Thyroid Hormones and Androgens Differentially Regulate Gene Expression in Testes and Ovaries of Sexually Mature Silurana Tropicalis

In a study conducted on sexually mature Western clawed frogs (Silurana tropicalis), researchers investigated the molecular interactions between thyroid hormones (TH) and androgens in testicular and ovarian tissues without the influence of hypophyseal feedback. The tissues were exposed to various hormones including triiodothyronine (T3), iopanoic acid (IOP), and different forms of dihydrotestosterone and testosterone. The results showed that direct exposure to androgens caused an increase in thyroid receptor and deiodinase transcripts in testes, but a decrease in ovaries, indicating sex-specific responses to androgenic compounds. Additionally, certain androgens increased estrogen-related transcription and production in both testes and ovaries, suggesting the activation of alternative pathways for estrogenic metabolites. Thyroid hormones also differentially regulated sex-steroid-related transcription and production. Furthermore, the study examined transcription factor binding sites in the promoter regions of TH- and sex steroid-related genes in S. tropicalis, rodents, and fish through in silico analysis. The findings provide a better understanding of the actions mediated by TH and androgens and highlight the differences in transcriptional effects between sexes in frogs.