Delayed onset of persistent estrus in aged rats raised from parathyroidectomized mothers.
Descendants of rats possessing lower responsiveness to the removal of the parathyroid gland [4] were examined for the aging process of the hypothalamic-pituitary-ovarian axis. The first generation rats of these descendants were born to mothers parathyroidectomized (Px) on the fifth day of gestation and subsequent generation rats were developed by brother-sister mating without any special treatment. More than 50% of the eighth to tenth generation (F8-F10) offsprings of the Px-rats showed regular 4-day estrous cycles at 15-16 months of age, while nearly 80% of normal F8-F10 rats developed persistent estrus at 13-14 months of age. In 14-15 month-old Px-offspring rats the LH and FSH surges occurred at 1630-1730 h of proestrus to a similar extent as those shown in 3-4 month-old normal rats. The release of LH and FSH following a single injection of luteinizing hormone-releasing hormone (LHRH) in 13 month-old Px-offspring rats was nearly normal, reaching a maximal level at 15 min as in young adult rats. In 13 month-old normal rats, serum LH measured after an injection of LHRH increased progressively until 60 min. The ovaries of the Px-offspring rats were heavier than those of age-matched normal rats and included well-developed corpora lutea and follicles in several sizes. The results suggest a delay in the aging process of the hypothalamic-pituitary-ovarian axis of the Px-offspring rats.
D000375:Aging; D000818:Animals; D002118:Calcium / Q000097:blood; D004958:Estradiol / Q000097:blood; D004971:Estrus; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood; D010053:Ovary / Q000502:physiology*; D010280:Parathyroid Glands / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D051381:Rats
D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D002118:Calcium