Mechanism Of Electroacupuncture Regulating MMP-9 In Protecting Blood-brain Barrier During Stroke Thrombolysis

Objective This study used the middle cerebral artery occlusion(MCAO)as model of cerebral ischemic stroke to explore whether electroacupuncture can reduce the elevation of MMP-9 caused by intravenous thrombolysis and further disruption of blood-brain barrier.We hope this study can provide a scientific basis for clinical application of acupuncture.Methods C57BL/6 mice were randomly divided into normal group,sham operation group,electroacupuncture group,thrombolytic group and model group.No treatment was given in normal group and sham operation group,and the latter three groups were intervened 2 hours after successful establishment of cerebral ischemic model.The nerve function scores were measured after 12 h of ischemia in each group to evaluate neurological damage.The area of cerebral infarction in normal group and model group was determined by TTC staining.The thrombolytic group was given rt-PA intravenous injection;the electroacupuncture group was given rt-PA intravenous injection and electroacupuncture treatment(Baihui,Fengfu acupoint).Magnetic resonance imaging was performed 12 hours later and using Radi Ant DICOM.Viewer(64-bit)software to calculate infarct volume.The Evans blue leak method was used to observe the blood-brain barrier permeability by measuring OD values;the dry-wet weighing method was used to determine the brain water content.Western blot was used to explore the expression of MMP-9 and LRP1 in mice brain.Results1.According to the Zea Longa score,the brain tissue of the normal group and the sham operation group had no ischemia,so there was no nerve damage or limb disability,and the scores were all 0.The scores of the thrombolytic group,the electroacupuncture group,and the model group were compared with the sham operation.There were statistical differences between the groups(P<0.05).Compared with the thrombolytic group,the scores of the electroacupuncture group were significantly lower,P <0.05.2.The volume of cerebral infarction was observed by MRI.The mice in the MCAO model were injected with rt-PA and the electroacupuncture group rt-PA+EA after2 hours.The results showed that there was obvious infarction in the thrombolytic group compared with the control group.P<0.05.Infarcts were reduced after electroacupuncture group intervention,P<0.05;there were statistical differences.It indicated that electroacupuncture intervention can reduce the infarct volume of mice with cerebral ischemia injury.3.The OD value was determined by Evans blue(EB)leakage method.There were a small amount of EB extravasation and cerebral edema in the model group,thrombolytic group,electroacupuncture group and brain.After electroacupuncture intervention,it effectively reduced EB extravasation and reduced brain edema(20% reduction in electroacupuncture group);normal group compared with thrombolysis group,P<0.05;thrombolysis group and electroacupuncture group,OD value decreased,P<0.05;there were statistical differences.4.The western blot method was used.Compared with the MCAO model group,the expression levels of MMP-9 and LRP1 protein increased significantly,P<0.05.After electroacupuncture intervention,the levels of MMP-9 and LRP1 in the electroacupuncture group were decreased compared with the electroacupuncture group,P<0.05;there were statistical differences.Conclusion1.Electroacupuncture Baihui and Fengfu points can protect the blood-brain barrier of cerebral ischemia mice treated with thrombolytic therapy and improve neurological deficit.2.The mechanism of electroacupuncture protecting blood-brain barrier,improving brain edema and reducing the degree of cerebral infarction may be achieved by inhibiting MMP-9 expression in the brain.