Influence of miR-34a on cerebral neuronal apoptosis in rats with cerebral ischemia reperfusion through the Notch1 signaling pathway.

Abstract

To explore the influence and the underlying mechanism of micro-ribonucleic acid (miR)-34a on cerebral neuronal apoptosis in rats with cerebral ischemia-reperfusion (CIR). 60 adult male Wistar rats were randomly divided into 3 groups: Sham group, CIR group and miR-34a knockdown group. The rat model of CIR was established using the suture occlusion method. The expression level of miR-34a in lesion tissues in the three groups was determined via Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The pathological injury of brain tissues was detected via hematoxylin-eosin (HE) staining and the infarction region in each group was evaluated via triphenyl tetrazolium chloride (TTC) staining. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was performed to measure the cerebral neuronal apoptosis level. The level of Nissl's body in each group was detected via Nissl's staining. The expression level of the platelet-derived neurotrophic factor (PDNF) and Notch1/hypoxia-inducible factor-1α (HIF-1α) signaling pathway-related proteins in brain tissues were detected via immunohistochemistry and Western blotting, respectively. The expression level of miR-34a in brain tissues of the CIR group was significantly increased compared to that of the Sham group (p < 0.05). After the intervention with miR-34a, the infarction area of brain tissues was markedly reduced when comparing to the CIR group (p < 0.05). In addition, the results of HE staining and Nissl staining revealed that CIR treatment led to edema in cerebral neurons, disorderly arranged neurons, and remarkably decreased number of Nissl's bodies. However, miR-34a knockdown following CIR significantly alleviated the brain tissue injury and markedly increased the number of Nissl's bodies (p < 0.05). The results of TUNEL staining also indicated that miR-34a siRNA could remarkably reverse the cerebral neuronal apoptosis caused by CIR in rats (p < 0.05). According to the immunohistochemical staining results, the expression of PDNF in brain tissues declined in the CIR group, while enhanced in the miR-34a siRNA group (p < 0.05). Furthermore, the Western blotting results manifested that miR-34a siRNA could up-regulate the Notch1 and HIF-1α protein expressions in brain tissues of CIR rats. Our data demonstrated that the miR-34a knockdown could alleviate the brain tissue injury and neuronal apoptosis by activating the Notch1/HIF-1α signaling pathway CIR-treated rats.