Transient development and function of rabbit corpora lutea after hypophysectomy.
The requirement of the pituitary gland and the role of 17 beta-estradiol in the early development of the corpus luteum was investigated in rabbits hypophysectomized the day after sterile mating (day 1). Serum progesterone in hypophysectomized rabbits was normal for 2 days after hypophysectomy. Luteal tissue from hypophysectomized and sham-hypophysectomized rabbits had similar wet weight (4.0 +/- 0.4 vs. 5.3 +/- 0.2 mg/corpus luteum) and similar concentrations of available cytoplasmic estrogen receptor (1.2 +/- 0.2 vs. 1.5 +/- 0.3 fmol/micrograms DNA) and luteinizing hormone (LH) receptor (4.0 +/- 0.2 vs. 6.1 +/- 1.4 fmol/micrograms DNA) on day 4 of pseudopregnancy. Serum progesterone in hypophysectomized rabbits began to decline on day 4 and was undetectable by day 6. Estrogen receptor and luteal weight in hypophysectomized animals also declined after day 4 to low values by day 6, and serum estradiol was undetectable. However, if estradiol was administered by Silastic capsule implanted subcutaneously at the time of hypophysectomy or 3 days after hypophysectomy, serum progesterone, luteal weight, estrogen receptor, and LH receptor were maintained on day 6 of pseudopregnancy. These results indicate that after a preovulatory gonadotropin surge, the function of newly formed corpora lutea is normal for 3-4 days in the absence of pituitary hormones. However, by 4 days after ovulation, estradiol is required to sustain the structural and functional integrity of corpora lutea.
D000818:Animals; D006063:Chorionic Gonadotropin / Q000378:metabolism; D003338:Corpus Luteum / Q000254:growth & development* / Q000473:pathology / Q000502:physiology; D004958:Estradiol / Q000097:blood / Q000494:pharmacology; D005260:Female; D007016:Hypophysectomy; D003341:Luteolysis / Q000187:drug effects; D009929:Organ Size / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D011555:Pseudopregnancy / Q000473:pathology / Q000503:physiopathology; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000378:metabolism; D011974:Receptors, LH; D013696:Temperature; D013997:Time Factors
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D011374:Progesterone; D004958:Estradiol