PROSTAGLANDIN E(2) SYNTHESIS AFTER OXIDANT STRESS IS DEPENDENT ON CELL GLUTATHIONE CONTENT

The role of glutathione in protecting prostaglandin (PG) generation after exposure of fibroblasts to oxidant stress was investigated. Exposure of 3T3 fibroblasts to H2O2, followed by washing and then 20 mu M arachidonic acid, caused a dose-dependent decrease in PG synthesis as assessed by radioimmunoassay. PGE(2) production decreased from 3.7 +/- 1.1 to 0.15 +/- 0.04 pmol/mu g protein, and prostacyclin (PGI(2)) formation decreased from 0.56 +/- 0.03 to 0.06 +/- 0.03 pmol/mu g protein after exposure to 200 mu M H2O2 Decreasing intracellular glutathione with 50 mu g/ml 1,3-bis(chloroethyl)-1-nitrosourea (BCNU) enhanced the H2O2-induced decrease in PGE(2) synthesis. Another glutathione-depleting agent, 1-chloro-2,4-dinitrobenzene (CDNB), also potentiated the H2O2-induced decrease in PGE(2) formation. However, although PGI(2) production was decreased by H2O2, neither BCNU nor CDNB potentiated this decrease. Without oxidant stress, extreme glutathione depletion decreased PGE(2) synthesis and caused PGI(2) synthesis to exceed PGE(2). In summary, oxidant stress decreases both PGE(2) and PGI(2) formation. However, the primary effect of decreasing cell glutathione during oxidant stress is a reduction in PGE(2) formation, not PGI(2). This implies that the predominant effect of glutathione depletion during oxidant stress is on the PGE(2) isomerase(s) and not PGH synthase or PGI(2) synthase.