The gene, Mpdz, is involved in physical dependence on a class of drugs known as sedative-hypnotics, which are widely used for their euphoric and sedative effects. Drugs in this class include alcohol, inhalants, barbiturates, benzodiazepines, like Rohypnol or "roofies," and some other "club drugs."

Scientists in the Portland Alcohol Research Center (PARC) and the Department of Behavioral Neuroscience, OHSU School of Medicine, found Mpdz using mice bred to possess a region of a chromosome known to be associated with a predisposition to physical dependence and withdrawal from sedative-hypnotics like alcohol and barbiturates. During the four-year search, the scientists narrowed the initial field of more than 1,000 candidate genes to only five genes, and finally to one.

"We know that a host of biological and environmental factors interact in a complex manner throughout the addictive process to influence drug use or abuse. We think that physical dependence on sedative-hypnotic drugs and associated withdrawal episodes constitutes a motivational force that perpetuates drug use or abuse and contributes to relapse," said Nikki Walter, research associate in behavioral neuroscience and a study co-author.

"Now that we have identified one of the key genes, we can begin to study how this gene regulates brain circuits involved in drug dependence and withdrawal," said Kari Buck, Ph.D., associate professor of behavioral neuroscience and senior author of the study, which appears in the current issue of the journal Nature Neuroscience.

The discovery also is more evidence that drug and alcohol dependency is genetically determined. Previous OHSU studies have shown that genetics greatly influence alcohol and drug addiction and withdrawal.

"There are a lot of reasons why people drink
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Contact: Jonathan Modie
modiej@ohsu.edu
503-494-8231
Oregon Health & Science University
8-Jul-2004