Timing of sexual receptivity and the release of gonadotrophins during puberty in female rats.
In about 60% of rats that were paired with fertile males before vaginal opening, vaginal opening occurred between 15:00 and 21:00 h under controlled lighting conditions (lights on 06:00-18:00 h). No rats mated before 12:00 h or after 03:00 h. Most of the rats (52/82) mated within 3 h after vaginal opening. About 90% of the rats that were paired with fertile males before vaginal opening mated and most conceived. Serum LH and FSH levels rose from 14:00 h to a peak at 18:00 h, whereas hypothalamic LHRH content suddenly decreased by 18:00 h. This study shows that the timing of sexual receptivity, ovulation and the release of gonadotrophins during puberty are similar to those at pro-oestrus in adult rats and suggest that the diurnal rhythm of hormonal changes plays an important role in timing of the first oestrus.
D000818:Animals; D002940:Circadian Rhythm; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D010060:Ovulation; D051381:Rats; D011919:Rats, Inbred Strains; D012726:Sexual Behavior, Animal; D012741:Sexual Maturation
D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone