Neurocentre Magendie


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61 publications

* equal contribution
Les IF indiqués ont été collectés par le Web of Sciences en Juin 2016

KEY POINTS: Vagal sensory inputs transmit information from the viscera to brainstem neurones located in the nucleus tractus solitarii to set physiological parameters. These excitatory synapses exhibit a CB1 endocannabinoid-induced long-term depression (LTD) triggered by vagal fibre stimulation. We investigated the impact of nutritional status on long-term changes in this long-term synaptic plasticity. Food deprivation prevents LTD induction by disrupting CB1 receptor signalling. Short-term refeeding restores the capacity of vagal synapses to express LTD. Ghrelin and cholecystokinin, respectively released during fasting and refeeding, play a key role in the control of LTD via the activation of energy sensing pathways such as AMPK and the mTOR and ERK pathways. ABSTRACT: Communication form the viscera to the brain is essential to set physiological homoeostatic parameters but also to drive more complex behaviours such as mood, memory and emotional states. Here we investigated the impact of the nutritional status on long-term changes in excitatory synaptic transmission in the nucleus tractus solitarii, a neural hub integrating visceral signals. These excitatory synapses exhibit a CB1 endocannabinoid (eCB)-induced long-term depression (LTD) triggered by vagal fibre stimulation. Since eCB signalling is known to be an important component of homoeostatic regulation of the body and is regulated during various stressful conditions, we tested the hypothesis that food deprivation alters eCB signalling in central visceral afferent fibres. Food deprivation prevents eCB-LTD induction due to the absence of eCB signalling. This loss was reversed by blockade of ghrelin receptors. Activation of the cellular fuel sensor AMP-activated protein kinase or inhibition of the mechanistic target of rapamycin pathway abolished eCB-LTD in free-fed rats. Signals associated with energy surfeit, such as short-term refeeding, restore eCB-LTD induction, which in turn requires activation of cholecystokinin receptors and the extracellular signal-regulated kinase pathway. These data suggest a tight link between eCB-LTD in the NTS and nutritional status and shed light on the key role of eCB in the integration of visceral information.

08/07/2016 | cell death differ   IF 8.2
Astroglial connexin43 contributes to neuronal suffering in a mouse model of Alzheimer's disease.
Yi C, Mei X, Ezan P, Mato S, Matias I, Giaume C, Koulakoff A

In Alzheimer's disease (AD), astrocyte properties are modified but their involvement in this pathology is only beginning to be appreciated. The expression of connexins, proteins forming gap junction channels and hemichannels, is increased in astrocytes contacting amyloid plaques in brains of AD patients and APP/PS1 mice. The consequences on their channel functions was investigated in a murine model of familial AD, the APPswe/PS1dE9 mice. Whereas gap junctional communication was not affected, we revealed that hemichannels were activated in astrocytes of acute hippocampal slices containing Abeta plaques. Such hemichannel activity was detected in all astrocytes, whatever their distance from amyloid plaques, but with an enhanced activity in the reactive astrocytes contacting amyloid plaques. Connexin43 was the main hemichannel contributor, however, a minor pannexin1 component was also identified in the subpopulation of reactive astrocytes in direct contact with plaques. Distinct regulatory pathways are involved in connexin and pannexin hemichannel activation. Inflammation triggered pannexin hemichannel activity, whereas connexin43 hemichannels were activated by the increase in resting calcium level of astrocytes. Importantly, hemichannel activation led to the release of ATP and glutamate that contributed to maintain a high calcium level in astrocytes placing them in the center of a vicious circle. The astroglial targeted connexin43 gene knocking-out in APPswe/PS1dE9 mice allowed to diminish gliotransmitter release and to alleviate neuronal damages, reducing oxidative stress and neuritic dystrophies in hippocampal neurons associated to plaques. Altogether, these data highlight the importance of astroglial hemichannels in AD and suggest that blocking astroglial hemichannel activity in astrocytes could represent an alternative therapeutic strategy in AD.Cell Death and Differentiation advance online publication, 8 July 2016; doi:10.1038/cdd.2016.63.

30/01/2015 | Glia   IF 6
Activated microglia impairs neuroglial interaction by opening Cx43 hemichannels in hippocampal astrocytes.
Abudara V, Roux L, Dallerac G, Matias I, Dulong J, Mothet JP, Rouach N, Giaume C

Glia plays an active role in neuronal functions and dysfunctions, some of which depend on the expression of astrocyte connexins, the gap junction channel and hemichannel proteins. Under neuroinflammation triggered by the endotoxin lipopolysacharide (LPS), microglia is primary stimulated and releases proinflammatory agents affecting astrocytes and neurons. Here, we investigate the effects of such microglial activation on astrocyte connexin-based channel functions and their consequences on synaptic activity in an ex vivo model. We found that LPS induces astroglial hemichannel opening in acute hippocampal slices while no change is observed in gap junctional communication. Based on pharmacological and genetic approaches we found that the LPS-induced hemichannel opening is mainly due to Cx43 hemichannel activity. This process primarily requires a microglial stimulation resulting in the release of at least two proinflammatory cytokines, IL-1beta and TNF-alpha. Consequences of the hemichannel-mediated increase in membrane permeability are a calcium rise in astrocytes and an enhanced glutamate release associated to a reduction in excitatory synaptic activity of pyramidal neurons in response to Schaffer's collateral stimulation. As a whole our findings point out astroglial hemichannels as key determinants of the impairment of synaptic transmission during neuroinflammation. GLIA 2015.

This study examined the respective influences of cannabinoid type-1 (CB1 ) receptors expressed either in forebrain GABAergic neurons, in cortical glutamatergic neurons or in astrocytes on the turnover rates of the endocannabinoids N-arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), and the non-cannabinoid N-acylethanolamides, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), in mouse forebrain regions. To this end, conditional mutant mice lacking CB1 receptors from either of these cell types were pretreated systemically with JZL195, a dual inhibitor of fatty acid amide hydrolase, the enzyme degrading AEA, PEA and OEA, and of monoacylglycerol lipase, the main 2-AG-degrading enzyme. The analyses of frontocortical, hippocampal and striatal AEA, 2-AG, PEA and OEA concentrations revealed that their respective baseline concentrations were not influenced by the mouse genotype. On the other hand, the accumulation of frontocortical and/or hippocampal 2-AG levels in JZL195-pretreated mice was dependent on the mouse genotype. Thus, JZL195-induced 2-AG accumulation rates were diminished in the frontal cortex of mice lacking CB1 receptors in glutamatergic neurons whilst their respective values were increased in the frontal cortex and hippocampus of mice lacking these receptors in astrocytes. These genotypic differences occurred with parallel and proportionate changes in the fractional rate constants for degradation of 2-AG, thus providing a mechanism whereby the baseline levels of 2-AG remained constant between genotypes. Besides suggesting a cell-type-specific control of frontocortical and/or hippocampal 2-AG synthesis and degradation rates by CB1 receptors, this study highlights the interest of assessing endocannabinoid turnover rates when questioning the status of the endocannabinoid system. This article is protected by copyright. All rights reserved.

03/2014 | Nat Neurosci   IF 16.7
The endocannabinoid system controls food intake via olfactory processes.
Soria-Gomez E, Bellocchio L, Reguero L, Lepousez G, Martin C, Bendahmane M, Ruehle S, Remmers F, Desprez T, Matias I, Wiesner T, Cannich A, Nissant A, Wadleigh A, Pape HC, Chiarlone AP, Quarta C, Verrier D, Vincent P, Massa F, Lutz B, Guzman M, Gurden H, Ferreira G, Lledo PM, Grandes P, Marsicano G

Hunger arouses sensory perception, eventually leading to an increase in food intake, but the underlying mechanisms remain poorly understood. We found that cannabinoid type-1 (CB1) receptors promote food intake in fasted mice by increasing odor detection. CB1 receptors were abundantly expressed on axon terminals of centrifugal cortical glutamatergic neurons that project to inhibitory granule cells of the main olfactory bulb (MOB). Local pharmacological and genetic manipulations revealed that endocannabinoids and exogenous cannabinoids increased odor detection and food intake in fasted mice by decreasing excitatory drive from olfactory cortex areas to the MOB. Consistently, cannabinoid agonists dampened in vivo optogenetically stimulated excitatory transmission in the same circuit. Our data indicate that cortical feedback projections to the MOB crucially regulate food intake via CB1 receptor signaling, linking the feeling of hunger to stronger odor processing. Thus, CB1 receptor-dependent control of cortical feedback projections in olfactory circuits couples internal states to perception and behavior.

25/07/2013 | Obesity (Silver Spring)   IF 3.4
Leucine supplementation modulates fuel substrates utilization and glucose metabolism in previously obese mice.
Binder E, Bermudez-Silva FJ, Elie M, Leste-Lasserre T, Belluomo I, Clark S, Duchampt A, Mithieux G, Cota D

OBJECTIVE: High-protein diets favor weight loss and its maintenance. Whether these effects might be recapitulated by certain amino acids is unknown. Therefore, the impact of leucine supplementation on energy balance and associated metabolic changes in diet-induced obese (DIO) mice during and after weight loss was investigated. DESIGN AND METHODS: DIO C57BL/6J mice were fed a normocaloric diet to induce weight loss while receiving or not the amino acid leucine in drinking water. Body weight, food intake, body composition, energy expenditure, glucose tolerance, insulin, and leptin sensitivity were evaluated. Q-PCR analysis was performed on muscle, brown and white adipose tissues. RESULTS: DIO mice decreased body weight and fat mass in response to chow, but supplementation with leucine did not affect these parameters. During weight maintenance, mice supplemented with leucine had improved glucose tolerance, increased leptin sensitivity, and lower respiratory quotient. The latter was associated with changes in the expression of several genes modulating fatty acid metabolism and mitochondrial activity in the epididymal white and the brown adipose tissues, but not muscle. CONCLUSIONS: Leucine supplementation might represent an adjuvant beneficial nutritional therapy during weight loss and maintenance, because it improves lipid and glucose metabolism and restores leptin sensitivity in previously obese animals.

07/2013 | J Clin Endocrinol Metab   IF 6.2
Androgen profiling by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in healthy normal-weight ovulatory and anovulatory late adolescent and young women.
Fanelli F, Gambineri A, Belluomo I, Repaci A, Di Lallo VD, Di Dalmazi G, Mezzullo M, Prontera O, Cuomo G, Zanotti L, Paccapelo A, Morselli-Labate AM, Pagotto U, Pasquali R

CONTEXT: Physiological transient imbalance typical of adolescence needs to be distinguished from hyperandrogenism-related dysfunction. The accurate determination of circulating androgens is the best indicator of hyperandrogenism. However, reliable reference intervals for adolescent and young women are not available. OBJECTIVE: The aim of the study was to define androgen reference intervals in young women and to analyze the impact of the menstrual phase and ovulation efficiency over the androgen profile as assessed by reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. PARTICIPANTS: Female high school students aged 16-19 years were included in the study. MAIN OUTCOME MEASURES: The study was performed on reference subjects properly selected among an unbiased population. Normal-weight, drug and disease free, eumenorrheic females with no signs of hyperandrogenism were included. The steroid hormone profile was determined by a validated in-house LC-MS/MS method. A statistical estimation of overall and menstrual phase-specific reference intervals was performed. A subgroup of anovulatory females was identified based on progesterone circulating levels. The impact of ovulation efficiency over hormonal profile was analyzed. RESULTS: A total of 159 females satisfied healthy criteria. Androgen levels did not vary according to menstrual phase, but a significantly higher upper reference limit was found for T in the luteal phase compared to the follicular phase. Higher T and androstenedione levels were observed in anovulatory compared to ovulatory females, paralleled by higher LH and FSH and lower 17-hydroxyprogesterone and 17beta-estradiol levels. CONCLUSIONS: This is the first study providing LC-MS/MS-based, menstrual phase-specific reference intervals for the circulating androgen profile in young females. We identified a subgroup of anovulatory healthy females characterized by androgen imbalance.

01/05/2013 | Biol Psychiatry   IF 8.9
Ventral tegmental area cannabinoid type-1 receptors control voluntary exercise performance.
Dubreucq S, Durand A, Matias I, Benard G, Richard E, Soria-Gomez E, Glangetas C, Groc L, Wadleigh A, Massa F, Bartsch D, Marsicano G, Georges F, Chaouloff F

BACKGROUND: We have shown that the endogenous stimulation of cannabinoid type-1 (CB(1)) receptors is a prerequisite for voluntary running in mice, but the precise mechanisms through which the endocannabinoid system exerts a tonic control on running performance remain unknown. METHODS: We analyzed the respective impacts of constitutive/conditional CB(1) receptor mutations and of CB(1) receptor blockade on wheel-running performance. We then assessed the consequences of ventral tegmental area (VTA) CB(1) receptor blockade on the wheel-running performances of wildtype (gamma-aminobutyric acid [GABA]-CB(1)(+)/(+)) and mutant (GABA-CB(1)(-)/(-)) mice for CB(1) receptors in brain GABA neurons. Using in vivo electrophysiology, the consequences of wheel running on VTA dopamine (DA) neuronal activity were examined in GABA-CB(1)(+)/(+) and GABA-CB(1)(-)/(-) mice. RESULTS: Conditional deletion of CB(1) receptors from brain GABA neurons, but not from several other neuronal populations or from astrocytes, decreased wheel-running performance in mice. The inhibitory consequences of either the systemic or the intra-VTA administration of CB1 receptor antagonists on running behavior were abolished in GABA-CB(1)(-)/(-) mice. The absence of CB1 receptors from GABAergic neurons led to a depression of VTA DA neuronal activity after acute/repeated wheel running. CONCLUSIONS: This study provides evidence that CB(1) receptors on VTA GABAergic terminals exert a permissive control on rodent voluntary running performance. Furthermore, it is shown that CB(1) receptors located on GABAergic neurons impede negative consequences of voluntary exercise on VTA DA neuronal activity. These results position the endocannabinoid control of inhibitory transmission as a prerequisite for wheel-running performance in mice.

2013 | PLoS ONE   IF 3.1
Leucine supplementation protects from insulin resistance by regulating adiposity levels.
Binder E, Bermudez-Silva FJ, Andre C, Elie M, Romero-Zerbo SY, Leste-Lasserre T, Belluomo L, Duchampt A, Clark S, Aubert A, Mezzullo M, Fanelli F, Pagotto U, Laye S, Mithieux G, Cota D

BACKGROUND: Leucine supplementation might have therapeutic potential in preventing diet-induced obesity and improving insulin sensitivity. However, the underlying mechanisms are at present unclear. Additionally, it is unclear whether leucine supplementation might be equally efficacious once obesity has developed. METHODOLOGY/PRINCIPAL FINDINGS: Male C57BL/6J mice were fed chow or a high-fat diet (HFD), supplemented or not with leucine for 17 weeks. Another group of HFD-fed mice (HFD-pairfat group) was food restricted in order to reach an adiposity level comparable to that of HFD-Leu mice. Finally, a third group of mice was exposed to HFD for 12 weeks before being chronically supplemented with leucine. Leucine supplementation in HFD-fed mice decreased body weight and fat mass by increasing energy expenditure, fatty acid oxidation and locomotor activity in vivo. The decreased adiposity in HFD-Leu mice was associated with increased expression of uncoupling protein 3 (UCP-3) in the brown adipose tissue, better insulin sensitivity, increased intestinal gluconeogenesis and preservation of islets of Langerhans histomorphology and function. HFD-pairfat mice had a comparable improvement in insulin sensitivity, without changes in islets physiology or intestinal gluconeogenesis. Remarkably, both HFD-Leu and HFD-pairfat mice had decreased hepatic lipid content, which likely helped improve insulin sensitivity. In contrast, when leucine was supplemented to already obese animals, no changes in body weight, body composition or glucose metabolism were observed. CONCLUSIONS/SIGNIFICANCE: These findings suggest that leucine improves insulin sensitivity in HFD-fed mice by primarily decreasing adiposity, rather than directly acting on peripheral target organs. However, beneficial effects of leucine on intestinal gluconeogenesis and islets of Langerhans's physiology might help prevent type 2 diabetes development. Differently, metabolic benefit of leucine supplementation is lacking in already obese animals, a phenomenon possibly related to the extent of the obesity before starting the supplementation.

2013 | Mol Metab   IF 5.4
Astroglial CB1 cannabinoid receptors regulate leptin signaling in mouse brain astrocytes.
Bosier B, Bellocchio L, Metna-Laurent M, Soria-Gomez E, Matias I, Hebert-Chatelain E, Cannich A, Maitre M, Leste-Lasserre T, Cardinal P, Mendizabal-Zubiaga J, Canduela MJ, Reguero L, Hermans E, Grandes P, Cota D, Marsicano G

Type-1 cannabinoid (CB1) and leptin (ObR) receptors regulate metabolic and astroglial functions, but the potential links between the two systems in astrocytes were not investigated so far. Genetic and pharmacological manipulations of CB1 receptor expression and activity in cultured cortical and hypothalamic astrocytes demonstrated that cannabinoid signaling controls the levels of ObR expression. Lack of CB1 receptors also markedly impaired leptin-mediated activation of signal transducers and activators of transcription 3 and 5 (STAT3 and STAT5) in astrocytes. In particular, CB1 deletion determined a basal overactivation of STAT5, thereby leading to the downregulation of ObR expression, and leptin failed to regulate STAT5-dependent glycogen storage in the absence of CB1 receptors. These results show that CB1 receptors directly interfere with leptin signaling and its ability to regulate glycogen storage, thereby representing a novel mechanism linking endocannabinoid and leptin signaling in the regulation of brain energy storage and neuronal functions.