Abstract
Drug effects on behaviour are closely related to the temporal patterns of their administration. Numerous studies have demonstrated that regular (daily) versus intermittent dosing of any drug can determine whether tolerance or sensitization is developed. The aim of this study was to examine if daily (10 days) or intermittent (every other day and every two days) administration of haloperidol (0.75 mg/kg, ip) could affect differentially to catalepsy of male (experiment 1) and female mice (experiment 2). Catalepsy was measured by means of the 'bar test', being evaluated 120 minutes after the last administration of haloperidol or saline. In both experiments, as compared with controls, catalepsy increased significantly in mice treated with a single injection of haloperidol, as well as in the groups treated with haloperidol intermittently, although a marked tolerance to haloperidol-induced catalepsy after daily administration of the drug was observed. However, only the group of female mice treated with haloperidol every two days showed significantly more catalepsy than those treated daily or every other day, suggesting that the effect of several schedules of drug administration can affect differentially to male and female mice.
