Curcumin Alleviates Adjuvant Arthritis in Rats via Inhibiting Proinflammatory Cytokine Secretion and Regulating Synovial Bcl-2/Bax Expressions

Rheumatoid arthritis is a common and refractory disease. Curcumin is a natural product which has many bioactivities. This study aimed to investigate the alleviation effects of curcumin on adjuvant arthritis (AA) in rats and the related mechanisms. Forty-eight rats were randomly divided into control, model, low-, medium-, and high-dose curcumin and leflunomide groups, 8 rats in each group. The AA model was established in later 5 groups. The rats in low-, medium-, and high-dose curcumin groups were treated with 20, 40, and 80 mg/kg curcumin, respectively. The leflunomide group was treated with 2 mg/kg leflunomide. The treatment was performed once per day, for 14 days. Results showed that, after treatment, compared with model group, in middle- and high-dose curcumin groups, and leflunomide group the paw swelling degree, arthritis index and serum tumor necrosis factor-alpha and interleukin-1 beta levels were significantly decreased (P < 0.05), the B-cell lymphoma 2 protein expression level in synovial tissue was significantly decreased (P < 0.05), and the B-cell lymphoma 2-associated X protein expression level was significantly increased (P < 0.05). In conclusion, curcumin can alleviate the AA in rats. The mechanism may be related to its inhibition of proinflammatory cytokine secretion and regulation of Bcl-2/Bax expressions.