DNA damage and repair in the visual center in the rhesus monkey model of glaucoma

Abstract

To study the DNA damage and repair methods of visual central neurons in a glaucoma model, a rhesus monkey chronic glaucoma model was established by laser induction, and changes in intraocular pressure (IOP), the optic cup fundus, the thickness of the retinal nerve fiber layer and the diameter of the optic nerve were evaluated. After a sufficient period of time, the model was euthanized, and the lateral geniculate body, primary visual cortex (V1 region) and secondary visual cortex (V2 region) were removed. Through immunofluorescence, ELISA and western blotting assays, the expressions of 8-hydroxyguanosine (8-OHG), a biomarker of oxidative stress, and γH2AX, a marker of DNA double-strand breaks, in the neurons of the LGN, V1 and V2 in the glaucoma model were higher than those of the control group (P < 0.05). The expression of key DNA repair proteins Ku80, Mre11, PCNA, DNA ligase IV and APE1 antibodies in the LGN, V1 and V2 of the glaucoma model was higher than that of the control group (P < 0.05), and in the positive TUNEL cells, the levels of cleaved caspase 3, Beclin 1 and LC3B-II/LC3B-I were significantly increased in the LGN of the glaucoma model (P < 0.05), but there was no significant positive expression in the V1 and V2 regions of the glaucoma model compared with the normal control group (P > 0.05). Transmission electron microscopy also showed that apoptotic bodies and autolysosomes (changes in neuronal apoptosis and autophagy activation) appeared in some neurons of the LGN in glaucoma, but there were no significant abnormal changes in the V1 and V2 regions of glaucoma or in any specimens in the normal group. In terms of neuron counting, the number of neurons in the LGN of the glaucoma model was lower than that in the normal control group (P < 0.05), but there was no significant difference in the number of neurons in the V1 and V2 regions between the two groups (P > 0.05). Similarly, the expression of glial cells in the LGN, V1 and V2 of the glaucoma model was higher than that in the control group (P < 0.05). Therefore, the results showed that DNA oxidative damage and various repair processes occurred in neurons of the LGN, V1 and V2 of the glaucoma model, and finally, LGN neurons died in the glaucoma model.

Keywords: Apoptosis; Autophagy; DNA damage; Glaucoma; Lateral geniculate nucleus; Visual cortex.