Genistein attenuates D-galactose-induced oxidative damage through decreased reactive oxygen species and NF-κB binding activity in neuronal PC12 cells.

Aims: We investigated the mechanism of D-galactose (DG)-induced oxidative damage and the neuroprotective action of genistein in PC12 cells.

Main Methods: PC12 cells were treated with 40mM DG dissolved in medium containing 85% RPMI1640, 10% HBS and 5% FBS with or without genistein. We measured the protein expression of β-amyloid (Aβ), advanced glycation end products (AGEs), IκB-α and manganese-superoxide dismutase (MnSOD) by western blotting, intracellular reactive oxygen species (ROS) by 2, 7-dichlorofluorescin-diacetate, and the binding activity of nuclear factor kappa B (NF-κB) by electrophortic mobility shift assay.

Key Findings: DG (40mM) completely retarded cell growth after incubation for 72h, and this effect was not due to osmotic changes, as 40mM mannitol had no effect. Mechanistically, we found that DG increased intracellular ROS starting at 4h and increased Aβ and AGEs at 24h. DG treatment for 24h also increased the binding activity of NF-κB but strongly decreased the expression of IκB-α protein. Furthermore, DG treatment for 48h increased MnSOD protein expression. All these effects of DG were effectively inhibited by genistein (0.5-10μM).

Significance: The present study indicates that the protection of genistein against DG-induced oxidative stress in PC12 cells, and the effect is likely mediated by decreased intracellular ROS and binding activity of NF-κB.