Acamprosate: recent findings and future research directions

Acamprosate reduces ethanol intake in the rat by a combined action of different drug components

Alcohol misuse accounts for a sizeable proportion of the global burden of disease, and Campral® (acamprosate; calcium-bis-(N-acetylhomotaurinate)) is widely used as relapse prevention therapy. The mechanism underlying its effect has in some studies been attributed to the calcium moiety and not to the N-acetylhomotaurine part of the compound. We recently suggested that the dopamine elevating effect of acamprosate is mediated both by N-acetylhomotaurine and calcium in a glycine receptor dependent manner. Here we aimed to explore, by means of in vivo microdialysis, if our previous study using local administration was functionally relevant and if systemic administration of the sodium salt of N-acetylhomotaurine (sodium acamprosate; 200 mg/kg, i.p.) enhanced the effects of calcium chloride (CaCl2; 73.5 mg/kg, i.p.) on nucleus accumbens (nAc) dopamine and/or taurine levels in male Wistar rats. In addition, we investigated the impact of regular acamprosate and the combination of CaCl2 and N-acetylhomotaurine on the alcohol deprivation effect (ADE). Finally, we assessed if N-acetylhomotaurine potentiates the ethanol-intake reducing effect of CaCl2 in a two-bottle choice voluntary ethanol consumption model followed by an ADE paradigm. Systemic administration of regular acamprosate, sodium acamprosate and CaCl2 all trended to increase nAc dopamine whereas the combination of CaCl2 and sodium acamprosate produced a significant increase. Sodium acamprosate elevated extracellular taurine levels without additional effects of CaCl2. Ethanol intake was significantly reduced by systemic administration of CaCl2 without additional effects of the combination of CaCl2 and sodium acamprosate. Both acamprosate and CaCl2 combined with sodium acamprosate blocked the ADE following acute treatment. The data presented suggest that CaCl2 and N-acetylhomotaurine act in concert on a neurochemical level, but calcium appears to have the predominant effect on ethanol intake.

Medications for treating alcohol use disorder: A narrative review

Chronic heavy alcohol use impacts all major neurotransmitter systems and is associated with multiple medical, psychiatric, and social problems. Available evidence-based medications to treat alcohol use disorder (AUD) are underutilized in clinical practice. These medications promote abstinence or reduce alcohol consumption, though there are questions regarding their optimal dosage, length of treatment, and utility in combination with one another. Pharmacogenetic approaches, which use a patient's genetic make-up to inform medication selection, have garnered great interest but have yet to yield results robust enough to incorporate them in routine clinical care. This narrative review summarizes the evidence both for medications approved by the Food and Drug Administration (disulfiram, oral naltrexone, acamprosate, and extended-release naltrexone) and those commonly used off-label (e.g., gabapentin, baclofen, and topiramate) for AUD treatment. We discuss these drugs' mechanisms of action, clinical use, pharmacogenetic findings, and treatment recommendations. We conclude that the most consistent evidence supporting the pharmacotherapy of AUD is for the opioid antagonists, naltrexone and nalmefene (which is not approved in the United States), and topiramate. These medications demonstrate consistent small or moderate effects in reducing the frequency of drinking and/or heavy drinking. Lastly, we make suggestions for research needed to refine and expand the current literature on effective pharmacotherapy for AUD.

A Review of the Characteristics of Clinical Trials and Potential Medications for Alcohol Dependence: Data Analysis from ClinicalTrials.gov

Objective. This study provides a comprehensive analysis of the characteristics of clinical trials related to alcohol dependence that are registered on ClinicalTrials.gov. Methods. All ClinicalTrials.gov trials registered up to 1 January 2023 were examined, focusing on trials that involved alcohol dependence. All 1295 trials were summarized by presenting their characteristics and results and reviewed most intervention drugs used in the treatment of alcohol dependence. Results. The study analysis identified a total of 1295 clinical trials registered on ClinicalTrials.gov that were focused on alcohol dependence. Of these, 766 trials had been completed, representing 59.15% of the total, while 230 trials were currently recruiting participants, accounting for 17.76% of the total. None of the trials had yet been approved for marketing. The majority of the studies included in this analysis were interventional studies (1145 trials, or 88.41%), which accounted for most of the patients enrolled in the trials. In contrast, observational studies represented only a small portion of the trials (150 studies, or 11.58%) and involved a smaller number of patients. In terms of geographic distribution, the majority of registered studies were located in North America (876 studies, or 67.64%), while only a small number of studies were registered in South America (7 studies, or 0.54%). Conclusions. The purpose of this review is to provide a basis for the treatment of alcohol dependence and prevention of its onset through an overview of clinical trials registered at ClinicalTrials.gov. It also offers essential information for future research to guide future studies.

Alcohol-Related Liver Disease in the Covid-19 Era: Position Paper of the Italian Society on Alcohol (SIA)

BACKGROUND

Coronavirus Disease 2019 (COVID-19), firstly reported in China last November 2019, became a global pandemic. It has been shown that periods of isolation may induce a spike in alcohol use disorder (AUD). In addition, alcohol-related liver disease (ALD) is the most common consequence of excessive alcohol consumption worldwide. Moreover, liver impairment has also been reported as a common manifestation of COVID-19.

AIMS

The aim of our position paper was to consider some critical issues regarding the management of ALD in patients with AUD in the era of COVID-19.

METHODS

A panel of experts of the Italian Society of Alcohology (SIA) met via "conference calls" during the lockdown period to draft the SIA's criteria for the management of ALD in patients with COVID-19 as follows: (a) liver injury in patients with ALD and COVID-19 infection; (b) toxicity to the liver of the drugs currently tested to treat COVID-19 and the pharmacological interaction between medications used to treat AUD and to treat COVID-19; (c) reorganization of the management of compensated and decompensated ALD and liver transplantation in the COVID-19 era.

RESULTS AND CONCLUSIONS

The COVID-19 pandemic has rapidly carried us toward a new governance scenario of AUD and ALD which necessarily requires an in-depth review of the management of these diseases with a new safe approach (management of out-patients and in-patients following new rules of safety, telemedicine, telehealth, call meetings with clinicians, nurses, patients, and caregivers) without losing the therapeutic efficacy of multidisciplinary treatment.

Prospects for new drugs to treat binge-eating disorder: Insights from psychopathology and neuropharmacology

BACKGROUND

Binge-eating disorder (BED) is a common psychiatric condition with adverse psychological and metabolic consequences. Lisdexamfetamine (LDX) is the only approved BED drug treatment. New drugs to treat BED are urgently needed.

METHODS

A comprehensive review of published psychopathological, pharmacological and clinical findings.

RESULTS

The evidence supports the hypothesis that BED is an impulse control disorder with similarities to ADHD, including responsiveness to catecholaminergic drugs, for example LDX and dasotraline. The target product profile (TPP) of the ideal BED drug combines treating the psychopathological drivers of the disorder with an independent weight-loss effect. Drugs with proven efficacy in BED have a common pharmacology; they potentiate central noradrenergic and dopaminergic neurotransmission. Because of the overlap between pharmacotherapy in attention deficit hyperactivity disorder (ADHD) and BED, drug-candidates from diverse pharmacological classes, which have already failed in ADHD would also be predicted to fail if tested in BED. The failure in BED trials of drugs with diverse pharmacological mechanisms indicates many possible avenues for drug discovery can probably be discounted.

CONCLUSIONS

(1) The efficacy of drugs for BED is dependent on reducing its core psychopathologies of impulsivity, compulsivity and perseveration and by increasing cognitive control of eating. (2) The analysis revealed a large number of pharmacological mechanisms are unlikely to be productive in the search for effective new BED drugs. (3) The most promising areas for new treatments for BED are drugs, which augment noradrenergic and dopaminergic neurotransmission and/or those which are effective in ADHD.

Clinical management of the alcohol withdrawal syndrome

Up to half of individuals with a history of long-term, heavy alcohol consumption will experience the alcohol withdrawal syndrome (AWS) when consumption is significantly decreased or stopped. In its most severe form, AWS can be life-threatening. Medically assisted withdrawal (MAW) often forms the first part of a treatment pathway. This clinical review discusses key elements of the clinical management of MAW, necessary adjustments for pregnancy and older adults, likely outcome of an episode of MAW, factors that might prevent completion of the MAW process and ways of overcoming barriers to ongoing treatment of alcohol use disorder. The review also discusses the use of benzodiazepines in MAW. Although there is clear evidence for their use, benzodiazepines have been associated with abuse liability, blunting of cognition, interactions with depressant drugs, craving, delirium, dementia and disrupted sleep patterns. Because glutamatergic activation and glutamate receptor upregulation contribute to alcohol withdrawal, anti-glutamatergic strategies for MAW and other potential treatment innovations are also considered.

Behavioral Problems in Fragile X Syndrome: A Review of Clinical Management

Fragile X syndrome (FXS) is noted to be the leading cause of inherited intellectual disabilities and is caused by expansive cytosine-guanine-guanine (CGG) trinucleotide repeats in the fragile X mental retardation 1 gene (FMR1). FXS can display a wide range of behavioral problems in addition to intellectual and developmental issues. Management of these problems includes both pharmacological and non-pharmacological options and research on these different management styles has been extensive in recent years. This narrative review aimed to collate recent evidence on the various management options of behavioral problems in FXS, including the pharmacological and non-pharmacological treatments, and also to provide a review of the newer avenues in the FXS treatment.

What pharmacological interventions are effective in binge-eating disorder? Insights from a critical evaluation of the evidence from clinical trials

Binge-eating disorder (BED) is the commonest eating disorder and an important causal factor in obesity. Lisdexamfetamine is the only approved pharmacological treatment. Many drugs have been clinically evaluated and several were described as potentially promising treatments. A comprehensive reassessment of the evidence from these clinical trials has been performed. The questions to be answered were: (1) Does the evidence support claims of efficacy? (2) What pharmacological mechanisms show promise for developing new BED drugs? (3) What are the clinical implications for treating BED? PubMed and internal database searches identified every available published drug trial in BED. The trials and their results were summarised and reviewed to re-evaluate the evidence. Factors taken into consideration included psychiatric diagnosis, primary endpoint, secondary outcome measures, trial size, blinding and controls, drop-out rates, placebo response rates and weight-loss. Drugs were classified according to their pharmacology and therapeutic indication to determine which mechanisms were effective and to provide insights into the psychopathology of BED. For most drugs, robust evidence of efficacy in BED is insubstantial or absent. Some catecholaminergic drugs developed for ADHD are also effective in BED; other pharmacological mechanisms are weakly efficacious at best. Reducing BED severity has little impact on weight. Conversely, weight-loss from anti-obesity therapy is ineffective in ameliorating the psychopathological drivers of BED. (1) BED is a psychiatric not a metabolic disorder. (2) Weight-loss drugs are generally ineffective in BED. (3) Efficacy in BED is restricted to powerful catecholaminergic drugs. (4) Drugs acting via noradrenaline, 5-HT, GABA, carbonic anhydrase inhibition, opioid receptors and various ion channels are generally minimally effective at best. (5) Efficacy in BED is dependent on treating its core psychopathology; reducing impulsivity and compulsivity and increasing cognitive restraint over eating. (6) Obese subjects with BED may benefit from separate treatments for these two disorders.

Closing the brain-heart loop: Towards more holistic models of addiction and addiction recovery

Much research seeks to articulate the brain structures and pathways implicated in addiction and addiction recovery. Prominent neurobiological models emphasize the interplay between cortical and limbic brain regions as a main driver of addictive processes, but largely do not take into consideration sensory and visceral information streams that link context and state to the brain and behavior. Yet these brain-body information streams would seem to be necessary elements of a comprehensive model of addiction. As a starting point, we describe the overlap between one current model of addiction circuitry and the neural network that not only regulates cardiovascular system activity but also receives feedback from peripheral cardiovascular processes through the baroreflex loop. We highlight the need for neurobiological, molecular, and behavioral studies of neural and peripheral cardiovascular signal integration during the experience of internal states and environmental contexts that drive alcohol and other drug use behaviors. We end with a call for systematic, mechanistic research on the promising, yet largely unexamined benefits to addiction treatment of neuroscience-informed, adjunctive interventions that target the malleability of the cardiovascular system to alter brain processes.

The Role of the Central Amygdala in Alcohol Dependence

Alcohol dependence is a chronically relapsing disorder characterized by compulsive drug-seeking and drug-taking, loss of control in limiting intake, and the emergence of a withdrawal syndrome in the absence of the drug. Accumulating evidence suggests an important role for synaptic transmission in the central nucleus of the amygdala (CeA) in mediating alcohol-related behaviors and neuroadaptive mechanisms associated with alcohol dependence. Acute alcohol facilitates γ-aminobutyric acid (GABA)ergic transmission in the CeA via both pre- and postsynaptic mechanisms, and chronic alcohol increases baseline GABAergic transmission. Acute alcohol inhibits glutamatergic transmission via effects at N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the CeA, whereas chronic alcohol up-regulates NMDA receptor (NMDAR)-mediated transmission. Pro- (e.g., corticotropin-releasing factor [CRF]) and antistress (e.g., nociceptin/orphanin FQ, oxytocin) neuropeptides affect alcohol- and anxiety-related behaviors, and also alter the alcohol-induced effects on CeA neurotransmission. Alcohol dependence produces plasticity in these neuropeptide systems, reflecting a recruitment of those systems during the transition to alcohol dependence.

Calcium Carbonate Attenuates Withdrawal and Reduces Craving: A Randomized Controlled Trial in Alcohol-Dependent Patients

INTRODUCTION

Preclinical studies have shown that calcium seems to be the active component of the anti-craving drug acamprosate (Ca2+ bis-acetyl-homotaurinate). Clinical effects in humans have also indicated an association between increased calcium plasma concentration due to acamprosate treatment and better outcome relating to time to relapse and cumulative abstinence. In contrast, low calcium concentration in alcohol-dependent patients was related with craving for alcohol. The main goal of the trial was to investigate whether an oral calcium administration is able to affect craving, withdrawal, and relapse risk in alcohol-dependent patients.

METHODS

We conducted a single-blind, randomized, monocentric, controlled clinical two-arm trial in alcohol-dependent patients (Clinical Trials Registration: DRKS00011293). A total of 55 alcohol-dependent subjects received calcium carbonate (800 mg + 5 μg vitamin D) versus sodium bicarbonate (1,000 mg) daily during the 14 days of inpatient alcohol-withdrawal treatment.

RESULTS

Based on an intention-to-treat protocol, withdrawal intensity (assessed with CIWA-Ar) in the calcium carbonate group attenuated faster than in the sodium bicarbonate subgroup. Alcohol craving (assessed with OCDS) in the calcium carbonate subgroup was also significantly reduced versus the sodium bicarbonate subgroup.

CONCLUSION

Our data support earlier findings and show that treatment with calcium carbonate during alcohol withdrawal reduces symptoms of alcohol withdrawal as well as alcohol craving in a controlled clinical pilot study. Mode of actions will need to be determined to allow the further development of pharmacological interventions beyond Ca2+ bis-acetyl-homotaurinate.

ERR and dPECR Suggest a Link Between Neuroprotection and the Regulation of Ethanol Consumption Preference

Reconsumption of ethanol after withdrawal is a hallmark for relapse in recovering patients with alcohol use disorders. We show that the preference of Drosophila melanogaster to reconsume ethanol after abstinence shares mechanistic similarities to human behavior by feeding the antirelapse drug acamprosate to flies and reducing the ethanol consumption preference. The Drosophila cellular stress mutant hangover also reduced ethanol consumption preference. Together with the observation that an increasing number of candidate genes identified in a genome-wide association study on alcohol use disorders are involved in the regulation of cellular stress, the results suggest that cellular stress mechanisms might regulate the level of ethanol reconsumption after abstinence. To address this, we analyzed mutants of candidate genes involved in the regulation of cellular stress for their ethanol consumption level after abstinence and cellular stress response to free radicals. Since hangover encodes a nuclear RNA-binding protein that regulates transcript levels, we analyzed the interactions of candidate genes on transcript and protein level. The behavioral analysis of the mutants, the analysis of transcript levels, and protein interactions suggested that at least two mechanisms regulate ethanol consumption preference after abstinence-a nuclear estrogen-related receptor-hangover-dependent complex and peroxisomal trans-2-enoyl-CoA reductase (dPECR)-dependent component in peroxisomes. The loss of estrogen-like receptor and dPECR in neurons share a protective function against oxidative stress, suggesting that the neuroprotective function of genes might be a predictor for genes involved in the regulation of ethanol reconsumption after abstinence.

Advancing Precision Medicine for Alcohol Use Disorder: Replication and Extension of Reward Drinking as a Predictor of Naltrexone Response

Background

Precision medicine aims to identify those patients who will benefit the most from specific treatments. Recent work found large effects of naltrexone among “reward drinkers,” defined as individuals who drink primarily for the rewarding effects of alcohol. This study sought to replicate and extend these recent findings by examining whether the desire to drink mediated the effect of naltrexone among reward drinkers.

Methods

We conducted a secondary analysis of a 12‐week randomized clinical trial of daily or targeted naltrexone among problem drinkers (n = 163), with a focus on 86 individuals (n = 45 naltrexone and n = 41 placebo) who received daily medication. Interactive voice response technology was used to collect daily reports of drinking and desire to drink. Factor mixture models were used to derive reward and relief phenotypes. Moderation analyses were used to evaluate naltrexone effects, with phenotype as a moderator variable. Multilevel mediation tested average desire to drink as a mediator.

Results

Results indicated 4 phenotypes: low reward/low relief; low reward/high relief; high reward/low relief; and high reward/high relief. There was an interaction between the high reward/low relief subgroup (n = 10) and daily naltrexone versus placebo on drinks per drinking day (DPDD; p = 0.03), percent heavy drinking days (p = 0.004), and daily drinking (p = 0.02). As compared to placebo, individuals in the high reward/low relief phenotype who received daily naltrexone had significantly fewer DPDD (Cohen's d = 2.05) and had a lower proportion of heavy drinking days (Cohen's d = 1.75). As hypothesized, reductions in average desire to drink mediated the effect of naltrexone on average daily drinking among the high reward/low relief drinkers (moderated mediation effect: p = 0.029).

Conclusions

This theory‐driven study replicates the empirical finding that naltrexone is particularly efficacious among high reward/low relief drinkers. Our study brings the field a step closer to the potential of using a precision medicine approach to treating alcohol use disorder.

Investigational drugs in early-stage clinical trials for autism spectrum disorder

Introduction: Pharmacologic interventions in Autism Spectrum Disorder (ASD) have historically focused on symptom-based approaches. However, a treatment for the core social deficits has remained unidentified. While a definitive theory for the cause of ASD is not yet known, recent advances in our understanding of ASD pathophysiology have opened the door for research on new pharmaceutical methods to target core symptomology. Areas covered: Herein, we review the novel pharmacologic therapies undergoing early-stage clinical trials for the treatment of the social symptoms associated with ASD. Specifically, these strategies center on altering neurologic excitatory and inhibitory imbalance, neuropeptide abnormalities, immunologic dysfunction, and biochemical deficiencies in ASD. Expert opinion: Utilizing the growing field of knowledge regarding the pathological mechanisms and altered neurobiology of individuals with ASD has led to the development of many innovative pharmaceutical interventions. Clinical trials for neurobiologic and immunologic targets show promise in impacting the social behavior and processing deficits in ASD but need evaluation in larger clinical trials and continued biomarker development to more effectively and consistently assess pharmacologic effects. Additionally, evaluating patient-specific drug responsivity and integrating behavioral intervention in conjunction with pharmacologic treatment is crucial to developing a successful approach to ASD treatment.

Building better strategies to develop new medications in Alcohol Use Disorder: Learning from past success and failure to shape a brighter future

Alcohol Use Disorder (AUD) is a chronic disease that develops over the years. The complexity of the neurobiological processes contributing to the emergence of AUD and the neuroadaptive changes occurring during disease progression make it difficult to improve treatments. On the other hand, this complexity offers researchers the possibility to explore new targets. Over years of intense research several molecules were tested in AUD; in most cases, despite promising preclinical data, the clinical efficacy appeared insufficient to justify futher development. A prototypical example is that of corticotropin releasing factor type 1 receptor (CRF1R) antagonists that showed significant effectiveness in animal models of AUD but were largely ineffective in humans. The present article attempts to analyze the most recent venues in the development of new medications in AUD with a focus on the most promising drug targets under current exploration. Moreover, we delineate the importance of using a more integrated translational framework approach to correlate preclinical findings and early clinical data to enhance the probability to validate biological targets of interest.

Alcohol dependence treating agent, acamprosate, prevents traumatic brain injury-induced neuron death through vesicular zinc depletion

Acamprosate, also known as N-acetyl homotaurine, is an N-methyl-d-aspartate receptor antagonist that is used for treating alcohol dependence. Although the exact mechanism of acamprosate has not been clearly established, it appears to work by promoting a balance between the excitatory and inhibitory neurotransmitters, glutamate, and gamma-aminobutyric acid, respectively. Several studies have demonstrated that acamprosate provides neuroprotection against ischemia-induced brain injury. However, no studies have been performed evaluating the effect of acamprosate on traumatic brain injury (TBI). In the present study, we sought to evaluate the therapeutic potential of acamprosate to protect against neuronal death following TBI. Rats were given oral acamprosate (200 mg/kg/d for 2weeks) and then subjected to a controlled cortical impact injury localized over the parietal cortex. Histologic analysis was performed at 3hours, 24hours, and 7days after TBI. We found that acamprosate treatment reduced the concentration of vesicular glutamate and zinc in the hippocampus. Consequently, this reduced vesicular glutamate and zinc level resulted in a reduction of reactive oxygen species production after TBI. When evaluated 24hours after TBI, acamprosate administration reduced the number of degenerating neurons, zinc accumulation, blood-brain barrier disruption, neutrophil infiltration, and dendritic loss. Acamprosate also reduced glial activation and neuronal loss at 7days after TBI. In addition, acamprosate rescued TBI-induced neurologic and cognitive dysfunction. The present study demonstrates that acamprosate attenuates TBI-induced brain damage by depletion of vesicular glutamate and zinc levels. Therefore, this study suggests that acamprosate may have high therapeutic potential for prevention of TBI-induced neuronal death.

Alcohol withdrawal syndrome management: Is there anything new?

Patients with alcohol use disorder experience frequently alcohol withdrawal syndrome (AWS), which is a potentially life-threatening condition mainly caused by glutamate overactivity. The aim of therapeutic alcohol withdrawal is the entry into a process of complete and lasting abstinence. Therefore preparing withdrawal is crucial to optimize compliance and efficacy of aftercare. Indeed, performing repeated withdrawal per se without any project of subsequent abstinence may be deleterious, at least because of repeated exposure to glutamate neurotoxicity. Managing AWS mainly consists in anticipating severe withdrawal, decreasing the risk of complications, making this experience as comfortable as possible, preventing from long-term benzodiazepine use, and enhancing motivation to aftercare and long-term abstinence. In particular, there are specific guidelines to choose which benzodiazepine administration approach to adopt (i.e. symptom-triggered, fixed schedule or loading dosage) and which other drugs to deliver (e.g. thiamine, folate, magnesium). Specific precautions should be taken in the elderly.

Clinical trials in autism spectrum disorder: evidence, challenges and future directions

PURPOSE OF REVIEW

The purpose of this manuscript is to review the evidence generated by clinical trials of pharmaceuticals in autism spectrum disorder (ASD), describe challenges in the conduct of such trials, and discuss future directions RECENT FINDINGS: Clinical trials in ASD have produced several compounds to adequately support the pharmacological treatment of associated symptom domains: attention deficit hyperactivity disorder (methylphenidate, atomoxetine, and alpha agonists), irritability/aggression (risperidone and aripiprazole), sleep (melatonin), and weight gain associated with atypical antipsychotic use (metformin). However, there is no evidence yet to support the routine use of pharmaceuticals for the treatment of core symptom domains. Challenges in the field include biological heterogeneity within ASD, lack of biomarkers that clarify biological heterogeneity or predict response to treatment, lack of data across the lifespan, and suboptimal outcome measures.

SUMMARY

Several compounds have evidence for the treatment of co-occurring symptoms in children and youth with ASD, although pharmacological interventions for core symptoms are still lacking. Identifying the various biologies underling ASD and developing biomarkers that stratify biologically homogeneous populations are both necessary to realize the promise of precision medicine in ASD.

New Targeted Treatments for Fragile X Syndrome

Fragile X Syndrome (FXS) is the most common cause of inherited intellectual disability with prevalence rates estimated to be 1:5,000 in males and 1:8,000 in females. The increase of >200 Cytosine Guanine Guanine (CGG) repeats in the 5' untranslated region of the Fragile X Mental Retardation 1 (FMR1) gene results in transcriptional silencing on the FMR1 gene with a subsequent reduction or absence of fragile X mental retardation protein (FMRP), an RNA binding protein involved in the maturation and elimination of synapses. In addition to intellectual disability, common features of FXS are behavioral problems, autism, language deficits and atypical physical features. There are still no currently approved curative therapies for FXS, and clinical management continues to focus on symptomatic treatment of comorbid behaviors and psychiatric problems. Here we discuss several treatments that target the neurobiological pathway abnormal in FXS. These medications are clinically available at present and the data suggest that these medications can be helpful for those with FXS.

Acamprosate Protects Against Adjuvant-Induced Arthritis in Rats via Blocking the ERK/MAPK and NF-κB Signaling Pathway

Osteoarthritis is a type of joint disease that results from the breakdown of joint cartilage and underlying bone and is believed to be caused by mechanical stress on the joint and low-grade inflammatory processes. Acamprosate significantly ameliorates the pathological features of experimental autoimmune encephalomyelitis due to its anti-inflammatory effect. The aims of the present study were to investigate the anti-arthritis activities of acamprosate and elucidate the underlying mechanisms. Adjuvant-induced arthritis (AIA) was induced by intradermal injection of complete Freund's adjuvant. Male Wistar rats were randomly divided into five groups: (1) sham control group, (2) AIA group, (3) acamprosate 10 mg/kg (AIA + ACA10), (4) acamprosate 30 mg/kg (AIA + ACA30), and (5) acamprosate 100 mg/kg (AIA + ACA100). Paw swelling and the arthritis index were measured, and the production of IL-1β, IL-6, and TNF-α was detected by ELISA in serum. The expression of inflammation-related molecules, including c-Raf, ERK1/2, and NF-κB, was determined by Western blotting. We found that acamprosate significantly suppressed paw swelling and the arthritis index in AIA rats. Moreover, acamprosate also significantly suppressed the production of TNF-α, IL-1β, and IL-6 in serum, which is elevated by AIA induction. Finally, acamprosate inhibited p-c-Raf and p-ERK1/2 and NF-κB activation after AIA treatment. These results indicate that acamprosate has an anti-inflammatory effect on adjuvant-induced arthritic rats via inhibiting the ERK/MAPK and NF-κB signaling pathways, and acamprosate may serve as a promising novel therapeutic agent for osteoarthritis.

Calcium chloride mimics the effects of acamprosate on cognitive deficits in chronic alcohol-exposed mice

RATIONALE

Acamprosate (calcium-bis N-acetylhomotaurinate) is the leading medication approved for the maintenance of abstinence, shown to reduce craving and relapse in animal models and human alcoholics. Acamprosate can improve executive functions that are impaired by chronic intermittent ethanol (CIE) exposure. Recent work has suggested that acamprosate's effects on relapse prevention are due to its calcium component, which raises the question whether its pro-cognitive effects are similarly mediated by calcium.

OBJECTIVES

This study examined the effects of acamprosate on alcohol-induced behavioral deficits and compared them with the effects of the sodium salt version of N-acetylhomotaurinate or calcium chloride, respectively.

METHODS

We exposed mice to alcohol via three cycles of CIE and measured changes in alcohol consumption in a limited-access paradigm. We then compared the effects of acamprosate and calcium chloride (applied subchronically for 3 days during withdrawal) in a battery of cognitive tasks that have been shown to be affected by chronic alcohol exposure.

RESULTS

CIE-treated animals showed deficits in attentional set-shifting and deficits in novel object recognition. Alcohol-treated animals showed no impairments in social novelty detection and interaction, or delayed spontaneous alternation. Both acamprosate and calcium chloride ameliorated alcohol-induced cognitive deficits to comparable extents. In contrast, the sodium salt version of N-acetylhomotaurinate did not reverse the cognitive deficits.

CONCLUSIONS

These results add evidence to the notion that acamprosate produces its anti-relapse effects through its calcium moiety. Our results also suggest that improved regulation of drug intake by acamprosate after withdrawal might at least in part be related to improved cognitive function.

Drug-drug interactions in the treatment for alcohol use disorders: A comprehensive review

Drug interactions are one of the most common causes of side effects in polypharmacy. Alcoholics are a category of patients at high risk of pharmacological interactions, due to the presence of comorbidities, the concomitant intake of several medications and the pharmacokinetic and pharmacodynamic interferences of ethanol. However, the data available on this issue are limited. These reasons often frighten clinicians when prescribing appropriate pharmacological therapies for alcohol use disorder (AUD), where less than 15% of patients receive an appropriate treatment in the most severe forms. The data available in literature regarding the relevant drug-drug interactions of the medications currently approved in United States and in some European countries for the treatment of AUD (benzodiazepines, acamprosate, baclofen, disulfiram, nalmefene, naltrexone and sodium oxybate) are reviewed here. The class of benzodiazepines and disulfiram are involved in numerous pharmacological interactions, while they are not conspicuous for acamprosate. The other drugs are relatively safe for pharmacological interactions, excluding the opioid withdrawal syndrome caused by the combination of nalmefene or naltrexone with an opiate medication. The information obtained is designed to help clinicians in understanding and managing the pharmacological interactions in AUDs, especially in patients under multi-drug treatment, in order to reduce the risk of a negative interaction and to improve the treatment outcomes.

mGlu5-dependent modulation of anxiety during early withdrawal from binge-drinking in adult and adolescent male mice

Binge alcohol-drinking elicits symptoms of negative affect such as anxiety upon cessation, which is a source of negative reinforcement for perpetuating this pattern of alcohol abuse. Binge-induced anxiety during early (24 h) withdrawal is associated with increased expression of metabotropic glutamate receptor 5 (mGlu5) within the nucleus accumbens shell (AcbSh) of adult male mice, but was unchanged in anxiety-resilient adolescents. Herein, we determined the role of mGlu5 signaling in withdrawal-induced anxiety via pharmacological manipulation using the mGlu5 negative allosteric modulator MTEP and the positive allosteric modulator CDPPB. Adult (PND 56) and adolescent (PND 28) male C57BL/6J mice binge-drank for 14 days under 3-bottle-choice procedures for 2 h/day; control animals drank water only. Approximately 24 h following the final alcohol presentation, animals were treated with 30 mg/kg IP MTEP, CDPPB, or vehicle and then tested, thirty minutes later, for behavioral signs of anxiety. Vehicle-treated binge-drinking adults exhibited hyperanxiety in all paradigms, while vehicle-treated binge-drinking adolescents did not exhibit withdrawal-induced anxiety. In adults, 30 mg/kg MTEP decreased alcohol-induced anxiety across paradigms, while 3 mg/kg MTEP was anxiolytic in adult water controls. CDPPB was modestly anxiogenic in both alcohol- and water-drinking mice. Adolescent animals showed minimal response to either CDPPB or MTEP, suggesting that anxiety in adolescence may be mGlu5-independent. These results demonstrate a causal role for mGlu5 in withdrawal-induced anxiety in adults and suggest age-related differences in the behavioral pharmacology of the negative reinforcing properties of alcohol.

Cognitive effects of labeled addictolytic medications

INTRODUCTION

Alcohol, tobacco, and illegal drug usage is pervasive throughout the world, and abuse of these substances is a major contributor to the global disease burden. Many pharmacotherapies have been developed over the last 50years to target addictive disorders. While the efficacy of these pharmacotherapies is largely recognized, their cognitive impact is less known. However, all substance abuse disorders are known to promote cognitive disorders like executive dysfunction and memory impairment. These impairments are critical for the maintenance of addictive behaviors and impede cognitive behavioral therapies that are regularly administered in association with pharmacotherapies. It is also unknown if addictolytic medications have an impact on preexisting cognitive disorders, and if this impact is modulated by the indication of prescription, i.e. abstinence, reduction or substitution, or by the specific action of the medication.

METHOD

We reviewed the cognitive effects of labeled medications for tobacco addiction (varenicline, bupropion, nicotine patch and nicotine gums), alcohol addiction (naltrexone, nalmefene, baclofen, disulfiram, sodium oxybate, acamprosate), and opioid addiction (methadone, buprenorphine) in human studies. Studies were selected following MOOSE guidelines for systematic reviews of observational studies, using the keywords [Cognition] and [Cognitive disorders] and [treatment] for each medication.

RESULTS

971 articles were screened and 77 studies met the inclusion criteria and were reported in this review (for alcohol abuse, n=21, for tobacco n=22, for opioid n=34. However, very few comparative clinical trials have explored the chronic effects of addictolytic medications on cognition in addictive behaviors, and there are no clinical trials on the cognitive impact of nalmefene in patients suffering from alcohol use disorders.

DISCUSSION

Although some medications seem to enhance cognition in patients suffering from cognitive disorders, others could promote cognitive impairments, and our work highlights a lack of literature on this subject. In conclusion, more comparative clinical trials are needed to better understand the cognitive impact of addictolytic medications.

Drug development for neurodevelopmental disorders: lessons learned from fragile X syndrome

Neurodevelopmental disorders such as fragile X syndrome (FXS) result in lifelong cognitive and behavioural deficits and represent a major public health burden. FXS is the most frequent monogenic form of intellectual disability and autism, and the underlying pathophysiology linked to its causal gene, FMR1, has been the focus of intense research. Key alterations in synaptic function thought to underlie this neurodevelopmental disorder have been characterized and rescued in animal models of FXS using genetic and pharmacological approaches. These robust preclinical findings have led to the implementation of the most comprehensive drug development programme undertaken thus far for a genetically defined neurodevelopmental disorder, including phase IIb trials of metabotropic glutamate receptor 5 (mGluR5) antagonists and a phase III trial of a GABA_B receptor agonist. However, none of the trials has been able to unambiguously demonstrate efficacy, and they have also highlighted the extent of the knowledge gaps in drug development for FXS and other neurodevelopmental disorders. In this Review, we examine potential issues in the previous studies and future directions for preclinical and clinical trials. FXS is at the forefront of efforts to develop drugs for neurodevelopmental disorders, and lessons learned in the process will also be important for such disorders.

Review of Salient Investigational Drugs for the Treatment of Fragile X Syndrome

OBJECTIVES

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability, in addition to being the commonest diagnosable cause of autism. The identification of the biochemical mechanism underlying this disorder has provided amenable targets for therapy. This review aims to provide an overview of investigational drug therapies for FXS.

METHODS

The authors carried out a search of clinical and preclinical trials for FXS in PubMed and on the U.S. National Institutes of Health index of clinical trials ( www.clinicaltrials.gov ). We limited our review to Phase II trials or more preliminary and reviewed the associated publications for these studies, complemented by a review of the literature on PubMed.

RESULTS

The review of the preclinical, Phase I, and Phase II trials of agents with therapeutic potential in FXS revolves around an understanding of the putative pathways in the pathogenesis of FXS. While there is significant overlap between some of these pathways, the agents can be categorized as modulators of the metabotropic glutamate receptor system, GABAergic agents, and miscellaneous modulators affecting other pathways.

CONCLUSION

As trials involving agents targeting different aspects of the molecular biology proceed, common themes have emerged. With the great hope came great disappointment as the initial trials failed to demonstrate sufficient significance. In particular, the differences in outcome between the animal models and humans have highlighted the unique challenges of carrying out trials in these cognitively and behaviorally challenged individuals, as well as a dearth of clinically relevant outcome measures for use in medication trials. However, in reviewing and reframing the studies of the last decade, many important lessons have been learned, which will ultimately have a greater impact on therapeutic research in the field of developmental delay as a whole.

Alcohol addiction - the safety of available approved treatment options

INTRODUCTION

Alcohol Use Disorders (AUD) is a leading cause of mortality and morbidity worldwide. At present disulfiram, naltrexone and acamprosate are approved for the treatment of AUD in U.S. and Europe. Nalmefene is approved in Europe and sodium oxybate is approved in Italy and Austria only. Baclofen received a 'temporary recommendation for use' in France.

AREAS COVERED

The safety of the above mentioned medications on liver, digestive system, kidney function, nervous system, pregnancy and lactation and their possible side effects are described and discussed.

EXPERT OPINION

Mechanism of action and metabolism of these drugs as well as patients' clinical characteristics can affect the safety of treatment. All approved medications are valid tools for the treatment of AUD in patients without advanced liver disease. For some drugs, attention should be paid to patients with renal failure and medications may be used with caution, adjusting the dosage according to kidney function. In patients with AUD and advanced liver disease, at present only baclofen has been formally tested in randomized controlled trials showing its safety in this population.

Reward and relief dimensions of temptation to drink: construct validity and role in predicting differential benefit from acamprosate and naltrexone

Researchers have sought to distinguish between individuals whose alcohol use disorder (AUD) is maintained by drinking to relieve negative affect ('relief drinkers') and those whose AUD is maintained by the rewarding effects of alcohol ('reward drinkers'). As an opioid receptor antagonist, naltrexone may be particularly effective for reward drinkers. Acamprosate, which has been shown to down-regulate the glutamatergic system, may be particularly effective for relief drinkers. This study sought to replicate and extend prior work (PREDICT study; Glöckner-Rist et al. ) by examining dimensions of reward and relief temptation to drink and subtypes of individuals with distinct patterns of reward/relief temptation. We utilized data from two randomized clinical trials for AUD (Project MATCH, n = 1726 and COMBINE study, n = 1383). We also tested whether classes of reward/relief temptation would predict differential response to naltrexone and acamprosate in COMBINE. Results replicated prior work by identifying reward and relief temptation factors, which had excellent reliability and construct validity. Using factor mixture modeling, we identified five distinct classes of reward/relief temptation that replicated across studies. In COMBINE, we found a significant class-by-acamprosate interaction effect. Among those most likely classified in the high relief/moderate reward temptation class, individuals had better drinking outcomes if assigned to acamprosate versus placebo. We did not find a significant class-by-naltrexone interaction effect. Our study questions the orthogonal classification of drinkers into only two types (reward or relief drinkers) and adds to the body of research on moderators of acamprosate, which may inform clinical decision making in the treatment of AUD.

Impact on GABA systems in monogenetic developmental CNS disorders: Clues to symptomatic treatment

Animal studies of several single-gene disorders demonstrate that reversing the molecular signaling deficits can result in substantial symptomatic improvements in function. Focusing on the ratio of excitation to inhibition as a potential pathophysiological hallmark, seven single-gene developmental CNS disorders are reviewed which are characterized by a striking dysregulation of neuronal inhibition. Deficits in inhibition and excessive inhibition are found. The examples of developmental disorders encompass Neurofibromatosis type 1, Fragile X syndrome, Rett syndrome, Dravet syndrome including autism-like behavior, NONO-mutation-induced intellectual disability, Succinic semialdehyde dehydrogenase deficiency and Congenital nystagmus due to FRMD7 mutations. The phenotype/genotype correlations observed in animal models point to potential treatment options and will continue to inspire clinical research. Three drugs are presently in clinical trials: acamprosate and ganoxolon for Fragile X syndrome and SGS-742 for SSADH deficiency. This article is part of the "Special Issue Dedicated to Norman G. Bowery".

Prediction of Novel Drugs for Hepatocellular Carcinoma Based on Multi-Source Random Walk

Computational approaches for predicting drug-disease associations by integrating gene expression and biological network provide great insights to the complex relationships among drugs, targets, disease genes, and diseases at a system level. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with a high rate of morbidity and mortality. We provide an integrative framework to predict novel d rugs for HCC based on multi-source random walk (PD-MRW). Firstly, based on gene expression and protein interaction network, we construct a gene-gene weighted i nteraction network (GWIN). Then, based on multi-source random walk in GWIN, we build a drug-drug similarity network. Finally, based on the known drugs for HCC, we score all drugs in the drug-drug similarity network. The robustness of our predictions, their overlap with those reported in Comparative Toxicogenomics Database (CTD) and literatures, and their enriched KEGG pathway demonstrate our approach can effectively identify new drug indications. Specifically, regorafenib (Rank = 9 in top-20 list) is proven to be effective in Phase I and II clinical trials of HCC, and the Phase III trial is ongoing. And, it has 11 overlapping pathways with HCC with lower p-values. Focusing on a particular disease, we believe our approach is more accurate and possesses better scalability.

Fragile X targeted pharmacotherapy: lessons learned and future directions

Our understanding of fragile X syndrome (FXS) pathophysiology continues to improve and numerous potential drug targets have been identified. Yet, current prescribing practices are only symptom-based in order to manage difficult behaviors, as no drug to date is approved for the treatment of FXS. Drugs impacting a diversity of targets in the brain have been studied in recent FXS-specific clinical trials. While many drugs have focused on regulation of enhanced glutamatergic or deficient GABAergic neurotransmission, compounds studied have not been limited to these mechanisms. As a single-gene disorder, it was thought that FXS would have consistent drug targets that could be modulated with pharmacotherapy and lead to significant improvement. Unfortunately, despite promising results in FXS animal models, translational drug treatment development in FXS has largely failed. Future success in this field will depend on learning from past challenges to improve clinical trial design, choose appropriate outcome measures and age range choices, and find readily modulated drug targets. Even with many negative placebo-controlled study results, the field continues to move forward exploring both the new mechanistic drug approaches combined with ways to improve trial execution. This review summarizes the known phenotype and pathophysiology of FXS and past clinical trial rationale and results, and discusses current challenges facing the field and lessons from which to learn for future treatment development efforts.

Molecular fingerprinting of principal neurons in the rodent hippocampus: A neuroinformatics approach

Neurons are often classified by their morphological and molecular properties. The online knowledge base Hippocampome.org primarily defines neuron types from the rodent hippocampal formation based on their main neurotransmitter (glutamate or GABA) and the spatial distributions of their axons and dendrites. For each neuron type, this open-access resource reports any and all published information regarding the presence or absence of known molecular markers, including calcium-binding proteins, neuropeptides, receptors, channels, transcription factors, and other molecules of biomedical relevance. The resulting chemical profile is relatively sparse: even for the best studied neuron types, the expression or lack thereof of fewer than 70 molecules has been firmly established to date. The mouse genome-wide in situ hybridization mapping of the Allen Brain Atlas provides a wealth of data that, when appropriately analyzed, can substantially augment the molecular marker knowledge in Hippocampome.org. Here we focus on the principal cell layers of dentate gyrus (DG), CA3, CA2, and CA1, which together contain approximately 90% of hippocampal neurons. These four anatomical parcels are densely packed with somata of mostly excitatory projection neurons. Thus, gene expression data for those layers can be justifiably linked to the respective principal neuron types: granule cells in DG and pyramidal cells in CA3, CA2, and CA1. In order to enable consistent interpretation across genes and regions, we screened the whole-genome dataset against known molecular markers of those neuron types. The resulting threshold values allow over 6000 very-high confidence (>99.5%) expressed/not-expressed assignments, expanding the biochemical information content of Hippocampome.org more than five-fold. Many of these newly identified molecular markers are potential pharmacological targets for major neurological and psychiatric conditions. Furthermore, our approach yields reasonable expression/non-expression estimates for every single gene in each of these four neuron types with >90% average confidence, providing a considerably complete genetic characterization of hippocampal principal neurons.

Pharmacotherapy for Fragile X Syndrome: Progress to Date

To date, no drug is approved for the treatment of Fragile X Syndrome (FXS) although many drugs are used to manage challenging behaviors from a symptomatic perspective in this population. While our understanding of FXS pathophysiology is expanding, efforts to devise targeted FXS-specific treatments have had limited success in placebo-controlled trials. Compounds aimed at rectifying excessive glutamate and deficient gamma-aminobutyric acid (GABA) neurotransmission, as well as other signaling pathways known to be affected by Fragile X Mental Retardation Protein (FMRP) are under various phases of development in FXS. With the failure of several metabotropic glutamate receptor subtype 5 (mGlur5) selective antagonists under clinical investigation, no clear single treatment appears to be greatly effective. These recent challenges call into question various aspects of clinical study design in FXS. More objective outcome measures are under development and validation. Future trials will likely be aimed at correcting multiple pathways known to be disrupted by the loss of FMRP. This review offers a brief summary of the prevalence, phenotypic characteristics, genetic causes and molecular functions of FMRP in the brain (as these have been extensively reviewed elsewhere), discusses the most recent finding in FXS drug development, and summarizes FXS trials utilizing symptomatic treatment.

From genetic studies to precision medicine in alcohol dependence

Genetic factors contribute to more than 50% of the variation in the vulnerability to alcohol dependence (AD). Although significant advances have been made in medications for AD, these medications do not work for all people. Precise tailoring of medicinal strategies for individual alcoholic patients is needed to achieve optimal outcomes. This review updates the most promising information on genetic variants in AD, which may be useful for improving diagnostic, therapeutic, and monitoring strategies. We describe genetic candidates of various neurotransmitter and enzyme systems. In addition to biological and allelic associations with AD, genetic effects on AD-related phenotypes and treatment responses have also been described. Gene-gene and gene-environment interactions have been considered. Potential applications of genomewide and epigenetic approaches for identifying genetic biomarkers of AD have been discussed. Overall, the application of genetic findings in precision medicine for AD will likely involve an integrated approach that distinguishes effect sizes of specific genetic predictors with regard to sex, pharmacotherapy, ethnicity, and AD-related aspects and considers gene-gene and gene-environment interactions. Our work may pave the way toward more precise treatment for AD that could ultimately improve clinical management and interventions.

Advances in the Understanding of the Gabaergic Neurobiology of FMR1 Expanded Alleles Leading to Targeted Treatments for Fragile X Spectrum Disorder

Fragile X spectrum disorder (FXSD) includes: fragile X syndrome (FXS), fragile X-associated tremor ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI), as well as other medical, psychiatric and neurobehavioral problems associated with the premutation and gray zone alleles. FXS is the most common monogenetic cause of autism (ASD) and intellectual disability (ID). The understanding of the neurobiology of FXS has led to many targeted treatment trials in FXS. The first wave of phase II clinical trials in FXS were designed to target the mGluR5 pathway; however the results did not show significant efficacy and the trials were terminated. The advances in the understanding of the GABA system in FXS have shifted the focus of treatment trials to GABA agonists, and a new wave of promising clinical trials is under way. Ganaxolone and allopregnanolone (GABA agonists) have been studied in individuals with FXSD and are currently in phase II trials. Both allopregnanolone and ganaxolone may be efficacious in treatment of FXS and FXTAS, respectively. Allopregnanolone, ganaxolone, riluzole, gaboxadol, tiagabine, and vigabatrin are potential GABAergic treatments. The lessons learned from the initial trials have not only shifted the targeted system, but also have refined the design of clinical trials. The results of these new trials will likely impact further clinical trials for FXS and other genetic disorders associated with ASD.

Alcohol use dependence in fragile X syndrome

Alcohol use disorders (AUDs) have been reported in a limited number of individuals with cognitive impairment but rarely in those with fragile X syndrome (FXS). However, in Colombia, culturally, alcohol consumption is very common. Here, we report eight cases of patients with FXS who have frequent alcohol consumption in Ricaurte, Colombia. Some of these patients have also used tobacco and illegal substances, including cocaine, which use has not been previously reported in those with FXS. Alcohol and substance use dependence is associated with exacerbation of their behavioral problems, such as increased impulsivity and aggression, as well as of medical problems such as an increased frequency of seizures.

Acamprosate: A Review of Its Use in Alcohol Dependence

Acamprosate (Campral(®), Aotal(®), Regtect(®)) is one of a limited number of pharmacological treatment options approved as an adjunct to psychosocial interventions to facilitate the maintenance of abstinence in alcohol-dependent patients. It has been used in Europe, the USA and other countries for many years and was recently approved for this indication in Japan. In several randomized, double-blind, placebo-controlled trials (without active comparators), acamprosate in conjunction with psychosocial therapy for 3-12 months was generally significantly better than placebo plus psychosocial interventions in improving various key outcomes, including the proportion of patients who maintained complete abstinence from alcohol (complete abstinence rate), the mean cumulative abstinence duration, the percentage of alcohol-free days and the median time to first drink. Acamprosate as an adjunct to psychosocial interventions also demonstrated efficacy in some randomized, active-comparator trials of similar duration. Although results were not always consistent across individual trials, overall findings were generally favourable for acamprosate in a recent meta-analysis, which showed that alcohol-consumption outcomes were similarly improved with acamprosate or naltrexone. Acamprosate is generally well tolerated, has a low propensity for drug interactions and may be used without dosage adjustment in patients with mild to moderate hepatic impairment, although dosage adjustments or contraindications are recommended in patients with renal impairment. Thus, the use of acamprosate as an adjunct to psychosocial interventions in alcohol-dependent patients provides modest but potentially valuable improvements in alcohol-consumption outcomes and is generally well tolerated.

Glutamatergic transmission in drug reward: implications for drug addiction

Individuals addicted to drugs of abuse such as alcohol, nicotine, cocaine, and heroin are a significant burden on healthcare systems all over the world. The positive reinforcing (rewarding) effects of the above mentioned drugs play a major role in the initiation and maintenance of the drug-taking habit. Thus, understanding the neurochemical mechanisms underlying the reinforcing effects of drugs of abuse is critical to reducing the burden of drug addiction in society. Over the last two decades, there has been an increasing focus on the role of the excitatory neurotransmitter glutamate in drug addiction. In this review, pharmacological and genetic evidence supporting the role of glutamate in mediating the rewarding effects of the above described drugs of abuse will be discussed. Further, the review will discuss the role of glutamate transmission in two complex heterogeneous brain regions, namely the nucleus accumbens (NAcc) and the ventral tegmental area (VTA), which mediate the rewarding effects of drugs of abuse. In addition, several medications approved by the Food and Drug Administration that act by blocking glutamate transmission will be discussed in the context of drug reward. Finally, this review will discuss future studies needed to address currently unanswered gaps in knowledge, which will further elucidate the role of glutamate in the rewarding effects of drugs of abuse.

Glutamatergic transmission in the central nucleus of the amygdala is selectively altered in Marchigian Sardinian alcohol-preferring rats: Alcohol and CRF effects

The CRF system of the central nucleus of the amygdala (CeA) is important for the processing of anxiety, stress, and effects of acute and chronic ethanol. We previously reported that ethanol decreases evoked glutamate transmission in the CeA of Sprague Dawley rats and that ethanol dependence alters glutamate release in the CeA. Here, we examined the effects of ethanol, CRF and a CRF1 receptor antagonist on spontaneous and evoked glutamatergic transmission in CeA neurons from Wistar and Marchigian Sardinian Preferring (msP) rats, a rodent line genetically selected for excessive alcohol drinking and characterized by heightened activity of the CRF1 system. Basal spontaneous and evoked glutamate transmission in CeA neurons from msP rats was increased compared to Wistar rats. Ethanol had divergent effects, either increasing or decreasing spontaneous glutamate release in the CeA of Wistar rats. This bidirectional effect was retained in msP rats, but the magnitude of the ethanol-induced increase in glutamate release was significantly smaller. The inhibitory effect of ethanol on evoked glutamatergic transmission was similar in both strains. CRF also either increased or decreased spontaneous glutamate release in CeA neurons of Wistar rats, however, in msP rats CRF only increased glutamate release. The inhibitory effect of CRF on evoked glutamatergic transmission was also lost in neurons from msP rats. A CRF1 antagonist produced only minor effects on spontaneous glutamate transmission, which were consistent across strains, and no effects on evoked glutamate transmission. These results demonstrate that the genetically altered CRF system of msP rats results in alterations in spontaneous and stimulated glutamate signaling in the CeA that may contribute to both the anxiety and drinking behavioral phenotypes.

An analysis of moderators in the COMBINE study: Identifying subgroups of patients who benefit from acamprosate

The goal of the current study was to use tree-based methods to identify moderators of acamprosate effect on abstinence from heavy drinking in COMBINE, the largest study of pharmacotherapy for alcoholism in the United States to date. We used three different tree-based methods for identification of subgroups with enhanced treatment response on acamprosate based on over 100 predictors measured at baseline in COMBINE. No heavy drinking during the last two months of treatment was the considered outcome. All three methods identified consecutive days of abstinence prior to treatment as the most important moderator of treatment effect. Acamprosate was beneficial for participants with shorter abstinence (1 week or less) especially when body mass index was low or normal. In this group, 46% of participants receiving active acamprosate abstained from heavy drinking compared to 23% of those receiving placebo acamprosate. Prior treatment, age, drinking goal and cognitive inefficiency were identified as moderators of acamprosate effects by one of the three methods. In conclusion, acamprosate may be beneficial for participants with shorter abstinence who are not overweight or obese. One hypothesis for this finding is that this subgroup may have greater glutamatergic hyperactivity, a target of acamprosate, and may achieve better drug plasma levels based on their lower BMI. In contrast, those with extended pretreatment abstinence who have an otherwise good prognosis did not benefit from acamprosate. Further validation of the results in independent data sets is necessary.

Alcohol liver disease: A review of current therapeutic approaches to achieve long-term abstinence

Harmful alcohol drinking may lead to significant damage on any organ or system of the body. Alcoholic liver disease (ALD) is the most prevalent cause of advanced liver disease in Europe. In ALD, only alcohol abstinence was associated with a better long-term survival. Therefore, current effective therapeutic strategy should be oriented towards achieving alcohol abstinence or a significant reduction in alcohol consumption. Screening all primary care patients to detect those cases with alcohol abuse has been proposed as population-wide preventive intervention in primary care. It has been suggested that in patients with mild alcohol use disorder the best approach is brief intervention in the primary care setting with the ultimate goal being abstinence, whereas patients with moderate-to-severe alcohol use disorder must be referred to specialized care where detoxification and medical treatment of alcohol dependence must be undertaken.

Glucagon-like peptide-1 (GLP-1) receptor agonist prevents development of tolerance to anti-anxiety effect of ethanol and withdrawal-induced anxiety in rats

Despite major advances in the understanding about ethanol actions, the precise underlying neurobiological mechanisms for ethanol dependence remain largely elusive. We recently reported that inhibition of dipeptidyl-peptidase IV (DPP-IV), an enzyme responsible for metabolism of endogenous glucagon-like peptide-1 (GLP-1), delays tolerance to anti-anxiety effect of ethanol and withdrawal-induced anxiety in rats. Intrigued with this report, present study examined the role of glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide in (1) acute anti-anxiety effect of ethanol; (2) tolerance to ethanol's anti-anxiety-effect and (3) ethanol withdrawal-induced anxiety using elevated plus maze (EPM) test in rats. Ethanol (2 g/kg, i.p.; 8 % w/v) and liraglutide (50 μg/kg, i.p.) treatments exhibited anti-anxiety effect in EPM test. Doses of ethanol (1.0 or 1.5 g/kg, i.p.) that were not effective per se elicited anti-anxiety when combined with sub-effective dose of liraglutide (25 μg/kg, i.p.). Rats consuming ethanol-diet (6 % v/v) exhibited tolerance to anti-anxiety effect of ethanol from day-7 of ethanol consumption. Peak ethanol withdrawal-induced anxiety was observed at 8-10 h upon abstinence from ethanol-diet after 15-days consumption. Rats on simultaneous once-daily liraglutide treatment (50 μg/kg, i.p.) neither had any signs of tolerance to anti-anxiety effect of ethanol nor did they exhibit withdrawal-induced anxiety.

IN CONCLUSION

(1) GLP-1 agonist, liraglutide exhibited anti-anxiety effect per se; (2) potentiated anti-anxiety effect of ethanol; (3) prevented development tolerance to anti-anxiety effect of ethanol and (4) prevented withdrawal-induced anxiety. Further studies examining intracellular cascade of events contributing to these effects may help to improve understanding about role of GLP-1 receptors in ethanol mediated behaviors.

Dipeptidyl-peptidase IV (DPP-IV) inhibitor delays tolerance to anxiolytic effect of ethanol and withdrawal-induced anxiety in rats

Dipeptidyl-peptidase IV (DPP-IV) is an enzyme responsible for the metabolism of endogenous gut-derived hormone, glucagon-like peptide-1 (GLP-1). DPP-IV is known for its role in energy homeostasis and pharmacological blockade of this enzyme is a recently approved clinical strategy for the management of type II diabetes. Accumulating evidences suggest that enzyme DPP-IV can affect spectrum of central nervous system (CNS) functions. However, little is known about the role of this enzyme in ethanol-mediated neurobehavioral complications. The objective of the present study was to examine the impact of DPP-IV inhibitor, sitagliptin on the development of tolerance to anxiolytic effect of ethanol and anxiety associated with ethanol withdrawal in rats. A dose-response study revealed that sitaglitpin (20 mg/kg, p.o.) per se exhibit anxiolytic effect in the elevated plus maze (EPM) test in rats. Tolerance to anxiolytic effect of ethanol (2 g/kg, i.p.; 8 % w/v) was observed from 7(th) day of ethanol-diet (6 % v/v) consumption. In contrast, tolerance to anxiolytic effect of ethanol was delayed in rats that were treated daily with sitagliptin (20 mg/kg, p.o.) as tolerance was observed from 13(th)day since commencement of ethanol-diet consumption. Discontinuation of rats from ethanol-diet after 15-days of ethanol consumption resulted in withdrawal anxiety between 8 h and 12 h post-abstinence. However, rats on 15-day ethanol-diet with concomitant sitagliptin (20 mg/kg, p.o.) treatment exhibited delay in appearance (24 h post-withdrawal) of withdrawal anxiety. In summary, DPP-IV inhibitors may prove as an attractive research strategy against ethanol tolerance and dependence.

Pharmacotherapy for alcohol dependence: A stratified approach

Alcohol dependence is a common disorder in many societies worldwide, and remains difficult to identify and treat. It is also a risk factor for many secondary non-communicable diseases. Pharmacotherapy is one available treatment option, but appears to be underutilised in practice. Major barriers to use of medications in this area include lack of clinical guidance and questionable efficacy. However, for each medication there appears to be a subpopulation that responds positively, and understanding the moderating factors to treatment efficacy is an important research goal. Thus, this review provides a narrative regarding potential stratification techniques in pharmacological treatment of alcohol dependence, with a specific focus on typologies and pharmacogenetics. In addition, we discuss the basic background of stratified medicine and recent studies on genetic predisposition to alcohol dependence. A growing repository of data exists for both approved and non-approved pharmacotherapies, but failure to replicate findings, inadequate sample sizes, and insufficient funding has resulted in a translational gap. Implementing evidence-based stratified/personalised therapy and identifying new therapeutic agents may lead to improved clinical outcomes and reduced financial burden. Despite some promising findings to date, much work is still required.

Emerging pharmacologic treatment options for fragile X syndrome

Fragile X syndrome (FXS) is the most common single gene cause of intellectual disability and autism spectrum disorder. Caused by a silenced fragile X mental retardation 1 gene and the subsequent deficiency in fragile X mental retardation protein, patients with FXS experience a range of physical, behavioral, and intellectual debilitations. The FXS field, as a whole, has recently met with some challenges, as several targeted clinical trials with high expectations of success have failed to elucidate significant improvements in a variety of symptom domains. As new clinical trials in FXS are planned, there has been much discussion about the use of the commonly used clinical outcome measures, as well as study design considerations, patient stratification, and optimal age range for treatment. The evidence that modification of these drug targets and use of these failed compounds would prove to be efficacious in human clinical study were rooted in years of basic and translational research. There are questions arising as to the use of the mouse models for studying FXS treatment development. This issue is twofold: many of the symptom domains and molecular and biochemical changes assessed and indicative of efficacy in mouse model study are not easily amenable to clinical trials in people with FXS because of the intolerability of the testing paradigm or a lack of noninvasive techniques (prepulse inhibition, sensory hypersensitivity, startle reactivity, or electrophysiologic, biochemical, or structural changes in the brain); and capturing subtle yet meaningful changes in symptom domains such as sociability, anxiety, and hyperactivity in human FXS clinical trials is challenging with the currently used measures (typically parent/caregiver rating scales). Clinicians, researchers, and the pharmaceutical industry have all had to take a step back and critically evaluate the way we think about how to best optimize future investigations into pharmacologic FXS treatments. As new clinical trials are coming down the drug discovery pipeline, it is clear that the field is moving in a direction that values the development of molecular biomarkers, less subjective quantitative measures of symptom improvement, and rating scales developed specifically for use in FXS in conjunction with drug safety. While summarizing preclinical evidence, where applicable, and discussing challenges in FXS treatment development, this review details both completed clinical trials for the targeted and symptomatic treatment of FXS and introduces novel projects on the cusp of clinical trial investigation.

Long-term drug treatment of patients with alcohol dependence

Drug therapy for alcohol dependence should only be used in conjunction with a comprehensive treatment plan. Naltrexone and acamprosate have well established efficacy and are first-line treatments. Naltrexone is recommended for patients aiming to cut down their alcohol intake who do not have severe liver disease or an ongoing need for opioids. Acamprosate is recommended for those who have achieved and wish to maintain abstinence. Disulfiram is no longer considered first-line treatment due to difficulties with compliance and toxicity. Although baclofen and topiramate have evidence of benefit, they are not registered for alcohol dependence and should only be considered in specialist practice.

[³H]Ifenprodil binding in post-mortem brains of Cloninger type 1 and 2 alcoholics: a whole-hemisphere autoradiography study

The glutamate N-methyl-d-aspartate (NMDA) receptor NR2B subunits are sensitive to ethanol and are found in brain areas related to ethanol addiction, dependence, development of alcohol tolerance, and alcohol withdrawal syndrome. Previous studies indicate that early-onset Cloninger type 2 alcoholics have an intact, responsive, dopaminergic system in the nucleus accumbens (NAC), whereas type 1 alcoholics have dopaminergic defects. NR2B-containing NMDA receptors in the NAC are involved in both non-opioid and opioid receptor-mediated reward. Our aim was to evaluate the putative [(3)H]ifenprodil binding alterations of NR2B receptors in limbic, hippocampal, and cortical brain areas of type 1 alcoholics (n=8), type 2 alcoholics (n=8), and control subjects (n=10) by postmortem whole hemisphere autoradiography. We found significantly different binding levels among these three subject groups, and the main difference was localized in the decreased binding in type 2 alcoholics and controls in the nucleus accumbens. Although preliminary and from relatively small diagnostic groups, these results suggest pathological alterations in the NR2B-mediated reward system of type 2 alcoholics.