The role of estrogen and progesterone in the control of preputial gland sex attractant odors in the female rat.

Sexually experienced male rats were used to test the attractiveness of body odors of female rats. The attractiveness of these odors varied with the estrous cycle. Odors from female rats in proestrus were the most attractive to male rats and those from female rats during the darkness hours of diestrus the least attractive. The preputial glands appeared to be the source of these odors for the male rats showed no preference for the odors of proestrous female rats that had been preputialectomized. Administration of 1 microgram estrdiol benzoate (EB) for 5 days increased the attractiveness of body odors of ovariectomized rats. A higher dose of EB (5 microgram) had the same effect when administered for 1 or 5 days although the increase that occurred after 3 days was not significant. A single dose of progesterone (P) (500 microgram) on the other hand, decreased the attractiveness of ovariectomized female odors although no change was seen after 3 days of treatment. A single injection of P also decreased the attractiveness of odors of ovariectomized females that had received EB for 3 days. However, P failed to decrease the attractiveness of odors in ovariectomized females after preputialectomy. We conclude that the preputial glands are an important source of sex attractant odors in the female rat and that the changes in the release of these odors that occur throughout the estrous cycle and pregnancy are controlled by ovarian steroids. While estrogen acts to stimulate the production and release of these odors P appears to inhibit their release.

Effect of alpha-melanocyte-stimulating hormone and ovarian steroids on preputial gland function in the female rat.

Sexually experienced male rats were used to test the attractiveness of preputial gland odours of female rats. The male rats showed a clear preference for the preputial gland odours of hypophysectomized females given oestradiol benzoate (OB) for 3 or 8 days to those of control rats. Progesterone treatment had no effect on the attractiveness of the preputial gland odours of OB-treated hypophysectomized female rats. Administration of alpha-MSH for either 3 or 8 days, on the other hand, increased the attractiveness to male rats of preputial gland odours of OB-treated hypophysectomized females and the presence of progesterone produced no further change. When administered alone alpha-MSH had no effect on the attractiveness of the preputial gland odours. Other pituitary hormones, such as ACTH and prolactin, had no effect on the attractiveness of preputial gland odours of OB-treated hypophysectomized rats when administered for 3 days. An increase in preputial gland size was only seen when OB, progesterone and alpha-MSH were administered together. It would appear that no relationship exists between the size of the preputial glands and their ability to attract male rats. It is concluded that, while alpha-MSH and progesterone may be important in controlling growth of the preputial glands, an interaction between alpha-MSH and oestrogen is more important for regulating the production of sex attractants by the preputial glands.

alpha-Melanocyte stimulating hormone and the release of sex attractant odors in the female rat.

Sexually experienced male rats were used to test the attractiveness of odors of hypophysectomized females the male rats showed a clear preference for 4 days failed to alter the attractiveness of odors of hypophysectomized females and male rats showed a clear preference for the odors of females that had received 10 micrograms EB. Daily administration of 50 micrograms alpha-MSH failed to increase the attractiveness of odors of hypophysectomized females the male rats showed a clear preference for the odors of females that had received 10 micrograms EB. Daily administration of 50 micrograms alpha-MSH failed to increase the attractiveness of odors from females that received 2 microgram EB but was effective in females that had received 10 micrograms EB. However, no effect was seen in female rats that had been preputialectomized. alpha-MSH also increased the attractiveness of odors of posterior hypophysectomized rats in proestrus. Moreover, the reduction in odor attractiveness found after posterior hypophysectomy in female rats in proestrus was almost restored by alpha-MSH treatment. On the other hand, when the alpha-MSH treated posterior hypophysectomized females were in diestrus their odors were less attractive to male rats than those of the untreated controls. A similar reduction in odor attractiveness occurred in alpha-MSH treated posterior hypophysectomized females in proestrus after a single injection of progesterone. These results suggest that in the female rat alpha-MSH has a physiological role in controlling sexual odors from the preputial glands and by interacting with estrogen and progesterone can either enhance or reduce the attractiveness of these odors to male rats.