Impaired memory consolidation in rats produced with beta-adrenergic blockade

Despite abundant evidence that systemic administration of adrenergic drugs and hormones can produce retrograde memory enhancement, the literature cont ains no clear demonstration that postlearning systemic administration of ad renergic antagonists produces retrograde amnesia. Here we demonstrate retro grade amnesia for a stressful learning task (a spatial water maze) with sys temic administration of the beta -adrenergic antagonist propranolol (5 mg/k g). The amnesic effect of the drug depended on the degree of learning in th e subjects: Propranolol caused a robust retrograde amnesia in "good learner s," but did not significantly affect memory in "poor learners." The finding s provide critical additional support for the hypothesis that postlearning adrenergic activation modulates memory consolidation processes after emotio nally stressful events and help explain previous failures to detect memory impairment after systemic administration of adrenergic blocking drugs. (C) 2000 Academic Press.