Yohimbine hydrochloride ameliorates collagen type‐II‐induced arthritis targeting oxidative stress and inflammatory cytokines in Wistar rats

Rheumatoid arthritis (RA) is the most common type of chronic inflammatory disease which is triggered by dysfunction in the immune system which in turn affects synovial joints. Current treatment of RA with NSAIDs and DMRDs is limited by their side effect. As a result, the interest in alternative, well tolerated anti‐inflammatory remedies has re‐emerged. Our aim was to evaluate the antioxidant and anti‐inflammatory activities underlying the anti‐RA effect of Yohimbine hydrochloride (YCL) in collagen induced arthritis (CIA) in Wistar rats. The YCL was administered at doses of 5 and 10 mg kg^?1 body weight once daily for 28 days. The effects of treatment in the rats were assessed by biochemical parameter (articular elastase, LPO, GSH, catalase, SOD), hematological parameter (ESR, WBC, C‐reactive protein (CRP), immunohistochemical expression (COX2, TNF‐α, and NF‐κB), and histological changes in joints. YCL showed anti‐RA efficacy as it significantly reduced articular elastase, LPO and catalase level and ameliorates histological changes. This is in addition to its antioxidant efficacy as YCL shown a significant increase in GSH and SOD level. Also, YCL showed effective anti‐inflammatory activity as it significantly decreased the expression of COX‐2, TNF‐α, and NF‐?B. The therapeutic effect of YCL against RA was also evident from lower arthritis scoring and reduced hematological parameter (ESR, WBC, and C‐reactive protein level). The abilities to inhibit proinflammatory cytokines and modulation of antioxidant states that the protective effect of YCL on arthritis rats might be mediated via the modulation of the immune system. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 619–629, 2017.