Bloodletting Acupuncture at Jing-Well Points Alleviates Myocardial Injury in Acute Altitude Hypoxic Rats by Activating HIF-1α/BNIP3 Signaling-Mediated Mitochondrial Autophagy and Decreasing Oxidative Stress

Objective: To explore the protective effect and possible mechanisms of bloodletting acupuncture at Jing-well points (BAJP) pre-treatment on acute hypobaric hypoxia (AHH)-induced myocardium injury rat. Methods: Seventy-five rats were randomly divided into 5 groups by a random number table: a control group (n =15), a model group (n =15), a BAJP group (n =15), a BAJP+3-methyladenine (3-MA) group (n =15), and a BANA (bloodletting at nonacupoint; tail bleeding, n =15) group. Except for the control group, the AHH rat model was established in the other groups, and the corresponding treatment methods were adopted. Enzyme-linked immunosorbent assay (ELISA) was used to detect creatine kinase isoenzyme MB (CK-MB) and cardiac troponins I (CTnI) levels in serum and superoxide dismutase (SOD) and malondialdehyde (MDA) levels in myocardial tissue. Hematoxylin-eosin (HE) staining was used to observe myocardial injury, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining was used to observe cell apoptosis. Transmission electron microscopy detection was used to observe mitochondrial damage and autophagosomes in the myocardium. The mitochondrial membrane potential of the myocardium was analyzed with the fluorescent dye JC-1. Mitochondrial respiratory chain complex (complex I, III, and IV) activities and ATPase in the myocardium were detected by mitochondrial respiratory chain complex assay kits. Western blot analysis was used to detect the autophagy index and hypoxia inducible factor-1 alpha (HIF-1 alpha)/Bcl-2 and adenovirus E1B 19k Da-interacting protein 3 (BNIP3) signaling. Results: BAJP reduced myocardial injury and inhibited myocardial cell apoptosis in AHH rats. BAJP pretreatment decreased MDA levels and increased SOD levels in AHH rats (all P < 0.01). Moreover, BAJP pretreatment increased the mitochondrial membrane potential (P < 0.01), mitochondrial respiratory chain complex (complexes I, III, and IV) activities (P < 0.01), and mitochondrial ATPase activity in AHH rats (P < 0.05). The results from electron microscopy demonstrated that BAJP pretreatment improved mitochondrial swelling and increased the autophagosome number in the myocardium of AHH rats. In addition, BAJP pretreatment activated the HIF-1 alpha/BNIP3 pathway and autophagy. Finally, the results of using 3-MA to inhibit autophagy in BAJP-treated AHH rats showed that suppression of autophagy attenuated the treatment effects of BAJP in AHH rats, further proving that autophagy constitutes a potential target for BAJP treatment of AHH. Conclusion: BAJP is an effective treatment for AHH-induced myocardial injury, and the mechanism might involve increasing HIF-1 alpha/BNIP3 signaling-mediated autophagy and decreasing oxidative stress.