Dose- and delay-dependent working/episodic memory impairments following intraventricular administration of ethylcholine aziridinium ion (AF64A).

The present study examined the effects of intraventricular administration of the cholinergic neurotoxin ethylcholine aziridinium ion (AF64A) on performance of a radial arm maze task. Male Sprague-Dawley rats were trained to perform a delayed-nonmatch to sample radial arm maze task in which a 1-h delay was imposed between the fourth and fifth arm selections. Following acquisition, animals were injected bilaterally with AF64A (1.5 or 0.75 nmol/side) or artificial cerebrospinal fluid into the lateral cerebral ventricles and allowed 7 days to recover before behavioral testing resumed. Significant dose- and delay-dependent impairments in the radial maze performance were observed in AF64A-treated rats as evidenced by fewer correct choices following the delay and by more errors to complete the task. Long-term testing in this task revealed significant recovery of memory performance. These findings indicate dose-dependent impairments in memory following intraventricular administration of AF64A and spontaneous behavioral recovery following such insult.