Dependence of gonadotropin-induced steroidogenesis upon RNA and protein synthesis in the interstitial cells of the rat testis

Abstract

The effects of inhibitors of RNA and protein synthesis upon gonadotropic stimulation of testosterone and cyclic AMP production by the Leydig cellwere investigated in vitro with enzyme-dispersed interstitial cells of the rat testis. The testosterone response to human chorionic gonadotropin was abolished by cycloheximide and puromycin, and was markedly reduced by actinomycin D and cordycepin. During 3-h time studies, cycloheximide caused complete inhibition of subsequent steroid production when added at times up to 90 min after the commencement of incubation with human chorionic gonadotropin. Actinomycin D did not completely abolish the testosterone response when added at zero time, and became progressively less effective when added at later times during the incubation period. The stimulation of steroidogenesis by dibutyryl cyclic AMP was also completely abolished by cycloheximide and puromycin, and was significantly reduced by acinomycin D and cordycepin. By contrast with the marked inhibition of steroid production by cycloheximide and actinomycin D, the formation of cyclic AMP during human chorionic gonadotropin stimulation was relatively unaffected by either inhibitor. These results indicate that the stimulation of testosterone production by the Leydig cell in response to gonadotropins and dibutyryl cyclic AMP is dependent upon the synthesis of new RNA and protein moleucles. Thus, effects of gonadotropin and cyclic AMP upon both transcriptional and translational processes appear to be essential intermediate steps in the activation of testicular steroidogenesis. The rapid and complete abolition of subsequent steroid synthesis following addition of cycloheximide or puromycin to human chorionic gonadotropin-stimulated interstitial cells suggests that a relatively labile protein is formed during gonadotropin action.