The role of nitric oxide on apoptosis in human luteinized granulosa cells. Immunocytochemical evidence.

This study was designed to investigate the role of nitric oxide (NO) on the apoptosis of human luteinized granulosa cells and its possible pathways. Granulosa cell suspensions were incubated for 48 h after adding NO donor (S-nitroso-N-acetyl-penicillamine, SNAP) and NO synthase inhibitor (nitro-L-arginine methyl ester, L-NAME) at different concentrations. Apoptosis was examined using a terminal deoxynucleotide-transferase-mediated dUTP-biotin nick end labeling method in 70 patients, and immunocytochemical staining was performed for six apoptosis-related proteins in 50 patients. Apoptotic rates were significantly lower in cells incubated with 0.5 mM SNAP, but higher with 0.5, 1.0, and 5.0 mM L-NAME. SNAP (0.5 mM) lowered the expression of Fas and p53 in luteinized granulosa cells, but Bcl-2 expression was increased, and Fas ligand or Bax remained unchanged. Using L-NAME (0.5 and 5.0 mM), the expression of p53 and Bax was increased, but Bcl-2 was unchanged. Fas/Fas ligands were also activated especially in 5.0 mM L-NAME. In conclusion, NO may inhibit apoptosis via decreased Fas and p53, and increased Bcl-2 expression in human luteinized granulosa cells.