Previous research has implicated the brain's opioid system in the development of alcohol-use disorders. The mu-opioid receptor, which is encoded by the OPRM1 gene, is the primary site of action for opiates with high abuse potential, such as opium and heroin, and may also contribute to the effects of non-opioid drugs, such as cocaine and alcohol. Findings published in the December issue of Alcoholism: Clinical & Experimental Research indicate that individuals with the G variant of the A118 polymorphism of the OPRM1 gene have greater subjective feelings to alcohol's effects as well as a greater likelihood of a family history of alcohol-use disorders.
"Alcohol releases endogenous opiates which, in turn, seem to influence the mesolimbic dopamine system," said Kent E. Hutchison, associate professor of psychology at the University of Colorado at Boulder and lead author of the study. "This system is involved in craving and the motivation to use alcohol and drugs. Thus, it is alcohol's effects on endogenous opioids that act as the gateway through which alcohol may influence this system."
"It is well known that alcohol dependence tends to run in families," said Robert Swift, professor of psychiatry and human behavior at Brown University and Associate Chief of Staff for Research at the Providence VA Medical Center. "The inheritance of alcoholism is complex, but there are suggestions that the opiate systems in the brain are involved. Our brains contain proteins, called enkephalins and endorphins, that act like morphine and other opiates derived from the poppy plant. Several researchers