Atropine Sulfate Impairs Performance on an Overtrained Spatial Task in a Dose-Dependent Fashion

摘要

Twelve rats were trained to learn the location of a spatially fixed platform hidden in a Morris maze. Accurate navigation was rewarded by escape from the water on to the platform. Asymptotic performance was achieved over six training days (10 trials/day). Then retention of the spatial task was assessed 30 minutes after treatment with 5, 25, 50, 75 or 100 mg/kg, ip, atropine sulfate or the equivalent volume of saline. There was a significant, dose-dependent, drug effect on escape latency, swim distance, swim speed and swim path measures of spatial performance. There was no significant drug effect on heading error; atropinized animals swam directly toward the escape platform over the first 12 cm of their swim path. However, treatment with atropine sulfate significantly disrupted the usual, direct swim lath used to reach the hidden escape platform. Atropinized animals frequently swam within a 30 cm wide alley directly the platform but used one on more 360 loops to locate the platform. We suggest that cholinergic blockade may significantly disrupt the processing of distal visual cues which rats use in place navigation tasks. Keywords: Nerve blocking, Cholinesterase inhibitors, Spatial retention. (AW)