Subordinate monkeys more likely to choose cocaine...( WINSTON-SALEM N.C. Having a lower s...),Health

WINSTON-SALEM, N.C. Having a lower social standing increases the likelihood that a monkey faced with a stressful situation will choose cocaine over food, according to a study at Wake Forest University School of Medicine. More dominant monkeys undergoing the same stressful situation had fewer changes in brain activity in areas of the brain involved in stress and anxiety and were less likely to choose cocaine.

Robert Warren Gould, a graduate student in the laboratory of Michael A. Nader, Ph.D., presented the study results Sunday at Experimental Biology 2008 in San Diego. The presentation was part of the scientific program of the American Society for Pharmacology and Experimental Therapeutics (ASPET).

Male cynomolgus monkeys live in a complex social structure in which the social hierarchy is established by physical aggression and maintained by clear signals. A monkey that has established his dominance over another monkey can elicit a subordinate response with no more than a meaningful look.

The researchers exposed four dominant and four subordinate monkeys to a socially stressful situation in which an individual monkey was taken out of his home cage and placed in an unfamiliar cage surrounded by four unfamiliar animals. The monkey was physically safe, but he could see and hear the animals around him engaging in aggressive behavior.

The study was performed twice, in order to ask two different types of questions. The first concerned brain activity caused by the stressful situation. Before being placed in the unfamiliar cage, each monkey had been injected with radioactively labeled glucose. After 40 minutes, each was given a PET brain imaging examination to see which parts of the brain were most active, as determined by which parts were using the most glucose. This type of brain imaging has been used frequently in humans to determine brain activity during various activities and situations. The scan of the individual monkeys
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