A genetic variant of a receptor in the brain's reward circuitry plays an important role in determining whether the neurotransmitter dopamine is released in the brain following alcohol intake, according to a study led by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health. Dopamine is involved in transmitting the euphoria and other positive subjective effects produced by alcohol.
A report of the findings, which help explain the diverse genetic susceptibility for alcohol use disorders, will appear online in Molecular Psychiatry on May 18, 2010.
"By advancing our understanding of the neurobiology that underlies the addictive properties of alcohol, this finding helps us understand why alcohol affects people in very different ways," says NIAAA Acting Director Kenneth R. Warren, Ph.D. "This kind of information also aids the development of personalized medications for alcohol problems."
Receptors for brain molecules known as opioid peptides help initiate the neurochemical reactions that underlie the positive effects produced by alcohol. Activation of the mu-subtype of opioid receptor following alcohol consumption triggers the release of dopamine from the forebrain.
"But there is much variation in alcohol-induced responses that are thought to be related to dopamine," explains Markus Heilig, M.D., Ph.D., NIAAA clinical director and the study's senior author. "Previous studies by our group and others suggest that variants of opioid genes may contribute to the observed variation, possibly through effects on alcohol-induced dopamine release."
He notes, for example, that people who carry the mu-opioid receptor variant designated as 118G report increased euphoria following alcohol consumption. Dr. Heilig's group has reported that a similar mu-opioid receptor variant in monkeys heightened the stimulating effects of alcohol and increased their alcohol c
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NIH/National Institute on Alcohol Abuse and Alcoholism