Longxuetongluo Capsule alleviate ischemia/reperfusion induced cardiomyocyte apoptosis through modulating oxidative stress and mitochondrial dysfunction

Background: Chinese dragon's blood, the red resin of Dracaena cochinchinensis (Lour.) S. C. Chen., is widely used to treat cardiovascular and cerebrovascular diseases in China. Longxuetongluo Capsule (LTC) is a total phenolic compound extracted from Chinese dragon's blood, currently used in treating ischemic stroke. Myocardial injury can be aggravated after reperfusion of ischemic myocardium, which is called myocardial ischemia-reperfusion injury (MIRI), and the mechanism of MIRI is complex. However, the exact effect and mechanism of LTC on MIRI are still unclear. We explore the effect of LTC on alleviating MIRI based on mitochondrial dysfunction and oxidative stress. Aim of the study: To explore the cardioprotective mechanism of LTC against MIRI. Materials and methods: A rat MIRI model was constructed through ligation of the left anterior descending coronary artery, and LTC was given continuously for 28 days before surgery. The H9c2 cardiomyocyte injury model was induced by oxygen-glucose deprivation/reperfusion (OGD/R), and LTC was given 24 h before OGD. Myocardial ischemia areas were detected with 2,3,5-triphenyltetrazolium chloride (TTC) staining. Cardiac histopathological changes were detected with hematoxylin-eosin (HE) staining. And biochemical indexes were detected with serum biochemical kit. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) staining and flow cytometry were used to detect apoptosis. Fluorescent probes were used to observe reactive oxygen species (ROS), mitochondrial membrane potential (Delta Psi m), Ca(2+ )and other indexes. MitoTracker staining and immunofluorescence were used to observe the morphology of mitochondria and translocation of dynamin-related protein 1 (Drp1). Finally, immunohistochemistry and Western blotting were used to examine the expression of proteins related to apoptosis, mitochondrial fission and fusion and oxidative stress. Results: LTC could ameliorate cardiac pathological changes, decrease myocardial infarct area and the content or level of relevant serum cardiac enzymes, indicating that LTC could alleviate MIRI. Meanwhile, LTC could inhibit cardiomyocyte apoptosis via regulating apoptosis-related protein expression, and it could restore mitochondrial morphology, maintain Delta Psi m, inhibit mitochondrial ROS generation and Ca2+ accumulation, increase the expression of mitochondrial fusion protein 2 (Mfn2), decrease the level of phosphorylation dynamin-related protein 1 (p-Drp1), and regulate ATP synthesis, thereby significantly ameliorating mitochondrial dysfunction. Moreover, LTC significantly reduced the expression of NADPH oxidase 2 (NOX2), NADPH oxidase 4 (NOX4) and neutrophil cytosolic factor 2 (NOXA2/p67(phox)), and reduced ROS production. Conclusion: The study demonstrated that LTC could inhibit MIRI induced cardiomyocyte apoptosis by inhibiting ROS generation and mitochondrial dysfunction, and these fundings suggested that LTC can be used to alleviate MIRI, which provides a potential therapeutic approach for future treatment of MIRI.