Prenatal cocaine treatment reduces haloperidol-induced catalepsy on postnatal day 10

This study examined the influence of prenatal cocaine on subsequent cataleptic responses to the dopamine (DA) receptor antagonist haloperidol. Pregnant Sprague-Dawley rats were given daily injections of 40 mg/kg cocaine HCl SC from gestational day 8 to 20. Control animals were either uninjected and fed ad lib or saline-injected and pair-fed to the cocaine dams. On postnatal day (PD) 1, litters were culled to eight (sex-balanced if possible) and fostered to surrogate mothers. On PD 10 and PD 15, one male and one female from each litter were injected SC with 1 mg/kg haloperidol or vehicle. Each pup was tested for catalepsy 1 h later by placing its forepaws on an elevated, horizontally oriented dowel rod and recording the latency to remove at least one paw from the dowel. On PD 10 but not PD 15, haloperidol administration produced significantly less catalepsy in the cocaine-exposed subjects than in the untreated controls. No other group differences were observed. These results suggest that prenatal cocaine may alter either the DA system or any of several other neurotransmitters known to influence neuroleptic-induced catalepsy.