HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Howland, B. E. Articles by Stormshak, F. Search for Related Content PubMed PubMed Citation Articles by Howland, B. E. Articles by Stormshak, F.

Effect of LH and Ovarian Hormones on Pituitary Gonadotropin Activity in Ovariectomized Ewes

Walter Reed Army Medical Center and U. S. Department of Agriculture^,3

² Reprint requests should be addressed to F. Stormshak, Dairy Cattle Research Branch, A.R.S., U.S.D.A., Beltsville, Maryland 20705.

Abstract

A total of 48 mature ovariectomized ewes was assigned to an experiment of 23 factorial design to study the effects of progesterone, estradiol-17β and ovine LH on pituitary gonadotropin activity. Treatment, beginning on day 36 post-ovariectomy, consisted of two levels each of progesterone (0 and 10 mg. per day), estradiol-17β (0 and 500 mcg. per day) and NIH-LH-S-11 (0 and 2 mg. per day). Steroids and LH were administered by subcutaneous and intramuscular injection, respectively, for 5 days followed by autopsy on the sixth day. Exogenous LH increased dry anterior pituitary weight of ewes treated concurrently with progesterone. Injections of estradiol-17β significantly decreased pituitary FSH activity and tended to reduce LH activity while progesterone treatment affected neither gonadotropin. Treatment with LH appeared to depress pituitary FSH activity in non-estradiol-17β treated ewes. Experimental evidence suggests the existence of a pituitary "gonadotropin inhibitory factor," present at least in estradiol-17β treated ewes.

¹ The authors gratefully acknowledge the technical assistance of Miss Helen E. Kelley.

³ From the Department of Neuroendocrinology, Walter Reed Army Institute of Research, Washington, D. C. 20012 and A.R.S. Animal Husbandry Research Division, Beltsville, Maryland 20705.