Endocrinology, Vol 112, 586-591, Copyright © 1983 by Endocrine Society
Multiple mechanisms of regulation of estrogen action in the rat uterus: effects of insulin
AM Rojas and J Steinsapir
Eosinophils appear in the rat uterus in the presence of estrogen. The level
of these cells in the uterus depends on the number of blood eosinophils.
Insulin is an eosinopenic hormone in the blood and, therefore, could
regulate estrogenic responses mediated by these cells in the uterus.
Estrogen-induced uterine edema and eosinophilia at doses of 0.01,. 0.1, 1,
10, and 30 micrograms 17 beta-estradiol (E2)/100 g BW are inhibited by
insulin. Estrogen binding by uterine eosinophils in vitro decreases in the
presence of insulin, suggesting another explanation for the observations in
the uterus in vivo. Injection of insulin alone or in combination with 0.01,
0.01, 0.1, or 1 microgram E2/100 g BW increases uterine RNA and protein
contents by 6 h. Inactive insulin does not modify any of these stimulatory
effects of estrogen. The results support the idea of two separate receptor
systems for estrogens in the rat uterus: the eosinophil receptor system,
which mediates estrogen-induced uterine edema, and the cytosol-nuclear
receptor system, which mediates estrogen-induced uterine RNA and protein
syntheses.
