Genistein as a neuroprotective antioxidant attenuates redox imbalance induced by beta-amyloid peptides 25-35 in PC12 cells.

OBJECTIVE: Genistein (GEN), a principal component of soybean isoflavones, might possess the neuroprotective role through its antioxidant activity. However, the detailed mechanisms are unknown yet. The purpose of this study was to investigate whether GEN could alleviate oxidative damage induced by beta-amyloid peptides 25-35 (Abeta25-35) in PC12 cells.

METHODS: The PC12 cells were pre-incubated with or without GEN for 2h following incubation with Abeta25-35 for another 24h. MTT was used to assess the cell viability. Hoechst 33342 staining was applied to determine the apoptotic cells. Confocal laser scanning microscopy was implemented to examine the reactive oxygen species (ROS) levels. Mitochondrial membrane potential (MMP) was measured by flow cytometry. Reduced and oxidized glutathione (GSH/GSSG) ratio was analyzed by using assay kits. Western blot analysis was performed to assess the proteins expression of NF-E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and gamma-glutamylcysteine synthetase (gamma-GCS).

RESULTS: GEN attenuated the cytotoxicity and partially prevented apoptosis induced by Abeta25-35. GEN dramatically attenuated ROS levels induced by Abeta25-35 in PC12 cells. In addition, GEN significantly reversed the reduction of MMP caused by Abeta25-35 to maintain the normal levels of the cells. The GSH/GSSG ratio in GEN pretreated groups significantly increased compared to the groups without GEN pretreatment. GEN reversed Abeta25-35 induced down regulation of the protein expression of gamma-GCS, Nrf2 and HO-1.

CONCLUSION: GEN could alleviate the oxidative stress caused by Abeta25-35 treatment and maintain redox balance in PC12 cells, which might be associated with the regulation of Nrf2/HO-1 signal pathway.