RESUMEN
Effect of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on in vitro survival, growth, steroidogenesis, and apoptosis of buffalo preantral follicles (PFs) was investigated. PFs (200~250 microm) were isolated by micro-dissection and cultured in 0 (control), 10(-3), 10(-5), 10(-7), and 10(-9) M SNP. To examine the reversible effect of SNP, PFs were cultured with 10(-5) M SNP + 1 mM Nomega-nitro-L-arginine methyl ester (L-NAME) or 1.0 microg hemoglobin (Hb). The results showed that greater concentrations of SNP (10(-3), 10(-5), 10(-7) M) inhibited (p < 0.05) FSH-induced survival, growth, antrum formation, estradiol production, and oocyte apoptosis in a dose-dependent manner. However, a lower dose of SNP (10(-9) M) significantly stimulated (p < 0.05) the survival, growth, antrum formation, follicular oocyte maturation, and stimulated progesterone secretion compared to the control. A combination of SNP + L-NAME promoted the inhibitor effect of SNP while a SNP + Hb combination reversed this effect. Nitrate and nitrite concentrations in the culture medium increased (p < 0.05) in a dose-dependent manner according to SNP concentration in the culture medium. At higher concentrations, SNP had a cytotoxic effect leading to follicular oocyte apoptosis whereas lower concentrations have stimulatory effects. In conclusion, NO exerts a dual effect on its development of buffalo PFs depending on the concentration in the culture medium.