Abstract:

BACKGROUND: Our preliminary studies have established a rabbit model of knee osteoarthritis using gypsum wire fixation, but the model of traditional Chinese medicine (TCM) syndrome of knee osteoarthritis has not been prepared.

OBJECTIVE: To assess the feasibility of establishing a rabbit model of yang deficiency and cold coagulation using peppermint oil and climate chamber, to lay the foundation for future research.

METHODS: Thirty-two experimental animals were randomly divided into normal group, model group, yang deficiency group and yang deficiency-cold coagulation group. Except for the normal group, the rabbit knee joints were fixed with plaster fixator brake method for 8 weeks. The yang deficiency group was given daily perfusion of peppermint oil for 2 weeks at the beginning of the 7^th week of fixation. In the yang deficiency-cold coagulation group, the rabbits were placed in a climate chamber at 4 °C for 1.5 hours every day, and given daily perfusion of peppermint oil after 6 weeks of braking. After 7 and 14 days of intragastric administration, the serum level of thyrotropin (T4) was detected by ELISA. After 8 weeks of modeling, the articular cartilage, meniscus and synovium were taken for histological scoring. Animal behaviors were observed, and body surface temperature was detected using an infrared thermal imager. The experimental protocol was approved by the Animal Ethics Committee of the First Affiliated Hospital of Xinjiang Medical University (approval No. IACUC-20170222026).

RESULTS AND CONCLUSION: For behavior observation, the symptoms of yang deficiency-cold coagulation appeared in the yang deficiency-cold coagulation group. The plantar temperature of the yang deficiency-cold coagulation was lower than that of the normal and model groups (P < 0.05). The serum T4 level was lower in the yang deficiency group and yang deficiency-cold coagulation group than the normal group (P < 0.05). The Mankin scores of the knee joints in two yang deficiency groups were both higher than that in the normal group (P < 0.05) but lower than that in the model group (P < 0.05). Hematoxylin-eosin staining of the meniscus and synovial membrane indicated the yang deficiency group and the yang deficiency-cold coagulation group had no significant difference from the model group. Histomorphological findings elucidated that the peppermint oil with climate box contributes to simulating the disease state to a certain extent, which can provide a reference for establishing the rabbit knee osteoarthritis model of yang deficiency-cold coagulation type.

Key words: knee arthralgia, knee osteoarthritis, peppermint oil, yang deficiency and cold coagulation