The Study Of Brain Protection Mechanism Of MiR-7 In A Deep Cryoablation Model In Mice

Part ? The expression of miRNAs in cerebral ischemia/reperfusion injury after deep hypothermic low flow of miceObjective To observe the change of 12 ischemia-related miRNAs in a model of mouse cerebral ischemia/reperfusion(I/R)injury after deep hypothermic low flow(DHLF).Methods The C57BL/6 mice(n=80)were randomly divided into DHLF model group and sham group.We adopted occlusion of bilateral common carotid artery in male C57BL/6 mice of 3 weeks old to establish the DHLF model.Then we examined miRNAs expression of brain tissue after 2h,6h,12 h and 24 h of occlusion by q RT-PCR.Student's t test was used for statistical evaluation.P<0.05 was considered statistically significant.Results Of the 12 miRNAs evaluated,9 showed upregulated expression and 2 showed downregulated expression at 1 out of 4 reperfusion time points studied between 2h and 24 h compared with control.Conclusion Expression of 11 miRNAs significantly changed in cerebral I/R injury after DHLF.It may played an important role in cerebral I/R injury after DHLF and provided a new strategy for the treatment of cerebral I/R injury after DHLF.Part ? The protective effect and mechanism of miR-7 on brain tissue undergoing deep hypothermic low flow model in mice.Objective To investigate the cerebral protective effect of miRNA-7 after undergoing deep hypothermic low flow ischemia reperfusion injury in mice and the related functional molecular mechanism.Methods The healthy male C57BL/6 mice(n=120)of 3 weeks old were randomly and equally divided into 3 groups:miR-7 agamir group,miR-7 antagomir group and control group,10 mice in each group.Respectively intracerebroventricular injection of miR-7 agomir,miR-7 antagomir and artificial cerebrospinal fluid,then established the DHLF model.Mice were sacrificed after 24 hours of ischemia reperfusion(I/R)and brain tissue was used to detect the expression of miR-7 by q RT-PCR.Longa grade and H.E.staining was to access the injury of nervous system and injury situation of hippocampus cells respectively.TUNEL assay was to detect apoptotic level of hippocampus cell.The expression of p-Akt,Akt,Bcl-2 and Bax was detected by Western blot analysis.Student's t test were used for statistical evaluation.Differences were considered statistically significant at P<0.05Results qRT-PCR revealed that miR-7 expression was upregulated after injected miR-7 agomir and was downregulated after injected miR-7 antagomir(p < 0.05).The result of Longa grade showed that nerve injury was lightist in miR-7 agomir group while was heaviest in miR-7 antagomir group(p < 0.05).H.E.staining results showed that the hippocampal cells damaged in miR-7 antagomir group,but it significantly eased in miR-7 agomir group.TUNEL assay showed that the hippocampal cell apoptosis was significantly increased in miR-7 antagomir group,on the contrary,it was significantly attenuated in miR-7 agonist group.Western blot revealed that miR-7 agomir upregulated the expression of p-Akt,Bcl-2 and downregulated Bax expression(p < 0.05).In contrast,miR-7 antagomir inhibited p-Akt and Bcl-2 expression,but increased Bax exression(p < 0.05).Conclusion miR-7 has neuroprotective effects in DHLF and its mechanism may be the miR-7 activated the PI3K/Akt signaling pathway to regulate the downstream key protein Bcl-2 and Bax.