Adrenal role in proceptivity and receptivity induced by two modes of estradiol treatment.

The effects of chronic estrogen treatment on the receptive and proceptive behaviors of the female rat were investigated using two modes of estrogen administration: estrogen implants and chronic estrogen injections. In addition, the potential mediating role of the adrenal was investigated. Animals were either ovariectomized (OVX) or ovariectomized and adrenalectomized (ADX-OVX). Each surgery group received three doses of estrogen, via implants in Experiment 1 and chronic injections in Experiment 2. Each animal was tested with and without progesterone treatment. 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 proceptive and receptive behavior in the female rat. The facilitatory effect of progesterone on receptivity was dependent on the estrogen dose for 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 display of female sexual behavior elicited by exogenous hormones. The estrogen implant study (Experiment 1) revealed that while the adrenal gland is not necessary for receptive behavior, it is important for the display of proceptive behavior. In addition, with chronic estrogen injections (Experiment 2), progesterone was more effective in elevating proceptivity in ADX-OVX than in OVX females, and ADX-OVX females treated with progesterone generally showed less lordosis behavior than OVX females treated with progesterone. These results suggest that progesterone of adrenal origin may be important for sexual responding in the female rat.