Mechanism of acupoint penetration acupuncture therapy regulating chondrocyte autophagy via the PI3K/Akt-mTOR pathway in KOA rats

Abstract

Objective: To investigate whether acupoint penetration acupuncture (APA) could regulate chondrocyte autophagy and apoptosis via the PI3K/Akt-mTOR signaling pathway to reduce cartilage degeneration in knee osteoarthritis (KOA) rats. Methods: KOA was induced in rats via intra-articular injection of sodium iodoacetate resolution. Forty male Sprague-Dawley rats were randomly assigned to blank control, model, APA, electro-acupuncture (EA), and sham model groups (n = 8) and those in the APA and EA groups received their respective therapies. Following completion of the treatment course, histological examinations of cartilage and muscle were conducted. Levels of apoptosis- and autophagy-related factors, including Bax, Bcl-2, mTOR, ULK-1, and Beclin-1 protein, and mRNAs were assessed. Additionally, β-endorphin (β-EP) concentrations in the brain and serum were measured. Results: Histological analysis revealed that APA alleviated cartilage and muscle damage compared with the model group. APA inhibited cartilage degeneration by modulating the expression of apoptosis- and autophagy-related proteins and mRNA, thus preventing chondrocyte apoptosis. In the APA group, Bax and mTOR protein levels were significantly lower than those in the model group (both P = .024). Conversely, the Bcl-2 expression level was significantly higher than that in the EA group (P = .035). Additionally, ULK-1 expression was significantly lower than that in the EA group (P = .045). The mRNA level of Bax was significantly higher than that in the blank control group (P < .001). However, Beclin-1 levels were significantly higher than those in both the model and EA groups (both P < .001). ELISA results showed a significant decrease in the concentration of β-EP in the brains of the rats in the APA group compared with those in the model group (P = .032). Conclusions: APA reduced osteoarthritis-related pain and alleviated cartilage damage by upregulating chondrocyte autophagy and down-regulating apoptosis via signaling pathways involving PI3K/Akt-mTOR in KOA rats.

Keywords

• Acupoint penetration acupuncture
• Knee osteoarthritis
• Chondrocyte
• Autophagy
• Apoptosis
• Cell proliferation