Neural Progestin Receptors: Regulation of Progesterone-Facilitated Sexual Behaviour in Female Guinea Pigs

Besides having influences on a variety of other aspects of behaviour and reproductive physiology, oestradiol and progesterone interact to regulate the display of sexual behaviours during the oestrous cycle of many vertebrate species (Young 1961). In oestrogen-primed female rodents, progesterone both facilitates the display of sexual behaviour and inhibits its further facilitation by progesterone (Morin 1977). The latter effect of progesterone has been called de sensitization (Blaustein 1982a, b). Both of these influences of progesterone are due to actions within the brain. In fact, both effects are seen after intracranial implantation of progesterone within the ventromedial hypothalamic area (Rubin and Barfield 1983, 1984; Morin and Feder 1974a).