Effect of hexachlorophene intoxication on learning in rats

Neurotoxicity in the form of hindlimb paralysis is known to be associated with brain lesions characterized by vacuolation of the white matter following hexachlorophene (HCP) intoxication; these paralytic and histopathological effects are reversible with time after discontinuance of HCP exposure. The rates of acquiring a bar-pressing escape and avoidance behavior were measured in female rats after recovery from paralysis following daily oral dosing with HCP (25 mg/kg). Learning deficits were seen as a delay in reaching a 90% escape performance level, as an increase in the number of sessions required to reach a 50% avoidance criterion, as an increase in training time needed to transfer from escape to avoidance responding, and by an increase in the number of sessions needed to reach a maximum level of avoidance behavior over a 35-session period. Peak responding eventually reached a level comparable to controls only after prolonged periods. Brain lesions seen 2-3 months after HCP intoxiciation correlated with the lag in learning ability but not with the maximum avoidance acquisition before sacrifice. These results indicate a long-lasting behavioral deficiency following neurotoxicity which is slowly reversible.