Isosteviol attenuates myocardial ischemia-reperfusion damage by modulating Akt/GSK3β phosphorylation and mitochondrial permeability transition pore opening in female rats

Abstract

Presently, numerous studies are exploring the cardioprotective effects of compounds derived from native plants. In particular, research suggests that isosteviol may exert potential cardioprotective effects, linked to Protein Kinase B (Akt) activation. This study aimed to explore the role of Akt and GSK-3β in the cardioprotective effects mediated by the acute administration of isosteviol in Langendorff-perfused female rat hearts subjected to ischemia-reperfusion (Is-Rs). Hearts from female Wistar rats were subjected to Is-Rs. Isosteviol (5 µM) was added to the perfusate 10 min before ischemia. Wortmannin, a phosphatidylinositol 3-kinase (PI3K)/Akt inhibitor (100 nM), was added 15 min before ischemia. Mitochondrial ultrastructure was analyzed by electron microscopy, and the phosphorylation profile of Akt and GSK-3β were studied by western blot. Effects on mitochondrial permeability transition pore (MPTP) opening was assessed via calcium retention capacity (CRC). Docking studies using AutoDock4-Bias were performed to explore potential interactions between isosteviol and Akt or GSK-3β. ANOVA, n=6/group. Isosteviol improved cardiac post-ischemic mechanical recovery and reduced infarct size. It also increased the phosphorylation of Akt and GSK-3β after Is-Rs. Isosteviol treatment prevented MPTP opening, evidenced by the increase in CRC, and preserved mitochondria structure from the expected deterioration toward the end of Is-Rs protocol. All these beneficial effects were prevented, at least in part, by wortmannin. Finally, the results showed that isosteviol interacted with favorable binding energies at the phosphoinositide-binding site of Akt and the kinase site of GSK-3β. These results suggest that cardioprotective effects of isosteviol could be partly mediated by Akt activation, GSK-3β phosphorylation and the inhibition of MPTP opening.