Nitric oxide influences reactive oxygen species production and bovine oocyte in vitro maturation

SERGIO MORADO; PABLO CETICA; MARTHA BECONI; GABRIEL DALVIT

Huerta Grande (Argentina)

Congreso; I Reunión Conjunta de Sociedades de Biología de la República Argentina; 2007

Sociedad de Biología de Córdoba, Sociedad Argentina de Biología (SAB), Sociedad de Biología de Cuyo, Sociedad de Biología de Rosario, Sociedad de Biología de Tucumán

Nitric oxide (NO) produces inhibition of cytochrome oxidase and stimulation of O2- production by inhibition of electron transfer at complex III. The aim of this work was to determine NO participation in reactive oxygen species (ROS) production and meiotic maturation. Cumulus-oocyte complexes (COCs) were recovered from bovine ovaries and cultured in medium 199 (control), 0,5 mM N-nitro-L-arginine methyl ester (L-NAME, endothelial NO synthase inhibitor) and 10 M sodium nitroprusside (SNP, NO donor) at 39C, 5% CO2 in humidified air for 22h. A cytochrome oxidase inhibitor, 1 mM potassium cyanide was also assessed. Meiotic maturation was determined by the presence of metaphase II. ROS production was determined in denuded oocytes at 0, 6, 12, 18 and 22h by the ratio between 2?,7? dichlorodihydrofluorescein diacetate and fluorescein diacetate assays. Maturation percentages were 80, 81 and 58% for control, L-NAME and SNP, respectively. ROS levels fluctuated throughout the 22h of maturation, showing a similar pattern with the different treatments, but a decrease at 6h and an increase at 12h, were observed in COCs cultured in the presence of SNP compared to the control (p