MIRANDA Leandro Andres
Effects of light and temperature on GnRHs, GtHs expression and plasma steroids levels in Pejerrey (Odontesthes bonariensis) females
MIRANDA LA; STRUSSMANN CA; SOMOZA GM
FISH PHYSIOLOGY AND BIOCHEMISTRY
Lugar: Netherlands; Año: 2009 vol. 35 p. 101 - 101
In this study we examined the endocrine mediation between environmental factors (temperature and photoperiod) and the brainpituitarygonadal axis in females of pejerrey Odontesthes bonariensis. Changes in the expression of brain gonadotropin-releasing hormones (GnRHs) and gonadotropin (GtH) subunit [follicle stimulating-b (FSHb), luteinizing hormone-b (LH-b), glycoprotein hormone-a (GPH-a)] genes, plasma gonadal steroids [estradiol (E2) and testosterone (T)], gonadal histology, and gonadosomatic index (GSI) in adult females exposed to combinations of short-day (8 h) or longday (16 h) photoperiods and low (12C) or high (20C) temperatures after winter conditions (8 hlight, 12C) were analyzed. Pejerrey females kept under the short photoperiod had low GSIs, and their ovaries contained only previtellogenic oocytes regardless of the experimental temperature. In contrast, females exposed to the long photoperiod had high GSIs and ovaries with vitellogenic oocytes at both temperatures. These fish also showed a significantly higher expression of sGnRH, pjGnRH, cGnRH-II (the three different GnRH variants found to date in the pejerrey brain), FSH-b, LH-b and GPHa genes and plasma E2 levels than those at the shorter photoperiod. No significant changes were observed in plasma T levels. Based on these results, we concluded that the increase in day length but not that of temperature triggers the maturation of pejerrey females after the winter period of gonadal rest and that this occurs by an integrated stimulation of the various components of the brainpituitarygonad axis.