Nitric oxide, microglial activities and neuronal cell death in the lateralgeniculate nucleus of glaucomatous rats

The present study was initiated to investigate neuronal degeneration, micro glial reactivity and possible roles of NO in the lateral geniculate nucleus (LGN) of glaucomatous rats. An experimental one-eye glaucoma model was cre ated by cauterization of the limbal-derived veins. Neuronal cell viability was studied by immunostaining with antibody against neuronal nuclei. Change s of expressions of nitric oxide synthase I (NOS I), NOS II, ED 1, OX6 and OX42 in the LGN were studied by immunohistochemistry. NADPH-d histochemistr y was also employed. In the experimental glaucomatous rats, the number of N euN labelled neurons was significantly decreased in both the ipsi- and cont ra-lateral sides of the ventral LGN (vLGN) but not the dorsal LGN (dLGN) at 1 month post-operation and beyond. Expressions of NOS I and NADPH-d were n otably increased from 1 week post-operation in the ipsilateral vLGN. In the contralateral side of the vLGN. however, this change was only observed fro m 1 month post-operation. No NOS II immunoreaction was observed in LGN of b oth the normal control and glaucomatous rats. Increased microglial reactivi ty as indicated by OX-42 immunoreactivity was first observed in both sides of the LGN at 1 week post-operation, and this was most significant especial ly at 1 and 2 months post-operation. The present results suggest that NO an d microglial cells may play some important roles in the pathologic processe s of neuronal degeneration in the LGN of glaucomatous rats. (C) 2000 Elsevi er Science B.V. All rights reserved.