| ObjectiveTo confirm the neuroprotective effect of RIPC on chronic cerebral ischemia in rats by ligating bilateral common carotid artery permanently(permanent bilateral common carotid artery occlusion, BCAO) modified method.To make clear the protective mechanism of RIPC if have relationship with activation of Nrf2-ARE signaling Pathway or reduce phosphorylated tau protein level and Tau protein abnormal accumulation in neuronal.Methods(1)Adult SD rats were randomly divided into four groups: sham operation group(sham,n=20), permanent bilateral common carotid artery occlusion(BCAO,n=20),remote ischemic post-conditioning 3 day group(RIPC3d,n=20) and remote ischemic post-conditioning 4 week grouP(RIPC4w,n=20). The permanent node chronic cerebral ischemia rat model was established with modified by the method of bilateral common carotid artery, ligated one side of the common carotid artery and then the other side 3days later. RIPC was carried out immediately with rubber, ligated 10 minutes and relaxed 10 minutes( repeat 3 times, 2 times a day), Sham group only isolated vascular nerve, not for any other treatment.(2) The morris water maze test, the elevated plus maze test, and the object recognition test were used to test the ability of spatial learning and memory, anxiety,injury severity and neurological behavior in 4 weeks and 8 weeks.(3)After Neurobehavioral test, Nissl staining were used to observe the rat brain tissue morphological changes. Using Q-PCR to detect expression changes of Nrf2 and its downstream factors, such as SOD-2, HO-1, in rat brain tissue.The expression of protein of Nrf2 and SOD-2 was detected by Elisa, and the positive cells were locationed with immunohistochemistry and immunofluorescence.Results(1)RIPC can improve the cognitive decline caused by chronic cerebral ischemia in rats. The results show that the learning and memory of BCAO and RIPC weredecreased when compared with Sham group by the water maze test, there was a significant difference between the escape latency and the number of crossing platform(P<0.05). The BCAO group, the escape latency was significantly prolonged compared with RIPC3 d and RIPC4 w group(P<0.05), and the number of through the platform was significantly reduced(P<0.05); In 8 weeks of elevated plus maze and neurological scores, the number of open arm of the BCAO was significantly reduced compared with the Sham group(P<0.05), after the RIPC, the number of open arm was increased significantly(P<0.05). In the experiment of old and new object recognition, the rats of BCAO group’s explore behavior was significantly improved(P<0.05) compared with RIPC.(2)At the same time, the results of Q-PCR and Elisa showed that RIPC can up-regulate the expression of Nrf2, SOD-2, HO-1 and down-regulation TNFα and Tau Protein. The immunohistochemistry showed that Nrf2 and SOD-2 positive cells increased significantly in RIPC group, and Tau protein positive cells were decreasing.Nissl staining showed Nissl bodies decreased in BCAO when compared with the sham group, but increased in RIPC group.(3)Immunohistochemical results showed that, the number of positive cells of Nrf2 and SOD-2 in RIPC were significantly increased compared with the BCAO group,and the NeuN immunofluorescence results showed that the neurons in BCAO were damaged is more serious compared with the Sham group, positive cells were significantly increased in RIPC(P<0.05).Conclusion(1)RIPC have significant neuro protection for chronic cerebral ischemia rats,which can reduce neuronal injury and restrain the activation of endogenous oxidative stress. We also found that Tau protein may participate in the occurrence and development of chronic cerebral ischemia, and RIPC can reduce the abnormal accumulation of Tau protein.(2) RIPC is involved in the activation of Nrf2-ARE signaling pathway, raised its key factor Nrf2 and SOD-2 and down-regulation of tau protein and TNFα, activation ofendogenous oxidative stress, reduce non normal Tau accumulation, reduce neuronal injury and necrosis and protect the brain tissue. |
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