Ligustilide attenuates nitric oxide‐induced apoptosis in rat chondrocytes and cartilage degradation via inhibiting JNK and p38 MAPK pathways

Ligustilide (LIG) is the main lipophilic component of the Umbelliferae family of pharmaceutical plants, including Radix angelicae sinensis and Ligusticum chuanxiong. LIG shows various pharmacological properties associated with anti‐inflammation and anti‐apoptosis in several kinds of cell lines. However, the therapeutic effects of LIG on chondrocyte apoptosis remain unknown. In this study, we investigated whether LIG had an anti‐apoptotic activity in sodium nitroprusside (SNP)‐stimulated chondrocyte apoptosis and could delay cartilage degeneration in a surgically induced rat OA model, and elucidated the potential mechanisms. In vitro studies revealed that LIG significantly suppressed chondrocyte apoptosis and cytoskeletal remodelling, which maintained the nuclear morphology and increased the mitochondrial membrane potential. In terms of SNP, LIG treatment considerably reduced the expression levels of cleaved caspase‐3, Bax and inducible nitric oxide synthase and increased the expression level of Bcl‐2 in a dose‐dependent manner. The LIG‐treated groups presented a significantly suppressed expression of activating transcription factor 2 and phosphorylation of Jun N‐terminal kinase (JNK) and p38 mitogen‐activated protein kinase (MAPK). The inhibitory effect of LIG was enhanced by the p38 MAPK inhibitor SB203580 or the JNK inhibitor SP600125 and offset by the agonist anisomycin. In vivo studies demonstrated that LIG attenuated osteoarthritic cartilage destruction by inhibiting the cartilage chondrocyte apoptosis and suppressing the phosphorylation levels of activating transcription factor 2, JNK and p38 MAPK. This result was confirmed by histological analyses, micro‐CT, TUNEL assay and immunohistochemical analyses. Collectively, our studies indicated that LIG protected chondrocytes against SNP‐induced apoptosis and delayed articular cartilage degeneration by suppressing JNK and p38 MAPK pathways.