Bergenin alleviates H2 O2 -induced oxidative stress and apoptosis in nucleus pulposus cells: Involvement of the PPAR-γ/NF-κB pathway.

Abstract

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 H2 O2 -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 H2 O2 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 H2 O2 -induced viability reduction and ROS overproduction in HNPCs in a dose-dependent manner. Bergenin alleviated H2 O2 -induced oxidative stress in HNPCs by increased activity of superoxide dismutase and level of glutathione peroxidase. H2 O2 -induced apoptosis and activity of caspase-3/7 were also suppressed by bergenin treatment in HNPCs. Western blotting showed that H2 O2 -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 H2 O2 -induced viability reduction, oxidative stress and apoptosis were noticeably abrogated in PPAR-γ knockdown HNPCs. In conclusion, our results indicated that bergenin alleviates H2 O2 -induced oxidative stress and apoptosis in HNPCs by activating PPAR-γ and suppressing NF-κB pathway.