Eye acupuncture improves cerebral ischemia reperfusion injury by improving autophagy via ATF6 pathway in cerebral ischemia reperfusion injury rats

Abstract

To explore the effect of eye acupuncture on autophagy and expressions of autophagy-related proteins Beclin1, LC3B, ATF6 and XBP1 in the infarction area of brain tissue in rats with acute cerebral ischemia-reperfusion injury (CIRI), so as to explore its mechanisms underlying improvement of CIRI. Male SD rats were randomly divided into sham operation, model and eye acupuncture groups (n=16 in each group). The CIRI model was prepared by occlusion of the middle cerebral artery. Eye acupuncture stimulation was applied to bilateral "Gan"(Liver), "Shangjiao"(Upper-energizer), "Xiajiao"(Lower-energizer) and "Shen"(Kidney) regions at 0, 12 and 24 h after CIRI, 30 min each time. The neurological deficit score was given by referring to Longa's method, and TTC staining used to determine the success of model replication. After the treatment, the pathological changes of the cerebral infarction area were observed under light microscope, and the autophagosomes were observed by electron microscope. The protein expression levels of LC3B, Beclin1, ATF6 and XBP1 in the infarction area of brain tissue were detected by Western blot. The immunoactivity of Beclin1 and the immunofluorescence density of ATF6 and XBP1 in the infarction area of brain tissue were determined by immunohistochemistry. The Longa's score, and the protein expression levels of LC3B, Beclin1, ATF6 and XBP1 and immunoactivity or immunofluorescence density of Beclin1, ATF6 and XBP1 were significantly higher in the model group than those in the sham operation group (P<0.01), and considerably lower in the eye acupuncture group than those in the model group (P<0.01). Under light microscope, the model group had typical ethmoidal reticular cerebral infarction, while the eye acupuncture group had significantly smaller areas and clearer edges. Under electron microscope, there were more autophagosomes in the cytoplasm of neurons in the model group, and fewer autophagosomes in the eye acupuncture group (in contrast to the model group). Eye acupuncture can improve the neurological function and mitigate cerebral injury in CIRI rats which may be associated with its function in inhibiting autophagy in the brain tissue by regulating ATF6 pathway.