The Expression Of MiR210 And Stat3 In Rats Following Global Cerebral Ischemia And The Effect To Neuronal Apoptosis Though HIF-1α Signaling Pathway

Background and Objective Clinically, cardiac arrest, severe infections, intoxication, shock, anesthesia and low blood pressure conditions during surgery, comprehensive seizures and other critical disease can induce acute interruption of cerebral blood flow or low perfusion state, which results in insufficient supply of energy and oxygen in the brain. The brain tissue is vigorous metabolism, and its energy supply is mainly comes from aerobic metabolism of sugar, so, brain is sensitive to deficiency of blood flow and oxygen. Neurons irreversible damage will occur if the interruption of cerebral blood flow consists for 5 minutes. The activation of signaling pathway induced by insufficient of cerebral blood flow and energy following cerebral ischemia will mediate cell injury. This study is to detect the expression of MicroRNA210(MiR210) in cerebral cortex and the expression of signal transducer and activator of transcription3(stat3) in hippocampus following global ischemia in rats, and to explore the possible mechanism that the effect of MicroRNA210(MiR210) and Stat3 on neuron apoptosis though hypoxia inducible factor-1α(HIF-1α) signaling pathway.Methods The global cerebral ischemia model was induced by modified four-vessel occlusion method. Ninety adult SD rats(the model achievement ratio was 73% ) were randomly divided into three groups:Sham-operated group (n=6), global ischemia group (GI group, n=30), Stattic+global ischemia group(Stattic+ GI group, n=30). According to the point time after global ischemia reperfusion, rats in GI group and Stattic+GI group Stat3were randomly divided into six sub-groups:6h,12h,24h, 72h and 120h each subgroup has six rats and were killed by decapitation. Rats in sham-operated group were only subject to vertebral arteries electrocauterization, the carotid arteries were separated but not occluded, and the rats were killed by decapitation immediately after operation. All the rats in our research were about 250-280g. Rats in Stattic+ GI group were intraperitoneally injected Stattic solution (dissolved in 2%DMSO) after operation, and were given Stattic solution the same time every day during our research. However, rats in sham-operated group and GI group were given the same volume of 2%DMSO. Stat3, p-Stat3 and HIF-la protein expressions were detected by western blot analysis performed on hippocampus. MiR210, Stat3mRNA, HIF-la mRNA, VEGF mRNA and Caspse3mRNA were detected by real-time PCR analysis performed on cerebral cortex.Results 1.Western Blotting Analysis: ① ompared to sham-operated group, the expression of Stat3 in GI group was significantly increased since 6h after reperfusion (p<0.05)and was highest in 24h after reperfusion(p<0.01). The expression of p-Stat3 was significantly increased and peaked in 6h after reperfusion. ②ompared to GI group, the expression of Stat3 in Stattic+ GI group has no statistically change(P>0.05), but the expression of p-Stat3 was statistically decreased(P<0.05). ③ ompared to the sham-operated group, the expression of HIF-1α in GI group was increased since 6h after reperfusion(P<0.05), and peaked at 24h after reperfusion(P<0.01).④ Compared to GI group, the expression of HIF-1α in GI group was statistically decreased(P<0.05), and notably decreased at 24h after reperfusion(P<0.01).2. Real-time PCR analysis:①ompared to sham-operated group, the expression of MiR210 and Stat3 mRNA in GI group were significantly inereased(P<0.05) and peaked at 24h after reperfusion(P<0.01).②ompared to the sham-operated group, the expressions of HIF-1α mRNA、EGF mRNA and Capase3 mRNA in GI group were statistically increased(P<0.05).③Compared to GI group, the expression of HIF-1a mRNA in Stattic +GI group was statistically decreased since 12h after reperfusion(P<0.05),and notably decreased at 12h,24h and 72h after reperfusion(P<0.01); the expression of VEGF mRNA in Stattic+ GI group was significantly decreased at12h,24h,72h and 120h after reperfusion(P<0.05); the expression of Capase3 mRNA in Stattic+GI group was significantly decreased atl2h, 24h and 72h after reperfusion(P<0.05).Conclusion 1. The expressions of MiR210 and Stat3 were notably increased following global cerebral ischemia.2. A potential relationship may exist between the expression of MiR210 and HIF-la.3. The sever reduction of blood flow induced by global ischemia increased Stat3 activation and further augmented the expression of caspase3 mRNA, and one possible mechanism may be of the augmentative VEGF expression increased vascular permeability and induced neuronal edema, which may play though HIF-1α signaling pathway.