Washington, Sept 24 : Ghrelin is known to have an effect on food intake by increasing feelings of hunger and the urge to eat. But now, a new study has shown that it may also be involved in addictive behaviours and brain reward.
Ghrelin is a peptide, mainly produced in the stomach, but also found in small amounts in the brain.
The study examined ghrelin's role in addictive behaviours and findings indicated that variations in the genes producing ghrelin and its receptor are more common in individuals considered heavy drinkers.
"Previous research had shown that ghrelin levels in blood plasma are altered in addictive behaviours such as alcohol dependence and compulsive overeating," said Jorgen Engel, professor of pharmacology at the Sahlgrenska Academy, University of Gothenburg. It may be that common mechanisms in the brain underlie different forms of addictive behaviours, including compulsive overeating, pathological gambling and drug dependence," he said.
"We hypothesized that the ghrelin system may be an important player in the brain-reward systems and, more specifically, wanted to investigate if the ghrelin system is involved in alcohol dependence in humans," he added.
For the study, the researchers recruited 417 Spanish individuals from the general population as well as heavy drinkers admitted to a hospital for treatment.
The study sample - comprised of abstainers, moderate and heavy alcohol drinkers - was then examined for single nucleotide polymorphisms (SNPs) in the pro-ghrelin and growth hormone secretagogue receptors (GHS-R1A) gene.
The researchers found that SNP rs2232165 of the GHS-R1A gene was associated with heavy alcohol consumption.
SNP rs2948694 of the same gene as well as haplotypes of both the pro-ghrelin and the GHS-R1A genes were associated with an increased body mass in individuals consuming heavy amounts of alcohol.
"Not only are these specific variations in the genes producing ghrelin and its receptor more common in heavy alcohol-using individuals, these variations also seem to have an influence on the body weight of these heavy drinking individuals, as we found an association with an increased body weight in these patients," said Engel.
"In other words, if you are a carrier of these genetic variants in the ghrelin or ghrelin receptor gene, you are more susceptible to having multiple addictive behaviours such as alcohol dependence and overeating," he added.
The study will be published in the December issue of Alcoholism: Clinical and Experimental Research and is currently available at Early View.