Prenatal testosterone exposure elevates maternal aggression in mice.

Pregnant Rockland-Swiss (R-S) female mice were injected with oil, 0.5, 1.0 or 2.0 micrograms of testosterone propionate (TP) on days 12, 14 and 16 of gestation and the maternal aggressive behavior of their resulting female offspring was examined in adulthood. Prenatal exposure to 1 or 2 micrograms of TP, but not 0.5 micrograms of the steroid, significantly increased the number of attacks displayed by parturient mice toward adult male intruders. The behavioral effects on aggression were observed in the absence of effects on external morphology, body weight, or lactational performance. The findings support previous research showing that the development of feminine behavior may be sensitive to prenatal androgens. The possibility that the presence of fetal testosterone augments both male and female aggressive behavior is discussed.