TESTOSTERONE AND SPERMATOGENESIS - EVIDENCE THAT ANDROGENS REGULATE CELLULAR SECRETORY MECHANISMS IN STAGE VI-VIII SEMINIFEROUS TUBULES FROM ADULT-RATS

The aim of this study was to investigate the effect of testosterone ma nipulation on the quantitative synthesis and secretion of a number of specific proteins produced by seminiferous tubules (ST) isolated at st ages VI-VIII of the spermatogenic cycle from adult rats. The proteins selected were derived from different cellular sources. ST were isolate d from control rats, from rats treated 4 days earlier with ethane dime thane sulfonate (EDS) to induce complete testosterone withdrawal by th e destruction of the Leydig cells, and from EDS-treated rats injected with testosterone esters (TE) in order to maintain quantitatively norm al spermatogenesis. Two-dimensional sodium dodecyl sulfate polyacrylam ide gel electrophoresis, combined with computerized image analysis, wa s used to analyze S-35-methionine-labeled intracellular and secreted p roteins. Testosterone withdrawal did not affect to any significant deg ree the total synthesis of any of the proteins studied. Similarly, the secretion of the major known Sertoli cell proteins SGP-1 and SGP-2, t ogether with a third putative Sertoli cell protein, all of which appea red to be secreted constitutively, was also not affected to any major degree by EDS treatment. In contrast, the secretion of another probabl e Sertoli cell protein, together with six proteins found to be secrete d by germ cells and one protein that appeared to derive from more than one cellular source, was reduced dramatically by testosterone withdra wal, but was maintained by treatment with EDS+TE. All of the affected proteins appeared to be secreted in a regulated manner. Our results co nfirm that testosterone manipulation has little or no effect on either total protein synthesis by ST, or on the secretion of the major Serto li cell secretory proteins, at stages VI-VIII of the spermatogenic cyc le, but suggest strongly that testosterone regulation of ST protein se cretion at these stages is mediated by an effect on the regulated secr etory pathways. Our findings also demonstrate that the secretion, not only of Sertoli cell proteins, but also of those secreted by germ cell s, is androgen-regulated.