Dexmedetomidine attenuates H ₂O ₂-induced neonatal rat cardiomyocytes apoptosis through mitochondria- and ER-medicated oxidative stress pathways

Abstract

Dexmedetomidine (DEX), an α2 adrenoceptor agonist, has sedative and analgesic properties and myocardial protective effects. However, the mechanism underlying the protective effects of DEX on the myocardium remain unclear. The present study aimed to determine whether DEX serves an important role on cardioprotection through the endoplasmic reticulum (ER)- and mitochondria-mediated apoptosis signaling pathways. Neonatal rat cardiomyocytes (NRCMs) were cultured and divided four groups: i) Normal culture medium with 10% fetal bovine serum (control group); ii) H ₂O ₂ at 500 µM (H ₂O ₂ group); iii) DEX at 5 µM (DEX group); and iv) H ₂O ₂ plus DEX (H ₂O ₂ + DEX group). The levels of apoptosis and oxidative stress of NRCMs were investigated by ELISA, western blotting, flow cytometry and cell immunofluorescence. DEX significantly suppressed H ₂O ₂-induced apoptosis, and increased activity of caspases 3, 8 and 9 of NRCMs. DEX inhibited mitochondria-mediated oxidative stress and apoptosis, as evidenced by decreased levels of reactive oxygen species and lactic dehydrogenase, alleviated mitochondrial membrane potential depolarization, and increased Bcl-2-associated X protein/B-cell lymphoma 2 ratio. In addition, DEX decreased the activity of caspase 12, and the expression levels of glucose-regulated protein 78 kDa and serine/threonine-protein kinase/endoribonuclease IRE1, three major signaling molecules involved in the ER stress-mediated apoptosis pathway. Preventive treatment with DEX alleviates cardiomyocyte against H ₂O ₂-induced oxidative stress injury through attenuating the mitochondria- and ER-mediated apoptosis pathways.