The role of the opioid system in alcohol dependence

Novel medications for problematic alcohol use

Alcohol-related harm, a major cause of disease burden globally, affects people along a spectrum of use. When a harmful pattern of drinking is present in the absence of significant behavioral pathology, low-intensity brief interventions that provide information about health consequences of continued use provide large health benefits. At the other end of the spectrum, profound behavioral pathology, including continued use despite knowledge of potentially fatal consequences, warrants a medical diagnosis, and treatment is strongly indicated. Available behavioral and pharmacological treatments are supported by scientific evidence but are vastly underutilized. Discovery of additional medications, with a favorable balance of efficacy versus safety and tolerability can improve clinical uptake of treatment, allow personalized treatment, and improve outcomes. Here, we delineate the clinical conditions when pharmacotherapy should be considered in relation to the main diagnostic systems in use and discuss clinical endpoints that represent meaningful clinical benefits. We then review specific developments in three categories of targets that show promise for expanding the treatment toolkit. GPCRs remain the largest category of successful drug targets across contemporary medicine, and several GPCR targets are currently pursued for alcohol-related indications. Endocrine systems are another established category, and several promising targets have emerged for alcohol indications. Finally, immune modulators have revolutionized treatment of multiple medical conditions, and they may also hold potential to produce benefits in patients with alcohol problems.

Improvements in recovery capital are associated with decreased alcohol use in a primary opioid use disorder treatment-seeking cohort

BACKGROUND AND OBJECTIVES

Comorbid substance use can negatively impact multiple aspects of treatment for patients with an opioid use disorder (OUD). We investigated if treatment for OUD led to improvements in patients' recovery capital (RC) overtime, and whether there were associated changes in co-occurring alcohol use.

METHODS

Participants (n = 133) were patients with OUD seeking outpatient treatment, who completed the Assessment of Recovery Capital (ARC) and reported drinking days per 30-day period thrice over the 6-month study. No specific treatments targeting alcohol were used. Two different models were employed to assess changes in total ARC score and adjusted odds ratio (aOR) for past 30-day abstinence.

RESULTS

Baseline mean ARC scores were 36.6 and significantly increased to mean score of 41.2 at study end. Ninety-one participants (68.4%) reported no alcohol use at baseline, and 97 (78.9%) reported no use in the previous 30 days at study endpoint. For each increase in ARC, there was an aOR 1.07 (confidence interval [CI]: 1.02-1.13) for past 30-day abstinence. Considering ARC standard deviation of 10.33 over all measurements, this equates to an aOR of 2.10 (CI: 1.22-3.62) for past 30-day abstinence.

DISCUSSION AND CONCLUSIONS

We saw significantly increased aOR for past 30-day abstinence as RC improved in an OUD treatment-seeking population. This difference was not caused by differences in ARC between study completers and noncompleters.

SCIENTIFIC SIGNIFICANCE

Showcases how RC growth may be protective of past 30-day alcohol use in an OUD cohort and adds specific aOR for abstinence per ARC increase.

Naltrexone blocks alcohol-induced effects on kappa-opioid receptors in the plasma membrane

Naltrexone (NTX), a homologue of the opiate antidote naloxone, is an orally active long-acting mu-opioid receptor (MOP) antagonist used in the treatment of opiate dependence. NTX is also found to relieve craving for alcohol and is one of the few FDA-approved drugs for alcohol use disorder (AUD). Reports that NTX blocks the actions of endogenous opioids released by alcohol are not convincing, suggesting that NTX interferes with alcohol actions by affecting opioid receptors. MOP and kappa-opioid receptor (KOP) are structurally related but functionally different. MOP is mainly located in interneurons activated by enkephalins while KOP is located in longer projections activated by dynorphins. While the actions of NTX on MOP are well established, the interaction with KOP and addiction is not well understood. We used sensitive fluorescence-based methods to study the influence of alcohol on KOP and the interaction between KOP and NTX. Here we report that alcohol interacts with KOP and its environment in the plasma membrane. These interactions are affected by NTX and are exerted both on KOP directly and on the plasma membrane (lipid) structures ("off-target"). The actions of NTX are stereospecific. Selective KOP antagonists, recently in early clinical trials for major depressive disorder, block the receptor but do not show the full action profile of NTX. The therapeutic effect of NTX treatment in AUD may be due to direct actions on KOP and the receptor environment.

Theoretical Frameworks and Mechanistic Aspects of Alcohol Addiction: Alcohol Addiction as a Reward Deficit/Stress Surfeit Disorder

Alcohol use disorder (AUD) can be defined by a compulsion to seek and take alcohol, the loss of control in limiting intake, and the emergence of a negative emotional state when access to alcohol is prevented. Alcohol use disorder impacts multiple motivational mechanisms and can be conceptualized as a disorder that includes a progression from impulsivity (positive reinforcement) to compulsivity (negative reinforcement). Compulsive drug seeking that is associated with AUD can be derived from multiple neuroadaptations, but the thesis argued herein is that a key component involves the construct of negative reinforcement. Negative reinforcement is defined as drug taking that alleviates a negative emotional state. The negative emotional state that drives such negative reinforcement is hypothesized to derive from the dysregulation of specific neurochemical elements that are involved in reward and stress within basal forebrain structures that involve the ventral striatum and extended amygdala, respectively. Specific neurochemical elements in these structures include decreases in reward neurotransmission (e.g., decreases in dopamine and opioid peptide function in the ventral striatum) and the recruitment of brain stress systems (e.g., corticotropin-releasing factor [CRF]) in the extended amygdala, which contributes to hyperkatifeia and greater alcohol intake that is associated with dependence. Glucocorticoids and mineralocorticoids may play a role in sensitizing the extended amygdala CRF system. Other components of brain stress systems in the extended amygdala that may contribute to the negative motivational state of withdrawal include norepinephrine in the bed nucleus of the stria terminalis, dynorphin in the nucleus accumbens, hypocretin and vasopressin in the central nucleus of the amygdala, and neuroimmune modulation. Decreases in the activity of neuropeptide Y, nociception, endocannabinoids, and oxytocin in the extended amygdala may also contribute to hyperkatifeia that is associated with alcohol withdrawal. Such dysregulation of emotional processing may also significantly contribute to pain that is associated with alcohol withdrawal and negative urgency (i.e., impulsivity that is associated with hyperkatifeia during hyperkatifeia). Thus, an overactive brain stress response system is hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence, and to contribute to the compulsivity of AUD. The combination of the loss of reward function and recruitment of brain stress systems provides a powerful neurochemical basis for a negative emotional state that is responsible for the negative reinforcement that at least partially drives the compulsivity of AUD.

Inflammatory pain affects alcohol intake in a dose-dependent manner in male rats in the intermittent access model

Introduction

Epidemiological studies have shown that there is a relation between pain and alcohol use disorder (AUD). Persistent pain is directly correlated with an increment in alcohol consumption and an increased risk of developing an AUD. Greater levels of pain intensity and unpleasantness are associated with higher levels of relapse, an increase in alcohol consumption, rates of hazardous drinking, and delay to seek for treatment. However, this interaction has not been deeply studied in the preclinical setting.

Methods

Here, we aim to evaluate how inflammatory pain affects levels of alcohol drinking in male and female rats with a history of alcohol. For that, we used an intermittent access 2-bottle choice paradigm combined with the complete Freund Adjuvant (CFA) model of inflammatory pain.

Results

Our results show that CFA-induced inflammatory pain does not alter total intake of 20% alcohol in male or female rats. Interestingly, in males, the presence of CFA-induced inflammatory pain blunts the decrease of alcohol intake when higher concentrations of alcohol are available, whereas it does not have an effect on intake at any concentration in female rats.

Conclusion

Altogether, this study provides relevant data and constitutes an important contribution to the study of pain and AUD and it highlights the necessity to design better behavioral paradigms in animal models that are more translational and reflect current epidemiological findings.

Alcohol and other drug use before custody among Aboriginal and non-Aboriginal people in New South Wales, Australia

OBJECTIVE

Alcohol and other drug (AoD) use is a significant factor in the poor health status of people in prison. Our aim is to explore associations of alcohol consumption with tobacco and illicit drug use among Aboriginal and non-Aboriginal people in prison to inform health services, clinical care and support.

METHODS

We analysed the alcohol, tobacco and illicit drug use data of the 2015 Network Patient Health Survey of adults in custody in New South Wales (n=1,132). A comparative analysis of Aboriginal to non-Aboriginal participants including bi-variant and multivariant analysis was undertaken.

RESULTS

Significantly more Aboriginal than non-Aboriginal participants reported alcohol consumption before prison that was consistent with possible dependence. More Aboriginal than non-Aboriginal participants used cannabis on a daily or almost on daily basis before prison. There was significant association between alcohol and cannabis use among Aboriginal participants.

CONCLUSIONS

There are differences in Aboriginal and non-Aboriginal AoD use patterns, which should be considered when providing treatment and support programs within and post-release from prison.

IMPLICATIONS FOR PUBLIC HEALTH

Specific programs are needed to assist Aboriginal people in this population who co-use alcohol and cannabis.

Stress-related neuropeptide systems as targets for treatment of alcohol addiction: A clinical perspective

Alcohol use is a major cause of disability and death globally. These negative consequences disproportionately affect people who develop alcohol addiction, a chronic relapsing condition characterized by increased motivation to use alcohol, choice of alcohol over healthy, natural rewards, and continued use despite negative consequences. Available pharmacotherapies for alcohol addiction are few, have effect sizes in need of improvement, and remain infrequently prescribed. Research aimed at developing novel therapeutics has in large part focused on attenuating pleasurable or "rewarding" properties of alcohol, but this targets processes that primarily play a role as initiation factors. As clinical alcohol addiction develops, long-term changes in brain function result in a shift of affective homeostasis, and rewarding alcohol effects become progressively reduced. Instead, increased stress sensitivity and negative affective states emerge in the absence of alcohol and create powerful incentives for relapse and continued use through negative reinforcement, or "relief." Based on research in animal models, several neuropeptide systems have been proposed to play an important role in this shift, suggesting that these systems could be targeted by novel medications. Two mechanisms in this category, antagonism at corticotropin-releasing factor type 1, and neurokinin 1/substance P receptors, have been subject to initial evaluation in humans. A third, kappa-opioid receptor antagonism, has been evaluated in nicotine addiction and could soon be tested for alcohol. This paper discusses findings with these mechanisms to date, and their prospects as future targets for novel medications.

Genome-Wide Association Study Identifies Candidate Loci Associated with Opioid Analgesic Requirements in the Treatment of Cancer Pain

Considerable individual differences have been widely observed in the sensitivity to opioids. We conducted a genome-wide association study (GWAS) in patients with cancer pain to identify potential candidate single-nucleotide polymorphisms (SNPs) that contribute to individual differences in opioid analgesic requirements in pain treatment by utilizing whole-genome genotyping arrays with more than 650,000 markers. The subjects in the GWAS were 428 patients who provided written informed consent and underwent treatment for pain with opioid analgesics in a palliative care unit at Higashi-Sapporo Hospital. The GWAS showed two intronic SNPs, rs1283671 and rs1283720, in the ANGPT1 gene that encodes a secreted glycoprotein that belongs to the angiopoietin family. These two SNPs were strongly associated with average daily opioid requirements for the treatment of pain in both the additive and recessive models (p < 5.0000 × 10−8). Several other SNPs were also significantly associated with the phenotype. In the gene-based analysis, the association was significant for the SLC2A14 gene in the additive model. These results indicate that these SNPs could serve as markers that predict the efficacy of opioid analgesics in cancer pain treatment. Our findings may provide valuable information for achieving satisfactory pain control and open new avenues for personalized pain treatment.

Effect of Extract of Black Sticky Rice with Giant Embryo on Alcohol Cravings of Korean Social Drinkers: A 12-Week Randomized, Placebo-Controlled Trial

We investigated the effect of black sticky rice with giant embryo (BSRGE) extract known to contain high levels of gamma-aminobutyric acid (GABA) on alcohol cravings in social drinkers. A total of 41 subjects were divided into a BSRGE extract group (G group: n = 21) and a placebo group (P group: n = 20), and a randomized placebo-controlled experiment was performed for 12 weeks. The G group took the BSRGE extracts that contained 30 mg of GABA per day. (1) In the Pennsylvania Alcohol Craving Scale, there was a tendency for time and group interaction between the two groups (P = .087) on the total score. (2) In the Obsessive-Compulsive Drinking Scale (OCDS), there was a significance for time and group interaction between the G and P groups (P = .011) on the obsessive subscale. The total score of the OCDS showed significant time and group interactions between the G and P groups (P = .011). Our results showed that the extract of BSRGE containing a high level of GABA significantly reduced alcohol cravings in Korean social drinkers.

Intranasal as needed naloxone in the treatment of gambling disorder: A randomised controlled trial

BACKGROUND

Gambling disorder (GD) is a global phenomenon affecting millions of people. GD can result in severe social and financial difficulties and efficacious treatments are warranted. Psychosocial treatments form the basis of treatment. Opioid antagonists (OAs) have however shown promise in previous studies. In a recent imaging study intranasal naloxone was found to rapidly and fully occupy brain μ-opioid receptors. This trial investigates the effect and safety of as needed naloxone in the treatment of gambling disorder.

METHODS

This was a 12-week double blind, randomised control trial comparing intranasal naloxone to placebo. The primary endpoint was gambling urge measured by the Gambling symptom Assessment Scale (G-SAS). Secondary outcome measures were gambling severity measures (PGSI) as well as quality of life (WHO:EUROHIS-8), alcohol consumption (AUDIT), depression (MARDS) and internet use (IDS-9SF). In addition, safety of treatment was assessed. Both treatment groups received psychosocial support.

RESULTS

126 participants were randomised to treatment groups in a 1:1 ratio. 106 patients completed the study. Gambling urge (GSAS) and other gambling related measured improved in both groups, but no statistically significant difference could be found. Intranasal naloxone was well tolerated, no subjects discontinued the study due to adverse events. No serious adverse drug reactions were observed.

CONCLUSIONS

This study found no difference between the as-needed administration of intranasal naloxone and placebo in reducing gambling urge in persons with GD. Intranasal naloxone was safe and well tolerated.

Graph theory analysis of whole brain functional connectivity to assess disturbances associated with suicide attempts in bipolar disorder

Brain targets to lower the high risk of suicide in Bipolar Disorder (BD) are needed. Neuroimaging studies employing analyses dependent on regional assumptions could miss hubs of dysfunction critical to the pathophysiology of suicide behaviors and their prevention. This study applied intrinsic connectivity distribution (ICD), a whole brain graph-theoretical approach, to identify hubs of functional connectivity (FC) disturbances associated with suicide attempts in BD. ICD, from functional magnetic resonance imaging data acquired while performing a task involving implicit emotion regulation processes important in BD and suicide behaviors, was compared across 40 adults with BD with prior suicide attempts (SAs), 49 with BD with no prior attempts (NSAs) and 51 healthy volunteers (HVs). Areas of significant group differences were used as seeds to identify regional FC differences and explore associations with suicide risk-related measures. ICD was significantly lower in SAs than in NSAs and HVs in bilateral ventromedial prefrontal cortex (vmPFC) and right anterior insula (RaIns). Seed connectivity revealed altered FC from vmPFC to bilateral anteromedial orbitofrontal cortex, left ventrolateral PFC (vlPFC) and cerebellum, and from RaIns to right vlPFC and temporopolar cortices. VmPFC and RaIns ICD were negatively associated with suicidal ideation severity, and vmPFC ICD with hopelessness and attempt lethality severity. The findings suggest that SAs with BD have vmPFC and RaIns hubs of dysfunction associated with altered FC to other ventral frontal, temporopolar and cerebellar cortices, and with suicidal ideation, hopelessness, and attempt lethality. These hubs may be targets for novel therapeutics to reduce suicide risk in BD.

The Influence of Cross-Fostering on Alcohol Consumption and Depressive-Like Behaviors in HA and LA Mice: The Role of the Endogenous Opioid System

The development of alcohol dependence and depression is determined by various genetic and environmental factors. In the presented study, we used high analgesia (HA) and low analgesia (LA) mouse lines, characterized by different endogenous opioid system activity and divergent blood–brain barrier permeability, to determine the influence of cross-fostering of these lines raised by surrogate mothers on ethanol consumption and development of depressive-like behaviors. We also investigated ethanol drinking by biological parents or surrogate mothers. Furthermore, we investigated whether these parental changes would alter the effect of naloxone on ethanol intake and depressive-like behaviors in offspring. Our results reveal that cross-fostering of HA and LA raised by surrogate mothers has a greater impact on depressive-like behaviors than ethanol consumption. Ethanol intake by biological parents substantially affected depressive-like behaviors and ethanol consumption in offspring. Moreover, ethanol intake by biological parents or an adoptive mother modified the effect of naloxone on ethanol consumption and preference and depressive-like behaviors in the HA offspring only. Together, these results indicate that cross-fostering differentially affects the effect of naloxone on alcohol consumption and the development of depression.

Neurobiology of alcohol seeking behavior

Alcohol addiction is a chronic relapsing brain disease characterized by an impaired ability to stop or control alcohol use despite adverse consequences. A main challenge of addiction treatment is to prevent relapse, which occurs in more than >50% of newly abstinent patients with alcohol disorder within 3 months. In people suffering from alcohol addiction, stressful events, drug-associated cues and contexts, or re-exposure to a small amount of alcohol trigger a chain of behaviors that frequently culminates in relapse. In this review, we first present the preclinical models that were developed for the study of alcohol seeking behavior, namely the reinstatement model of alcohol relapse and compulsive alcohol seeking under a chained schedule of reinforcement. We then provide an overview of the neurobiological findings obtained using these animal models, focusing on the role of opioids systems, corticotropin-release hormone and neurokinins, followed by dopaminergic, glutamatergic, and GABAergic neurotransmissions in alcohol seeking behavior.

Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in “Heavy Drinking Smokers”

Aims

Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45–50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders.

Methods

We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions.

Results

The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders.

Conclusions

Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in ‘heavy drinking smokers.’

Drug Addiction: Hyperkatifeia/Negative Reinforcement as a Framework for Medications Development

Compulsive drug seeking that is associated with addiction is hypothesized to follow a heuristic framework that involves three stages (binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation) and three domains of dysfunction (incentive salience/pathologic habits, negative emotional states, and executive function, respectively) via changes in the basal ganglia, extended amygdala/habenula, and frontal cortex, respectively. This review focuses on neurochemical/neurocircuitry dysregulations that contribute to hyperkatifeia, defined as a greater intensity of negative emotional/motivational signs and symptoms during withdrawal from drugs of abuse in the withdrawal/negative affect stage of the addiction cycle. Hyperkatifeia provides an additional source of motivation for compulsive drug seeking via negative reinforcement. Negative reinforcement reflects an increase in the probability of a response to remove an aversive stimulus or drug seeking to remove hyperkatifeia that is augmented by genetic/epigenetic vulnerability, environmental trauma, and psychiatric comorbidity. Neurobiological targets for hyperkatifeia in addiction involve neurocircuitry of the extended amygdala and its connections via within-system neuroadaptations in dopamine, enkephalin/endorphin opioid peptide, and γ-aminobutyric acid/glutamate systems and between-system neuroadaptations in prostress corticotropin-releasing factor, norepinephrine, glucocorticoid, dynorphin, hypocretin, and neuroimmune systems and antistress neuropeptide Y, nociceptin, endocannabinoid, and oxytocin systems. Such neurochemical/neurocircuitry dysregulations are hypothesized to mediate a negative hedonic set point that gradually gains allostatic load and shifts from a homeostatic hedonic state to an allostatic hedonic state. Based on preclinical studies and translational studies to date, medications and behavioral therapies that reset brain stress, antistress, and emotional pain systems and return them to homeostasis would be promising new targets for medication development. SIGNIFICANCE STATEMENT: The focus of this review is on neurochemical/neurocircuitry dysregulations that contribute to hyperkatifeia, defined as a greater intensity of negative emotional/motivational signs and symptoms during withdrawal from drugs of abuse in the withdrawal/negative affect stage of the drug addiction cycle and a driving force for negative reinforcement in addiction. Medications and behavioral therapies that reverse hyperkatifeia by resetting brain stress, antistress, and emotional pain systems and returning them to homeostasis would be promising new targets for medication development.

Nicotine increases alcohol self-administration in male rats via a μ-opioid mechanism within the mesolimbic pathway

Background and Purpose

Alcohol and nicotine use disorders are commonly comorbid. Both alcohol and nicotine can activate opioid systems in reward‐related brain regions, leading to adaptive changes in opioid signalling upon chronic exposure. The potential role of these adaptations for comorbidity is presently unknown. Here, we examined the contribution of μ and κ‐opioid receptors to nicotine‐induced escalation of alcohol self‐administration in rats.

Experimental Approach

Chronic nicotine was tested on alcohol self‐administration and motivation to obtain alcohol. We then tested the effect of the κ antagonist CERC‐501 and the preferential μ receptor antagonist naltrexone on basal and nicotine‐escalated alcohol self‐administration. To probe μ or κ receptor adaptations, receptor binding and G‐protein coupling assays were performed in reward‐related brain regions. Finally, dopaminergic activity in response to alcohol was examined, using phosphorylation of DARPP‐32 in nucleus accumbens as a biomarker.

Key Results

Nicotine robustly induced escalation of alcohol self‐administration and motivation to obtain alcohol. This was blocked by naltrexone but not by CERC‐501. Escalation of alcohol self‐administration was associated with decreased DAMGO‐stimulated μ receptor signalling in the ventral tegmental area (VTA) and decreased pDARPP‐32 in the nucleus accumbens shell in response to alcohol.

Conclusions and Implications

Collectively, these results suggest that nicotine contributes to escalate alcohol self‐administration through a dysregulation of μ receptor activity in the VTA. These data imply that targeting μ rather than κ receptors may be the preferred pharmacotherapeutic approach for the treatment of alcohol use disorder when nicotine use contributes to alcohol consumption.

Pain-induced alterations in the dynorphinergic system within the mesocorticolimbic pathway: Implication for alcohol addiction

Latest studies have revealed that pain negatively impacts on reward processing and motivation leading to negative affective states and stress. These states not only reduce quality of life of patients by increasing the appearance of psychiatric comorbidities, but also have an important impact on vulnerability to drug abuse, including alcohol. In fact, clinical, epidemiological but also preclinical studies have revealed that the presence of pain is closely related to alcohol use disorders (AUDs). All this evidence suggests that pain is a factor that increases the risk of suffering AUD, predicting heavy drinking behavior and relapse drinking in those patients with a previous history of AUD. The negative consequences of chronic pain and its impact on stress and AUD are likely mediated by alterations in the central nervous system, especially in the stress and reward systems. Therefore, pain and stress impact on dopaminergic mesolimbic pathway can lead to an increase in drug abuse liability. In this mini review we analyze the interaction between pain, stress, and alcohol addiction, and how dynamic changes in the kappa opioid system might play a crucial role in the development of compulsive alcohol drinking in chronic pain patients.

Behavioral, neurobiological, and neurochemical mechanisms of ethanol self-administration: A translational review

Alcohol use disorder has multiple characteristics including excessive ethanol consumption, impaired control over drinking behaviors, craving and withdrawal symptoms, compulsive seeking behaviors, and is considered a chronic condition. Relapse is common. Determining the neurobiological targets of ethanol and the adaptations induced by chronic ethanol exposure is critical to understanding the clinical manifestation of alcohol use disorders, the mechanisms underlying the various features of the disorder, and for informing medication development. In the present review, we discuss ethanol's interactions with a variety of neurotransmitter systems, summarizing findings from preclinical and translational studies to highlight recent progress in the field. We then describe animal models of ethanol self-administration, emphasizing the value, limitations, and validity of commonly used models. Lastly, we summarize the behavioral changes induced by chronic ethanol self-administration, with an emphasis on cue-elicited behavior, the role of ethanol-related memories, and the emergence of habitual ethanol seeking behavior.

So Uncommon and so Singular, but Underexplored: An Updated Overview on Ethnobotanical Uses, Biological Properties and Phytoconstituents of Sardinian Endemic Plants

The last decades have recorded an increase of plant-based drug discovery processes. Indeed, natural products possess a superior chemical diversity as compared to synthetic ones, leading to a renewal in searching for new therapeutic agents from the plant kingdom. In particular, since the structural variety of natural compounds reflects the biodiversity of their source organisms, regions of the world with high biodiversity and endemism deserve particular interest. In this context, Sardinia Island (Italy), with 290 endemic taxa (12% of the total flora), is expected to provide unique and structurally diverse phytochemicals for drug development. Several research groups built up a large program dedicated to the analysis of Sardinian endemic species, highlighting their peculiar features, both in respect of phytochemical and biological profiles. On this basis, the aim of this review is to provide an up-to-date and comprehensive overview on ethnobotanical uses, biological properties and phytoconstituents of Sardinian endemic plants in order to support their beneficial potential and to provide input for future investigations. We documented 152 articles published from 1965 to June 2020 in which a broad range of biological activities and the identification of previously undescribed compounds have been reported, supporting their great value as sources of therapeutic agents.

[Alcohol dependence and opioid receptor -Pharmacological profile of nalmefene]

Alcohol dependence is one of the psychiatric disorders affecting over 1 million people in Japan. Mesolimbic dopamine neuron projecting from ventral tegmental area to nucleus accumbens (Reward system) plays important roles in alcohol dependence including other dependence. Accumulating evidence indicates that the endogenous opioid system regulate this reward system. That is, alcohol stimulates the release of endogenous opioid peptides such as β-endorphin and dynorphin in the brain. β-endorphin activates μ-opioid receptor leading to euphoric mood and positive reinforcement, while dynorphin activates κ-opioid receptor leading to dysphoric mood and negative reinforcement. These euphoric/dysphoric mood and reinforcement effects via endogenous opioid systems are suggested to be implicated in repeated alcohol intake in patients with alcohol dependence. Nalmefene acts as an antagonist at μ- and δ-opioid receptor and a partial agonist at κ-opioid receptor. Preclinical studies have shown that nalmefene reduced the alcohol intake in alcohol preference rats. In clinical trials, as-needed use of nalmefene with psychosocial support reduced the number of heavy-drinking days and total alcohol consumption. These results suggest that nalmefene modulates the alcohol-induced euphoric/dysphoric mood via opioid system and thereby contribute to reduction in alcohol consumption in patients with alcohol dependence. Here, we summarize the implications of opioid system in alcohol dependence and pharmacological profiles of nalmefene in preclinical and clinical studies.

Role of the treatment environment in the effects of aripiprazole on ethanol-induced behavioral sensitization and conditioned place preference in female mice

BACKGROUND

Evidence suggests that aripiprazole, a partial dopamine D2 and serotonin 5-HT1A receptor agonist and 5-HT2A receptor antagonist, show significant efficacy in reducing alcohol use. We have previously demonstrated that treatment with aripiprazole blocked the reinstatement of cocaine-induced behavioral sensitization in a context-dependent manner, suggesting that the treatment environment may modulate the therapeutic effects of aripiprazole. The present study aimed to evaluate the effects of treatment with aripiprazole on ethanol-induced behavioral sensitization and conditioned place preference in female mice, and the role of the treatment environment in those effects.

METHODS

Adult female mice were either sensitized with ethanol injections in the open-field apparatus, or conditioned with ethanol in the conditioned place preference (CPP) apparatus. Animals were then treated with vehicle or 0.1 mg/kg aripiprazole paired to the test environment (open-field or CPP apparatus) or not (home-cage treatments) for 4 alternate days, and the subsequent expression of behavioral sensitization or CPP to ethanol was evaluated during or following an ethanol re-exposure, respectively.

RESULTS

Repeated treatment with aripiprazole attenuated the expression of ethanol-induced behavioral sensitization regardless of the treatment environment. Treatment with aripiprazole was only effective at preventing the reinstatement of ethanol-induced CPP when paired with the ethanol-associated environment, but not when administered in the home-cage.

CONCLUSIONS

The present findings corroborate previous studies suggesting the effectiveness of aripiprazole for the treatment of alcohol use disorder. Our results also point to an important role of the treatment environment in the therapeutic effects of aripiprazole in rodent models of ethanol abuse.

Targeting liver aldehyde dehydrogenase-2 prevents heavy but not moderate alcohol drinking

Aldehyde dehydrogenase 2 (ALDH2), a key enzyme for detoxification the ethanol metabolite acetaldehyde, is recognized as a promising therapeutic target to treat alcohol use disorders (AUDs). Disulfiram, a potent ALDH2 inhibitor, is an approved drug for the treatment of AUD but has clinical limitations due to its side effects. This study aims to elucidate the relative contribution of different organs in acetaldehyde clearance through ALDH2 by using global- (Aldh2 ^-/-) and tissue-specific Aldh2-deficient mice, and to examine whether liver-specific ALDH2 inhibition can prevent alcohol-seeking behavior. Aldh2 ^-/- mice showed markedly higher acetaldehyde concentrations than wild-type (WT) mice after acute ethanol gavage. Acetaldehyde levels in hepatocyte-specific Aldh2 knockout (Aldh2 ^Hep-/-) mice were significantly higher than those in WT mice post gavage, but did not reach the levels observed in Aldh2 ^-/- mice. Energy expenditure and motility were dramatically dampened in Aldh2 ^-/- mice, but moderately decreased in Aldh2 ^Hep-/- mice compared to controls. In the 2-bottle paradigm and the drinking-in-the-dark model, Aldh2 ^-/- mice drank negligible volumes from ethanol-containing bottles, whereas Aldh2 ^Hep-/- mice showed reduced alcohol preference at high but not low alcohol concentrations. Glial cell- or neuron-specific Aldh2 deficiency did not affect voluntary alcohol consumption. Finally, specific liver Aldh2 knockdown via injection of shAldh2 markedly decreased alcohol preference. In conclusion, although the liver is the major organ responsible for acetaldehyde metabolism, a cumulative effect of ALDH2 from other organs likely also contributes to systemic acetaldehyde clearance. Liver-targeted ALDH2 inhibition can decrease heavy drinking without affecting moderate drinking, providing molecular basis for hepatic ALDH2 targeting/editing for the treatment of AUD.

Sleep and the Pharmacotherapy of Alcohol Use Disorder: Unfortunate Bedfellows. A Systematic Review With Meta-Analysis

Background: Sleep disorders are commonly associated with acute and chronic use of alcohol and with abstinence. To date, there are four approved drugs to treat alcohol use disorder (AUD): disulfiram, acamprosate, naltrexone, and nalmefene. These AUD therapies reduce the craving and risk of relapse into heavy drinking, but little is known about their effect on sleep. As recent evidences indicate a crucial role of sleep disorders in AUD, claiming that sleep problems may trigger alcohol abuse and relapses, it is fundamental to clarify the impact of those drugs on the sleep quality of AUD patients. This systematic review aims to answer the question: how does the pharmacotherapy for AUD affect sleep? Methods: We searched PubMed, Embase, CINAHL Plus, Cochrane, and Scopus using sleep- and AUD pharmacotherapy-related keywords. The articles included were appraised using the CASP checklists, and the risk of bias was assessed following the Cochrane risk-of-bias assessment tool. Finally, we pooled sleep outcomes in a meta-analysis to measure the overall effect. Results and Conclusion: We included 26 studies: only three studies focused on sleep as a main outcome, two with polysomnography (objective measurement), and one with subjective self-reported sleep, while all the other studies reported sleep problems among the adverse effects (subjective report). The only study available on disulfiram showed reduced REM sleep. Acamprosate showed no/little effect on self-reported sleep but improved sleep continuity and architecture measured by polysomnography. The two opioidergic drugs naltrexone and nalmefene had mainly detrimental effect on sleep, giving increased insomnia and/or somnolence compared with placebo, although not always significant. The meta-analysis confirmed significantly increased somnolence and insomnia in the naltrexone group, compared with the placebo. Overall, the currently available evidences show more sleep problems with the opioidergic drugs (especially naltrexone), while acamprosate seems to be well tolerated or even beneficial. Acamprosate might be a more suitable choice when patients with AUD report sleep problems. Due to the paucity of information available, and with the majority of results being subjective, more research on this topic is needed to further inform the clinical practice, ideally with more objective measurements such as polysomnography.

Design, Synthesis, and Biological Evaluation of the Third Generation 17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)carboxamido]morphinan (NAP) Derivatives as μ/κ Opioid Receptor Dual Selective Ligands

μ opioid receptor (MOR) agonists have been widely applied for treating moderate to severe pain. However, numerous adverse effects have been associated with their application, including opioid-induced constipation (OIC), respiratory depression, and addiction. On the basis of previous work in our laboratory, NAP, a 6β- N-4'-pyridyl substituted naltrexamine derivative, was identified as a peripheral MOR antagonist that may be used to treat OIC. To further explore its structure-activity relationship, a new series of NAP derivatives were designed, synthesized, and biologically evaluated. Among these derivatives, NFP and NYP significantly antagonized the antinociception effect of morphine. Whereas NAP acted mainly peripherally, its derivatives NFP and NYP actually can act centrally. Furthermore, NFP produced significantly lesser withdrawal symptoms than naloxone at similar doses. These results suggest that NFP has the potential to be a lead compound to treat opioid abuse and addiction.

A Phenomenological Contribution to Substance Misuse Treatment: Principles for Person-Centered Care

Despite the significant need for coordinated approaches to the treatment of substance misuse worldwide, there are still major gaps in both the provision of services and in the development of a theoretically unified approach to care. We suggest that a phenomenological approach to care can provide comprehensive, theoretically grounded guidelines that coordinate and help choose between a range of interventions while respecting the values of the patient and other stakeholders. The aim of this paper is to present a framework for a person-centered approach to substance misuse care, based on general principles of phenomenology. In particular, we emphasize a dialectic conception of phenomenological care, one that considers the various tensions and conflicts of human life, and the ways these are managed by individuals. Two dialectics are presented here: the dialectic of anthropological proportions, involved in the existential situation of the substance misuser, and the dialect of decision, which is essential to all approaches to the treatment of substance misuse. The dialectic of proportions in the substance misuser's experience involves hyperpresentification, the tendency to emphasize the present moment to the relative exclusion or reduction of the past and future considerations, and feelings of plenitude, an oversimplification of experience that ignores the complexity present in every situation. Interventions should reflect a dialectic of decision, which allows the clinician and patient to choose pathways that promote movement and expand the limitations of hyperpresentification and plenitude. This phenomenological framework, we suggest, permits a collaborative and values-based approach to comprehensive clinical decision-making.

Mu opioid receptors in GABAergic neurons of the forebrain promote alcohol reward and drinking

Mu opioid receptors (MORs) are widely distributed throughout brain reward circuits and their role in drug and social reward is well established. Substantial evidence has implicated MOR and the endogenous opioid system in alcohol reward, but circuit mechanisms of MOR-mediated alcohol reward and intake behavior remain elusive, and have not been investigated by genetic approaches. We recently created conditional knockout (KO) mice targeting the Oprm1 gene in GABAergic forebrain neurons. These mice (Dlx-MOR KO) show a major MOR deletion in the striatum, whereas receptors in midbrain (including the Ventral Tegmental Area or VTA) and hindbrain are intact. Here, we compared alcohol-drinking behavior and rewarding effects in total (MOR KO) and conditional KO mice. Concordant with our previous work, MOR KO mice drank less alcohol in continuous and intermittent two-bottle choice protocols. Remarkably, Dlx-MOR KO mice showed reduced drinking similar to MOR KO mice, demonstrating that MOR in the forebrain is responsible for the observed phenotype. Further, alcohol-induced conditioned place preference was detected in control but not MOR KO mice, indicating that MOR is essential for alcohol reward and again, Dlx-MOR KO recapitulated the MOR KO phenotype. Taste preference and blood alcohol levels were otherwise unchanged in mutant lines. Together, our data demonstrate that MOR expressed in forebrain GABAergic neurons is essential for alcohol reward-driven behaviors, including drinking and place conditioning. Challenging the prevailing VTA-centric hypothesis, this study reveals another mechanism of MOR-mediated alcohol reward and consumption, which does not necessarily require local VTA MORs but rather engages striatal MOR-dependent mechanisms.

Methylation Products of 6β- N-Heterocyclic Substituted Naltrexamine Derivatives as Potential Peripheral Opioid Receptor Modulators

Two 6β- N-heterocyclic naltrexamine derivatives, NAP and NMP, have been identified as peripherally selective mu opioid receptor (MOR) antagonists. To further enhance the peripheral selectivity of both compounds, the 17-amino group and the nitrogen atom of the pyridine ring in both NAP and NMP were methylated to obtain dMNAP and dMNMP, respectively. Compared with NAP and NMP, the binding affinities of dMNAP and dMNMP shifted to MOR and KOR (kappa opioid receptor) dual selective and they acted as moderate efficacy partial agonists. The results from radioligand binding studies were further confirmed by molecular docking studies. In vivo studies demonstrated that dMNAP and dMNMP did not produce antinociception nor did they antagonize morphine's antinociceptive activity, indicating that these compounds did not act on the central nervous system. Meanwhile, both dMNAP and dMNMP significantly slowed down fecal excretion, which indicated that they were peripherally acting opioid receptor agonists. All together, these results suggested that dMNAP and dMNMP acted as peripheral mu/kappa opioid receptor modulators and may be applicable in the treatment of diarrhea in patients with bowel dysfunction.

Opioid Antagonists for Pharmacological Treatment of Gambling Disorder: Are they Relevant?

Background:

To date, no drugs have been approved for gambling disorder. Numerous publications have described the value of opioid antagonists. Indeed, the mesocorticolimbic dopaminergic pathway has been suggested as the underlying cause of reward-seeking behaviour, and it is modulated by the opioid system.

Objective:

This study aims to evaluate the relevance of opioid antagonists for treating GD.

Method:

A systematic literature review was conducted. A search of the PubMed electronic database, PsycINFO and the Cochrane Systematic Review Database without any limits was performed.

Results:

There is little information concerning the effects of opioid antagonists on GD. The total search with “nalmefene and gambling” without any limits revealed only 11 articles. The search with “naltrexone and gambling” without any limits gener-ated 47 articles. Nevertheless, the best available data support the use of opioid antagonists, particularly in individuals with a history of alcohol use disorder or strong gambling urges.

Conclusion:

Future trials are still needed. Indeed, opioid antagonists effectiveness has been investigated in only a limited number of patients, clinical trials do not reflect the heterogeneity of GD and there is little knowledge of the predictive factors of response to treatments. Moreover, differential affinity to nalmefene for kappa receptors may be associated with a particular effect in a yet to be defined addiction phenotype. Head to head comparisons between naltrexone and nalmefene would be helpful in combining other medication or psychotherapy. The identification of subgroups of patients that are more likely to benefit from opioid antagonists should be a goal

A case report SPECT study and theoretical rationale for the sequential administration of ibogaine and 5-MeO-DMT in the treatment of alcohol use disorder

Ibogaine is a plant-derived alkaloid and dissociative psychedelic that demonstrates anti-addictive properties with several substances of abuse, including alcohol. 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a naturally occurring psychedelic known to occasion potent mystical-type experiences and also demonstrates anti-addictive properties. The potential therapeutic effects of both compounds in treating alcohol use disorder require further investigation and there are no published human neuroimaging findings of either treatment to date. We present the case of a 31-year-old male military veteran with moderate alcohol use disorder who sought treatment at an inpatient clinic in Mexico that utilized a sequential protocol with ibogaine hydrochloride (1550mg, 17.9mg/kg) on day 1, followed by vaporized 5-MeO-DMT (bufotoxin source 50mg, estimated 5-MeO-DMT content, 5-7mg) on day 3. The patient received SPECT neuroimaging that included a resting-state protocol before, and 3 days after completion of the program. During the patient's ibogaine treatment, he experienced dream-like visions that included content pertaining to his alcohol use and resolution of past developmental traumas. He described his treatment with 5-MeO-DMT as a peak transformational and spiritual breakthrough. On post-treatment SPECT neuroimaging, increases in brain perfusion were noted in bilateral caudate nuclei, left putamen, right insula, as well as temporal, occipital, and cerebellar regions compared to the patient's baseline scan. The patient reported improvement in mood, cessation of alcohol use, and reduced cravings at 5 days post-treatment, effects which were sustained at 1 month, with a partial return to mild alcohol use at 2 months. In this case, serial administration of ibogaine and 5-MeO-DMT resulted in increased perfusion in multiple brain regions broadly associated with alcohol use disorders and known pharmacology of both compounds, which coincided with a short-term therapeutic outcome. We present theoretical considerations regarding the potential of both psychedelic medicines in treating alcohol use disorders in the context of these isolated findings, and areas for future investigation.

The OPRM1 A118G polymorphism: converging evidence against associations with alcohol sensitivity and consumption

The endogenous opioid system may be involved in the development and maintenance of alcohol use disorder (AUD) and is a target for existing AUD pharmacotherapies. A functional polymorphism of the mu-opioid receptor gene (OPRM1 A118G, rs1799971) may alter the risk of developing AUD. Human laboratory studies have demonstrated that minor allele carriers self-administer more alcohol, show greater sensitivity to alcohol's effects, and exhibit increased alcohol-induced dopamine release. On the other hand, large genome-wide association studies and meta-analyses of candidate gene studies have not found an association between this genotype and alcohol dependence diagnosis. Given this discrepancy, the present study sought to verify whether OPRM1 A118G was associated with alcohol self-administration, subjective response to alcohol, and craving in a sample of 106 social drinkers of European ancestry who completed an intravenous alcohol self-administration session. We found no relationship between OPRM1 rs1799971 genotype and subjective response to alcohol or craving. OPRM1 genotype was not associated with total alcohol exposure or likelihood of attaining a binge-level exposure (80 mg%) during the intravenous alcohol self-administration session. Analysis of 90-day Timeline Followback interview data in a larger sample of 965 participants of European ancestry found no relationship between OPRM1 genotype and alcohol consumption in either alcohol dependent or non-dependent participants. These findings suggest that there may not be an association between OPRM1 rs1799971 genotype and alcohol consumption or sensitivity in individuals of European ancestry.

Delta-opioid receptor antagonism leads to excessive ethanol consumption in mice with enhanced activity of the endogenous opioid system

The opioid system modulates the central reinforcing effects of ethanol and participates in the etiology of addiction. However, the pharmacotherapy of ethanol dependence targeted on the opioid system is little effective and varies due to individual patients' sensitivity. In the present study, we used two mouse lines with high (HA) and low (LA) activity of the endogenous opioid system to analyze the effect of opioid receptor blockade on ethanol drinking behavior. We found that LA and HA lines characterized by divergent magnitudes of swim stress-induced analgesia also differ in ethanol intake and preference. Downregulation of the opioid system in LA mice was associated with increased ethanol consumption. Treatment with a non-selective opioid receptor antagonist (naloxone) had no effect on ethanol intake in this line. Surprisingly, in HA mice, the blockage of opioid receptors led to excessive ethanol consumption. Moreover, naloxone selectively induced high levels of anxiety- and depressive-like behaviors in HA mice which was attenuated by ethanol. With the use of specific opioid receptor antagonists we showed that the naloxone-induced increase in ethanol drinking in HA mice is mediated mainly by δ and to a lower extent by μ opioid receptors. The effect of δ-opioid receptor antagonism was abolished in HA mice carrying a C320T transition in the δ-opioid receptor gene (EU446125.1), which impairs this receptor's function. Our results indicate that high activity of the opioid system plays a protective role against ethanol dependence. Therefore, its blockage with opioid receptor antagonists may lead to a profound increase in ethanol consumption.

Relationship between prescribed psychotropic medications and co-ingested alcohol in intentional self-poisonings

BackgroundAcute alcohol consumption is a major risk factor for suicide, therefore investigating factors associated with alcohol-related self-harm warrant attention.AimsTo investigate the influence of prescribed psychotropic medications on the odds of co-ingesting alcohol preceding or during intentional efforts to self-poison.MethodA cross-sectional analysis of consecutive hospital presentations following intentional self-poisoning was conducted. A total of 7270 patients (4363 women) aged 18-96 were included.ResultsThe odds of alcohol co-ingestion were increased in those not prescribed any medication (odds ratio (OR) = 1.27, 99% CI 1.10-1.46, P<0.001) and in impulsive self-poisonings (OR = 1.39, 99% CI 1.11-1.74, P<0.001). Odds were decreased in those prescribed anticonvulsants (OR = 0.69, 99% CI 0.51-0.93), antipsychotics (OR = 0.55, 99% CI 0.45-0.66) and antidepressants (OR = 0.87, 99% CI 0.77-0.99).ConclusionsFindings indicate that being medicated for a psychiatric illness may reduce the likelihood of alcohol consumption during times of acute distress, hence perhaps may reduce the risk of intentional self-poisoning.

Guidelines for biological treatment of substance use and related disorders, part 1: Alcoholism, first revision

These practice guidelines for the biological treatment of alcohol use disorders are an update of the first edition, published in 2008, which was developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBP). For this 2016 revision, we performed a systematic review (MEDLINE/PUBMED database, Cochrane Library) of all available publications pertaining to the biological treatment of alcoholism and extracted data from national guidelines. The Task Force evaluated the identified literature with respect to the strength of evidence for the efficacy of each medication and subsequently categorised it into six levels of evidence (A-F) and five levels of recommendation (1-5). Thus, the current guidelines provide a clinically and scientifically relevant, evidence-based update of our earlier recommendations. These guidelines are intended for use by clinicians and practitioners who evaluate and treat people with alcohol use disorders and are primarily concerned with the biological treatment of adults with such disorders.

Treatment-refractory substance use disorder: Focus on alcohol, opioids, and cocaine

Substance use disorders are common, but only a small minority of patients receive adequate treatment. Although psychosocial therapies are effective, relapse is common. This review focusses on novel pharmacological and other treatments for patients with alcohol, opioid, or cocaine use disorders who do not respond to conventional treatments. Disulfiram, acamprosate, and the opioid antagonist naltrexone have been approved for the treatment of alcoholism. A novel, "as needed" approach is the use of the mu-opioid antagonist and partial kappa agonist nalmefene to reduce alcohol consumption. Other novel pharmacological approaches include the GABA-B receptor agonist baclofen, anticonvulsants such as topiramate and gabapentin, the partial nicotine receptor agonist varenicline, and other drugs. For opioid dependence, opioid agonist therapy with methadone or buprenorphine is the first-line treatment option. Other options include oral or depot naltrexone, morphine sulfate, depot or implant formulations, and heroin (diacetylmorphine) in treatment-refractory patients. To date, no pharmacological treatment has been approved for cocaine addiction; however, 3 potential pharmacological treatments are being studied, disulfiram, methylphenidate, and modafinil. Pharmacogenetic approaches may help to optimize treatment response in otherwise treatment-refractory patients and to identify which patients are more likely to respond to treatment, and neuromodulation techniques such as repeated transcranial magnetic stimulation and deep brain stimulation also may play a role in the treatment of substance use disorders. Although no magic bullet is in sight for treatment-refractory patients, some novel medications and brain stimulation techniques have the potential to enrich treatment options at least for some patients.

Increased steroid hormone dehydroepiandrosterone and pregnenolone levels in post-mortem brain samples of alcoholics

Intra-tissue levels of steroid hormones (e.g., dehydroepiandrosterone [DHEA], pregnenolone [PREGN], and testosterone [T]) may influence the pathological changes seen in neurotransmitter systems of alcoholic brains. Our aim was to compare levels of these steroid hormones between the post-mortem brain samples of alcoholics and non-alcoholic controls. We studied steroid levels with quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) in post-mortem brain samples of alcoholics (N = 14) and non-alcoholic controls (N = 10). Significant differences were observed between study groups in DHEA and PREGN levels (p values 0.0056 and 0.019, respectively), but not in T levels. Differences between the study groups were most prominent in the nucleus accumbens (NAC), anterior cingulate cortex (ACC), and anterior insula (AINS). DHEA levels were increased in most alcoholic subjects compared to controls. However, only a subgroup of alcoholics showed increased PREGN levels. Negative Spearman correlations between tissue levels of PREGN and previous reports of [(3)H]naloxone binding to μ-opioid receptors were observed in the AINS, ACC, NAC, and frontal cortex (R values between -0.6 and -0.8; p values ≤ 0.002), suggesting an association between the opioid system and brain PREGN levels. Although preliminary, and from relatively small diagnostic groups, these results show significantly increased levels of DHEA and PREGN in the brains of alcoholics, and could be associated with the pathology of alcoholism.

Sodium oxybate plus nalmefene for the treatment of alcohol use disorder: A case series

The treatment of alcohol use disorder still remains a challenge. The efficacy of the combined pharmacological treatment for alcohol use disorder has been widely investigated with controversial results. The aim of our case series was to investigate the effect of nalmefene in patients not responding to sodium oxybate therapy. We describe seven cases of consecutive patients affected by alcohol use disorder, and treated with sodium oxybate (50 mg/kg per day) who did not achieve complete alcohol abstinence after at least one month of pharmacological treatment. Then, in partial- and non-responder patients to sodium oxybate treatment, administration of nalmefene, 18 mg as needed, was commenced. Our data show that, during the first month of the combined treatment of sodium oxybate plus nalmefene, patients were able to achieve alcohol abstinence (two patients), to suppress (five cases) or reduce (two patients) episodes of heavy drinking days, and to suppress the onset of craving for sodium oxybate (one patient). Likely, nalmefene may act in modulating the excessive reward effect of sodium oxybate, which may be responsible for the persistence of alcohol intake and for the onset of craving for sodium oxybate. However, controlled clinical trials to confirm the safety and efficacy of sodium oxybate plus nalmefene in treating alcohol use disorder are warranted.

Nalmefene for the treatment of alcohol use disorders: recent data and clinical potential

INTRODUCTION

Few pharmacotherapies are available for alcoholism. Numerous studies indicate the involvement of the opioid-endorphin system in mediating the reinforcing effects of alcohol via dopaminergic neurons. The opioid antagonist naltrexone was found to be effective in alcohol treatment, and the European Medicines Agency has now approved the mu-opioid antagonist und partial kappa agonist nalmefene.

AREAS COVERED

This article presents background information on the chemistry of nalmefene and pre-clinical and clinical findings. The three relevant Phase III studies, all of which followed a harm-reduction, "as needed" approach and found reduced alcohol consumption with nalmefene 18 (20) mg, are discussed in detail.

EXPERT OPINION

The integration of the "as needed" approach into conventional psychosocial alcohol therapies may be challenging but offers the opportunity to reach otherwise not treated patients. Nalmefene is the first medication to be approved specifically in this indication and seems to be most suitable for patients with alcohol misuse or a rather low physical dependence on alcohol who do not require immediate detoxification or inpatient treatment. Although a categorical distinction between patients who want to stop heavy drinking or drinking at all over time may be somewhat hypothetical, nalmefene offers new treatment options to patients with alcohol use disorder.

Possible role of a dysregulation of the endogenous opioid system in antisocial personality disorder

Around half the inmates in prison institutions have antisocial personality disorder (ASPD). A recent theory has proposed that a dysfunction of the endogenous opioid system (EOS) underlies the neurobiology of borderline personality disorder (BPD). In the present theoretical paper, based on a comprehensive database and hand search of the relevant literature, this hypothesis is extended to ASPD, which may be the predominant expression of EOS dysfunction in men, while the same pathology underlies BPD in women. According to evidence from human and animal studies, the problematic behaviours of persons with antisocial, callous, or psychopathic traits may be seen as desperate, unconscious attempts to stimulate their deficient EOS, which plays a key role in brain reward circuits. If the needs of this system are not being met, the affected persons experience dysphoric mood, discomfort, or irritability, and strive to increase binding of endogenous opioids to receptors by using the rewarding effects of aggression by exertion of physical or manipulative power on others, by abusing alcohol or substances that have the reward system as target, by creating an "endorphin rush" by self-harm, by increasing the frequency of their sexual contacts, or by impulsive actions and sensation seeking. Symptoms associated with ASPD can be treated with opioid antagonists like naltrexone, naloxone, or nalmefene.

Kappa opioid receptor signaling in the brain: Circuitry and implications for treatment

Kappa opioid receptors (KORs) in the central nervous system have been known to be important regulators of a variety of psychiatry illnesses, including anxiety and addiction, but their precise involvement in these disorders is complex and has yet to be fully elucidated. Here, we briefly review the pharmacology of KORs in the brain, including KOR's involvement in anxiety, depression, and drug addiction. We also review the known neuronal circuitry impacted by KOR signaling, and interactions with corticotrophin-releasing factor (CRF), another key peptide in anxiety-related illnesses, as well as the role of glucocorticoids. We suggest that KORs are a promising therapeutic target for a host of neuropsychiatric conditions.

Dual motor responses elicited by ethanol in the posterior VTA: Consequences of the blockade of μ-opioid receptors

A recent hypothesis, based on electrophysiological and behavioural findings, suggests that ethanol simultaneously exerts opposed effects on the activity of dopamine (DA) neurons in the ventral tegmental area (VTA) through two parallel mechanisms, one promoting and the other reducing the GABA release onto VTA DA neurons. In this sense, the activating effects are mediated by salsolinol, a metabolite of ethanol, acting on the μ-opioid receptors (MORs) located in VTA GABA neurons. The inhibitory effects are, however, triggered by the non-metabolized fraction of ethanol which would cause the GABAA receptors-mediated inhibition of VTA DA neurons. Since both trends tend to offset each other, only the use of appropriate pharmacological tools allows analysis of this phenomenon in depth. Herein, we present new behavioural findings supporting this hypothesis. Motor activity was evaluated in rats after intra-VTA administration of ethanol 35 nmol, an apparently ineffective dose, 24 h after the irreversible blockade of MORs in the VTA with β-FNA. Our results showed that this pre-treatment turned the initially ineffective ethanol dose into a depressant one, confirming that the activating effect of ethanol can be selectively suppressed without affecting the depressant effects mediated by the non-biotransformed fraction of ethanol.