FCA-induced rat model of rheumatoid arthritis and tissue preparation

After acclimatizing for 1 week, the RA model of experimental groups (20 rats) was established by the injection of 0.1 mL FCA into the plantar surface of the rat’s paw. The injection sites were right front paw/right hind paw to differentiate forelimb/hind limb of AA model (Liu et al. 2015). The control group containing 10 rats suffered the same volume of saline. On the seventh day after successfully induced by FCA, the anesthetized and bloodletting rats were prostrate on the sterile table. Then articular cavities were taken respectively. The marked articular cavities were promptly frozen by liquid nitrogen and then stored at ˗80 °C until RT-PCR experiment.