2022, Vol. 26 ›› Issue (35): 5596-5601

Effect of warm acupuncture on PI3K/Akt signaling pathway in articular cartilage of a rabbit knee osteoarthritis model

Wu Yongli1, 2, Liu Di1, Wang Duo3, Liu Junwei1, Ma Yuyuan3   

Abstract: BACKGROUND: Warm acupuncture is an effective treatment for knee osteoarthritis; however, the therapeutic mechanism is not clear
OBJECTIVE: To observe the effects of warm acupuncture on PI3K/Akt signaling pathway and expression of downstream factors Bcl-2 and Bax in the articular cartilage of a rabbit model of knee osteoarthritis.
METHODS: Forty 6-month-old New Zealand rabbits were randomly divided into blank group, model group, glucosamine sulfate group and warm acupuncture group, with 10 rabbits in each group. The blank group was not modeled, and in the other three groups, the knee joint of the rabbit right hindlimb was immobilized in extension position using a plaster tube for 4 weeks to prepare the rabbit knee osteoarthritis model. After successful modeling, the blank group was not interfered. The rabbits in the model group were fixed in the rabbit frame for 15 minutes daily, those in the glucosamine sulfate group were treated with glucosamine sulfate by gavage at 77 mg/kg daily, and those in the warm acupuncture group were treated with warm acupuncture for 15 minutes daily, for 28 continuous days in total. After the intervention, hematoxylin-eosin staining was performed to observe the severity of cartilage damage. Cell apoptosis in chondrocytes was observed using TUNEL assay. mRNA and protein expressions of PI3K, Akt, Bcl-2 and Bax in cartilage tissue were detected by RT-PCR and western blot, respectively.
RESULTS AND CONCLUSION: The model group had a rough surface of articular cartilage, disordered arrangement and reduced number of chondrocytes, and significantly increased Mankin score, while the glucosamine sulfate and warm acupuncture groups showed increased number of chondrocytes, deeply stained matrix, and reduced Mankin score. Compared with the blank group, the apoptotic rate of chondrocytes was significantly increased in the model group (P < 0.05). Compared with the model group, the apoptotic rate of chondrocytes was significantly decreased in the glucosamine sulfate and warm acupuncture groups (P < 0.05). Compared with the blank group, the mRNA and protein expressions of PI3K, Akt and Bcl-2 were significantly decreased and the mRNA and protein expressions of Bax were significantly increased in the model group (P < 0.05). Compared with the model group, mRNA and protein expressions of PI3K, Akt and Bcl-2 were significantly increased and the mRNA and protein expressions of Bax were significantly decreased in the glucosamine sulfate and warm acupuncture groups (P < 0.05). To conclude, warm acupuncture can increase the expression of bcl-2 and decrease the expression of Bax by regulating PI3K/Akt signaling pathway, and then inhibit the excessive apoptosis of chondrocytes to protect articular cartilage.
Key words: knee osteoarthritis, warm acupuncture, chondrocyte apoptosis, PI3K/Akt signaling pathway, downstream factor