Melatonin but not vitamins C and E maintains glutathione homeostasis in t‐butyl hydroperoxide‐induced mitochondrial oxidative stress

• Published in: The FASEB journal 2000-09, Vol.14 (12), p.1677-1679
• Main Authors: Martín, Miguel, Macías, Manuel, Escames, Germaine, León, Josefa, Acuña-Castroviejo, Darío
• Format: Article
• Language: English
• Subjects: Animals; antioxidant; Antioxidants - pharmacology; Ascorbic Acid - pharmacology; Chromans - pharmacology; electron transport chain; free radicals; Glutathione - metabolism; Glutathione Disulfide - metabolism; Homeostasis - drug effects; Homeostasis - physiology; hydroperoxides; Melatonin - pharmacology; Mitochondria - drug effects; Mitochondria - physiology; mitochondrial oxidative damage; Oxidation-Reduction - drug effects; Oxidative Stress - drug effects; Oxidative Stress - physiology; Rats; tert-Butylhydroperoxide - pharmacology; Vitamin E - pharmacology
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fj.99-0865fje

Mitochondria do not contain catalase and are therefore largely dependent on reduced glutathione (GSH) and glutathione peroxidases for its antioxidant protection. When GSH levels are greatly decreased, hydrogen peroxide accumulates leading to extensive mitochondrial damage. Melatonin has antioxidant properties and prevents toxic effects of reactive oxygen species by maintaining cellular GSH homeostasis. Thus, we examined the influence of melatonin and other classical antioxidants such as vitamins C and E on GSH content and the activity of the GSH‐related enzymes (glutathione peroxidase and reductase) in isolated rat liver and brain mitochondria treated with t‐butyl hydroperoxide (i‐BHP). In control mitochondria melatonin (100 nM) significantly increases GSH content and glutathione peroxidase and reductase activities. After incubation with 100 μM i‐BHP, the mitochondrial hydroperoxides level increased, 90% of mitochondrial GSH was oxidized to GSSH, and the activities of GSH‐related enzymes were almost totally inhibited. Melatonin (100 nM) counteracted the changes in GSH, GSH‐related enzymes and hydroperoxides induced by i‐BHP in cultured mitochondria. In the presence of 100 nM melatonin, the activity of the respiratory chain complexes I and IV, measured in submitochondrial particles prepared from rat liver and brain mitochondria, increased significantly. Vitamin C was virtually without effect, and only 1 mM vitamin E increased GSH and reduced hydroperoxide mitochondrial contents. Our results suggest that melatonin, but not vitamins C and E, prevents the toxic effects of hydroperoxides on mitochondria by regenerating their GSH content.