Background
Peroxisome proliferator-activated receptor (PPAR) agonists reduce voluntary ethanol consumption in rat models and are promising therapeutics in the treatment of drug addictions. We studied the effects of different classes of PPAR agonists on chronic ethanol intake and preference in mice with a genetic predisposition for high alcohol consumption and then examined human genome wide association data for polymorphisms in PPAR genes in alcohol-dependent subjects.
Methods
Two different behavioral tests were used to measure intake of 15% ethanol in C57BL/6J male mice: 24-hour two-bottle choice and limited access (3-hour) two-bottle choice, drinking in the dark. We measured the effects of pioglitazone (10 and 30 mg/kg), fenofibrate (50 and 150 mg/kg), GW0742 (10 mg/kg), tesaglitazar (1.5 mg/kg) and bezafibrate (25 and 75 mg/kg) on ethanol intake and preference. Fenofibric acid, the active metabolite of fenofibrate, was quantified in mouse plasma, liver, and brain by LC-MS/MS. Data from a human genome wide association study (GWAS) completed in the Collaborative Study on the Genetics of Alcoholism (COGA) was then used to analyze the association of single nucleotide polymorphisms (SNPs) in different PPAR genes (PPARA, PPARD, PPARG, and PPARGC1A) with two phenotypes: DSM-IV alcohol dependence (AD) and the DSM-IV criterion of withdrawal.
Results
Activation of two isoforms of PPARs, α and γ, reduced ethanol intake and preference in the two different consumption tests in mice. However, a selective PPARδ agonist or a pan agonist for all three PPAR isoforms did not decrease ethanol consumption. Fenofibric acid, the active metabolite of the PPARα agonist fenofibrate, was detected in liver, plasma, and brain after 1 or 8 days of oral treatment. The GWAS from COGA supported an association of SNPs in PPARA and PPARG with alcohol withdrawal and PPARGC1A with AD but found no association for PPARD with either phenotype.
Conclusions
We provide convergent evidence using both mouse and human data for specific PPARs in alcohol action. Reduced ethanol intake in mice and the genetic association between AD or withdrawal in humans highlight the potential for repurposing FDA-approved PPARα or PPARγ agonists for the treatment of AD.