Establishment of a rat model of rheumatoid arthritis with kidney deficiency syndrome

To establish a rat model of rheumatoid arthritis (RA) with kidney deficiency syndrome.A total of 110 six-week-old specific pathogen-free male and female Sprague-Dawley rats were randomly divided into normal control group, sham-operated group, collagen-induced arthritis (CIA) control group, castration plus CIA group and hydroxyurea plus CIA group. Testiculus or ovary of rats in the castration plus CIA group was cut off, respectively. Rats in the hydroxyurea plus CIA group were given 375 mg/(kg·d) hydroxyurea by gavage administration for 17 d. Then rats in the CIA control group, castration plus CIA group and hydroxyurea plus CIA group were subcutaneously injected with mixture of type II collagen and incomplete Freund's adjuvant to induce rheumatoid arthritis. General state, arthritis index and joint swelling of the rats were observed to evaluate the onset of CIA. Contents of anti-type II collagen antibody, interleukin-6 (IL-6), IL-10, interferon-γ (IFN-γ) and corticosterone (CORT) in plasma were detected by enzyme-linked immunosorbent assay, and adrenal cyclic adenylic acid (cAMP) and cyclic guanylic acid (cGMP) levels were detected by radioimmunoassay.Compared with the CIA control group, the degrees of joint swelling and joint damage were significantly increased in the kidney-deficiency CIA rats (castration plus CIA group and hydroxyurea plus CIA group), with kidney deficiency syndrome similar to human clinical symptoms, such as depressed, bowed back, dullness, reduced diet and perianal contamination; the rats in those two groups were noted with a significantly decreased ratio of cAMP/cGMP; the content of CORT was increased in male rats while decreased in female rats, with an obvious increase in the content of anti-type II collagen antibody; the contents of IFN-γ, IL-6 and IL-10 were obviously increased in the castration plus CIA group.The rat model of RA with kidney deficiency syndrome has both obvious kidney deficiency syndrome and characteristics of RA and can reflect part of the patient's characteristics. However, castration is more suitable for inducing RA with kidney deficiency syndrome in rats.