AJP - Endocrinology and Metabolism, Vol 238, Issue 5 458-E462, Copyright © 1980 by American Physiological Society
Effect of serum sex steroids on pituitary LH response to LHRH and LH synthesis
L. K. Tang
To determine the factors responsible for the sex difference in luteinizing
hormone (LH) response to luteinizing hormone-releasing hormone (LHRH)
observed earlier in pituitary cultures, we examined the effects of serum,
17 beta-estradiol, and testosterone on pituitary LHRH-responsiveness and LH
synthesis. Cultures prepared from female rats were maintained in medium
supplemented with serums. Dextran-coated charcoal (DCC) adsorption of
female rat serum reduced, whereas DCC adsorption of male rat serum
increased the pituitary LHRH-responsiveness, indicating the existence of
stimulatory factor(s) in female rat serum and inhibitory factor(s) in male
rat serum. Readdition of testosterone to DCC female rat serum significantly
reduced LH release in response to LHRH (78-32% of the control) without
affecting total LH content. Readdition of 17 beta-estradiol to DCC female
rat serum significantly increased the LH release in response to LHRH,
cellular LH content, and 3H-labeled precursor uptake and incorporation into
immunoprecipitable LH. These results indicate that the sex difference in
LHRH responsiveness may be attributed to the stimulatory effect of 17
beta-estradiol and the inhibitory effect of testosterone on the LH cells.
