Cardioprotective Effect of Stem-Leaf Saponins From Panax notoginseng on Mice With Sleep Deprivation by Inhibiting Abnormal Autophagy Through PI3K/Akt/mTOR Pathway

Abstract

Sleep deprivation (SD) may lead to serious myocardial injury in cardiovascular diseases. Saponins extracted from the roots of Panax notoginseng, a traditional Chinese medicine beneficial to blood circulation and hemostasis, are the main bioactive components exerting cardiovascular protection in the treatment of heart disorders, such as arrhythmia, ischemia and reperfusion injury, and cardiac hypertrophy. This study aimed to explore the protective effect of stem-leaf saponins from Panax notoginseng (SLSP) on myocardial injury in SD mice. SD was induced by a modified multi-platform method. Cardiac morphological changes were assessed by hematoxylin and eosin (H&E) staining. Heart rate and ejection fraction were detected by specific instruments. Serum levels of atrial natriuretic peptide (ANP) and lactate dehydrogenase (LDH) were measured with biochemical kits. Transmission electron microscopy (TEM), immunofluorescent, and Western blotting analysis were used to observe the process and pathway of autophagy and apoptosis in heart tissue of SD mice. In vitro, rat H9c2 cells pretreated with rapamycin and the effect of SLSP were explored by acridine orange staining, transient transfection, flow cytometry, and Western blotting analysis. SLSP prevented myocardial injury, such as morphological damage, accumulation of autophagosomes in heart tissue, abnormal high heart rate, serum ANP, and serum LDH induced by SD. In addition, it reversed the expressions of proteins involved in the autophagy and apoptosis and activated PI3K/Akt/mTOR signaling pathway that is disturbed by SD. On H9c2 cells induced by rapamycin, SLSP could markedly resume the abnormal autophagy and apoptosis. Collectively, SLSP attenuated excessive autophagy and apoptosis in myocardial cells in heart tissue induced by SD, which might be acted through activating PI3K/Akt/mTOR signaling pathway.