EflFects of Gonadotropins on Cyclic AMP Production by Isolated Seminiferous Tubule and Interstitial Cell Preparations

Abstract

The in vitro effects of FSH and LH on cyclic AMP levels in various types of preparations from rat testes were investigated. LH but not FSH stimulated cyclic AMP production in isolated interstitial cells. Furthermore, FSH did not act synergistically with LH to elevate cyclic AMP levels in interstitial cell preparations. In isolated seminiferous tubules freed of interstitial cells, FSH but not LH stimulated adeny-late cyclase activity. In tubules from normal adult rats, an effect of FSH on cyclic AMP accumulation was detectable only in the presence of theophylline. In tubule preparations from fully regressed hypophysectomized or cryptorchid rats, cyclic AMP levels were elevated by the addition of either FSH or theophylline. When added together, FSH and theophylline acted synergistically to increase cyclic AMP levels. The latter preparations from regressed testes were enriched in Sertoli cells and spermatogonia. Exposure of normal adult testes to irradiation (300 rads) in vivo caused a dramatic reduction in the number of spermatogonia; however, the response of the tubules depleted of spermatogonia to FSH in vitro was comparable to that of tubules protected from irradiation. The results suggest that the Sertoli cell may constitute the principal cell type within the seminiferous tubule which responds to FSH with an increase in cyclic AMP levels. (Endocrinology94: 395, 1974)