Effect of Bovine Testicular Extracts on Plasma Gonadotrophins of X-lrradiated Rats 1

Abstract

Summary

The effect of bovine testicular extracts (bTE) on plasma FSH levels in both castrate and X-irradiated male rats has been examined. Biological activity was demonstrated in 34-day-old, orchidectomized rats with doses ranging from 50 to 250 mg. Testicular weights of X-irradiated rats 49 days after X irradiation were decreased by approximately 67%, whereas the ventral prostate weights were unaffected. Plasma FSH levels (383 ng/ml) increased significantly as a result of X irradiation (873 ng/ml). Plasma LH (51 ng/ml) also rose as a result of X irradiation (93 ng/ml), suggesting that there was some interstitial cell damage or some Sertoli cell damage. Two hundred and fifty milligrams of bTE administered in 4% gelatin given once daily for 3 days suppressed the elevated plasma FSH, but was without effect on plasma LH. Castration and a further 3 days of treatment resulted in a significant postcas-tration suppression in plasma FSH (control = 1942 ng/ml; bTE = 1283 ng/ml), and resulted in a suppression of LH as well. This LH response (control = 453 ng/ml; bTE = 285 ng/ml) is probably due to the large dose of bTE employed. A bovine kidney extract (bKE) was totally ineffective in suppressing FSH or LH when given at a dose of 250 mg/ rat/day in 4% gelatin. These data lend further support to the existence of inhibin, contained in bTE, and to its role as a regulator of FSH in the male. The probable site of origin of inhibin is the Sertoli cell.

We wish to thank Robert Paige, Steven Ray Coleman, A. Trent Williams, Todd Himelberger, Neil Bercow (NSF Secondary Science Training Program), William Vivian, and Harold Jones III, for their assistance. The testes used in this study were obtained from Sunnyland Foods, Inc., Dothan, Alabama through the kind cooperation of Mr. B. Braswell. Also, we thank Dr. Marc E. Freeman for his assistance and criticism, Ms. Linda Derby for her preparation of the manuscript, and Mrs. Ethel Lipner and Mrs. Sally Chapman for their technical assistance. We gratefully acknowledge research support from the Department of Biological Science, Florida State University and from the Tallahassee, Sopchoppy, and Gulf Coast Marine Biological Association. M. E. R. was the recipient of a Grant-in-Aid of Research from Sigma Xi, the Scientific Research Society of North America.