Bergenin alleviates H O -induced oxidative stress and apoptosis in nucleus pulposus cells: Involvement of the PPAR-γ/NF-κB pathway.

Bergenin is a C-glucoside of 4-O-methyl gallic acid with a variety of biological activities, such as antioxidant and anti-inflammatory. Herein, we investigated the involvement of bergenin in the protective effect against H O -induced oxidative stress and apoptosis in human nucleus pulposus cells (HNPCs) and the underlying mechanisms. HNPCs were cotreated with various concentrations of bergenin and 200 μM H O for 24 h. Cell viability was detected by Cell Counting Kit-8 and lactate dehydrogenase release assays. Reactive oxygen species (ROS) was evaluated utilizing 2',7'-dichlorofluorescein-diacetate. Superoxide dismutase (SOD) and catalase (CAT) activities and glutathione (GSH) levels were measured to assess oxidative stress. Apoptosis was evaluated using terminal deoxynucleotidyl transferase dUTP nick end labeling and caspase-3/7 activity assays. Expression of protein was determined by western blotting. Results indicated that treatment with bergenin significantly alleviated H O -induced viability reduction and ROS overproduction in HNPCs in a dose-dependent manner. Bergenin alleviated H O -induced oxidative stress in HNPCs by increased activity of superoxide dismutase and level of glutathione peroxidase. H O -induced apoptosis and activity of caspase-3/7 were also suppressed by bergenin treatment in HNPCs. Western blotting showed that H O -induced decrease in expression of peroxisome proliferator-activated receptor γ (PPAR-γ) and increase in nuclear factor κB (NF-κB) were inhibited by bergenin. However, the inhibitory effect of bergenin on H O -induced viability reduction, oxidative stress and apoptosis were noticeably abrogated in PPAR-γ knockdown HNPCs. In conclusion, our results indicated that bergenin alleviates H O -induced oxidative stress and apoptosis in HNPCs by activating PPAR-γ and suppressing NF-κB pathway.