The purpose of this study is to evaluate the changes in neurofilament light (
NF-L) protein in the optic nerve in rat
kainate and monkey
ocular hypertension models. In the rat model, optic nerve damage was induced by
kainate injection into the vitreous body. In the monkey model,
photocoagulation of the trabecular meshwork led to
laser-induced
ocular hypertension. NF-L in optic nerve extract was quantified by quantitative immunoblot using an imaging analyzer. The amount of NF-L in optic nerve was compared between normal and
kainate-treated groups at 7 days after
kainate injection. Specimens from rat optic nerves and retinas were evaluated histologically to examine the correlations between damage and amount of NF-L in the optic nerve. In monkeys, the amount of NF-L in the optic nerve was compared between control fellow and ocular hypertensive eyes. Injection of
kainate induced morphological optic nerve and
retinal damage in rats. The amount of NF-L in the optic nerve was significantly reduced in
kainate-treated eyes (vs. normal eyes). The amount of NF-L correlated with the cell count in the
ganglion cell layer and the axon number in the optic nerve at 7 days after
kainate injection. Further, 6-cyano-7-nitro-quinoxaline-2,3-dione, a non
N-methyl-D-aspartate receptor antagonist, suppressed the
kainate-induced reduction in NF-L and
retinal damage. In the monkey model,
ocular hypertension and morphological optic nerve damage were shown by
laser-treated eyes. The amount of NF-L in the optic nerve was reduced in
laser-treated eyes. In conclusion, in rat
kainate and monkey
ocular hypertension models, immunoblot evaluation of NF-L shows the reduction of the amount of NF-L in the optic nerves of treated-eyes. The amount of NF-L correlated with the morphological
retinal and optic nerve damage in rats. These findings indicate that immunoblot evaluation of NF-L in the optic nerve may provide a quantitative index of optic nerve damage.