AJP - Endocrinology and Metabolism, Vol 242, Issue 6 392-E397, Copyright © 1982 by American Physiological Society
Estradiol stimulation of LH response to LHRH and LHRH binding in pituitary cultures
L. K. Tang, A. C. Martellock and J. K. Horiuchi
The relationship between 17 beta-estradiol (E2) stimulation of luteinizing
hormone (LH) response to LH-releasing hormone (LHRH) and E2 effect on LHRH
binding was examined in pituitary monolayer cultures prepared from female
rats. E2 pretreatment significantly (P less than 0.05) augmented the
LHRH-induced LH release to 158-180% of the non-E2-treated controls. The
maximal E2-priming effect could be observed after 1 day of treatment. E2
treatment for 3 days stimulated [D-Ala6]luteinizing hormone-releasing
hormone (LHRHa) binding to about 1.5-fold that of the non-E2-treated
controls without affecting the dissociation constant of LHRH receptor (Kd =
4 X 10(-10) M). The stimulatory effect of E2 on cell proliferation as
determined by [3H]thymidine incorporation was also observed 3 days after
treatment. However, E2 stimulation of LH accumulation in the cultured cells
could be detected as early as 4 h after treatment. These results indicate
that E2-priming effect on pituitary LH response to LHRH is initially
associated with an increase in cellular LH content and later associated
with increases in LHRH binding and in an index of cell proliferation that
may include the LH-producing cells.
