Thyroid hormones and androgens differentially regulate gene expression in testes and ovaries of sexually mature Silurana tropicalis

Abstract

A series of ex vivo exposures using testicular and ovarian tissues of sexually mature Western clawed frogs (Silurana tropicalis) were designed to examine molecular mechanisms of thyroid hormone (TH) and androgen crosstalk sans hypophyseal feedback as well as investigate potential sex-specific differences. Tissues were exposed ex vivo to either triiodothyronine (T3), iopanoic acid (IOP), one co-treatment of IOP + 5α-dihydrotestosterone (5α-DHT), 5α-DHT, 5β-dihydrotestosterone (5β-DHT), or testosterone (T). Direct exposure to different androgens led to androgen specific increases in thyroid receptor and deiodinase transcripts in testes (trβ and dio1) but a decrease in expression in ovaries (trβ and dio3), suggesting that male and female frogs can be differently affected by androgenic compounds. Moreover, exposure to select androgens differentially increased estrogen-related transcription (estrogen receptor alpha (erα) and aromatase (cyp19)) and production (estradiol) in ovaries and testes indicating the activation of alternate metabolic pathways yielding estrogenic metabolites. Sex-steroid-related transcription (i.e., steroid 5α-reductase type 2 (srd5α2) and erα) and production (i.e., 5α-DHT) were also differentially regulated by THs. The presence and frequency of transcription factor binding sites in the putative promoter regions of TH- and sex steroid-related genes were also examined in S. tropicalis, rodent, and fish models using in silico analysis. In summary, this study provides an improved mechanistic understanding of TH- and androgen-mediated actions and reveals differential transcriptional effects as a function of sex in frogs.

Intraspecific developmental variation in the life cycle of the Andean Treefrog (Boana riojana): A temporal analysis

“…In B. riojana, the testes begin to differentiate at mid‐prometamorphosis, regardless of absolute ages. This suggests that a minimum level of circulating thyroid hormone is a prerequisite for testicular development in this species (e.g., Wagner, Wajner & Maia, ; Campbell & Langlois, ; but see Duarte‐Guterman, Navarro‐Martin & Trudeau, ). Conversely, it is unclear why a certain absolute age must be reached for ovarian differentiation.…”

Di(2‐ethylhexyl) phthalate induced thyroid toxicity via endoplasmic reticulum stress: In vivo and in vitro study

“…Epidemiological studies have shown that the prevalence of thyroid disease in women was generally higher than that in men in various countries 25,26 . Animal experiments also showed that the thyroid of female animals responded more significantly to exogenous compound under the same exposure conditions 27,28 . Thyroid damage was more severe in females, so we only chose female offspring rats.…”

Association Between Neonatal Thyroid Function and Anogenital Distance from Birth to 48 Months of Age

“…In in vitro studies, THs along with other gonadotropic hormones could inhibit the excessive production of androgens in theca cells isolated from medium-sized follicles ( 40 ). Animal studies have also reported that THs could decrease the expression of steroid 5α-reductase type 2, one androgen-related gene, playing anti-androgen effects in the ovary tissue of female S. tropicalis frogs ( 41 ). Another mechanism that affecting female AGD through estrogenic pathways has also been proposed ( 39 ).…”