The Effect Of Hyperlipidemia On Expressions Of P38 And MMP-9 After Focal Cerebral Ischemia-reperfusion In Rats

Objective:To detect expressions of different reperfusion points of p38 and MMP-9 and observe the effect of hyperlipemia on expressions of p38 and MMP-9 following cerebral ischemia-reperfusion combined with hyperlipemia or simple cerebral ischemia-reperfusion.To test changes of expressions of p38 and MMP-9 after using p38 inhibitor SB203580,explore the interaction between p38 and MMP-9 during the process of cerebral ischemia reperfusion injury and study the mechanism which hyperlipemia aggravate cerebral ischemia reperfusion injury.Methods:120 SPF SD male rats were fed with high-fat diet, and 98 SD rats were fed with normal diet. Used Zea-longa suture method to establish the model of cerebral ischemia-reperfusion after establishing hyperlipidemia model. Rats were randomly divided into three groups: sham operated group, cerebral ischemia-reperfusion group and hyperlipemia with cerebral ischemia-reperfusion group. And each group was divided into six sub-groups, which were reperfusing 2h, 6h, 12 h, 24 h, 48 h and 72 h respectively. Then36 rats with hyperlipidemia were divided into four groups: sham+DMSO,sham+SB203580, I2R24+DMSO and I2R24+SB203580. Neuroethology score and TTC staining determine whether the model was successful or not. Detected the blood-brain barrier permeability by EB staining, observed the neuron morphology by Nissl staining,detected the expressions of p38 and MMP-9 by Immunohistochemistry and Western blotting, checked MMP-9 m RNA by RT-PCR.Results:Compared with sham group, the neurobehavioral scores increased in hyperlipemia with cerebral ischemia-reperfusion group and the simple cerebral ischemia-reperfusion group, P<0.05. Compared with the simple cerebral ischemia-reperfusion group, the neurobehavioral scores of hyperlipemia with cerebral ischemia-reperfusion group rose significantly, P<0.05. TTC staining showed that compared with the simple cerebral ischemia-reperfusion group, infarct volume expanded in the hyperlipemia with cerebral ischemia-reperfusion group, P<0.05. And the infarct volum peaked at reperfusion 24 h. EB staining showed: compared with sham group, the EB content in brain tissue of the hyperlipemia with cerebral ischemia-reperfusion group and the simple cerebral ischemia-reperfusion group rose obviously, P<0.05. EB content in brain tissue of hyperlipemia with cerebral ischemia-reperfusion group increased significantly than the simple cerebral ischemia-reperfusion group, P<0.05. EB content was the most at 24 h of reperfusion. Nissl staining showed that neuronal morphology of G+IR group and IR group changed. Their structure was loose and disordered. Nissl edge set and degraded. Detected the expression of p38 and MMP-9 by Immunohistochemistry and Western blotting, the expressions of p38 and MMP-9 began to increase at 2h of reperfusion. And the expressions of p38 and MMP-9 increased gradually with reperfusion time prolonged. The expressions peaked at reperfusion 24 h and gradually decreased later. Compared with cerebral ischemia-reperfusion group, the expressions of p38 and MMP-9 in hyperlipemia with cerebral ischemia-reperfusion group increased significantly at every reperfusion time point,P<0.05. Compared with DMSO group, the expressions of p38 and MMP-9 reduced significantly in SB group, P<0.05. The infarct volume, EB content in brain tissue and neurobehavioral scores reduced significantly than DMSO group, P<0.05.Conclusion:Hyperlipidemia aggravated cerebral ischemia-reperfusion injury by up-regulating p38 and MMP-9. The expressions of p38 and MMP-9 changed concordantly during the process of cerebral ischemia reperfusion injury. MMP-9 expression decreased after inhibiting p38 expression. p38 may indirectly regulate expression of MMP-9. They were involved in the destruction of the blood-brain barrier together.