2022, Vol. 26 ›› Issue (23): 3756-3761

Protective effect of eucommia alcohol extract on articular cartilage of osteoarthritis model rats

Yang Demeng, Wang Changgeng, Hu Xinyuan, Ao Fei   

Abstract: BACKGROUND: At present, studies have found that eucommia water extract can significant relieve osteoarthritis, but there is no report about the therapeutic effect of eucommia alcohol extract on osteoarthritis.
OBJECTIVE: To investigate the protective effect of eucommia alcohol extract on osteoarthritis rats, and the mechanism of action of the janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3)/suppressor of cytokine signaling 3 (SOCS3) pathway.
METHODS: Sprague-Dawley rats were randomly divided into four groups (n=10 per group): a sham operation group, a model group, a low-dose eucommia alcohol extract group, and a high-dose eucommia alcohol extract group. Transection of the medial meniscotibial ligament of the right knee joint was conducted to induce an osteoarthritis rat model in all the groups except for the sham operation group. Rats in the low-dose and high-dose eucommia alcohol extract groups were given 50 and 200 mg/kg eucommia alcohol extract by intragastric administration for 8 weeks. Gait behaviors were tested, and paw withdrawal mechanical threshold and paw withdrawal thermal latency were determined. The changes of rat joint space and cartilage surface calcification were evaluated with X-ray imaging. The levels of inflammatory factors interleukin 6, interleukin 1β, and tumor necrosis factor α in rat serum were detected. Pathological changes of rat articular cartilage were observed using Safranin-O staining and hematoxylin-eosin staining, and were evaluated by Osteoarthritis Research Society International scoring system. Western blot was used to detect the protein expression of JAK1/STAT3/SOCS3 pathway in rat articular cartilage tissue.
RESULTS AND CONCLUSION: The rat cartilage surface was smooth in the sham operation group, but was severely damaged in the model group. Moreover, the cartilage surface density was increased, and the joint space became narrowed in the model group. Low- and high-dose eucommia alcohol extracts significantly relieved cartilage injury, and reduced surface calcification. Compared with the sham operation group, the Osteoarthritis Research Society International score, paw withdrawal mechanical threshold value, levels of interleukin 6, interleukin 1β, and tumor necrosis factor α, and protein expression of matrix metalloproteinase 13, JAK1, and p-STAT3 were significantly increased (P < 0.05), while the gait behavior score, paw withdrawal thermal latency and the protein expression of SOCS3 were significantly reduced in the model group (P < 0.05). Compared with the model group, the Osteoarthritis Research Society International score, paw withdrawal mechanical threshold value, levels of interleukin 6, interleukin 1β, tumor necrosis factor α, and protein expression of matrix metalloproteinase 13, JAK, and p-STAT3 were significantly reduced (P < 0.05), while the gait behavior score, paw withdrawal thermal latency and the protein expression of suppressor of cytokine signaling 3 were significantly increased in the low- and high-dose eucommia alcohol extract groups (P < 0.05). Therefore, eucommia alcohol extract can inhibit the JAK1/STAT3 pathway, promote the protein expression of SOCS3 and reduce inflammation, thereby protecting the articular cartilage of osteoarthritis rats.
Key words: eucommia alcohol extract, osteoarthritis, inflammatory response, janus kinase 1, signal transducer and activator of transcription 3, suppressor of cytokine signaling 3