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La pratique du binge drinking (BD) se caractérise par l’alternance répétée d’épisodes d’alcoolisation rapide et massive, dans le but d’atteindre l’ivresse, et de périodes d’abstinence. Une telle modalité de consommation d’alcool est communément rencontrée chez les jeunes. Elle entraîne des déficits cognitifs en impliquant probablement des processus neuroinflammatoires et épigénétiques. Toutefois, le mode d’action de l’alcool au cours des expositions initiales de type BD, est peu connu. Il pourrait pourtant être à l’origine de ces déficits cognitifs à long terme. Des études récentes, réalisées chez le rat adolescent, révèlent que la perte de mémoire se produit dès les premiers BD, avec des mécanismes similaires à ceux d’une exposition plus longue. L’initiation au BD chez le jeune serait donc responsable de déficits qui seront probablement entretenus par la répétition de cette pratique. Ces données originales devraient permettre de renforcer les campagnes de prévention auprès de la jeune population qui pratique le BD.

BACKGROUND Multiple ethanol binge drinking-like exposures during adolescence in rat induce neuroinflammation, neurogenesis loss and cognitive deficits at adulthood. Interestingly, the very first ethanol binge drinking-like exposures during adolescence also induce cognitive and synaptic plasticity impairments in the hippocampus at short term while the cellular mechanisms of these effects remain unclear. Here, we sought to determine which of the cellular effects of ethanol might play a role in cognitive and synaptic plasticity disturbances observed in adolescent male rat after only two binge-like ethanol exposures. METHODS Using immunochemistry, we determined neurogenesis, neuronal loss, astrogliosis, neuroinflammation and synaptogenesis in the hippocampus of adolescent rat 48h after two binge-like ethanol exposures (3 g/kg, i.p, 9 hours apart). Flow cytometry was used to analyze activated microglia and to identify the TLR4 expressing cell types. RESULTS Increased DCX immunoreactivity was detected in the subgranular zone (SGZ) of the dentate gyrus (DG) together with astrogliosis in the SGZ and a lower number of mature neurons in the DG and in CA3, suggesting compensatory neurogenesis. Synaptic density decreased in the stratum oriens of CA1 revealing structural plasticity. There was no change in microglial TLR4 expression nor in the number of activated microglia, suggesting a lack of neuroinflammatory processes although neuronal TLR4 was decreased in CA1 and DG. CONCLUSIONS Our findings demonstrate that the cognitive deficits associated with hippocampal synaptic plasticity alterations that we previously characterized 48h after the very first binge-like exposures are associated with hippocampal structural plasticity, astrogliosis and decreased neuronal TLR4 expression, but not with microglia reactivity.

BACKGROUND Studying synaptic plasticity in the rat hippocampus slice is a well-established way to analyze cellular mechanisms related to learning and memory. Different modes of recording can be used, such as extracellular field excitatory post-synaptic potential (EPSP) and diverse patch-clamp methods. However, most studies using these methods have examined only up to the juvenile stage of brain maturation, which is known to terminate during late adolescence/early adulthood. Moreover, several animal models of human diseases have been developed at this late stage of brain development. To study the vulnerability of adolescent rat to the cognitive impairment of alcohol, we developed a model of binge-like exposure in which ethanol selectively abolishes low frequency stimulation (LFS)-induced, field EPSP long-term depression (LTD) in the rat hippocampus slice. METHODS In the present study, we sought to use whole-cell patch-clamp recording in the voltage-clamp mode to further investigate the mechanisms involved in the abolition of LFS-induced LTD in our model of binge-like exposure in adolescent rat hippocampus slices. In addition, we investigated LFS-induced NMDAR-LTD and mGluR-LTD at different ages and changed several parameters to improve the recordings. RESULTS Using patch-clamp recording, LFS-induced NMDAR-LTD and mGluR-LTD could be measured until 4 weeks of age, but not in older animals. Similarly, chemical mGluR-LTD and a combined LFS-LTD involving both N-Methyl-D-Aspartate Receptor (NMDAR) and mGluR were not measured in older animals. The absence of LFS-LTD was not due to the loss of a diffusible intracellular agent nor the voltage mode of recording or intracellular blockade of either sodium or potassium currents. In contrast to voltage-clamp recordings, LFS-induced LTD tested with field recordings was measured at all ages and the effects of EtOH were visible in all cases. CONCLUSIONS We concluded that whole-cell patch-clamp recordings are not suitable for studying synaptic LFS-induced LTD in rats older than 4 weeks of age and therefore cannot be used to explore electrophysiological disturbances, such as those induced by alcohol binge drinking during adolescence, which constitutes a late period of brain maturation.

International audience; Simple Summary Sorafenib is a treatment for advanced HCC which demonstrated a poor objective response rate due to important induction of resistance. We demonstrated that induction of acquired-resistance to sorafenib in Huh-7 cell line leads to the loss of SLAMF3 expression, a tumor suppressor receptor in HCC. In these cells, the sorafenib-resistant phenotype is characterized by the increase of aggressiveness and induction of the epithelial-to-mesenchymal transition. Acquired-resistance to sorafenib induce a multipotent mesenchymal stem cells characteristic. Interestingly, SLAMF3 overexpression reversed the epithelial-to-mesenchymal transition and decreased metastatic potential in sorafenib-resistant cells through the control of ERK1/2 and mTOR signaling pathways. SLAMF3 seems to be a theranostics tools to the management of sorafenib treatment. Background: Acquired resistance to sorafenib in hepatocellular carcinoma (HCC) patients results in poor prognosis. Epithelial-to-mesenchymal transition (EMT) is the major mechanism implicated in the resistance to sorafenib. We have reported the tumor suppressor role of SLAMF3 (signaling lymphocytic activation molecules family 3) in HCC progression and highlighted its implication in controlling the MRP-1 transporter activity. These data suggest the implication of SLAMF3 in sorafenib resistance mechanisms. Methods: We evaluated the resistance to sorafenib in Huh-7 cells treated with progressive doses (Res cells). We investigated the link between acquired resistance to sorafenib and SLAMF3 expression by flow cytometry and Western blot methods. Furthermore, we analyzed the EMT and the stem cell potential of cells resistant to sorafenib. Results: Sorafenib resistance was confirmed in Res cells by analyzing the cell viability in the presence of sorafenib. The mesenchymal transition, in Res cells, was confirmed by high migratory index and the expression of EMT antigens. Interestingly, we found that loss of SLAMF3 expression corresponded to sorafenib-resistant phenotypes. The overexpression of SLAMF3 reversed EMT, decreased metastatic potential and inhibited mTOR/ERK1/2 in Res cells. Conclusions: We propose that rescuing SLAMF3 expression in resistant cells could represent a potential therapeutic strategy to enhance sorafenib efficacy in HCC patients.

Alcohol use disorder is a chronic and highly relapsing disorder, characterized by a loss of control over alcohol consumption and craving. Several studies suggest a key role of glutamate in this disorder. In recent years, the modulation of cystine/glutamate exchange via the xc− system has emerged as a new therapeutic alternative for reducing the excitatory glutamatergic transmission observed after ethanol self-administration in both rats and humans. The objective of this study was to determine whether a treatment with N-acetylcysteine (NAC), a cystine prodrug, could reduce ethanol self-administration, ethanol-seeking behavior and reacquisition of ethanol self-administration. Male Long Evans rats were trained to self-administer 20 percent ethanol in operant cages for several weeks. Once the consumption surpassed 1 g of ethanol/kg body weight/15 minutes, the effect of an acute intraperitoneal injection of NAC (0, 25, 50 or 100 mg/kg) 1 hour before the beginning of each test was evaluated on different aspects of the operant self-administration behavior. We demonstrated antimotivational properties of NAC (100 mg/kg), as ethanol-reinforced responding was reduced in a fixed ratio (−35 percent) and in a progressive ratio schedule (−81 percent). NAC also reduced ethanol-seeking behavior (−77 percent) evaluated as extinction responding in a single extinction session. NAC was able to reduce reacquisition in rats that were abstinent for 17 days, while NAC had no effect on ethanol relapse in rats previously exposed to six extinction sessions. Overall, our results demonstrate that NAC limits motivation, seeking behavior and reacquisition in rats, making it a potential new treatment for the maintenance of abstinence.

Many components of ethanol addiction such as reinforcement, withdrawal, extinction, and relapse are known to involve glutamate transmission. NAC could counteract glutamatergic dysregulation underlying ethanol addiction. We previously demonstrated the efficacy of N-acetylcysteine (NAC) treatment to reduce ethanol consumption, motivation, seeking, and relapse in rats displaying a binge drinking-like phenotype. The current study assessed whether acute NAC could reduce ethanol self-administration, ethanol-seeking behavior, motivation, and reacquisition of ethanol self-administration following abstinence in ethanol-dependent rats. Ethanol dependence was induced by chronic intermittent ethanol (CIE) vapor exposure for 10 weeks in male Wistar rats. Effects of NAC (0, 25, 50 or 100 mg/kg; i.p.) were evaluated during acute withdrawal, 8 h after inhalation chambers were turned off. We evaluated NAC effect on the expression of the xCT protein expression (the target of NAC) and glutamate transporters (GLT-1) in dependent rats. We showed that in dependent rats, the low dose of NAC (25 mg/kg) reduced ethanol self-administration and motivation to consume ethanol, evaluated in a progressive ratio paradigm. At 50 mg/kg, but not 25 mg/kg, NAC reduced extinction responding and reacquisition of self-administration after 1 month abstinence. The xCT protein expression was decreased in the nucleus accumbens in dependent compared with ethanol-naive rats. Thus, NAC may be effective by decreasing glutamate transmission through presynaptic mechanisms (i.e. the stimulation of xc−-mediated increase in extrasynaptic glutamate levels). Our results demonstrate that NAC decreased ethanol self-administration, extinction responding, and relapse in ethanol-dependent animals, and thus strongly support clinical development of NAC for alcohol use disorders.

Ethanol (EtOH) induces cognitive impairment through modulation of synaptic plasticity notably in the hippocampus. The cellular mechanism(s) of these EtOH effects may range from synaptic signaling modulation to alterations of the epigenome. Previously, we reported that two binge-like exposures to EtOH (3 g/kg, ip, 9 h apart) in adolescent rats abolished long-term synaptic depression (LTD) in hippocampus slices, induced learning deficits, and increased N-methyl-d-aspartate (NMDA) receptor signaling through its GluN2B subunit after 48 hours. Here, we tested the hypothesis of EtOH-induced epigenetic alterations leading to modulation of GluN2B and GluN2A NMDA receptor subunits. Forty-two days old rats were treated with EtOH or the histone deacetylase inhibitor (HDACi) sodium butyrate (NaB, 600 mg/kg, ip) injected alone or 30 minutes before EtOH. After 48 hours, learning was tested with novel object recognition while synaptic plasticity and the role of GluN2A and GluN2B subunits in NMDA-fEPSP were measured in CA1 field of hippocampus slices. LTD and memory were impaired 48 hours after EtOH and NMDA-fEPSP analysis unraveled changes in the GluN2A/GluN2B balance. These results were associated with an increase in histone deacetylase (HDAC) activity and HDAC2 mRNA and protein while Ac-H4K12 labelling was decreased. EtOH increases expression of HDAC2 and mRNA level for GluN2B subunit (but not GluN2A), while HDAC2 modulates the promoter of the gene encoding GluN2B. Interestingly, NaB pretreatment prevented all the cellular and memory-impairing effects of EtOH. In conclusion, the memory-impairing effects of two binge-like EtOH exposure involve NMDA receptor-dependent LTD deficits due to a GluN2A/GluN2B imbalance resulting from changes in GluN2B expression induced by HDAC2.

Low to moderate perinatal ethanol exposure (PEE) may have disastrous consequences for the central nervous system resulting notably in permanent cognitive deficits. Learning and memory are mediated in the hippocampus by long-term potentiation (LTP) and long term depression (LTD), two forms of synaptic plasticity. PEE decreases LTP but also abnormally facilitates LTD (Kervern et al. 2015) through a presently unknown mechanism. We studied in rat hippocampus slice, the involvement of the chloride co-transporters NKCC1 and KCC2, in the role of GABAA inhibitions in facilitated LTD after moderate PEE. After PEE and in contrast to control slices, facilitated LTD in CA1 field was reduced by the GABAA receptor antagonist bicuculline with no changes in sensitivity to bicuculline and in GABA and benzodiazepine binding sites. Also, sensitivity to diazepam was unaltered, whereas aberrant LTD was blocked. Immunohistochemistry and protein analysis demonstrated an increase in KCC2 protein level at cell membrane in CA1 after PEE with no change in NKCC1 expression. Specifically, both monomeric and dimeric forms of KCC2 were increased in CA1. Bumetanide (10–100 μM), a dose-dependent blocker of NKCC1 and KCC2, or VU0240551 (10 μM) a specific antagonist of KCC2, corrected the enhanced LTD and interestingly bumetanide also restored the lower LTP after PEE. These results demonstrate for the first time an upregulation of the KCC2 co-transporter expression after moderate PEE associated with disturbances in GABAergic neurotransmission modulating bidirectional synaptic plasticity in the hippocampus. Importantly, bumetanide compensated deficits in both LTP and LTD, revealing its potential therapeutic properties.

Addiction is a chronic and highly relapsing disorder hypothesized to be produced by an imbalance between excitatory and inhibitory neurotransmission. For more than a decade, emerging evidence indicates that manipulation of glutamatergic neurotransmission, by group III mGlu receptors (mGlu4/7/8), could be a promising approach to develop therapeutic agents for the treatment of addiction. Thus, the aim of the present study is to determine whether LSP2-9166, a mixed mGlu4/mGlu7 orthosteric agonist, could reduce ethanol self-administration, ethanol motivation and reacquisition after protracted abstinence in a preclinical model of excessive ethanol intake. Male Long Evans rats were chronically trained to consume large amount of ethanol in operant cages for several weeks. Once they reached a stable level of consumption (about 1 g of pure ethanol/kg bodyweight/15min), the effect of LSP2-9166 was evaluated on different aspects of the operant self-administration behavior. In this study, we found that the intracerebroventricular infusion of LSP2-9166 dose dependently reduced ethanol consumption, motivation for ethanol and reacquisition of ethanol self-administration after abstinence. Together, these results support recent preclinical findings showing that pharmacological modulation of mGlu receptors may serve as an effective treatment for reducing ethanol consumption and relapse.

Alcohol use disorder is a devastating illness with a profound health impact, and its development is dependent on both genetic and environmental factors. This disease occurs over time and requires changes in brain gene expression. There is converging evidence suggesting that the epigenetic processes may play a role in the alcohol-induced gene regulations and behavior such as the intervention of DNA methylation and histone acetylation. Histone acetylation, like histone methylation, is a highly dynamic process regulated by two classes of enzymes: histone acetyltransferases and histone deacetylases (HDACs). To date, 18 human HDAC isoforms have been characterized, and based on their sequence homologies and cofactor dependencies, they have been phylogenetically categorized into 4 main classes: classes I, II (a and b), III, and IV. In the brain, expression of the different classes of HDACs varies between cell types and also in their subcellular localization (nucleus and/or cytosol). Furthermore, we recently showed that a single ethanol exposure inhibits HDAC activity and increases both H3 and H4 histone acetylation within the amygdala of rats. In the brain of alcoholic patients, ethanol has been shown to induce histone-related and DNA methylation epigenetic changes in several reward regions involved in reward processes such as hippocampus, prefrontal cortex, and amygdala. We recently demonstrated alteration of histone H3 acetylation levels in several brain regions from the reward circuit of rats made dependent to alcohol after chronic and intermittent exposure to ethanol vapor. In neuronal cell line culture, ethanol was shown to induce HDAC expression. In mouse and rat brain, numerous studies reported epigenetic alterations following ethanol exposure. We also demonstrated that both the expression of genes and the activity of enzymes involved in epigenetic mechanisms are changed after repeated administrations of ethanol in mice sensitized to the motor stimulant effect of ethanol (a model of drug-induced neuroplasticity). Numerous studies have shown that HDAC inhibitors are able to counter ethanol-induced behaviors and the ethanol-induced changes in the levels of HDAC and/or levels of acetylated HDAC. For example, trichostatin A (TSA) treatment caused the reversal of ethanol-induced tolerance, anxiety, and ethanol drinking by inhibiting HDAC activity, thereby increasing histone acetylation in the amygdala of rats. Another study demonstrated that TSA prevented the development of ethanol withdrawal induced anxiety in rats by rescuing deficits in histone acetylation induced by increased HDAC activity in the amygdala. We have demonstrated that treatment with the HDAC inhibitor sodium butyrate blocks both the development and the expression of ethanol-induced behavioral sensitization in mice. In this context, converging evidence indicates that HDAC inhibitors could be useful in counteracting ethanol-induced gene regulations via epigenetic mechanisms, that is, HDAC inhibitors could affect different acetylation sites and may also alter the expression of different genes that could in turn counteract the effect of ethanol. Recent work in rodents has shown that systemic administration of pan HDAC class I and II inhibitors, TSA and N-hydroxy-N-phenyl-octanediamide [SuberoylAnilide Hydroxamic Acid] (SAHA), and of the more selective inhibitor (mainly HDAC1 and HDAC9) MS-275, decrease binge-like alcohol drinking in mice. SAHA selectively reduced ethanol operant self-administration and seeking in rats. Our previous study revealed that MS-275 strongly decreased operant ethanol self-administration in alcohol-dependent rats when administered 30 minutes before the session at the second day of injection. We also demonstrated that intra-cerebro-ventricular infusion of MS-275 increases acetylation of Histone 4 within the nucleus accumbens and the dorsolateral striatum, associated to a decrease in ethanol self-administration by about 75%. MS-275 also diminished both the motivation to consume ethanol (25% decrease), relapse (by about 50%) and postponed reacquisition after abstinence. Both literature and several of our studies strongly support the potential therapeutic interest of targeting epigenetic mechanisms in excessive alcohol drinking and strengthen theinterest of focusing on specific isoforms of histone deacetylases.

International audience; Alcohol use disorder is a devastating illness with a profound health impact, and its development is dependent on both genetic and environmental factors. This disease occurs over time and requires changes in brain gene expression. There is converging evidence suggesting that the epigenetic processes may play a role in the alcohol-induced gene regulations and behavior such as the intervention of DNA methylation and histone acetylation. Histone acetylation, like histone methylation, is a highly dynamic process regulated by two classes of enzymes: histone acetyltransferases and histone deacetylases (HDACs). To date, 18 human HDAC isoforms have been characterized, and based on their sequence homologies and cofactor dependencies, they have been phylogenetically categorized into 4 main classes: classes I, II (a and b), III, and IV. In the brain, expression of the different classes of HDACs varies between cell types and also in their subcellular localization (nucleus and/or cytosol). Furthermore, we recently showed that a single ethanol exposure inhibits HDAC activity and increases both H3 and H4 histone acetylation within the amygdala of rats. In the brain of alcoholic patients, ethanol has been shown to induce histone-related and DNA methylation epigenetic changes in several reward regions involved in reward processes such as hippocampus, prefrontal cortex, and amygdala. We recently demonstrated alteration of histone H3 acetylation levels in several brain regions from the reward circuit of rats made dependent to alcohol after chronic and intermittent exposure to ethanol vapor. In neuronal cell line culture, ethanol was shown to induce HDAC expression. In mouse and rat brain, numerous studies reported epigenetic alterations following ethanol exposure. We also demonstrated that both the expression of genes and the activity of enzymes involved in epigenetic mechanisms are changed after repeated administrations of ethanol in mice sensitized to the motor stimulant effect of ethanol (a model of drug-induced neuroplasticity). Numerous studies have shown that HDAC inhibitors are able to counter ethanol-induced behaviors and the ethanol-induced changes in the levels of HDAC and/or levels of acetylated HDAC. For example, trichostatin A (TSA) treatment caused the reversal of ethanol-induced tolerance, anxiety, and ethanol drinking by inhibiting HDAC activity, thereby increasing histone acetylation in the amygdala of rats. Another study demonstrated that TSA prevented the development of ethanol withdrawal induced anxiety in rats by rescuing deficits in histone acetylation induced by increased HDAC activity in the amygdala. We have demonstrated that treatment with the HDAC inhibitor sodium butyrate blocks both the development and the expression of ethanol-induced behavioral sensitization in mice. In this context, converging evidence indicates that HDAC inhibitors could be useful in counteracting ethanol-induced gene regulations via epigenetic mechanisms, that is, HDAC inhibitors could affect different acetylation sites and may also alter the expression of different genes that could in turn counteract the effect of ethanol. Recent work in rodents has shown that systemic administration of pan HDAC class I and II inhibitors, TSA and N-hydroxy-N-phenyl-octanediamide [SuberoylAnilide Hydroxamic Acid] (SAHA), and of the more selective inhibitor (mainly HDAC1 and HDAC9) MS-275, decrease binge-like alcohol drinking in mice. SAHA selectively reduced ethanol operant self-administration and seeking in rats. Our previous study revealed that MS-275 strongly decreased operant ethanol self-administration in alcohol-dependent rats when administered 30 minutes before the session at the second day of injection. We also demonstrated that intra-cerebro-ventricular infusion of MS-275 increases acetylation of Histone 4 within the nucleus accumbens and the dorsolateral striatum, associated to a decrease in ethanol self-administration by about 75%. MS-275 also diminished both the motivation to consume ethanol (25% decrease), relapse (by about 50%) and postponed reacquisition after abstinence. Both literature and several of our studies strongly support the potential therapeutic interest of targeting epigenetic mechanisms in excessive alcohol drinking and strengthen theinterest of focusing on specific isoforms of histone deacetylases.

Converging evidence indicates that epigenetic mechanisms are involved in drug addiction, and that enzymes involved in chromatin remodeling may represent interesting targets in addiction treatment. No study has addressed whether histone deacetylase (HDAC) inhibitors (HDACi) can reduce excessive ethanol intake or prevent relapse in alcohol-dependent animals. Here, we assessed the effects of two HDACi, sodium butyrate (NaB) and MS-275, in the operant ethanol self-administration paradigm in dependent and non-dependent rats. To characterize some of the epigenetic mechanisms associated with alcohol dependence and NaB treatment, we measured the levels of histone H3 acetylation in different brain areas of dependent and non-dependent rats, submitted or not to NaB treatment. Our results demonstrated that (1) NaB and MS-275 strongly decreased excessive alcohol intake of dependent rats in the operant ethanol self-administration paradigm but not of non-dependent rats; (2) NaB reduced excessive drinking and prevented the escalation of ethanol intake in the intermittent access to 20% ethanol paradigm; and (3) NaB completely blocked the increase of ethanol consumption induced by an alcohol deprivation, thus demonstrating a preventive effect of NaB on relapse. The mapping of cerebral histone H3 acetylation revealed a hyperacetylation in the amygdala and cortical areas in dependent rats. Interestingly, NaB did not exacerbate the hyperacetylation observed in these regions, but instead restored it, specifically in cortical areas. Altogether, our results clearly demonstrated the efficacy of NaB in preventing excessive ethanol intake and relapse and support the hypothesis that HDACi may have a potential use in alcohol addiction treatment.

Adolescent alcohol binge drinking constitutes a major vulnerability factor to develop alcoholism. However, mechanisms underlying this susceptibility remain unknown. We evaluated the effect of adolescent binge-like ethanol intoxication on vulnerability to alcohol abuse in Sprague-Dawley rats. To model binge-like ethanol intoxication, every 2 days, rats received an ethanol injection (3.0 g/kg) for 2 consecutive days across 14 days either from postnatal day 30 (PND30) to 43 (early adolescence) or from PND 45 to PND 58 (late adolescence). In young adult animals, we measured free ethanol consumption in the two-bottle choice paradigm, motivation for ethanol in the operant self-administration task and both ethanol's rewarding and aversive properties in the conditioned place preference (CPP) and taste aversion (CTA) paradigms. While intermittent ethanol intoxications (IEI) during late adolescence had no effect on free-choice 10% ethanol consumption, we found that IEI during early adolescence promoted free-choice 10% ethanol consumption, enhanced motivation for ethanol in the self-administration paradigm and induced a loss of both ethanol-induced CPP and CTA in young adults. No modification in either sucrose self-administration or amphetamine-induced CPP was observed. As the nucleus accumbens (Nac) is particularly involved in addictive behavior, we analyzed IEI-induced long-term neuroadaptations in the Nac using c-Fos immunohistochemistry and an array of neurotransmission-related genes. This vulnerability to ethanol abuse was associated with a lower c-Fos immunoreactivity in the Nac and enduring alterations of the expression of Penk and Slc6a4, 2 neurotransmission-related genes that have been shown to play critical roles in the behavioral effects of ethanol and alcoholism.

Alcohol use disorder is a chronic and highly relapsing disorder, characterized by a loss of control over alcohol consumption and craving. Several studies suggest a key role of glutamate in this disorder. In recent years, the modulation of cystine/glutamate exchange via the x

As the contribution of cannabinoid (CB1) receptors in the neuroadaptations following chronic alcohol exposure is unknown, we investigated the neuroadaptations induced by chronic alcohol exposure on both NMDA and GABA(A) receptors in CB1-/- mice. Our results show that basal levels of hippocampal [(3)H]MK-801 ((1)-5-methyl-10,11-dihydro-5Hdibenzo[a,d]cyclohepten-5,10-imine) binding sites were decreased in CB1-/- mice and that these mice were also less sensitive to the locomotor effects of MK-801. Basal level of both hippocampal and cerebellar [(3)H]muscimol binding was lower and sensitivity to the hypothermic effects of diazepam and pentobarbital was increased in CB1-/- mice. GABA(A)alpha1, beta2, and gamma2 and NMDA receptor (NR) 1 and 2B subunit mRNA levels were altered in striatum of CB1-/- mice. Our results also showed that [(3)H]MK-801 binding sites were increased in cerebral cortex and hippocampus after chronic ethanol ingestion only in wild-type mice. Chronic ethanol ingestion did not modify the sensitivity to the locomotor effects of MK-801 in both genotypes. Similarly, chronic ethanol ingestion reduced the number of [(3)H]muscimol binding sites in cerebral cortex, but not in cerebellum, only in CB1+/+ mice. We conclude that lifelong deletion of CB1 receptors impairs neuroadaptations of both NMDA and GABA(A) receptors after chronic ethanol exposure and that the endocannabinoid/CB1 receptor system is involved in alcohol dependence.

Low to moderate perinatal ethanol exposure (PEE) may have disastrous consequences for the central nervous system resulting notably in permanent cognitive deficits. Learning and memory are mediated in the hippocampus by long-term potentiation (LTP) and long term depression (LTD), two forms of synaptic plasticity. PEE decreases LTP but also abnormally facilitates LTD (Kervern et al. ) through a presently unknown mechanism. We studied in rat hippocampus slice, the involvement of the chloride co-transporters NKCC1 and KCC2, in the role of GABA

A high density of opioid receptor-like 1 (ORL1) receptor (also referred to as NOP receptor) is found in limbic areas and in regions containing monoamines, which are implicated in emotional activity and physiopathology of depression and anxiety. We aimed at defining precisely the localization of ORL1 receptors in dorsal raphe nucleus, by means of a lesion strategy and autoradiographic studies. In control rats, [3H]nociceptin and nociceptin-stimulated [35S]GTPgammaS bindings were found to be correlated in several brain regions. We performed in rats a selective destruction of serotoninergic neurons by surgical stereotaxic injection of 5,7-dihydroxytryptamine (5,7-DHT) in dorsal raphe nucleus. This led to a marked decrease in serotonin contents in striata and frontal cortices (about -60%) and in autoradiographic [3H]citalopram binding in posterior regions. In dorsal raphe nucleus, [3H]nociceptin binding was decreased to the same extent as [3H]citalopram binding, whereas it was unchanged in the other regions studied. Nevertheless, in the dorsal raphe, nociceptin-stimulated [35S]GTPgammaS binding was decreased to a lesser extent than [3H]nociceptin binding in 5,7-DHT-lesioned rats. The ratio between nociceptin-stimulated [35S]GTPgammaS binding and [3H]nociceptin binding was significantly increased in 5,7-DHT-lesioned rats compared with controls in this region. These data demonstrate 1) that ORL1 receptors are located on serotoninergic neurons in the dorsal raphe nucleus and 2) that, after a lesion, the functionality of remaining ORL1 receptors appears to be up-regulated, which could correspond to a compensatory mechanism.

We performed an autoradiographic study of [ d -Ala 2 ,MePhe 4 ,Gly-ol 5 ]enkephalin (DAMGO)-sensitive [ 3 H]naloxone binding to μ-opioid receptors and of [ 3 H][ d -Pen 2 , d -Pen 5 ]enkephalin (DPDPE) binding to δ-opioid receptors in the rat brain after 4- or 21-day treatments with paroxetine, reboxetine and moclobemide to investigate the participation of these receptors in the adaptive mechanisms occurring during the delay of action of new generation antidepressants. Paroxetine increased μ-opioid receptor binding site density in cingulate and insular cortices, dorsal endopiriform nucleus (4 days) and olfactory tubercle (21 days) and decreased it in thalamus (21 days). Reboxetine increased it in amygdala (4 days), hippocampus and thalamus (21 days) and decreased it in dorsal raphe (4 days). Moclobemide increased it in hippocampus (4 days) and decreased it in anterior olfactory nucleus, frontal cortex, amygdala and hypothalamus (21 days). Moclobemide increased δ-opioid receptor binding site density in frontal cortex and amygdala (4 days) and decreased it in amygdala and colliculi (21 days). Opioid receptors displayed distinct patterns of adaptations in response to the three antidepressants studied.

30th Congress of the European-College-of-Neuropsychopharmacology (ECNP), Paris, FRANCE, SEP 02-05, 2017; International audience

Converging evidence indicates that epigenetic mechanisms are involved in drug addiction, and that enzymes involved in chromatin remodeling may represent interesting targets in addiction treatment. No study has addressed whether histone deacetylase (HDAC) inhibitors (HDACi) can reduce excessive ethanol intake or prevent relapse in alcohol-dependent animals. Here, we assessed the effects of two HDACi, sodium butyrate (NaB) and MS-275, in the operant ethanol self-administration paradigm in dependent and non-dependent rats. To characterize some of the epigenetic mechanisms associated with alcohol dependence and NaB treatment, we measured the levels of histone H3 acetylation in different brain areas of dependent and non-dependent rats, submitted or not to NaB treatment. Our results demonstrated that (1) NaB and MS-275 strongly decreased excessive alcohol intake of dependent rats in the operant ethanol self-administration paradigm but not of non-dependent rats; (2) NaB reduced excessive drinking and prevented the escalation of ethanol intake in the intermittent access to 20% ethanol paradigm; and (3) NaB completely blocked the increase of ethanol consumption induced by an alcohol deprivation, thus demonstrating a preventive effect of NaB on relapse. The mapping of cerebral histone H3 acetylation revealed a hyperacetylation in the amygdala and cortical areas in dependent rats. Interestingly, NaB did not exacerbate the hyperacetylation observed in these regions, but instead restored it, specifically in cortical areas. Altogether, our results clearly demonstrated the efficacy of NaB in preventing excessive ethanol intake and relapse and support the hypothesis that HDACi may have a potential use in alcohol addiction treatment.

We have compared the effects of an i.p. pretreatment with L-DOPA (200 mg/kg) associated with benserazide (25 mg/kg) on neurotoxic effects of either 6-hydroxydopamine (6-OHDA) (50 microg, 10 microl per mouse) or 1-methyl-4-phenylpyridinium (MPP+) (17.5 microg, 10 microl per mouse). The striatal dopamine (DA) content, the vesicular monoamine transporter (VMAT2) density, as well as the hypothalamic norepinephrine (NE) content were measured 8 days after treatments. The L-DOPA-benserazide pretreatment worsened by 65% the 6-OHDA-induced depletion in striatal DA. On the contrary, it reduced by 42% the MPP+-induced depletion in striatal DA and by 54% the MPP+-induced decrease in VMAT2 density. It was noticed that the L-DOPA-benserazide pretreatment did not modify the marked decrease in hypothalamic NE content induced by 6-OHDA.

International audience; Nociceptin/Orphanin FQ is the endogenous ligand of NOP receptor, formerly referred to as the Opioid Receptor-Like 1 receptor. We have previously shown that NOP receptors were located on serotonergic neurons in the rat dorsal raphe nucleus, suggesting possible direct interactions between nociceptin and serotonin in this region, which is a target for antidepressant action. In the present study, we investigated further the link between Selective Serotonin Reuptake Inhibitor (SSRI) antidepressant treatments and the nociceptin/NOP receptor system. Intraperitoneal administration of the SSRI citalopram induced an increase in NOP-receptor density, measured by autoradiographic [3H] nociceptin binding, in the rat dorsal raphe nucleus, from the first to the 21st day of treatment. This effect was also observed with other SSRIs (sertraline, fluoxetine), but not with two tricyclic antidepressants (imipramine, clomipramine) and was abolished by pre-treatment with para-chlorophenylalanine, an inhibitor of serotonin synthesis. Using microdialysis experiments, we demonstrated that NOP-receptor activation by infusion of nociceptin 10−6 M or 10−5 M increased the level of extracellular serotonin in the dorsal raphe nucleus. This effect was abolished by co-infusion of the NOP-receptor antagonist UFP 101. These results confirm the existence of reciprocal interactions between serotonin and nociceptin/NOP transmissions in the dorsal raphe nucleus.

International audience; A few clinical studies have shown that dual antidepressants (serotonergic (5-HT) and noradrenergic (NE) transporter inhibitors, SNRIs) may be effective in alcoholism treatment. We studied the effect of the dual antidepressant milnacipran on ethanol operant self-administration in acutely withdrawn ethanol-dependent and in -non-dependent Wistar rats, and used fluoxetine and desipramine to dissect both 5-HT and NE components, respectively, in the effect of milnacipran. Milnacipran was also tested for relapse after protracted abstinence and on ethanol-induced (1.0 g/kg) conditioned place preference in control rats and ethanol-induced locomotor sensitization in DBA/2J female mice. Milnacipran dose dependently (5-40 mg/kg) attenuated the increased ethanol self-administration observed during early withdrawal and was more potent in preventing reinstatement in dependent rats after protracted abstinence as compared with non-dependent rats. Desipramine and fluoxetine (10 mg/kg) blocked ethanol self-administration during early withdrawal, and recovery was delayed in dependent animals, indicating a potent effect. Ethanol self-administration was also reduced 1 day after treatment with desipramine and fluoxetine but not with milnacipran. Finally, milnacipran prevented ethanol-induced place preference in ethanol-naive rats and reduced the magnitude of ethanol-induced sensitization associated with a delayed induction in mice. Desipramine (20 mg/kg) countered sensitization development and reduced its expression at 1 week after treatment; fluoxetine (10 mg/kg) reduced sensitization expression. Thus, 5-HT and NE transmissions during sensitization expression may mediate the effect of milnacipran on sensitization induction. These results support that SNRIs may have a potential use in alcoholism treatment.

International audience; BACKGROUND: Ethanol addiction has been conceptualized as a progression from occasional, impulsive use to compulsive behavior. Ethanol-dependence is a chronic pathology with repeated cycles of withdrawal, craving, and relapse. Specific molecular and cellular mechanisms underlie these transition stages. METHODS: This review aimed at elucidating whether there are also adaptations in the pattern of brain regions responding to ethanol. This paper reviews the evidence in rodents for activation of specific brain regions, assessed by induction of IEG expression, following acute and chronic ethanol exposure. RESULTS: The review sheds light on the specific patterns of response in regions of the brain to different types of ethanol exposure and shows that activation of specific brain regions may occur in particular phases of the development of ethanol addiction. Some brain regions respond consistently following acute or chronic treatments or withdrawal: the prefrontal cortex; nucleus accumbens; lateral septum; hippocampus; perioculomotor urocortin-containing cells population (pIIIu), also known as Edinger-Westphal nucleus; central nucleus of the amygdala; and the paraventricular nucleus of hypothalamus. The two last brain areas are particularly activated by relapse-inducing stressors. It is of interest that the amygdala, hippocampus, and prefrontal cortex, which belong to the reward system, are activated by cue-induced relapse to ethanol self-administration in rodents and humans, while activation of these regions is reversed with anti-craving compounds. Following chronic exposure, IEG induction desensitizes while withdrawal reactivates these regions. DISCUSSION: Some responding regions are implicated in reward related processes (VTA, extended amygdala, hypothalamus, hippocampus, prelimbic cortex, ventral part of lateral septum) and some others in aversive-related processes (area postrema, nucleus of solitary tract). CONCLUSION: A better understanding of the neural circuits affected by ethanol and their adaptations during the development of ethanol addiction will provide new opportunities for developing appropriate therapies.

S31.1 ADOLESCENT INTERMITTENT ETHANOL-INDUCED HISTONE MODIFICATIONS AND DNA DEMETHYLATION: ROLE IN ANXIETY AND ALCOHOLISM {#article-title-2} Histone modifications and DNA methylation/demethylation regulate gene expression and play an important role in synaptic plasticity. We investigated the effects of adolescent intermittent ethanol (AIE) treatment on epigenetic modifications in the amygdala and on anxiety-like behaviors in adolescent and adult rats. The effects of AIE [2 g/kg, intraperitoneal; 2-days on/2-days off, 4 cycles (8 injections), postnatal days 28-41] on anxiety-like behaviors in adolescent rats was measured during withdrawal and effects of AIE exposure on anxiety-like and alcohol drinking behaviors at adulthood (postnatal day 92) were measured. Adolescent rats displayed anxiety-like behaviors after 24 hrs of ethanol withdrawal. At this time point, amygdaloid nuclear and cytosolic HDAC activity and levels of HDAC2 and HDAC4 were increased and histone (H3-K9) acetylation in the central (CeA) and medial amygdala (MeA) was decreased. Interestingly, in AIE adult rats nuclear HDAC activity and HDAC2 protein levels remained increased and histone acetylation remained decreased. We also found decreased histone H3 acetylation in promoters of Arc, NPY, and various BDNF exons in the amygdala of AIE compared with control (adolescent intermittent saline) adult rats. AIE produced a reduction in dendritic spines in the CeA and MeA and decreased mRNA levels of GADD45g, but not GADD45a or GADD45b in the amygdala of adult rats. AIE induced anxiety-like and alcohol drinking behaviors at adulthood were attenuated by treatment with trichostatin A. These results suggest that AIE induced epigenetic changes in the amygdala may play a crucial role in anxiety-like and alcohol-drinking behaviors at adulthood (supported by NADIA grant from NIH-NIAAA). # S31.2 IS THERE A FUTURE FOR USING HDAC INHIBITORS IN ALCOHOL DEPENDENCE? {#article-title-3} Emerging evidence suggests that epigenetic alterations to the genome, including DNA methylation and histone modifications, are important mechanisms underlying alcohol addiction. With the new field of epigenetics, there is now the opportunity to integrate the role of the epigenome not only in the short-term effects of alcohol but also in the enduring neuro-adaptations caused by chronic use of alcohol. The epigenetic modifications may be part of the neuro-adpatations occurring during the transition from the controlled intake to the loss of control and may explain how alcohol can have such a persistent effect on brain gene expression and functioning. There are now accumulating data showing that pharmacological tools targeting enzymes involved in epigenetic modifications may be useful in reducing or preventing some behavioral responses to alcohol. In the present work we have investigated the effects of different HDAC inhibitors (sodium butyrate, trichostatine A, MS-275 and sirtinol) on alcohol intake in rats with several paradigms, i.e. operant 10% ethanol self-administration, intermittent 20% ethanol intake and alcohol deprivation effect. We have also investigated the effects of HDAC inhibitors on excessive alcohol intake in alcohol-dependent animals and explored associated modifications in the brain levels of acetylated histone H3. Finally we tested the effects of HDAC inhibitors on ethanol-induced behavioral locomotor sensitization in mice and analyzed alterations in striatal gene expression and both HDAC and HAT activities. Altogether our results show that HDAC inhibitor can reduce and / or prevent several behavioral effects of alcohol and that this effect of HDAC inhibitors can be due, at least in part, to epigenetic mechanism. # S31.3 GENETIC AND ENVIRONMENTAL RISKS FOR PATTERNS OF ALCOHOL USE FROM ADOLESCENCE THROUGH EARLY ADULTHOOD {#article-title-4} Purpose. Early and heavy initiation of alcohol use is a risk for later abuse and health problems; hence, identifying contributors to youth alcohol use is a central goal. This paper seeks to delineate trajectories of alcohol use and abuse from early adolescence through early adulthood, and identify environmental and genetic risk factors contributing to problematic patterns of early alcohol use. We compare four leading explanations for problematic alcohol use: social norms, social controls, stress, and genetic predispositions. Methods. Data were drawn from a nationally representative study of American youth (Add Health), following 20,745 youth from early adolescence through early adulthood. Youth reported on alcohol use and inebriation. Youth, parents, peers, and school administrators reported on social norms (parent drinking, peer drinking, schoolmate drinking), social controls (parental supervision, monitoring, school punishment), and stressful life events. A genetic risk score was calculated using DNA data on three dopaminergic polymorphisms (DRD4, DAT1, MAOA). Results. Trajectory analysis found five patterns of alcohol use from early adolescence through early adulthood, delineating abstainers, low users, early declining, early increasing, and late increasing patterns of alcohol use. Analyses identified four trajectories of inebriation: abstainers, low users, early declining, and increasing. Multilevel multinomial logistic regression models predicted patterns of drinking and inebriation, finding significant effects of social norms, social control, and life stressors for males' patterns of alcohol use and inebriation. For females, social norms, life stressors, and genetic risks were significant predictors of alcohol use and inebriation. Models found little evidence of gene by environment interactions. # S31.4 PRENATAL ETHANOL-INDUCED HYPERMETHYLATION OF PROOPIOMELANOCORTIN GENE TRANSMITS THROUGH GERMLINE {#article-title-5} We have recently shown that alcohol exposure during the fetal period permanently suppresses the expression of stress controlling beta-endorphin due to hypermethylation of it's precursor POMC gene. In this study, we determined the mechanism by which the POMC gene is hypermethylated. Additionally, transgenerational studies were conducted to evaluate the germline-transmitted effect of alcohol. We found that fetal alcohol exposure decreased the levels of the activation histone marks H3K4, aceH3K9 and pH3S10 in POMC neurons, and increased the repressive histone mark H3K9. The fetal alcohol exposure also altered the protein levels and gene expression of POMC, Set7/9, CBP, HDAC2, G9a, Setdb1, MeCP2 and Dnmt1 except for Dnmt3a. Alcohol treatment also reduced the activation mark H3K4me3 along Exon 3 of POMC gene. Suppression of histone deacetylation and DNA methylation normalized POMC expression and functional abnormalities. Gestational choline supplementation also reversed alcohol-induced alteration in histone-modifying and DNA-methylating enzymes and normalized POMC gene promoter methylation, POMC gene expression and β-endorphin peptide production in POMC neurons. Fetal alcohol-induced POMC gene methylation, expression and functional defects persisted in the F2 and F3 male but not in female germline. Additionally, the hypermethylated POMC gene was detected in sperms of fetal alcohol exposed F1 offspring that was transmitted through F3 generation via male germline. Overall, these research findings collectively demonstrate that epigenetic changes contribute to the effects of fetal alcohol exposure on POMC gene expression as well as the perpetuation of abnormal POMC neuronal functions through subsequent generations via the male. (Supported by NIH Grant AA016695 and R37 AA08757).

Opioid-receptor-like I (ORLI) receptors, ORLI mRNA and nociceptin are particularly abundant in the limbic system and in central monoaminergic areas, brain regions involved in mood regulation and response to antidepressants. To analyse whether ORLI receptors adaptations occur during the first 3 weeks of an antidepressant treatment, we administered paroxetine to rats (10 mg/kg, i.p., once a day) for 4, 7,14 or 21 days. A significant increase (22-50%) in [3H]nociceptin binding sites density appeared specifically in the dorsal raphe nucleus after 4, 7 or 21 days of treatment, whereas no change was observed at any time in any other brain regions studied. These data constitute the first evidence of a modulation of ORLI receptors by an antidepressant treatment.

To date, very little information is available about the regulation of vesicular monoamine transporter in central serotonergic regions. The expression of the vesicular monoamine transporter 2 (VMAT2) has been studied in the serotonergic system of the rat brain after an 18 day treatment with the serotonin selective-reuptake inhibitor paroxetine (10 mg/kg, i.p., once daily). This treatment, while increasing serotonergic transmission, did not modify either VMAT2 mRNA expression or 3 H-dihydrotetrabenazine binding site density in any of the studied regions. These results suggest that VMAT2 regulation in the central serotonergic system is not involved in the mechanism of action of antidepressants. In addition, a single administration of reserpine (5 mg/kg, s.c.), while blocking the vesicular monoamine uptake function, had no effect on VMAT2 immunoreactivity in the dorsal raphe nucleus 2 or 30 days after injection. It is concluded that neither a reduction (reserpine) nor an enhancement (paroxetine) of the serotonin transmission induces VMAT2 regulation in serotonergic system in the rat brain. © 2000 Elsevier Science Ltd. All rights reserved.

Les préparations à base de mélatonine sont de plus en plus prescrites chez les enfants ayant des troubles du sommeil. Au sein de la population pédiatrique, de nombreux troubles du sommeil sont rapportés dans la littérature scientifique, notamment chez les enfants atteints de troubles du spectre autistique (TSA) et chez les enfants atteints du trouble déficitaire de l'attention avec ou sans hyperactivité (TDAH) ; leur prise en charge est donc essentielle. Les interventions comportementales et d'hygiène du sommeil doivent être instaurées en première ligne. Dans ce travail, l'efficacité et l'innocuité d'une supplémentation en mélatonine chez les enfants sans pathologie avérée, chez les enfants atteints de TSA et chez les enfants atteints de TDAH ont été étudiées et validées, notamment dans le syndrome de retard de phase du sommeil.

L'alcool représente un enjeu considérable de santé publique dans l'ensemble de l’Europe et en France en particulier. Les récentes recherches ont permis de mettre en évidence que l'éthanol était entre autre, un perturbateur épigénétique. Parmi les différents mécanismes épigénétiques perturbés par l'éthanol, l'acétylation des protéines histones, que l'éthanol favorise, est la mieux documentée. Cependant, la compréhension des mécanismes par lesquels l'éthanol est un perturbateur épigénétique reste à parfaire. C'est dans ce but que nous avons étudié la molécule EBJD9, supposée d'être un activateur HDAC. Nos résultats mettent en lumière qu’EBJD9 induit in vitro une augmentation de l'acétylation H4K12 et une augmentation de l'activité HDAC totale, et induit in vivo une hausse de la consommation d'éthanol chez des rats qui buvaient spontanément peu d’alcool sans montrer d'évolution de la consommation d'éthanol chez des rats qui en buvaient spontanément beaucoup. Cela nous apparaît tout à fait pertinent dans la mesure où les iHDACs ont la propriété de diminuer la consommation d’alcool dans plusieurs modèles animaux. Les résultats préliminaires (n=3) de la cytométrie en flux, montrent que ces deux groupes de rats diffèrent par leurs niveaux d’acétylation Ac-H4K12. Dans le cortex préfrontal, les bons buveurs présentent une plus forte expression de HDAC2 et une moindre expression d’Ac-H4K12 par rapport aux rats mauvais buveurs, tandis qu’ils présentent une plus faible expression de la sous unité GluN2B du récepteur NMDA. Dans le noyau accumbens, nous observons le même profil pour HDAC2 et Ac-H4K12, mais l’expression de la sous unité GluN2B du récepteur NMDA est plus forte pour les bons buveurs. Il existe également une tendance d’EBJD9 à « normaliser » Ac-H4K12 dans le cortex pré-frontal et le noyau accumbens dans les deux groupes de rats sans modifier l’expression de HDAC2. Nous avons précédemment montré au laboratoire qu’une augmentation de l’expression de HDAC2 est associée à une augmentation de l’expression de la sous unité GluN2B par action sur son promoteur. Ici nous observons avec EBJD9 une expression de GluN2B dans le cortex préfrontal et le noyau accumbens qui évolue dans le sens inverse à celui attendu par l’hypothèse qui voudrait qu’EBJD9 module l’activité HDAC2. Dans la mesure où EBJD9 ne module pas HDAC2, nous proposons l’hypothèse qu’EBJD9 développe son effet sur Ac-H4K12 via une action sur une enzyme HDAC différente de HDAC2. Ensemble, ces résultats permettent de dire qu’EBJD9 se comporte comme un activateur HDAC, qui ne cible pas HDAC2. Ce travail permet d’enrichir les connaissances actuelles sur les activateurs HDACs dont l'étude est encore très récente. La compréhension de leurs mécanismes d'action pourrait nous en apprendre beaucoup sur les mécanismes d'action de l'éthanol, reconnu comme étant lui-même un activateur HDAC.