EMOTIONAL BUT NOT PHYSICAL STRESS ENHANCES INTRAVENOUS COCAINE SELF-ADMINISTRATION IN DRUG-NAIVE RATS

Involvement of stress in the etiology of drug dependence has received little attention. In the present study a number of behavioural manipul ations were applied and examined for an effect on intravenous cocaine self-administration in drug-naive rats with no prior training in lever press responding. Self-administration rate was measured during five co nsecutive daily sessions. Stress reduction by handling rats daily for two weeks prior to testing for self-administration did not affect coca ine self-administration. Acute physical stress was induced either by a hot plate or by repeated footshocks, and emotional stress was induced by forcing rats to witness another rat being subjected to repeated fo otshocks. These stressors were applied immediately prior to each cocai ne self-administration session. Emotional but not physical stress enha nced the rate of cocaine self-administration. It is concluded that emo tional distress may increase the rewarding effects of cocaine and may render an individual more susceptible to development of drug dependenc e.