The Study On Neuroprotective Effect And Mechanism Of Tetramethylpyrazine On Brain Injury In Mice Induced By Chronic Cerebral Hypoperfusion

Objective:This research establish animal models of chronic cerebral hypoperfusion by unilateral common carotid artery ligation,to observe the effect of tetramethylpyrazine on chronic hypoperfusion and to search for the mechanism of it,and to provide a theoretical and experimental basis for clinical application of tetramethylpyrazine for curing cerebral ischemia.Methods:Sixty healthy C57BL/6 male mice were randomly divided into four groups:sham operation group,model group,tetramethylpyrazine group,and positive drug group,15 mice in each group.Establish animal models of chronic cerebral hypoperfusion by unilateral common carotid artery ligation.The beam walking test was used to detect the mice’s exercise ability;The Morris water maze test was used to detect the cognitive function of mice;HE and Nissl body staining were used to observe the basic pathological changes of the neurons in the cortex and hippocampal CA1 regions;immunohistochemical method was used to detect the expression of HIF-1α,VEGF,and VEGFR-2 in the cortex area of mice.Result:1.Behavior test results of mice(1)The result of beam walking test showed that the number of sliding feet was increased,the incubation period became longer,and the complete walking time was prolonged in model group,compared with the sham operation group,and there was a statistically significant difference between the two groups(P<0.01).Compared with the model group,sliding feet was decreased(P<0.01),the incubation period and the total duration of the tetramethylpyrazine group mice was shortened,and there was a statistically significant difference between the two groups(P<0.05),indicating that the chronic cerebral hypoperfusion can cause the movement disorders in mice,and the mice’s ability of moving was improved by the treatment of tetramethylpyrazine.(2)The Morris water maze test results showed that the escape latency of the model group mice was significantly longer than that of the sham group,and the difference between the two groups was statistically significant(P<0.01),which indicated that the function has dropped significantly.Compared with the model group,the escape latency of the tetramethylpyrazine group was shortened,and the difference between the two groups was statistically significant(P<0.01),suggesting that the tetramethylpyrazine group can significantly improve the learning and memory ability of mice and improve the cognitive dysfunction.2.HE and Nissl staining results(1)The results of HE staining showed that the neurons in the cerebral cortex of sham-operated mice were well-arranged,with large cell bodies,and clear nucleoli.The neurons in the model group were disordered with many karyopyknosis.Compared with the model group,the absence of neurons and disordered arrangement of neurons in the tetramethylpyrazine group were all reduced.(2)Nissl staining showed that the Nissl bodies of neurons in the cortex were abundant in the sham-operated group,and the Nissl bodies of the neurons in the model group were significantly reduced(P<0.01).Compared with the model group,the Nissl bodies in neurons increased significantly in the tetramethylpyrazine group(P<0.01).3.Immunohistochemistry results showed that compared with sham group,the expression of HIF-1α,VEGF,VEGFR-2 protein in the model group increased significantly(P<0.01).Compared with the model group,the expression of HIF-la,VEGF,VEGFR-2 protein was significantly up-regulated in the tetramethylpyrazine group(P<0.01).Conclusion:1.Tetramethylpyrazine has the effect of improving motor dysfunction in mice with chronic cerebral hypoperfusion.2.Tetramethylpyrazine has the effect of improving cognitive impairment in mice chronic cerebral hypoperfusion.3.Tetramethylpyrazine can improve the brain morphology of mice with chronic cerebral hypoperfusion and reduce the nerve damage after ischemia.4.Tetramethylpyrazine can activate the HIF-la-VEGF-VEGFR-2 pathway,promote angiogenesis and improve blood flow in ischemic area protect neurons.In summary,tetramethylpyrazine up-regulate the expression of HIF-1α、VEGF、and VEGFR-2 proteins,activates the HIF-1α-VEGF-VEGFR-2 pathway,and improves the neuronal damage caused by ischemia,thereby improving the Learning and memory function in chronic cerebral hypoperfusion mice.