The protective effect of Ganoderma atrum polysaccharide against anoxia/reoxygenation injury in neonatal rat cardiomyocytes

Aims: Oxidative stress has been largely implicated in the pathogenesis of anoxia/reoxygenation injury. Ganoderma atrum polysaccharide (PSG-1), the most abundant component extracted from the fruiting bodies of G. atrum, has been shown to possess potent antioxidant activity. In this study, we investigated whether PSG-1 attenuates oxidative stress induced by anoxia/reoxygenation injury. Main methods: Primary cultures of neonatal rat cardiomyocytes pretreated with PSG-1 were exposed to anoxia/reoxygenation and subsequently monitored for cell viability by the MTT assay. Lactate dehydrogenase (LDH) release, manganese superoxide dismutase (MnSOD), catalase and glutathione peroxidase activities, and malondialdehyde contents were determined by a calorimetric method. The levels of reactive oxygen species (ROS) and apoptosis were determined by flow cytometry. Western blot analysis was used for the determination of MnSOD, catalase and glutathione peroxidase expression. Key findings: In the present study, PSG-1 protected the cardiomyocytes from anoxia/reoxygenation injury, as evidenced by decreased LDH release and increased cell viability in a dose-dependent manner up to 100 mu g/ml. This protective effect concomitantly decreased malondialdehyde contents, while significantly increased the activities and protein expressions of MnSOD, catalase and glutathione peroxidase. Furthermore, treatment with PSG-1 decreased ROS production and apoptosis in cardiomyocytes undergoing anoxia/reoxygenation. Significance: The present study first demonstrates that PSG-1 protects cardiomyocytes against oxidative stress induced by anoxia/reoxygenation by attenuating ROS production, apoptosis and increasing activities and protein expressions of endogenous antioxidant enzymes. (C) 2009 Elsevier Inc. All rights reserved.