Electroacupuncture reverses endothelial cell death and promotes angiogenesis through the VEGF/Notch signaling pathway after focal cerebral ischemia-reperfusion injury

Abstract

Background: Angiogenesis is an important mechanism of recovery from ischemic stroke. Recent studies have found that there is a close relationship between the VEGF/Notch pathway and angiogenesis. It is unknown whether EA can exert a brain protection effect and promote angiogenesis by acting on the VEGF/Notch signaling pathway after focal cerebral ischemia-reperfusion injury (CIRI).

Methods: The Middle Cerebral Artery occlusion/Reperfusion (MCAo/R) model was established, in which rats were subjected to occlusion with ischemic intervention for 30 min, followed by reperfusion for 8 h, 1 day, 3 days, and 7 days. The first EA treatment was performed 90 min after the animal model was successfully established, and then EA treatments were performed once a day for 7 days. The 2,3,5-triphenyltetrazolium chloride staining and neurological deficit examination were performed to assess the level of CIRI and neuroprotection by EA. Expression levels of VEGFA, Notch1, and Hes1 proteins were measured via western blotting, while the morphological changes of ECs and microvasculature in the cortex were determined using an ultrastructural observation method.

Results: EA treatment of PC6, GV26, and SP6 can significantly improve the neurological function of MCAO/R rats, reduce the volume of cerebral infarction, and modulate the ultrastructure of ECs and microvessels in pathological states. Western blotting revealed that EA increased VEGFA protein expression at 8 h and 3 days after CIRI, as well as Notch1 protein expression at 1 and 7 days. Subsequently, EA activated the VEGF/Notch pathway, increasing the expression of the downstream target protein Hes1, reversing EC death, and promoting angiogenesis.

Conclusion: Our findings showed that EA plays a role in promoting angiogenesis following focal CIRI, and we hypothesized that this was due to the regulation of ECs by the EA-activated VEGF/Notch signaling pathway.

Keywords: VEGF/Notch signaling; angiogenesis; cerebral ischemia-reperfusion injury (CIRI); electroacupuncture (EA); endothelial cells (ECS).