سهم بالقوه استروژن قبل از تولد برای تمایز جنسی از ترجیحات همسر در موش ها

The neural mechanisms controlling sexual behavior are sexually differentiated by perinatal actions of gonadal hormones. We recently observed using female mice deficient in alpha-fetoprotein (AFP-KO) and which lack the protective actions of AFP against maternal estrogens, that exposure to prenatal estrogens completely defeminized their potential to show lordosis behavior in adulthood. Therefore, we determined here whether mate preferences were also affected in female AFP-KO mice. We observed a robust preference for an estrous female over an intact male in female AFP-KO mice, which were ovariectomized in adulthood and subsequently treated with estradiol and progesterone, whereas similarly treated WT females preferred the intact male over the estrous female. Gonadally intact WT males preferred the estrous female over the male, but only when visual cues were blocked by placing stimulus animals behind opaque partitions. Furthermore, when given the choice between an intact male and a castrated male, WT females preferred the intact male, whereas AFP-KO females showed no preference. Finally when given the choice between an estrous female and an ovariectomized female, WT males preferred the estrous female whereas AFP-KO females preferred the ovariectomized female or showed no preference depending on whether they could see the stimulus animals or not. Taken together, when AFP-KO females are tested under estrous conditions, they do not show any male-directed preferences, indicating a reduced sexual motivation to seek out the male in these females. However, they do not completely resemble males in their mate preferences suggesting that the male-typical pattern of mate preferences is not solely organized by prenatal estrogens.

When in breeding condition, male and female mammals usually seek out and mate with opposite sex conspecifics. It has been well established that the neural mechanisms controlling mate preference are sexually differentiated by the perinatal actions of sex steroid hormones (Bakker, 2003). Thus, a female-directed preference develops in male rats under the early (perinatal) influence of estradiol derived from neural aromatization of testosterone (Bakker et al., 1993, Bakker et al., 1996a and Bakker et al., 1996b). Male rats treated neonatally with 1,4,6-androstatriene-3,17-dione (ATD), a specific inhibitor of the aromatase enzyme, failed to show a preference for an estrous female when given a choice between an estrous female and a sexually active male in a three compartment box, whereas normal males clearly preferred the vicinity of the estrous female. In fact, such neonatally ATD-treated male rats preferred the vicinity of the sexually active male, in particular following estradiol treatment in adulthood (Bakker et al., 1993, Bakker et al., 1996a and Bakker et al., 1996b) suggesting that their mate preferences had not been masculinized.