Objective: To investigate the effect of inner-heating acupuncture on apoptosis of chondrocytes and expression of Caspase-3 and Caspase-9 in rats with knee osteoarthritis (KOA).
Methods: A total of 32 rats were divided into a normal group, a model group, a control treatment group and a treatment group by random number grouping method, 8 rats in each one. The rats in the normal group received no intervention. The rats in the remaining three groups adopted modified Videman method to develop KOA model, the ankle joint of left posterior leg was fully extended and fixed with a resin bandage for 6 weeks. After successful modeling, the rats in the model group received no intervention. The rats in the control treatment group were treated with medium-frequency pulse electrotherapy. The rats in the treatment group were treated with inner- heating acupuncture, 30 min each treatment, once a day, five days per week, and totally 3-week treatment was given. After 3 weeks, the damaged cartilage tissue was collected, and HE staining was used to observe the pathological changes of the cartilage tissue of the knee joint. ELISA was used to detect the content of cytochrome-C in the tissue homogenate supernatant. The chondrocytes in damaged cartilage tissue were isolated, flow cytometer was used to detect the changes of apoptosis and mitochondrial membrane potential. The mRNA and protein expression of Caspase-3 and Caspase-9 in chondrocytes were detected by real-time quantitative PCR (qRT-PCR) and Western blot (WB), respectively.
Results: Compared with the normal group, the damage of cartilage tissue in the model group was significant, and the expression level of Cyt-C in the homogenate supernatant of damaged cartilage tissue was increased (P<0.01); the chondrocyte apoptosis was increased significantly (P<0.01); the chondrocyte mitochondrial membrane potential was decreased significantly (P<0.01); the mRNA and protein expression of Caspase-3 and Caspase-9 was increased significantly (all P<0.01). Compared with the model group, the cartilage injury in the control treatment group and the treatment group was significantly relieved; the expression level of Cyt-C in the supernatant of damaged cartilage tissue homogenate was decreased (both P<0.01); the chondrocyte apoptosis was significantly reduced (both P<0.01); the chondrocyte mitochondrial membrane potential was increased significantly (both P<0.01). Moreover, the mRNA and protein expression of Caspase-3 and Caspase-9 was significantly reduced (all P<0.01). Compared with the control treatment group, the treatment group was more effective in the treatment of KOA.
Conclusion: The inner-heating acupuncture could significantly improve the pathological changes of KOA rats, inhibit the apoptosis of chondrocytes, which may be closely related to the suppression of Caspase-3 and Caspase-9 expression.
Keywords: Caspase-3 and Caspase-9; apoptosis; chondrocytes; inner-heating acupuncture; knee osteoarthritis (KOA).