The Immunohistochemical Localization of Glutathione Peroxidase

Glutathione peroxidase (GSH-PO), a selenium-dependent and lipid peroxide-scavenging enzyme that effectively reduces lipid peroxides with the concomitant oxidation of glutathione is distributed in mitochondria (1 ,2 ). Utsunomiya et al. (3 ) confirmed the dual localization of GSH-PO in the cytosol and mitochondria of normal rat hepatocytes. We have shown that short-term incubation with linoleic acids (LA) increased the thiobarbituric acid- reactive substance (TBARS) in the RPE cells, which indicated the level of lipid peroxides (4 ). Mitochondria in the RPE cells were swollen by the incubation with LA or linoleic acid hydroperoxide (LHP) (5 ). We speculate that exposure of RPE cells to LA or LHP may cause damage to the mitochondria by lipid peroxidation, resulting in the cytotoxicity of RPE cells. We also found loss of mitochondria of bovine RPE cells cultured in hypoxia as low as 1% oxygen, induced malfunction of phagocytosis and a decrease in antioxidants such as glutathione containing sulfur (6 ).