Epigenetic drugs and psychedelics as emerging therapies for alcohol use disorder: insights from preclinical studies

Alcohol use disorder (AUD) is a public health issue that affects millions of people worldwide leading to physical, mental and socio-economic consequences. While current treatments for AUD have provided relief to individuals, their effectiveness on the long term is often limited, leaving a number of affected individuals without sustainable solutions. In this review, we aim to explore two emerging approaches for AUD: psychedelics and epigenetic drugs (i.e., epidrugs). By examining preclinical studies, different animal species and procedures, we delve into the potential benefits of each of these treatments in terms of addictive behaviors (alcohol drinking and seeking, motivation to drink alcohol and prevention of relapse). Because psychedelics and epidrugs may share common and complementary mechanisms of action, there is an exciting opportunity for exploring synergies between these approaches and their parallel effectiveness in treating AUD and the diverse associated psychiatric conditions.

Alcohol-related cognitive impairments in patients with and without cirrhosis

AIMS

up to 80% of patients with alcohol use disorder display cognitive impairments. Some studies have suggested that alcohol-related cognitive impairments could be worsened by hepatic damage. The primary objective of this study was to compare mean scores on the Brief Evaluation of Alcohol-Related Neurocognitive Impairments measure between alcohol use disorder patients with (CIR+) or without cirrhosis (CIR-).

METHODS

we conducted a prospective case-control study in a hepatology department of a university hospital. All patients were assessed using the Evaluation of Alcohol-Related Neuropsychological Impairments test.

RESULTS

a total of 82 patients (50 CIR+, 32 CIR-) were included in this study. CIR- patients were significantly younger than CIR+ patients (respectively, 45.5 ± 6.8 vs 60.1 ± 9.0; P < .0001). After adjusting for age and educational level, the mean Evaluation of Alcohol-Related Neuropsychological Impairments total scores in the CIR+ group were significantly lower than in the group of CIR- patients (14.1 ± 0.7 vs 7.8 ± 0.4, respectively, P < .0001). The mean subscores on delayed verbal memory, alphabetical ordination, alternating verbal fluency, visuospatial abilities, and ataxia subtests were also significantly lower in the CIR+ than in the CIR- group (respectively, 1.9 ± 0.2 vs 2.8 ± 0.2; 1.8 ± 0.2 vs 2.7 ± 0.2; 2.2 ± 0.2 vs 3.6 ± 0.2; 0.7 ± 0.2 vs 1.6 ± 0.2; 0.7 ± 0.2 vs 3.1 ± 0.2; P < .0001 for all comparisons).

CONCLUSIONS

in the present study, alcohol use disorder patients with cirrhosis presented more severe cognitive impairments than those without cirrhosis. Longitudinal studies are needed to investigate how cirrhosis can influence cognitive impairments.

Could reasons for admission help to screen unhealthy alcohol use in emergency departments? A multicenter French study

Background

Many patients admitted to general emergency departments (EDs) have a pattern of drinking that could lead to future alcohol-related complications. However, it is often difficult to screen these patients in the context of emergency. The aim of this study is to analyze whether reasons for admission could help to screen patients who have an unhealthy alcohol use.

Method

Patients were recruited among six public hospital ED in France, between 2012 and 2014. During a one-month period in each hospital, anonymous questionnaires including sociodemographic questions, AUDIT-C and RAPS4-QF were administered to each patients visiting the ED. The reason for admission of each patient was noted at the end of their questionnaire by the ED practitioner.

Results

Ten thousand Four hundred twenty-one patients were included in the analysis. Patients who came to the ED for injuries and mental disorders were more likely to report unhealthy alcohol use than non-harmful use or no use. Among male patients under 65 years old admitted to the ED for a mental disorder, 24.2% drank more than four drinks (40 g ethanol) in typical day at least four time a week in the last 12 months. Among these patients, 79.7% reported daily or almost daily heavy episodic drinking (HED, 60 g ethanol), and all were positive on the RAPS4-QF.

Conclusion

This study highlights that unhealthy alcohol use is frequent among ED patients and particularly among those who come for injuries or mental disorders. Men under 65 years old with a mental disorder require special attention because of their increased prevalence of daily or almost daily HED.

Brain-derived neurotrophic factor Val66Met polymorphism moderates the relationship between impulsivity, negative emotions, and binge drinking intensity in university students

Studies on the genetic factors involved in binge drinking (BD) and its associated traits are very rare. The aim of this cross-sectional study was to investigate differences in the association between impulsivity, emotion regulation and BD in a sample of young adults according to the rs6265/Val66Met variant in the brain-derived neurotrophic factor (BDNF) gene, a well-known candidate gene in alcohol use disorders. We recruited 226 university students (112 women), aged between 18 and 25 years old, from two centers in France. The participants completed measures related to alcohol consumption, depression severity, state anxiety levels, impulsivity (UPPS-P), and difficulties in emotion regulation [Difficulty in Emotion Regulation Scale (DERS)]. The relationship between the BD score and the clinical characteristics in the BDNF genotype groups was assessed by partial correlation analyses and moderation analyses. The partial correlation analyses showed that, in the Val/Val genotype group, the BD score was positively related to UPPS-P Lack of Premeditation and Sensation Seeking scores. In the Met carriers group, the BD score was positively related to UPPS-P Positive Urgency, lack of Premeditation, lack of Perseverance and Sensation Seeking scores and to Clarity score of the DERS. Moreover, the BD score was positively associated with depression severity and state anxiety scores. The moderation analyses revealed that BDNF Val/Met genotype moderated the relationship between several clinical variables and BD. The results of the present study support the hypothesis of common and specific vulnerability factors regarding impulsivity and emotion regulation difficulties associated with BD according to this BDNF rs6265 polymorphism.

A new statistical model for binge drinking pattern classification in college-student populations

Background

Binge drinking (BD) among students is a frequent alcohol consumption pattern that produces adverse consequences. A widely discussed difficulty in the scientific community is defining and characterizing BD patterns. This study aimed to find homogenous drinking groups and then provide a new tool, based on a model that includes several key factors of BD, to assess the severity of BD regardless of the individual's gender.

Methods

Using the learning sample (N1 = 1,271), a K-means clustering algorithm and a partial proportional odds model (PPOM) were used to isolate drinking and behavioral key factors, create homogenous groups of drinkers, and estimate the probability of belonging to these groups. Robustness of our findings were evaluated with Two validations samples (N2 = 2,310, N3 = 120) of French university students (aged 18-25 years) were anonymously investigated via demographic and alcohol consumption questionnaires (AUDIT, AUQ, Alcohol Purchase Task for behavioral economic indices).

Results

The K-means revealed four homogeneous groups, based on drinking profiles: low-risk, hazardous, binge, and high-intensity BD. The PPOM generated the probability of each participant, self-identified as either male or female, to belong to one of these groups. Our results were confirmed in two validation samples, and we observed differences between the 4 drinking groups in terms of consumption consequences and behavioral economic demand indices.

Conclusion

Our model reveals a progressive severity in the drinking pattern and its consequences and may better characterize binge drinking among university student samples. This model provides a new tool for assessing the severity of binge drinking and illustrates that frequency of drinking behavior and particularly drunkenness are central features of a binge drinking model.

[Alcohol consumption and high blood pressure]

ALCOHOL CONSUMPTION AND HIGH BLOOD PRESSURE. Cardiovascular disease is the second leading cause of alcohol-attributable mortality after cancer. The impact of alcohol consumption on blood pressure and the risk of cardiovascular pathologies are still largely underestimated by the general population and health professionals. However, numerous studies have demonstrated a dose-dependent increase in blood pressure, even at consumption levels close to the consumption guidelines (two drinks i.e. 20g per day). The alleged protective effects of low consumption levels are not confirmed, even in women. The binge drinking pattern has a particularly strong impact on blood pressure. The increase in blood pressure due to alcohol is reversible after reduction of consumption. Several pathophysiological mechanisms have been proposed to explain the hypertensive effects of alcohol. The screening of alcohol consumption by health professionals remains largely insufficient, especially in France, even in hypertensive subjects, although intervention is effective. It seems particularly important to reinforce the training of health professionals and the screening of alcohol consumption for primary prevention and also for secondary prevention when hypertension is already established. Scientific societies and federations should reinforce communication on the risks associated with alcohol consumption.

Sex-related differences in the efficacy of Baclofen enantiomers on self-administered alcohol in a binge drinking pattern and dopamine release in the core of the nucleus accumbens

Introduction: Clinical studies on the effectiveness of Baclofen in alcohol use disorder (AUD) yielded mixed results possibly because of differential effects of the enantiomers and sex-related differences. Here we examined the effect of the different Baclofen enantiomers on alcohol intake and on evoked dopamine release in the core of the nucleus accumbens (NAcc) in male and female Long Evans rats.

Methods: Rats were trained to chronically self-administer 20% alcohol solution in daily binge drinking sessions and were treated with the different forms of Baclofen [RS(±), R(+) and S(−)]. The effects on the evoked dopamine release within the core of the nucleus accumbens were measured in brain slices from the same animals and the alcohol naïve animals using the fast scan cyclic voltammetry technique.

Results: RS(±)-Baclofen reduced alcohol intake regardless of sex but more females were non-responders to the treatment. R(+)-Baclofen also reduced alcohol intake regardless of sex but females were less sensitive than males. S(−)-Baclofen did not have any effect on average but in some individuals, especially in the females, it did increase alcohol intake by at least 100%. There were no sex differences in Baclofen pharmacokinetic but a strong negative correlation was found in females with a paradoxical effect of increased alcohol intake with higher blood Baclofen concentration. Chronic alcohol intake reduced the sensitivity to the effect of Baclofen on evoked dopamine release and S(−)-Baclofen increased dopamine release specifically in females.

Discussion: Our results demonstrate a sex-dependent effect of the different forms of Baclofen with no or negative effects (meaning an increase in alcohol self-administration) in subgroup of females that could be linked to a differential effect on dopamine release and should warrant future clinical studies on alcohol use disorder pharmacotherapy that will deeply analyze sex difference.

Sex-specific decision-making impairments and striatal dopaminergic changes after binge drinking history in rats

Binge drinking (BD) is a harmful behavior for health and is a predictive factor for the development of alcohol addiction. Weak decision-making (DM) capacities could play a role in the vulnerability to BD which in turn would lead to DM impairments, thus perpetuating BD. Longitudinal preclinical studies are however lacking and necessary to understand this complex relationship. Both DM and BD are influenced by sex and involve dopamine release in the core of the nucleus accumbens, a central mechanism regulated by dopamine D2/3 autoreceptors. In this context, we used an operant self-administration procedure of BD in male and female rats, and longitudinally assessed DM capacity, memory and anxiety-like behavior. To better understand the mechanisms potentially involved in the relationship between DM and BD, ex vivo dopamine transmission was assessed short term after the end of the binge exposure in the core of the nucleus accumbens (NAc) using the fast-scan cyclic voltammetry (FSCV) technique and the D2/3 agonist quinpirole. We found important basal sex differences in DM, with female rats showing better performances at baseline. Choice processes were impaired exclusively in males after BD history, associated with a decrease in impulse control in both sexes, while memory and anxiety-like behavior were not affected. Our neurobiological results demonstrate that BD did not affect basal dopamine signaling in the NAc core, regardless of the sex, but reveal changes in the sensitivity to the inhibitory effects of quinpirole in females. DM impairments were neither associated with changes in basal dopamine signaling nor pre-synaptic D2 activity. Overall, our findings show that BD affects both DM processes and dopamine transmission in the core of the NAc in a sex-related manner, further suggesting that these effects may play a role in the vicious cycle leading to BD perpetuation and the early onset of AUD. Our results may inform novel strategies for therapeutic and prevention interventions.

[Binge drinking in the young population: Lost memory after initial ethanol exposure via neuroinflammation and epigenetic]

Binge drinking (BD) in young adults/adolescents can lead to cognitive deficits in the adult probably through neuroinflammation and epigenetic. However, the mode of action of alcohol during the initial exposure is less known while it may be the origin of the deficits seen in adults. Recent studies in adolescent rat hippocampus revealed that loss of memory occurred since the very first exposure to BD with similar mechanisms than those highlighted for longer alcohol exposure. Thus, initiation to BD in the young is responsible for cognitive deficits that will be probably entertained by repeated BD behavior. These kind of data may serve to reinforce the prevention campaigns towards the young population who practice BD.

Changes in Alcohol Consumption among Users of an Internet Drug Forum during a COVID-19 Lockdown

BACKGROUND

The aim of the present study was to assess the frequency and clinical correlates of users of an Internet drug forum who changed their alcohol use during the March-May 2020 COVID-19 lockdown in France.

METHODS

An anonymous Internet-based cross-sectional survey during the COVID-19 lockdown was used via messages on a French Internet drug forum. Participants reported any increase in their alcohol consumption during the lockdown. Alcohol craving and depressive/anxiety symptoms were assessed using the Obsessive and Compulsive Drinking scale (OCDS) and Hospital Anxiety and Depression scale (HADS).

RESULTS

Of 1310 respondents, 974 (79% of 1270) participants reported alcohol use before lockdown. During the lockdown, 405 participants (41.6%; IC95 (38.5-44.7)) reported an increase. Odds of an increase in alcohol consumption was higher for those with HADS scores higher than 7 (aOR: 2.19; p = 0.00002), OCDS scores greater than 7 (aOR: 3.50; p < 0.001), and daily psychostimulant use (aOR: 1.85; p = 0.002).

CONCLUSIONS

Users of an Internet drug forum who reported high levels of depressive symptoms, high levels of alcohol craving, and the use of psychostimulants were more likely to increase alcohol consumption during a COVID-19 lockdown.

Plasma tau, NfL, GFAP and UCHL1 as candidate biomarkers of alcohol withdrawal-associated brain damage: A pilot study

In this translational study, we investigated the plasma tau protein, neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCHL1), which are established biomarkers of neurological injury, as predictive biomarkers of alcohol withdrawal-associated brain toxicity. In the clinical study, patients with severe alcohol use disorder (AUD) on D1 of hospitalization for alcohol cessation (AC) (N = 36) were compared to severe AUD patients with at least 3 months of abstinence (N = 16). Overall, patients were 40 men (76.9%), aged 49.8 years [SD ±9.9]. Tau, NfL, GFAP and UCHL1 levels were measured using SIMOA and analysed with a quasipoisson regression model adjusted for age and sex. The NfL level was higher in the AC group (p = 0.013). In the AC group, the tau (p = 0.021) and UCHL1 (p = 0.021) levels were positively associated with the dose of diazepam per weight, and the tau (p = 0.045), NfL (p = 4.9 × 10^-3 ) and UCHL1 (p = 0.036) levels were higher in the presence of signs of Wernicke's encephalopathy (n = 9). In the preclinical study, NfL and GFAP levels were assessed in the alcohol deprivation effect (ADE) procedure (N = 17) and control Wistar rats (N = 15). Furthermore, ADE rats were prospectively assessed: after 24 h (T1) and 3 weeks of AC (T2) (paired-samples Wilcoxon and Mann-Whitney tests). The NfL level was higher in the ADE model than in the control rats at both T1 and T2 (p = 0.033 and p = 1.3 × 10^-3 ) and higher at T2 than at T1 (p = 0.040). Plasma tau, NfL and UCHL1 are potential biomarkers of brain suffering during alcohol withdrawal.

[Alcohol and atrial fibrillation]

Atrial fibrillation (AF) is the most common heart rhythm disorder, with an increasing prevalence, currently estimated at 3 % of the world population. It has long been well known, as the holiday heart syndrome, that acute alcohol consumption (binge drinking) may trigger an episode of AF, most often benign, during or immediately after consumption. Meta-analyses of observational studies have clearly shown a significant association between a high level of alcohol consumption and the risk of AF. According to the studies included in meta-analyses, the conclusions may differ regarding the association between low and moderate levels of alcohol consumption and the risk of AF. The association probably only exists from a level of consumption of at least one drink per day. Heavy alcohol consumption appears to increase the risk of complications in patients with AF, while light or moderate alcohol consumption does not. The causal nature of the relationship between alcohol consumption and AF cannot currently be confirmed or denied, given the contradictory results of Mendelian randomization studies published to date. However, in patients diagnosed with AF, the recommendation to abstain from alcohol, resulting in a strong reduction in consumption, made it possible to significantly reduce the recurrence of AF episodes.

Anti-inflammatory drugs prevent memory and hippocampal plasticity deficits following initial binge-like alcohol exposure in adolescent male rats

RATIONALE

Binge drinking during adolescence impairs learning and memory on the long term, and many studies suggest a role of neuroinflammation. However, whether neuroinflammation occurs after the very first exposures to alcohol remains unclear, while initial alcohol exposure impairs learning for several days in male rats.

OBJECTIVES

To investigate the role of neuroinflammation in the effects of only two binge-like episodes on learning and on neuronal plasticity in adolescent male rat hippocampus.

METHODS

Animals received two ethanol i.p. injections (3 g/kg) 9 h apart. Forty-eight hours later, we recorded long-term depression (LTD) and potentiation (LTP) in CA1 area of hippocampus slices. In isolated CA1, we measured immunolabelings for microglial activation and Toll-like receptor 4 (TLR4) and mRNA levels for several cytokines.

RESULTS

Forty-eight hours after the two binges, rats performed worse than control rats in novel object recognition, LTD was reduced, LTP was increased, and excitatory neurotransmission was more sensitive to an antagonist of the GluN2B subunit of the NMDA receptor. Exposure to ethanol with minocycline or indomethacin, two anti-inflammatory drugs, or with a TLR4 antagonist, prevented all effects of ethanol. Immunolabelings at 48 h showed a reduction of neuronal TLR4 that was prevented by minocycline pretreatment, while microglial reactivity was undetected and inflammatory cytokines mRNA levels were unchanged.

CONCLUSION

Two binge-like ethanol exposures during adolescence in rat involved neuroinflammation leading to changes in TLR4 expression and in GluN2B functioning inducing disturbances in synaptic plasticity and cognitive deficits. Anti-inflammatory drugs are good candidates to prevent brain function and memory deficits induced by few binge-drinking episodes.

One-month alcohol abstinence national campaigns: a scoping review of the harm reduction benefits

Over the last decade, one-month alcohol abstinence campaigns (OMACs) have been implemented within the general population in an increasing number of countries. We identified the published studies reporting data on OMACs to explore the following aspects: profile of participants, rates and factors associated with the completion of the abstinence challenge, and outcomes and harm reduction benefits in participating in the challenges. We screened 322 records, including those found in the grey literature, and reviewed 6 studies and 7 Dry July Annual Reports. Compared to non-participating alcohol users, participants were more likely to be female, have a higher income, and a higher level of education. They were heavier drinkers and were more concerned by the consequences of alcohol on health and by their health in general. Participants who achieved the one-month abstinence challenge were lower drinkers and more likely to have registered on the campaign-related Internet communities. Both successful and unsuccessful participants frequently reported health benefits, including sleep improvement and weight loss. Successful participants were more likely to durably change their alcohol drinking habits. Overall, OMACs provide short- or mid-term harm reduction benefits for both successful and unsuccessful participants. Findings were limited by the paucity of studies, their observational nature, and heterogeneity in the features of the different national campaigns, which would probably gain in enhanced internationalization.

Astrogliosis and compensatory neurogenesis after the first ethanol binge drinking-like exposure in the adolescent rat

BACKGROUND

Multiple ethanol binge drinking-like exposures during adolescence in the rat induce neuroinflammation, loss of neurogenesis, and cognitive deficits in adulthood. Interestingly, the first ethanol binge drinking-like exposure during adolescence also induces short- term impairments in cognition and synaptic plasticity in the hippocampus though the cellular mechanisms of these effects are unclear. Here, we sought to determine which of the cellular effects of ethanol might play a role in the disturbances in cognition and synaptic plasticity observed in the adolescent male rat after two binge-like ethanol exposures.

METHODS

Using immunochemistry, we measured neurogenesis, neuronal loss, astrogliosis, neuroinflammation, and synaptogenesis in the hippocampus of adolescent rats 48 h after two binge-like ethanol exposures (3 g/kg, i.p., 9 h apart). We used flow cytometry to analyze activated microglia and identify the TLR4-expressing cell types.

RESULTS

We detected increased hippocampal doublecortin immunoreactivity in the subgranular zone (SGZ) of the dentate gyrus (DG), astrogliosis in the SGZ, and a reduced 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 or 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 48 h after the first binge-like ethanol exposures are associated with hippocampal structural plasticity, astrogliosis, and decreased neuronal TLR4 expression, but not with microglia reactivity.

Sugar, a powerful substitute for ethanol in ethanol postdependent rats: Relevance for clinical consideration?

Sugar has been shown to be a powerful substitute for drugs in preclinical studies on addiction. However, the link between sugar intake and alcohol use disorder (AUD) is poorly understood. We assessed the influence of sucrose on ethanol drinking in both nondependent (ND) and dependent (D) Long-Evans rats during acute withdrawal using the postdependent state model. Ethanol (10%-40%) and sucrose (1%-4%) solutions were offered in an operant paradigm either independently or concurrently under ratio schedules of reinforcement. We showed that D rats displayed an enhanced motivation for both 10% ethanol solution (10E) and 4% sucrose solution (4S) as compared with ND rats, and a clear preference for 4S was observed in both groups. During acute withdrawal, D rats showed a strong motivation for 30% ethanol (30E), even when adulterated with quinine, but still preferred 4S despite the fact that a high level of negative reinforcement could be expected. However, when a premix solution (30E4S) was offered concurrently with 4S, the preference for 4S was lost in D animals, which consumed as much premix as 4S, whereas ND animals displayed preference for 4S. Altogether, those results suggest that reinforcing properties of sucrose surpass those of ethanol in D rats under acute withdrawal, which indicates that sugar is a powerful substitute for ethanol. Our results suggest that craving for sugar may be increased in AUD patients during withdrawal and raise the issue of dependence transfer from alcohol to sugar.

Interstrain differences in voluntary binge-like drinking behavior and in two acute ethanol injections-induced synaptic plasticity deficits in rats

Propensity to drink alcohol and to initiate binge drinking behavior is driven by genetic factors. Recently, we proposed an original animal model useful in the study of voluntary binge-like drinking (BD) in outbred Long-Evans rats by combining intermittent access to 20% ethanol in a two-bottle choice (IA2BC) paradigm to 15-min daily sessions of 20% ethanol operant self-administration. We sought to compare three strains of outbred rats (Long-Evans, Sprague-Dawley, and Wistar) in our BD model. Because we found different propensity to BD between strains, we also sought to test interstrain differences using another procedure of two acute ethanol exposures known to alter long-term depression of hippocampal synaptic plasticity. Our results demonstrate that in both IA2BC and operant procedures, the Long-Evans strain consumed the highest, Wistar the lowest amount of ethanol, and the Sprague-Dawley was intermediate. Long-Evans rats were also the fastest consuming with the shortest time to reach 50% of their maximum consumption in 15 min. When we tested the acute effects of ethanol, long-term depression in hippocampus was abolished specifically in Long-Evans rats with no impact in the two other strains. Thus, our study reveals that the Long-Evans strain is the ideal strain in our recently developed animal model useful in the study of BD. In addition, with the other paradigm of forced acute ethanol exposure, the Long-Evans strain displayed an increase in sensitivity to the deleterious effect of BD on hippocampal synaptic plasticity. Further studies are needed in order to investigate why Long-Evans rats are more prone to BD.

Sex difference in the vulnerability to hippocampus plasticity impairment after binge-like ethanol exposure in adolescent rat: Is estrogen the key?

Binge drinking during adolescence induces memory impairments, and evidences suggest that females are more vulnerable than males. However, the reason for such a difference is unclear, whereas preclinical studies addressing this question are lacking. Here we tested the hypothesis that endogenous estrogen level (E2) may explain sex differences in the effects of ethanol on hippocampus plasticity, the cellular mechanism of memory. Long-term depression (LTD) in hippocampus slice of pubertal female rats was recorded 24 h after two ethanol binges (3 g/kg, i.p., 9 h apart). Neither the estrous cycle nor ethanol altered LTD. However, if ethanol was administered during proestrus (i.e., at endogenous E2 peak), LTD was abolished 24 h later, whereas NMDA-fEPSPs response to a GluN2B antagonist increased. The abolition of LTD was not observed in adult female rats. Exogenous E2 combined with ethanol replicated LTD abolition in pubertal, prepubertal female, and in pubertal male rats without changes in ethanol metabolism. In male rats, a higher dose of ethanol was required to abolish LTD at 24-h delay. In pubertal female rats, tamoxifen, an antagonist of estrogen receptors, blocked the impairing effects of endogenous and exogenous E2 on LTD, suggesting estrogen interacts with ethanol through changes in gene expression. In addition, tamoxifen prevented LTD abolition at 24 h but not at 48-h delay. In conclusion, estrogen may explain the increased vulnerability to ethanol-induced plasticity impairment seen in females compared with males. This increased vulnerability of female rats is likely due to changes in the GluN2B subunit that represent a common target between ethanol and estrogen.

Training emotion regulation processes in alcohol-abstinent individuals: A pilot study

The study aimed to assess whether abstinent individuals with alcohol use disorders (AUD) would benefit from enhanced emotional regulation (ER) strategies using the affect regulation training (ART) program based on weekly sessions comprising psycho-education, muscle and respiratory relaxation, awareness, acceptance and tolerance, compassionate personal support, emotion analysis and modification. Seventy-two participants with AUD benefited from ART and were compared on their ER ability, mindfulness, and their experience of abstinence to 40 participants not receiving the program, before it, at the end, and 6 months after. Improvements in ER were observed, particularly in positive centration, action centration or self-blame and in mindfulness abilities after the program and six months later. In addition, by comparing participants who received the program with a short (<18 months) or long (>18 months) abstinence duration, the results showed a greater decrease in the use of non-adaptive strategies, a greater increase in adaptive strategies and mindfulness abilities in short-term abstinent individuals. These results demonstrate improvement in ER skills after training in people who were abstinent from alcohol. ART is effective for consolidating abstinence and should be used especially at the beginning of withdrawal to promote the rapid implementation of new ER strategies.

Role of heat shock transcription factor 2 in the NMDA-dependent neuroplasticity induced by chronic ethanol intake in mouse hippocampus

Ethanol consumption impairs learning and memory through disturbances of NMDA-type glutamate receptor-dependent synaptic plasticity (long-term depression [LTD] and long-term potentiation [LTP]) in the hippocampus. Recently, we demonstrated that two ethanol binge-like episodes in young adult rats selectively blocked NMDA-LTD in hippocampal slices, increased NMDA receptor sensitivity to a GluN2B subunit antagonist, and induced cognitive deficits. Here, using knockout adult mice, we show that a stress-responsive transcription factor of the heat shock factor family, HSF2, which is involved in the perturbation of brain development induced by ethanol, participates in these processes. In the absence of ethanol, hsf2^-/- mice show a selective loss of LTD in the hippocampus, which is associated with an increased sensitivity of NMDA-field excitatory postsynaptic potentials (fEPSPs) to a GluN2B antagonist, compared with wild-type (WT) mice. These results suggest that HSF2 is required for proper glutamatergic synaptic transmission and LTD plasticity. After 1 month of chronic ethanol consumption in a two-bottle choice paradigm, WT mice showed an increase in hippocampal synaptic transmission, an enhanced sensitivity to GluN2B antagonist, and a blockade of LTD. In contrast, such modulation of synaptic transmission and plasticity were absent in hsf2^-/- mice. We conclude that HSF2 is an important mediator of both glutamatergic neurotransmission and synaptic plasticity in basal conditions and also mediates ethanol-induced neuroadaptations of the hippocampus network after chronic ethanol intake.

Is R(+)-Baclofen the best option for the future of Baclofen in alcohol dependence pharmacotherapy? Insights from the preclinical side

For several decades, studies conducted to evaluate the efficacy of RS(±)-Baclofen in the treatment of alcohol dependence yielded contrasting results. Human and animal studies recently questioned the use of the racemic drug in patients since a potential important role of the different enantiomers has been revealed with an efficacy thought to reside with the active R(+)-enantiomer. Here we conducted experiments in the postdependent rat model of alcohol dependence to compare the efficacy of R(+)-Baclofen or S(-)-Baclofen to that of RS(±)-Baclofen on ethanol intake, seeking, and relapse. R(+)-Baclofen was more effective than RS(±)-Baclofen in reducing ethanol intake and seeking during acute withdrawal and during relapse after abstinence. We also used an original population approach in order to identify drug responders. We found a significant proportion of responders to S(-)-Baclofen and RS(±)-Baclofen, displaying an increase in ethanol intake, and this increasing effect on alcohol intake was not seen in the R(+)-Baclofen group. At an intermediate dose of R(+)-Baclofen, devoid of any motor side effects, we identified a very large proportion of responders (75%) with a large decrease in ethanol intake (90% decrease). Finally, the response to RS(±)-Baclofen on ethanol intake was correlated to plasma level of Baclofen. R(+)-Baclofen and RS(±)-Baclofen were effective in reducing sucrose intake. Our study has important clinical implication since it suggests that the wide variability in the therapeutic responses of patients to RS(±)-Baclofen may come from the sensitivity to the R(+)-Baclofen but also to the one of the S(-)-Baclofen that can promote an increase in ethanol intake.

The Early Impact of the COVID-19 Lockdown on Stress and Addictive Behaviors in an Alcohol-Consuming Student Population in France

Background: This study evaluated factors linked with perceived stress related to the COVID-19 pandemic and lockdown and addictive behaviors prior to and during lockdown in a sample of students who indicated engaging in alcohol consumption behaviors before lockdown. Methods: Cross-sectional study. French students from four universities participated in this study, and 2,760 students reported alcohol use. During the first week of lockdown, students reported their perceived levels of stress regarding COVID-19. Substance use and addictive behaviors were reported before and during lockdown, and media exposure, demographical, living conditions, and environmental stressors were reported during lockdown. Results: Women reported greater levels of stress (95% CI: 1.18 to 1.93, p < 0.001). Highly-stressed students also report less social support (95% CI: -1.04 to -0.39, p < 0.001) and were more likely to worry about the lockdown (95% CI: 0.27 to -0.65, p < 0.001). Alcohol-related problemswere more prevalent among the most stressed students (95% CI: 0.02 to 0.09, p = 0.004) as well as eating problems (95% CI: 0.04 to 0.36, p = 0.016) and problematic internet use (95% CI, 0.06 to 0.14, p < 0.001). Students reporting the highest levels of stress also indicated more compulsive eating during the previous seven days (95% CI, 0.21 to 1.19, p = 0.005). Conclusions: The level of stress was strongly related to four categories of variables: (i) intrinsic characteristics, (ii) addictive behaviors before lockdown, (iii) lockdown-specific conditions, and (iv) addictive behaviors during the lockdown. Several variables linked to COVID-19 were not directly linked with perceived stress, while perceived stress was found to correlate with daily life organization-related uncertainty and anticipated consequences of lockdown. Importantly, social support seems to be a protective factor on high level of stress.

Patch-Clamp Recording of Low Frequency Stimulation-induced Long-Term Synaptic Depression in Rat Hippocampus Slices During Early and Late Neurodevelopment

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.

COVID-19 pandemic lockdown and problematic eating behaviors in a student population

BACKGROUND AND AIMS

Since mid-March 2020, over 3 billion people have been confined as a result of the COVID-19 pandemic. Problematic eating behaviors are likely to be impacted by the pandemic through multiple pathways. This study examined the relationships between stress related to lockdown measures and binge eating and dietary restriction in a population of French students during the first week of confinement.

METHODS

A sample of undergraduate students (N = 5,738) completed an online questionnaire 7 days after lockdown measures were introduced. The survey comprised variables related to lockdown measures and the COVID-19-pandemic, mood, stress, body image, binge eating and dietary restriction during the past 7 days, as well as intent to binge eat and restrict in the following 15 days.

RESULTS

Stress related to the lockdown was associated with greater likelihood of binge eating and dietary restriction over the past week and intentions to binge eat and restrict over the next 15 days. Greater exposure to COVID-19-related media was associated with increased eating restriction over the past week. Binge eating and restriction (past and intentions) were associated with established risk factors, including female gender, low impulse regulation, high body dissatisfaction, and having a concurrent probable eating disorder.

DISCUSSION AND CONCLUSION

The higher the stress related to the first week of confinement, the higher the risk of problematic eating behaviors among students, particularly those characterized by eating-related concerns. Screening for risk factors and providing targeted interventions might help decrease problematic eating behaviors among those who are most vulnerable.

Memory and plasticity impairment after binge drinking in adolescent rat hippocampus: GluN2A/GluN2B NMDA receptor subunits imbalance through HDAC2

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.

Ethanol (EtOH)-Related Behaviors in α-Synuclein Mutant Mice and Association of SNCA SNPs with Anxiety in EtOH-Dependent Patients

BACKGROUND

Data have shown a role of α-synuclein in anxiety and also in addiction, particularly in alcohol use disorders (AUD). Since the comorbidity between AUD and anxiety is very high and because anxiety is an important factor in ethanol (EtOH) relapse, the aim of the present study was to investigate the role of α-synuclein in moderating EtOH intake, the anxiolytic effects of EtOH, and EtOH withdrawal-induced anxiety and convulsions in mice. The study aimed to determine whether SNCA variants moderated anxiety in EtOH-dependent patients.

METHODS

We analyzed the moderator effect of 3 SNCA Tag-single nucleotide polymorphisms (Tag-SNPs) rs356200, rs356219, and rs2119787 on the anxiety symptoms in 128 EtOH-dependent patients. We used the C57BL/6JOlaHsd Snca mutant mice to assess EtOH intake; sensitivity to the anxiolytic effects of EtOH in a test battery comprising the open field, the light-dark box, and the elevated plus maze; and both anxiety and convulsions induced by EtOH withdrawal.

RESULTS

Our results demonstrated a reduction in both EtOH intake and preference and also a lack of sensitivity to the anxiolytic effects of EtOH in α-synuclein mutant mice. Results on anxiety-like behavior were mixed, but mutant mice displayed increased anxiety when exposed to a low anxiogenic environment. Mutant mice also displayed an increase in handling-induced convulsion scores during withdrawal after EtOH inhalation, but did not differ in terms of EtOH withdrawal-induced anxiety. In humans, we found a significant association of the rs356219 SNP with a high level of anxiety (Beck Anxiety Inventory score >15) and the rs356200 SNP with a positive familial history of AUD.

CONCLUSIONS

Our translational study highlights a significant role of α-synuclein in components of AUD.

Effect of N-acetylcysteine on motivation, seeking and relapse to ethanol self-administration

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_c^- 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.

Signaling lymphocytic activation molecules Slam and cancers: friends or foes?

Signaling Lymphocytic Activation Molecules (SLAM) family receptors are initially described in immune cells. These receptors recruit both activating and inhibitory SH2 domain containing proteins through their Immunoreceptor Tyrosine based Switch Motifs (ITSMs). Accumulating evidence suggest that the members of this family are intimately involved in different physiological and pathophysiological events such as regulation of immune responses and entry pathways of certain viruses. Recently, other functions of SLAM, principally in the pathophysiology of neoplastic transformations have also been deciphered. These new findings may prompt SLAM to be considered as new tumor markers, diagnostic tools or potential therapeutic targets for controlling the tumor progression. In this review, we summarize the major observations describing the implications and features of SLAM in oncology and discuss the therapeutic potential attributed to these molecules.

Hepatocyte SLAMF3 reduced specifically the multidrugs resistance protein MRP-1 and increases HCC cells sensitization to anti-cancer drugs

Multidrug resistance MDR proteins (MRPs) are members of the C family of a group of proteins named ATP binding cassette (ABC) transporters. MRPs can transport drugs including anticancer drugs, nucleoside analogs, antimetabolites and tyrosine kinase inhibitors. Drugs used in HCC therapy, such as tyrosine kinase inhibitor sorafenib, are substrates of uptake and/or efflux transporters. Variable expression of MRPs at the plasma membrane of tumor cells may contribute to drug resistance and subsequent clinical response. Recently, we reported that the hepatocyte SLAMF3 expression (Signaling Lymphocytic Activation Molecule Family member 3) was reduced in tumor cells from hepatocellular carcinoma (HCC) compared to its high expression in adjacent tissues. In the present study, we make a strong correlation between induced SLAMF3 overexpression and the specific loss of MRP-1 expression and its functionalities as a drugs resistance transporter. No changes were observed on expression of ABCG2 and MDR. More importantly, we highlight a strong inverse correlation between MRP-1 and SLAMF3 expression in patients with HCC. We propose that the SLAMF3 overexpression in cancerous cells could represent a potential therapeutic strategy to improve the drugs sensibility of resistant cells and thus control the therapeutic failure in HCC patients.

Increase of KCC2 in hippocampal synaptic plasticity disturbances after perinatal ethanol exposure

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 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.

Binge Eating, But Not Other Disordered Eating Symptoms, Is a Significant Contributor of Binge Drinking Severity: Findings from a Cross-Sectional Study among French Students

Many studies have suggested the co-occurrence of eating disorders and alcohol use disorders but in which extent binge eating (BE) and other disordered eating symptoms (DES) are associated with the severity of binge drinking (BD) remains unknown. We conducted a online cross-sectional study among 1,872 French students. Participants were asked their age, gender, tobacco and cannabis use status. They completed the Alcohol Use Questionnaire (AUQ), Eating Disorder Examination Questionnaire (EDE-Q), and UPPS impulsive behavior questionnaire. BD score was calculated using the AUQ. Three items of the EDE-Q were used to construct a BE score. The predictors of the BD score were determined using a linear regression model. Our results showed that the BE score was correlated with the BD score (β₀ = 0.051 ± 0.022; p = 0.019), but no other DES was associated with BD, including purging behaviors. The severity of BD was also correlated with younger age, male gender, tobacco and cannabis use, and with the 'positive urgency,' 'premeditation,' and 'sensation seeking' UPPS subscores (R² of the model: 25%). Within DES, BE appeared as an independent determinant of the BD severity. This is in line with the recent hypothesis that BE is not a subtype of DES, but more a general vulnerability factor of emotional dysregulation, which could be shared by different behavioral and addictive disorders.

[Epigenetic mechanisms and alcohol use disorders: a potential therapeutic target]

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.

Resistance to ethanol sensitization is associated with a loss of synaptic plasticity in the hippocampus

Behavioral sensitization to repeated ethanol (EtOH) exposure induces an increase in locomotor activity in mice. However, not all animals express such sensitization. Although the literature indicated that the hippocampus may play a role in EtOH sensitization, it is not known whether behavioral sensitization to EtOH is associated with preferential changes in bidirectional synaptic plasticity, i.e., LTP and LTD, two markers of learning capabilities that have also been shown to be involved in addictive behavior. In the present study, we examined whether the vulnerability to develop and express behavioral sensitization to EtOH is associated with altered bidirectional synaptic plasticity in the CA1 area of the dorsal hippocampus. For this purpose, we analyzed both LTP and LTD in resistant and sensitized mice during the expression phase, i.e., 7 days after 10 days of repeated EtOH i.p. administration. We found that resistant mice showed a lack of LTD without changes in LTP. The lack of LTD was associated with an increase in GluN2A protein level and was not due to an altered level of neuronal activity, since no difference was observed between the number of c-FOS positive neurons in sensitized and resistant mice. Given that both types of synaptic plasticity signals may have distinct roles in specific learning and behaviors, our results suggest that resistant mice could exhibit different phenotypes in terms of learning/memory and addictive behaviors compared to sensitized ones. Synapse 71:e21899, 2017. © 2016 Wiley Periodicals, Inc.

Impact cérébral du binge drinking et vulnérabilité à l’alcoolodépendance

Les conséquences à court terme et à long terme du binge drinking sur le cerveau et son fonctionnement commencent à être bien appréhendés. Sa pratique est banalisée et donc courante chez les jeunes. Nous avons initié une série d’études dans le cadre du projet européen AlcoBinge visant à mesurer les conséquences cérébrales morphologiques et fonctionnelles dans une population d’étudiants. Nous avons aussi utilisé la modélisation animale pour rechercher les conséquences à court terme sur les capacités cognitives et les phénomènes de plasticité synaptique après seulement quelques épisodes de binge drinking. La vulnérabilité à long terme à l’alcoolodépendance a été étudiée dans ces mêmes modèles animaux. Nos résultats démontrent que le binge drinking entraîne à la fois des atteintes de la substance blanche et de la substance grise qui peuvent être corrélées à des déficits d’apprentissage et de mémorisation. Chez l’animal nos résultats montrent que deux épisodes de binge drinking suffisent pour induire des perturbations importantes de certaines formes de plasticité synaptique hippocampique associées à des déficits d’apprentissage et de mémorisation. Ces atteintes semblent particulièrement impliquer les récepteurs NMDA du glutamate car les effets de l’alcool sont mimés par la kétamine et bloqués par la D-serine. De manière inquiétante, quelques épisodes de binge drinking à l’adolescence suffisent pour induire une forte motivation pour la consommation d’alcool à l’âge adulte associée à une plus grande anxiété et une moindre réactivité du noyau accumbens à l’alcool. Au total l’ensemble de ces résultats cliniques et précliniques suggèrent que le binge drinking est particulièrement toxique au niveau cérébral et augmente le risque d’alcoolodépendances à l’âge adulte.

Rôle de la sensibilisation aux effets stimulants de l’alcool dans l’addiction et implication de la plasticité synaptique hippocampique

Parmi les théories de l’addiction, celle de la sensibilisation comportementale tient une place importante avec l’augmentation de la motivation à consommer la drogue au fil des expositions répétées (sensibilisation de la valeur incitatrice de la drogue encore appelée sensibilisation motivationnelle). Cependant, il existe très peu de preuves du rôle de cette sensibilisation dans le comportement addictif. La sensibilisation pourrait jouer un rôle majeur non seulement dans l’escalade de la consommation mais aussi dans le phénomène de rechute et le craving, une composante majeure de l’addiction. Nous avons déjà démontré une corrélation inverse entre comportement de type anxieux et vulnérabilité à développer la sensibilisation. Toujours dans une approche heuristique du phénomène, nous avons réalisé des expériences chez la souris pour déterminer le rôle de ce phénomène de sensibilisation dans la motivation à consommer de l’alcool. Nous avons aussi voulu savoir si des modifications de plasticité synaptique hippocampique pouvaient être associées à vulnérabilité au phénomène de sensibilisation. Nos résultats démontrent une vulnérabilité individuelle face au phénomène de sensibilisation aux effets stimulants moteurs de l’alcool : des souris présentant une forte sensibilisation alors que d’autres sont complètement résistantes. Les souris sensibilisées sont celles qui présentent la plus forte consommation d’alcool dans une procédure d’auto-administration opérante d’alcool et surtout celles qui présentent la plus forte motivation à consommer de l’alcool dans un paradigme de ratio progressif où le prix à payer pour obtenir de l’alcool augmente lors d’une même session. Enfin nos résultats d’électrophysiologie démontrent des atteintes spécifiques de la dépression synaptique à long terme chez les souris résistantes et ouvrent donc des perspectives intéressantes en termes de bases neurobiologiques. L’ensemble de ces résultats a une incidence majeure dans le champ de l’addiction à l’alcool car c’est la première fois que la relation entre vulnérabilité à la sensibilisation et motivation à consommer de l’alcool est établie.

Comparison of the deleterious effects of binge drinking-like alcohol exposure in adolescent and adult mice

A major cause of alcohol toxicity is the production of reactive oxygen species generated during ethanol metabolism. The aim of this study was to compare the effect of binge drinking-like alcohol exposure on a panel of genes implicated in oxidative mechanisms in adolescent and adult mice. In adolescent animals, alcohol decreased the expression of genes involved in the repair and protection of oxidative DNA damage such as atr, gpx7, or nudt15 and increased the expression of proapoptotic genes such as casp3. In contrast, in the adult brain, genes activated by alcohol were mainly associated with protective mechanisms that prevent cells from oxidative damage. Whatever the age, iterative binge-like episodes provoked the same deleterious effects as those observed after a single binge episode. In adolescent mice, multiple binge ethanol exposure substantially reduced neurogenesis in the dentate gyrus and impaired short-term memory in the novel object and passive avoidance tests. Taken together, our results indicate that alcohol causes deleterious effects in the adolescent brain which are distinct from those observed in adults. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity. The effects of alcohol exposure were investigated on genes involved in oxidative mechanisms. In adolescent animals, alcohol decreased the expression of genes involved in DNA repair, a potential cause of the observed decrease of neurogenesis. In contrast, in the adult brain, alcohol increased the expression of genes associated with antioxidant mechanisms. Apoptosis was increase in all groups and converged with other biochemical alterations to enhance short-term memory impairment in the adolescent brain. These data contribute to explain the greater sensitivity of the adolescent brain to alcohol toxicity.

Aberrant NMDA-dependent LTD after perinatal ethanol exposure in young adult rat hippocampus

Irreversible cognitive deficits induced by ethanol exposure during fetal life have been ascribed to a lower NMDA-dependent synaptic long-term potentiation (LTP) in the hippocampus. Whether NMDA-dependent long-term depression (LTD) may also play a critical role in those deficits remains unknown. Here, we show that in vitro LTD induced with paired-pulse low frequency stimulation is enhanced in CA1 hippocampus field of young adult rats exposed to ethanol during brain development. Furthermore, single pulse low frequency stimulation, ineffective at this age (LFS600), induced LTD after ethanol exposure accompanied with a stronger response than controls during LFS600, thus revealing an aberrant form of activity-dependent plasticity at this age. Blocking NMDA receptor or GluN2B containing NMDA receptor prevented both the stronger response during LFS600 and LTD whereas Zinc, an antagonist of GluN2A containing NMDA receptor, was ineffective on both responses. In addition, LFS600-induced LTD was revealed in controls only with a reduced-Mg(2+) medium. In whole dissected hippocampus CA1 field, perinatal ethanol exposure increased GluN2B subunit expression in the synaptic compartment whereas GluN2A was unaltered. Using pharmacological tools, we suggest that LFS600 LTD was of synaptic origin. Altogether, we describe a new mechanism by which ethanol exposure during fetal life induces a long-term alteration of synaptic plasticity involving NMDA receptors, leading to an aberrant LTD. We suggest this effect of ethanol may reflect a delayed maturation of the synapse and that aberrant LTD may also participates to long-lasting cognitive deficits in fetal alcohol spectrum disorder.