Ghrelin receptor (GHS-R1A) antagonism suppresses both alcohol consumption and the alcohol deprivation effect in rats following long-term voluntary alcohol consumption

PLoS One. 2013 Aug 20;8(8):e71284. doi: 10.1371/journal.pone.0071284. eCollection 2013.

Abstract

Alcohol dependence is a heterogeneous disorder where several signalling systems play important roles. Recent studies implicate that the gut-brain hormone ghrelin, an orexigenic peptide, is a potential mediator of alcohol related behaviours. Ghrelin increases whereas a ghrelin receptor (GHS-R1A) antagonist decreases alcohol consumption as well as operant self-administration of alcohol in rodents that have consumed alcohol for twelve weeks. In the present study we aimed at investigating the effect of acute and repeated treatment with the GHS-R1A antagonist JMV2959 on alcohol intake in a group of rats following voluntarily alcohol consumption for two, five and eight months. After approximately ten months of voluntary alcohol consumption the expression of the GHS-R1A gene (Ghsr) as well as the degree of methylation of a CpG island found in Ghsr was examined in reward related brain areas. In a separate group of rats, we examined the effect of the JMV2959 on alcohol relapse using the alcohol deprivation paradigm. Acute JMV2959 treatment was found to decrease alcohol intake and the effect was more pronounced after five, compared to two months of alcohol exposure. In addition, repeated JMV2959 treatment decreased alcohol intake without inducing tolerance or rebound increase in alcohol intake after the treatment. The GHS-R1A antagonist prevented the alcohol deprivation effect in rats. There was a significant down-regulation of the Ghsr expression in the ventral tegmental area (VTA) in high- compared to low-alcohol consuming rats after approximately ten months of voluntary alcohol consumption. Further analysis revealed a negative correlation between Ghsr expression in the VTA and alcohol intake. No differences in methylation degree were found between high- compared to low-alcohol consuming rats. These findings support previous studies showing that the ghrelin signalling system may constitute a potential target for development of novel treatment strategies for alcohol dependence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Alcohol Drinking / drug therapy*
  • Alcohol Drinking / metabolism
  • Alcohol Drinking / physiopathology
  • Alcoholism / drug therapy*
  • Alcoholism / metabolism
  • Alcoholism / physiopathology
  • Animals
  • CpG Islands
  • DNA Methylation / drug effects
  • Gene Expression Regulation
  • Ghrelin / genetics
  • Ghrelin / metabolism*
  • Glycine / analogs & derivatives*
  • Glycine / pharmacology
  • Male
  • Rats
  • Rats, Wistar
  • Receptors, Ghrelin / antagonists & inhibitors*
  • Receptors, Ghrelin / genetics
  • Receptors, Ghrelin / metabolism
  • Self Administration
  • Signal Transduction
  • Substance Withdrawal Syndrome / prevention & control*
  • Triazoles / pharmacology*
  • Ventral Tegmental Area / drug effects*

Substances

  • Ghrelin
  • N-(1-(4-(4-methoxybenzyl)-5-phenethyl-4H-1,2,4-triazol-3-yl)-2-(1H-indol-3-yl)ethyl)-2-aminoacetamide
  • Receptors, Ghrelin
  • Triazoles
  • Glycine

Grants and funding

The research was supported by grants from the Swedish Research Council (grant no. K2006-21X-04247-33-3, 2009-2782 and K2010-80X-21496-01-6), The Swedish Brain Foundation, LUA/ALF (grant no. 148251) from the Sahlgrenska University Hospital, Alcohol Research Council of the Swedish Alcohol Retailing Monopoly and the foundations of Adlerbertska, Fredrik and Ingrid Thuring, Tore Nilsson, Längmanska, Torsten and Ragnar Söderberg, Wilhelm and Martina Lundgren, NovoNordisk, Knut and Alice Wallenberg, Magnus Bergvall, Anérs, Jeansons, ÅkeWiberg, the Swedish Society of Medicine, Swedish Society for Medical Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.