EFFECTS OF PRENATAL TESTOSTERONE ON SEX AND AGE-DIFFERENCES IN BEHAVIOR ELICITED BY STIMULUS PUPS IN THE RAT

From Days 14 to 19, pregnant Wistar rats were treated with either 2 mg of testosterone propionate (TP) or vehicle. Thirty-, 60-, and 90-day- old offspring were tested individually during 15 min daily on 4 days w ith a stimulus litter, and pup-oriented behaviors observed in oil grou ps were eliminated by TP treatment, which affected mainly females. Add itionally, TP treatment increased the frequency of self-grooming and d ecreased the time spent near the pups and the frequency of sniffing an d pawing only at 90 days of age. Hiding behavior only occurred at 30 d ays of age, while pawing near the pups and lying-down behavior was obs erved mainly in adults. Results show that sex differences in behavior are present before subjects become sensitized to show evident maternal behavior, and suggest that prenatal androgens play an important role in the manifestation of these sex differences and that its effects dep end on developmental factors. (C) 1998 John Wiley & Sons, Inc.