A pilot study on the relationship between miR-181a and RGCs in retinal ischemia-reperfusion injury model

Abstract

Background Retinal ischemia-reperfusion (RIR) injury is a common pathologic change.Its mechanism has not been identified. Objective This study was to investigate the relationship of microRNA-181a (miR-181a), tumor necrosis factor-α (TNF-α) and retinal ganglial cells (RGCs) in RIR injury. Methods RIR models were induced in 68 rats, then the rats were randomly divided into control group and RIR groups, including 0 hour group, 24-hour group and 72-hour group by random number table.Predicted target gene TNF-α was chosen, according to MiRanda, Targetscan and miRBase databases.Immunofluorescent labeling, Western blot and quantitative real-time PCR were used to identify the expression levels of miR-181a, TNF-α and RGCs.Immunofluorescent labeling of RGCs in retinal flat mounts was analyzed for RGCs counts. Results Compared with the control group, RGCs densitiy was obviously decreased in 24-hour and 72-hour RIR groups (P<0.001). The expression level of mir-181a significantly decreased with reperfusion time in the RIR groups (P<0.05). Futhermore, the expression level of miR-181a was positively correlated with RGCs numbers (r=0.995, P=0.005). TNF-α and miR-181a were mainly located in inner layers of retina.As opposed to the changes in RGCs numbers and miR-181a expression, TNF-α in 24-hour group was obviously higher than that of the 0-hour group, though there was no statistical significance in overall correlation analysis. Conclusions In RIR, miR-181a may be involved in regulating RGCs apoptosis.TNF-α may be a target gene of miR-181a.Interventions within 24 hours after reperfusion might be critical.Further study of miR-181a may help to explore new molecular targets for neuroprotection treatment. Key words: Retinal ischemia-reperfusion; Retinal ganglion cells; Tumor necrosis factor-α; microRNA-181a