Study in rats finds that even one injection leads to dependent behavior
THURSDAY, May 28 (HealthDay News) -- A naturally occurring protein plays a role in the disrupted functioning of the brain's reward circuitry seen in people with drug and alcohol dependence, says a new study.
"If we can understand how the brain's circuitry changes in association with drug abuse, it could potentially suggest ways to medically counteract the effects of dependency," Scott Steffensen, a study co-author and a neuroscientist at Brigham Young University in Provo, Utah, said in a news release.
Previous studies found that chronic drug users can experience an increase of a protein known as brain-derived neurotrophic factor (BDNF) in the brain's reward circuitry. In the new study, the researchers found that a single injection of BDNF made rats behave as if they were dependent on opiates, even though they'd never been given the drugs.
The BDNF injections caused the rats to leave their usual area -- with its comforting smells, lighting and texture -- in search of a fix. The researchers also found that the BDNF injections in the rats caused certain chemicals that normally inhibit neurons in the brain's reward circuitry to excite neurons, which is what happens when people become dependent on drugs.
The finding suggests that BDNF plays a major role in inducing drug dependency, one important aspect of drug addiction, Steffensen said.
The study is published in the May 29 issue of the journal Science.
The U.S. National Institute on Drug Abuse has more about drug abuse and addiction.
-- Robert Preidt
SOURCE: Brigham Young University, news release, May 28, 2009
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