Serum LH Suppression by Estradiol but not by Testosterone or Progesterone in Wethers1

Publisher Website
Google Scholar
Abstract
The objective of this experiment was to determine the effect of steroids, previously shown to depress serum luteinizing hormone (LH) in rams, upon serum LH in orchiecto-mized sheep. Accordingly serum LH concentration was monitored during the intravenous injection of testosterone, progesterone or estradiol. Neither testosterone at rates of 12.5, 125 or 1,250 jug/hr nor progesterone at 125, 1,250 or 12,500 Aig/hr significantly depressed LH during an 8-hr injection period. Estradiol, however, injected for 12 hr at only 1 jUg/hr, depressed LH from 22 ng/ml to 11 ng/ml within 4 hours. Although the temporal response to this low dose of estradiol may have been slower, the depression in serum LH concentration appeared to be as great with 1 jUg/hr as with 12 Mg/hr indicating an all or none response. Two of the three steroids reported to depress serum LH in rams failed to do so in wethers. Thus, the steroid signals available for acute control of LH in this animal model are more limited. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.