A fostering study of the effects of prenatal cocaine exposure: II. Offspring behavioral measures.

The impact of rearing condition was assessed in Sprague-Dawley dams given 40 mg/kg cocaine (C40) or saline (LC control) subcutaneously (SC) from gestational days 8-20 and their offspring. Treated pups reared by their biological dams (LC/LC; C40/C40), treated pups reared by surrogate dams (FOS/LC; FOS/C40), and foster pups raised by treated dams (LC/FOS; C40/FOS) were examined. On postnatal day 7 (P7), pups received either 0 (unpaired) 2, 3, or 4 pairings of an odor and footshock and were tested for their aversion to this odor. Foster and LC pups, regardless of rearing condition, exhibited significant odor aversions following either 2, 3, or 4 training trials. In contrast, C40 pups reared by surrogate dams required 4 trials to acquire the aversion, and C40 pups reared by their own dams did not exhibit conditioning even after 4 trials. At P17, no differences were seen among the groups in the aversion formed to an auditory or an olfactory stimulus that was paired with footshock. At P60, shock-elicited aggression among pairs of siblings was examined. Regardless of prenatal exposure condition, offspring reared by dams given cocaine showed a decreased latency to the first aggressive contact, an effect that was evident without any alteration in shock sensitivity. Together these data suggest that being reared by a dam previously exposed to cocaine has an impact on offspring behavioral function apart from the effects of prenatal cocaine exposure per se. The implications of the data regarding the cognitive performance of pups exposed prenatally to cocaine are also discussed.