Failure of acute cocaine administration to differentially affect acoustic startle and activity in rats prenatally exposed to cocaine.

Pregnant rats were administered 40 mg/kg of cocaine hydrochloride subcutaneously on gestation days 14 through 21. Rats in one control group were pair-fed to the cocaine group and injected with the saline vehicle during the dosing period, while an untreated control group was simply weighed throughout pregnancy. Maternal weight gain was reduced 13% in the cocaine group and pair-fed controls, but the offspring did not differ in their numbers or growth compared to the untreated controls. The offspring were examined between postnatal days 80 and 96 in tests of the acoustic startle response and open field behavior immediately following acute administration of 0, 5, or 10 mg/kg of cocaine. The acute dosages of cocaine increased the startle response and increased behavior in the open field. There was no evidence that the prenatal treatment altered the baseline in either of these tests. Adult rats exposed prenatally to cocaine entered more quadrants in the open field and reared more frequently than the other groups following the 10 mg/kg dosage of cocaine. However, there was no evidence of an effect of prenatal treatment among the groups administered the 5 mg/kg dosage in the open field test, nor was there a systematic effect of prenatal treatment on the acute effects of cocaine in the acoustic startle test. These data do not provide evidence that prenatal exposure to cocaine can produce persistent changes in the neural systems with which it interacts in the adult.