Dual action of nitric oxide on purely isolated retinal ganglion cells

Purpose. The role of nitric oxide (NO) in the survival of retinal ganglion cells (RGCs) was investigated. Methods. RGCs were purely isolated from postnatal Sprague-Dawley rats by 2-step panning and were cultured in chemically defined serum free medium. An NO releaser, S-nitroso-N-acetylpenicillamine (SNAP: 500 muM, 250 muM, 100 muM, 10 muM, 1 muM, 100nM, and 10 nM), an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5tetramethylimidazoline-1-oxyl-3-oxide potassium salt (c-PTIO: 100 muM, 33 muM, 10 muM, 1 muM), mixture of 100 muM SNAP and 33 muM c-PTIO, N(G)-nitro-L-arginine methyl ester (L-NAME: 10 mM, 5mM, 500 muM, 100 muM or 10 muM), or their vehicles were added to the medium of pure RGC culture for 48 hr. Survival rates of small and large RGCs were determined separately by flow cytometry. Results. At 100 muM, SNAP significantly reduced RGC survival in a concentration dependent manner. At less than or equal to1 muM, SNAP significantly increased survival, particularly of large RGCs. c-PTIO and L-NAME reduced the survival rates concentration-dependently. A mixture of 100 muM SNAP and 33 muM c-PTIO significantly improved RGC survival compared with when they were added on their own. Conclusions. These results indicate that NO exhibits neuroprotective and neurotoxic actions on RGCs and that low concentrations of NO may be beneficial for the survival of neonatal RGCs in vitro.