SEASONAL VARIATION OF STEROID SYNTHESIS IN Rhinella arenarum FOLLICLES

ARIAS TORRES A.J; TRACANNA M.I.; BULACIOS G.A.; ZELARAYÁN L.I.

San Miguel de Tucumán

Jornada; XXX Jornadas Científicas: Asociación de Biología de Tucumán; 2013

Asociación de Biología de Tucumán

Although steroids have been considered the mediators of in vivo oocyte maturation, the physiological regulator of such process has not been determined yet. We decided to study the participation of the ovarian follicle in the seasonal steroids synthesis by TLC and its relationship with oocyte maturation. Complete follicles (fc) from ovaries of R. arenarum obtained in different seasons were incubated in Ringer solution (RA) in the presence or absence of hCG (10UI/mL) for 3, 6, 9 and 20 h. Steroids were extracted and analyzed by TLC. The fc remained in RA and at 24 h rupture of the germinal vesicle (RVG) was monitored. The results indicate that the winter fc incubated with hCG release P4 after 3 h of incubation, but only those fc incubated with hCG for 20 hours were able to mature (60% RVG). In the same period T levels were not detected by TLC. During the summer the stimulated follicles released testosterone (T) at all times analyzed, 35% of them matured at 6 h, 48% at 9 h and 100% ovulated in vitro at 20 h of incubation. Control fc did not mature (0% RVG) and steroids were not detected by TLC in either season. In the summer, T was the predominant steroid produced in the fc under gonadotropic stimulation. These results provide evidence of seasonal changes in ovarian steroidogenesis of R. arenarum in vitro.