Changes in activities of glutathione peroxidase and glutathione reductase during chemical hepatocarcinogenesis in the rat.
Changes in the activities of rat hepatic glutathione (GSH) peroxidase (GSH-Px) and GSH reductase (GR) were investigated during the induction of preneoplastic gamma-glutamyltransferase (gamma-GT)-positive foci and hyperplastic nodules by the administration of diethylnitrosamine followed by N-2-fluorenylacetamide. Activities of GSH-Px towards both cumene hydroperoxide (cumene-OOH) and hydrogen peroxide markedly decreased at an early stage of the above hepatocarcinogenesis, but the activity towards cumene-OOH again increased with the appearance of the foci and nodules, which were detectable as an increased gamma-GT activity. It was demonstrated by CM-Sephadex column chromatography and immunochemically that the increased activity towards cumene-OOH alone is due to the increased GSH-Px activity of GSH S-transferase B. GR activity and the total glutathione content in the liver also increased with increased preneoplastic foci and nodules. These results are discussed in connection with the protection mechanism(s) of these cell populations against damage by active oxygen and lipid peroxides produced in chemical hepatocarcinogenesis.
D000818:Animals; D004052:Diethylnitrosamine; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006965:Hyperplasia / Q000201:enzymology; D008054:Lipid Peroxides / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000139:chemically induced / Q000201:enzymology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D008054:Lipid Peroxides; D004052:Diethylnitrosamine; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase