Intravenous gestational cocaine in rats: effects on offspring development and weanling behavior

Pregnant rats were injected with cocaine (CN; 6 mg/kg) or an equal volume of saline (SAL), via the tail vein, on gestation days 8-20. A third group was untreated (UT). Maternal weight gain was not affected by dam treatment despite slight differences in food intake. Litter characteristics (e.g., litter size, pup weight) did not differ among groups. Indices of fetal mortality were not affected by the treatments. Developmental tests, initiated on postnatal day (PND) 2, indicated slight delays in the negative geotaxic response and eye opening in cocaine-exposed pups. Open-field and tail-flick tests were performed on PND 21. Pups were acutely injected with cocaine (10 mg/kg, IP), saline, or received no treatment before placement in a novel open field; morphine (1.5 mg/kg, SC) or saline was injected prior to the tail flick test. Pups from CN dams exhibited a significant decrease in spontaneous exploratory behavior compared to both controls, and a time-dependent increase in rearing compared to pups from UT dams. The acute cocaine injection prior to placement in the open field did not alter locomotion or rearing among dam treatment groups. However, the acute cocaine injection did increase stereotypy ratings for female pups from CN dams compared to similarly treated males, and females from SAL and UT dams. No differences were observed among groups in the tail-flick test. These data suggest that the IV route of administration provides a viable method of cocaine delivery in pregnant rats, and provides further evidence of the developmental and behavioral teratogenicity of prenatal cocaine exposure.