Electroacupuncture protects against cerebral ischemia-reperfusion injury through mitochondrial dynamics

Background: Electroacupuncture (EA) has been shown to promote functional recovery after cerebral ischemia-reperfusion (I/R) injury. However, the contribution of mitochondrial dynamics to recovery remains unclear. The aim of this study was to investigate whether mitochondrial dynamics are involved in the effects of EA on cerebral I/R injury. Methods: The rats with cerebral I/R injury were established by the middle cerebral artery occlusion/reperfusion. Subsequently, EA was applied to Baihui (GV20) and Dazhui (GV14) acupoints, with 2 Hz/5 Hz in frequency, 1.0 mA in intensity, 20 min each time, once a day for seven consecutive days. The therapeutic outcomes were assessed by modified neurological severity score (mNSS), 2,3,5-Triphenyte-trazolium chloride (TTC) staining, and hematoxylin-eosin (HE) staining. Mitochondrial morphology was observed under transmission electron microscopy. Adenosine triphosphate (ATP) content and ATP synthases (ATPases) activity were evaluated to measure mitochondrial function using ELISA. Finally, mitochondrial dynamics-related molecules, including dynamin-related protein 1 (Drp1), fission 1 (Fis1), mitofusin 1 (Mfn1), mitofusin 2 (Mfn2), and optic atrophy 1 (OPA1), were detected by Western blot and immunofluorescence staining. Results: Cerebral I/R injury induced neurological dysfunction, cerebral infarction and neuronal injury, all of which were ameliorated by EA. And EA improved mitochondrial morphology and function. Moreover, EA altered the balance of mitochondrial dynamics. Specifically, the data showed a significant decrease in the expression of Drp1 and Fis1, leading to the inhibition of mitochondrial fission. Additionally, Mfn1, Mfn2 and Opa1, which are related to mitochondrial fusion, were effectively promoted after EA treatment. However, sham EA did not show any neuroprotective effects in rats with cerebral I/R injury. Conclusions: In summary, our study indicates that the balance of mitochondrial dynamics is crucial for EA therapy to treat cerebral I/R injury.