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S-Adenosylmethionine modulates inducible nitric oxide synthase gene expression in rat liver and isolated hepatocytes

2001; Elsevier BV; Volume: 35; Issue: 6 Linguagem: Inglês

10.1016/s0168-8278(01)00208-2

1600-0641

Pedro Majano, Carmelo García‐Monzón, Elena R. García‐Trevijano, Fernando J. Corrales, Javier Cámara, P. Ortiz, José M. Mato, Matías A. Ávila, Ricardo Moreno‐Otero,

Biochemical effects in animals

Background/Aims: Hepatocellular availability of S-adenosylmethionine, the principal biological methyl donor, is compromised in situations of liver damage. S-Adenosylmethionine administration alleviates experimental liver injury and increases survival in cirrhotic patients. The mechanisms behind these beneficial effects of S-adenosylmethionine are not completely known. An inflammatory component is common to many of the pathological conditions in which S-adenosylmethionine grants protection to the liver. This notion led us to study the effect of S-adenosylmethionine administration on hepatic nitric oxide synthase-2 induction in response to bacterial lipopolysaccharide and proinflammatory cytokines. Methods: The effect of S-adenosylmethionine on nitric oxide synthase-2 expression was assessed in rats challenged with bacterial lipopolysaccharide and in isolated rat hepatocytes treated with proinflammatory cytokines. Interactions between S-adenosylmethionine and cytokines on nuclear factor kappa B activation and nitric oxide synthase-2 promoter transactivation were studied in isolated rat hepatocytes and HepG2 cells, respectively. Results: S-Adenosylmethionine attenuated the induction of nitric oxide synthase-2 in the liver of lipopolysaccharide-treated rats and in cytokine-treated hepatocytes. S-Adenosylmethionine accelerated the resynthesis of inhibitor kappa B alpha, blunted the activation of nuclear factor kappa B and reduced the transactivation of nitric oxide synthase-2 promoter. Conclusions: Our findings indicate that the hepatoprotective actions of S-adenosylmethionine may be mediated in part through the modulation of nitric oxide production.