Subordinate monkeys placed under stress more likely to choose cocaine over food
SUNDAY, April 6 (HealthDay News) -- Monkeys with lower social standing are more likely than dominant monkeys to choose cocaine over food when faced with a stressful situation, a new study finds.
The Wake Forest University School of Medicine researchers exposed four dominant and four subordinate male cynomolgus monkeys to a socially stressful situation. Each monkey was taken out of its home cage and placed in an unfamiliar cage surrounded by four unfamiliar animals. While the monkeys were physically safe, they could hear and see the aggressive behavior of the other monkeys.
PET scans of the monkeys' brains showed that the subordinate monkeys had pronounced decreased activity in areas of the brain involved with stress and anxiety (amygdala and hippocampus) and in emotional and social processing (anterior cingulate cortex). The dominant monkey showed increases in reward-related areas of the brain.
After being in an unfamiliar cage, the monkeys were given the opportunity to select between a lever that they knew delivered cocaine or one that delivered food. The subordinate monkeys were more likely than dominate monkeys to choose cocaine over food.
The study was to be presented Sunday at Experimental Biology 2008 in San Diego.
The findings may offer clues to the social context of drug use and addiction in humans, the researchers said.
"We believe this type of research can be used to identify better treatment strategies, including providing environmental enrichment, that may affect the likelihood of using drugs," Michael A. Nader, professor of physiology and pharmacology at Wake Forest, said in a prepared statement.
Nader noted that it's also important to understand distinct patterns of social stress-related brain activity that may increase attraction to cocaine in vulnerable people. Understanding these stress-related brain changes may also help in the development of treatment and prevention methods for people with disorders such as anxiety and depression that can be caused by chronic stress.
The U.S. National Institute on Drug Abuse has more about drug abuse and addiction.
-- Robert Preidt
SOURCE: Wake Forest University Baptist Medical Center, news release, April 6, 2008
All rights reserved