Phenylephrine and ECS-induced retrograde amnesia.

Phenylephrine is a nonselective alpha-receptor agonist. This study examined whether the administration of phenylephrine immediately before electroconvulsive shocks (ECS) attenuated ECS-induced retrograde amnesia. Adult male Wistar rats received phenylephrine (0.25 mg/kg i.p.) or saline 3 min before each of three once-daily true or sham ECS. Retention of pre-ECS learning was studied 1 day after the ECS course using a passive avoidance task. Phenylephrine increased seizure duration in ECS-treated rats, and also enhanced recall in both true and sham ECS groups. The latter finding suggests that phenylephrine nonspecifically improves cognitive functions, perhaps through adrenergic mechanisms that improve memory consolidation and storage. Since phenylephrine increases blood pressure, its cognitive effects also weaken the hypothesis that ECT-induced cognitive impairment results from the seizure-related hypertensive surge.