Sex-related responses to oxidative stress in primary cultured hepatocytes of European flounder (Platichthys flesus L.)

Effects of oxidative stress induced by xenobiotic compounds were studied in primary cultures of isolated hepalocytes of immature European flounder (Pl atichthys flesus L.) of both sexes caught in a relatively unpolluted area o f the German Eight (North Sea). Cells were exposed to oxidative stressors s uch as 100 muM hydrogen peroxide (H2O2), 100 muM benzo[a]pyrene (B[a]p) and 50 muM nitrofurantoin (N-(5-nitro-2-furfurylidene)-1-aminohydantoin; NF) f or 2 and 24 h. Cell mortality was determined with the use of the fluorescen t ethidium homodimer-1 and calcein. Oxidative stress response was assessed by quantitative analysis of (1) intracellular reactive oxygen species (ROS) formation with dihydrorhodamine 123, (2) lipid peroxidation on the basis o f concentrations of lipid hydroperoxides and the lipid peroxidation product s malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) and (3) cellular total oxidant-scavenging capacity (TOSC) using the TOSC assay (Winston et al., 1 998). An increase in ROS formation was detected as early as 2 h after expos ure to H2O2, B[a]p and NF. After 24 h, stress responses were lower, except following exposure to NF. The pattern of responses differed with the differ ent oxidative stressors. Lipid peroxidation and the capacity to scavenge RO S were increased significantly in both sexes only after exposure to H2O2, w hereas B[a]p and NF provoked sex-dependent responses. B[a]p-induced lipid p eroxidation and increase in scavenging capacity were observed only in hepat ocytes of females, whereas NF initiated these responses only in cells of ma les. Sex differences in oxidative stress response only after exposure to pr o-oxidants that require enzymatic activation infer the importance of biotra nsformation pathways in stress responses. Because of their sensitivity to o xidative stress, flounder hepatocytes provide a useful model for early risk assessment of xenobiotics. (C) 2001 Elsevier Science B.V. All rights reser ved.