Short-term dynamic culture of rat testicular fragments as a model to assess effects on steroidogenesis--potential use and limitations

Abstract

Short-term dynamic culture of rat testicular fragments was evaluated as a model to assess effects on steroidogenesis. A total of 11 compounds differentially affecting testosterone synthesis (aminoglutethimide, ketoconazole, danazol, flutamide, diethylstilbestrol, genistein, butylparaben, nonoxynol-9, dimethoate, RU 486, and cadmium chloride) were used to explore the performance of the assay. Testosterone secretion into the medium and testosterone retained in tissue fragments was determined as a measure of steroidogenesis. Three independent experiments per compound were performed. The known in vitro inhibitory properties of most compounds could be detected. Whenever significant inhibition of testosterone synthesis was observed, low effect concentrations for a given compound differed frequently only by a factor of <or=3.3, maximally by a factor of 10 from each other across the three experiments and besides a decrease of testosterone concentrations in the medium, corresponding reduction of testosterone levels in tissue fragment was obtained. On the other hand, despite the use of high concentrations, danazol and genistein were unexpectedly tested negative, and considerable variability of testosterone production within control and treatment groups of individual experiments were frequently observed. In contrast to cellular systems, specific assessment of cytotoxicity to the testosterone producing Leydig cells was not possible, effects requiring prolonged incubation times could be overlooked, and the observed variability of hormone production necessitates a considerable number of individual incubations per treatment group. On the whole, short-term dynamic culture of rat testicular fragments offers limited potential to assess effects on steroidogenesis by compounds of moderate to strong potency that directly interfere with steroidogenic enzymes or rapidly induce cytotoxicity.