Cortisol-induced masculinization: does stress play a role in temperature-dependent sex determination?

HATTORI, RICARDO S.; FERNANDINO, JUAN IGNACIO; KISHI, AI; KIMURA, HIROYUKI; KINNO, TOMOMI; OURA, MIHO; SOMOZA, GUSTAVO M.; YOKOTA, MASASHI; STRÜSSMANN, CARLOS A.; WATANABE, SEIICHI

Hong Kong, China

Congreso; 16th International Congress of Comparative Endocrinology; 2009

Gonadal fate in many reptiles, fish, and amphibians is modulated by the temperature experienced during a critical pedior early in life (temperature-dependent sex determination; TSD). Several molecular processes involved in TSD have been described but how the animals "sense" environmental temperature remains unkwon. We examined whther the stress-related hormone cortisol mediates between temperature and sex differentiation in pejerrey (Odontesthes bonariensis), a teleost fish with marked TSD, and the posibility that it involves glucocorticoid receptor- and/or steroid biosynthesis-modulation. Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperatur (29 ºC; 100% males) consistenly had higher cortisol, 11-ketotestosterone (11-KT), and testosterone (T) levels than those at a feminizing temperature (17 ºC, 100% femlaes). Cortisol-treated animlas had elevated 11-KT and T, and showed a typical molecular signature of masculinization including amh upregulation, cyp19a1a downregulation, and higher incidence of gonadal apoptosis during sex differentiation. Administration of cortisol and a non-metabolizable glucocorticoid receptor (GR) agonist (Dexamethasone) to larvae reared at a "sexually neutral" temperature (24 ºC) caused significant increase in the proportion of males. All results are consistent with a role of cortisol in the masculinization process of pejerrey and provide a direct link between stress and testicular differentiation in a TSD species. The cortisol roles or role during TSD seem(s) to involv both androgen biosynthesis- and GR-mediated processes. Stress responses are common in lower vertebrates and could be the mediator between the environment (stressor) and gonadal sex differentiation in other forms of environmental sex determination besides TSD.