Inhibiting MiR-34 reduces retinal cell apoptosis and downstream NF-B pathway in diabetic retinopathy rats through regulating HMGB1 expression

BACKGROUND: This is a research aimed to study the effect of micro ribonucleic acid (miR)-34a on the retinal cell apoptosis in diabetic retinopathy (DR) rats and its key molecular mechanism. METHODS: Sprague-Dawley rats were randomly divided into healthy group (H group, N.=5), diabetes group (D group, N.=5), diabetes + negative control transfection group (N group, N.=5) and diabetes + miR-34a inhibitor transfection group (M group, N.=5). The rat model of diabetes was established via intraperitoneal injection of 2% streptozotocin solution (60 mg/kg). After 72 h, the urine glucose and blood glucose were detected, and the urine glucose above 3+ and the blood glucose concentration >16.7 mmol/L indicated the successful modeling. After the rats were normally fed for 4 months, the changes in expression of miR-34 alpha in retinal tissues were detected via reverse transcription-polymerase chain reaction (RT-PCR), the pathological changes in retinal tissues were observed via hematoxylin-eosin (HE) staining, and the retinal cell apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Moreover, the changes in the number of cells containing active caspase-3 in retinal tissues were determined through immunohistochemistry, and the changes in expressions of caspase-3, high mobility group box 1 (HMGB1) and nuclear factor-kappa B (NF-kappa B) in retinal tissues were determined through Western blotting. RESULTS: Compared with those in H group, the cell density declined, and the cells were arranged disorderly with swelling in each retinal layer, the expression of miR-34 alpha in retinal tissues was increased, the retinal cell apoptosis was enhanced, the number of cells containing active caspase-3 in retinal tissues rose, and the expressions of caspase-3, HMGB1 and NF-kappa B in retinal tissues were increased in D group, N group and M group (P<0.05). Compared with those in D group and N group, the cell density rose, and the cells were arranged less disorderly with milder swelling in each retinal layer, the expression of miR-34 alpha in retinal tissues declined, the retinal cell apoptosis was weakened, the number of cells containing active caspase-3 in retinal tissues was decreased, and the expressions of caspase-3, HMGB1 and NF-kappa B in retinal tissues were reduced in M group (P<0.05). CONCLUSIONS: Inhibiting miR-34 alpha reduces the retinal cell apoptosis in DR rats through regulating the HMGB1 expression and downstream NF-kappa B pathway.