Electroacupuncture Pretreatment at Neiguan (PC6) attenuates autophagy in rats with myocardial ischemia reperfusion through the phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin pathway.

Abstract

OBJECTIVE\nTo investigate the protective efficacy of electroacupuncture (EA) pretreatment at Neiguan (PC6) on myocardial ischemia-reperfusion (I/R) in rats.\n\n\nMETHODS\nFifty rats were randomly divided into five groups (n = 10): sham operation group, model group (underwent in vivo myocardial I/R), EA pretreatment group [EA at Neiguan (PC 6) 1 week before I/R], wortmannin group (1 week before I/R, the PI3K inhibitor, wortmannin, was injected), EA pretreatment + wortmannin group (both pretreatments were performed simultaneously). After establishing the I/R model, 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to analyze the weight and area of the myocardial infarction tissue. The biosignal and pressure test system was used to determine the left ventricular systolic mean pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), fractional shortening (FS), and ejection fraction (EF). Ultraviolet spectrophotometry was used to determine the expression of creatine kinase (CK)-MB, inducible nitric oxide synthase (iNOS), and total antioxidant capacity (T-AOC) in the serum. The expression of autophagy-related protein 13 (ATG13), mammalian target of rapamycin (mTOR), and phosphatidylinositol 3-kinase (PI3K) in cardiac muscle cells was determined by immunofluorescence. Hematoxylin and eosin staining was used to observe autophagy-related pathological changes in rat cardiomyocytes, and ultrastructural changes of cardiomyocytes were examined by transmission electron microscopy.\n\n\nRESULTS\nIn this study, the infarction size and tissue weight of the EA pretreatment group were decreased compared with the model group (P < 0.0001). Furthermore, compared with the model group, the LVEDP values of the EA pretreatment group were significantly reduced (P = 0.0091), and the LVSP, FS, and EF values were slightly increased (P = 0.0007, 0.0020, 0.0031). EA pretreatment also significantly decreased the expression of CK-MB and iNOS, while it increased the expression of T-AOC in the serum of rats with I/R injury (P < 0.0001). Furthermore, EA pretreatment slightly widened the myocardial fiber space, reduced necrosis and myocardial cell swelling and maintained the nucleus and mitochondria structure intact.\n\n\nCONCLUSION\nEA pretreatment promoted autophagy flux and alleviated myocardial I/R injury through the PI3K-Akt-mTOR pathway.