Avaliação do efeito da metionina e/ou metionina sulfóxido sobre parâmetros de estresse oxidativo em fígado de ratos jovens: estudos in vitro e in vivo.

Abstract

There are several studies demonstrating that the methionine and/or its metabolites can be extremely toxic when found in high concentrations in tissues. Hypermethioninemic patients may have a varying degree of neurological dysfunction and liver abnormalities, whose mechanisms are not fully established. In the present study we investigated whether oxidative stress is elicited in vitro and in vivo by methionine (Met) and/or methionine sulfoxide (MetO) in liver of young rats. The effect of different concentrations of Met (20-2000 μM), MetO (5-500 μM), as well as Mixture (Mix) (1000 μM Met plus 500 μM MetO), and of acute administration of Met (0.4 g/Kg of body weight) and/or MetO (0.1 g/Kg of body weight) were studied on the following oxidative stress parameters: thiobarbituric acid reactive substances (TBARS), carbonyl content, total thiol content, catalase (CAT) and superoxide dismutase (SOD) activities. For in vivo studies, the animals were killed 1 h and 3 h after amino acids administration. In vitro studies showed that Met 1000 and 2000 μM, and Mix significantly increased CAT activity. The activity of SOD was enhanced by Met 1000 and 2000 μM, MetO 500 μM and Mix. In contrast, TBARS levels, carbonyl and thiol content were not altered by Met, MetO and association of these compounds. Acute administration showed that Met, MetO and Met plus MetO decreased TBARS at 1 h after injection. Total thiol content decreased at 1 h and increased at 3 h after MetO and Met plus MetO administrations. Carbonyl content was enhanced by Met and reduced by MetO at 1 h. Met, MetO and Met plus MetO decreased CAT activity at 1 h and 3 h after administration. Besides, only MetO increased SOD activity. Our findings indicate that Met and/or MetO alter redox cellular state in liver of young rats. It is assumed that these data can be associated, at least partly, with the liver damage observed in hypermethioninemic patients.