title: Hormonal mechanisms involved in the control of oestrous cycle duration by the odour of urine in the rat.
abstract: The mechanisms involved in the reduced cycle duration following exposure to the odour of urine were studied in natural and experimental 5-day cyclic female Wistar rats. A decrease in the rate of ovarian progesterone secretion from the morning of dioestrus I to that of dioestrus II was observed in females whose cycle duration was reduced from 5 to 4 days following exposure to the odour of rat urine. No decrease in ovarian progesterone secretion occurred in females maintaining a 5-day cyclicity despite exposure to this odour. An increase in follicular growth was noted in females with cycle duration reduced from 5 to 4 days, when compared with those maintaining a 5-day rhythm. As a result of exposure to the odour of urine no reduced cycle duration occurred in females with cycles lengthened from 4 to 5 days as a result of progesterone injection on dioestrus I of 4-day cycles. Hence the decrease in ovarian progesterone secretion, induced by exposure to the odour of urine, is considered to cause a speeding up in follicular growth, thereby reducing oestrous cycle duration in 5-day cyclic rats.
mesh_terms: D000818:Animals; D004971:Estrus; D005260:Female; D009812:Odorants; D006080:Ovarian Follicle / Q000254:growth & development; D010053:Ovary / Q000378:metabolism*; D011247:Pregnancy; D011374:Progesterone / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014556:Urine
chemical_list: D011374:Progesterone