| Objective To investigate the effects of leonurine on autophagy and apoptosis of chondrocytes and the role of PTEN-induced putative kinase 1 (PINK1)/Parkinson's disease protein (Park) signaling pathway in osteoarthritis (OA) rats. Methods Standard anterior cruciate ligament transection (ACLT) was applied to construct an OA rat model. The successfully modeled rats were divided into OA group, leonurine L group, leonurine M group, and leonurine H group, with 12 rats in each group. Other 12 rats were collected as the sham operation group. HE staining was applied to detect the morphological changes of chondrocytes of rats in each group. Transmission electron microscopy was applied to observe the ultrastructure of chondrocytes of rats in each group. TUNEL method was applied to detect chondrocyte apoptosis of rats in each group. RT-qPCR was applied to detect the mRNA expression levels of PINK1, Parkin, P62, and LC3B in the cartilage tissue of rats in each group. Western blotting was applied to detect the expression levels of PINK1, Parkin, P62, and LC3B proteins in the cartilage tissue of rats in each group. Results Compared to that in the sham surgery group, the cartilage morphology of rats in the OA group was abnormal, the structure was blurry, the cracks appeared on the surface, the number of mitochondria in chondrocytes reduced, and a small amount of autophagosomes were present. The apoptosis rate of chondrocytes and the levels of P62 mRNA and protein in the cartilage tissue increased significantly. The mRNA and protein levels of PINK1, Parkin, and LC3B in the cartilage tissue reduced significantly (P<0.05). Compared to those in the OA group, the cartilage morphology of the rats in the leonurine L, M, H groups gradually recovered, the structure gradually became clear, surface cracks decreased, the number of chondrocytes restored, mitochondria increased, and the number of autophagosomes increased. The apoptosis rate of chondrocytes and the mRNA and protein levels of P62 in the cartilage tissue reduced significantly. The mRNA and protein levels of PINK1, Parkin, and LC3B in the cartilage tissue increased with a dose-dependent manner (P<0.05). Conclusion Leonurine may promote autophagy and inhibit chondrocyte apoptosis in OA rats by activating the PINK1/Parkin signaling pathway. |