Timing of neonatal testosterone exposure in the differentiation of estrogenic regulatory systems for aggression

Neonatal female CF-1 mice were exposed to testosterone (T) or oil vehicle on Days 1-3, 4-6, or 7-9 postpartum and were tested for the display of male-like aggressive behavior in response to diethylstilbestrol (DES) after ovariectomy during adulthood. The results showed that only the Day 1-3 T treatment established the capacity to exhibit fighting behavior following estrogen administration. These data suggest that sexual differentiation of an estrogen-responsive regulatory system for aggressive behavior occurs during a highly restricted period early in life.