title: Cortisol-induced masculinization: does thermal stress affect gonadal fate in pejerrey, a teleost fish with temperature-dependent sex determination?
abstract: BACKGROUND
  Gonadal fate in many reptiles, fish, and amphibians is modulated by the temperature experienced during a critical period 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 unknown. We examined whether the stress-related hormone cortisol mediates between temperature and sex differentiation of pejerrey, a gonochoristic teleost fish with marked TSD, and the possibility that it involves glucocorticoid receptor- and/or steroid biosynthesis-modulation.
  
  
  RESULTS
  Larvae maintained during the period of gonadal sex differentiation at a masculinizing temperature (29 degrees C; 100% males) consistently had higher cortisol, 11-ketotestoterone (11-KT), and testosterone (T) titres than those at a feminizing temperature (17 degrees C; 100% females). Cortisol-treated animals 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 at a "sexually neutral" temperature (24 degrees C) caused significant increases in the proportion of males.
  
  
  CONCLUSIONS
  Our results suggest a role of cortisol in the masculinization of pejerrey and provide a possible link between stress and testicular differentiation in this gonochoristic TSD species. Cortisol role or roles during TSD of pejerrey seem(s) to involve both androgen biosynthesis- and GR-mediated processes. These findings and recent reports of cortisol effects on sex determination of sequential hermaphroditic fishes, TSD reptiles, and birds provide support to the notion that stress responses might be involved in various forms of environmental sex determination.
authors: Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors: Ricardo S
authors: RS
authors: Hattori
authors: Juan I
authors: JI
authors: Fernandino
authors: Ai
authors: A
authors: Kishii
authors: Hiroyuki
authors: H
authors: Kimura
authors: Tomomi
authors: T
authors: Kinno
authors: Miho
authors: M
authors: Oura
authors: Gustavo M
authors: GM
authors: Somoza
authors: Masashi
authors: M
authors: Yokota
authors: Carlos A
authors: CA
authors: Strüssmann
authors: Seiichi
authors: S
authors: Watanabe
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D005399:Fishes; D006854:Hydrocortisone / Q000032:analysis; D020287:In Situ Nick-End Labeling; D007814:Larva / Q000254:growth & development; D008297:Male; D012732:Sex Determination Analysis; D012733:Sex Differentiation / Q000187:drug effects*; D013696:Temperature; D013739:Testosterone / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D013739:Testosterone; D003907:Dexamethasone; C003600:11-ketotestosterone; D006854:Hydrocortisone