1. Effects of nitric oxide in the simulated retinal ischemia induced by deprivation of glucose and oxygen

Purpose. To examine the neuroprotective effects of neuronal nitric oxide synthetase (NOS) inhibitor in the development of ischemic retinal degeneration. Methods. In the rat ex vivo retinal preparations, simulated ischemia was induced by deprivation of oxygen or glucose from the incubation medium. GYKI (non-NMDA receptor antagonist) were applied to the retinal samples in combination with 7-NIA (neuronal NOS inhibitor). The neuroprotective effects of these agents were evaluated by light microscopically and lactate dehydrogenase enzyme assay. Results. Oxygen deprivation induced axonal swelling of the retinal ganglion cells remaining other retinal layer intact. Deprivation of oxygen and glucose induced retinal excitotoxic damages. This neurodegeneration was prevented by the combination of GYKI and 7-NIA. Conclusions. The present study revealed that the neuronal NOS inhibitor seems to be partially neuroprotective against the ischemic retinal degeneration. Correspondence/Reprint request: Dr. Makoto Ishikawa, Department of Ophthalmology, Akita Graduate University Faculty of Medicine, 1-1-1 Hondo, Akita 010-8543, Japan E-mail: [email protected] ; [email protected] Makoto Ishikawa et al. 2