Fluoxetine, desipramine, and the dual antidepressant milnacipran reduce alcohol self-administration and/or relapse in dependent rats

Ethanol deprivation and central 5-HT deficiency differentially affect the mRNA editing of the 5-HT2C receptor in the mouse brain

BACKGROUND

Serotonin (5-HT) 5-HT2C receptor mRNA editing (at five sites, A-E), implicated in neuropsychiatric disorders, including clinical depression, remains unexplored during alcohol abstinence-often accompanied by depressive symptoms.

METHODS

We used deep sequencing to investigate 5-HT2C receptor editing in mice during early ethanol deprivation following prolonged alcohol exposure and mice lacking tryptophan hydroxylase (TPH)2, a key enzyme in central 5-HT production. We also examined Tph2 expression in ethanol-deprived animals using quantitative real-time PCR (qPCR).

RESULTS

Cessation from chronic 10% ethanol exposure in a two-bottle choice paradigm enhanced immobility time and decreased latency in the forced swim test (FST), indicating a depression-like phenotype. In the hippocampus, ethanol-deprived "high ethanol-drinking" mice displayed reduced Tph2 expression, elevated 5-HT2C receptor editing efficiency, and decreased frequency of the D mRNA variant, encoding the less-edited INV protein isoform. Tph2-/- mice showed attenuated receptor editing in the hippocampus and elevated frequency of non-edited None and D variants. In the prefrontal cortex, Tph2 deficiency increased receptor mRNA editing at site D and reduced the frequency of AB transcript, predicting a reduction in the corresponding partially edited VNI isoform.

CONCLUSIONS

Our findings reveal differential effects of 5-HT depletion and ethanol cessation on 5-HT2C receptor editing. Central 5-HT depletion attenuated editing in the prefrontal cortex and the hippocampus, whereas ethanol deprivation, coinciding with reduced Tph2 expression in the hippocampus, enhanced receptor editing efficiency specifically in this brain region. This study highlights the interplay between 5-HT synthesis, ethanol cessation, and 5-HT2C receptor editing, providing potential mechanism underlying increased ethanol consumption and deprivation.

Transcranial direct current stimulation (tDCS) reduces motivation to drink ethanol and reacquisition of ethanol self-administration in female mice

Transcranial direct current stimulation (tDCS) is an emerging noninvasive brain neuromodulation technique aimed at relieving symptoms associated with psychiatric disorders, including addiction. The goal of the present study was to better identify which phase of alcohol-related behavior (hedonic effect, behavioral sensitization, self-administration, or motivation to obtain the drug) might be modulated by repeated anodal tDCS over the frontal cortex (0.2 mA, 20 min, twice a day for 5 consecutive days), using female mice as a model. Our data showed that tDCS did not modulate the hedonic effects of ethanol as assessed by a conditioned place preference test (CPP) or the expression of ethanol-induced behavioral sensitization. Interestingly, tDCS robustly reduced reacquisition of ethanol consumption (50% decrease) following extinction of self-administration in an operant paradigm. Furthermore, tDCS significantly decreased motivation to drink ethanol on a progressive ratio schedule (30% decrease). Taken together, our results show a dissociation between the effects of tDCS on “liking” (hedonic aspect; no effect in the CPP) and “wanting” (motivation; decreased consumption on a progressive ratio schedule). Our tDCS procedure in rodents will allow us to better understand its mechanisms of action in order to accelerate its use as a complementary and innovative tool to help alcohol-dependent patients maintain abstinence or reduce ethanol intake.

The interaction between Environmental Enrichment and fluoxetine in inhibiting sucrose-seeking renewal in mice depend on social living condition

RATIONALE

Several single or combined therapeutic approaches have been developed to treat addiction, however with partial efficacy in preventing relapse. Recently, the living environment has been suggested as a critical intervening factor determining the treatment outcomes. Despite accumulating evidence confirming a role of living conditions in the vulnerability to addictive behaviours, their impact on single or integrative therapeutic strategies preventing relapse is yet to be identified.

OBJECTIVES

Here, we explore the possible interaction between brief Environmental Enrichment (EE) exposure and acute fluoxetine administration in inhibiting sucrose-seeking behaviours, and whether this effect could be affected by living environment.

METHODS

Social and isolated adult male C57BL/6 mice were trained to sucrose self-administration associated to a specific conditioning context (CxA), followed by a 7-day extinction in a different context (CxB). Afterwards, mice were exposed for 22 h to EE and then injected with fluoxetine (10 mg/kg, i.p.) 1 h before a CxA-induced sucrose-seeking test.

RESULTS

Brief EE exposure and acute fluoxetine administration alone inhibited context-induced sucrose-seeking in both housing conditions; however, they exhibited additive properties only in social condition.

CONCLUSIONS

Our data show that social environment may influence the EE/fluoxetine interaction in inhibiting relapse to sucrose. These findings suggest that setting up proper living conditions to boost the efficacy of therapeutic approaches may represent a fundamental strategy to treat addiction disorders.

Sudden cessation of fluoxetine before alcohol drinking reinstatement alters microglial morphology and TLR4/inflammatory neuroadaptation in the rat brain

Preclinical studies on the effects of abrupt cessation of selective serotonin reuptake inhibitors (SSRIs), a medication often prescribed in alcohol use disorder (AUD) patients with depression, results in alcohol consumption escalation after resuming drinking. However, a potential neuroinflammatory component on this escalation remains unexplored despite the immunomodulatory role of serotonin. Here, we utilized a rat model of 14-daily administration of the SSRI fluoxetine (10 mg/kg/day) along alcohol self-administration deprivation to study the effects of fluoxetine cessation on neuroinflammation after resuming alcohol drinking. Microglial morphology and inflammatory gene expression were analyzed in prelimbic cortex, striatum, basolateral amygdala and dorsal hippocampus. Results indicated that alcohol drinking reinstatement increased microglial IBA1 immunoreactivity and altered morphometric features of activated microglia (fractal dimension, lacunarity, density, roughness, and cell area, perimeter and circularity). Despite alcohol reinstatement, fluoxetine cessation modified microglial morphology in a brain region-specific manner, resulting in hyper-ramified (spatial complexity of branching), reactive (lower heterogeneity and circularity)-like microglia. We also found that microglial cell area correlated with changes in mRNA expression of chemokines (Cx3cl1/fractalkine, Cxcl12/SDF1α, Ccl2/MCP1), cytokines (IL1β, IL6, IL10) and the innate immune toll-like receptor 4 (TLR4) in dorsal hippocampus. Specifically, TLR4 correlated with microglial spatial complexity assessed by fractal dimension in striatum, suggesting a role in process branching. These findings suggest that alcohol drinking reinstatement after fluoxetine treatment cessation disturbs microglial morphology and reactive phenotype associated with a TLR4/inflammatory response to alcohol in a brain region-specific manner, facts that might contribute to alcohol-induced damage through the promotion of escalation of alcohol drinking behavior.

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.

Cessation of fluoxetine treatment increases alcohol seeking during relapse and dysregulates endocannabinoid and glutamatergic signaling in the central amygdala

Administration of selective serotonin reuptake inhibitors (SSRIs), typically used as antidepressants, induces long-lasting behavioral changes associated with alcohol use disorder (AUD). However, the contribution of SSRI (fluoxetine)-induced alterations in neurobiological processes underlying alcohol relapse such as endocannabinoid and glutamate signaling in the central amygdala (CeA) remains largely unknown. We utilized an integrative approach to study the effects of repeated fluoxetine administration during abstinence on ethanol drinking. Gene expression and biochemical and electrophysiological studies explored the hypothesis that dysregulation in glutamatergic and endocannabinoid mechanisms in the CeA underlie the susceptibility to alcohol relapse. Cessation of daily treatment with fluoxetine (10 mg/kg) during abstinence resulted in a marked increase in ethanol seeking during re-exposure periods. The increase in ethanol self-administration was associated with (a) reductions in levels of the endocannabinoids N-arachidonoylethanolomine and 2-arachidonoylglycerol in the CeA, (b) increased amygdalar gene expression of cannabinoid type-1 receptor (CB1), N-acyl phosphatidylethanolamine phospholipase D (Nape-pld), fatty acid amid hydrolase (Faah), (c) decreased amygdalar gene expression of ionotropic AMPA (GluA2 and GluA4) and metabotropic (mGlu3) glutamate receptors, and (d) increased glutamatergic receptor function. Overall, our data suggest that the administration of the antidepressant fluoxetine during abstinence dysregulates endocannabinoid signaling and glutamatergic receptor function in the amygdala, facts that likely facilitate alcohol drinking behavior during relapse.

Kamikihito Enhances Cognitive Functions and Reward-Related Behaviors of Aged C57BL/6J Mice in an Automated Behavioral Assay System

The cognitive and psychological domains of frailty in the elderly have drawn increasing attention given the aging of society. However, therapeutics to treat minor deficits in cognition and mental state in the elderly remain an unmet need. Kamikihito (KKT), a traditional Japanese Kampo medicine indicated for neuroses, anxiety, and insomnia, is effective for treating cognitive dysfunction and depressive-like behaviors in animal models, suggesting that it may have therapeutic potential for treating cognitive and/or mental frailty. In this study, we first validated the known anxiolytic effects of KKT in a conventional maze test. We then introduced an automated behavioral assay system, IntelliCage, to evaluate the therapeutic potential of KKT for age-related and diverse central functions by performing sequential behavioral tasks in young and aged mice to assess basal activities, cognitive functions, perseveration, and hedonic-related behaviors. Although young mice treated with KKT did not exhibit changes in diurnal variation, KKT-administered aged mice exhibited an accelerated decline in voluntary activity during the early part of the light period, implying that KKT may promote sleep onset in aged mice. Neither place learning acquisition for gaining rewards nor subsequent behavioral flexibility performance was altered by KKT in the young group, whereas the aged KKT group exhibited significantly enhanced performance in both phases of learning relative to age-matched controls. Conversely, perseverative nose-pokes (NPs) to gain rewards observed during place learning, indicative of compulsivity, were attenuated by KKT in both age groups. Regarding hedonic processing, aged mice exhibited a decreased preference for sweet solutions compared to young mice, which was effectively reversed by KKT treatment. Furthermore, KKT elevated high-effort choices for high-value reward in an effort-based decision-making paradigm in both age groups, implying augmentation of motivational behaviors by KKT. Collectively, KKT exerted various beneficial effects in cognitive and emotional domains, several of which were more evident in aged mice than in young mice, suggesting the potential of KKT for treating cognitive and mental frailty.

microRNA-155 Modulates Hepatic Stellate Cell Proliferation, Apoptosis, and Cell Cycle Progression in Rats With Alcoholic Hepatitis via the MAPK Signaling Pathway Through Targeting SOCS1

The aim of this study was to investigate the regulatory function of the non-coding microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS1) in alcoholic hepatitis (AH) and its potential mechanism associated with the mitogen-activated protein kinase (MAPK) signaling pathway. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), total bilirubin (TBIL), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured in a rat model of AH. The biological prediction website microRNA.org and dual-luciferase reporter gene assay were used to identify whether SOCS1 was a direct target of miR-155, and the effects of miR-155 and SOCS1 on the viability, cycle progression, and apoptosis of hepatic stellate cells were assessed using RT-qPCR, Western blot assay, MTT assay, Annexin V/PI double staining, and PI single staining. The levels of ALT, AST, MDA, and TBIL and the liver cell morphology were all prominently changed in AH model rats. miR-155 suppressed SOCS1 by specifically binding to SOCS1-3'-UTR to activate the MAPK signaling pathway. SOCS1 had low expression while miR-155 was highly expressed in AH rats. miR-155 promoted hepatic stellate cell viability and cycle progression and reduced cell apoptosis by silencing SOCS1. Together, we find that silenced miR-155 could upregulate SOCS1 and inactivate the MAPK signaling pathway, thereby inhibiting the proliferation of alcoholic hepatic stellate cells and promoting cell apoptosis.

Evidence for incentive salience sensitization as a pathway to alcohol use disorder

The incentive salience sensitization (ISS) theory of addiction holds that addictive behavior stems from the ability of drugs to progressively sensitize the brain circuitry that mediates attribution of incentive salience (IS) to reward-predictive cues and its behavioral manifestations. In this article, we establish the plausibility of ISS as an etiological pathway to alcohol use disorder (AUD). We provide a comprehensive and critical review of evidence for: (1) the ability of alcohol to sensitize the brain circuitry of IS attribution and expression; and (2) attribution of IS to alcohol-predictive cues and its sensitization in humans and non-human animals. We point out gaps in the literature and how these might be addressed. We also highlight how individuals with different alcohol subjective response phenotypes may differ in susceptibility to ISS as a pathway to AUD. Finally, we discuss important implications of this neuropsychological mechanism in AUD for psychological and pharmacological interventions attempting to attenuate alcohol craving and cue reactivity.

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.

Advancing Pharmacotherapy Development from Preclinical Animal Studies

Animal models provide rapid, inexpensive assessments of an investigational drug's therapeutic potential. Ideally, they support the plausibility of therapeutic efficacy and provide a rationale for further investigation. Here, I discuss how the absence of clear effective-ineffective categories for alcohol use disorder (AUD) medications and biases in the clinical and preclinical literature affect the development of predictive preclinical alcohol dependence (AD) models. Invoking the analogical argument concept from the philosophy of science field, I discuss how models of excessive alcohol drinking support the plausibility of clinical pharmacotherapy effects. Even though these models are not likely be completely discriminative, they are sensitive to clinically effective medications and have revealed dozens of novel medication targets. In that context, I discuss recent preclinical work on GLP-1 receptor agonists, phosphodiesterase inhibitors, glucocorticoid receptor antagonists, nociception agonists and antagonists, and CRF1 antagonists. Clinically approved medications are available for each of these drug classes. I conclude by advocating a translational approach in which drugs are evaluated highly congruent preclinical models and human laboratory studies. Once translation is established, I suggest the burden is to develop hypothesis-based therapeutic interventions maximizing the impact of the confirmed pharmacotherapeutic effects in the context of additional variables falling outside the model.

State of Training, Clinical Services, and Research on Dual Disorders Across France, India, Israel, and Spain

OBJECTIVE

This article overviews training, clinical services, and research on dual disorders across four countries: France, India, Israel, and Spain.

METHODS

The current dual disorders systems in each of the four countries were reviewed, with a focus on strengths and limitations of each.

RESULTS

In France, psychiatric care occurs within the public health care system and involves little training of medical graduates for managing dual disorders. Special courses and forums for specialists have recently started to meet the growing interest of physicians in learning how to manage dual disorders. The Indian health care system grapples with a large treatment gap for mental disorders, and while some treatment services for dual disorders exist, specific research and training efforts on dual disorders are just beginning. Israel has both public- and private sector services for patients with dual disorders, with specialized inpatient and emergency care for the acutely ill as well as day care and therapeutic communities for long-term management. Interest by researchers is growing, but training and education efforts in dual disorders are, however, minimal. Similar to the other countries, addiction and psychiatry disciplines are governed by separate divisions within the National Health System in Spain. There are some dual disorders services available, but they are limited in scope. While medical professionals clearly recognize the importance of dual disorders, there is no such recognition by the national and regional governing bodies.

CONCLUSIONS

The common thread in various aspects of dual disorder management in each of these four countries is that there is a lower-than-desirable level of attention to dual disorders in terms of care, policy, research, and training. There are growing opportunities for training and continuing education in dual disorders management. We suggest that nations could learn from each other's experiences on how to address the issue of dual disorders.

Effects of iloperidone, combined with desipramine, on alcohol drinking in the Syrian golden hamster

Alcohol use disorder in patients with schizophrenia dramatically worsens their clinical course, and few treatment options are available. Clozapine appears to reduce alcohol use in these patients, but its toxicity limits its use. To create a safer clozapine-like drug, we tested whether the antipsychotic iloperidone, a drug that combines a weak dopamine D2 receptor blockade and a potent norepinephrine alpha-2 receptor blockade would reduce alcohol drinking, and whether its effect on alcohol drinking could be increased if combined with an agent to facilitate norepinephrine activity. Syrian golden hamsters (useful animal model for screening drugs that reduce alcohol drinking in patients with schizophrenia) were given free access to water and alcohol (15% v/v) until stable drinking was established. Animals (n = 6-7/group), matched according to alcohol intake, were treated daily with each drug (iloperidone; clozapine; haloperidol; desipramine [norepinephrine reuptake inhibitor]; with idazoxan [norepinephrine alpha-2 receptor antagonist]) or with a two-drug (iloperidone + desipramine; iloperidone + idazoxan) combination for 14 days. Moderate doses of iloperidone (1-5 mg/kg) significantly reduced alcohol drinking (p < 0.05) in the hamster, whereas higher doses (10-20 mg/kg) did not. In addition, 5 mg/kg of iloperidone reduced alcohol drinking to the same extent as clozapine (8 mg/kg), whereas haloperidol (0.2 mg/kg) did not. Moreover, iloperidone's effects were enhanced via the addition of desipramine (3 mg/kg), but not idazoxan (1.5/3 mg/kg). In this animal model, iloperidone decreases alcohol drinking as effectively as clozapine, and desipramine appears to amplify this effect. The data suggest that iloperidone, alone or in combination with desipramine, should be tested in patients with schizophrenia and alcohol use disorder.

Serotonin's Complex Role in Alcoholism: Implications for Treatment and Future Research

Current pharmacological treatments for alcohol dependence have focused on reducing alcohol consumption, but to date there are few treatments that also address the negative affective symptoms during acute and protracted alcohol withdrawal which are often exacerbated in people with comorbid anxiety and depression. Selective serotonin reuptake inhibitors (SSRIs) are sometimes prescribed to ameliorate these symptoms but can exacerbate anxiety and cravings in a select group of patients. In this critical review, we discuss recent literature describing an association between alcohol dependence, the SERT linked polymorphic region (5-HTTLPR), and pharmacological response to SSRIs. Given the heterogeneity in responsiveness to serotonergic drugs across the spectrum of alcoholic subtypes, we assess the contribution of specific 5-HT circuits to discrete endophenotypes of alcohol dependence. 5-HT circuits play a distinctive role in reward, stress, and executive function which may account for the variation in response to serotonergic drugs. New optogenetic and chemogenetic methods for dissecting 5-HT circuits in alcohol dependence may provide clues leading to more effective pharmacotherapies. Although our current understanding of the role of 5-HT systems in alcohol dependence is incomplete, there is some evidence to suggest that 5-HT3 receptor antagonists are effective in people with the L/L genotype of the 5-HTTLPR polymorphism while SSRIs may be more beneficial to people with the S/L or S/S genotype. Studies that assess the impact of serotonin transporter polymorphisms on 5-HT circuit function and the subsequent development of alcohol use disorders will be an important step forward in treating alcohol dependence.

An Animal Model of Alcohol Dependence to Screen Medications for Treating Alcoholism

Despite the high prevalence of alcohol use disorders in the United States, only a relatively small percentage of those afflicted seek treatment. This is further compounded by the fact that there are too few medications available to effectively treat this significant public health problem. The need for identifying and evaluating more effective treatments that aid in preventing relapse and/or tempering risky and harmful alcohol consumption cannot be overstated. Use of animal models represents a critical step in the process of screening, identifying, and informing plans for prioritizing the most promising candidate medications that can be advanced to the next stage of evaluation (clinical laboratory paradigms and controlled clinical trials). Numerous animal models have been developed to study excessive levels of alcohol self-administration. In recent years, a large literature has amassed of studies in which rodent models of dependence have been linked with alcohol self-administration procedures. This chapter focuses on studies employing a dependence model that involves chronic exposure to alcohol vapor by inhalation, which yields in both mice and rats significant escalation of voluntary alcohol consumption. These animal models of dependence and alcohol self-administration have revealed valuable insights about underlying mechanisms that drive excessive drinking. Additionally, this preclinical approach is useful in evaluating the effects of medications on escalated drinking associated with dependence vs more stable levels displayed by nondependent animals.

Desipramine enhances the ability of paliperidone to decrease alcohol drinking

Alcohol use disorder commonly occurs in patients with schizophrenia and dramatically worsens their course. The atypical antipsychotic clozapine has been associated with reduced drinking in these patients, but its toxicity reduces its use. We have attempted to create a clozapine-like drug by combining agents that capture components of clozapine's pharmacologic action, including its weak dopamine D2 blockade and noradrenergic modulation. The current study assessed whether paliperidone, a dopamine D2 receptor and adrenergic alpha-2 receptor antagonist like clozapine, would attenuate alcohol drinking in the alcohol-preferring P rat and the Syrian golden hamster, and whether desipramine, a norepinephrine reuptake inhibitor, would potentiate the ability of paliperidone to attenuate alcohol drinking in the P rat and the Syrian golden hamster. Daily subcutaneous injections of paliperidone (5 mg/kg for the rat; 1 mg/kg for the hamster) over 20 days slightly and transiently attenuated initiation of alcohol consumption in both animals. Desipramine (3 mg/kg) or lower doses of paliperidone alone did not affect alcohol drinking. However, the combination of desipramine (3 mg/kg) and paliperidone essentially prevented initiation of alcohol drinking and acquisition of alcohol preference in the P rat (2.5 or 5 mg/kg), and almost as dramatically suppressed chronic alcohol intake and alcohol preference in the hamster (2.5 mg/kg). Taken together, the current data suggest that (1) the desipramine and paliperidone combination attenuates alcohol drinking in a synergistic manner, and (2) desipramine and paliperidone may serve as an effective new treatment for alcohol use disorder in patients with schizophrenia.

Adolescent social isolation increases anxiety-like behavior and ethanol intake and impairs fear extinction in adulthood: Possible role of disrupted noradrenergic signaling

Alcohol use disorder, anxiety disorders, and post-traumatic stress disorder (PTSD) are highly comorbid, and exposure to chronic stress during adolescence may increase the incidence of these conditions in adulthood. Efforts to identify the common stress-related mechanisms driving these disorders have been hampered, in part, by a lack of reliable preclinical models that replicate their comorbid symptomatology. Prior work by us, and others, has shown that adolescent social isolation increases anxiety-like behaviors and voluntary ethanol consumption in adult male Long-Evans rats. Here we examined whether social isolation also produces deficiencies in extinction of conditioned fear, a hallmark symptom of PTSD. Additionally, as disrupted noradrenergic signaling may contribute to alcoholism, we examined the effect of anxiolytic medications that target noradrenergic signaling on ethanol intake following adolescent social isolation. Our results confirm and extend previous findings that adolescent social isolation increases anxiety-like behavior and enhances ethanol intake and preference in adulthood. Additionally, social isolation is associated with a significant deficit in the extinction of conditioned fear and a marked increase in the ability of noradrenergic therapeutics to decrease ethanol intake. These results suggest that adolescent social isolation not only leads to persistent increases in anxiety-like behaviors and ethanol consumption, but also disrupts fear extinction, and as such may be a useful preclinical model of stress-related psychopathology. Our data also suggest that disrupted noradrenergic signaling may contribute to escalated ethanol drinking following social isolation, thus further highlighting the potential utility of noradrenergic therapeutics in treating the deleterious behavioral sequelae associated with early life stress.

Memantine reduces alcohol drinking but not relapse in alcohol-dependent rats

Alcoholism is a chronic relapsing disorder with consequences on health and that requires more effective treatments. Among alternative therapies, the therapeutic potential of the non-competitive N-methyl-D-aspartate receptor antagonist memantine has been suggested. Despite promising results, its efficiency in the treatment of alcoholism remains controversial. Currently, there is no pre-clinical data regarding its effects on the motivation for ethanol in post-dependent (PD) animals exposed to intermittent ethanol vapor, a validated model of alcoholism. Thus, the objectives of this study were to evaluate the effects of acute injections of memantine (0, 12.5, 25 and 50 mg/kg) on operant ethanol self-administration in non-dependent (ND) and PD rats tested either during acute withdrawal or relapse after protracted abstinence. Our results showed that memantine (25 mg/kg) abolished ethanol self-administration in ND rats and reduced by half the one of PD rats during acute withdrawal. While this effect was observed only 6 hours after treatment in ND rats, it was long lasting in PD rats (at least 30 hours after injection). Furthermore, our results indicated that memantine did not modify the breaking point for ethanol. This suggests that memantine probably act by potentiating the pharmacological effect of ethanol but not by reducing motivation for ethanol. Finally, memantine was also ineffective in reducing relapse after protracted abstinence. Altogether, our pre-clinical results highlighted a potential therapeutic use of memantine that may be used as a replacement therapy drug but not as relapse-preventing drug.

The histone deacetylase inhibitor sodium butyrate decreases excessive ethanol intake in dependent animals

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.

Triple monoamine uptake inhibitors demonstrate a pharmacologic association between excessive drinking and impulsivity in high-alcohol-preferring (HAP) mice

Approximately 30% of current drinkers in the United States drink excessively, and are referred to as problem/hazardous drinkers. These individuals, who may not meet criteria for alcohol abuse or dependence, comprise binge, heavy drinkers, or both. Given their high prevalence, interventions that reduce the risk of binge and heavy drinking have important public health implications. Impulsivity has been repeatedly associated with excessive drinking in the clinical literature. As impulsivity is correlated with, and may play a critical role in, the initiation and maintenance of excessive drinking, this behavior may be an important target for therapeutic intervention. Hence, a better understanding of pharmacological treatments capable of attenuating excessive drinking and impulsivity may markedly improve clinical outcomes. The high-alcohol-preferring (HAP) mice represent a strong rodent model to study the relationship between impulsivity and excessive alcohol drinking, as recent evidence indicates they consume high levels of alcohol throughout their active cycle and are innately impulsive. Using this model, the present study demonstrates that the triple monoamine uptake inhibitors (TUIs) amitifadine and DOV 102, 677 effectively attenuate binge drinking, heavy drinking assessed via a 24-hour free-choice assay, and impulsivity measured by the delay discounting procedure. In contrast, 3-PBC, a GABA-A α1 preferring ligand with mixed agonist-antagonist properties, attenuates excessive drinking without affecting impulsivity. These findings suggest that in HAP mice, monoamine pathways may predominate as a common mechanism underlying impulsivity and excessive drinking, while the GABAergic system may be more salient in regulating excessive drinking. We further propose that TUIs such as amitifadine and DOV 102, 677 may be used to treat the co-occurrence of impulsivity and excessive drinking.

Postdependent state in rats as a model for medication development in alcoholism

Rational development of novel therapeutic strategies for alcoholism requires understanding of its underlying neurobiology and pathophysiology. Obtaining this knowledge largely relies on animal studies. Thus, choosing the appropriate animal model is one of the most critical steps in pre-clinical medication development. Among the range of animal models that have been used to investigate excessive alcohol consumption in rodents, the postdependent model stands out. It was specifically developed to test the role of negative affect as a key driving force in a perpetuating addiction cycle for alcoholism. Here, we will describe our approach to make rats dependent via chronic intermittent exposure to alcohol, discuss the validity of this model, and compare it with other commonly used animal models of alcoholism. We will summarize evidence that postdependent rats fulfill several criteria of a 'Diagnostic and Statistical Manual of Mental Disorders IV/V-like' diagnostic system. Importantly, these animals show long-lasting excessive consumption of and increased motivation for alcohol, and evidence for loss of control over alcohol intake. Our conclusion that postdependent rats are an excellent model for medication development for alcoholism is underscored by a summary of more than two dozen pharmacological tests aimed at reversing these abnormal alcohol responses. We will end with open questions on the use of this model. In the tradition of the Sanchis-Segura and Spanagel review, we provide comic strips that illustrate the postdependent procedure and relevant phenotypes in this review.

Convergent pharmacological mechanisms in impulsivity and addiction: insights from rodent models

Research over the last two decades has widely demonstrated that impulsivity, in its various forms, is antecedent to the development of drug addiction and an important behavioural trait underlying the inability of addicts to refrain from continued drug use. Impulsivity describes a variety of rapidly and prematurely expressed behaviours that span several domains from impaired response inhibition to an intolerance of delayed rewards, and is a core symptom of attention deficit hyperactivity disorder (ADHD) and other brain disorders. Various theories have been advanced to explain how impulsivity interacts with addiction both causally and as a consequence of chronic drug abuse; these acknowledge the strong overlaps in neural circuitry and mechanisms between impulsivity and addiction and the seemingly paradoxical treatment of ADHD with stimulant drugs with high abuse potential. Recent years have witnessed unprecedented progress in the elucidation of pharmacological mechanisms underpinning impulsivity. Collectively, this work has significantly improved the prospect for new therapies in ADHD as well as our understanding of the neural mechanisms underlying the shift from recreational drug use to addiction. In this review, we consider the extent to which pharmacological interventions that target impulsive behaviour are also effective in animal models of addiction. We highlight several promising examples of convergence based on empirical findings in rodent-based studies.

Desipramine enhances the ability of risperidone to decrease alcohol intake in the Syrian golden hamster

The atypical antipsychotic clozapine reduces alcohol drinking in patients with schizophrenia. We have proposed that clozapine׳s ability to decrease alcohol drinking relates to its weak blockade of the dopamine D2 receptor and potent blockade of the norepinephrine α-2 receptor, as well as its ability to elevate plasma and brain norepinephrine. Another atypical antipsychotic, risperidone, which is a potent blocker of both the dopamine D2 receptor and norepinephrine α-2 receptor, does not decrease alcohol drinking. In this study, we used the Syrian golden hamster to test whether the ability of risperidone to reduce alcohol drinking would be enhanced if it was used in combination with the norepinephrine reuptake inhibitor desipramine. Hamsters were given free access to water and alcohol (15% v/v) until they reached a steady drinking baseline. They were then treated daily with each drug or drug combination for 20 days. Risperidone (0.2mg/kg) only transiently decreased alcohol drinking. However, 5.0mg/kg, and possibly 1.0mg/kg, desipramine added to 0.2mg/kg risperidone appeared to produce a more substantial and relatively sustained effect than risperidone alone. Data from this study provide leads toward the development of new treatments for patients with schizophrenia and alcoholism, and also for those with alcoholism alone.

Chronic treatment with prazosin or duloxetine lessens concurrent anxiety-like behavior and alcohol intake: evidence of disrupted noradrenergic signaling in anxiety-related alcohol use

BACKGROUND

Alcohol use disorders have been linked to increased anxiety, and enhanced central noradrenergic signaling may partly explain this relationship. Pharmacological interventions believed to reduce the excitatory effects of norepinephrine have proven effective in attenuating ethanol intake in alcoholics as well as in rodent models of ethanol dependence. However, most preclinical investigations into the effectiveness of these drugs in decreasing ethanol intake have been limited to acute observations, and none have concurrently assessed their anxiolytic effects. The purpose of these studies was to examine the long-term effectiveness of pharmacological interventions presumed to decrease norepinephrine signaling on concomitant ethanol self-administration and anxiety-like behavior in adult rats with relatively high levels of antecedent anxiety-like behavior.

METHODS

Adult male Long-Evans rats self-administered ethanol on an intermittent access schedule for eight to ten weeks prior to being implanted with osmotic minipumps containing either an a1-adrenoreceptor antagonist (prazosin, 1.5 mg/kg/day), a β1/2-adrenoreceptor antagonist (propranolol, 2.5 mg/kg/day), a serotonin/norepinephrine reuptake inhibitor (duloxetine, 1.5 mg/kg/day) or vehicle (10% dimethyl sulfoxide). These drugs were continuously delivered across four weeks, during which animals continued to have intermittent access to ethanol. Anxiety-like behavior was assessed on the elevated plus maze before treatment and again near the end of the drug delivery period.

RESULTS

Our results indicate that chronic treatment with a low dose of prazosin or duloxetine significantly decreases ethanol self-administration (P < 0.05). Furthermore, this decrease in drinking is accompanied by significant reductions in the expression of anxiety-like behavior (P < 0.05).

CONCLUSIONS

These findings suggest that chronic treatment with putative inhibitors of central noradrenergic signaling may attenuate ethanol intake via a reduction in anxiety-like behavior.

Deciphering the relationship between vulnerability to ethanol-induced behavioral sensitization and ethanol consumption in outbred mice

Ethanol (EtOH)-induced behavioral sensitization (EIBS) is proposed to play a role in early and recurring steps of alcohol dependence, but its impact on alcohol abuse is not clear. EIBS development is dependent upon animal species, strain and also individual factors. We proposed here to decipher the co-expression of EIBS and EtOH intake in individual animals among outbred Swiss mice, which exhibit heterogeneity that parallels what may occur in humans. To do so, mice were exposed to a two-bottle choice with free access to water or 10% EtOH for 6 days just before and immediately after chronic intraperitoneal 2.5 g/kg ethanol injections once a day for 10 consecutive days. Based on their sensitization scores, mice were split into resistant and sensitized animals. First, we showed that individual susceptibility to EIBS is inversely correlated with voluntary EtOH consumption. Exposure to repeated EtOH during EIBS development increased subsequent EtOH intake among the entire population. Very interestingly, subsequent analyses suggested that the less the mice are sensitized the more they increase their EtOH intake; however, resistant mice were sensitive to EtOH adulteration with quinine, whereas sensitized ones maintained their EtOH intake levels, therefore exhibiting a compulsive-like drinking pattern. In addition, we showed that resistant mice do not exhibit a weaker sensitivity to the aversive properties of EtOH that may contribute to their higher level of EtOH intake compared to sensitized mice. This study confirms and extends previous data showing a deep relationship between propensity for EtOH consumption and susceptibility to EIBS in Swiss mice.

Neurochemical mechanisms of alcohol withdrawal

Alcohol dependence encompasses a serious medical and societal problem that constitutes a major public health concern. A serious consequence of dependence is the emergence of symptoms associated with the alcohol withdrawal syndrome when drinking is abruptly terminated or substantially reduced. Clinical features of alcohol withdrawal include signs of central nervous system hyperexcitability, heightened autonomic nervous system activation, and a constellation of symptoms contributing to psychologic discomfort and negative affect. The development of alcohol dependence is a complex and dynamic process that ultimately reflects a maladaptive neurophysiologic state. Perturbations in a wide range of neurochemical systems, including glutamate, γ-aminobutyric acid, monoamines, a host of neuropeptide systems, and various ion channels produced by the chronic presence of alcohol ultimately compromise the functional integrity of the brain. These neuroadaptations not only underlie the emergence and expression of many alcohol withdrawal symptoms, but also contribute to enhanced relapse vulnerability as well as perpetuation of uncontrolled excessive drinking. This chapter highlights the hallmark features of the alcohol withdrawal syndrome, and describes neuroadaptations in a wide array of neurotransmitter and neuromodulator systems (amino acid and monoamine neurotransmitter, neuropeptide systems, and various ion channels) as they relate to the expression of various signs and symptoms of alcohol withdrawal, as well as their relationship to the significant clinical problem of relapse and uncontrolled dangerous drinking.

Increased alcohol consumption in rats after subchronic antidepressant treatment

The use of antidepressants for alcoholism in humans has been a matter of controversy in recent years. Despite the existence of an important co-morbidity for depression and alcoholism, some studies suggest that the use of antidepressants could worsen the prognosis of alcoholism. However, there is a lack of studies in animal models exploring this phenomenon. In the present study, we show how the 15-d treatment with fluoxetine (10 mg/kg) or venlafaxine (50 mg/kg) affected alcohol deprivation effect (ADE) and subsequent alcohol consumption. Initially, fluoxetine reduced ADE and venlafaxine did not affect it. However, in the following days, both antidepressants increased alcohol consumption, an effect that was found to last at least 5 wk. Fluoxetine treatment was shown to cause a locomotor sensitized response to a challenge dose of amphetamine (0.5 mg/kg), indicating the presence of a supersensitive dopaminergic transmission. In summary, antidepressant treatment may increase alcohol consumption in rats after a period of alcohol deprivation and this could be related to alterations in the reward circuitry. This finding confirms in an animal model previous reports in humans that may limit the use of antidepressants for alcoholism.

The adenosine A2A receptor agonist CGS 21680 decreases ethanol self-administration in both non-dependent and dependent animals

There is emerging evidence that the adenosinergic system might be involved in drug addiction and alcohol dependence. We have already demonstrated the involvement of A2A receptors (A2AR) in ethanol-related behaviours in mice. Here, we investigated whether the A2AR agonist CGS 21680 can reduce ethanol operant self-administration in both non-dependent and ethanol-dependent Wistar rats. To rule out a potential involvement of the A1R in the effects of CGS 21680, we also tested its effectiveness to reduce ethanol operant self-administration in both heterozygous and homozygous A1R knockout mice. Our results demonstrated that CGS 21680 (0.065, 0.095 and 0.125 mg/kg, i.p.) had a bimodal effect on 10% ethanol operant self-administration in non-dependent rats. The intermediate dose was also effective in reducing 2% sucrose self-administration. Interestingly, the intermediate dose reduced 10% ethanol self-administration in dependent animals more effectively (75% decrease) when compared with non-dependent animals (57% decrease). These results suggest that the A2AR are involved in CGS 21680 effects since the reduction of ethanol self-administration was not dependent upon the presence of A1R in mice. In conclusion, our findings demonstrated the effectiveness of the A2AR agonist CGS 21680 in a preclinical model of alcohol addiction and suggested that the adenosinergic pathway is a promising target to treat alcohol addiction.

Blockade of ethanol-induced behavioral sensitization by sodium butyrate: descriptive analysis of gene regulations in the striatum

BACKGROUND

Behavioral sensitization induced by repeated ethanol (EtOH) exposure may play a critical role in the development of alcohol dependence. Because recent data demonstrate that histone deacetylase inhibitor (HDACi) may be of interest in the treatment of addiction, we explored the effect of the HDACi sodium butyrate (NaB) on EtOH-induced behavioral sensitization (EIBS) in DBA/2J mice. We also investigated gene regulations in the striatum of sensitized mice using epigenetic- and signal transduction-related PCR arrays.

METHODS

Mice were injected with saline or EtOH (0.5 to 2.5 g/kg) once a day for 10 days. Mice received NaB (200 to 600 mg/kg) 30 minutes before each injection (prevention protocol) or once daily between days 11 and 16 (reversal protocol). At day 17, brains were removed 30 minutes after a saline or EtOH challenge to assess gene and proteins levels.

RESULTS

Only the intermediate EtOH doses (1.0 and 2.0 g/kg) were effective in inducing EIBS, and both doses were associated with specific gene regulations in the striatum. The induction of sensitization by 1.0 g/kg (but not 2.0 g/kg) EtOH was dose-dependently prevented or reversed by NaB. Among the 168 studied genes, EIBS blockade was associated with specific gene regulations (bcl-2, bdnf, hdac4, pak1, penk, tacr1, vip…) and changes in brain-derived neurotrophic factor in both striatum and prefrontal cortex.

CONCLUSIONS

These results indicate that EIBS is associated with specific gene regulations in the striatum depending on the EtOH dose and that NaB can be useful in blocking some long-lasting neuro-adaptations to repeated EtOH administrations.

Alcohol intoxications during adolescence increase motivation for alcohol in adult rats and induce neuroadaptations in the nucleus accumbens

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.

Desipramine protects neuronal cell death and induces heme oxygenase-1 expression in Mes23.5 dopaminergic neurons

BACKGROUND

Desipramine is known principally as a tricyclic antidepressant drug used to promote recovery of depressed patients. It has also been used in a number of other psychiatric and medical conditions. The present study is the first to investigate the neuroprotective effect of desipramine.

METHODOLOGY/PRINCIPAL FINDINGS

Mes23.5 dopaminergic cells were used to examine neuroprotective effect of desipramine. Western blot, reverse transcription-PCR, MTT assay, siRNA transfection and electrophoretic mobility shift assay (EMSA) were carried out to assess the effects of desipramine. Desipramine induces endogenous anti-oxidative enzyme, heme oxygenase-1 (HO-1) protein and mRNA expression in concentration- and time-dependent manners. A different type of antidepressant SSRI (selective serotonin reuptake inhibitor), fluoxetine also shows similar effects of desipramine on HO-1 expression. Moreover, desipramine induces HO-1 expression through activation of ERK and JNK signaling pathways. Desipramine also increases NF-E2-related factor-2 (Nrf2) accumulation in the nucleus and enhances Nrf2-DNA binding activity. Moreover, desipramine-mediated increase of HO-1 expression is reduced by transfection with siRNA against Nrf2. On the other hand, pretreatment of desipramine protects neuronal cells against rotenone- and 6-hydroxydopamine (6-OHDA)-induced neuronal death. Furthermore, inhibition of HO-1 activity by a HO-1 pharmacological inhibitor, ZnPP IX, attenuates the neuroprotective effect of desipramine. Otherwise, activation of HO-1 activity by HO-1 activator and inducer protect 6-OHDA-induced neuronal death.

CONCLUSIONS/SIGNIFICANCE

These findings suggest that desipramine-increased HO-1 expression is mediated by Nrf2 activation through the ERK and JNK signaling pathways. Our results also suggest that desipramine provides a novel effect of neuroprotection, and neurodegenerative process might play an important role in depression disorder.

The effects of methamphetamine self-administration on behavioural sensitization in the olfactory bulbectomy rat model of depression

Depression is frequently comorbid with a drug addiction and may seriously complicate its treatment. Currently, there is no routinely used animal model to investigate this comorbidity. In this study the effect of repeated administration of methamphetamine on i.v. drug self-administration in an olfactory bulbectomy model of depression in rats was investigated in order to propose and validate a rat model of comorbid depression and addiction. Male Wistar rats were either olfactory-bulbectomized (OBX) or sham-operated. They subsequently underwent a methamphetamine sensitization regime, which consisted of daily i.p. injections of methamphetamine for a 14-d period; controls received Sal injections at the same frequency. The i.v. self-administration of methamphetamine (0.08 mg/kg in one infusion) paradigm on a fixed ratio schedule of reinforcement was performed using operant chambers. A significant decrease of the drug intake was recorded in sham-operated animals pretreated with methamphetamine when compared to the unpretreated group. This was not apparent in the OBX groups. Both groups of OBX animals exhibited a higher intake of methamphetamine compared to the corresponding sham-operated groups, thus confirming the hypothesis of higher drug intake in depressive conditions in this rodent model. The procedure of behavioural sensitization to methamphetamine decreased the number of self-administered drug doses per session in the sham-operated rats. It is hypothesized that this phenomenon resulted from increasing efficacy of the drug after behavioural sensitization caused by repeated methamphetamine intermittent administration.

Amitifadine, a triple monoamine uptake inhibitor, reduces binge drinking and negative affect in an animal model of co-occurring alcoholism and depression symptomatology

The co-occurrence of alcoholism and depression is highly prevalent and difficult to treat. In an animal model of binge drinking that exhibits abstinence-induced behaviors reminiscent of negative affective states, the triple monoamine uptake inhibitor, amitifadine, produced a selective, dose dependent attenuation of binge drinking. Amitifadine also reversed abstinence-induced increases in the intracranial self-stimulation threshold, a model of anhedonia, and immobility in the forced swim test, reflecting behavioral despair. In view of the safety profile of amitifadine in humans, including low risk for weight gain, lack of sexual side effects, and low potential for abuse, we hypothesize that amitifadine will be effective in treating co-occurring alcoholism and depression.

Expression of ethanol-induced behavioral sensitization is associated with alteration of chromatin remodeling in mice

BACKGROUND

Ethanol-induced behavioral sensitization (EIBS) is proposed to play a role in early and recurring steps of addiction. EIBS does not occur uniformly in all animals even from the same inbred strain. Since recent data demonstrate that epigenetic mechanisms are likely to be involved in the development and the persistence of ethanol-related behaviors, we explored the involvement of epigenetic mechanisms in ethanol response after EIBS development.

METHODOLOGY

DBA/2J mice were i.p. injected with saline or ethanol (2 g/kg) once a day for 10 consecutive days. At day 17, ethanol-treated mice were split in resistant and sensitized groups. Brains were then removed 30 min after a saline or 2 g/kg ethanol challenge to assess i) gene expression using PCR array targeting 84 epigenetic-related genes and ii) histone deacetylases (HDAC), histone acetylases (HAT) and DNA methyltransferases (DNMT) activities as well as H4K12 acetylation.

PRINCIPAL FINDINGS

Acute ethanol administration decreased dnmt1, esco2 and rps6ka5 genes expression. These genes were similarly altered in sensitized but not in resistant mice after an ethanol challenge, suggesting that resistant mice were tolerant to the transcriptional outcomes of an ethanol challenge. Whereas global HAT or DNMT activity was not affected, global HDAC activity was reduced after an acute ethanol injection. HDAC inhibition occurred in all ethanol-treated mice but with a lesser extent in sensitized animals. As a consequence, H4 acetylation was specifically potentiated in the core of the Nac proportionally to the striatal HDAC activity decrease.

CONCLUSIONS/SIGNIFICANCE

The present study highlights that the contrasted behavioral response to an ethanol challenge between resistant and sensitized mice may be mediated by epigenetic mechanisms occurring specifically in the striatum. Here we show that vulnerability to ethanol dependence and relapse could be, at least in part, due to individual variability in acute ethanol-induced epigenetic response.

Introduction to the special issue "Pharmacotherapies for the treatment of alcohol abuse and dependence" and a summary of patents targeting other neurotransmitter systems

This paper introduces the Special Section: Pharmacotherapies for the Treatment of Alcohol Abuse and Dependence and provides a summary of patents targeting neurotransmitter systems not covered in the other four chapters. The World Health Organization notes that alcoholic-type drinking results in 2.5 million deaths per year, and these deaths occur to a disproportionately greater extent among adolescents and young adults. Developing a pharmacological treatment targeting alcohol abuse and dependence is complicated by (a) the heterogeneous nature of the disease(s), (b) alcohol affecting multiple neurotransmitter and neuromodulator systems, and (c) alcohol affecting multiple organ systems which in turn influence the function of the central nervous system. Presently, the USA Federal Drug Administration has approved three pharmacotherapies for alcoholism: disulfiram, naltrexone, and acamprosate. This chapter provides a summary of the following systems, which are not covered in the accompanying chapters; alcohol and acetaldehyde metabolism, opioid, glycinergic, GABA-A, neurosteroid, dopaminergic, serotonergic, and endocannabinoid, as well as patents targeting these systems for the treatment of alcoholism. Finally, an overview is presented on the use of pharmacogenetics and pharmacogenomics in tailoring treatments for certain subpopulations of alcoholics, which is expected to continue in the future.

Chronic and intermittent exposure to alcohol vapors: a new model of alcohol-induced osteopenia in the rat

BACKGROUND

Different models are used to study the effects of chronic alcohol consumption on bone tissue in the rat. However, the current models take several months to show indices of osteopenia as observed in chronic drinkers. Numerous studies have supported that chronic and intermittent exposure to ethanol vapors has predictive validity as a model of alcohol dependence in humans. However, this model has never been applied to bone research to study its effects on the parameters that define osteopenia. This was the goal of this study in the rat.

METHODS

Male Wistar rats were exposed to ethanol vapor inhalation (n = 6) or air (controls, n = 6). Animals were exposed to chronic (11 weeks) and intermittent (14 hours a day) ethanol vapor reaching stable blood alcohol levels (BALs; 150 to 250 mg/dl) at the end of the third week of inhalation. After the sacrifice, right and left femur and tibia were dissected free of fat and connective tissue and bone mineral density (BMD) was assessed by dual X-ray absorptiometry. The microarchitecture of the femur was studied using microcomputed tomography.

RESULTS

The BMD of the left and right femurs and the left tibia was lower in the ethanol group compared with the control group. The bone volume fraction (BV/TV) and the bone surface density (BS/TV) were lower in the ethanol group compared with control animals. The trabecular number (Tb.N) was lower in the ethanol group while the trabecular spacing was higher.

CONCLUSIONS

The decrease in the BMD, BV/TV, and Tb.N is in the same range as what is observed in human drinkers and what is reported with other animal alcohol models (Lieber-DeCarli liquid diet, ethanol in the tap water). Therefore, this model could be useful to study the effects of chronic alcohol consumption in the bone research field and has the advantage of controlling easily targeted BALs.

Effects of the triple monoamine uptake inhibitor DOV 102,677 on alcohol-motivated responding and antidepressant activity in alcohol-preferring (P) rats

BACKGROUND

  Concurrent inhibitors of dopamine, norepinephrine, and serotonin uptake have been proposed as novel antidepressants. Given the high comorbidity between alcoholism and depression, we evaluated the activity of DOV 102,677 (DOV) on alcohol-maintained responding and performance in the forced swim test (FST), a model of antidepressant (AD) activity, using alcohol-preferring (P) rats.

METHODS

  Following training to lever press for either alcohol (10% v/v) or sucrose (3, 2%, w/v) on a fixed-ratio 4 (FR4) schedule, DOV (1.56 to 50 mg/kg; PO) was given 25 minutes or 24 hours prior to evaluation. The effects of DOV (12.5 to 50 mg/kg; PO) in the FST were evaluated 25 minutes posttreatment.

RESULTS

  DOV (6.25 to 50 mg/kg) dose-dependently reduced alcohol-maintained responding by 59 to 88% at 25 minutes posttreatment, without significantly altering sucrose responding. The reduction in alcohol responding (44% at 50 mg/kg) was sustained for up to 120 hours after a single dose. Administration of a single dose of DOV (25, 50 mg/kg) 24 hours before testing suppressed alcohol responding for 48 hours by 59 to 62%. DOV (12.5 to 50 mg/kg) also dose-dependently reduced immobility of P rats in the FST.

CONCLUSIONS

  DOV produces both prolonged and selective reductions of alcohol-motivated behaviors in P rats. The elimination kinetics of DOV suggests that its long duration of action may be due to an active metabolite. DOV also produced robust AD-like effects in P rats. We propose that DOV may be useful in treating comorbid alcoholism and depression in humans.