Reported Risky Alcohol Use Among US Adults Prescribed 3 Classes of Chronic Alcohol-Interactive Medications

This study uses data from the 2013–March 2020 National Health and Nutrition Examination Survey to assess contemporary patterns of risky alcohol use among adults taking high-risk alcohol-interactive medications (benzodiazepine receptor agonists, opioids, and antiepileptics).

Repurposing disulfiram, an alcohol-abuse drug, in neuroblastoma causes KAT2A downregulation and in vivo activity with a water/oil emulsion

Neuroblastoma, the most common type of pediatric extracranial solid tumor, causes 10% of childhood cancer deaths. Despite intensive multimodal treatment, the outcomes of high-risk neuroblastoma remain poor. We urgently need to develop new therapies with safe long-term toxicity profiles for rapid testing in clinical trials. Drug repurposing is a promising approach to meet these needs. Here, we investigated disulfiram, a safe and successful chronic alcoholism treatment with known anticancer and epigenetic effects. Disulfiram efficiently induced cell cycle arrest and decreased the viability of six human neuroblastoma cell lines at half-maximal inhibitory concentrations up to 20 times lower than its peak clinical plasma level in patients treated for chronic alcoholism. Disulfiram shifted neuroblastoma transcriptome, decreasing MYCN levels and activating neuronal differentiation. Consistently, disulfiram significantly reduced the protein level of lysine acetyltransferase 2A (KAT2A), drastically reducing acetylation of its target residues on histone H3. To investigate disulfiram's anticancer effects in an in vivo model of high-risk neuroblastoma, we developed a disulfiram-loaded emulsion to deliver the highly liposoluble drug. Treatment with the emulsion significantly delayed neuroblastoma progression in mice. These results identify KAT2A as a novel target of disulfiram, which directly impacts neuroblastoma epigenetics and is a promising candidate for repurposing to treat pediatric neuroblastoma.

Integration of a physiologically-based pharmacokinetic model with a whole-body, organ-resolved genome-scale model for characterization of ethanol and acetaldehyde metabolism

Ethanol is one of the most widely used recreational substances in the world and due to its ubiquitous use, ethanol abuse has been the cause of over 3.3 million deaths each year. In addition to its effects, ethanol's primary metabolite, acetaldehyde, is a carcinogen that can cause symptoms of facial flushing, headaches, and nausea. How strongly ethanol or acetaldehyde affects an individual depends highly on the genetic polymorphisms of certain genes. In particular, the genetic polymorphisms of mitochondrial aldehyde dehydrogenase, ALDH2, play a large role in the metabolism of acetaldehyde. Thus, it is important to characterize how genetic variations can lead to different exposures and responses to ethanol and acetaldehyde. While the pharmacokinetics of ethanol metabolism through alcohol dehydrogenase have been thoroughly explored in previous studies, in this paper, we combined a base physiologically-based pharmacokinetic (PBPK) model with a whole-body genome-scale model (WBM) to gain further insight into the effect of other less explored processes and genetic variations on ethanol metabolism. This combined model was fit to clinical data and used to show the effect of alcohol concentrations, organ damage, ALDH2 enzyme polymorphisms, and ALDH2-inhibiting drug disulfiram on ethanol and acetaldehyde exposure. Through estimating the reaction rates of auxiliary processes with dynamic Flux Balance Analysis, The PBPK-WBM was able to navigate around a lack of kinetic constants traditionally associated with PK modelling and demonstrate the compensatory effects of the body in response to decreased liver enzyme expression. Additionally, the model demonstrated that acetaldehyde exposure increased with higher dosages of disulfiram and decreased ALDH2 efficiency, and that moderate consumption rates of ethanol could lead to unexpected accumulations in acetaldehyde. This modelling framework combines the comprehensive steady-state analyses from genome-scale models with the dynamics of traditional PK models to create a highly personalized form of PBPK modelling that can push the boundaries of precision medicine.

Comparison of Disulfiram and Naltrexone in Cases of Alcohol Dependence Syndrome

BACKGROUND

Relapse prevention in alcoholism is recognised as an important component of management. Use of pharmacotherapies to prevent relapse in combination to psychological intervention is emerging. Disulfiram and Naltrexone are two of three FDA approved drugs for pharmacotherapy. The aim of the study is to compare the effectiveness of these two drugs in preventing relapse in alcohol dependence syndrome cases.

METHODS

A prospective crossectional study was conducted to compare disulfiram and naltrexone in alcohol dependent patients in tertiary institution. Cases of alcohol dependence syndrome were diagnosed based on ICD-10 DCR presenting to psychiatry department of Tribhuvan University Teaching Hospital, over the period of 6 months. After detoxification and fulfillment of inclusion criteria, semi structured proforma, Severity of alcohol dependence questionnaire, Stages of change readiness and treatment eagerness scale, Obsessive compulsive drinking scale were applied. Drug allocation was based on simple random method and on subsequent follow ups done at 2nd, 4th, 8th, 12th week semi structured proforma, Obsessive Compulsive Drinking Scale were completed and psychological intervention continued. After data collection, analysis and final results were computed.

RESULTS

Both drugs reduced craving and amount of alcohol intake(p less than 0.001). Relapse was more in naltrexone group but was not statistically significant (p>0.05). Side effects were more with disulfiram(p less than 0.001) whereas dropout was more in naltrexone group,(p less than 0.01).

CONCLUSIONS

Disulfiram and Naltrexone were equally effective in reducing craving, reducing amount of alcohol intake, and preventing relapse in 12 weeks follow up period. Naltrexone was found to be better in tolerability whereas disulfiram was better in terms of dropout from treatment.

Targeting the NPL4 Adaptor of p97/VCP Segregase by Disulfiram as an Emerging Cancer Vulnerability Evokes Replication Stress and DNA Damage while Silencing the ATR Pathway

Research on repurposing the old alcohol-aversion drug disulfiram (DSF) for cancer treatment has identified inhibition of NPL4, an adaptor of the p97/VCP segregase essential for turnover of proteins involved in multiple pathways, as an unsuspected cancer cell vulnerability. While we reported that NPL4 is targeted by the anticancer metabolite of DSF, the bis-diethyldithiocarbamate-copper complex (CuET), the exact, apparently multifaceted mechanism(s) through which the CuET-induced aggregation of NPL4 kills cancer cells remains to be fully elucidated. Given the pronounced sensitivity to CuET in tumor cell lines lacking the genome integrity caretaker proteins BRCA1 and BRCA2, here we investigated the impact of NPL4 targeting by CuET on DNA replication dynamics and DNA damage response pathways in human cancer cell models. Our results show that CuET treatment interferes with DNA replication, slows down replication fork progression and causes accumulation of single-stranded DNA (ssDNA). Such a replication stress (RS) scenario is associated with DNA damage, preferentially in the S phase, and activates the homologous recombination (HR) DNA repair pathway. At the same time, we find that cellular responses to the CuET-triggered RS are seriously impaired due to concomitant malfunction of the ATRIP-ATR-CHK1 signaling pathway that reflects an unorthodox checkpoint silencing mode through ATR (Ataxia telangiectasia and Rad3 related) kinase sequestration within the CuET-evoked NPL4 protein aggregates.

Naltrexone differentially modulates the neural correlates of motor impulse control in abstinent alcohol-dependent and polysubstance-dependent individuals

Identifying key neural substrates in addiction disorders for targeted drug development remains a major challenge for clinical neuroscience. One emerging target is the opioid system, where substance-dependent populations demonstrate prefrontal opioid dysregulation that predicts impulsivity and relapse. This may suggest that disturbances to the prefrontal opioid system could confer a risk for relapse in addiction due to weakened 'top-down' control over impulsive behaviour. Naltrexone is currently licensed for alcohol dependence and is also used clinically for impulse control disorders. Using a go/no-go (GNG) task, we examined the effects of acute naltrexone on the neural correlates of successful motor impulse control in abstinent alcoholics (AUD), abstinent polysubstance-dependent (poly-SUD) individuals and controls during a randomised double blind placebo controlled fMRI study. In the absence of any differences on GNG task performance, the AUD group showed a significantly greater BOLD response compared to the control group in lateral and medial prefrontal regions during both placebo and naltrexone treatments; effects that were positively correlated with alcohol abstinence. There was also a dissociation in the positive modulating effects of naltrexone in the orbitofrontal cortex (OFC) and anterior insula cortex (AIC) of the AUD and poly-SUD groups respectively. Self-reported trait impulsivity in the poly-SUD group also predicted the effect of naltrexone in the AIC. These results suggest that acute naltrexone differentially amplifies neural responses within two distinct regions of a salience network during successful motor impulse control in abstinent AUD and poly-SUD groups, which are predicted by trait impulsivity in the poly-SUD group.

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.

Genome-Wide Expression Profiles Drive Discovery of Novel Compounds that Reduce Binge Drinking in Mice

Transcriptome-based drug discovery has identified new treatments for some complex diseases, but has not been applied to alcohol use disorder (AUD) or other psychiatric diseases, where there is a critical need for improved pharmacotherapies. High Drinking in the Dark (HDID-1) mice are a genetic model of AUD risk that have been selectively bred (from the HS/Npt line) to achieve intoxicating blood alcohol levels (BALs) after binge-like drinking. We compared brain gene expression of HDID-1 and HS/Npt mice, to determine a molecular signature for genetic risk for high intensity, binge-like drinking. Using multiple computational methods, we queried LINCS-L1000 (Library of Integrated Network-Based Cellular Signatures), a database containing gene expression signatures of thousands of compounds, to predict candidate drugs with the greatest potential to decrease alcohol consumption. Our analyses predicted novel compounds for testing, many with anti-inflammatory properties, providing further support for a neuroimmune mechanism of excessive alcohol drinking. We validated the top 2 candidates in vivo as a proof-of-concept. Terreic acid (a Bruton's tyrosine kinase inhibitor) and pergolide (a dopamine and serotonin receptor agonist) robustly reduced alcohol intake and BALs in HDID-1 mice, providing the first evidence for transcriptome-based drug discovery to target an addiction trait. Effective drug treatments for many psychiatric diseases are lacking, and the emerging tools and approaches outlined here offer researchers studying complex diseases renewed opportunities to discover new or repurpose existing compounds and expedite treatment options.

Pharmacogenetic Effects of Naltrexone in Individuals of East Asian Descent: Human Laboratory Findings from a Randomized Trial

BACKGROUND

Genetic variation in the endogenous opioid system has been identified as 1 potential source of individual variability in naltrexone treatment outcomes. The majority of naltrexone pharmacogenetic studies have focused on a particular single nucleotide polymorphism (SNP) of the mu-opioid receptor gene (OPRM1; rs1799971; commonly known as the Asn40Asp SNP) in Caucasian samples with decidedly mixed results. The goal of this study was to test the pharmacogenetic effects of naltrexone on subjective response to alcohol and self-administration of alcohol in individuals of East Asian descent. We hypothesized that naltrexone, compared with placebo, would potentiate the aversive and sedative effects of alcohol and reduce alcohol self-administration to a greater extent in Asp40 carriers.

METHODS

Participants (N = 77; Asn40Asn, n = 29; Asn40Asp, n = 34, and Asp40Asp, n = 14) completed 2 double-blinded and counterbalanced experimental sessions: one after taking naltrexone (50 mg/d) for 5 days and one after taking matched placebo for 5 days. In each experimental session, participants received a priming dose of intravenous alcohol up to the breath alcohol concentration target of 0.06 g/dl which was immediately followed by an alcohol self-administration period (1 hour).

RESULTS

There were no pharmacogenetic effects observed for alcohol-induced stimulation, sedation, craving for alcohol, or alcohol self-administration in the laboratory. During the self-administration period, Asp40 carriers consumed fewer drinks and had a longer latency to first drink as compared to Asn40 homozygotes.

CONCLUSIONS

These findings in East Asians add to the mixed literature on naltrexone pharmacogenetics from predominantly Caucasian samples and highlight the complexity of these effects and their overall limited replicability. It is plausible that a consistent pharmacogenetic effect in tightly controlled preclinical and experimental medicine models "fades" in more complex and heterogeneous settings and samples.

Are Alcohol Anti-relapsing and Alcohol Withdrawal Drugs Useful in Cannabinoid Users?

Cannabinoids are still classified as illegal psychoactive drugs despite their broad and increasingly acknowledged therapeutic potential. These substances are most famous for their wide recreational use, particularly among young adults to either alter the state of consciousness, intensify pleasure induced by other psychoactive substances or as an alternative to the previously abused drugs. It is important to emphasize that cannabinoids are often taken together with a variety of medications intended for the treatment of alcohol use disorder (AUD) or alcohol withdrawal syndrome (AWS). These medications include disulfiram, acamprosate, and naltrexone. In this paper, we summarize recent advances in the knowledge of possible beneficial effects and interactions between cannabinoids and drugs commonly used for treatment of AUD and AWS either comorbid or existing as a separate disorder.

Alcohol addiction and the mu-opioid receptor

Alcohol addiction is one of the most common and devastating diseases in the world. Given the tremendous heterogeneity of alcohol addicted individuals, it is unlikely that one medication will help nearly all patients. Thus, there is a clear need to develop predictors of response to existing medications. Naltrexone is a mu-opioid receptor antagonist which has been approved in the United States for treatment of alcohol addiction since 1994. It has limited efficacy, in part due to noncompliance, but many patients do not respond despite high levels of compliance. There are reports that a mis-sense single nucleotide polymorphism (rs179919 or A118G) in the mu-opioid receptor gene predicts a favorable response to naltrexone if an individual carries a 'G' allele. This chapter will review the evidence for this hypothesis. The data are promising that the 'G' allele predisposes to a beneficial naltrexone response among alcohol addicted persons, but additional research is needed to prove this hypothesis in prospective clinical trials.

Critical needs in drug discovery for cessation of alcohol and nicotine polysubstance abuse

Polysubstance abuse of alcohol and nicotine has been overlooked in our understanding of the neurobiology of addiction and especially in the development of novel therapeutics for its treatment. Estimates show that as many as 92% of people with alcohol use disorders also smoke tobacco. The health risks associated with both excessive alcohol consumption and tobacco smoking create an urgent biomedical need for the discovery of effective cessation treatments, as opposed to current approaches that attempt to independently treat each abused agent. The lack of treatment approaches for alcohol and nicotine abuse/dependence mirrors a similar lack of research in the neurobiology of polysubstance abuse. This review discusses three critical needs in medications development for alcohol and nicotine co-abuse: (1) the need for a better understanding of the clinical condition (i.e. alcohol and nicotine polysubstance abuse), (2) the need to better understand how these drugs interact in order to identify new targets for therapeutic development and (3) the need for animal models that better mimic this human condition. Current and emerging treatments available for the cessation of each drug and their mechanisms of action are discussed within this context followed by what is known about the pharmacological interactions of alcohol and nicotine. Much has been and will continue to be gained from studying comorbid alcohol and nicotine exposure.

Disulfiram inhibits TGF-β-induced epithelial-mesenchymal transition and stem-like features in breast cancer via ERK/NF-κB/Snail pathway

Disulfiram (DSF), an anti-alcoholism drug, has been reported as an inhibitor of NF-κB. NF-κB is involved in epithelial-mesenchymal transition (EMT) and self-renewal of breast cancer stem cells (CSCs). In this study, we treated MCF-7 and MDA-MB-231 breast cancer cells with TGF-β to induce EMT and cancer stem-like features and studied whether DSF can reverse this process. We found that DSF inhibited TGF-β induced EMT in breast cancer cells in a dose-dependent manner. Also, DSF inhibited EMT-associated stem-like features, migration and invasion of tumor cells as well as tumor growth in xenograft model. The activation of NF-κB was linked with EMT and stem-like cells. We conclude that DSF can suppress NF-κB activity and downregulate ERK/NF-κB/Snail pathway, leading to reverse EMT and stem-like features. Our data suggest that DSF inhibits EMT and stem-like properties in breast cancer cells associated with inhibition of the ERK/NF-κB/Snail pathway.

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.

Amoxicillin and amoxicillin/clavulanate reduce ethanol intake and increase GLT-1 expression as well as AKT phosphorylation in mesocorticolimbic regions

Studies have shown that administration of the β-lactam antibiotic ceftriaxone (CEF) attenuates ethanol consumption and cocaine seeking behavior as well as prevents ethanol-induced downregulation of glutamate transporter 1 (GLT-1) expression in central reward brain regions. However, it is not known if these effects are compound-specific. Therefore, the present study examined the effects of two other β-lactam antibiotics, amoxicillin (AMOX) and amoxicillin/clavulanate (Augmentin, AUG), on ethanol drinking, as well as GLT-1 and phosphorylated-AKT (pAKT) levels in the nucleus accumbens (Acb) and medial prefrontal cortex (mPFC) of alcohol-preferring (P) rats. P rats were exposed to free-choice of ethanol (15% and 30%) for five weeks and were given five consecutive daily i.p. injections of saline vehicle, 100 mg/kg AMOX or 100mg/kg AUG. Both compounds significantly decreased ethanol intake and significantly increased GLT-1 expression in the Acb. AUG also increased GLT-1 expression in the mPFC. Results for changes in pAKT levels matched those for GLT-1, indicating that β-lactam antibiotic-induced reductions in ethanol intake are negatively associated with increases in GLT-1 and pAKT levels within two critical brains regions mediating drug reward and reinforcement. These findings add to a growing literature that pharmacological increases in GLT-1 expression are associated with decreases in ethanol intake and suggest that one mechanism mediating this effect may be increased phosphorylation of AKT. Thus, GLT-1 and pAKT may serve as molecular targets for the treatment of alcohol and drug abuse/dependence.

DIFFERENT RESPONSE OF ANTIOXIDANT DEFENSE SYSTEM TO ACAMPROSATE IN ETHANOL PREFERRING AND NON-PREFERRING RATS

The aim of the study was to investigate whether acamprosate, an agent attenuating relapse in human alcoholics, might modulate antioxidant status in rats chronically administered ethanol. Male Wistar rats were presented with a free choice paradigm between tap water and ethanol solution for three month to distinguish two groups of animals, preferring (PRF) and non-preferring (NPF) ethanol. Then, rats were administered acamprosate, 500 mg/kg/day, per os, for 21 days. The hepatic level of enzymatically-driven lipid peroxidation was enhanced by ethanol in PRF and NPF rats by 67 and 82%, respectively. Unstimulated microsomal lipid peroxidation was increased solely in NPF rats by 33%. Acamprosate caused 36% increase in stimulated lipid peroxidation only in NPF animals. The activities of all hepatic antioxidant enzymes examined: superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase were decreased in rats treated with ethanol by 30 to 64% as compared to controls, however, this decrease was more distinct in ethanol preferring rats. Administration of acamprosate further reduced the activity of antioxidant enzymes only in NPF rats: catalase by 47%, glutathione peroxidase and glutathione S-transferase by 37% and glutathione reductase by 33%. No effect of acamprosate on 4-nitrophenol hydroxylase, a marker of CYP2E1 activity, was observed. As acamprosate enhanced oxidative stress only in the rats non-preferring ethanol, it could be expected that these adverse effects are not demonstrated in alcohol-dependent humans treated with acamprosate.

Reduction in voluntary ethanol intake following repeated oral administration of Jodina rhombifolia lyophilized aqueous extract in male Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Jodina rhombifolia (Hook. & Arn.) Reissek (SANTALACEAE) is utilized in Argentine folk medicine for the treatment of alcoholism.

AIM OF THE STUDY

To evaluate the antialcoholic activity of Jodina rhombifolia lyophilized aqueous extract (JRLE) in male Wistar rats.

MATERIALS AND METHODS

Rats were housed individually in standard plastic cages with wood chip bedding. Throughout the duration of experiment, ethanol was offered in the standard home-cage; two-bottle free-choice regimen between an ethanolic solution (20% in tap water, v/v) and tap water with unlimited access for 24h per day for 10 consecutive days. Rats were administrated intragastrically twice daily (1 ml/200 g) for 10 consecutive days, with the control vehicle (distilled water) or one of the doses of JRLE (125, 250 and 500 mg/Kg weight). Body weight, ethanol, water and food intake were measured every day at the same hour during the 10 days of experimentation.

RESULTS

The reducing effect of JRLE on daily ethanol intake was evidenced from the first day of treatment and persisted throughout the entire treatment period. The treatment did not significantly affect daily water intake neither the body weight gain. Daily food intake was higher in rat groups treated with JRLE.

CONCLUSION

The results obtained in the present preliminary study show that repeated administration of JRLE, markedly reduces ethanol voluntary intake in male Wistar rats. The reduction of consumption was of remarkable magnitude and stable during the treatment 10-days.

Treatment of alcohol dependence: recent progress and reduction of consumption

Alcohol dependence (AD) is a major public health problem. Currently, three drugs for the treatment of AD have been approved by both the European Medicines Agency (EMA) and the Food and Drug Administration (FDA): acamprosate, disulfiram, and oral naltrexone. The FDA also approved the use of long-acting injectable naltrexone. In Austria and in Italy sodium oxybate is also approved. The EMA's Committee for Medicinal Products for Human Use has recently granted marketing authorization for nalmefene for the reduction of alcohol consumption. Many patients, while accepting the problem, are unable or unwilling to completely stop consuming alcohol, leading to an inevitable deterioration over time of their psycho-physical state, and social and family relationships. It is appropriate to offer these patients the opportunity to significantly reduce their consumption of alcohol. The reduction may be an opportunity to prepare the individual for achieving complete abstinence. Abstinence should always be the main goal. Currently, nalmefene is the only drug that has been authorized for the reduction of alcohol consumption. Its association with psycho-social support is mandatory; it is taken on an "as-needed" basis, which should preferably be 1-2 hours before the possible intake of alcohol. The trials showed a significant reduction in alcohol consumption, which resulted in a significant reduction in morbidity and mortality. Reducing consumption allows a decrease in the progression of numerous alcohol-induced chronic diseases, as well as a reduction in psycho-physical damage, acts of violence, motor vehicle accidents, and accidents at work, which in turn means fewer healthcare costs.

Chronic treatment with novel brain-penetrating selective NOP receptor agonist MT-7716 reduces alcohol drinking and seeking in the rat

Since its discovery, the nociceptin/orphanin FQ (N/OFQ)-NOP receptor system has been extensively investigated as a promising target to treat alcoholism. Encouraging results obtained with the endogenous ligand N/OFQ stimulated research towards the development of novel brain-penetrating NOP receptor agonists with a pharmacological and toxicological profile compatible with clinical development. Here we describe the biochemical and alcohol-related behavioral effects of the novel NOP receptor agonist MT-7716. MT-7716 has high affinity for human NOP receptors expressed in HEK293 cells with a Ki value of 0.21 nM. MT-7716 concentration-dependently stimulated GTPγ(35)S binding with an EC50 value of 0.30 nM and its efficacy was similar to N/OFQ, suggesting that MT7716 is a full agonist at NOP receptors. In the two bottle choice test MT-7716 (0, 0.3, 1, and 3 mg/kg, bid) given orally for 14 days dose-dependently decreased voluntary alcohol intake in Marchigian Sardinian rats. The effect became gradually stronger following repeated administration, and was still significant 1 week after discontinuation of the drug. Oral naltrexone (30 mg/kg, bid) for 14 days also reduced ethanol intake; however, the effect decreased over the treatment period and rapidly disappeared when drug treatment was discontinued. MT-7716 is also effective for preventing reinstatement caused by both ethanol-associated environmental stimuli and stress. Finally, to investigate the effect of MT-7716 on alcohol withdrawal symptoms, Wistar rats were withdrawn from a 7-day alcohol liquid diet. MT-7716 significantly attenuated somatic alcohol withdrawal symptoms. Together these findings indicate that MT-7716 is a promising candidate for alcoholism treatment remaining effective with chronic administration.

Alcohol use disorders and current pharmacological therapies: the role of GABA(A) receptors

Alcohol use disorders (AUD) are defined as alcohol abuse and alcohol dependence, which create large problems both for society and for the drinkers themselves. To date, no therapeutic can effectively solve these problems. Understanding the underlying mechanisms leading to AUD is critically important for developing effective and safe pharmacological therapies. Benzodiazepines (BZs) are used to reduce the symptoms of alcohol withdrawal syndrome. However, frequent use of BZs causes cross-tolerance, dependence, and cross-addiction to alcohol. The FDA-approved naltrexone and acamprosate have shown mixed results in clinical trials. Naltrexone is effective to treat alcohol dependence (decreased length and frequency of drinking bouts), but its severe side effects, including withdrawal symptoms, are difficult to overcome. Acamprosate showed efficacy for treating alcohol dependence in European trials, but two large US trials have failed to confirm the efficacy. Another FDA-approved medication, disulfiram, does not diminish craving, and it causes a peripheral neuropathy. Kudzu is the only natural medication mentioned by the National Institute on Alcohol Abuse and Alcoholism, but its mechanisms of action are not yet established. It has been recently shown that dihydromyricetin, a flavonoid purified from Hovenia, has unique effects on GABAA receptors and blocks ethanol intoxication and withdrawal in alcoholic animal models. In this article, we review the role of GABAA receptors in the treatment of AUD and currently available and potentially novel pharmacological agents.

Drinking through the pain

A feature of abusive alcohol drinking has been modeled successfully in experiments with rats. The experiments show that changes in NMDA signaling in specific neural circuits accompany the transition to aversion-resistant drinking.

[Electrophysiological study of acamprosate effects on frontal cortical neurons in rats]

The effect of drug for alcoholism treatment acamprosate (campral) on spontaneous electrical activity of frontal cortical neurons was studied in rats. Acamprosate after acute intraperitoneal administration (600 mg/kg) and microiontophoretic application reduced the frequency of spike activity in about 30 % of cells studied. The agent didn't change the magnitude and form of action potentials. Microiontophoretically applied acamprosate reduced the excitatory responses to ethanol electroosmotically applied to neurons at "small doses" (ejected current < 50 nA) and increased the value of neuronal depression induced by ethanol at the "large doses" (ejected current 50 nA). Effects of acamprosate were dose independent. It is suggested that acamprosate has no interaction with specific postsynaptic receptors and its action is determined by presynaptic mechanisms.

The glycine reuptake inhibitor Org24598 and acamprosate reduce ethanol intake in the rat; tolerance development to acamprosate but not to Org24598

Extracellular glycine modulates accumbal dopamine levels as well as ethanol-induced dopamine overflow. Glycine availability is also crucial for regulating alcohol consumption and the glycine transporter 1 (GlyT-1) inhibitor Org25935 robustly decreases alcohol intake in rats. To explore whether the alcohol-intake reducing effect of Org25935 is substance bound, we examined the effect of a different selective GlyT-1 inhibitor, Org24598, on ethanol consumption in rats and compared the effect with that of acamprosate, a drug currently in clinical use. We studied the effects of daily Org24598 and acamprosate injections on male Wistar rats with ~60% ethanol preference in a limited access two bottle free-choice model for 12 days, followed by alcohol deprivation for 14 days before a second test period of 10 days. Finally, rats underwent in vivo microdialysis where dopamine, glycine, taurine and β-alanine in n. accumbens were measured. Org24598 profoundly reduced ethanol intake and the effect remained throughout both treatment periods. Acamprosate promptly reduced ethanol intake, but on the third day tolerance developed to this effect and acamprosate failed to influence alcohol consumption during the second test period. Neither Org24598 nor acamprosate reduced water intake. Following the drinking study, the Org24598 group displayed higher basal accumbal dopamine levels compared with acamprosate and vehicle groups. Both Org24598 and acamprosate reduced the ethanol-induced dopamine response in n. accumbens. The study demonstrates a robust anti-alcohol intake effect of the GlyT-1 inhibitor Org24598, supporting the new concept that GlyT-1 inhibition reduces ethanol consumption. GlyT-1 inhibition may represent a new treatment principle for alcoholism that is superior to acamprosate.

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.

Effect of ganaxolone and THIP on operant and limited-access ethanol self-administration

Recent evidence suggests that GABA(A) receptor ligands may regulate ethanol intake via effects at both synaptic and extrasynaptic receptors. For example, the endogenous neurosteroid, allopregnanolone (ALLO) has a similar pharmacological profile as ethanol, and it alters ethanol intake in rodent models. Additionally, recent evidence suggests that δ-subunit-containing extrasynaptic GABA(A) receptors may confer high sensitivity to both ethanol and neurosteroids. The purpose of the present study was to determine the effects of ganaxolone (GAN; an ALLO analog) and gaboxadol (THIP; a GABA(A) receptor agonist with selectivity for the extrasynaptic δ-subunit) on ethanol intake, drinking patterns, and bout characteristics in operant and limited-access self-administration procedures. In separate studies, the effects of GAN (0-10 mg/kg) and THIP (2-16 mg/kg) were tested in C57BL/6J male mice provided with 2-h access to a two-bottle choice of water or 10% ethanol or trained to respond for 30 min of access to 10% ethanol. GAN had no overall significant effect on operant ethanol self-administration, but tended to decrease the latency to consume the first bout. In the limited-access procedure, GAN dose-dependently decreased ethanol intake. THIP dose-dependently decreased ethanol intake in both paradigms, altering both the consummatory and appetitive processes of operant self-administration as well as shifting the drinking patterns in both procedures. These results add to literature suggesting time-dependent effects of neurosteroids to promote the onset, and to subsequently decrease, ethanol drinking behavior, and they support a role for extrasynaptic GABA(A) receptor activation in ethanol reinforcement.

[Effect of disulfiram on energy metabolism (redox potential shift) coupled to paradoxical sleep episodes in rat cerebral cortex]

Disulfiram (DS) is widely used to treat patients with chronic alcoholism. DS treatment multiplies PS episodes. In this work, DS effect on the number of PS episodes and on the energy metabolism changes in the cerebral cortex (coupled to PS episodes) was investigated for the first time in rats. Polygraphic recording of the redox potential E (with platinum electrodes implanted in several cortical sites), electrocorticogram, neck electromyogram, and general motor activity were made in sleep-wake cycles. Rats received DS (100 mg/kg) with meals for two nights, after which the number of PS episodes increased almost twice during two subsequent sessions (prior to receiving DS). This was evidence of an increase in PS pressure coupled to a decrease of norepinephrine level in the brain. DS also evoked sharp decrease in the amount of the positive E shifts related to PS, which were replaced by the negative E shifts or by the two-phase E shifts (negative-positive waves). The absolute mean amplitude decreased both for the positive E shifts and the negative E shifts. These findings demonstrate prevailing glycolytic compartment as a source of fuel supporting PS and the inhibition in all brain energetic compartments. The data presented well agree with the conception that glycolysis becomes the main source for the brain activity under pathology conditions.

Tryptophan in alcoholism treatment I: kynurenine metabolites inhibit the rat liver mitochondrial low Km aldehyde dehydrogenase activity, elevate blood acetaldehyde concentration and induce aversion to alcohol

AIMS

The aims were to provide proofs of mechanism and principle by establishing the ability of kynurenine metabolites to inhibit the liver mitochondrial low K(m) aldehyde dehydrogenase (ALDH) activity after administration and in vivo, and to induce aversion to alcohol.

METHODS

Kynurenic acid (KA), 3-hydroxykynurenine (3-HK) and 3-hydroxyanthranilic acid (3-HAA) were administered to normal male Wistar rats and ALDH activity was determined both in vitro in liver homogenates and in vivo (by measuring blood acetaldehyde following ethanol administration). Alcohol consumption was studied in an aversion model in rats and in alcohol-preferring C57 mice.

RESULTS

ALDH activity was significantly inhibited by all three metabolites by doses as small as 1 mg/kg body wt. Blood acetaldehyde accumulation after ethanol administration was strongly elevated by KA and 3-HK and to a lesser extent by 3-HAA. All three metabolites induced aversion to alcohol in rats and decreased alcohol preference in mice.

CONCLUSIONS

The above kynurenine metabolites of tryptophan induce aversion to alcohol by inhibiting ALDH activity. An intellectual property covering the use of 3-HK and 3-HAA and derivatives thereof in the treatment of alcoholism by aversion awaits further development.

Tryptophan in alcoholism treatment II: inhibition of the rat liver mitochondrial low Km aldehyde dehydrogenase activity, elevation of blood acetaldehyde concentration and induction of aversion to alcohol by combined administration of tryptophan and benserazide

AIMS

The aims were to provide proofs of mechanism and principle by establishing the ability of the amino acid L-tryptophan (Trp) combined with the kynureninase inhibitor benserazide (BSZ) to inhibit the liver mitochondrial low K(m) aldehyde dehydrogenase (ALDH) activity after administration and in vivo and to induce aversion to alcohol.

METHODS

Trp, BSZ or both were administered to male Wistar rats and ALDH activity was determined both in vitro in liver homogenates and in vivo (by measuring acetaldehyde accumulation in blood after ethanol administration). Alcohol consumption was studied in an aversion model in rats and in alcohol-preferring C57 mice.

RESULTS

Combined administration of Trp + BSZ, but neither compound alone, produced a strong inhibition of ALDH activity and an increase in blood acetaldehyde concentration after ethanol, and induced aversion to alcohol in rats and decreased preference in mice. Another kynureninase inhibitor, carbidopa, induced aversion to alcohol by itself, which was reversed by Trp co-administration.

CONCLUSIONS

The present results establish a prior art for the use of a combination of Trp plus BSZ in the treatment of alcoholism by aversion, which merits rapid clinical development.

Systemic κ-opioid receptor antagonism by nor-binaltorphimine reduces dependence-induced excessive alcohol self-administration in rats

Altered dynorphin opioid peptide systems contribute to increased ethanol self-administration during withdrawal following chronic alcohol exposure. We previously identified that the κ-opioid receptor antagonist nor-binaltorphimine (nor-BNI) selectively reduced ethanol self-administration in dependent animals. The purpose of this study was twofold: (1) determine whether peripherally administered nor-BNI could reduce dependence-induced ethanol self-administration and (2) confirm the selective κ-opioid effects of nor-BNI by administering it 24 hours prior to ethanol self-administration sessions occurring during acute withdrawal. Nor-BNI decreased ethanol self-administration in ethanol-dependent animals, with no effect in nondependent animals. Thus, the κ-opioid/dynorphin system is a viable pharmacotherapeutic target for the treatment of alcoholism.

Noribogaine, but not 18-MC, exhibits similar actions as ibogaine on GDNF expression and ethanol self-administration

Ibogaine is a naturally occurring alkaloid that has been reported to decrease various adverse phenotypes associated with exposure to drugs of abuse and alcohol in human and rodent models. Unfortunately, ibogaine cannot be used as a medication to treat addiction because of severe side effects. Previously, we reported that the desirable actions of ibogaine to reduce self-administration of, and relapse to, alcohol consumption are mediated via the upregulation of the expression of the glial cell line-derived neurotrophic factor (GDNF) in the midbrain ventral tegmental area (VTA), and the consequent activation of the GDNF pathway. The ibogaine metabolite, noribogaine, and a synthetic derivative of ibogaine, 18-Methoxycoronaridine (18-MC), possess a similar anti-addictive profile as ibogaine in rodent models, but without some of its adverse side effects. Here, we determined whether noribogaine and/or 18-MC, like ibogaine, increase GDNF expression, and whether their site of action to reduce alcohol consumption is the VTA. We used SH-SY5Y cells as a cell culture model and found that noribogaine, like ibogaine, but not 18-MC, induces a robust increase in GDNF mRNA levels. Next, we tested the effect of intra-VTA infusion of noribogaine and 18-MC on rat operant alcohol self-administration and found that noribogaine, but not 18-MC, in the VTA decreases responding for alcohol. Together, our results suggest that noribogaine and 18-MC have different mechanisms and sites of action.

Cue-induced alcohol-seeking behaviour is reduced by disrupting the reconsolidation of alcohol-related memories

RATIONALE

In humans, the retrieval of memories associated with an alcohol-related experience frequently evokes alcohol-seeking behaviour. The reconsolidation hypothesis states that a consolidated memory could again become labile and susceptible to disruption after memory retrieval.

OBJECTIVES

The aim of our study was to examine whether retrieval of alcohol-related memories undergoes a reconsolidation process.

METHODS

For this purpose, male Wistar rats were trained to self-administer ethanol in the presence of specific conditioned stimuli. Thereafter, animals were left undisturbed in their home cages for the following 21 days. Memory retrieval was performed in a single 5-min exposure to all alcohol-associated stimuli. The protein synthesis inhibitor anisomycin, the non-competitive N-methyl-D: -aspartate (NMDA) receptor antagonist MK-801 and acamprosate, a clinically used drug known to reduce a hyper-glutamatergic state, were given immediately after retrieval of alcohol-related memories. The impact of drug treatment on cue-induced alcohol-seeking behaviour was measured on the following day and 7 days later.

RESULTS

Administration of both anisomycin and MK-801 reduced cue-induced alcohol-seeking behaviour, showing that memory reconsolidation was disrupted by these compounds. However, acamprosate had no effect on the reconsolidation process, suggesting that this process is not dependent on a hyper-glutamatergic state but is more related to protein synthesis and NMDA receptor activity.

CONCLUSIONS

Pharmacological disruption of reconsolidation of alcohol-associated memories can be achieved by the use of NMDA antagonists and protein synthesis inhibitors and may thus provide a potential new therapeutic strategy for the prevention of relapse in alcohol addiction.

The state of pharmacotherapy for the treatment of alcohol dependence

Pharmacotherapy, in conjunction with psychosocial interventions, is emerging as a valuable tool for alcohol dependence treatment. Currently, four agents are approved by the Food and Drug Administration for this purpose: disulfiram, acamprosate, oral naltrexone, and the once-monthly injectable, extended-release naltrexone. All four agents have demonstrated some ability to reduce drinking and/or increase time spent abstinent, but results have not always been consistent. Except disulfiram, which has an aversive mechanism of action, effective pharmacotherapies for alcohol dependence are thought to work by blocking the rewards of alcohol or stabilizing systems dysregulated by chronic alcohol intake. Topiramate and baclofen have also demonstrated some efficacy in treating alcohol dependence. The efficacies of many of these regimens are modest and are limited by patient nonadherence to treatment and disease heterogeneity. Pharmacotherapeutic effectiveness could be enhanced through increased knowledge of the pathophysiology of alcohol dependence, through the identification of predictors of response to specific medications, and by modalities that improve medication adherence.

Tolerance to disulfiram induced by chronic alcohol intake in the rat

BACKGROUND

Disulfiram, an inhibitor of aldehyde dehydrogenase used in the treatment of alcoholism, is an effective medication when its intake is supervised by a third person. However, its therapeutic efficacy varies widely, in part due to the fact that disulfiram is a pro-drug that requires its transformation into an active form and because it shows a wide range of secondary effects which often prevent the use of doses that ensure full therapeutic effectiveness. In this preclinical study in rats we report the development of tolerance to disulfiram induced by the chronic ingestion of ethanol, an additional source of variation for the actions of disulfiram with possible therapeutic significance, We also addresses the likely mechanism of this effect.

METHODS

Wistar-derived rats bred for generations as high ethanol drinkers (UChB) were trained for either 3 days (Group A) or 30 days (Group B) to choose between ethanol (10% v/v) or water, which were freely available from 2 bottles on a 24-hour basis. Subsequently, animals in both groups were administered disulfiram or cyanamide (another inhibitor of aldehyde dehydrogenase) and ethanol intake in this free choice paradigm was determined. Animals were also administered a standard dose of 1 g ethanol/kg (i.p) and arterial blood acetaldehyde was measured.

RESULTS

Disulfiram (12.5 and 25 mg/kg) and cyanamide (10 mg/kg) markedly inhibited ethanol intake (up to 60 to 70%) in animals that had ethanol access for only 3 days (Group A). However both drugs were inactive in inhibiting ethanol intake in animals that had consumed ethanol for 30 days (Group B). Following the injection of 1 g ethanol/kg, arterial blood acetaldehyde levels reached levels of 150 and 300 microM for disulfiram and cyanamide respectively, values which were virtually identical regardless of the length of prior ethanol intake of the animals.

CONCLUSIONS

Chronic ethanol intake in high-drinker rats leads to marked tolerance to the aversive effects of disulfiram and cyanamide on ethanol intake despite the presence of consistently high levels of blood acetaldehyde. These findings may have implications for the use of disulfiram for the treatment of alcoholism in humans.

Effects of naltrexone, duloxetine, and a corticotropin-releasing factor type 1 receptor antagonist on binge-like alcohol drinking in rats

A 'binge' is defined by National Institute on Alcohol Abuse and Alcoholism as an excessive pattern of alcohol drinking that produces blood-alcohol levels (BALs) greater than 0.08 g% within a 2-h period and may or may not be associated with dependence. The purpose of this investigation was to explore the effects of several neuropharmacological agents in an animal model in which outbred rats voluntarily and orally self-administer pharmacologically meaningful alcohol doses that produce BALs >or=0.08 g% in daily limited access two-bottle choice and operant drinking sessions. Rats were trained to self-administer either 10% (w/v) alcohol solution sweetened with 'supersac' (3% glucose+0.125% saccharin) or supersac alone versus water in a two-bottle choice or operant situation during 30-min daily sessions. Rats were then injected systemically with multiple doses of duloxetine, naltrexone, and the corticotropin-releasing factor antagonist, MPZP, in Latin-square designs. Alcohol binge drinkers reliably consumed amounts of alcohol sufficient to produce BALs >or=0.08 g%. Duloxetine dose-dependently suppressed two-bottle choice alcohol binge drinking and operant alcohol responding as well as operant supersac responding, but did not affect two-bottle choice supersac drinking. Naltrexone-suppressed alcohol binge drinking at very low doses and suppressed supersac drinking at moderate-to-high doses. MPZP did not affect alcohol or supersac consumption. Different profiles for drugs that suppress binge-like alcohol drinking compared with dependence-induced drinking provide a heuristic foundation for future medications development.

Acamprosate attenuates cocaine- and cue-induced reinstatement of cocaine-seeking behavior in rats

RATIONALE

Acamprosate (calcium acetylhomotaurinate) is a glutamatergic neuromodulator used for the treatment of alcoholism, but its potential efficacy in the treatment of psychostimulant addiction has not been explored.

OBJECTIVES

The purpose of this study was to assess the effects of acamprosate on cocaine-stimulated locomotor activity, cocaine self-administration, and cue- and cocaine-induced reinstatement of cocaine-seeking behavior.

MATERIALS AND METHODS

All experiments utilized once-daily treatment for 5 consecutive days. First, the effects of saline or acamprosate (100, 300, or 500 mg/kg intraperitoneally) on body weight were examined. On the last day of treatment, locomotor activity was assessed before and after drug treatment, after which all animals received an acute challenge of cocaine (10 mg/kg). Next, a separate group of rats were trained to intravenously (IV) self-administer cocaine (0.6 mg/kg per infusion), subjected to extinction procedures, and then tested for effects of acamprosate on cue- or cocaine-induced reinstatement. A third group of rats was trained to self-administer cocaine as described above and were treated with saline or acamprosate before daily IV self-administration sessions.

RESULTS

Repeated administration of 500 mg/kg acamprosate but not lower doses produced reductions in both body weight and spontaneous locomotor activity, and thus this dose was not tested further. Acamprosate at 300 mg/kg but not 100 mg/kg attenuated both cocaine- and cue-induced reinstatement without altering baseline patterns of cocaine self-administration or cocaine-stimulated hyperlocomotion.

CONCLUSIONS

Acamprosate attenuates both drug- and cue-induced reinstatement of cocaine-seeking behavior, suggesting that this compound may serve as a potential treatment for preventing relapse in cocaine-addicted humans.

The effect of naltrexone and acamprosate on cue-induced craving, autonomic nervous system and neuroendocrine reactions to alcohol-related cues in alcoholics

INTRODUCTION

Acamprosate and naltrexone have been shown to be effective in relapse prevention of alcoholism. It is hypothesized that naltrexone exerts its effects primarily on cue-induced craving and neuroendocrine cue reactivity, whereas acamprosate exerts its effect primarily on autonomic nervous system reactions to alcohol-related cues.

EXPERIMENTAL PROCEDURES

In a randomized double-blind experiment, 131 abstinent alcoholics received either acamprosate (n=56), naltrexone (n=52) or placebo (n=23) for three weeks and participated in two cue-exposure sessions: the first the day before and the second at the last day of medication.

RESULTS

Consistent with the hypotheses, naltrexone reduced craving more than acamprosate, and acamprosate reduced heart rate more than naltrexone. No medication effect was found on cue-induced cortisol.

DISCUSSION

The findings provide some evidence for differential effects of naltrexone and acamprosate: naltrexone may exert its effect, at least partly, by the reduction of cue-induced craving, whereas acamprosate may exert its effect, at least partly, by the reduction of autonomic nervous system reactions to alcohol-related cues.

Inhibition of proteasome activity, nuclear factor-KappaB translocation and cell survival by the antialcoholism drug disulfiram

The proteasome pathway is an important target for anticancer drug development. Here, we identify the antialcoholism drug disulfiram and its analogue pyrrolidine dithiocarbamate (PDTC) as inhibitors of the 26S proteasome activity in a cell-based screening assay. As expected for proteasome inhibitors, these compounds also inhibited TNF-alpha-induced nuclear factor-KappaB (NF-KappaB) translocation and were cytotoxic. Disulfiram was more cytotoxic against chronic lymphocytic leukemia cells compared to peripheral blood mononuclear cells (PBMC) at clinically achievable concentrations. Proteasome and NF-KappaB inhibition were achieved with a potency in the same range as that of the clinically used proteasome inhibitor bortezomib. Disulfiram was also able to induce accumulation of p27(Kip1) and to prolong the half-life of c-Myc, both targets for proteasome-dependent degradation. It is concluded that the previously observed antitumoral and NF-KappaB inhibiting activity of disulfiram and PDTC could be attributed to their inhibition of the 26S proteasome.

Disulfiram effects on responses to intravenous cocaine administration

Disulfiram has been studied as a treatment for cocaine dependence. We report results of a randomized, double-blind, placebo-controlled, within-subject study to examine the interaction of disulfiram with intravenous cocaine.

METHODS

Non-treatment-seeking, cocaine-dependent, volunteers participated in serial experiments in which they received disulfiram placebo, 62.5 or 250 mg/day on days 1-6. On days 4-6, participants received a morning disulfiram dose 2 h prior to a scheduled session in which they were administered intravenous cocaine placebo, 0.25 mg/kg (n=9) or 0.5 mg/kg (n=3) over 1 min. Blood, cardiovascular and subjective measures were collected. Seven days of washout occurred between disulfiram conditions.

RESULTS

Following active disulfiram treatments and cocaine 0.25 mg/kg administration, plasma cocaine AUC (0-480 min) was increased (p=0.003 and 0.001) and cocaine clearance decreased (p<0.001). Disulfiram treatments also decreased cocaine clearance for the 0.5 mg/kg cocaine dose (p=0.002 and<0.001). Neither disulfiram dose with cocaine altered cardiovascular responses relative to cocaine alone. Following cocaine 0.25 mg/kg, 'any high' (p=0.021 and 0.019), 'cocaine high' (p=0.017 and 0.018) and 'rush' (p=0.013 and 0.047) significantly decreased with either disulfiram dose.

CONCLUSIONS

Disulfiram decreased cocaine clearance without toxicity. Cocaine 'high' and 'rush' were diminished. Disulfiram may be a promising pharmacotherapy in selected cocaine dependent individuals.

Evidence for the role of dopamine D3 receptors in oral operant alcohol self-administration and reinstatement of alcohol-seeking behavior in mice

The present study examined the effects of the acute intraperitoneal (i.p.) administration of the selective dopamine (DA) D(3) receptor antagonist SB-277011A (10, 20 or 30 mg/kg i.p.) on the oral operant self-administration of alcohol in male C57BL/6N mice. These effects were compared with those of naltrexone (0.5, 1 and 2 mg/kg i.p.) and acamprosate (100, 200 and 400 mg/kg i.p.). Compared with vehicle, the acute administration of SB-277011A (10 or 20 mg/kg) did not significantly alter the operant self-administration of alcohol, whereas the 30 mg/kg dose significantly reduced alcohol intake (g/kg), the number of reinforcers, and the number of active lever presses. The oral self-administration of alcohol was not significantly altered by the acute administration of either naltrexone or acamprosate, compared with vehicle-treated mice. SB-277011A, naltrexone and acamprosate were also tested in a model of drug/cue-triggered reinstatement of alcohol-seeking behavior. In this model, neither naltrexone (2 mg/kg) nor acamprosate (400 mg/kg) prevented relapse to alcohol-seeking behavior. In contrast, SB-277011A significantly reduced reinstatement of alcohol seeking in a dose-dependent manner. Provided these results can be extrapolated to humans, they suggest that selective DA D(3) receptor antagonists may be useful in the pharmacotherapeutic management of alcohol intake and prevention of relapse to alcohol-seeking behavior.

Influence of age at drinking onset on the alcohol deprivation effect and stress-induced drinking in female rats

We have recently observed increased stress responsiveness with regard to alcohol consumption in male rats that consumed alcohol since their adolescent period. Thus, early age at drinking onset can induce enhanced stress-induced alcohol drinking in male rats. However, it is not known whether female rats respond in a similar way. Therefore, we compared the drinking behavior of two female Wistar rat groups--one that acquired alcohol consumption during adolescence (adolescent group) and the other that acquired their drinking during adulthood (adult group) in a model of long-term voluntary alcohol drinking with repeated deprivation and stress phases. Furthermore, we studied the influence of age at drinking onset on the efficacy of acamprosate treatment. Thirty-nine female Wistar rats aged 31 days (adolescents) and 71 days (adults) were given ad libitum access to water, as well as to 5% and 20% ethanol solutions during an observation period of 29 weeks. A deprivation phase of 14 days was introduced following 8 weeks of access to alcohol in order to measure the alcohol deprivation effect (ADE). After 15 and 25 weeks of alcohol access, all animals were subjected for 3 consecutive days of forced swim and electric foot-shock stress, respectively. After 29 weeks of access to alcohol all animals underwent a second deprivation phase and the subsequent ADE was measured either under acamprosate (200 mg/kg) or vehicle treatment. Drinking before the first deprivation phase was not different between animal groups. However, the expression of the first ADE was more pronounced in adult female rats and alcohol intake stayed increased for the remainder of the experiment in the adult group. Both repeated swim stress and foot-shock stress produced a more pronounced increase in ethanol consumption in the adolescent group compared to the adult group. Acamprosate reduced relapse-like drinking in the adult female rat group. However, it had no effect on the ADE in the adolescent group. In conclusion, female rats that initiate alcohol consumption during adolescence might be more susceptible to stress-induced alcohol consumption. Adolescent alcohol drinking might also result in a reduced response to acamprosate.

Behavioral and neurochemical interactions between Group 1 mGluR antagonists and ethanol: potential insight into their anti-addictive properties

Blockade of the mGluR5 subtype of Group 1 metabotropic glutamate receptor (mGluRs) reduces the rewarding effects of ethanol (EtOH), while the effects of mGluR1a blockade remain under-investigated. The present study compared the effects of pretreatment with the mGluR5 antagonist MPEP and the mGluR1a antagonist CPCCPOEt upon behavioral and neurochemical variables associated with EtOH reward in alcohol-preferring C57BL/6J mice. Pretreatment with either antagonist (0-10 mg/kg, IP) dose-dependently reduced measures of EtOH reward in an operant self-administration paradigm and the maximally effective antagonist dose (10 mg/kg) also blocked the expression of EtOH-induced place conditioning, as well as EtOH consumption under 24-h free-access conditions. MPEP pretreatment did not significantly alter the EtOH dose-locomotor response function; however, it prevented EtOH-induced changes in extracellular dopamine, glutamate and GABA in the nucleus accumbens (NAC). In contrast, CPCCOEt shifted the EtOH dose-response function downwards, enhanced the capacity of higher EtOH doses to elevate NAC levels of GABA and lowered extracellular dopamine and glutamate below baseline following EtOH injection. It is suggested that the "anti-alcohol" effects of MPEP may involve an attenuation of the neurochemical signals mediating EtOH reward, whereas those of CPCCOEt may involve an increased sensitivity to the inhibitory effects of EtOH upon brain and behavior.

Delta receptor antagonism, ethanol taste reactivity, and ethanol consumption in outbred male rats

Naltrexone, a nonspecific opioid antagonist, produces significant changes in ethanol responsivity in rats by rendering the taste of ethanol aversive as well as producing a decrease in voluntary ethanol consumption. The present study investigated the effect of naltrindole, a specific antagonist of delta opioid receptors, on ethanol taste reactivity and ethanol consumption in outbred rats. In the first experiment, rats received acute treatment of naltrexone, naltrindole, or saline followed by the measurement of ethanol consumption in a short-term access period. The second experiment involved the same treatments and investigated ethanol palatability (using the taste-reactivity test) as well as ethanol consumption. Results indicated that treatment with 3 mg/kg naltrexone significantly affected palatability (rendered ethanol more aversive, Experiment 2) and decreased voluntary ethanol consumption (Experiments 1 and 2). The effects of naltrindole were inconsistent. In Experiment 1, 8 mg/kg naltrindole significantly decreased voluntary ethanol consumption but this was not replicated in Experiment 2. The 8 mg/kg dose produced a significant increase in aversive responding (Experiment 2) but did not affect ingestive responding. Lower doses of naltrindole (2 and 4 mg/kg) were ineffective in altering rats' taste-reactivity response to and consumption of ethanol. While these data suggest that delta receptors are involved in rats' taste-reactivity response to ethanol and rats' ethanol consumption, it is likely that multiple opioid receptors mediate both behavioral responses.

Substance use disorders and schizophrenia: A question of shared glutamatergic mechanisms

Schizophrenia is noted for the remarkably high prevalence of substance use disorders (SUDs) including nicotine (>85%), alcohol and stimulants. Mounting evidence supports the hypothesis that the endophenotype of schizophrenia involves hypofunction of a subpopulation of cortico-limbic NMDA receptors. Low doses of NMDA receptor antagonists such as ketamine replicate in normal volunteers positive, negative and cognitive symptoms of schizophrenia as well as associated physiologic abnormalities such as eye tracking and abnormal event related potentials. Genetic studies have identified putative risk genes that directly or indirectly affect NMDA receptors including D-amino acid oxidase, its modulator G72, proline oxidase, mGluR3 and neuregulin. Clinical trials have shown that agents that directly or indirectly enhance the function of the NMDA receptor at its glycine modulatory site (GMS) reduce negative symptoms and in the case of D-serine and sarcosine improve cognition and reduce positive symptoms in schizophrenic subjects receiving concurrent anti-psychotic medications. Notably, the GMS partial agonist D-cycloserine exacerbates negative symptoms in clozapine responders whereas full agonists, glycine and D-serine have no effects, suggesting clozapine may act indirectly as a full agonist at the GMS of the NMDA receptor. Clozapine treatment is uniquely associated with decreased substance use in patients with schizophrenia, even without psychologic intervention. Given the role of NMDA receptors in the reward circuitry and in substance dependence, it is reasonable to speculate that NMDA receptor dysfunction is a shared pathologic process in schizophrenia and co-morbid SUDs.

Effects of treatment with acamprosate on β-endorphin plasma concentration in humans with high alcohol preference

Treatment with acamprosate, a compound used for relapse prevention treatment of alcoholism, was recently shown to be associated with increased plasma concentration of beta-endorphin in rats selectively bred for high alcohol preference. The aim of our study was to prove this result in a comparative clinical study with a corresponding design. We studied 51 alcohol dependent patients following alcohol withdrawal during treatment with acamprosate versus placebo for 4 weeks. Data were analyzed for patients with high alcohol preference (HP) and low alcohol preference (LP) by dichotomizing the sample according to median alcohol intake prior to detoxification. In line with pre-clinical data, beta-endorphin plasma concentration in HP patients was significantly lower compared with LP patients. Four weeks of treatment with acamprosate resulted in a significantly increased beta-endorphin plasma concentration compared with placebo and a significant difference in HP patients but not in LP patients. In conclusion, acamprosate seems to modulate the endogenous opioid system. Our data are in accordance with the assumption that the effect of acamprosate on endorphin plasma concentrations is mainly based on the effect in the high preferring subgroup. Since beta-endorphin deficiency was earlier associated with alcohol craving and anxiety during withdrawal, abstinence maintaining effects of acamprosate might at least be partially related with the ability to modulate opioidergic activity especially in the subsample of HP patients with an attenuated opioidergic activity during this state.

Suppression of alcohol consumption in C57Bl/6 mice after intranasal administration of antiserotonin antibodies

Experiments on C57Bl/6 mice under conditions of free choice between alcohol and water for 10 months showed that intranasal administration with antiserotonin antibodies in doses of 30 and 15 microg/kg for 2 week decreased alcohol consumption over 1 month after treatment.

Hypothalamic-pituitary-adrenocortical axis activity: a target of pharmacological anticraving treatment?

BACKGROUND

An association between the activity of the hypothalamic-pituitary-adrenocortical (HPA) axis and alcohol intake behavior is currently discussed. We examined the relationship between efficacy of pharmacological anticraving treatment and HPA axis activity in the relapse prevention treatment of alcoholism.

METHODS

In 160 patients suffering from alcoholism, we measured plasma adrenocorticotropic hormone (ACTH) and cortisol during placebo-controlled relapse prevention treatment with naltrexone and/or acamprosate.

RESULTS

In the placebo group, ACTH and cortisol decreased during early abstinence. Treatment with naltrexone and acamprosate prevented this course. Increased ACTH and cortisol during treatment was associated with a reduced risk of relapse.

CONCLUSIONS

These findings suggest that heightened HPA responsiveness might contribute to relapse-preventing effects of anticraving compounds in alcoholism.

Drug adjuncts for treating alcohol dependence

Three drugs are approved by the US Food and Drug Administration for treating alcoholism: disulfiram, naltrexone, and acamprosate. Drugs approved for other indications that are being used experimentally or "off-label" include nalmafene, topiramate, and ondansetron. As we learn more about the pathophysiologic basis of alcoholism, it is hoped that novel drugs can be developed to help people with alcohol dependence achieve abstinence, and as a result, curb alcohol-related morbidity.