The behavioral response to novelty is altered in rats neonatally exposed to cocaine

It has recently been suggested that the effects of in utero cocaine exposur e may result in subtle deficits related to a challenging environment, inclu ding exposure to novelty or stress. This study used a neonatal drug-exposur e model to examine the behavioral response to a novel environment in rodent s. Subjects were artificially reared (AR) from postnatal Days 4-10. There w ere four treatment groups; AR 40 mg/kg/day cocaine, AR 20 mg/kg/day cocaine , AR control group receiving no drug, and a normally reared control. In Exp eriment 1, subjects were tested for their preference of maternal home-cage or clean wood-chip odors in a T-maze on postnatal Day 15. Subjects from all treatment groups preferred the maternal odor. In Experiment 2, subjects we re habituated to four familiar odors and tested with a novel odor in an ope n field (postnatal Days 16-21). Neonatal exposure to 20 mg/kg/day cocaine l ed to an overall increase in exploratory behavior during testing, whereas 4 0 mg/kg/day did not, supporting the hypothesis that developmental exposure to cocaine at some doses may alter the offspring's response to a changing e nvironment. (C) 1999 John Wiley & Sons, Inc.