REPEATED INESCAPABLE STRESS PRODUCES A NEUROLEPTIC-LIKE EFFECT ON THECONDITIONED AVOIDANCE-RESPONSE

This study tests the hypothesis that the dopaminergic system mediates a restitutive response by decreasing its own activity in the face of e vents like persistent inescapable stress that threaten to interrupt or ganized mental activity. It is well established that neuroleptic drugs inhibit the conditioned avoidance response (CAR), but not the escape response, probably via a reduction in subcortical dopaminergic activit y. We trained rats to perform the CAR and then subjected them to acute and chronic stress to determine whether this would result in inhibiti on of the CAR. Rats subjected to tu,ice daily tailshock stress for 8 d ays showed inhibition of the CAR and a reduction in dopamine (DA) util ization in the nucleus accumbens. These findings are compatible with t he hypothesis that an endogenous DA-dependent mechanism exists that mi mics neuroleptic effects in the face of repeated stress. In humans thi s response may serve as a protection against psychotic decompensation from chronic endogenous or exogenous insult.