Tumor necrosis factor-alpha (TNF-alpha) is implicated in heart failure and cardiomyocytes themselves can express TNF-alpha. Nevertheless, the mechanisms and regulations of TNF-alpha expression in cardiomyocytes remain poorly understood. The present study was to investigate the effects of simvastatin on TNF-alpha expression in cardiomyocytes and the underlying molecular mechanisms. In neonatal rat cardiomyocytes, RT-PCR and ELISA showed lipopolysaccharide (LPS)-induced TNF-alpha expression was attenuated by sinivastatin pretreatment in a dose-dependent manner. The reactive oxygen species (ROS) scavenger N-acetyleysteine and the NADPH oxidase inhibitor diphenyleneiodonium also inhibited the LPS-induced expression of TNF-alpha. Dichlorofluorescein-fluorescence and cytochrome c reduction assay indicated LPS increased ROS generation and NADPH oxidase activity in cardiomyocytes, which were abrogated by sinivastatin. Furthermore, similar to LPS, exogenous hydrogen peroxide also increased TNF-alpha secretion, but sinivastatin did not significantly affect the hydrogen peroxide-induced TNF-alpha secretion. All the effects of simvastatin as mentioned above were completely reversed by concomitant pretreatment with mevalonate, a key intermediate during cholesterol synthesis. These results suggest that sinivastatin attenuates LPS-induced TNF-alpha expression in cardiomyocytes via inhibition of activation of NADPH oxidase and subsequent ROS generation. (c) 2006 Elsevier Inc. All rights reserved.