SEASONAL ANALYSIS OF STEROID-INDUCED MATURATION IN Rhinella arenarum OOCYTES

ARIAS AJ , ZELARAYÁN LI, BENITEZ L, BÜHLER MI

BIOCELL

INST HISTOL EMBRIOL-CONICET

Lugar: Mendoza; Año: 2012 vol. 35 p. 204 - 204

0327-9545

SEASONAL ANALYSIS OF STEROID-INDUCED MATURATION IN Rhinella arenarum OOCYTES Arias AJ1 , Zelarayán LI1, Benitez L2, Bühler MI1 1 Instituto de Biología-INSIBIO. Fac. de Bqca, Qca y Farmacia, UNT. Chacabuco 461. Tucumán lzelarayan@fbqf.unt.edu.ar 2 Fac. de Ciencias Naturales e IML. UNT. M. Lillo 205. Tucumán Amphibian ovarian oocytes do not usually resume meiosis unless stimulated with steroids. However, denuded Rhinella arenarum oocytes undergo spontaneous maturation when cultured in vitro without added hormones. The oocyte maturation has been best studied in Xenopus laevis, where androgens were the most potent promoters of this process and the most abundant steroid detected in the serum during ovulation. In this report we studied the seasonal role of testosterone (T) in Rhinella arenarum oocyte maturation comparatively with progesterone (P4) during three periods of the year: low (PB), high (PA) and high response whit spontaneous maturation (PAE). Follicles were harvested from Rhinella arenarum females during different periods: PB, PA and PAE. Totally grown follicles were selected and incubated for 20 hr with P4 or T (10-5- 10-8 M).  Meiosis resumption was scored by germinal vesicle breakdown (GVBD) after 20 hr of culture. Data were analyzed by ANOVA and Student’s t test. Our results showed that P4 and T were capable of promoting maturation in vitro in Rhinella arenarum oocytes in a doses dependent manner, but the biological response was higher with P4. The results of ANOVA were significant (p <0.05) for both hormones in all doses, but during PAE oocytes showed a great variability. The results of Student’s test (GVBD to each doses) the minimum response occur during PB to both hormones in all doses (p<0,01). No significant differences were found to P4 for all doses during PA and PAE. In conclusion, the present study suggests that in Rhinella arenarum, in a different manner to others amphibian, P4 has an important role than T during oocyte maturation.