Aerobic interval training preconditioning protocols inhibit isoproterenol-induced pathological cardiac remodeling in rats:Implications on oxidative balance,autophagy,and apoptosis

This study aimed to investigate the potential cardioprotective effects of moderate and high-intensity aerobic interval training(MIIT and HIIT)preconditioning.The focus was on histological changes,pro-oxidant-antioxidant balance,autophagy initiation,and apoptosis in myocardial tissue incited by isoproterenol-induced pathological cardiac remodeling(ISO-induced PCR).Male Wistar rats were randomly divided into control(n=6),ISO(n=8),MIIT(n=4),HIIT(n=4),MIIT+ISO(n=8),and HIIT+ISO(n=8)groups.The MIIT and HIIT protocols were administered for 10 weeks,followed by the induction of cardiac remodeling using subcutaneous injection of ISO(100 mg/kg for two consecutive days).Alterations in heart rate(HR),mean arterial pressure(MAP),rate pressure product(RPP),myocardial oxygen consumption(MVO_(2)),cardiac hypertrophy,histopathological changes,prooxidant-antioxidant balance,autophagy biomarkers(Beclin-1,Atg7,p62,LC3Ⅰ/Ⅱ),and apoptotic cell distribution were measured.The findings revealed that the MIIT+ISO and HIIT+ISO groups demonstrated diminished myocardial damage,hemorrhage,immune cell infiltration,edema,necrosis,and apoptosis compared to ISO induced rats.MIIT and HIIT preconditioning mitigated HR,enhanced MAP,and preserved MVO_(2)and RPP.The pro-oxidant-antioxidant balance was sustained in both MIIT+ISO and HIIT+ISO groups,with MIIT primarily inhibiting pro-apoptotic autophagy progression through maintaining pro-oxidant-antioxidant balance,and HIIT promoting pro-survival autophagy.The results demonstrated the beneficial effects of both MIIT and HIIT as AITs preconditioning in ameliorating ISO-induced PCR by improving exercise capacity,hemodynamic parameters,and histopathological changes.Some of these protective effects can be attributed to the modulation of cardiac apoptosis,autophagy,and oxidative stress.