Expression change of CREB1 in a mouse model of oxygen-induced retinopathy

Abstract

Objective To study the relationship between the expression of CREB1 and retinal neovascularization (RNV) in a mouse model of oxygen-induced retinopathy (OIR).Methods Postnatal day 7 (P7) mice (n=134) were randomly assigned to two groups:a control group (n=67) and an OIR group (n=67).OIR was induced by exposing P7 mice to (75±2)％ O2 for 5 days,followed by exposure to room air for an additional 5 days.P17 OIR mice were raised in the normal environment for additional 4 days.The mice from the control group were raised in a normal environment for 21 days.The P17 mice from the two groups were sacrificed,and retinal sections for HE staining and flat mounts after cardiac perfusion with FITC-dextran were used to detect RNV.Immunofluorescence of the frozen retinal sections showed the expression and location of the P-CREB1 protein.Real-time PCR and Western Blot were used to detect the expression of CREB1 in the retina.Two-way ANOVA was used for data comparison of the two groups at different time points and a Bonferroni post-test was used for comparison between two time points within a group.An independent samples t test at the same time points between the groups was used for statistical analysis.Results The number of cellular nuclei in the vascular endothelium breaking through the retinal internal limiting membrane was significantly higher in the OIR group than in the control group at P17 (t=11.31,P＜0.05).Areas of new retinal blood vessels and avascular zones were (21.40±2.72)％ and (30.61±3.12)％,respectively,in OIR mice at P17 P-CREB1 protein was expressed more strongly in the inner nuclear layer and ganglion cell layer of the retinas in the OIR group than in the control group.The results of real-time PCR and Western Blot showed that the relative expression levels of mRNA and CREB1 protein gradually increased from P7 to P17,followed by decreased expression at P21 in the control group.But the values were significantly higher in the OIR group than in the control group in mice of all ages except for P7 mice (P＜0.05).Conclusion These results indicate a space-time corresponding relationship between the expression of CREB1 and RNV.The overexpression of CREB1 could be involved in the process of RNV in the OIR model. Key words: CREB1 ; Oxygen-induced retinopathy ; Retinal neovascularization