Effects of H₂O₂ or NaN₃ on Thioredoxin Reductase in SH-SY5Y Cells

Abstract: Increasing experimental evidence demonstrated a role of oxidative stress in the pathogenesis of neurodegeneration diseases. Sodium azide (NaN₃) is a special inhibitor of mitochondrion cytochome c oxidase(COX)， and H₂O₂ can produce lots of free redicals， so both of them can mimic neuronal injury induced by oxidative stress. In this experiment， the neurotoxic effects of H₂O₂ or NaN₃ on SH-SY5Y cells were detected by means of cell viability measurement (MTT) and morphological observation. Moreover， the changes of intracellular thioredoxin reductase(TR)， the enzyme responsible for reduction of oxidized thiredoxin (Trx)， were analyzed through Western blotting and the intracellular distribution of TR was observed using immunohistochemical method. It was found that SH-SY5Y cells could be insulted by either NaN₃ or H₂O₂ in a dose-dependent manner. TR was identified in plasma， suggesting it is a secreted protein. A substantial down-regulation of TR in SH-SY5Y cells was only observed 3 h later following NaN₃-induced injury. This decrease in the antioxidative TR may contribute to the dysfunction of mitochondria and subsequent neurodegeneration.
    

CSTR: 32200.14.cjcb.2004.02.0021