Washington: A new animal study has found that long-term relationships make the commonly abused drug amphetamine less appealing.
The findings suggested that social bonds formed during adulthood lead to changes in the brain that may protect against drug abuse.
The researchers directed by Zuoxin Wang of Florida State University carried out their study in prairie voles- rodents that form lifelong bonds with mating partners.
They found that male voles in established relationships displayed less interest in amphetamine compared with their single counterparts.
Amphetamine exposure led to changes in the nucleus accumbens — a part of the brain``s reward system — that differed depending on the relationship status of the voles.
Wang and his colleagues found brain cells of both paired and single voles released a similar amount of dopamine — a brain chemical important in pleasurable activities like eating and sex — in response to amphetamine.
However, this released dopamine may have had differential effects in paired and single voles.
Once released, dopamine binds to molecules called receptors on the surface of brain cells. Amphetamine use increased D1 receptor binding in the nucleus accumbens in single voles, but decreased it in paired voles, suggesting the single and paired voles had opposite responses to the drug.
Drugs that blocked dopamine from binding to the D1 receptor in the nucleus accumbens lessened amphetamine reward in single voles, while drugs that increased dopamine binding at this site appeared to make amphetamine more appealing to the paired voles.
"Our results indicate that the pair bonding experience may alter the neurobiological response to drugs of abuse, which in turn may diminish the rewarding effects of the drug itself," said Wang study author.
The study was published in the June 1 issue of The Journal of Neuroscience.