Alcohol self-administration, craving and HPA-axis activity: an intriguing relationship

Possible Role of CRF-Hcrt Interaction in the Infralimbic Cortex in the Emergence and Maintenance of Compulsive Alcohol-Seeking Behavior

Alcohol use disorder (AUD) is a chronic, relapsing disorder that is characterized by the compulsive use of alcohol despite numerous health, social, and economic consequences. Initially, the use of alcohol is driven by positive reinforcement. Over time, however, alcohol use can take on a compulsive quality that is driven by the desire to avoid the negative consequences of abstinence, including negative affect and heightened stress/anxiety. This transition from positive reinforcement- to negative reinforcement-driven consumption involves the corticotropin-releasing factor (CRF) system, although mounting evidence now suggests that the CRF system interacts with other neural systems to ultimately produce behaviors that are symptomatic of compulsive alcohol use, such as the hypocretin (Hcrt) system. Hypocretins are produced exclusively in the hypothalamus, but Hcrt neurons project widely throughout the brain and reach regions that perform regulatory functions for numerous behavioral and physiological responses-including the infralimbic cortex (IL) of the medial prefrontal cortex (mPFC). Although the entire mPFC undergoes neuroadaptive changes following prolonged alcohol exposure, the IL appears to undergo more robust changes compared with other mPFC substructures. Evidence to date suggests that the IL is likely involved in EtOH-seeking behavior, but ambiguities with respect to the specific role of the IL in this regard make it difficult to draw definitive conclusions. Furthermore, the manner in which CRF interacts with Hcrt in this region as it pertains to alcohol-seeking behavior is largely unknown, although immunohistochemical and electrophysiological experiments have shown that CRF and Hcrt directly interact in the mPFC, suggesting that the interaction between CRF and Hcrt in the IL may be critically important for the development and subsequent maintenance of compulsive alcohol seeking. This review aims to consolidate recent literature regarding the role of the IL in alcohol-seeking behavior and to discuss evidence that supports a functional interaction between Hcrt and CRF in the IL.

Neuroendocrine response to GABA-B receptor agonism in alcohol-dependent individuals: Results from a combined outpatient and human laboratory experiment

Gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the nervous system, plays an important role in biobehavioral processes that regulate alcohol seeking, food intake, and stress response. The metabotropic GABA-B receptor has been investigated as a potential therapeutic target for alcohol use disorder, by using orthosteric agonists (e.g., baclofen) and positive allosteric modulators. Whether and how pharmacological manipulation of the GABA-B receptor, in combination with alcohol intake, may affect feeding- and stress-related neuroendocrine pathways remains unknown. In the present randomized, double-blind, placebo-controlled study, thirty-four alcohol-dependent individuals received baclofen (30 mg/day) or placebo in a naturalistic outpatient setting for one week, and then performed a controlled laboratory experiment which included alcohol cue-reactivity, fixed-dose priming, and self-administration procedures. Blood samples were collected, and the following neuroendocrine markers were measured: ghrelin, leptin, amylin, glucagon-like peptide-1 (GLP-1), insulin, prolactin, thyroid-stimulating hormone, growth hormone, cortisol, and adrenocorticotropic hormone (ACTH). During the outpatient phase, baclofen significantly increased blood concentrations of acyl-ghrelin (p = 0.01), leptin (p = 0.01), amylin (p = 0.004), and GLP-1 (p = 0.02). Significant drug × time-point interaction effects for amylin (p = 0.001) and insulin (p = 0.03), and trend-level interaction effects for GLP-1 (p = 0.06) and ACTH (p = 0.10) were found during the laboratory experiment. Baclofen, compared to placebo, had no effect on alcohol drinking in this study (p's ≥ 0.05). Together with previous studies, these findings shed light on the role of the GABAergic system and GABA-B receptors in the shared neurobiology of alcohol-, feeding-, and stress-related behaviors.

Oxytocin and Naltrexone Successfully Treat Hypothalamic Obesity in a Boy Post-Craniopharyngioma Resection

CONTEXT

Hypothalamic obesity, a treatment-resistant condition common to survivors of craniopharyngioma (CP), is strongly associated with a poor quality of life in this population. Oxytocin (OT), a hypothalamic neuropeptide, has been shown to play a role in the regulation of energy balance and to have anorexigenic effects in animal studies. Naltrexone (NAL), an opiate antagonist, has been shown to deter hedonic eating and to potentiate OT's effects.

DESIGN

In this parent-observed study, we tested the administration of intranasal OT for 10 weeks (phase 1), followed by a combination of intranasal OT and NAL for 38 weeks (phase 2) in a 13-year-old male with confirmed hypothalamic obesity and hyperphagia post-CP resection. Treatment resulted in 1) reduction in body mass index (BMI) z score from 1.77 to 1.49 over 10 weeks during phase 1; 2) reduction in BMI z score from 1.49 to 0.82 over 38 weeks during phase 2; 3) reduced hyperphagia during phases 1 and 2; 4) continued hedonic high-carbohydrate food-seeking in the absence of hunger during phases 1 and 2; and 5) sustained weight reduction during decreased parental monitoring and free access to unlocked food in the home during the last 10 weeks of phase 2.

CONCLUSION

This successful intervention of CP-related hypothalamic obesity and hyperphagia by OT alone and in combination with NAL is promising for conducting future studies of this treatment-recalcitrant form of obesity.

Peripheral and prefrontal stress system markers and risk of relapse in alcoholism

Previous research has shown that hyperactivation in ventral medial prefrontal cortex (VmPFC) and rostral anterior cingulate cortex (rACC) and high cortisol to corticotrophin ratio (cort:ACTH ratio) during neutral-relaxed states predict relapse in alcohol-dependent (AD) patients. Other studies have shown that VmPFC/rACC deactivation and blunted cortisol release to stress and alcohol cues are predictive of time to relapse and relapse severity. However, no previous study has assessed the relationship between these markers of central and peripheral nervous system dysfunction in AD participants and their potential joint effects on relapse risk. Forty early abstinent, treatment engaged AD patients underwent a laboratory experiment with exposure to neutral, alcohol and stress cues and a separate functional magnetic resonance imaging scan with similar cue exposure. Neutral-relaxed state cort:ACTH ratio was significantly associated with VmPFC hyperreactivity to neutral-relaxing cues, and also with hypoactivation in response to alcohol and stress cues in AD patients. Basal heart rate, neutral cort:ACTH ratio and neutral VmPFC hyperreactivty were each associated with risk of relapse. However, abnormal VmPFC activation and elevated cort:ACTH ratio overlap in predicting risk for relapse, and dysfunctional VmPFC response was the sole significant predictor of odds of relapse in a joint model of relapse risk. These findings suggest that the cort:ACTH ratio may serve as a peripheral marker of VmPFC brain dysfunction, while aberrant VmPFC responses need further evaluation as a potential biomarker of alcohol relapse risk in clinical outcome studies.

Adrenocortical sensitivity, moderated by ongoing stress, predicts drinking intensity in alcohol-dependent men

Allostatic load from both environmental stressors and persistent glucocorticoid secretion has been associated with disease severity in alcohol dependence. Heightened relapse risk and/or drinking severity, in particular, may be a reaction to alcohol- and withdrawal-induced changes in physiological stress response systems coupled with ongoing life stress, although their shared contributions upon drinking severity have not been assessed. To investigate the combined contribution of hypothalamic-pituitary-adrenal (HPA) reactivity and environmental stressors (e.g., ongoing life stress) to relapse severity in alcohol-dependent men following treatment, plasma adrenocorticotropin (ACTH) and cortisol were obtained in 4-6 weeks abstinent alcohol-dependent men (n=41) following a psychosocial stressor [the Trier Social Stress Test (TSST)] and two pharmacological provocations [ovine corticotropin releasing factor (oCRH) and cosyntropin]. Following treatment discharge, drinking outcomes (primary outcome: drinks per drinking day (DDD); secondary outcomes: total drinks and drinking days) were assessed weekly and ongoing life stress was assessed biweekly for 24 weeks following treatment discharge. Generalized estimating equation models of drinking severity were fit with basal and stimulated ACTH and cortisol concentrations as predictors and ongoing life stress as the moderator. Greater levels of life stress were independently associated with greater drinking intensity (DDD and total drinks) but not frequency (days drinking). Higher basal cortisol:ACTH or provoked cortisol:ACTH ratios were strongly associated with greater post-treatment DDD in individuals who experienced higher levels of ongoing stress. In conclusion, ongoing life stress is associated with post-treatment drinking intensity in alcohol dependent men; stress also strengthens the relationship between adrenocortical sensitivity and post-treatment drinking. Physiological measures of allostatic load and environmental stressors conjointly increase relapse intensity.

Smoking and Promoter-Specific Deoxyribonucleic Acid Methylation of the Atrial Natriuretic Peptide Gene: Methylation of Smokers and Non-Smokers Differs Significantly during Withdrawal

BACKGROUND

Atrial natriuretic peptide (ANP) is well known in psychiatric disorders to modulate hypothalamic-pituitary-adrenal axis activity. Disturbances of ANP have been described in early abstinent alcohol-dependent patients. This is the first longitudinal investigation on cytosine-phosphatidyl-guanine (CpG)-island promoter methylation of the ANP gene in the blood of tobacco-dependent patients.

METHODS

In a longitudinal approach, we investigated whether changes in ANP serum levels correlated to CpG methylation of the respective gene promoters on days 1, 7, and 14 of tobacco withdrawal.

RESULTS AND CONCLUSION

Compared to non-smokers, promoter-related deoxyribonucleic acid methylation of the ANP promoter was significantly elevated on days 7 and 14 of withdrawal in tobacco-dependent patients. Baseline methylation status of the ANP promoter was not significantly different from controls, arguing for an impaired regulation during withdrawal.

Exercise training - A beneficial intervention in the treatment of alcohol use disorders?

BACKGROUND

A growing body of evidence suggests that exercise training may have multiple beneficial effects in individuals with mental health or substance use disorders. Yet, relatively little knowledge exists regarding the benefits of exercise training to augment treatment for alcohol use disorders (AUDs).

PURPOSE

The purpose of this narrative review is to present a summary of the growing body of published literature supporting exercise training as a treatment strategy for individuals with AUDs. We will provide evidence on the myriad of ways in which exercise may exert a positive effect on AUD outcomes including stress, anxiety, impulsivity, and depression. Further, we will explore how these mechanisms share common neurobiological pathways. The role of exercise in enhancing the social environment and increasing individual self-efficacy to reduce excess and/or inappropriate alcohol consumption will also be discussed.

DISCUSSION

We will conclude with a description of completed investigations involving exercise training and provide suggestions for next steps in this innovative field of study.

Protective Effects of Korean Red Ginseng against Alcohol-Induced Fatty Liver in Rats

The present study tested the hypothesis that Korean red ginseng (KRG) provides a protective effect against alcoholic fatty liver. Male Sprague-Dawley rats were divided into four groups and fed a modified Lieber-DeCarli diet containing 5% (w/v) alcohol or an isocaloric amount of dextrin-maltose for the controls for 6 weeks: normal control (CON), alcohol control (ET), and ET treated with 125 or 250 mg/kg body weight/day of KRG (RGL or RGH, respectively). Compared with the CON group, the ET group exhibited a significant increase in triglycerides, total cholesterol and the presence of lipid droplets in the liver, and a decrease in fat mass, which were all attenuated by KRG supplementation in adose-dependent manner. The mitigation was accompanied by AMP-activated protein kinase (AMPK) signaling pathways in the liver and adipose tissue. In addition, suppression in the alcohol-induced changes of adipose adipokine mRNA expression was also observed in KRG supplementation group. These findings suggest that KRG may have the potential to ameliorate alcoholic fatty liver by suppressing inappropriate lysis of adipose tissue and preventing unnecessary de novo lipogenesis in the liver, which are mediated by AMPK signaling pathways. A mechanism for an interplay between the two organs is still needed to be examined with further assays.

Natriuretic hormones in brain function

Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain. In this review, the established information on the biosynthesis, release and function of NH is discussed, with particular focus on their role in brain function. The available literature on the expression patterns of each of the NH and their receptors in the brain is summarized, followed by the evidence for their roles in modulating brain function. Although numerous open questions exist regarding this issue, the available data support the notion that NH participate in the central regulation of BP, neuroprotection, satiety, and various psychiatric conditions, including anxiety, addiction, and depressive disorders. In addition, the interactions between the different NH in the periphery and the brain are discussed.

Modulation of proopiomelanocortin gene expression by ethanol in mouse anterior pituitary corticotrope tumor cell AtT20

In humans, alcoholism is associated with a decrease in basal ACTH and cortisol levels, and blunted pituitary ACTH responses to administered corticotropin-releasing hormone (CRH) during active drinking and after long-term abstinence. Preclinical studies indicate that a persistent decrease in pituitary activation after chronic exposure to ethanol is due to a direct effect of ethanol on the corticotrope of the anterior pituitary. The present studies were undertaken to determine if ethanol has effects on proopiomelanocortin (POMC) gene transcription activity in mouse anterior pituitary corticotrope tumor cell AtT20. We measured the levels of the POMC primary nuclear RNA transcript (PT), processing intermediate, and mature mRNA in the nucleus and the levels of the POMC mRNA in the cytoplasm after treatment of AtT20 cells with 5-15 mM concentrations of ethanol. After 15 mM ethanol for 60 to 120 min, the POMC PT levels were significantly decreased. This decreased POMC gene transcription activity was coupled with a significant reduction of the POMC cytoplasmic mRNA levels. After ethanol for 4h, however, both the decreases were no longer observed. After 8h, a decrease in the ACTH secretion in the medium was found. We further investigated if CRH or glutamate modulates the effects of ethanol on the POMC gene transcription activity. CRH at 10nM after 60 min increased the POMC PT levels, and 15mM ethanol attenuated the effect of CRH on the nuclear transcription activity. Glutamate receptor proteins, including NMDA receptor subtype NR1 (but not NR2A or NR2B) and GluR2, were identified by Western immunoblot analysis in AtT20 cells, with similar sizes to those in mouse hypothalamus. The inhibitory effect of 60 min ethanol at 5 to 15 mM on the POMC PT levels was attenuated by 50 μM L-glutamate. Together, our data showed that: (1) ethanol treatment in intoxicate doses significantly inhibited POMC gene transcription activity in a dose- and time-dependent manner in AtT20 cells, and (2) the POMC gene transcription activity in response to CRH or glutamate was altered by ethanol. Our results suggest that ethanol has an inhibitory effect on the POMC gene transcription activity in the anterior pituitary corticotrope, which may contribute to the persistent decrease in pituitary activation after chronic ethanol exposure.

Alcohol, stress hormones, and the prefrontal cortex: a proposed pathway to the dark side of addiction

Chronic exposure to alcohol produces changes in the prefrontal cortex that are thought to contribute to the development and maintenance of alcoholism. A large body of literature suggests that stress hormones play a critical role in this process. Here we review the bi-directional relationship between alcohol and stress hormones, and discuss how alcohol acutely stimulates the release of glucocorticoids and induces enduring modifications to neuroendocrine stress circuits during the transition from non-dependent drinking to alcohol dependence. We propose a pathway by which alcohol and stress hormones elicit neuroadaptive changes in prefrontal circuitry that could contribute functionally to a dampened neuroendocrine state and the increased propensity to relapse-a spiraling trajectory that could eventually lead to dependence.

The impact of atrial natriuretic peptide on anxiety, stress and craving in patients with alcohol dependence

AIMS

Atrial natriuretic peptide (ANP) is well known to modulate fluid and electrolyte homeostasis but also to counter-regulate hypothalamic-pituitary-adrenal (HPA) axis activity. Correspondingly, recent studies suggest an important role of ANP in the neurobiology of anxiety. Preclinical and clinical data now provide evidence for an involvement of ANP in the pathophysiology of addictive behavior. The present study aims to elucidate the effects of ANP on alcohol-dependent patients' anxiety, perceived stress and craving during alcohol withdrawal.

METHODS

A sample of 59 alcohol-dependent inpatients was included in the analysis. A blood sample was taken at day 14 of detoxification in order to assess the concentrations of ANP and cortisol in plasma. In parallel, we assessed patients' alcohol craving, using the Obsessive Compulsive Drinking Scale, as well as anxiety (State-Trait Anxiety Inventory). Patients' stress levels were assessed using the Perceived Stress Scale.

RESULTS

We found a significant negative association between patients' ANP plasma concentrations and anxiety, craving for alcohol and perceived stress. Regression analyses suggest that ANP is a significant predictor both for patients' perceived stress and for the severity of anxiety during early abstinence. The association of patients' ANP plasma levels and craving is suggested to be mediated by perceived stress.

CONCLUSION

Our results suggest that the association of patients' ANP plasma levels and craving is mediated by their perceived stress. For this reason, intranasal application of ANP may prove to be a new avenue for the treatment of alcohol dependence in patients exhibiting high levels of perceived stress.

Genome-wide DNA methylation analysis in alcohol dependence

Genetic, epigenetic, and environmental factors influence the development of alcohol dependence (AD). Recent studies have shown that DNA methylation markers in peripheral blood may serve as risk markers for AD. Yet a genome-wide epigenomic approach investigating the role of DNA methylation in AD has yet to be performed. We conducted a population-based, case-control study of genome-wide DNA methylation to determine if alterations in gene-specific methylation were associated with AD in a Chinese population. Using the Illumina Infinium Human Methylation27 BeadChip, we assessed gene-specific methylation in over 27 000 CpG sites from DNA isolated from lymphocytes in 63 male AD in-patients and 65 male healthy controls. Using a multi-factorial statistical model, we observed differential methylation between cases and controls at multiple CpG sites with the majority of the methylated CpG sites being hypomethylated. Analyses with the online gene set analysis toolkit WebGestalt revealed that the genes of interest were enriched in multiple biological processes involved in AD development. Gene Ontology function annotation showed that stress, immune response and signal transduction were highly associated with AD. Further analysis by the Kyoto Encyclopedia of Genes and Genomes revealed associations with multiple pathways involved in metabolism through cytochrome P450, cytokine-cytokine receptor interaction and calcium signaling. Associations with canonical pathways previously shown to be involved in AD were also observed, such as dehydrogenases 1A (ADH1A), ADH7, aldehyde dehydrogenases 3B2 (ALDH3B2) and cytochrome P450 2A13. We present evidence that alterations in DNA methylation may be associated with AD, which is consistent with epigenetic theory.

The genetics of the opioid system and specific drug addictions

Addiction to drugs is a chronic, relapsing brain disease that has major medical, social, and economic complications. It has been established that genetic factors contribute to the vulnerability to develop drug addiction and to the effectiveness of its treatment. Identification of these factors may increase our understanding of the disorders, help in the development of new treatments and advance personalized medicine. In this review, we will describe the genetics of the major genes of the opioid system (opioid receptors and their endogenous ligands) in connection to addiction to opioids, cocaine, alcohol and methamphetamines. Particular emphasis is given to association and functional studies of specific variants. We will provide information on the sample populations and the size of each study, as well as a list of the variants implicated in association with addiction-related phenotypes, and with the effectiveness of pharmacotherapy for addiction.

Augmented stress-induced alcohol drinking and withdrawal in mice lacking functional natriuretic peptide-A receptors

AIMS

Preclinical and clinical data suggest an involvement of atrial natriuretic peptides (ANP) in alcohol-associated psychopathology. We now present first data on alcohol drinking behaviour in mice lacking a functional natriuretic peptide-A (NPR-A) receptor.

METHODS

NPR-A(-/-) and wild-type mice were given a free choice between water and increasing concentrations of alcohol (2-16%). A forced swim stress was performed thereafter on three consecutive days to investigate stress-induced alcohol drinking. Additionally, neurobehavioural alcohol withdrawal response was investigated following 14 days of forced-alcohol intake.

RESULTS

Whereas basal alcohol intake did not differ between NPR-A mutants and wild-type littermates, NPR-A mutants showed an increased stress-induced alcohol intake and aggravated neurobehavioural symptoms of alcohol withdrawal.

CONCLUSIONS

Mice lacking a functional NPR-A receptor represent a useful model to study the role of the ANP system in alcohol-associated pathology. To study the role of the natriuretic NPR-A gene for the modulation of risk of alcohol-related disorders, NPR-A-related polymorphisms should be targeted in clinical studies.

Pro-opiomelanocortin gene variation related to alcohol or drug dependence: evidence and replications across family- and population-based studies

BACKGROUND

Opioidergic neurotransmission is critical in many, possibly all, forms of substance dependence. Several opioid-system genes have been shown to be associated with substance dependence disorders. The pro-opiomelanocortin gene (POMC) encodes several peptides important for endogenous opioidergic neurotransmission. We tested whether POMC genetic variation affects risk for substance dependence.

METHODS

Five single nucleotide polymorphisms spanning POMC were examined in independent family and case-control samples. Family-based studies included 854 subjects from 319 African American (AA) families and 761 subjects from 313 European American (EA) families. Each family had a pair of siblings affected with cocaine and/or opioid dependence. Case-control studies included 791 cases (455 AAs and 336 EAs) affected with alcohol, cocaine, and/or opioid dependence and 682 control subjects (199 AAs and 483 EAs).

RESULTS

Family-based analyses revealed an association of rs6719226 with opioid dependence in AA families and rs6713532 with cocaine dependence in EA families (p = .010-.044). Case-control analyses demonstrated an association of rs6713532 with alcohol or cocaine dependence in EAs (p(allele-wise) = .003-.008). Moreover, the minor allele of rs1866146 was found to be a risk factor for cocaine or opioid dependence in AAs (p(allele-wise) = .010-.017) and for alcohol, cocaine, or opioid dependence in EAs (p(allele-wise) = .001-.003). Logistic regression analyses in which sex and age were considered and population stratification analyses confirmed these findings. Additionally, specific haplotypes increased risk for cocaine dependence (p = .023) in AAs and opioid dependence (p = .012) in EAs.

CONCLUSIONS

Given these replicated results, we conclude that variation in POMC confers vulnerability to multiple forms of substance dependence.

HPA-axis activity in alcoholism: examples for a gene-environment interaction

Genetic and environmental influences are both known to be causal factors in the development and maintenance of substance abuse disorders. This review aims to focus on the contributions of genetic and environmental research to the understanding of alcoholism and how gene-environment interactions result in a variety of addiction phenotypes. Gene-environment interactions have been reviewed by focusing on one of the most relevant environmental risk factors for alcoholism, stress. This is examined in more detail by reviewing the functioning of the hypothalamic-pituitary-adrenal (HPA) axis and its genetic and molecular components in this disorder. Recent evidence from animal and human studies have shown that the effects of stress on alcohol drinking are mediated by core HPA axis genes and are associated with genetic variations in those genes. The findings of the studies discussed here suggest that the collaborations of neuroscience, psychobiology and molecular genetics provide a promising framework to elucidate the exact mechanisms of gene-environment interactions as seen to convene upon the HPA axis and effect phenotypes of addiction.

Alcoholism, craving, and hormones: the role of leptin, ghrelin, prolactin, and the pro-opiomelanocortin system in modulating ethanol intake

Evidence is growing that appetite regulating peptides such as leptin and ghrelin, but also other hormones including prolactin are altered in alcoholism. The brain pro-opiomelanocortin (POMC) system which has important mediating roles in alcohol intake also has important functions in prolactin regulation and energy homeostasis. Furthermore, it has been demonstrated to be functionally integrated with leptin regulation. The satiety factor leptin seems to be counteracted by the gut-derived peptide ghrelin which increases hunger and food intake. Consequently, the POMC system may have a role in integrating regulation of alcohol effects and these seemingly disparate regulatory systems. The goal of this mini-review is to discuss the results of some recent investigations of the potential interactions of these systems with acute and chronic alcohol responses.

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.

Adrenocorticotropic Hormone/Cortisol Response to Physical Exercise in Abstinent Alcoholic Patients

BACKGROUND

Alterations in the hypothalamic-pituitary-adrenal (HPA) axis in alcoholic patients have been reported in various experimental conditions.

METHODS

To establish whether alcoholism affects the HPA axis activation during physical exercise, 10 recent abstinent alcoholic patients (age range: 33-45 years; duration of alcohol dependence: range 4-6 years) were tested by exercising on a bicycle ergometer. Ten age-matched healthy nonalcoholic men participated as controls. The workload was gradually increased at 3-minute intervals until exhaustion and lasted about 15 minutes for all subjects. Alcoholic patients were tested at 3 time points, at 4, 6, and 8 weeks after alcohol withdrawal, whereas controls were tested only once. Main outcome measurements were circulating levels of adrenocorticotropic hormone (ACTH) and cortisol and physiological variables during physical exercise [heart rate, blood pressure, ventilation, frequency of breathing, tidal volume, oxygen consumption (VO2), carbon oxide production (VCO2), and respiratory exchange ratio (R)].

RESULTS

Similar basal and exercise-induced changes in physiological variables were observed in controls and alcoholic patients in all tests. Basal levels of ACTH and cortisol were similar in all tests performed on alcoholic patients and on normal controls. In normal subjects, exercise induced a significant increase in plasma ACTH and serum cortisol levels, with peak levels at 20 minutes for ACTH (84% higher than baseline) and at 30 minutes for cortisol (70% higher than baseline). After 4 weeks of abstinence, slight but not significant ACTH/cortisol responses to physical exercise were observed in alcoholic patients (mean peaks were 10 and 18% higher than baseline, respectively, for ACTH and cortisol). By contrast, when the exercise test was repeated after 6 weeks abstinence, ACTH/cortisol levels rose significantly versus baseline (mean peak levels of ACTH and cortisol were 48 and 38% higher than baseline, respectively, for ACTH and cortisol). However, the hormonal responses were significantly lower than in the normal controls. At 8 weeks of abstinence, ACTH/cortisol responses were significantly higher than 2 weeks previously, and were not distinguishable from the increments observed in the normal controls (76 and 68% higher than baseline, respectively, for ACTH and cortisol).

CONCLUSIONS

In concurrence with previous reports showing alterations of the HPA axis in the central nervous system in alcohol-dependent subjects, these data show a defect of the neuroendocrine mechanism(s) underlying the ACTH/cortisol response to physical exercise for at least a month after alcohol withdrawal, with reconstitution of a normal hormonal response at 8 weeks.

Influence of naltrexone administration on dehydroepiandrosterone sulfate levels in male and female participants

Dehydroepiandrosterone sulfate (DHEAS) is an excitatory neurosteroid with anti-glucocorticoid properties. Endogenous opioid system blockade is known to activate the hypothalamic-pituitary-adrenal axis and other hormonal systems. However, the literature is sparse regarding the extent to which this blockade acutely influences DHEAS activity. Further, the stability of DHEAS concentrations across short term laboratory studies is not well established. The current study examined these issues in human participants. Using a double-blind, counterbalanced design, 50mg of naltrexone and placebo were administered. Repeated salivary samples were then obtained over a 3h period while participants completed a nociceptive testing paradigm. DHEAS and cortisol concentrations were determined. Naltrexone administration was associated with an increase in cortisol concentrations; however, DHEAS was unaffected by naltrexone and did not vary across the course of the study. This finding is an important contribution to the methodological literature, and may be used to verify the stability of DHEAS for future investigations.

Understanding and treating alcohol dependence

This article represents the proceedings of a symposium presented at the 158th Annual Meeting of the American Psychiatric Association held in Atlanta, Georgia, on May 24, 2005. The organizer/chairman was Bankole A. Johnson, DSc, MD, PhD. The presentations included the following: (1) Neuropharmacological Basis of Alcohol Dependence, by George F. Koob, PhD; (2) Recent Developments in the Genetics of Alcohol Dependence, by Marc A. Schuckit, MD; (3) New Pharmacological Strategies for Treating Alcohol Dependence, by Barbara J. Mason, PhD; (4) New Medications: The Use of Anticonvulsants, Both Alone and in Combination, with Various Forms of Psychotherapy, by Bankole A. Johnson, DSc, MD, PhD; and (5) Differential Effects of Pharmacological Agents on Craving, by Nassima Ait-Daoud, MD.

Alteration of prolactin serum levels during alcohol withdrawal correlates with craving in female patients

Dopaminergic transmission has been suggested to be a main mechanism mediating reinforcement, withdrawal and craving in alcohol dependency. Dopamine is associated with prolactin secretion, acting as a prolactin inhibitor. The aim of the present study was to investigate whether there is an association between altered prolactin levels and craving during early and late alcohol withdrawal. Therefore, we examined 145 patients suffering from alcohol dependency after admission to the detoxification unit, assessing craving with the Obsessive Compulsive Drinking Scale (OCDS) and measuring prolactin serum levels during early withdrawal (-EW: day 0 or day 1) and late withdrawal (-LW: day 7-day 10). We observed a significant influence of the alteration of prolactin during withdrawal on craving in female patients (Spearman's rho, OCDS-EW: r=-0.607, p=0.001; OCDS-LW: r=-0.730, p<0.001; n=26). The association between prolactin alteration in percentage and craving in females was confirmed with general linear models (OCDS-EW: F=15.819, p=0.001, r(2)=0.530; OCDS-LW: F=17.091, p<0.001, r(2)=0.535). In male patients we did not find any significant results. Our findings support the previously described role of the hypothalamic-pituitary-adrenal (HPA) axis in the neurobiology of alcohol craving and show evidence of an association between increased prolactin serum levels and lower craving during alcohol withdrawal in female patients.

VOLUME INTAKE AND CRAVING IN ALCOHOL WITHDRAWAL

AIMS

It has been shown that beer consumption is associated with alcohol craving, in contrast to wine or spirits consumption. The present study was undertaken to evaluate whether the daily volume intake of alcoholic beverages is associated with craving in patients undergoing alcohol withdrawal.

METHODS

A total of 158 male patients were assessed using the obsessive compulsive drinking scale (OCDS) at admission. The daily volume intake of alcoholic beverages was calculated by adding the volume of all regularly consumed alcoholic beverages, disregarding their alcohol percentage. Lesch's typology was used to classify patients for subgroup analysis.

RESULTS

The daily volume intake of alcoholic beverages correlated significantly with the extent of the OCDS (r = 0.33; P < 0.001). With general linear models, we found a significant association of the calculated daily volume intake of all alcoholic beverages with craving (F = 6.426; P = 0.012), but not for the daily ethanol intake. Differentiating the patients according to Lesch's typology a significant association was particularly found in Lesch Type 2 (model of anxiety) patients (F = 11.31; P = 0.001).

CONCLUSION

Our results support the hypothesis that volume intake is associated with craving and suggest a role of pathophysiological changes in volume regulating mechanisms (such as vasopressin or ANP) in the neurobiology of alcohol craving, particularly in male patients of Lesch's Type 2 undergoing alcohol withdrawal.

Dissection of hypothalamic-pituitary-adrenal axis pathology in 1-month-abstinent alcohol-dependent men, part 1: adrenocortical and pituitary glucocorticoid responsiveness

BACKGROUND

Long-term ingestion of alcohol produces marked alterations in hypothalamic-pituitary-adrenal axis activity. The authors engaged in a series of studies to determine the distinct role of the hypothalamus and the pituitary and adrenal glands in the disturbances observed in abstinent alcohol-dependent subjects. In this first of a two-part study, the authors report on (1) the basal secretory profile of corticotropin and cortisol from 2000 to 0800 hrs, (2) adrenocortical sensitivity in both the presence and absence of endogenous pituitary activation, and (3) pituitary glucocorticoid sensitivity to dexamethasone.

METHODS

Eleven male, 4 to 6 weeks abstinent, alcohol-only-dependent subjects and 10 age-matched male healthy controls were studied. Basal circulating concentrations of corticotropin and cortisol were obtained from 2000 to 0800 hr. A submaximal dose of cosyntropin (0.01 microg/kg), a corticotropin analogue was then administered to assess adrenocortical sensitivity. In a separate session, cosyntropin was administered following high-dose dexamethasone (8 mg iv) to assess adrenocortical sensitivity in the relative absence of endogenous corticotropin. In addition, the corticotropin response to dexamethasone was measured to determine pituitary glucocorticoid responsiveness.

RESULTS

Cortisol, but not corticotropin, pulse amplitude (p < 0.05) and mean concentration (p= 0.05) was significantly lower in alcohol-dependent subjects compared with controls. The cortisol response to cosyntropin was lower in alcohol-dependent subjects following endogenous corticotropin suppression by high-dose dexamethasone (p <0.04) but not without dexamethasone pretreatment. Mean corticotropin (p <0.004) and cortisol (p <0.05) concentrations in response to dexamethasone were attenuated in the patients compared to controls. Basal concentrations of 11-deoxycortisol, the precursor to cortisol, were also decreased in alcohol-dependent subjects (p <0.05).

CONCLUSION

Attenuated basal and stimulated adrenocortical concentrations in abstinent alcohol-dependent men are coupled with a nonhomeostatic increase in pituitary glucocorticoid inhibition. A decrease in stress-axis responsivity in alcohol dependence may have implications for treatment outcome.

Suppression of the HPA axis stress-response: implications for relapse

This article presents the proceedings of a symposium held at the meeting of the International Society for Biomedical Research on Alcoholism (ISBRA) in Mannheim, Germany, in October 2004. This symposium explored the potential role of hypothalamic-pituitary-adrenal (HPA) axis dysregulation upon relapse. HPA axis stimulation induces the release of the glucocorticoid cortisol, a compound with profound effects upon behavior and emotion. Altered stress-responses of the HPA axis in abstinent alcohol-dependent subjects, therefore, may influence their affective and behavioral regulation, thus impacting their potential for relapse. Bryon Adinoff began the symposium with a review of HPA axis dysfunction in alcohol-dependent subjects, including recent studies from his lab demonstrating an attenuated glucocorticoid response to both endogenous and exogenous stimulation in one-month abstinent men. Klaus Junghanns presented his work demonstrating that a blunted ACTH or cortisol response to subjective stressors (social stressor or alcohol exposure) is predictive of a return to early drinking. The final two presenters examined the interaction between naltrexone and HPA responsiveness in alcohol-dependent or at-risk subjects, as naltrexone induces an increase in ACTH and cortisol. Falk Kiefer discussed the relationship between basal HPA axis responsivity and clinical outcome following treatment with naltrexone or acamprosate. Plasma ACTH significantly decreased over the course of the study in the placebo group, but not the medication groups [corrected] Lower basal concentrations of ACTH and cortisol were associated with quicker relapse in the placebo group only. Suchitra Krishnan-Sarin described her preliminary work, in which family-history positive (FH+) and family history negative (FH-) subjects were administered naltrexone, followed by an assessment of alcohol-induced craving. The cortisol response to alcohol was significantly and inversely related to craving in the FH+, but not the FH-, subjects. Alterations in HPA axis responsivity may therefore have a negative impact upon clinical outcome in alcohol-dependent subjects, and disinhibition of the axis with medication may have therapeutic potential.

SALIVARY CORTISOL: A PREDICTOR OF CONVICTIONS FOR DRIVING UNDER THE INFLUENCE OF ALCOHOL?

AIMS

To examine the relationship between salivary cortisol and frequency of past driving under the influence of alcohol (DUI) convictions.

METHODS

A total of 104 males with previous DUI convictions (from one to eight) and mean age of 44.7 years were assessed on measures characterizing repeat DUI offenders, including sociodemographic information, alcohol use behaviours, biological indices of the organic consequences of chronic abuse, negative consequences of excessive drinking, past DUI conviction history, impulse control, and antisocial behaviour tendencies. Saliva samples were taken approximately every 30 min over a 6 h period during an exhaustive multidimensional assessment protocol, and were then assayed to obtain cortisol responses.

RESULTS

Blunted cortisol response, typically observed in alcoholics and in high-risk non-alcoholics, was associated with increased number of past DUI convictions. This association was particularly pronounced in multiple DUI offenders, and was stronger than, and independent of, other measures of alcohol use severity and chronicity commonly used for DUI assessment.

CONCLUSIONS

Cortisol response may be useful in understanding the mediators underlying repeat DUI offending and the frequent failure of intervention efforts in curbing DUI behaviour.

Dissection of hypothalamic-pituitary-adrenal axis pathology in 1-month-abstinent alcohol-dependent men, part 2: response to ovine corticotropin-releasing factor and naloxone

BACKGROUND

Pituitary and adrenal responsiveness is suppressed in abstinent alcohol-dependent individuals. To clarify the specific organizational disruption in hypothalamic-pituitary-adrenal functioning during early abstinence, the authors separately assessed each level of the stress-response axis. In this second of a two-part study, ovine corticotropin-releasing factor (oCRH) was used to stimulate the pituitary corticotrophs, and naloxone was used to activate the axis at the hypothalamic level. In addition, pulsatile characteristics of corticotropin and cortisol were assessed over a 12-hr period (0800 to 2000 hr).

METHODS

Eleven abstinent alcohol-dependent men and 10 healthy comparison participants were assessed. All participants were between the ages of 30 and 50 years, and alcohol-dependent patients were abstinent from 4 to 6 weeks. Basal concentrations of corticotropin and cortisol were obtained every 10 min from 0800 to 2000 hr and subjected to pulsatile analysis. Plasma corticotropin and cortisol concentrations were then obtained every 5 to 10 min after low-dose, intravenously administered doses of oCRH (0.4 microg/kg) or naloxone (0.125 mg/kg). Medications were administered at 2000 hr and the two challenge studies were separated by 48 hr.

RESULTS

Pulsatile analysis revealed that the mean corticotropin amplitude was increased in alcohol-dependent patients relative to controls (p <0.05). Other pulsatile characteristics of corticotropin and all cortisol pulsatile measures were not significantly different between the two groups. The integrated cortisol response to oCRH was significantly lower in alcohol-dependent patients compared with controls (p <0.01), but the integrated corticotropin response was not significantly different. In contrast, neither the corticotropin nor the cortisol response to naloxone was significantly different between groups.

CONCLUSIONS

Adrenocorticoid hyposensitivity persists after oCRH infusion for at least 1 month after cessation of drinking, whereas hyporesponsiveness of the pituitary corticotrophs to CRH seems to resolve with continued abstinence. The authors suggest that adrenocortical hyporesponsiveness during prolonged abstinence may impact relapse risk.

Alcoholism and neuro-immune-endocrine interactions: physiochemical aspects

The role of alcohol consumption and alcoholism as an addiction in regulating the chemistry of the brain and its physiology has gained a backlog of interest over the past few decades. Besides the notion that alcohol acts as a brain depressant, the molecular mechanisms and neuronal interactions are not well understood. Emerging evidence implicates alcohol as a neurochemical messenger that influences a cross talk amongst the nervous, immune, and endocrine systems. Specifically, alcohol acts as a crucial regulator of the hypothalamic-pituitary-adrenal (HPA) axis, thereby modulating the release of hormones, particularly adrenocorticotropic hormone (ACTH) and corticosterone (CORT). It is the aim of this review, therefore, to investigate current concepts on how alcohol, particularly ethanol, and alcoholism affect neuro-immune-endocrine neurochemical interactions via the regulation of the HPA axis, taking into consideration bio-behavioral and physiochemical aspects.

Neurobiologic processes in drug reward and addiction

Neurophysiologic processes underlie the uncontrolled, compulsive behaviors defining the addicted state. These"hard-wired"changes in the brain are considered critical for the transition from casual to addictive drug use. This review of preclinical and clinical (primarily neuroimaging) studies will describe how the delineation between pleasure, reward, and addiction has evolved as our understanding of the biologic mechanisms underlying these processes has progressed. Although the mesolimbic dopaminergic efflux associated with drug reward was previously considered the biologic equivalent of pleasure, dopaminergic activation occurs in the presence of unexpected and novel stimuli (either pleasurable or aversive) and appears to determine the motivational state of wanting or expectation. The persistent release of dopamine during chronic drug use progressively recruits limbic brain regions and the prefrontal cortex, embedding drug cues into the amygdala (through glutaminergic mechanisms) and involving the amygdala, anterior cingulate, orbitofrontal cortex, and dorsolateral prefrontal cortex in the obsessive craving for drugs. The abstinent, addicted brain is subsequently primed to return to drug use when triggered by a single use of drug, contextual drug cues, craving, or stress, with each process defined by a relatively distinct brain region or neural pathway. The compulsive drive toward drug use is complemented by deficits in impulse control and decision making, which are also mediated by the orbitofrontal cortex and anterior cingulate. Within this framework, future targets for pharmacologic treatment are suggested.