[Effect of electroacupuncture on expression in blood-brain barrier in rats with cerebral ischemia-reperfusion injury by regulating HIF-1α/VEGF/MMP-9 signaling pathway].

Objectives: To observe the effect of electroacupuncture (EA) on the expression of hypoxia-inducible factor 1α (HIF-1α), vascular endothelial growth factor (VEGF), matrix metalloproteinases 9 (MMP-9) and tight junction proteins in rats with cerebral ischemia-reperfusion injury (CI/RI) , so as to explore its potential mechanism in alleviating injury of neurological function and blood-brain barrier (BBB).

Methods: A total of 84 male SD rats were used in the present study. The CIRI model was established by occlusion of the middle cerebral artery and reperfusion (MCAO/R), followed by dividing the CIRI rats into model group, EA group, and edaravone group (n=21 in each group). And another 21 normal rats were used as the sham operation group. For rats of the EA group, EA (2 Hz/15 Hz, 1 mA) was applied to "Baihui" (GV20) and "Zusanli" (ST36) on the affected limb for 20 min, once a day for 3 days. Rats of the edaravone group were intraperitoneally injected with edaravone injection (3 mg/kg), once a day for 3 days. The modified neurological severity score (mNSS) was used to evaluate the neurological behavior of rats. TTC staining was used to detect the percentage of cerebral infarction volume. HE staining was used to observe the pathological changes of cerebral cortex in ischemic area. Transmission electron microscopy was used to observe the changes of BBB ultrastructure in ischemic cortex. Evans blue (EB) staining was used to evaluate BBB permeability. Immunofluorescence was used to detect the expression of HIF-1α and VEGF protein in ischemic cortex. The protein and mRNA expressions of HIF-1α, VEGF, MMP-9, Zonula Occludens 1 (ZO-1), Occludin and Claudin-5 in the ischemic cortex were detected by Western blot or real-time PCR, respectively.

Results: Compared with the sham operation group, the neurological deficit score, the percentage of cerebral infarction volume, EB leakage, the positive expressions of HIF-1α and VEGF, the protein and mRNA expressions of HIF-1α, VEGF and MMP-9 of ischemic cortex were increased (P<0.01) in the model group , while the protein and mRNA expressions of ZO-1, Occludin and Claudin-5 were decreased (P<0.01). After the intervention and compared with the model group, the neurological deficit score, the percentage of cerebral infarction volume, EB leakage, the positive expressions of HIF-1α and VEGF, the protein and mRNA expressions of HIF-1α, VEGF and MMP-9 of ischemic cortex were decreased (P<0.01, P<0.05) in the EA and edaravone groups;the protein and mRNA expression of ZO-1, Occludin and Claudin-5 were increased (P<0.05, P<0.01) in the EA group;the protein and mRNA expression of Occludin were increased (P<0.01, P<0.05) and the mRNA expression of ZO-1 and Claudin-5 were increased (P<0.05, P<0.01) in the edaravone group. The ultrastructure of BBB was damaged in the model group, which were relatively milder in the EA and edaravone groups.

Conclusions: EA intervention can reduce BBB injury and improve neurological dysfunction in rats with cerebral ischemia-reperfusion, and the underlying mechanism may be related to the regulation of HIF-1α/VEGF/MMP-9 signaling pathway.