Inhibitory effects of 5-lipoxygenase on oxygen-induced retinal neovascularization in mice

Abstract

Objective To investigate the inhibitory effects of 5-lipoxygenase (5-LOX) on oxygeninduced retinal neovascularization in mice and to explore its possible mechanisms.Methods 7-day-old C57BL/6J mice were randomly divided into normal group,oxygen induced retinopathy (OIR) model group,large-dose group,small-dose group and control group with 12 mice in each group.The mice with their mothers were kept in (75±2)％ of oxygen environment for 5 days and then returned to normoxia for 5 days to establish the OIR model except for normal group.From postnatal day 12 to 17,the large-dose group and small-dose group received intravitreous injection of 5-LOX at dose of 100 mg/kg and 50 mg/kg respectively,while the control group received the same volume of 1 ％ dimethyl sulfoxide.The mice in the OIR group received no treatment.The number of endothelium cell nuclei breaking through the inner limiting membrane (ILM) was counted on hematoxylin and eosin-stained retinal section.The mRNA expression of 5 LOX,vascular endothelial growth factor (VEGF) a,VEGF receptor 2 (VEGFR-2) on retinal tissue were detected by reverse transcription polymerase chain reaction (RT-PCR).The protein expression of 5 LOX,VEGF a,VEGFR-2 and phosphorylation extracellular signal-regulated kinase (P-ERK) 1/2 on retinal tissue were detected by Western blot.Results The number of vascular cell nuclei breaking through the ILM in the large-dose group and small dose group decreased significantly compared with the OIR group and control group (F=73.390,P＜0.05).The mRNA expression and protein expression of 5-LOX,VEGFa,VEGFR 2 on retinal tissue were decreased significantly in the large-dose group and small dose group as compared with the OIR group and control group (F =92.668,P＜ 0.05).The difference of VEGFR-2 protein expression between large-dose group and small dose group was not significant (F=2.118,P＞0.05).The differences of 5-LOX,VEGF a,P-ERK 1/2 protein expression between large-dose group and small-dose group were significant (F=86.490,165.128,139.424; P＜0.05).Conclusion Hypoxia may induce 5 LOX expression in the retina.Retinal neovascularization was significantly inhibited by selective inhibition of 5 LOX. Key words: Retinal neovascularization/prevention & control; Arachidonate 5-lipoxygenase; Extracellular signal-regulated MAP kinases; Animal experimentation