Intact females: effects of estrous stage on reproductive behavior (top panel) and physiology (bottom panel) in sham-GDX females (D, diestrus-1; P, proestrus; E, estrus). Top panel: lordosis quotient, frequency of lordosis behavior shown by females when mounted by a male; each bar is the mean + 1 SEM of six to ten rats. Bottom panel: weight of the uterus, a steroid-sensitive organ; each bar is the mean + 1 SEM of six to eight organs. *Significantly different from sham-D, P ≤ 0.05, Student–Newman–Keuls.