Induction of estrous behavior in rabbits by hypothalamic implants of testosterone

Abstract

The brains of adult ovariectomized female rabbits were stereotaxically implanted with small amounts of testosterone propionate (TP) contained within 24-gauge stainless steel tubing. Bilateral implantation of TP into the basal ventromedial-premammillary region of the hypothalamus about 1 mm lateral to the midline resulted in intense estrous behavior within 1-3 days postimplantation. Since previous studies have shown that estrogen placed in this region exerts similar effects on mating behavior, it appears that androgens and estrogens function in the same neurological area to activate patterns of estrous behavior. Implantation of TP into other hypothalamic regions was without effect, and the animals remained anestrous. Ovariectomized females which were estrous as a result of either the injection or implantation of TP were slightly aggressive but showed little male-like mounting activity, suggesting that gonadal steroids activate rather than organize behavior patterns in adult animals.