Baicalin prevents the apoptosis of endplate chondrocytes by inhibiting the oxidative stress induced by H2O2

Osteoarthritis (OA) is a degenerative disease of articular cartilage. The pathogenesis of OA remains to be fully elucidated, and several studies have found that oxidative stress is important in its pathogenesis. Baicalin is well known and has already been investigated for its role of inhibiting the oxidative stress pathway. Thus, the present study aimed to investigate the role of baicalin on the inhibition of oxidative stress in endplate chondrocytes induced by hydrogen peroxide (H2O2). Following treatment of endplate chondrocytes with different doses of H2O2 with or without baicalin for different incubation durations, a CCK-8 assay and Annexin V/PI staining were used to measure the cell proliferation and apoptotic rates to identify the optimal experimental conditions. Subsequently, for examining the effects and underlying mechanism of baicalin on oxidative stress, the protein expression levels of cleaved-poly (ADP-ribose) polymerase (PARP), B-cell lymphoma-2-associated X protein (Bax) and pro-caspase-3 were analyzed using western blot analysis, intracellular anti-oxidant activities, including those of malondialdehyde (MDA), superoxide dismutase (SOD) and nitric oxide (NO), were quantified, and the levels of endothelial nitric oxide synthase (eNOS) were examined using reverse transcription-polymerase chain reaction analysis. The results revealed that the oxidative stress of endplate chondrocytes induced by 0.5 mM H2O2 for 4 h were the most appropriate conditions for experiments, and pretreatment with 100 ae mol/l baicalin for 1 h effectively reversed the effect of H2O2 on the endplate chondrocytes. In addition, Annexin V/PI staining demonstrated that the cell death induced by H2O2 was apoptotic, and baicalin reversed the apoptosis induced by oxidative stress. H2O2 activated PARP cleavage, and the expression of Bax and pro-caspase-3; however, baicalin inhibited the expression of these apoptotic signaling indicators. Baicalin also reduced the levels of MDA, and increased the levels of SOD and NO. Baicalin also significantly elevated the mRNA levels of eNOS in endplate chondrocytes. Therefore, the results of the present study showed that baicalin significantly inhibited the oxidative stress in endplate chondrocytes induced by H2O2, and decreased cell apoptosis.