Insulin But Not Insulin Growth Factor-1 Correlates With Craving in Currently Drinking Alcohol-Dependent Patients

Circulating Immune and Endocrine Markers in Currently Drinking and Abstinent Individuals With Alcohol Use Disorder and Controls

Alcohol use disorder (AUD) is associated with changes in endocrine and immune system function. This study is a secondary analysis aimed at investigating changes in circulating immune and endocrine biomarkers in blood samples from three groups: (1) healthy controls (HC, N = 12), (2) AUD-currently drinking, nontreatment seeking (CD, N = 9), and (3) AUD-abstinent, treatment-seeking (AB, N = 10; abstinent for at least 6 weeks). We hypothesized that both immune and endocrine biomarker concentrations would be different in AUD groups compared to healthy controls. Immune biomarkers included IL-8, IL-18, CCL2, TNF-α, IL-1RA, IL-6, and IL-10. Endocrine biomarkers included brain-derived neurotrophic factor (BDNF), glucagon-like peptide 1 (GLP-1), ghrelin, gastric inhibitory peptide (GIP), growth hormone, leptin, and insulin. Biomarker concentrations were compared between the three groups while controlling for age and sex, and associations between biomarker concentrations and behavioral measures were explored. IL-8 concentrations were elevated in AB compared to CD and HC (F(2,29) = 6.33, p = 0.006, ƞp 2 = 0.318). BDNF concentrations were lower in AB compared to HC (F(2,30) = 4.34, p = 0.02, ƞp 2 = 0.266). GLP-1 concentrations were higher in AB compared to HC (F(2,25) = 4.22, p = 0.03, ƞp 2 = 0.287). Exploratory analyses in combined groups showed that measures of past drinking, AUD severity, and anxiety/depression positively correlated with IL-18 and TNF-α and negatively correlated with BDNF. These results demonstrate that circulating concentrations of both immune and endocrine proteins are altered in abstinent individuals with a history of severe AUD (AB group) compared to healthy controls. In contrast, no group differences were observed for any biomarker between the nontreatment seeking, currently drinking people with AUD and the HC group. Our findings highlight the importance of accounting for AUD severity, comorbidities, and treatment-seeking status, especially when studying alcohol-related biomarkers.

The crosstalk between fibroblast growth factor 21 (FGF21) system and substance use

Existing literature indicates that communication between the central nervous system and the peripheral nervous system is disrupted by substance use disorders (SUDs), including alcohol use disorder (AUD). Fibroblast growth factor 21 (FGF21), a liver-brain axis hormone governing energy homeostasis, has been shown to modulate alcohol intake/preference and other substances. To further elucidate the relationship between FGF21, alcohol use, and other substance use, we conducted a scoping review to explore the association between FGF21 and SUDs. Increases in FGF21 reduce alcohol consumption while suppressing FGF21 increases alcohol consumption, demonstrating an inverse relationship. Alcohol elevates FGF21 levels primarily via the liver, subsequently promoting neuronal signals to curb alcohol intake. FGF21 activation engages molecular pathways that defend against alcohol-induced fat accumulation, oxidative stress, and inflammation. Considering the bidirectional association between FGF21 and alcohol, further studies on the FGF21 system as a potential pharmacotherapy for AUD and alcohol-associated liver disease are warranted.

Perspectives on the pharmacological management of alcohol use disorder: Are the approved medications effective?

INTRODUCTION

In the last decades, many medications have been tested for the treatment of Alcohol Use Disorder (AUD). Among them, disulfiram, acamprosate, naltrexone, nalmefene, sodium oxybate and baclofen have been approved in different countries, with different specific indications. Topiramate is not approved for the treatment of AUD, however, it is suggested as a therapeutic option by the American Psychiatric Association for patients who do not tolerate or respond to approved therapies.

AREAS COVERED

In this narrative review we have analyzed the main studies available in literature, investigating the efficacy and safety of these medications, distinguishing whether they were oriented towards abstinence or not. Randomized controlled studies, analyzing larger populations for longer periods were the main focus of our analysis.

CONCLUSIONS

The medications currently available for the treatment of AUD are quite effective, yet further progress can still be achieved through the personalized strategies. Also, these medications are still markedly underutilized in clinical practice and many patients do not have access to specialized treatment.

Life-course effects of early life adversity exposure on eating behavior and metabolism

Environmental variations in early life influence brain development, making individuals more vulnerable to psychiatric and metabolic disorders. Early life stress (ELS) has a strong impact on the development of eating behavior. However, eating is a complex behavior, determined by an interaction between signals of energy homeostasis, neuronal circuits involved in its regulation, and circuits related to rewarding properties of the food. Although mechanisms underlying ELS-induced altered feeding behavior are not completely understood, evidence suggest that the effects of ELS on metabolic, mood, and emotional disorders, as well as reward system dysfunctions can contribute directly or indirectly to altered feeding behavior. The focus of this chapter is to discuss the effects of ELS on eating behavior and metabolism, considering different factors that control appetite such as energy homeostasis, hedonic properties of the food, emotional and cognitive status. After highlighting classic studies on the association between ELS and eating behavior alterations, we discuss how exposure to adversity can interact with genetics characteristics to predict variable outcomes.

Growth Factors and Alcohol Use Disorder

Neurotrophic growth factors were originally characterized for their support in neuronal differentiation, outgrowth, and survival during development. However, it has been acknowledged that they also play a vital role in the adult brain. Abnormalities in growth factors have been implicated in a variety of neurological and psychiatric disorders, including alcohol use disorder (AUD). This work focuses on the interaction between alcohol and growth factors. We review literature suggesting that several growth factors play a unique role in the regulation of alcohol consumption, and that breakdown in these growth factor systems is linked to the development of AUD. Specifically, we focus on the brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), fibroblast growth factor 2 (FGF2), and insulin growth factor 1 (IGF-1). We also review the literature on the potential role of midkine (MDK) and pleiotrophin (PTN) and their receptor, anaplastic lymphoma kinase (ALK), in AUD. We show that alcohol alters the expression of these growth factors or their receptors in brain regions previously implicated in addiction, and that manipulations on these growth factors and their downstream signaling can affect alcohol-drinking behaviors in animal models. We conclude that there is a need for translational and clinical research to assess the therapeutic potential of new pharmacotherapies targeting these systems.

Obsessive-compulsive disorder and growth factors: A comparative review

The goal of this article is to clarify the role of various growth factors in the establishment and progression of obsessive-compulsive disorder (OCD). OCD is a chronic mental disorder with recurrent intrusive thoughts and/or repetitive compulsive behaviors that increase during stressful periods. Growth and neurotrophic factors may be contributing factors in the pathophysiology of OCD. Many of them are synthesized and released within the central nervous system and act as trophic agents in neurons; some of them are involved in brain growth, development, neurogenesis, myelination and plasticity, while others take part in the protection of the nervous system following brain injuries. This paper attempts to identify all articles investigating the relationship between OCD and neurotrophic and growth factors, in both animal and human studies, with a focus on adult brain studies. Based on the PubMed and Scopus and Science Direct search tools, the available articles and studies are reviewed. Out of 230 records in total, the ones related to our review topic were taken into account to further understand the pathophysiological mechanism(s) of OCD, providing methods to improve its symptoms via the modification of neurotrophins and growth factor imbalances.

Red Bull® energy drink increases consumption of higher concentrations of alcohol

Mixing alcohol with caffeinated energy drinks is a common practice, especially among young people. In humans, the research on this issue has mainly focused on the use of the mass-marketed energy drinks themselves, whereas in animal models, it has focused on the individual effects of their active ingredients (i.e. caffeine). Here, we have characterized how Red Bull®, one of the most consumed caffeinated energy drink worldwide, modulates operant alcohol self-administration in Wistar rats. We found that animals readily and steadily responded for Red Bull (mean: 90 responses, 30 minutes and fixed-ratio 1), which was accompanied by locomotor stimulating effects (26 percent increase). The higher the concentration of alcohol (3-20 percent), the higher the consumption of alcohol (g/kg) and associated blood alcohol levels (91.76 percent) in the mixed Red Bull-alcohol group (60 percent increase). Blood caffeine levels in the Red Bull group were 4.69 μg/ml and 1.31 μg/ml in the Red Bull-alcohol group after the 30-minute session. Because Red Bull also contains 11 percent sucrose, we examined the time course of blood glucose as well as insulin and corticosterone. The correlation between intake of Red Bull and blood glucose levels was higher at 90 minutes than 5 minutes after its consumption, and there was no relationship with blood insulin or blood corticosterone levels. Red Bull did not alter extinction and reacquisition of responding for alcohol nor did it affect relapse-like drinking. Overall, our results suggest that Red Bull might be a vulnerability factor to develop alcoholism given that it intensifies the consumption of higher concentrations of alcohol.

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.

Decreased plasma concentrations of BDNF and IGF-1 in abstinent patients with alcohol use disorders

The identification of growth factors as potential biomarkers in alcohol addiction may help to understand underlying mechanisms associated with the pathogenesis of alcohol use disorders (AUDs). Previous studies have linked growth factors to neural plasticity in neurocognitive impairment and mental disorders. In order to further clarify the impact of chronic alcohol consumption on circulating growth factors, a cross-sectional study was performed in abstinent AUD patients (alcohol group, N = 91) and healthy control subjects (control group, N = 55) to examine plasma concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1) and IGF-1 binding protein-3 (IGFBP-3). The association of these plasma peptides with relevant AUD-related variables and psychiatric comorbidity was explored. The alcohol group was diagnosed with severe AUD and showed an average of 13 years of problematic use and 10 months of abstinence at the moment of participating in the study. Regarding common medical conditions associated with AUD, we observed an elevated incidence of alcohol-induced liver and pancreas diseases (18.7%) and psychiatric comorbidity (76.9%). Thus, AUD patients displayed a high prevalence of dual diagnosis (39.3%) [mainly depression (19.9%)] and comorbid substance use disorders (40.7%). Plasma BDNF and IGF-1 concentrations were significantly lower in the alcohol group than in the control group (p<0.001). Remarkably, there was a negative association between IGF-1 concentrations and age in the control group (r = -0.52, p<0.001) that was not found in the alcohol group. Concerning AUD-related variables, AUD patients with liver and pancreas diseases showed even lower concentrations of BDNF (p<0.05). In contrast, the changes in plasma concentrations of these peptides were not associated with abstinence, problematic use, AUD severity or lifetime psychiatric comorbidity. These results suggest that further research is necessary to elucidate the role of BDNF in alcohol-induced toxicity and the biological significance of the lack of correlation between age and plasma IGF-1 levels in abstinent AUD patients.

An integrated molecular landscape implicates the regulation of dendritic spine formation through insulin-related signalling in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder with onset in childhood and is characterized by obsessions (recurrent, intrusive, persistent thoughts, impulses and/or ideas that often cause anxiety or distress) and compulsions (ritualized and stereotypic behaviours or mental acts that are often performed to relieve anxiety or distress associated with obsessions). Although OCD is a heritable disorder, its complex molecular etiology is poorly understood.

METHODS

We combined enrichment analyses and an elaborate literature review of the top-ranked genes emerging from the 2 published genome-wide association studies of OCD and candidate genes implicated through other evidence in order to identify biological processes that, when dysregulated, increase the risk for OCD.

RESULTS

The resulting molecular protein landscape was enriched for proteins involved in regulating postsynaptic dendritic spine formation - and hence synaptic plasticity - through insulin-dependent molecular signalling cascades.

LIMITATIONS

This study is a first attempt to integrate molecuar information from different sources in order to identify biological mechanisms underlying OCD etiology. Our findings are constrained by the limited information from hypothesis-free studies and the incompleteness and existing limitations of the OCD literature and the gene function annotations of gene enrichment tools. As this study was solely based on in silico analyses, experimental validation of the provided hypotheses is warranted.

CONCLUSION

Our work suggests a key role for insulin and insulin-related signalling in OCD etiology and - if confirmed by independent studies - could eventually pave the way for the development of novel OCD treatments.

Serum Insulin Levels Are Reduced by Intravenous Ghrelin Administration but Do Not Correlate with Alcohol Craving in Alcohol-Dependent Individuals

BACKGROUND

Increasing evidence supports a role for appetite-regulating pathways like ghrelin, insulin, and leptin in alcoholism. We previously reported that intravenous (i.v.) exogenous ghrelin increases alcohol craving. We also reported i.v. ghrelin reduces endogenous serum leptin, whose levels, in turn, negatively correlated with alcohol craving. Exogenous ghrelin administration decreases insulin secretion both in vitro and in vivo experiments. This study tested the hypothesis that i.v. ghrelin may also decrease endogenous serum insulin levels in alcoholic individuals. Additionally, we explored possible correlations between serum insulin and alcohol craving, since a correlation between insulin and alcohol craving was previously reported.

METHODS

This was a double-blind, placebo-controlled human laboratory study ( n =43). Non-treatment-seeking, alcohol-dependent, heavy drinkers were randomized to receive i.v. ghrelin or placebo, followed by an alcohol cue-reactivity procedure.

RESULTS

There was a main effect for i.v. ghrelin, compared to placebo in reducing serum insulin ( P <.05). There was also a time effect ( P <.001) but not ghrelin x time interaction ( P >.05). We did not find a correlation between the reduction of serum insulin and alcohol craving ( P >.05). The change in serum insulin was consistent with a parallel reduction in serum connective-peptide in the ghrelin group compared with placebo, although this difference did not reach statistical significance ( P =.076). No similar effects were found for other glucose-regulating hormones analyzed i.e. glucagon, glucagon-like peptide-1, and gastric inhibitory peptide ( P s>.05).

CONCLUSIONS

These findings indicate i.v. ghrelin administration has an effect on reducing serum insulin in alcohol-dependent individuals; however, the reduction of insulin did not correlate with changes in alcohol cue-elicited craving. We speculate that, unlike for leptin, the interactions between ghrelin and insulin relationship are limited at the peripheral level. However, mechanistic studies are needed to investigate this hypothesis.

Serum Levels of Growth Factors in Alcohol-dependent Patients according to Comorbid Depressive Symptoms

OBJECTIVE

This study aims to reveal the relationship of depression with growth factors such as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and insulin-like growth factor-1 (IGF-1) in inpatients diagnosed with alcohol dependence, and to identify candidate growth factors as biological markers to indicate the comorbid of alcohol dependence and depression.

METHODS

This study examined demographic factors in 45 alcohol-dependent patients. The ADS (Korean version of the Alcohol Dependence Scale) and BDI (Korean version of Beck's Depression Inventory) were used. BDNF, NGF, and IGF-1 were measured through ELISA.

RESULTS

The average drinking quantity and the ADS score were significantly more severe in alcohol-dependent patients with depression than in those without depression. Linearly comparing BDNF, NGF, and IGF-1 with BDI values, IGF-1 was the growth factor significantly correlated with BDI scores. BDI scores were significantly correlated with ADS scores. IGF-1 was significantly higher in alcohol-dependent patients with depression. Alcohol-dependent patients with depression had greater alcohol use and more severe ADS scores. BDNF and NGF showed no significant difference between alcohol-dependent patients with and without depression, but IGF-1 was significantly higher in those with than in those without depression.

CONCLUSION

IGF-1 was found to be associated with depression in alcohol-dependent patients, suggesting that IGF-1 in alcohol- dependent patients could be an important biomarker to indicate whether alcohol-dependence is accompanied by depression.

Plasma concentrations of BDNF and IGF-1 in abstinent cocaine users with high prevalence of substance use disorders: relationship to psychiatric comorbidity

Recent studies have identified biomarkers related to the severity and pathogenesis of cocaine addiction and common comorbid psychiatric disorders. Monitoring these plasma mediators may improve the stratification of cocaine users seeking treatment. Because the neurotrophic factors are involved in neural plasticity, neurogenesis and neuronal survival, we have determined plasma concentrations of brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1) and IGF-1 binding protein 3 (IGFBP-3) in a cross-sectional study with abstinent cocaine users who sought outpatient treatment for cocaine (n = 100) and age/body mass matched controls (n = 85). Participants were assessed with the diagnostic interview 'Psychiatric Research Interview for Substance and Mental Disorders'. Plasma concentrations of these peptides were not different in cocaine users and controls. They were not associated with length of abstinence, duration of cocaine use or cocaine symptom severity. The pathological use of cocaine did not influence the association of IGF-1 with age observed in healthy subjects, but the correlation between IGF-1 and IGFBP-3 was not significantly detected. Correlation analyses were performed between these peptides and other molecules sensitive to addiction: BDNF concentrations were not associated with inflammatory mediators, lipid derivatives or IGF-1 in cocaine users, but correlated with chemokines (fractalkine/CX3CL1 and SDF-1/CXCL12) and N-acyl-ethanolamines (N-palmitoyl-, N-oleoyl-, N-arachidonoyl-, N-linoleoyl- and N-dihomo-γ-linolenoyl-ethanolamine) in controls; IGF-1 concentrations only showed association with IGFBP-3 concentrations in controls; and IGFBP-3 was only correlated with N-stearoyl-ethanolamine concentrations in cocaine users. Multiple substance use disorders and life-time comorbid psychopathologies were common in abstinent cocaine users. Interestingly, plasma BDNF concentrations were exclusively found to be decreased in users diagnosed with both primary and cocaine-induced disorders for mood and anxiety disorders. In summary, BDNF, IGF-1 and IGFBP-3 were not affected by a history of pathological use of cocaine supported by the absence of associations with other molecules sensitive to cocaine addiction. However, BDNF was affected by comorbid mood disorders. Further research is necessary to elucidate the role of BDNF and IGF-1 in the transition to cocaine addiction and associated psychiatric comorbidity.

Association between insulin and executive functioning in alcohol dependence: a pilot study

Alcohol dependence is a disorder ascribable to multiple factors and leads to cognitive impairment. Given that insulin dysregulation can cause cognitive impairment, patients with alcohol dependence are likely to develop insulin dysregulation such as that in diabetes. The purposes of this study are to identify an association between cognitive functioning and insulin and to investigate insulin as the biomarker of cognitive functioning in alcohol-dependent patients. Serum insulin levels were measured and cognitive functions were assessed in 45 patients with chronic alcoholism. The Korean version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD-K), a battery of cognitive function tests, was used to assess cognitive functioning. Serum insulin levels were not significantly correlated with most CERAD-K scores, but there was a significant negative correlation with scores on the Trail Making Test B, which is designed to measure executive functioning. Lower serum insulin levels were associated with slower executive functioning responses on the Trail Making Test B, suggesting that executive functioning may be in proportion to serum insulin levels. Thus, in patients with alcohol dependence, insulin level is associated with cognitive functioning. In addition, the present findings suggest that insulin level is a potential biomarker for determining cognitive functioning.

A human laboratory pilot study with baclofen in alcoholic individuals

Preclinical and clinical studies show that the GABA(B) receptor agonist baclofen may represent a pharmacotherapy for alcohol dependence (AD). However, the mechanisms by which baclofen affects drinking are not well characterized; thus this pilot study investigated possible baclofen's biobehavioral mechanisms. The design was a double-blind controlled randomized human laboratory pilot study. Fourteen non-treatment seeking alcohol-dependent heavy drinking subjects received either baclofen 10mg t.i.d. or an active placebo (cyproheptadine 2mg t.i.d., to control for sedation) for a 7-day period. At day 8, participants performed an alcohol cue-reactivity (CR) followed by an alcohol self-administration (ASA). Additionally, we explored possible moderators that might guide future larger studies, i.e. anxiety, family history and onset of alcoholism, and D4 dopamine receptor (DRD4) and 5-HTTLPR polymorphisms. The main results were a significant effect of baclofen for increasing stimulation (p=.001) and sedation (p<.01). Furthermore, when drinking during the ASA and the 2 days before was analyzed as a composite variable, there was a significant effect of baclofen to reduce alcohol consumption (p<.01). As for the exploratory analyses, baclofen's effects to increase alcohol sedation and to reduce alcohol consumption were limited to those individuals with DRD4 ≥7 repeats (DRD4L). Yet, baclofen's effects on alcohol consumption were also moderated by 5-HTTLPR LL genotype. In conclusion, baclofen's ability to reduce alcohol drinking may be related to its effects on the biphasic effects of alcohol, but larger studies are needed to confirm these preliminary findings.

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.

The loss of metabolic control on alcohol drinking in heavy drinking alcohol-dependent subjects

Background

Most physiological studies interested in alcohol-dependence examined ethanol as a pharmacological agent rather than a nutrient. We conducted two studies, which assessed the metabolic and endocrine factors involved in the regulation of alcohol and nutrient intake in alcohol-dependent (AD) subjects. We also examined the potential role of a disruption in energy balance in alcohol-dependence.

Methods and Results

In Study-1, quantitative dietetic interviews of eating and drinking habits were conducted with 97 AD subjects. The population was split around a median alcohol intake value of 12.5 kcal/kg/day. The results showed that the “low alcohol” drinking AD subjects had high Body Mass Index (BMI) and Fat Mass (FM) and alcohol intake was compensated for by a decrease in non-alcoholic intakes. “High alcohol” drinking AD subjects, on the other hand, had low BMI and FM and the total caloric intakes were largely above norms. In Study-2, 24 AD inpatients were submitted to dietetic interviews, calorimetry and blood samplings for the measurement of biomarkers of the regulation of metabolism and satiety, on day 2, 5 and 16 of abstinence. These patients were compared with 20 controls matched for age and gender. We observed in AD patients an increase in cortisol, leptin and PYY plasma levels and a decrease in ghrelin, which might explain the observed decrease in non-alcoholic intakes. However, alcoholic and non-alcoholic intakes correlated positively with basal metabolism and negatively with leptin and leptin/BMI.

Conclusion

For individuals consuming below12.5 kcal/kg/day of alcohol, alcohol intake is compensated for by a decrease in non-alcoholic nutrient intakes, probably due to changes in metabolic and satiety factors. For individuals consuming above 12.5 kcal/kg/day of alcohol, alcohol accelerates metabolism and decreases fat mass and leptin levels, and the total caloric intake largely exceeds norms. A dual model for regulation of energy intake in AD subjects is proposed.

From disordered eating to addiction: the "food drug" in bulimia nervosa

The high prevalence of substance abuse in individuals with bulimia nervosa (BN) and the pervasive symptom substitution in many types of drug addiction suggest that a number of substances--including food--can impair an individual's self-control, even in the presence of negative consequences. Nonetheless, the neurobiological similarities between BN and drug addiction are not clearly established. This review explores how the specific eating patterns seen in BN (binge eating and purging, with intermittent dietary restriction) are particularly addictive and differentiate BN from other eating disorders and obesity. A number of peripheral and central biological aberrations seen in BN may result in altered reward sensitivity in these individuals, particularly through effects on the dopaminergic system. Neurobiological findings support the notion that BN is an addictive disorder, which has treatment implications for therapy and pharmacological manipulations.

Baclofen promotes alcohol abstinence in alcohol dependent cirrhotic patients with hepatitis C virus (HCV) infection

Hepatitis C virus (HCV) and alcoholic liver disease (ALD), either alone or in combination, count for more than two thirds of all liver diseases in the Western world. There is no safe level of drinking in HCV-infected patients and the most effective goal for these patients is total abstinence. Baclofen, a GABA(B) receptor agonist, represents a promising pharmacotherapy for alcohol dependence (AD). Previously, we performed a randomized clinical trial (RCT), which demonstrated the safety and efficacy of baclofen in patients affected by AD and cirrhosis. The goal of this post-hoc analysis was to explore baclofen's effect in a subgroup of alcohol-dependent HCV-infected cirrhotic patients. Any patient with HCV infection was selected for this analysis. Among the 84 subjects randomized in the main trial, 24 alcohol-dependent cirrhotic patients had a HCV infection; 12 received baclofen 10mg t.i.d. and 12 received placebo for 12-weeks. With respect to the placebo group (3/12, 25.0%), a significantly higher number of patients who achieved and maintained total alcohol abstinence was found in the baclofen group (10/12, 83.3%; p=0.0123). Furthermore, in the baclofen group, compared to placebo, there was a significantly higher increase in albumin values from baseline (p=0.0132) and a trend toward a significant reduction in INR levels from baseline (p=0.0716). In conclusion, baclofen was safe and significantly more effective than placebo in promoting alcohol abstinence, and improving some Liver Function Tests (LFTs) (i.e. albumin, INR) in alcohol-dependent HCV-infected cirrhotic patients. Baclofen may represent a clinically relevant alcohol pharmacotherapy for these patients.

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.

Novel therapeutic strategies for alcohol and drug addiction: focus on GABA, ion channels and transcranial magnetic stimulation

Drug addiction represents a major social problem where addicts and alcoholics continue to seek and take drugs despite adverse social, personal, emotional, and legal consequences. A number of pharmacological compounds have been tested in human addicts with the goal of reducing the level or frequency of intake, but these pharmacotherapies have often been of only moderate efficacy or act in a sub-population of humans. Thus, there is a tremendous need for new therapeutic interventions to treat addiction. Here, we review recent interesting studies focusing on gamma-aminobutyric acid receptors, voltage-gated ion channels, and transcranial magnetic stimulation. Some of these treatments show considerable promise to reduce addictive behaviors, or the early clinical studies or pre-clinical rationale suggest that a promising avenue could be developed. Thus, it is likely that within a decade or so, we could have important new and effective treatments to achieve the goal of reducing the burden of human addiction and alcoholism.

Molecular targets of alcohol action: Translational research for pharmacotherapy development and screening

Alcohol abuse and dependence are multifaceted disorders with neurobiological, psychological, and environmental components. Research on other complex neuropsychiatric diseases suggests that genetically influenced intermediate characteristics affect the risk for heavy alcohol consumption and its consequences. Diverse therapeutic interventions can be developed through identification of reliable biomarkers for this disorder and new pharmacological targets for its treatment. Advances in the fields of genomics and proteomics offer a number of possible targets for the development of new therapeutic approaches. This brain-focused review highlights studies identifying neurobiological systems associated with these targets and possible pharmacotherapies, summarizing evidence from clinically relevant animal and human studies, as well as sketching improvements and challenges facing the fields of proteomics and genomics. Concluding thoughts on using results from these profiling technologies for medication development are also presented.

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.

Emerging drugs to treat alcoholism

IMPORTANCE OF THE FIELD

Alcoholism is a widespread disorder with substantial mortality and negative treatment outcomes. To date, few medications have been found to reduce relapse rates or drinking in alcohol-dependent patients.

AREAS COVERED IN THIS REVIEW

This review focuses on drugs that have been clinically tested for the treatment of alcohol dependence in clinical trials, pilot trials or which are considered to have a clinical perspective. For this purpose, a detailed Medline search was conducted on this issue. Although the neurochemical basis of alcoholism and the neuronal circuitry mediating its psychotropic effects have been explored in great detail in recent years, few drugs have emerged for the treatment of alcohol dependence, also because pharmaceutical companies have only a limited interest in this area of research. Acamprosate and the opioid antagonist naltrexone have been found to be effective, although data are mixed. A depot formula of naltrexone and the alternate opioid antagonist nalmefene have been studied in clinical trials and will presumably be introduced in the markets soon. Other emerging drugs are topiramate, novel acetaldehyde dehydrogenase (ALDH) inhibitors, baclofen, a combination therapy of gababentin and flumazenil and drugs targeting the cortitropin-releasing factor/neuropeptide Y mediated stress axis.

WHAT THE READER WILL GAIN

Insights on the neurochemical basis of alcohol dependence and possible targets of medications.

TAKE HOME MESSAGE

Acamprosate, naltrexone and the ALDH inhibitor disulfiram are proven medications for the treatment of alcohol dependence with modest efficacy. Novel alternate medications, a depot formulation of the opioid antagonist naltrexone and another oral opioid antagonist, nalmefene, are available now with good evidence for clinical efficacy. Novel ALDH inhibitors, antiepileptic drugs such as topiramate and drugs targeting the stress axis are currently among the most promising emerging drugs.

Sleep disturbance as a universal risk factor for relapse in addictions to psychoactive substances

Relapse to uncontrolled use of a psychoactive substance is arguably the single most defining characteristic of an addiction. Relapse following addiction treatment is very common with serious consequences to individuals, families, and the public system of care, making predictors of relapse a highly significant area of study. Before the turn of the century, most of the addiction treatment outcome literature focused on psychosocial predictors of relapse. More recently, investigating biological predictors of relapse specifically and treatment outcome broadly has gained momentum. This line of research has linked sleep disturbances to the risk of relapse among persons who are recovering from an alcohol addiction. Given common neurobiological and psychosocial processes in sleep and addictive behaviors, we hypothesize that the link between sleep disturbance and relapse risk observed among alcohol addiction generalizes to all other types of psychoactive substances. This hypothesis has the potential for helping develop more effective and targeted treatment approaches for persons with addiction. As initial support for the hypothesis, this paper reviews evidence on common neurobiological processes among various types of psychoactive substances that suggests sleep is a universal risk factor for relapse. A conceptual framework is also presented to articulate causal mechanisms. The paper concludes with implications for research and practice.

Role of the GABA(B) receptor system in alcoholism and stress: focus on clinical studies and treatment perspectives

Alcoholism and stress share some common neurobiological circuits, including the GABAergic system. In particular, the GABA(B) receptor seems to play an important role. The GABA(B) receptor agonist baclofen has been studied as a treatment for alcohol-dependent subjects. Baclofen administration in alcohol-dependent patients was able to promote abstinence, inducing the remission of withdrawal symptoms, reducing alcohol craving, and reducing alcohol intake. Baclofen also reduced anxiety in alcohol-dependent subjects, probably acting on brain stress circuitry and/or on other neuroendocrine systems. Baclofen also showed excellent safety and tolerability, even in alcohol-dependent patients with advanced liver disease (i.e., cirrhosis). Future studies should investigate which alcoholic subtype may better benefit of the administration of baclofen in the treatment of alcohol dependence.

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.

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.

Is cortisol involved in the alcohol-related fat mass impairment? A longitudinal clinical study

AIMS

Subjects with chronic alcohol abuse can present several metabolic and nutritional alterations. The hypothalamic-pituitary-adrenal (HPA) axis may play a role in these nutritional and metabolic disorders. The goal of this study was to investigate if there is any relationship between HP-hormones and metabolic and nutritional parameters in alcoholic subjects.

METHODS

Sixteen alcoholics were considered before and after 3 months of total alcohol abstinence. HP-related hormones were determined. Nutritional and metabolic parameters were assessed by dual-energy X-ray absorptiometry (DXA) and indirect calorimetry.

RESULTS

At baseline, a significant negative correlation was found between fat mass (FM) and cortisol (r = -0.54, P = 0.03). During abstinence, a significant increase of both body mass index (BMI) (P < 0.0001) and FM (P < 0.0001) was found at 12 weeks compared to baseline. A significant decrease of both plasma cortisol (P = 0.044) and aldosterone (P = 0.023) was found at 12 weeks compared to baseline. At 12 weeks, the significant correlation between cortisol and FM disappeared.

CONCLUSIONS

A higher HPA-axis activation-reflected by higher cortisol levels-was associated with a lower FM in alcoholics. Conversely, during total abstinence a reduced HPA-axis activity can play a role in the parallel nutritional recovery. The present results suggest a role of the HPA axis throughout cortisol both in the etiology of the alcohol-related nutritional alterations and in their recovery after a period of total alcohol abstinence.

Increased levels of adiponectin and resistin in alcohol dependence--possible link to craving

Recent studies suggested a role of appetite regulating peptides like leptin and ghrelin in alcohol dependence and particularly in the neurobiology of alcohol craving. Aim of the present study was to investigate alterations of the adipocytokines adiponectin and resistin in alcohol-dependent patients. We analyzed a sample of 88 patients at admission for alcohol detoxification and after 1 week of withdrawal treatment in comparison to 89 healthy controls. Adiponectin and resistin serum levels were measured using commercial ELISA kits. The extent of alcohol craving was obtained using the Obsessive Compulsive Drinking Scale (OCDS). Adiponectin and resistin serum levels were significantly elevated in patients with alcohol dependence at both dates (admission and after 1 week of treatment) compared to healthy controls. Adiponectin decreased significantly during the course of withdrawal (T=3.44, p=0.001) while resistin serum levels showed a slight increase (T=-1.83, p=0.071). In a multivariate approach the extent of alcohol craving was significantly associated with adiponectin but not with resistin serum levels in male patients (Beta=-0.255, p=0.025). Results for female patients were not significant. Our findings provide first evidence for an alteration of the adipocytokines adiponectin and resistin during alcohol withdrawal. Furthermore, adiponectin may be involved in the neurobiology of alcohol craving, possibly via its effects on the hypothalamic circuits.

NGF plasma levels increase due to alcohol intoxication and decrease during withdrawal

Recent studies show that alcohol dependence is associated with alterations in plasma levels of nerve growth factor (NGF). The aim of this study was to further elucidate reported alterations in NGF plasma levels during alcohol intoxication and withdrawal. Therefore, we assessed NGF plasma levels by enzyme-linked immunosorbent assay (ELISA) on admission (day 0) and day 7 of alcohol withdrawal in male alcohol dependent patients (n=75) in comparison to healthy controls (n=44). We found significant higher (U=1005.0, p<0.001) NGF plasma levels in the alcohol-dependent patients. Subgroup analysis showed significant higher (U=-2.934, p=0.003) NGF plasma levels in patients suffering from acute alcohol intoxication (group A) than in early abstinent patients (group B). From day 0 to day 7 of alcohol withdrawal NGF plasma levels decreased significantly in both groups (group A: Z=-3.118, p=0.002, group B: Z=-2.103, p=0.035). Our results suggest that acute alcohol intoxication is associated with an increase in NGF plasma levels, which decrease during alcohol withdrawal. These results suggest that NGF plasma levels increase as part of a regulation mechanism that counteracts alcohol intoxication.

Renin and aldosterone but not the natriuretic peptide correlate with obsessive craving in medium-term abstinent alcohol-dependent patients: a longitudinal study

Both animal and human studies suggest that volume-regulating hormones could play a role in alcohol dependence as well as in alcohol craving. The role of the volume-regulating hormones, renin, aldosterone, and the N-terminal pro B-type natriuretic peptide (NT-proBNP) in alcohol craving was therefore evaluated in the present study. Twenty-five actively drinking alcohol-dependent patients satisfied the inclusion criteria and were enrolled into the study. The volume-regulating hormones, renin, aldosterone, and the NT-proBNP, and craving measurements--Obsessive-Compulsive Drinking Scale (OCDS) and Penn Alcohol Craving Scale (PACS)--were performed at baseline and after 12 weeks. Sixteen patients remained totally abstinent for the entire 12 weeks and were available for the second assessments. At baseline, no correlations between hormones and craving scores were found with either the 25 patients initially enrolled or the 16 abstinent patients. At 12 weeks, a significant increase of renin and a significant decrease of aldosterone were observed. Aldosterone showed a significant direct correlation with the obsessive OCDS subscore (r=0.59, P=.016) and a trend toward a significant direct correlation with the PACS score (r=0.48, P=.057). Renin demonstrated a significant direct correlation with the obsessive OCDS subscore (r=0.51, P=.041) and with the PACS score (r=0.56, P=.025). The NT-proBNP never correlated with craving measurements. In conclusion, the renin-aldosterone axis could play a role in craving in medium-term abstinent patients and thereby leading to the hypothesis that alcohol craving could be influenced by the fluid volume intake.

Alcohol dependence is associated with reduced plasma and fundic ghrelin levels

BACKGROUND

Conflicting data concerning the involvement of ghrelin in the pathophysiology of alcohol dependence have been reported. The aim of this study is to investigate how chronic alcohol ingestion influences plasma ghrelin levels and whether potential changes observed in plasma relate to modifications in ghrelin production in the stomach where this peptide is primarily synthesized.

MATERIALS AND METHODS

Fifty-one consecutive alcoholics admitted for alcohol withdrawal were prospectively enrolled and compared to a control group of 32 healthy volunteers matched for age, sex, height and weight. All subjects underwent fasting plasma ghrelin determination. Twenty-seven randomly selected alcoholics and 17 controls underwent gastroscopy for fundic and duodenal biopsies. Tissues were fixed for histology or frozen in liquid nitrogen for ghrelin protein and mRNA determinations by a radioimmunoassay and quantitative polymerase chain reaction, respectively. Alcohol consumption was normalized to body weight (BW) or body mass index (BMI) given the influence of BW and volume distribution on alcohol levels.

RESULTS

Plasma and fundic ghrelin protein levels were significantly decreased in alcoholics. Fundic but not plasma ghrelin protein levels inversely correlated with alcohol consumption normalized to BW or BMI. Ghrelin mRNA levels in fundic biopsies were similar in alcoholics and controls. No significant differences in duodenal ghrelin protein and mRNA levels were found between both groups.

CONCLUSIONS

Alcoholism was associated with decreased plasma ghrelin levels partly due to reduced ghrelin production in the stomach. Alcohol affected ghrelin production on the post-transcriptional level in the fundus, whereas duodenal ghrelin secretion did not respond in a similar manner to alcohol intake.