Oxidative stress in liver of brown bullhead and channel catfish following exposure to tert-butyl hydroperoxide

Reactive oxygen species (ROS) have been implicated in the etiology of liver neoplasia in mammals and fishes. Oxidation of DNA and lipid peroxidation m ay be important early markers of such damage in certain species and tissues , In this study, 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured in chann el catfish (Ictalurus punctatus) and brown bullhead (Ameriurus nebulosus) l iver after glutathione (GSH) depletion (with diethyl maleate/buthionine sul foximine injection) and exposure to the exogenous oxidant: tert-butyl hydro peroxide (t-BOOH). GSH depletion alone resulted in a significant increase i n lipid peroxidation in hepatic tissue of brown bullhead, but not in channe l catfish. GSH depletion alone did not result in a significant increase in 8-OHdG formation as assessed by high performance liquid chromatography and electrochemical detection in either species. Treatment with t-BOOH alone or in combination with GSH depletion did not affect levels of DNA oxidation i n either species. These results suggest that liver cells from these species of fish are relatively insensitive to the formation of oxidative DNA damag e following exposure to a severe oxidative stress, and that lipid peroxidat ion may be a more appropriate early marker of oxidative stress in liver of these species. (C) 1999 Elsevier Science B.V. All rights reserved.