AJP - Endocrinology and Metabolism, Vol 247, Issue 6 808-E814, Copyright © 1984 by American Physiological Society
Transient development and function of rabbit corpora lutea after hypophysectomy
K. C. Yuh, C. H. Bill 2nd and P. L. Keyes
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.
