Pretreatment with Notoginsenoside R1 attenuates high‐altitude hypoxia‐induced cardiac injury via activation of the ERK1/2‐P90RSK‐Bad signaling pathway in rats

Abstract

AbstractHigh‐altitude cardiac injury (HACI) is one of the common tissue injuries caused by high‐altitude hypoxia that may be life threatening. Notoginsenoside R1 (NG‐R1), a major saponin of Panax notoginseng, exerts anti‐oxidative, anti‐inflammatory, and anti‐apoptosis effects, protecting the myocardium from hypoxic injury. This study aimed to investigate the protective effect and molecular mechanism of NG‐R1 against HACI. We simulated a 6000 m environment for 48 h in a hypobaric chamber to create a HACI rat model. Rats were pretreated with NG‐R1 (50, 100 mg/kg) or dexamethasone (4 mg/kg) for 3 days and then placed in the chamber for 48 h. The effect of NG‐R1 was evaluated by changes in Electrocardiogram parameters, histopathology, cardiac biomarkers, oxidative stress and inflammatory indicators, key protein expression, and immunofluorescence. U0126 was used to verify whether the anti‐apoptotic effect of NG‐R1 was related to the activation of ERK pathway. Pretreatment with NG‐R1 can improve abnormal cardiac electrical conduction and alleviate high‐altitude‐induced tachycardia. Similar to dexamethasone, NG‐R1 can improve pathological damage, reduce the levels of cardiac injury biomarkers, oxidative stress, and inflammatory indicators, and down‐regulate the expression of hypoxia‐related proteins HIF‐1α and VEGF. In addition, NG‐R1 reduced cardiomyocyte apoptosis by down‐regulating the expression of apoptotic proteins Bax, cleaved caspase 3, cleaved caspase 9, and cleaved PARP1 and up‐regulating the expression of anti‐apoptotic protein Bcl‐2 through activating the ERK1/2‐P90RSK‐Bad pathway. In conclusion, NG‐R1 prevented HACI and suppressed apoptosis via activation of the ERK1/2‐P90RSK‐Bad pathway, indicating that NG‐R1 has therapeutic potential to treat HACI.