Pharmacogenetics of Alcohol: Treatment Implications

Condition(s) targeted: Alcohol Related Disorders; Alcoholism; Alcohol Abuse

Intervention: Dutasteride (Drug); Alcohol beverage (Drug); Placebo pill (Drug); Placebo alcohol beverage (Drug); Skin Biopsy (Procedure)

Phase: N/A

Status: Recruiting

Sponsored by: University of Connecticut Health Center

Official(s) and/or principal investigator(s):
Jonathan Covault, MD, PhD, Principal Investigator, Affiliation: University of Connecticut Health Center

Overall contact:
Jessica M Cohen, MS, Phone: 860-679-4186, Email: jcohen@uchc.edu

This study will explore the hypothesis that effects of alcohol are in part mediated by increased production of neuroactive steroids, which interact with GABAA-receptors. We propose to study non-dependent drinkers using a 4-session within-subjects design in which alcohol / placebo is paired with dutasteride / placebo pretreatment. Dutasteride is a 5-alpha steroid reductase (5AR) inhibitor that limits the production of dihydrotestosterone and the 5a-reduced neuroactive steroids allopregnanolone, pregnanolone and 3a,5a-THDOC. This work continues our pilot studies in this area in which we demonstrated that both an alcohol-dependence associated GABRA2 allele and inhibition of 5AR reduce the subjective response to alcohol. We will extend work in this area by 1) examining a larger group of subjects that includes both light and heavy drinkers balanced on GABRG1-GABRA2 genotype, 2) include objective measures of alcohol's effects, 3) measure plasma concentrations of neuroactive steroids and their adrenal steroid hormone precursors at several time points following alcohol administration, 4) examine effects of a more potent and specific inhibitor of 5a-reductase (to validate and clarify the relationship of neuroactive steroids to alcohol effects), and 5) examine the effects of natural variation in other genes, particularly those encoding in steroid 5a-reductase, m-opioid receptor, GABA and glutamate receptor subunits, serotoninergic genes and those involved in the biology of stress responses, on the between subject differences in acute alcohol effects. Aim 1. Examine the effect of GABRG1-GABRA2 genotype on multiple responses to alcohol in 80 healthy human subjects. Aim 2. Examine the effects of dutasteride pre-treatment on alcohol-induced increases in circulating neuroactive steroid levels and on the subjective, motor and cognitive effects of acute alcohol consumption. In addition, we will examine the interactive effects of GABRG1-GABRA2 genotype and dutasteride on the response to alcohol. Aim 3. Examine the impact of genetic variation in the 5a-reductase and m-opioid receptor genes on alcohol-induced neuroactive steroid signaling as well as the effect of natural variation in GABA and glutamate receptor subunits, serotoninergic genes and those involved in the biology of stress responses, on the between subject differences in acute alcohol effects. Aim 4. Conduct an optional sub-study to examine alcohol induced changes in neuroactive steroid metabolism in vitro using neural cultures generated from skin biopsies obtained from study participants. This aim is an in vitro sub-study that will allow comparison of subjective and behavioral effects of alcohol measured in Aims 1-3 of the main study with and alcohol induced changes in neuroactive steroid metabolism directly in neural cells derived in vitro from induced pluripotent stem cells generated from skin biopsies obtained for Aim 4 from study participants.

Official title: Subjective and Physiological Effects of Alcohol: Role of Genetic Variation and Adrenal Hormones

Study design: Other, Randomized, Double Blind (Subject, Caregiver), Crossover Assignment, Pharmacodynamics Study

Primary outcome: Subjective measure of alcohol effects, static ataxia, working memory and neuroactive steroid levels as a function of alcohol vs. placebo and dutasteride vs. placebo and stratified by GABRG1-GABRA2 genotype.

Detailed description: Alcohol has multiple pharmacological effects, though which of these effects relate to the risk of alcohol dependence is not clear. Family-based and case-control genetic studies of alcohol dependence indicate that genetic variations of the adjacent GABAA g1- and a2-subunit genes, GABRG1 and GABRA2, influence the risk of developing alcohol dependence. Preliminary results from our alcohol laboratory studies in humans suggest that variation in GABRA2 influences the subjective effects of alcohol. Animal studies indicate that the neuroactive steroid allopregnanolone is an alcohol-modulated endogenous agonist at GABAA receptors and that genetic variation in steroid 5a-reductase type I gene which generates neuroactive steroids, may moderate alcohol effects. Studies in humans have identified a functional m-opioid receptor polymorphism (Asn40Asp) that moderates the feedback regulation of the HPA axis and may be associated with variation in the neurosteroid response to acute alcohol. To better define the role of GABRA2 gene variation, neuroactive steroids and genetic variants of 5a-reductase and m-opioid receptor genes on the acute effects of alcohol in humans, we propose to conduct a laboratory study of non-alcohol dependent drinkers using a 4-session design in which alcohol/placebo beverage is paired with dutasteride/placebo pretreatment. Dutasteride, an inhibitor of both type I and type II 5a-reductase enzymes, blocks the production of 5a-reduced neuroactive steroids. This study will extend our preliminary findings with finasteride by including a) a placebo control for alcohol, b) a more specific inhibitor of both 5a-reductase isoenzymes, c) a larger group of subjects (including both light and heavy drinkers), d) quantitative tests of static ataxia and response inhibition, e) plasma concentrations of neuroactive steroids and their adrenal steroid hormone precursors at several time points following alcohol administration, and f) the effects of polymorphisms in steroid 5a-reductase enzymes and m-opioid receptor genes on acute alcohol effects (including changes in levels of neuroactive steroids).

Correlation of in vitro effects of alcohol on neural tissue for defined biological process with subjective and behavioral effects of alcohol in human subjects offers the potential to better understand natural variation between subjects in alcohol effects and risk of alcohol use disorders. Recent descriptions of methods to reprogram human post-natal and adult somatic cells into pluripotent stem cells (induced pluripotent stem cells or iPS cells) in vitro (Takahashi, Tanabe et al. 2007; Lowry, Richter et al. 2008; Nakagawa, Koyanagi et al. 2008; Park, Zhao et al. 2008) may now allow examination of correlations between subject variation in alcohol response and the direct effects of alcohol on neural tissue in vitro. In this sub-study we propose to demonstrate use of this technology by conducting a parallel examination of between subject differences in a) alcohol effects and their modulation by a pharmacologic probe of neuroactive steroid production in human volunteers (main study aims 1-3), and b) alcohol induced changes in neuroactive steroid metabolism in vitro using neural cultures generated from these same subjects (this sub-study). Aim 1. Generate frozen stocks of adult primary fibroblast cultures from study participants enrolled in our ongoing dutasteride/alcohol human laboratory study. Aim 2. Generate induced pluripotent stem (iPS) cell lines from each of 8-10 participants (3-5 heavy drinkers and 3-5 light drinkers) with at least one from each group who show either robust or minimal effect of dutasteride pretreatment on acute alcohol subjective effects. Aim 3. Examine the effect of short term exposure of neural cells generated by differentiation of subject specific iPS cells, to 25, 50 or 100 mM (0. 115 to 0. 460 %) ethanol on the production of the neuroactive steroid allopregnanolone and of type I and II 5a-reductase protein and mRNA produced by these cells.

140 subjects will be recruited for the main study and 70 subjects in the substudy will be subjects who have, or are participating, in the above main study.

Minimum age: 21 Years. Maximum age: 45 Years. Gender(s): Male.

Criteria:

Inclusion Criteria:

- Main Study: Subjects will be healthy volunteers with or without parental history of

alcoholism who are 21-45 years old and who have a BMI >18. 5 and <32. 5. Drinking history: All subjects must report at least one occasion in the prior month of drinking at least 3 drinks on a single day; additionally, LD subjects will be selected if they drink 1-3 drinks, 1-3 times per week (up to 5 drinks per week on average), with no more than one occasion in the past 2 months on which they drank >4 drinks. HD subjects will be selected if they report drinking at least 10 drinks per week, with at least one episode per week of heavy drinking.

- Sub study: Subjects must be currently enrolled in or have completed the

dutasteride/alcohol main study covered by this IRB protocol. For subjects who have completed the main study, they will be contacted only if they had previously given permission to be contacted about participation in additional studies.

Exclusion Criteria:

- Main Study: Subjects cannot have a current or past DSM-IV diagnosis of alcohol or

drug dependence, current or past 24-months diagnosis of alcohol or drug abuse or another major psychiatric disorder, neurological illness, have had a hypersensitivity reaction to dutasteride, evidence of liver dysfunction, currently be using benzodiazepines, other psychotropic medications or medications that are known to influence steroid hormone levels or metabolism or modify the effects of alcohol. Nicotine-dependent subjects will be excluded to avoid the confounding effects of nicotine withdrawal during day-long laboratory sessions. Women are not allowed to participate. Subjects anticipating moving from the area during the period of their planned study participation will be excluded from study entry.

- Sub Study: Subjects cannot have a current or past DSM-IV diagnosis of alcohol or drug

dependence, current or past 24-months diagnosis of alcohol or drug abuse or another major psychiatric disorder, neurological illness, have had a hypersensitivity reaction to dutasteride, evidence of liver dysfunction, currently be using benzodiazepines, other psychotropic medications or medications that are known to influence steroid hormone levels or metabolism or modify the effects of alcohol.

Jessica M Cohen, MS, Phone: 860-679-4186, Email: jcohen@uchc.edu

University of Connecticut Health Center, Farmington, Connecticut 06030, United States; Recruiting
Jessica M Cohen, MS, Phone: 860-679-4186, Email: jcohen@uchc.edu
Timothy Pond, BS, Phone: 860-679-8757, Email: tpond@uchc.edu
Albert J Arias, MD, Sub-Investigator
Lance O Bauer, PhD, Sub-Investigator
Henry R Kranzler, MD, Sub-Investigator
Cheryl Oncken, MD, Sub-Investigator
Carolyn Drazinic, MD, PhD, Sub-Investigator
Richard Feinn, PhD, Sub-Investigator
Peter Snyder, PhD, Sub-Investigator

Starting date: March 2007
Ending date: May 2011
Last updated: September 8, 2009