Regulation of androgen biosynthesis by internal and anthropogenic compounds in frogs

LANGLOIS, V.S.; FLOOD, D.E.K.; FERNANDINO, J.I.; MATHIEU-DENONCOURT, J.; BISSEGGER, S.

Qerétalo

Congreso; 2nd Meeting of the North American Society for Comparative Endocrinology; 2013

NASCE

Over the past years, our research group has been investigating the regulation, function and disruption of testosterone reduction pathways in amphibians. We are particularly interested in the steroid 5α-reductases (srd5α) involved in converting testosterone to the potent androgen 5α-dihydrotestosterone (5α-DHT). Failure of these enzymes to synthesize 5α-DHT has resulted in adverse reproductive effects (e.g., steroid-related transcriptional disruption and gonadal feminization) at metamorphosis. Furthermore, changes in thyroid hormone (THs) levels have also shown to alter transcription of srd5α. Novel promoter analysis demonstrated the potential for a direct and vertebrate-wide crosstalk at the transcriptional level in mouse (Mus musculus), Western clawed frog (Silurana tropicalis), and medaka (Oryzias latipes) between TH and androgen axes. A comprehensive literature review revealed that THs would also have considerable influence in the sexual ontogeny of male vertebrates, through direct interactions with select sex-determining-genes and regulation of gonadotropin production in the hypothalamus-pituitary-gonad axis. Cumulative evidence from previous studies, coupled with novel promoter analysis suggests mechanisms for a more direct crosstalk between TH and male reproductive axis across vertebrate species. This presentation will highlight the importance of srd5α for normal male amphibian development and will focus on the putative regulation of srd5α by THs.