ADRENAL ROLE IN PROCEPTIVITY AND RECEPTIVITY INDUCED BY 2 MODES OF ESTRADIOL TREATMENT

The effects of chronic estrogen treatment on the receptive and procept ive behaviors of the female rat were investigated using two modes of e strogen administration: estrogen implants and chronic estrogen injecti ons. In addition, the potential mediating role of the adrenal was inve stigated. Animals were either ovariectomized (OVX) or ovariectomized a nd adrenalectomized (ADX-OVX). Each surgery group received three doses of estrogen, via implants in Experiment 1 and chronic injections in E xperiment 2. Each animal was tested with and without progesterone trea tment. Within the range of doses in the two experiments, the effect of estrogen on proceptivity appeared to be dose dependent. However, low estrogen doses were sufficient to maintain a high level of receptivity . These results suggest different mechanisms for the induction of proc eptive and receptive behavior in the female rat. The facilitatory effe ct of progesterone on receptivity was dependent on the estrogen dose f or both modes of administration, but on proceptivity was dependent on the estrogen dose only following chronic estrogen injections. Overall, this study suggests that the adrenal gland is important in the displa y of female sexual behavior elicited by exogenous hormones. The estrog en implant study (Experiment 1) revealed that while the adrenal gland is not necessary for receptive behavior, it is important for the displ ay of proceptive behavior. In addition, with chronic estrogen injectio ns (Experiment 2), progesterone was more effective in elevating procep tivity in ADX-OVX than in OVX females, and ADX-OVX females treated wit h progesterone generally showed less lordosis behavior than OVX female s treated with progesterone. These results suggest that progesterone o f adrenal origin may be important for sexual responding in the female rat.