Estrogen action in anterior and ventromedial hypothalamus and the modulation of heterosexual behavior in female golden hamsters

Abstract

Changes in heterosexual patterns of agonistic, marking, and sexual behavior were examined in female hamsters over a three day period following implantation of either estrogen or cholesterol in the hypothalamus. Animals were habituated to large arenas that permit the display of a wide range of behavior. Estrogen implants located in the ventromedial (VMH) but not the anterior (AH) portion of the hypothalamus were effective in facilitating the occurrence of vaginal marking, over a two day estrogen priming period. During this two day period, the exhibition of agonistic behavioral patterns declined significantly. Systemic administration of progesterone elicited sexual receptivity in 75% of the females in the VMH group, in contrast to only 25% in the AH group. Females with hypothalamic implants of cholesterol remained unreceptive following progesterone injections. The results provide important information on the estrogen sites of action at the hypothalamus in mediating heterosexual interactions.