Role of Appetite-Regulating Peptides in Alcohol Craving: An Analysis in Respect to Subtypes and Different Consumption Patterns in Alcoholism

Cluster analysis in gambling disorder based on sociodemographic, neuropsychological, and neuroendocrine features regulating energy homeostasis

BACKGROUND

The heterogeneity of gambling disorder (GD) has led to the identification of different subtypes, mostly including phenotypic features, with distinctive implications on the GD severity and treatment outcome. However, clustering analyses based on potential endophenotypic features, such as neuropsychological and neuroendocrine factors, are scarce so far.

AIMS

This study firstly aimed to identify empirical clusters in individuals with GD based on sociodemographic (i.e., age and sex), neuropsychological (i.e., cognitive flexibility, inhibitory control, decision making, working memory, attention, and set-shifting), and neuroendocrine factors regulating energy homeostasis (i.e., leptin, ghrelin, adiponectin, and liver-expressed antimicrobial peptide 2, LEAP-2). The second objective was to compare the profiles between clusters, considering the variables used for the clustering procedure and other different sociodemographic, clinical, and psychological features.

METHODS

297 seeking-treatment adult outpatients with GD (93.6% males, mean age of 39.58 years old) were evaluated through a semi-structured clinical interview, self-reported psychometric assessments, and a protocolized neuropsychological battery. Plasma concentrations of neuroendocrine factors were assessed in peripheral blood after an overnight fast. Agglomerative hierarchical clustering was applied using sociodemographic, neuropsychological, and neuroendocrine variables as indicators for the grouping procedure. Comparisons between the empirical groups were performed using Chi-square tests (χ2) for categorical variables, and analysis of variance (ANOVA) for quantitative measures.

RESULTS

Three-mutually-exclusive groups were obtained, being neuropsychological features those with the greatest weight in differentiating groups. The largest cluster (Cluster 1, 65.3%) was composed by younger males with strategic and online gambling preferences, scoring higher on self-reported impulsivity traits, but with a lower cognitive impairment. Cluster 2 (18.2%) and 3 (16.5%) were characterized by a significantly higher proportion of females and older patients with non-strategic gambling preferences and a worse neuropsychological performance. Particularly, Cluster 3 had the poorest neuropsychological performance, especially in cognitive flexibility, while Cluster 2 reported the poorest inhibitory control. This latter cluster was also distinguished by a poorer self-reported emotion regulation, the highest prevalence of food addiction, as well as a metabolic profile characterized by the highest mean concentrations of leptin, adiponectin, and LEAP-2.

CONCLUSIONS

To the best of our knowledge, this is the first study to identify well-differentiated GD clusters using neuropsychological and neuroendocrine features. Our findings reinforce the heterogeneous nature of the disorder and emphasize a role of potential endophenotypic features in GD subtyping. This more comprehensive characterization of GD profiles could contribute to optimize therapeutic interventions based on a medicine of precision.

Ghrelin and impulsivity relationship in alcohol-dependent patients and healthy individuals

AIMS

Abundant research indicates that ghrelin hormone levels are associated with alcohol use and addiction. One of the mediators of this association may be impulsivity, which is one of the common traits observed in alcohol addiction and some eating disorders. This study evaluated participants with alcohol dependency and healthy volunteers to determine whether trait impulsivity and ghrelin levels are associated.

METHODS

This study analyzed trait impulsivity scores and fasting serum ghrelin levels of 44 males with alcohol dependency and 48 healthy male participants. The Barratt Impulsiveness Scale and the UPPS Impulsive Behaviour Scale (UPPS) were used to measure trait impulsivity levels. Penn Alcohol Craving Scale and Yale Brown Obsessive Compulsive Drinking Scale for heavy drinking were used to assess craving at the baseline and after the detoxification period.

RESULTS

Alcohol-dependent patients' fasting ghrelin levels were significantly higher than that of healthy participants. Ghrelin plasma levels were positively correlated with UPPS total impulsivity scores and sensation-seeking among healthy individuals. In alcohol-dependent participants, there was a positive correlation between UPPS urgency scores obtained at the baseline and fasting ghrelin levels before and after the detoxification period.

CONCLUSIONS

Ghrelin-impulsivity relationship could be observed in certain dimensions of impulsivity in both alcohol-dependent and healthy individuals and even independent of the effect of alcohol. Although the associated impulsivity dimensions differ in different groups, the results are parallel to other studies in terms of demonstrating the relationship between ghrelin and impulsivity.

A closer look at alcohol-induced changes in the ghrelin system: novel insights from preclinical and clinical data

Ghrelin is a gastric-derived peptide hormone with demonstrated impact on alcohol intake and craving, but the reverse side of this bidirectional link, that is, the effects of alcohol on the ghrelin system, remains to be fully established. To further characterize this relationship, we examined (1) ghrelin levels via secondary analysis of human laboratory alcohol administration experiments with heavy-drinking participants; (2) expression of ghrelin, ghrelin receptor, and ghrelin-O-acyltransferase (GOAT) genes (GHRL, GHSR, and MBOAT4, respectively) in post-mortem brain tissue from individuals with alcohol use disorder (AUD) versus controls; (3) ghrelin levels in Ghsr knockout and wild-type rats following intraperitoneal (i.p.) alcohol administration; (4) effect of alcohol on ghrelin secretion from gastric mucosa cells ex vivo and GOAT enzymatic activity in vitro; and (5) ghrelin levels in rats following i.p. alcohol administration versus a calorically equivalent non-alcoholic sucrose solution. Acyl- and total-ghrelin levels decreased following acute alcohol administration in humans, but AUD was not associated with changes in central expression of ghrelin system genes in post-mortem tissue. In rats, alcohol decreased acyl-ghrelin, but not des-acyl-ghrelin, in both Ghsr knockout and wild-type rats. No dose-dependent effects of alcohol were observed on acyl-ghrelin secretion from gastric mucosa cells or on GOAT acylation activity. Lastly, alcohol and sucrose produced distinct effects on ghrelin in rats despite equivalent caloric value. Our findings suggest that alcohol acutely decreases peripheral ghrelin concentrations in vivo, but not in proportion to alcohol's caloric value or through direct interaction with ghrelin-secreting gastric mucosal cells, the ghrelin receptor, or the GOAT enzyme.

The association of plasma acyl ghrelin level with alcohol craving in early abstinent alcohol dependent patients

Background

Craving plays an important role in maintenance of alcohol dependence. Earlier studies have analyzed the role of ghrelin in craving and their results have been heterogenous. Acyl ghrelin is its more active form as it crosses the blood brain barrier. Hence we aimed to examine the relationship between plasma acyl ghrelin and craving in Indian patients having alcohol dependence syndrome.

Methods

The present study was a hospital-based prospective study. A total of 60 drug-naive patients of alcohol dependence and 30 healthy controls were included. After taking informed consent fasting blood samples were collected from them on day 1 and tested for plasma acyl ghrelin level. Fasting blood samples were repeated in all cases on day 14. During this time, we also assessed the patients' cravings by obsessive compulsive drinking scale, and alcohol craving questionnaire; and withdrawal by clinical institute withdrawal assessment for alcohol scale. These scales were repeated on day 14. Data analysis was done by SPSS version 25.0.

Results

Plasma concentrations of acyl ghrelin increased significantly during early abstinence in patients from day 1 to day 14 (P < 0.0001). Pearson correlation test revealed a trend of positive correlation between plasma concentration of acyl ghrelin on day 14 and severity of craving on day 1.

Conclusion

Our results suggest the plasma concentration of acyl ghrelin may be a predictor of severity of alcohol craving during early abstinence. Anti-craving drugs acting on acyl ghrelin level in brain may open an innovative avenue for optimum treatment of alcohol dependence.

An overview of ghrelin O-acyltransferase inhibitors: a literature and patent review for 2010-2019

INTRODUCTION

The peptide hormone ghrelin regulates physiological processes associated with energy homeostasis such as appetite, insulin signaling, glucose metabolism, and adiposity. Ghrelin has also been implicated in a growing number of neurological pathways involved in stress response and addiction behavior. For ghrelin to bind the growth hormone secretagogue receptor 1a (GHS-R1a) and activate signaling, the hormone must first be octanoylated on a specific serine side chain. This key transformation is performed by the enzyme ghrelin O-acyltransferase (GOAT), and therefore GOAT inhibitors may be useful in treating disorders related to ghrelin signaling such as diabetes, obesity, and related metabolic syndromes.

AREAS COVERED

This report covers ghrelin and GOAT as potential therapeutic targets and summarizes work on GOAT inhibitors through the end of 2019, highlighting recent successes with both peptidomimetics and small molecule GOAT inhibitors as potent modulators of GOAT-catalyzed ghrelin octanoylation.

EXPERT OPINION

A growing body of biochemical and structural knowledge regarding the ghrelin/GOAT system now enables multiple avenues for identifying and optimizing GOAT inhibitors. We are at the beginning of a new era with increased opportunities for leveraging ghrelin and GOAT in the understanding and treatment of multiple health conditions including diabetes, obesity, and addiction.

The Impact of Appetite-Regulating Neuropeptide Leptin on Alcohol Use, Alcohol Craving and Addictive Behavior: A Systematic Review of Preclinical and Clinical Data

AIMS

The appetite regulating hormone leptin, which is mainly secreted from adipose tissue, is an important regulator of food intake and modulator of reward-driven behavior. Leptin exerts its biological actions via binding to the leptin receptor, which is expressed in the hypothalamus, but also in the hippocampus, the amygdala and the substantia nigra. In the ventral tegmental area (VTA), leptin attenuates the firing rate of dopaminergic neurons that project to the Nucleus accumbens (NAc), which serves as relay to other brain areas of the "addiction network", such as the prefrontal cortex. This suggests that leptin plays a role in the processing of rewards in the context of substance use disorders such as alcohol use disorder, especially through attenuation of dopaminergic activity in the mesolimbic reward system. This supports the plausibility of leptin's potential effects in alcohol use disorder.

METHODS

We searched MEDLINE from 1990 to February 2020. All abstracts were screened for relevance and we only included publications reporting original data with a full text available in English language. Studies that did not report leptin-data, reviews or case reports/series were not included.

RESULTS

We identified a total of N=293 studies of whom a total of N=55 preclinical and clinical studies met the specified criteria. N=40 studies investigated the effects of alcohol on leptin plasma levels, N=9 studies investigated the effects of leptin on alcohol craving and N=6 studies investigated the effects of leptin on relapse and alcohol consumption.

CONCLUSIONS

In this review of preclinical and clinical data, we assess the role of leptin in alcohol use and the development and maintenance of an alcohol use disorder, alcohol craving and relapse. Integrating the existing preclinical and clinical data on leptin may reveal new and innovative targets for the treatment of substance use disorders in the future.

Effects of ethanol on plasma ghrelin levels in the rat during early and late adolescence

Ghrelin is an appetite-regulating peptide that is primarily secreted by endocrine cells in the stomach and is implicated in regulation of alcohol consumption and alcohol-reinforced behaviors. In the present study, adolescent Sprague-Dawley rats received intermittent ethanol (AIE) exposure by intragastric intubation (5 g/kg) or vapor inhalation, manipulations conducted between postnatal days (PD) 28-43. On the first and last day of AIE exposure, the level of intoxication was examined 1 h after ethanol gavage or upon removal from the vapor chamber. This was immediately followed by a blood draw for determination of the blood ethanol concentration (BEC) and plasma levels of acylated ghrelin (acyl-ghrelin; active). On PD29, plasma levels of acyl-ghrelin were significantly elevated in male (but not female) rats in response to acute ethanol exposure by both gastric gavage and vapor inhalation. Importantly, assessment of plasma acyl-ghrelin in response to repeated ethanol exposure revealed a complex interaction of both sex and method of AIE exposure. On PD43, vapor inhalation increased plasma acyl-ghrelin in both males and females compared to their air-control counterparts, whereas there was no change in plasma levels of acyl-ghrelin in either male or female rats in response to exposure by intragastric gavage. Assessment of plasma acyl-ghrelin following a 30-day ethanol-free period revealed AIE exposure did not produce a change in basal levels. In addition, an acute ethanol challenge in adult rats of 5 g/kg via gastric gavage had no effect on plasma ghrelin levels when assessed 1 h after initiation of exposure. Collectively, these observations suggest that acyl-ghrelin, a primary gut-brain signaling hormone, is elevated by ethanol during early adolescence independent of administration route, and in gender-dependent fashion.

Serum lipids, leptin, and soluble leptin receptor in alcohol dependence: A cross-sectional and longitudinal study

OBJECTIVE

Alcohol dependence affects metabolic processes. Further research is needed to apply this knowledge clinically. In this study, possible differences in serum lipids and/or leptin activities between alcohol-dependent in-patients and healthy controls and possible associations with alcohol-related blood parameters and with prospective outcomes in alcohol dependence were assessed sex-specifically.

METHOD

We measured and compared (median) serum lipids (triglycerides and total, HDL, and LDL cholesterol) and leptin activities (leptin, soluble leptin receptor [ObRe], and free leptin index) in 200 (males 56.5 %) early-abstinent alcohol-dependent in-patients and 240 (males 55.4 %) healthy controls and assessed alcohol-related readmissions during a 24 -month post-inclusion period.

RESULTS

Male patients showed higher HDL cholesterol (61 versus 48 mg/dl), lower LDL/HDL ratios (2.06 versus 3.04), and lower free leptin index (0.30 versus 0.59) at study inclusion compared to healthy controls. In patients, ObRe levels were higher than in controls and decreased from inclusion to the second study-visit (at median 5 days later; males: 16.7-13.8 versus 11.0 ng/ml; females: 17.0-13.4 versus 12.1 ng/ml). The free leptin index increased between the two time points in females (0.80 versus 1.20). Lipids and leptin activities correlated with carbohydrate-deficient transferrin levels and liver enzyme activities. None of the serum parameters were significantly associated with alcohol-related readmissions.

CONCLUSION

Our data support that serum lipid levels and leptin activities are involved in alcohol dependence. The parameters appear as possible indirect biomarkers for alcohol dependence.

Ghrelin modulates mesolimbic reactivity to alcohol cues in alcohol-addicted subjects: a functional imaging study

Ghrelin has been shown to be involved in the pathophysiology of alcohol dependence, affecting alcohol self-administration and craving. However, the mechanism of action in alcohol dependence still has to be determined. We thus investigated whether ghrelin is associated with mesolimbic cue reactivity to alcohol cues and alcohol craving in recently detoxified alcohol-addicted subjects. We included 41 recently detoxified alcohol-dependent individuals. Functional magnetic resonance imaging (fMRI) was used to study mesolimbic cue reactivity during the presentation of alcohol-related pictures. Additionally, we assessed patients' alcohol craving using the Alcohol Urge Questionnaire and a visual analogue scale. Plasma concentrations of total and acylated (activated) ghrelin were measured in parallel to the fMRI session. The association between ghrelin plasma concentrations, mesolimbic cue reactivity and alcohol craving was assessed by performing correlation and mediation analyses. Alcohol-induced brain response in a network of brain clusters, including the right and left ventral striatum, showed a significant positive association with acylated ghrelin plasma concentration. Additionally, acylated ghrelin was significantly associated with craving. Mediation analyses showed that the association between acylated ghrelin plasma concentration and alcohol craving is mediated by a cue-induced brain response in the ventral striatum. Based on the finding that ghrelin modulates mesolimbic reactivity to alcohol cues, the following should be considered: If alcohol craving and the appetitive status were interrelated, this has to be taken into account when implementing fMRI studies for addictive disorders. Moreover, appetite regulation seems to represent a valid treatment target for reducing cue reactivity in addictive disorders.

Total and acylated ghrelin plasma levels as potential long-term response markers in alcohol-dependent patients receiving high-dose of the GABA-B receptor agonist baclofen

The orexigenic hormone ghrelin is involved in the regulation of food intake and energy balance. Previous findings suggest its involvement in the modulation of mesolimbic reward pathways, thus potentially being relevant in the pathophysiology of substance use disorders such as alcohol dependence. In the present study, we assessed plasma levels of total and acylated ghrelin within the BACLAD trial, where alcohol-dependent patients received individually titrated high-dose baclofen (30-270 mg/d) within a randomized, placebo-controlled design. Plasma levels of total ghrelin and acylated ghrelin were measured at baseline, during treatment with individually titrated high-dose baclofen and after termination of the study medication within a timeframe of up to 20 weeks. Multivariate longitudinal non-parametric analysis revealed that plasma levels of total ghrelin significantly decreased in the group of abstinent patients receiving high-dose baclofen. In addition, plasma levels of total ghrelin correlated negatively with days of abstinence during treatment with high-dose baclofen. Plasma levels of acylated ghrelin increased during the study in the group of relapsed patients under baclofen and placebo treatment. These findings suggest that the long-term response to baclofen treatment in alcohol use disorder (AUD) might be monitored by assessing total and acylated ghrelin plasma levels.

Stress and Addiction: When a Robust Stress Response Indicates Resiliency

OBJECTIVE

Stress reactivity research has traditionally focused on the idea that exaggerated responses to stress may have adverse effects on health. Accumulating evidence suggests that attenuated responses to stress and delayed recovery may also be problematic.

METHODS

This review focuses on the role of the stress response of the hypothalamic-pituitary-adrenocortical axis, the endogenous opioid system, and the cardiovascular system in hypertension, pain perception, and addictive behaviors. Results from multiple methods of assessment and stress paradigms conducted in our laboratory over the past two decades are integrated with research from other investigators and with existing theories.

RESULTS

Research indicates that exaggerated biological and physiological responses to stress and attenuated pain perception are associated with hypertension and risk for cardiovascular diseases. This research complements work linking reduced stress responses with enhanced pain sensitivity and discomfort. Multiple studies have also demonstrated that an attenuated stress response is linked to exacerbation of withdrawal symptoms and relapse in nicotine addiction. Evidence indicates important moderators (i.e., sex, personality traits, and early life adversity) and hypothalamic-pituitary-adrenocortical- and endogenous opioid system-related mechanisms in the altered response to stress. I integrate these findings in a conceptual model emphasizing that robust stress responses in the context of addiction and relapse should be considered as a marker of resiliency.

CONCLUSIONS

A blunted stress response may indicate long-term physiological dysregulation that could usher harmful consequences for cardiovascular disease, pain perception, and addictive disorders. The impact of dysregulation is influenced by multiple individual and situational factors that should be considered in evaluating the clinical significance of stress response dysregulation.

Drinking water to reduce alcohol craving? A randomized controlled study on the impact of ghrelin in mediating the effects of forced water intake in alcohol addiction

BACKGROUND

Recent data suggest that ghrelin is involved in the pathophysiology of alcohol use disorders, affecting alcohol self-administration and craving. Gastric ghrelin secretion is reduced by stomach distension. We now tested the hypothesis whether the clinically well-known effects of high-volume water intake on craving reduction in alcoholism is mediated by acute changes in ghrelin secretion.

METHODS

In this randomized human laboratory study, we included 23 alcohol-dependent male inpatient subjects who underwent alcohol cue exposure. Participants of the intervention group drank 1000ml of mineral water within 10min directly thereafter, compared to the participants of the control group who did not. Craving and plasma concentrations of acetylated ghrelin were measured ten times during the 120min following the alcohol cue exposure session.

RESULTS

In the intervention group, a significant decrease in acetylated ghrelin in plasma compared to the control group was observed. This decrease was correlated to a reduction in patients' subjective level of craving. In the control group, no decrease of acetylated ghrelin in plasma and no association between alcohol craving and changes in plasma concentrations of acetylated ghrelin were observed.

CONCLUSIONS

Our results present new evidence that the modulation in the ghrelin system by oral water intake mediates the effects of volume intake with craving reduction in alcohol use disorders. Hence, in addition to pharmacological interventions with ghrelin antagonists, the reduction of physiological ghrelin secretion might be a target for future interventions in the treatment of alcohol craving.

The Role of the Ghrelin System in Drug Addiction

In the past years, a significant volume of research has implicated the appetitive hormone ghrelin in the mechanisms underlying drug use and addiction. From a neuroscientific standpoint, ghrelin modulates both reward and stress pathways, two key drivers of substance use behaviors. Previous investigations support a connection between the ghrelin system and alcohol, stimulants, and tobacco use in both animals and humans, while the research on opioids and cannabis is scarce. In general, upregulation of the ghrelin system seems to enhance craving for drugs as well as substances use. On the other hand, acute and chronic exposure to drugs of abuse influences the ghrelin system at different levels. This chapter summarizes the literature on the relationship between the ghrelin system and substance-related behaviors. We also review recent work investigating the ghrelin system as a potential pharmacological target for treating substance use disorders and discuss the need for additional research.

Changes in circulating peptide YY and ghrelin are associated with early smoking relapse

Ghrelin and peptide YY (PYY) during ad libitum smoking have been associated with decreased reported craving (ghrelin) and increased positive affect (PYY), and higher baseline ghrelin levels predicted subsequent increased risk of smoking relapse. The current study assessed PYY and ghrelin during ad libitum smoking and again after the initial 48h of a smoking cessation attempt. The data compared smokers who abstained for 28days (n=37), smokers who relapsed (n=54), and nonsmokers (n=37). Plasma samples and subjective measures assessing craving and mood were collected at the beginning of each session. Results showed that relapsers experienced greater levels of distress (ps <0.01). While nonsmokers and abstainers showed no change in ghrelin across the initial 48h, relapsers declined (p <0.01). With PYY, relapsers increased (p <0.05) across the early abstinent phase. PYY and ghrelin may be useful predictors of relapse, specifically in reference to early withdrawal.

Serum NUCB2/nesfatin-1 levels in different stages of alcohol dependence: Is there a relationship with craving?

INTRODUCTION

In the literature, the relationship between appetite regulating peptides and alcohol craving is on the debate.

AIM

This study aims to investigate serum level of NUCB2/nesfatin-1, which is discovered as appetite-related neuropeptide, in patients with alcohol dependence who were in craving and abstaining phase and to compare with healthy controls.

SETTINGS AND DESIGN

Research, Treatment, and Training Center for Alcohol and Substance Dependence, (AMATEM) Bakirkoy Training and Research Hospital for Psychiatry Neurology and Neurosurgery, Istanbul, case-control and prospective study design were used.

STATISTICAL ANALYSIS

Chi-square, Mann-Whitney U, paired samples, independent samples t- and Pearson correlation tests were used for analysis.

MATERIALS AND METHODS

Forty-three patients with alcohol dependence who have been admitted for detoxification and thirty healthy controls were included in the study. The blood samples were drawn after the 1^st day of admission and postdetoxification treatment in inpatients who reached to abstinence period and from 30 healthy controls. The Penn Alcohol Craving Scale and the Obsessive Compulsive Drinking Scale were applied to detect craving scores.

RESULTS

Initial serum NUCB2/nesfatin-1 levels in patients were significantly lower than in the healthy control group (P < 0.001). The NUCB2/nesfatin-1 level of initial phase was significantly lower than abstinence phase (P = 0.027). No correlation was found between craving scores and NUCB2/nesfatin-1 level (P > 0.05).

CONCLUSION

This study is the first that showed significant differences of serum NUCB2/nesfatin-1 level according to different stages of alcohol dependence. Plasma NUCB2/nesfatin-1 levels were lower in highest craving phase and tended to normalize after abstinence. Since we could not find a correlation between craving and NUCB2/nesfatin-1 levels, the increase of NUCB2/nesfatin-1 in abstinence phase might have been resulted from other reasons apart from craving.

The metabolic syndrome in patients with alcohol dependency: Current research and clinical implications

The relationship between alcohol dependency and disorders such as liver disease and cancer has been thoroughly researched. However, the effects of alcohol on cardiometabolic health remain controversial. Several reports found low to moderate alcohol consumption to be associated with a lower risk for cardiometabolic disorders. In contrast, excessive alcohol consumption has been related to an increased risk. Most of these studies were performed in non-clinical populations, therefore limiting the explanatory power to non-dependent patients. Only a few studies examined cardiovascular disorders and cardiovascular risk factors, in particular the metabolic syndrome (MetS), in alcohol dependent patients. We here present a narrative review of studies performed so far on the MetS in alcohol dependency, and provide current hypotheses on the association of alcohol dependency, appetite regulation and the development of the MetS.

Genetic variation of the growth hormone secretagogue receptor gene is associated with alcohol use disorders identification test scores and smoking

The multifaceted gut‐brain peptide ghrelin and its receptor (GHSR‐1a) are implicated in mechanisms regulating not only the energy balance but also the reward circuitry. In our pre‐clinical models, we have shown that ghrelin increases whereas GHSR‐1a antagonists decrease alcohol consumption and the motivation to consume alcohol in rodents. Moreover, ghrelin signaling is required for the rewarding properties of addictive drugs including alcohol and nicotine in rodents. Given the hereditary component underlying addictive behaviors and disorders, we sought to investigate whether single nucleotide polymorphisms (SNPs) located in the pre‐proghrelin gene (GHRL) and GHSR‐1a gene (GHSR) are associated with alcohol use, measured by the alcohol use disorders identification test (AUDIT) and smoking. Two SNPs located in GHRL, rs4684677 (Gln90Leu) and rs696217 (Leu72Met), and one in GHSR, rs2948694, were genotyped in a subset (n = 4161) of a Finnish population‐based cohort, the Genetics of Sexuality and Aggression project. The effect of these SNPs on AUDIT scores and smoking was investigated using linear and logistic regressions, respectively. We found that the minor allele of the rs2948694 SNP was nominally associated with higher AUDIT scores (P = 0.0204, recessive model) and smoking (P = 0.0002, dominant model). Furthermore, post hoc analyses showed that this risk allele was also associated with increased likelihood of having high level of alcohol problems as determined by AUDIT scores ≥ 16 (P = 0.0043, recessive model). These convergent findings lend further support for the hypothesized involvement of ghrelin signaling in addictive disorders.

DNA methylation of the LEP gene is associated with craving during alcohol withdrawal

Different studies have described evidence for an association between leptin serum levels and craving in alcohol dependent patients. As leptin expression is regulated by DNA methylation we investigated changes of DNA methylation of the LEP gene promoter region in alcohol dependent patients undergoing withdrawal. Results show that low methylation status is associated with increasing serum leptin levels and elevation of craving for alcohol in the referring patients group. These findings point towards a pathophysiological relevance of changes in DNA methylation of the LEP gene promoter region in alcohol dependence.

Peripherally circulating ghrelin does not mediate alcohol-induced reward and alcohol intake in rodents

BACKGROUND

Development of alcohol dependence, a chronic and relapsing disease, largely depends on the effects of alcohol on the brain reward systems. By elucidating the mechanisms involved in alcohol use disorder, novel treatment strategies may be developed. Ghrelin, the endogenous ligand for the growth hormone secretagogue receptor 1A, acts as an important regulator of energy balance. Recently ghrelin and its receptor were shown to mediate alcohol reward and to control alcohol consumption in rodents. However, the role of central versus peripheral ghrelin for alcohol reward needs to be elucidated.

METHODS

Given that ghrelin mainly is produced by peripheral organs, the present study was designed to investigate the role of circulating endogenous ghelin for alcohol reward and for alcohol intake in rodents.

RESULTS

We showed that the Spiegelmer NOX-B11-2, which binds and neutralizes acylated ghrelin in the periphery with high affinity and thus prevents its brain access, does not attenuate the alcohol-induced locomotor activity, accumbal dopamine release and expression of conditioned place preference in mice. Moreover, NOX-B11-2 does not affect alcohol intake using the intermittent access 20% alcohol 2-bottle-choice drinking paradigm in rats, suggesting that circulating ghrelin does not regulate alcohol intake or the rewarding properties of alcohol. In the present study, we showed however, that NOX-B11-2 reduced food intake in rats supporting a role for circulating ghrelin as physiological regulators of food intake. Moreover, NOX-B11-2 did not affect the blood alcohol concentration in mice.

CONCLUSIONS

Collectively, the past and present studies suggest that central, rather than peripheral, ghrelin signaling may be a potential target for pharmacological treatment of alcohol dependence.

Association of V89L SRD5A2 polymorphism with craving and serum leptin levels in male alcohol addicts

RATIONALE

A causal role of sex hormones in the onset and course of alcohol dependence is well established. We recently demonstrated that the genetics of the androgen receptor and aromatase relate to craving in alcohol addicts during withdrawal. This relationship involves the modulation of leptin, which affects the mesolimbic dopamine reward circuit. The steroid 5-α reductase 2 (SRD5A2) converts testosterone to dihydrotestosterone and thereby causes increased androgenic potency.

OBJECTIVES

In this study, we explored whether functionally relevant genetic polymorphisms in SRD5A2 (V89L, A49T, [TA](n)) are linked to alcohol addiction and craving.

METHODS AND RESULTS

We investigated 118 male alcohol-addicted inpatients admitted for withdrawal treatment and compared them to 50 healthy age- and body mass index-matched controls. The two groups did not differ in their allelic distributions. Subsequent analyses revealed an association between the V89L genotype and alcohol craving within the patient group (p < 0.05). Leptin accounted for 55 % of this relationship. Compared to VL and VV carriers, LL carriers had reduced serum leptin levels (p < 0.05) and lower levels of craving (p < 0.01). Furthermore, we observed an interaction between the V89L and the TTTAn aromatase polymorphisms (p < 0.05). No effects were found for A49T or (TA)(n).

CONCLUSIONS

These findings further support a crucial role of sex hormone biosynthetic genes and signaling in alcohol withdrawal. Craving is an accepted risk factor for alcohol relapse. Hence, these results might be helpful in predicting the outcomes of alcohol addicts after detoxification. With SRD5A2 inhibitors already in clinical use worldwide, this study may also guide future preventive and therapeutic strategies.

The relationship of appetitive, reproductive and posterior pituitary hormones to alcoholism and craving in humans

A significant challenge for understanding alcoholism lies in discovering why some, but not other individuals, become dependent on alcohol. Genetic, environmental, cultural, developmental, and neurobiological influences are recognized as essential factors underlying a person's risk for becoming alcohol dependent (AD); however, the neurobiological processes that trigger this vulnerability are still poorly understood. Hormones are important in the regulation of many functions and several hormones are strongly associated with alcohol use. While medical consequences are important, the primary focus of this review is on the underlying confluence of appetitive/feeding, reproductive and posterior pituitary hormones associated with distinct phases of alcoholism or assessed by alcohol craving in humans. While these hormones are of diverse origin, the involvement with alcoholism by these hormone systems is unmistakable, and demonstrates the complexity of interactions with alcohol and the difficulty of successfully pursuing effective treatments. Whether alcohol associated changes in the activity of certain hormones are the result of alcohol use or are the result of an underlying predisposition for alcoholism, or a combination of both, is currently of great scientific interest. The evidence we present in this review suggests that appetitive hormones may be markers as they appear involved in alcohol dependence and craving, that reproductive hormones provide an example of the consequences of drinking and are affected by alcohol, and that posterior pituitary hormones have potential for being targets for treatment. A better understanding of the nature of these associations may contribute to diagnosing and more comprehensively treating alcoholism. Pharmacotherapies that take advantage of our new understanding of hormones, their receptors, or their potential relationship to craving may shed light on the treatment of this disorder.

Low plasma adiponectin levels in panic disorder

BACKGROUND

The present study was performed to evaluate plasma adiponectin levels in the patients with PD.

METHOD

The study group included a total of 28 patients (17 females, 11 males) and 23 age- and sex-matched healthy comparison subjects (10 females and 13 males). The plasma fasting glucose, total cholesterol, triglyceride, low density lipoprotein (LDL), high density lipoprotein (HDL), and hemoglobin were measured.

RESULTS

There were no differences in regard to plasma fasting glucose, total cholesterol, triglyceride, LDL, HDL, and hemoglobin levels between groups. However, the mean adiponectin levels were significantly lower in the patient group (26.96 ± 9.92 ng/ml) compared to controls (37.63 ± 23.17 ng/ml) (t=-2.21; p=0.032). As for the ANCOVA analyses, it revealed the main effect of diagnosis on adiponectin levels (F=5.78, p=0.020) after BMI (body mass index) and gender as covariates.

CONCLUSIONS

Consequently, the findings of our study suggest that there may be an interaction between panic disorder and plasma adiponectin. Moreover, they led us to consider that these patients should be also followed as cardiac problems.

The association of the appetitive peptide acetylated ghrelin with alcohol craving in early abstinent alcohol dependent individuals

OBJECTIVE

Recent preclinical and clinical studies suggested ghrelin to have an orexigenic role in regulating appetite and energy balance. Preclinical studies also provided support for an important role of ghrelin in the neurobiology of addiction-related reward pathways, affecting the self-administration of alcohol and drugs as well as conditioned place preference. In contrast, clinical data have until now failed to support an association between ghrelin and alcohol craving, possibly due to the fact that these studies have analyzed the pharmacologically inactive, preprohormone ghrelin instead of ghrelin in its active, acetylated form.

MATERIALS AND METHODS

Our study sample was a group of 61 alcohol-dependent male inpatients. We assessed their plasma concentrations of both active and total ghrelin, using blood samples taken twice during the study: once at the onset of withdrawal, 12-24h after admission, and then again after 14 days of controlled abstinence. During this time, we also assessed the patients' alcohol cravings (applying the obsessive compulsive drinking scale, or OCDS), symptoms of depression (Beck Depression Inventory; BDI) and anxiety (State Trait Anxiety Inventory; STAI). The severity of alcohol dependence was assessed using the alcohol dependence scale (ADS).

RESULTS

We found a significant positive correlation between the plasma concentration of active ghrelin and alcohol craving in both blood samples. Plasma concentrations of active ghrelin increased significantly during early abstinence. In a linear regression model, the plasma concentration of active ghrelin on day one, the scores of the ADS, and the BDI explained 36% of the variance in OCDS sum score (p<0.0001). By day 14, these same factors accounted for 54% (p<0.0001). We did not detect any association between the plasma concentration of total ghrelin and patients' alcohol cravings.

CONCLUSION

Our results suggest that biologically active, acetylated ghrelin is involved in reward-associated craving during alcohol withdrawal and early abstinence in alcohol-dependent patients. Antagonizing ghrelin at its central growth-hormone secretagogue receptors (GHS-R1A) in the ventral tegmental area (VTA) may prove to be a novel pharmacological target in a future treatment for craving and relapse in alcoholics.

Ghrelin system in alcohol-dependent subjects: role of plasma ghrelin levels in alcohol drinking and craving

Animal studies suggest that the gut-brain peptide ghrelin plays an important role in the neurobiology of alcohol dependence (AD). Human studies show an effect of alcohol on ghrelin levels and a correlation between ghrelin levels and alcohol craving in alcoholics. This investigation consisted of two studies. Study 1 was a 12-week study with alcohol-dependent subjects, where plasma ghrelin determinations were assessed four times (T0-T3) and related to alcohol intake and craving [Penn Alcohol Craving Score (PACS) and Obsessive Compulsive Drinking Scale (OCDS)]. Serum growth hormone levels and assessment of the nutritional/metabolic status were also performed. Study 2 was a pilot case-control study to assess ghrelin gene polymorphisms (Arg51Gln and Leu72Met) in alcohol-dependent individuals. Study 1 showed no significant differences in ghrelin levels in the whole sample, while there was a statistical difference for ghrelin between non-abstinent and abstinent subjects. Baseline ghrelin levels were significantly and positively correlated with the PACS score at T1 and with all craving scores both at T2 and T3 (PACS, OCDS, obsessive and compulsive OCDS subscores). In Study 2, although there was a higher frequency of the Leu72Met ghrelin gene polymorphism in alcohol-dependent individuals, the distribution between healthy controls and alcohol dependent individuals was not statistically significant. This investigation suggests that ghrelin is potentially able to affect alcohol-seeking behaviors, such as alcohol drinking and craving, representing a new potential neuropharmacological target for AD.

Biological mechanisms in alcohol dependence--new perspectives

Neurobiological research in alcohol dependence has led to a new understanding of this addictive disease. While some important mechanisms like alterations in the mesolimbic reward system or changes in the hypothalamus-pituitary-adrenocortical axis have been well studied, other possible neurobiological mechanisms are still unrevealed. This applies for the role of specific neuroendocrinological pathways like the appetite-regulating system and the modification of gene expression, particularly the influence of genetic variants of transcription factors or epigenetic mechanism like DNA methylation or histone acetylation. This review describes the current knowledge regarding these factors, focusing particularly on the role of appetite- and volume-regulating hormones, the role of genetic variants of specific transcription factors and the function of epigenetic alterations in the genomic sequence of candidate genes for alcohol dependence. A further understanding of the influence of transcription factors and epigenetic regulation may help to elucidate the pathophysiological mechanisms in the neurobiology of alcohol dependence.

Ghrelin receptor (GHS-R1A) antagonism suppresses both operant alcohol self-administration and high alcohol consumption in rats

The mechanisms involved in alcohol use disorders are complex. It has been shown that ghrelin is an important signal for the control of body weight homeostasis, preferably by interacting with hypothalamic circuits, as well as for drug reward by activating the mesolimbic dopamine system. The ghrelin receptor (GHS-R1A) has been shown to be required for alcohol-induced reward. Additionally, ghrelin increases and GHR-R1A antagonists reduce moderate alcohol consumption in mice, and a single nucleotide polymorphism in the GHS-R1A gene has been associated with high alcohol consumption in humans. However, the role of central ghrelin signaling in high alcohol consumption is not known. Therefore, the role of GHS-R1A in operant self-administration of alcohol in rats as well as for high alcohol consumption in Long-Evans rats and in alcohol preferring [Alko alcohol (AA)] rats was studied here. In the present study, the GHS-R1A antagonist, JMV2959, was found to reduce the operant self-administration of alcohol in rats and to decrease high alcohol intake in Long-Evans rats as well as in AA rats. These results suggest that the ghrelin receptor signaling system, specifically GHS-R1A, is required for operant self-administration of alcohol and for high alcohol intake in rats. Therefore, the GHS-R1A may be a therapeutic target for treatment of addictive behaviors, such as alcohol dependence.

Association between leptin levels and doses of clomethiazole during alcohol withdrawal: a pilot study

AIMS

The issue of leptin as a putative state marker of alcohol use and its role in craving has been raised in the last few years. Recently, a strong GABA-ergic modulation of leptin was postulated. The aim of the pilot study was to examine leptin levels in correlation with the strongly GABA-mimetic active substance clomethiazole. The main hypothesis was that higher doses of the strong GABA-mimetic clomethiazole are positively correlated with higher leptin levels.

METHODS

Twenty-eight alcohol-dependent patients (3 females, median age 36 years) undergoing alcohol withdrawal were included. In 18 patients with and 10 without clomethiazole, serum leptin was analyzed at day 1 and day 7 of alcohol withdrawal. Both groups did not differ by age, BMI, or alcohol use characteristics.

RESULTS

In the clomethiazole group, significant correlations were found between leptin levels at day 1 and clomethiazole dose (p = 0.004), clomethiazole and leptin at day 1/BMI (p = 0.009) and leptin at day 1 and clomethiazole/body surface (p = 0.006). Furthermore, patients with higher clomethiazole doses demonstrated significant higher leptin levels at day 1 (p = 0.044) and day 7 (p = 0.046).

CONCLUSIONS

Our pilot data show a strong association between leptin levels and clomethiazole doses, thus supporting further research.

Ghrelin receptor antagonism attenuates nicotine-induced locomotor stimulation, accumbal dopamine release and conditioned place preference in mice

BACKGROUND

The orexigenic peptide ghrelin activates the reward systems, specifically the cholinergic-dopaminergic reward link, suggesting that ghrelin may increase the incentive salience of motivated behaviours such as food seeking. Moreover, central ghrelin signalling, involving the growth hormone secretagogue receptor 1A (GHS-R1A), is required for the rewarding properties, as measured by locomotor stimulation, accumbal dopamine release and conditioned place preference, of alcohol, cocaine as well as amphetamine. As the target circuits for other drugs of abuse, including nicotine, in the brain includes this reward link, we sought to determine whether the central ghrelin signalling system is involved in nicotine's activation of this system.

METHODS

This was investigated by studying the effects of peripheral administration of a GHS-R1A antagonist (JMV2959) on the nicotine-induced locomotor simulation, accumbal dopamine release and conditioned place preference.

RESULTS

In the present study we found that the ability of nicotine to increase the locomotor activity, accumbal dopamine release and to condition place preference were reduced in mice treated with a GHS-R1A antagonist.

CONCLUSION

Thus GHS-R1A appears to be required not only for alcohol, cocaine and amphetamine-induced reward, but also for reward induced by nicotine. Our data suggest that the central ghrelin signalling system may constitute a novel potential target for treatment of drug dependence.

The role of the central ghrelin system in reward from food and chemical drugs

Here we review recent advances that identify a role for the central ghrelin signalling system in reward from both natural rewards (such as food) and artificial rewards (that include alcohol and drugs of abuse). Whereas ghrelin emerged as a stomach-derived hormone involved in energy balance, hunger and meal initiation via hypothalamic circuits, it now seems clear that it also has a role in motivated reward-driven behaviours via activation of the so-called "cholinergic-dopaminergic reward link". This reward link comprises a dopamine projection from the ventral tegmental area (VTA) to the nucleus accumbens together with a cholinergic input, arising primarily from the laterodorsal tegmental area. Ghrelin administration into the VTA or LDTg activates the "cholinergic-dopaminergic" reward link, suggesting that ghrelin may increase the incentive value of motivated behaviours such as reward-seeking behaviour ("wanting" or "incentive motivation"). Further, direct injection of ghrelin into the brain ventricles or into the VTA increases the consumption of rewarding foods as well as alcohol in mice and rats. Studies in rodents show beneficial effects of ghrelin receptor (GHS-R1A) antagonists to suppress the intake of palatable food, to reduce preference for caloric foods, to suppress food reward and motivated behaviour for food. They have also been shown to reduce alcohol consumption, suppress reward induced by alcohol, cocaine and amphetamine. Furthermore, variations in the GHS-R1A and pro-ghrelin genes have been associated with high alcohol consumption, smoking and increased weight gain in alcohol dependent individuals as well as with bulimia nervosa and obesity. Thus, the central ghrelin signalling system interfaces neurobiological circuits involved in reward from food as well as chemical drugs; agents that directly or indirectly suppress this system emerge as potential candidate drugs for suppressing problematic over-eating that leads to obesity as well as for the treatment of substance use disorder.

The alcohol-induced locomotor stimulation and accumbal dopamine release is suppressed in ghrelin knockout mice

Ghrelin, the first endogenous ligand for the type 1A growth hormone secretagogue receptor (GHS-R1A), plays a role in energy balance, feeding behavior, and reward. Previously, we showed that pharmacologic and genetic suppression of the GHS-R1A attenuates the alcohol-induced stimulation, accumbal dopamine release, and conditioned place preference as well as alcohol consumption in mice, implying that the GHS-R1A is required for alcohol reward. The present study further elucidates the role of ghrelin for alcohol-induced dopamine release in nucleus accumbens and locomotor stimulation by means of ghrelin knockout mice. We found that the ability of alcohol to increase accumbal dopamine release in wild-type mice is not observed in ghrelin knockout mice. Furthermore, alcohol induced a locomotor stimulation in the wild-type mice and ghrelin knockout mice; however, the locomotor stimulation in homozygote mice was significantly lower than in the wild-type mice. The present series of experiments suggest that endogenous ghrelin may be required for the ability of alcohol to activate the mesolimbic dopamine system.

Expression of the gene encoding the ghrelin receptor in rats selected for differential alcohol preference

The mechanisms involved in alcohol use disorder, a chronic relapsing brain disorder, are complex and involve various signalling systems in the brain. Recently, the orexigenic peptide ghrelin was shown to be required for alcohol-induced reward, an effect mediated via ghrelin receptors, GHS-R1A, at the level of the cholinergic-dopaminergic reward link. Moreover, ghrelin increases and GHR-R1A antagonists reduce moderate alcohol consumption in mice, and a single nucleotide polymorphism in the GHS-R1A gene has been associated with high alcohol consumption in humans. Therefore, GHS-R1A gene expression and alcohol intake were investigated in high, AA (Alko, Alcohol), versus low, ANA (Alko, Non-Alcohol), alcohol consuming rats as well as in Wistar rats. In the AA and ANA rats plasma ghrelin levels were also measured. GHS-R1A gene expression was increased in AA compared to ANA rats in nucleus accumbens, ventral tegmental area, amygdala, prefrontal cortex and hippocampus. A similar trend was observed in the ventral tegmental area of Wistar rats consuming high amounts of alcohol. Furthermore, the AA rats had significantly smaller reduction of plasma ghrelin levels over time, after several weeks of alcohol exposure, than had the ANA rats. The present study provides further evidence for that the ghrelin signalling system, in particular at the level of the mesocortocolimbic dopamine system, is involved in alcohol consumption, and thus possibly contributes to alcohol use disorder. Therefore the GHS-R1A may constitute a novel candidate for development of new treatment strategies for alcohol dependence.

Role of feeding-related pathways in alcohol dependence: A focus on sweet preference, NPY, and ghrelin

Converging research evidence suggests that alcohol and food-seeking behaviors share common neural pathways. There is preclinical and clinical evidence linking the consumption of sweets to alcohol intake in both animals and humans. In addition, a growing body of animal and human literature suggests the involvement of "feeding-related" peptides in alcohol-seeking behavior. In particular, both central and peripheral appetitive peptides have shown a possible role in alcohol dependence. The present mini-review will summarize the literature on the link between sweet preference and alcohol dependence, and on the role of feeding-related peptides in alcohol dependence. Specifically, in an attempt to narrow the field, the present mini-review will focus on 2 specific pathways, the central neuropeptide Y and the peripheral gut peptide ghrelin. Although more research is needed, data available suggest that studying feeding-related pathways in alcohol dependence may have theoretic, biologic, diagnostic, and therapeutic implications.

Prevalence of the metabolic syndrome in men and women with alcohol dependence: results from a cross-sectional study during behavioural treatment in a controlled environment

AIMS

Prevalence of metabolic syndrome (MetS) in men and women who use alcohol has been inconsistent in the literature. The aim of this study is to compare the prevalence of MetS in patients with a diagnosis of alcohol dependence who are currently abstinent in a controlled environment, and in control subjects followed in primary care from a similar region in Northern Germany.

DESIGN

Cross-sectional study.

SETTING

In-patient cognitive behavioural therapy.

PARTICIPANTS

One hundred and ninety-seven men and women with alcohol dependence during behavioural treatment in a controlled environment were compared to 1158 subjects from primary care from a similar region in northern Germany.

MEASUREMENTS

We used the American Heart Association/National Heart, Lung and Blood Institute (AHA/NHBLI) criteria to determine the rate of MetS and each single criterion of MetS in both groups.

FINDINGS

The prevalence of MetS was almost twice as high in men and women with alcohol dependence compared to control subjects (30.6% versus 17.0%). With respect to the single criteria, elevations were found for fasting glucose and blood pressure in both genders and for triglycerides in women only. High density lipoprotein (HDL)-cholesterol was higher in men and women with alcohol dependence.

CONCLUSIONS

Our results demonstrate an increased rate of MetS, increased blood pressure and dysregulation of glucose and lipid metabolism in alcohol-dependent patients. Whether high HDL-cholesterol has cardioprotective effects in this context remain doubtful.

Ghrelin receptor antagonism attenuates cocaine- and amphetamine-induced locomotor stimulation, accumbal dopamine release, and conditioned place preference

INTRODUCTION

Recently we demonstrated that genetic or pharmacological suppression of the central ghrelin signaling system, involving the growth hormone secretagogue receptor 1A (GHS-R1A), lead to a reduced reward profile from alcohol. As the target circuits for ghrelin in the brain include a mesolimbic reward pathway that is intimately associated with reward-seeking behaviour, we sought to determine whether the central ghrelin signaling system is required for reward from drugs of abuse other than alcohol, namely cocaine or amphetamine.

RESULTS

We found that amphetamine-as well as cocaine-induced locomotor stimulation and accumbal dopamine release were reduced in mice treated with a GHS-R1A antagonist. Moreover, the ability of these drugs to condition a place preference was also attenuated by the GHS-R1A antagonist.

CONCLUSIONS

Thus GHS-R1A appears to be required not only for alcohol-induced reward, but also for reward induced by psychostimulant drugs. Our data suggest that the central ghrelin signaling system constitutes a novel potential target for treatment of addictive behaviours such as drug dependence.

The modulating effect of the androgen receptor on craving in alcohol withdrawal of men is partially mediated by leptin

We reported recently that a functional relevant CAG trinucleotide repeat of the androgen receptor influences craving of men in alcohol withdrawal. It is known to modulate serum concentrations of leptin, which affects hypothalamic appetite regulation. Its plasma levels are elevated during chronic alcohol consumption, normalize within periods of abstinence and are associated with craving. The aim of this study was to further elucidate the role of leptin in mediating the effects of the mentioned polymorphism on craving in men undergoing alcohol withdrawal. We included 110 male in-patients who were admitted for detoxification treatment. Each one had an established diagnosis of alcohol dependence according to the DSM-IV. Our results show on the one hand negative associations between the number of CAG repeats and (i) leptin serum levels (P<0.01) and (ii) craving (P<0.05), and on the other hand, a positive association between leptin and craving of man in alcohol withdrawal (P<0.001). The path analysis revealed direct and mediated effects of the number of CAG repeats on alcohol craving, direct effects (r=-0.144) accounting for 60% and indirect, leptin-mediated effects (r=-0.096) accounting for 40% of the total effect. Dysregulation of sexual hormones influences human metabolism and seems to affect leptin homeostasis. This report suggests that the investigated polymorphism mediates its effect on craving of men in alcohol withdrawal mostly through the regulation of leptin. Nevertheless future studies are needed to further explore the functionality of the androgen receptor gene in terms of craving.

Low plasma adiponectin levels in obsessive-compulsive disorder

This study was designed to examine plasma adiponectin levels in patients with obsessive-compulsive disorder (OCD). The plasma adiponectin and glucose concentrations were determined in 23 patients (13 females, 10 males) and age and sex-matched 23 healthy controls (14 females and 9 males). In measuring adiponectin levels, ELISA method was used. The mean adiponectin levels were 11.1+/-2.2 ng/ml for the patient group and 17.6+/-2.9 ng/ml for control group (P=0.00078). By using ANCOVA, significant difference in the mean adiponectin values continued after controlling for BMI or sex (F=6.04, P<0.013 adjusted for BMI; F=5.67, P<0.021 adjusted for sex). Despite some limitations, the present study suggests that there may be an interaction between OCD and plasma adiponectin. In this interaction, one should keep into mind both pathophysiologic dimension and cardiovascular vulnerability. But it is clear that although the present findings are of considerable significance they should be supported by the studies with larger sample.

Hormones and drinking behaviour: new findings on ghrelin, insulin, leptin and volume-regulating hormones. An ESBRA Symposium report

There is growing evidence for a role of appetite-related peptides and volume-regulating hormones in alcoholism. In particular, recent evidence has suggested that hormones, such as ghrelin, insulin and leptin and volume-regulating hormones, could play a role in alcohol-seeking behaviour. The goal of this review is to discuss the results of recent preclinical and clinical investigations on this topic. The findings indicate that neuroendocrinological mechanisms are potentially involved in the neurobiology of alcohol craving. Accordingly, research on this topic could lead to possible development of new therapeutic approaches in the treatment of patients with alcohol problems.

Requirement of central ghrelin signaling for alcohol reward

The stomach-derived hormone ghrelin interacts with key CNS circuits regulating energy balance and body weight. Here we provide evidence that the central ghrelin signaling system is required for alcohol reward. Central ghrelin administration (to brain ventricles or to tegmental areas involved in reward) increased alcohol intake in a 2-bottle (alcohol/water) free choice limited access paradigm in mice. By contrast, central or peripheral administration of ghrelin receptor (GHS-R1A) antagonists suppressed alcohol intake in this model. Alcohol-induced locomotor stimulation, accumbal dopamine release and conditioned place preference were abolished in models of suppressed central ghrelin signaling: GHS-R1A knockout mice and mice treated with 2 different GHS-R1A antagonists. Thus, central ghrelin signaling, via GHS-R1A, not only stimulates the reward system, but is also required for stimulation of that system by alcohol. Our data suggest that central ghrelin signaling constitutes a potential target for treatment of alcohol-related disorders.

Blood glucose level, alcohol heavy drinking, and alcohol craving during treatment for alcohol dependence: results from the Combined Pharmacotherapies and Behavioral Interventions for Alcohol Dependence (COMBINE) Study

BACKGROUND

Heavy drinking may increase blood glucose levels. Moreover, in alcohol-dependent subjects, glucose may play a putative role in alcohol preference.

METHODS

This study investigated the relationship between blood glucose levels and both alcohol heavy drinking and craving in alcohol-dependent subjects participating in the COMBINE Study. The primary objective was to evaluate the relationship between baseline (pretreatment) glucose levels and percentage of heavy drinking day (PHDD) during treatment. The secondary objective was to evaluate the relationship between glucose levels, baseline PHDD, and craving measured by the Obsessive Compulsive Drinking Scale (OCDS).

RESULTS

This analysis consisted of 1,324 participants. Baseline glucose levels were significantly and positively associated with PHDD during treatment [F(1, 1225) = 5.21, p = 0.023], after controlling for baseline PHDD [F(1, 1225) = 36.25, p < 0.0001], gender [F (1, 1225) = 3.33, p = 0.07], and body mass index (BMI) [F(1, 1225) = 0.31, p = 0.58]. Higher glucose levels at baseline were associated with a higher percentage of PHDD at pretreatment [F(1, 1304) = 5.96, p = 0.015], after controlling for gender [F(1, 1304) = 0.29, p = 0.59] and BMI [F(1, 1304) = 0.90, p = 0.34]. Glucose was not significantly associated with the OCDS total score [F(1, 1304) = 0.12, p = 0.73], the OCDS Obsessive subscale [F(1, 1304) = 0.35, p = 0.56], or the OCDS Compulsive subscale [F(1, 1304) = 1.19, p = 0.28] scores, after controlling for gender and BMI.

DISCUSSION

A link between pretreatment glucose levels and heavy drinking during treatment was found, suggesting a role of glucose in predicting heavy alcohol consumption. Although caution is needed in the interpretation of these results, elevated glucose and heavy drinking may be affected by a common mechanism and manipulations affecting glucose regulation may influence alcohol consumption.

Epigenetic regulation and gene expression of vasopressin and atrial natriuretic peptide in alcohol withdrawal

Disturbances of volume regulating peptides like vasopressin and atrial natriuretic peptide (ANP) have been described in early abstinent patients. Aim of the present study was to evaluate possible alterations of the promoter-related DNA methylation of the ANP and vasopressin precursor genes and the related mRNA-expression of these genes in early alcohol withdrawal. We analyzed blood samples of 57 healthy controls and of 111 patients suffering from alcohol dependence that were admitted for detoxification treatment. Promoter-related DNA methylation and mRNA-expression of vasopressin and ANP genes were assessed using real-time PCR. Vasopressin mRNA-expression was not statistically different between patients and controls. However, we found a significantly elevated promoter-related DNA methylation of the vasopressin gene in patients with alcohol dependence (Mann-Whitney U-test: Z=-2.178, p=0.029). ANP mRNA-expression was significantly elevated in alcoholic patients (Z=-6.240, p<0.001) while promoter-related DNA methylation of ANP was significantly decreased (Z=-2.282, p=0.023). Furthermore, promoter-related DNA methylation of ANP was significantly correlated to the extent of craving measured with the OCDS (r=-0.197, p=0.040). The findings of the present study show significant alterations of the mRNA-expression and promoter-related DNA methylation of vasopressin and especially ANP precursor genes in patients with alcohol dependence. Further studies focusing on longitudinal changes of epigenetic regulation and gene expression of both peptides are needed to clarify the pathophysiological role of these findings.