Androgenic-anabolic steroids blunt morphine-induced c-fos expression in the rat striatum: possible role of beta-endorphin

Self-administration of large doses of androgenic-anabolic steroids (AAS) in a significant portion of the population suggests that these agents are dru gs of abuse. However, acute administration of AAS did not induce striatal i mmediate-early genes (LEG) expression in male rats, indicating that AAS do not share a common mechanism of action with other drugs of abuse. Surveys h ave indicated that people who abuse AAS are more likely to self-administer other drugs of abuse than do people who do not take AAS. in the present stu dy, chronic administration of AAS blunted the striatal c-fos response to mo rphine, indicating that AAS can alter the molecular responses to at least o ne drug of abuse. Chronic administration of AAS also increased the content of P-endorphin in the midline thalamus, suggesting a possible mechanism by which AAS may modulate the response to morphine through regulation of thala mo-striatal neurons. (C) 2000 Published by Elsevier Science B.V. All rights reserved.