Hormonal control of receptivity, proceptivity and sexual motivation

Abstract

The results of three experiments using ovariectomized female rats are reported. In each experiment, females were individually tested in large arena with a partner (or partners) tethered so as to give the unrestrained female control over the occurrence of social interaction. In the first experiment we show that ovariectomized females will repeatedly approach a sexually active male and allow themselves to be mounted. Other forms of female initiated contact are common. These include “grooming” and “nosing” the male, crawling over or under the male, the “push-past” the male, genital sniffing, and following the male. For convenience we refer to these as feminine social contacts. Treatment with ovarian hormones induces sexual receptivity, increases the frequency with which females approach males, and increases the display of sexual soliciting behaviors such as hopping and darting. In this setting the frequency of feminine social contacts is decreased. In a second experiment we show that hopping/darting is frequently displayed by intensely receptive females when they are tested with sexually active males, but these beahviors are almost never displayed in the presence of either a sexually passive male or a female. The frequency of feminine social contacts varies predictably with the setting: contact frequency is low when receptive females are tested with active males; contact frequency is high when females are tested with a passive male or a female. In the third experiment we used a preference test paradigm to measure sexual motivation. This involved testing a female with a sexually active male and a sexually inactive castrate at the same time. Treatment with ovarian hormones increases a female's preference for the sexually active male over the castrate, and by this criterion hormonal stimulation can be said to increase sexual motivation. The results of this experiment, using a very simple test for sexual motivation, form the basis for a forthcoming series of papers dealing with the effects of brain damage upon reflexive and volitional components of feminine sexual behavior.