A genetic variant of a receptor in the brains reward circuitry heightens the stimulating effects of early exposures to alcohol and increases alcohol consumption, according to a new study by researchers at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). Conducted in rhesus monkeys, the study extends previous research that suggests an important role for a similar brain receptor variant in the development of human alcohol use disorders. A report of the findings is published in the March, 2007 issue of the Archives of General Psychiatry.
"Although the pathway to alcoholism is influenced by many factors, our findings affirm that individuals who possess this receptor variant may experience enhanced pleasurable effects from alcohol that could increase their risk for developing alcohol abuse and dependence," notes Markus Heilig, M.D., Ph.D., NIAAA Clinical Director and the studys senior author.
Molecules known as opioid peptides bind to opioid receptors in the brain to signal experiences of reward and reinforcement, as well as the euphoria and other positive subjective effects produced by alcohol. Previous studies have shown that, among the brains various subtypes of opioid receptors, the mu-subtype is most likely responsible for transmitting alcohols positive effects.
"We also know that there are several genetic variants of the human mu-opioid receptor," notes first author Christina Barr, V.M.D., Ph.D., a lead investigator in NIAAAs Laboratory of Clinical and Translational Studies and Laboratory of Neurogenetics. "One of these, designated 118G, has a greatly enhanced ability to bind opioid peptides. People who have this variant of the receptor have reported increased euphoria following alcohol consumption."
Drs. Barr, Heilig, and their colleagues note that recent studies have linked the 118G mu-opioid receptor with alcohol dependence in humans. In the current s
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Contact: John Bowersox
jbowersox@niaaa.nih.gov
301-443-3860
NIH/National Institute on Alcohol Abuse and Alcoholism
6-Mar-2007