Effects of withholding food for 0-72 h on mating, pregnancy rate and pituitary function in female rats.
Food was withheld from female rats for 0-72 h at various stages of the oestrous cycle. Withholding food for periods of 24 h ending at 12:00 h on the day of pro-oestrus reduced the mating rate from 61 to 25% (P less than 0.05) but not the pregnancy rate of those rats that mated. Fasting for 24 h ending at 18:00 h on the day of pro-oestrus reduced the pregnancy rate from 82 to 18% (P less than 0.05) without affecting the mating rate and a 48-h fast starting at 12:00 h on the day of pro-oestrus reduced the pregnancy rate from 82 to 25% (P less than 0.05). Withholding food for 23 h ending at 17:00 h on the day of pro-oestrus prevented the LH and prolactin surges normally present at 17:00 h on this day. The treatments had no apparent effect on the ability of the adenohypophysis to release LH in response to injections of GnRH. When ovariectomized female rats fasted for 0-72 h and given 2 injections of oestradiol dibenzoate to test the ability of the hypothalamus to respond to an increasing plasma oestradiol concentration by stimulating the release of LH, a fast for 24 h reduced and a fast for 72 h completely prevented LH release.
D000818:Animals; D002369:Castration; D003307:Copulation; D004958:Estradiol / Q000494:pharmacology; D005246:Feedback; D005260:Female; D005306:Fertilization; D005508:Food Deprivation; D007031:Hypothalamus / Q000187:drug effects; D007986:Luteinizing Hormone / Q000378:metabolism; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D011247:Pregnancy; D011359:Proestrus; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D010906:Pituitary Hormone-Releasing Hormones; D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone