Changes of NADPH oxidase expression in retina of rd mice / 中华实验眼科杂志

ABSTRACT

Background Studies showed that activation of microglia-derived nicotinamide adenine dinucleotide phosphate (NADPH) oxidase plays a key role in the neurodegenerative diseases and neural cell death in central nervous system.The effect of NADPH on cone degeneration have been determined in rd rats,its role in rod degeneration is relatively less studied.Objective This study was to study the expression of NADPH oxidase in the retinal degenerative process in rd mice and further explore its role in the photoreceptor degeneration.Methods rd Mice at postnatal day 8 (P8),P10,P12,P14,P16 and P18 were collected.The mice were sacrificed,and retinal sections,RNAs and proteins were prepared in above-mentioned time points.The expressions of the gp91 phox,a major subunit of NADPH oxidase,in transcript level and protein level in the retinas were semi-quantitatively detected by real-time PCR and Western blot respectively.Expression of gp91phox was localized in the rd retinas as ageing by immunohistochemstry,and the co-expression of gp91phox with CD11b,a specific marker of microglial cells,was assayed by immunofluorescent double labeling.The C57BL/6N mice were served as controls.The use and care of the animals complied with the Guideline of ARVO.Results Real-time PCR showed that gp91phox mRNA was not expressed in the retinas of C57BL/6N mice.Gp91phox mRNA was found to have less expressed in retinas of P8 rd mice.With aging,the expression level of gp91phox mRNA (gp91phox mRNA/β-actin) in rd mouse retinas was gradually increased with the highest level in P14 mice(1.136±0.370).A significant difference was seen in the gp91 phox mRNA expression among various groups of mice (F=17.81,P =0.00),and gp91phox mRNA expression was significantly elevated in P10,P12,P14,P16 and P18 rd mice compared with P8 rd mice(all at P＜0.05).The expression level of gp91phox protein (A value) in the retinas presented with a similar trend in the rd mice,with a significant difference among the various ages of rd mice and C57BL/6N mice (F =354.00,P＜0.01).The expression level of gp91 phox protein was increased in the rd mice in comparison with the C57BL/6N mice (all at P＜0.05).Immunochemistry revealed that the positive response cells for gp91phox increased in the inner layers of retinas in P10 rd mice and peaked in P14 mice.Immunofluorescent double labeling exhibited that gp91phox were seen to present a co-expression with CD11b,showing an orange fluorescence.Conclusions Expression of NADPH oxidase in the rctinas in the rd mice up-regulates and is parallels to the microglial activation and photoreceptor degeneration,suggesting that NADPH oxidase plays a role in the retinal dystrophy associated with microglial activation.