This study assessed whether changes in production of seminiferous tubule fluid underlie the previously described androgen-dependent changes in protein secretion by seminiferous tubules at stages VI–VIII of the spermatogenic cycle. Testosterone withdrawal was induced in adult rats by administration of ethane dimethane sulfonate (EDS) and temporal changes in lumen area, the volume of seminiferous tubule fluid and testicular interstitial fluid were assessed and compared with the changes in secretion of [35S]methionine-labelled proteins in vitro by isolated seminiferous tubules at stages VI–VIII. Testicular interstitial fluid was reduced by about 50% by day 4 and later after EDS treatment when compared with controls. In contrast, the volume of seminiferous tubule fluid was unaffected at days 3 and 4 but was reduced by about 50% at days 6 and 8 after EDS treatment. In perfusion-fixed control testes, the lumen area of seminiferous tubules at stages VII–VIII was significantly greater than at stages I–VI and IX–XIV. This difference was also evident at 4 days after EDS treatment, but was abolished at 6 and 8 days after treatment. The volume of testicular interstitial fluid was reduced significantly at 3 and 4 days after EDS treatment, but was further reduced (about 50%) at 6 and 8 days. Administration of 25 mg testosterone esters every 3 days to EDS-treated rats prevented all of the changes described above. As the decrease in protein secretion by seminiferous tubules at stages VI–VIII following androgen withdrawal precedes the changes in lumen area and volume of seminiferous tubule fluid, it is concluded that there is differential control of these two androgen-dependent processes. The present data add to the evidence showing that testosterone plays a central role in regulating the production and movement of fluids (and therefore of nutrients) to and within the testis.
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