J. Anim Sci.
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J. Anim Sci. 1977. 44:0078-83.
© 1977 American Society of Animal Science
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Serum LH Suppression by Estradiol but not by Testosterone or Progesterone in Wethers1

Lee A. Edgerton2 and Clifton A. Baile3

Applebrook Research Center, Smithkline Corporation West Chester, PA 19380

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.

Footnotes

1 The authors express thanks to Dr. L. E. Reichert who supplied purified LH (LER-1056-C2 and LER-1072-2) for iodination, Dr. John G. Pierce who supplied purified bovine TSH and the National Institute of Arthritis and Metabolic Diseases of NIH who supplied other hormonal standards listed in table 2. The authors gratefully acknowledge Ms. P. Kraeer, Mr. D. Lewis and Mr. H. Wells for their assistance with animal care, sample collection and radioimmuno assays.

2 Present address: Department of Animal Sciences, University of Kentucky, Lexington 40506.

2 Present address: New Bolton Center, University of Pennsylvania, Kennett Square 19348.






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