Cell death by 1-chloro-2,4-dinitrobenzene, an inhibitor of thioredoxin reductase and its dual regulation by nitric oxide in rats

Thioredoxin (Trx), the oxidized form of which is converted to a reduced for m by Trx reductase, regulates cell proliferation and survival. We investiga ted the effect of 1-chloro-2,4-dinitrobenzene (DNCB), an inhibitor of Trx r eductase, on cell death in neuronal PC12 cells and rat glial cells. In both types of cells, culture with DNCB for 4 h stimulated lactate dehydrogenase (LDH) leakage. LDH leakage by DNCB was inhibited by an inhibitor of caspas es. Addition of 2,2-(hydroxynitrosohydrazino)bis-ethanamine, of which 50% d ecays and releases nitric oxide (NO) in 21 h, inhibited DNCB-induced LDH le akage. Addition of 10 mu M N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino) -ethanamine (NOC-12), of which 50% decays and releases NO in 100 min, inhib ited DNCB-induced LDH leakage, although 0.2 mM NOC-12 enhanced the leakage in PC12 cells. These findings suggest that DNCB induces cell death of neuro nal and glial cells accompanied by caspase(s) activation. NO inhibits DNCB- induced cell death in both types of cells, although excess NO showed a toxi c effect. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.