The temporal and spatial Norrin expression and significance in oxygen induced retinopathy

AIM: To detect the expression and location of Norrin in mouse retina with oxygen-induced retinopathy (OIR). METHODS: Retinal neovascular angiogenesis of OIR mouse was observed by FITC-Dextran filled retinamounts. Norrin, VEGF mRNA expression was studied by RT-PCR in control mouse retina on postnatal days 7, 10, 12, 17 and in OIR mouse retina on postnatal days 7, 8, 12, 12.5, 13, 14, 15, 17 and 19. Norrin protein expression and location was observed by immunohistochemical methods. RESULTS: Retinal neovasculature was observed in OIR ischemic mouse on postnatal days 17. Norrin mRNA expression markedly increased in retina after hypoxia 12 hours, which was correlated with the upregulation of VEGF. The peak of increase in Norrin occurred at 24 hours, and levels then decreased slowly. Norrin was expressed in outer layers of retina of P15-17 OIR mice, and was not found in normal control mice retina. CONCLUSION: Increased levels of Norrin in OIR ischemic retina show temporal correlation with increased expression of VEGF. Increased Norrin locates in outer layers of retina. Norrin may play an important role in neovascular angiogenesis.