Retinopathy of prematurity (ROP) causes blindness due to retinal vasculopathy caused by abnormal oxygen dynamics.Studies have clarified the pivotal role of vascular endothelial growth factor (VEGF) in the development of ROP, while the studies on the role of VEGF receptor (VEGFR) in ROP are fewer.

This study was to evaluate the relationship between the expressions of VEGFR-1 and VEGFR-2 in retina and post-birth time in the mice with oxygen-induced retinopathy (OIR).

Sixty 7-day-old (P7) SPF C57BL/6J mice together with lactating female mice were fed in the environment with (75±2)% oxygen concentration for 5 days and then returned to normal air to establish OIR models, and other 60 matched mice were kept in normal air environment as the control group.At P8, P11, P12, P13, P14, and P17, both eyes of each mouse were enucleated to prepare the retinal sections.Retinal blood vessels were examined by hematoxylin and eosin stain under the light microscope.Real-time fluorescence quantitative PCR and immunohistochemistry were used to detect the expressions of VEGFR1 mRNA and VEGFR2 mRNA and their proteins in mouse retinas, respectively.The use and care of the animals complied with the Regulations for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission.

Many vascular endothelial cell nucleus broke through the internal limiting membrane were seen with disorganized cell proliferation under the internal limiting membrane and retinal neovascularization bud in the P13, P14 and P18 mice in the OIR group, but no similar manifestation was found in the mice of the normal control group.The relative expression values of VEGFR-1 mRNA in retinas were significantly higher only in P12, P13, P14 and P18 mice in the OIR group than those in the normal control group (P=0.046, 0.000, 0.000, 0.042), but the expression values of VEGFR-2 mRNA were all increased in the retinas of P8, P11, P12, P13, P14 and P18 mice in the OIR group, showing significant differences in comparison with the normal control group (all at P=0.000).No considerable difference was found in the expression level of VEGFR-1 protein in P8, P11, P12, P13, P14 and P18 mice between the two groups (M=50.00, 36.00, 41.00, 31.00, 28.00, 36.00, all at P>0.05).The expression levels of VEGFR-2 protein in retinas of P8 and P11 were close between the two groups (all at P>0.05).Gradually attenuated expressions were seen in VEGFR-2 protein in P12, P13 mice of the normal control group, however, the expressions were enhanced in the OIR group, with significant differences between the two groups (all at P<0.01).Enhanced expressions of VEGFR-2 protein were found in P14 mice in both groups, but stronger expressions were in the OIR group (P<0.01).The positive response of the expression of VEGFR-2 protein was weaker in P18 mice in the normal control group but peaked in the OIR group, showing significant difference between them (M=20.11, P<0.01).

VEGFR participates in the neovascularization of OIR mouse, and the effect of VEGFR-2 is stronger than that of VEGFR-1 in the development of OIR neovascularization.

Retinopathy of prematurity; Oxygen-induced retinopathy; Vascular endothelial growth factor; Receptor; Real-time quantitative PCR; Immunohistochemistry; Mouse, C57BL/6J