1,8-Cineole Alleviates Hypoxia-Reoxygenation-Induced Cardiomyocyte Injury by Activating AMPK/NLRP3 Signaling

Abstract

Background: Hypoxia/reoxygenation (H/R)-induced cardiomyocyte injury aggravates the progression of ischemic heart disease. The aim of this study was to explore the role of 1,8-Cineole on the H/R-induced cardiomyocytes injury. Methods: Cardiomyocytes (H9c2) were hypoxic for 6 hours (h) followed by 12 h reoxygenation to establish a cardiomyocyte injury model. After treatment with 1,8-Cineole (2.27 and 0.57 μmol/ L) or adenosine 5′-monophosphate activated protein kinase (AMPK) inhibitor (Compound C, 10 μmol/L), H9c2 cell viability, cytotoxicity, apoptosis and mitochondrial membrane potential (MMP) were examined by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT), lactate dehydrogenase (LDH) release detection assay, flow cytometry, and MMP assay kit with JC-1. Protein expression of caspase-3, cleaved caspase-3, B-cell lymphoma-2 (Bcl-2), Bcl-2 Associated X Protein (Bax), AMPK, phospho (p)-AMPK, NLR family pyrin domain containing 3 (NLRP3) and interleukin (IL)-1β were detected by Western blot. IL-1β level and caspase-1 activity were evaluated by commercial kit. Results: The results confirmed that 1,8-Cineole treatment enhanced viability and MMP. It decreased LDH levels and apoptosis in H9c2 cells under H/R induction (p < 0.05). Besides, H/R-triggered inhibition of Bcl-2 and p-AMPK protein expressions, as well as promotion of cleaved caspase-3, Bax, NLRP3 and IL-1β protein expression and caspase-1 activity in H9c2 cells were attenuated by 1,8-Cineole (p < 0.05). Compound C partially counteracted the effects of 1,8-Cineole on increasing cell viability, MMP and p-AMPK protein expression and decreasing LDH level, apoptosis and NLRP3 protein expression of H/R-induced H9c2 cells (p < 0.05). Conclusions: 1,8-Cineole protecting cardiomyocytes from H/R-induced cell injury is dependent on AMPK/NLRP3 signaling.