Activation of Nrf2 by Lithospermic Acid Ameliorates Myocardial Ischemia and Reperfusion Injury by Promoting Phosphorylation of AMP-Activated Protein Kinase α (AMPKα)

Abstract

Background: As a plant-derived polycyclic phenolic carboxylic acid isolated from Salvia miltiorrhiza, lithospermic acid (LA) has been identified as the pharmacological management for neuroprotection and hepatoprotection. However, the role and mechanism of lithospermic acid in the pathological process of myocardial ischemia-reperfusion injury are not fully revealed.Methods: C57BL/6 mice were subjected to myocardial ischemia and reperfusion (MI/R) surgery and pretreated by LA (50 mg/kg, oral gavage) for six consecutive days before operation. The in vitro model of hypoxia reoxygenation (HR) was induced by hypoxia for 24 h and reoxygenation for 6 h in H9C2 cells, which were subsequently administrated with lithospermic acid (100 μM). Nrf2 siRNA and dorsomorphin (DM), an inhibitor of AMPKα, were used to explore the function of AMPKα/Nrf2 in LA-mediated effects.Results: LA pretreatment attenuates infarct area and decreases levels of TnT and CK-MB in plasm following MI/R surgery in mice. Echocardiography and hemodynamics indicate that LA suppresses MI/R-induced cardiac dysfunction. Moreover, LA ameliorates oxidative stress and cardiomyocytes apoptosis following MI/R operation or HR in vivo and in vitro. In terms of mechanism, LA selectively activates eNOS, simultaneously increases nuclear translocation and phosphorylation of Nrf2 and promotes Nrf2/HO-1 pathway in vivo and in vitro, while cardioprotection of LA is abolished by pharmacological inhibitor of AMPK or Nrf2 siRNA in H9C2 cells.Conclusion: LA protects against MI/R-induced cardiac injury by promoting eNOS and Nrf2/HO-1 signaling via phosphorylation of AMPKα.

Cardiac fibroblast heat shock protein 47 aggravates cardiac fibrosis post myocardial ischemia–reperfusion injury by encouraging ubiquitin specific peptidase 10 dependent Smad4 deubiquitination

“…The mouse model of myocardial IRI was constructed as described 25 . Briefly, all rodents were anesthetized with pentobarbital serum (50 mg/kg, i.p.…”

“…After reperfusion for four weeks, rodents were anesthetized with 1.5% isoflurane inhalation to receive echocardiography monitoring, as previously described 25 . A MyLab 30CV system (Biosound Esaote, Inc.) equipped with a 15 MHz probe was used to monitor cardiac structure and function by a small animal ultrasound instrument.…”

“…A 1.4-French catheter tip micromanometer catheter (SPR-839; Millar Instruments, Houston, TX, USA) was used to obtain hemodynamic parameters, which was inserted into the left ventricle (LV) through the right carotid artery, as previously described 25 . Subsequently, ARIA pressure-volume (PV) conductance system (MPVS-300 signal conditioner, Millar Instruments, Houston, TX, USA) coupled with Power Lab/4SPA/D converter was used to measure PV parameters and display PV curve.…”

“…Histopathology analysis was performed as previously reported 25 . Briefly, heart tissues were fixed, embedded, and sectioned into 5 μm thick slices.…”

Activation of Nrf2 signaling: A key molecular mechanism of protection against cardiovascular diseases by natural products

“…DOX-induced cardiotoxicity was amplified in Nrf2 −/− mice, along with increased myocardial OS and cardiomyocyte necrosis (W. B. Zhang et al, 2021 ). Accumulating evidence over the last few years has demonstrated a critical role of the Nrf2/ARE signaling axis in preventing hyperglycemia-induced OS in diabetic heart ( Syed et al, 2021 ).…”