Age-related differences in glutathione metabolism in mussel tissues (Mytilus edulis L.)

Previous data indicate that in the digestive gland of marine mussels (Mytilus edulis L.) aging process is accompanied by increased oxidative stress conditions and reduction in the antioxidant defense systems and, among these, in the tissue levels of glutathione (GSH). Data are presented here on the tissue glutathione content and on the activity of the main enzymes involved in GSH metabolism (γ-glutamyl-cysteine synthetase, γ-glutamyl transpeptidase, GSSG reductase, GSH transferase) in the gills and digestive gland of mussels of three different age groups. The results indicate that the glutathione content was progressively decreased in both tissues of aging mussels. Similarly, aging seems to affect the activity of GSH-related enzymes and, in particular, the activity of γ-glutamyl cysteine synthetase, the enzyme that represents the rate-limiting step in GSH biosynthesis. These data indicate that, in aging mussels, the increased susceptibility to oxidative stress is partly related to alteration of glutathione metabolism. The results are discussed in the light of the current hypotheses on the aging process.