Swimming Immobilization as a Behavioral Indication of the Ontogeny of Catecholaminergic Function

摘要

Half of each of 8 litters was given a 5 min swimming evaluation at 26, 31, 36, 41, 46, 51 and 60 days of age. The remaining half of each litter was tested only at 41 days as a control for experience. During each 5 min swim, the rat's behavior was scored as active (0) or immobilized (1) at 15 sec intervals. Immobilization scores were highest on days 36 and 41 in the males and on day 36 in the females, indicating a peak in immobilization during the periadolescent period. Twelve additional litters of rats/age group were evaluated at 26, 36, or 51 days of age. Within each litter, saline, 1.0 mg/kg d-amphetamine sulfate, or 0.1 mg/kg haloperidol was administered to 1 male and 1 female one hour prior to testing. The rats were given a 5 min swimming evaluation. The results showed that immobilization was increased by haloperidol and reduced by amphetamine across all ages. Drug-induced changes in immobilization response, however, did not indicate periadolescent hyosensitivity to amphetamine or hypersensitivity to haloperidol as reported for other endpoints.