but NODDI still presents limitations in grey matter as it failed to capture selective dendritic alterations occurring at early stages of a neurodegenerative disease such as multiple sclerosis, whereas DTI maps were significantly altered.

24/01/2018 | Neuron   IF 14.3
Prefrontal-Periaqueductal Gray-Projecting Neurons Mediate Context Fear Discrimination.
Rozeske RR, Jercog D, Karalis N, Chaudun F, Khoder S, Girard D, Winke N, Herry C

Survival critically depends on selecting appropriate defensive or exploratory behaviors and is strongly influenced by the surrounding environment. Contextual discrimination is a fundamental process that is thought to depend on the prefrontal cortex to integrate sensory information from the environment and regulate adaptive responses to threat during uncertainty. However, the precise prefrontal circuits necessary for discriminating a previously threatening context from a neutral context remain unknown. Using a combination of single-unit recordings and optogenetic manipulations, we identified a neuronal subpopulation in the dorsal medial prefrontal cortex (dmPFC) that projects to the lateral and ventrolateral periaqueductal gray (l/vlPAG) and is selectively activated during contextual fear discrimination. Moreover, optogenetic activation and inhibition of this neuronal population promoted contextual fear discrimination and generalization, respectively. Our results identify a subpopulation of dmPFC-l/vlPAG-projecting neurons that control switching between different emotional states during contextual discrimination.

23/01/2018 | Cell Rep   IF 8
Organization of Valence-Encoding and Projection-Defined Neurons in the Basolateral Amygdala.
Beyeler A, Chang CJ, Silvestre M, Leveque C, Namburi P, Wildes CP, Tye KM

The basolateral amygdala (BLA) mediates associative learning for both fear and reward. Accumulating evidence supports the notion that different BLA projections distinctly alter motivated behavior, including projections to the nucleus accumbens (NAc), medial aspect of the central amygdala (CeM), and ventral hippocampus (vHPC). Although there is consensus regarding the existence of distinct subsets of BLA neurons encoding positive or negative valence, controversy remains regarding the anatomical arrangement of these populations. First, we map the location of more than 1,000 neurons distributed across the BLA and recorded during a Pavlovian discrimination task. Next, we determine the location of projection-defined neurons labeled with retrograde tracers and use CLARITY to reveal the axonal path in 3-dimensional space. Finally, we examine the local influence of each projection-defined populations within the BLA. Understanding the functional and topographical organization of circuits underlying valence assignment could reveal fundamental principles about emotional processing.

2018 | front pharmacol   IF 3.8
NPV-BSK805, an Antineoplastic Jak2 Inhibitor Effective in Myeloproliferative Disorders, Causes Adiposity in Mice by Interfering With the Action of Leptin.
Haissaguerre M, Ferriere A, Clark S, Guzman-Quevedo O, Tabarin A, Cota D

The pathophysiology of body weight gain that is observed in patients suffering from myeloproliferative neoplasms treated with inhibitors of the janus kinase (Jak) 1 and 2 pathway remains unknown. Here we hypothesized that this class of drugs interferes with the metabolic actions of leptin, as this hormone requires functional Jak2 signaling. To test this, C57BL/6J chow-fed mice received either chronic intraperitoneal (ip) or repeated intracerebroventricular (icv) administration of the selective Jak2 inhibitor NVP-BSK805, which was proven efficacious in treating polycythemia in rodents. Changes in food intake, body weight and body composition were recorded. Icv NVP-BSK805 was combined with ip leptin to evaluate ability to interfere with the action of this hormone on food intake and on induction of hypothalamic phosphorylation of signal transducer and activator of transcription 3 (STAT3). We found that chronic peripheral administration of NVP-BSK805 did not alter food intake, but increased fat mass and feed efficiency. The increase in fat mass was more pronounced during repeated icv administration of the compound, suggesting that metabolic effects were related to molecular interference in brain structures regulating energy balance. Accordingly, acute icv administration of NVP-BSK805 prevented the ability of leptin to decrease food intake and body weight by impeding STAT3 phosphorylation within the hypothalamus. Consequently, acute icv administration of NVP-BSK805 at higher dose induced hyperphagia and body weight gain. Our results provide evidence for a specific anabolic effect exerted by antineoplastic drugs targeting the Jak2 pathway, which is due to interference with the actions of leptin. Consequently, assessment of metabolic variables related to increased fat mass gain should be performed in patients treated with Jak2 inhibitors.

2018 | Methods Mol Biol
Stool DNA Integrity Method for Colorectal Cancer Detection.
Rengucci C, De Maio G, Menghi M, Calistri D

Fluorescence long DNA (FL-DNA) is a non-invasive and simple-to-perform stool DNA test. This assay consists of a qualitative and quantitative real-time PCR (RT PCR) analysis. FL-DNA has great potential in colorectal cancer (CRC) lesions detection used alone or in combination with the standard CRC screening tool: immunochemical fecal occult blood test (iFOBT).

24/11/2017 | cell cycle   IF 3.5
Regulation of RNA polymerase III transcription during transformation of human IMR90 fibroblasts with defined genetic elements.
Durrieu-Gaillard S, Dumay-Odelot H, Boldina G, Tourasse NJ, Allard D, Andre F, Macari F, Choquet A, Lagarde P, Drutel G, Leste-Lasserre T, Petitet M, Lesluyes T, Lartigue-Faustin L, Dupuy JW, Chibon F, Roeder RG, Joubert D, Vagner S, Teichmann M

RNA polymerase (Pol) III transcribes small untranslated RNAs that are essential for cellular homeostasis and growth. Its activity is regulated by inactivation of tumor suppressor proteins and overexpression of the oncogene c-MYC, but the concerted action of these tumor-promoting factors on Pol III transcription has not yet been assessed. In order to comprehensively analyse the regulation of Pol III transcription during tumorigenesis we employ a model system that relies on the expression of five genetic elements to achieve cellular transformation. Expression of these elements in six distinct transformation intermediate cell lines leads to the inactivation of TP53, RB1, and protein phosphatase 2A, as well as the activation of RAS and the protection of telomeres by TERT, thereby conducting to full tumoral transformation of IMR90 fibroblasts. Transformation is accompanied by moderately enhanced levels of a subset of Pol III-transcribed RNAs (7SK; MRP; H1). In addition, mRNA and/or protein levels of several Pol III subunits and transcription factors are upregulated, including increased protein levels of TFIIIB and TFIIIC subunits, of SNAPC1 and of Pol III subunits. Strikingly, the expression of POLR3G and of SNAPC1 is strongly enhanced during transformation in this cellular transformation model. Collectively, our data indicate that increased expression of several components of the Pol III transcription system accompanied by a 2-fold increase in steady state levels of a subset of Pol III RNAs is sufficient for sustaining tumor formation.

22/11/2017 | Psychopharmacology (Berl)   IF 3.3
Synergistic enhancing-memory effect of donepezil and S 47445, an AMPA positive allosteric modulator, in middle-aged and aged mice.
Bretin S, Krazem A, Henkous N, Froger-Colleaux C, Mocaer E, Louis C, Perdaems N, Marighetto A, Beracochea D

Positive allosteric modulators of AMPA receptors (AMPA-PAMs) are described to facilitate cognitive processes in different memory-based models. Among them, S 47445 is a novel potent and selective AMPA-PAM. In order to assess its efficacy after repeated administration, S 47445 effect was evaluated in two aging-induced memory dysfunction tasks in old mice, one short-term working memory model evaluated in a radial maze task and one assessing contextual memory performance. S 47445 was shown to improve cognition in both models sensitive to aging. In fact, administration of S 47445 at 0.3 mg/kg (s.c.) reversed the age-induced deficits of the working memory model whatever the retention interval. Moreover, in the contextual task, S 47445 also reversed the age-induced deficit at all tested doses (from 0.03 to 0.3 mg/kg, p.o.). Since donepezil, an acetylcholinesterase inhibitor, induces only moderate symptomatic effects on memory in Alzheimer's disease patients, an alternative strategy for treatment of cognitive symptoms could be to act simultaneously on both glutamatergic AMPA receptors and cholinergic pathways by combining pharmacological treatments. The present study further examined such effects by assessing combinations of S 47445 and donepezil given orally during 9 days in aged C57/Bl6J mice using contextual memory task (CSD) and the working memory model of serial alternation task (AT). Interestingly, a significant synergistic memory-enhancing effect was observed with the combination of donepezil at 0.1 mg/kg with S 47445 at 0.1 mg/kg p.o. in the CSD or with S 47445 at 0.1 and 0.3 mg/kg in AT in comparison to compounds given alone and without any pharmacokinetic interaction.

20/11/2017 | hepatology   IF 13.2
New insights into diagnosis and therapeutic options for proliferative hepatoblastoma.
Hooks KB, Audoux J, Fazli H, Lesjean S, Ernault T, Senant ND, Leste-Lasserre T, Hagedorn M, Rousseau B, Danet C, Branchereau S, Brugieres L, Taque S, Guettier C, Fabre M, Rullier A, Buendia MA, Commes T, Grosset CF, Raymond AA

Surgery and cisplatin-based treatment of hepatoblastoma (HB) currently guarantee the survival of 70-80% of patients. However, some important challenges remain in diagnosing high risk tumors and identifying relevant targetable pathways offering new therapeutic avenues. Previously, two molecular subclasses of hepatoblastoma tumors have been described, namely C1 and C2; C2 being the subgroup with the poorest prognosis, a more advanced tumor stage and the worst overall survival rate. An associated 16-gene signature to discriminate the two tumoral subgroups was proposed but it has not been transferred into clinical routine. To address these issues we performed RNA sequencing of 25 tumors and matched normal liver samples from patients. The transcript profiling separated HB into three distinct subgroups named C1, C2A and C2B, identifiable by a concise four-gene signature: HSD17B6, ITGA6, TOP2A and VIM, with TOP2A being characteristic for the proliferative C2A tumors. Differential expression of these genes was confirmed by RT-qPCR on an expanded cohort and by immunohistochemistry. We also revealed significant overexpression of genes involved in Fanconi Anemia (FA) pathway in the C2A subgroup. We then investigated the ability of several described FA inhibitors to block growth of HB cells in vitro and in vivo. We demonstrated that bortezomib, an FDA-approved proteasome inhibitor, strongly impairs the proliferation and survival of HB cell lines in vitro, blocks FA pathway associated double-strand DNA repair and significantly impedes HB growth in vivo. In conclusion, the highly proliferating C2A subtype is characterized by TOP2A gene up-regulation and FA pathway activation and HB therapeutic arsenal could include Bortezomib for the treatment of patients with the most aggressive tumors. This article is protected by copyright. All rights reserved.

01/11/2017 | J Clin Invest   IF 12.8
Adipocyte cannabinoid receptor CB1 regulates energy homeostasis and alternatively activated macrophages.
Ruiz de Azua I, Mancini G, Srivastava RK, Rey AA, Cardinal P, Tedesco L, Zingaretti CM, Sassmann A, Quarta C, Schwitter C, Conrad A, Wettschureck N, Vemuri VK, Makriyannis A, Hartwig J, Mendez-Lago M, Bindila L, Monory K, Giordano A, Cinti S, Marsicano G, Offermanns S, Nisoli E, Pagotto U, Cota D, Lutz B

Dysregulated adipocyte physiology leads to imbalanced energy storage, obesity, and associated diseases, imposing a costly burden on current health care. Cannabinoid receptor type-1 (CB1) plays a crucial role in controlling energy metabolism through central and peripheral mechanisms. In this work, adipocyte-specific inducible deletion of the CB1 gene (Ati-CB1-KO) was sufficient to protect adult mice from diet-induced obesity and associated metabolic alterations and to reverse the phenotype in already obese mice. Compared with controls, Ati-CB1-KO mice showed decreased body weight, reduced total adiposity, improved insulin sensitivity, enhanced energy expenditure, and fat depot-specific cellular remodeling toward lowered energy storage capacity and browning of white adipocytes. These changes were associated with an increase in alternatively activated macrophages concomitant with enhanced sympathetic tone in adipose tissue. Remarkably, these alterations preceded the appearance of differences in body weight, highlighting the causal relation between the loss of CB1 and the triggering of metabolic reprogramming in adipose tissues. Finally, the lean phenotype of Ati-CB1-KO mice and the increase in alternatively activated macrophages in adipose tissue were also present at thermoneutral conditions. Our data provide compelling evidence for a crosstalk among adipocytes, immune cells, and the sympathetic nervous system (SNS), wherein CB1 plays a key regulatory role.

11/2017 | Nat Neurosci   IF 17.8
Synapse-specific astrocyte gating of amygdala-related behavior.
Martin-Fernandez M, Jamison S, Robin LM, Zhao Z, Martin ED, Aguilar J, Benneyworth MA, Marsicano G, Araque A

The amygdala plays key roles in fear and anxiety. Studies of the amygdala have largely focused on neuronal function and connectivity. Astrocytes functionally interact with neurons, but their role in the amygdala remains largely unknown. We show that astrocytes in the medial subdivision of the central amygdala (CeM) determine the synaptic and behavioral outputs of amygdala circuits. To investigate the role of astrocytes in amygdala-related behavior and identify the underlying synaptic mechanisms, we used exogenous or endogenous signaling to selectively activate CeM astrocytes. Astrocytes depressed excitatory synapses from basolateral amygdala via A1 adenosine receptor activation and enhanced inhibitory synapses from the lateral subdivision of the central amygdala via A2A receptor activation. Furthermore, astrocytic activation decreased the firing rate of CeM neurons and reduced fear expression in a fear-conditioning paradigm. Therefore, we conclude that astrocyte activity determines fear responses by selectively regulating specific synapses, which indicates that animal behavior results from the coordinated activity of neurons and astrocytes.

11/2017 | Cell Calcium   IF 3.7
Dynamics of surface neurotransmitter receptors and transporters in glial cells: Single molecule insights.
Ciappelloni S, Murphy-Royal C, Dupuis JP, Oliet SHR, Groc L

The surface dynamics of neurotransmitter receptors and transporters, as well as ion channels, has been well-documented in neurons, revealing complex molecular behaviour and key physiological functions. However, our understanding of the membrane trafficking and dynamics of the signalling molecules located at the plasma membrane of glial cells is still in its infancy. Yet, recent breakthroughs in the field of glial cells have been obtained using combination of superresolution microscopy, single molecule imaging, and electrophysiological recordings. Here, we review our current knowledge on the surface dynamics of neurotransmitter receptors, transporters and ion channels, in glial cells. It has emerged that the brain cell network activity, synaptic activity, and calcium signalling, regulate the surface distribution and dynamics of these molecules. Remarkably, the dynamics of a given neurotransmitter receptor/transporter at the plasma membrane of a glial cell or neuron is unique, revealing the existence of cell-type specific regulatory pathways. Thus, investigating the dynamics of signalling proteins at the surface of glial cells will likely shed new light on our understanding of glial cell physiology and pathology.

31/10/2017 | Cereb Cortex   IF 6.6
Pathway-Specific Control of Striatal Neuron Vulnerability by Corticostriatal Cannabinoid CB1 Receptors.
Ruiz-Calvo A, Maroto IB, Bajo-Graneras R, Chiarlone A, Gaudioso A, Ferrero JJ, Resel E, Sanchez-Prieto J, Rodriguez-Navarro JA, Marsicano G, Galve-Roperh I, Bellocchio L, Guzman M

The vast majority of neurons within the striatum are GABAergic medium spiny neurons (MSNs), which receive glutamatergic input from the cortex and thalamus, and form two major efferent pathways: the direct pathway, expressing dopamine D1 receptor (D1R-MSNs), and the indirect pathway, expressing dopamine D2 receptor (D2R-MSNs). While molecular mechanisms of MSN degeneration have been identified in animal models of striatal damage, the molecular factors that dictate a selective vulnerability of D1R-MSNs or D2R-MSNs remain unknown. Here, we combined genetic, chemogenetic, and pharmacological strategies with behavioral and neurochemical analyses, and show that the pool of cannabinoid CB1 receptor (CB1R) located on corticostriatal terminals efficiently safeguards D1R-MSNs, but not D2R-MSNs, from different insults. This cell-specific response relies on the regulation of glutamatergic signaling, and is independent from the CB1R-dependent control of astroglial activity in the striatum. These findings define cortical CB1R as a pivotal synaptic player in dictating a differential vulnerability of D1R-MSNs versus D2R-MSNs, and increase our understanding of the role of coordinated cannabinergic-glutamatergic signaling in establishing corticostriatal circuits and its dysregulation in neurodegenerative diseases.