Effects of keishibukuryogan on vascular function in adjuvant-induced arthritis rats

It is known that rheumatoid arthritis (RA) accelerates atherosclerosis. Further, the soluble form of vascular adhesion molecule-1 (VCAM-1) is known as a predictive marker of atherosclerosis in RA patients. We reported that keishibukuryogan, one of the Kampo formulas, improved articular symptoms and decreased soluble VCAM-1 in patients with RA. In adjuvant-induced arthritis (AIA) rats, an animal model of RA, it is known that endothelial function is injured by inflammation. So, we investigated the effect of keishibukuryogan on endothelial function in AIA rats. Lewis rats were divided into control, AIA control, and AIA with keishibukuryogan groups. The AIA with keishibukuryogan group was fed 3% keishibukuryogan contained in normal chow. On day 25 after injection of Mycobacterium butyricum, endothelium-dependent relaxation by acetylcholine in the AIA control group was suppressed, but it was improved in the AIA with keishibukuryogan group. The contractions by xanthine/ xanthine oxidase in both AIA rats increased, but that in keishibukuryogan decreased compared to the AIA control group. Plasma levels of lipid peroxide increased in the AIA control group, but keishibukuryogan decreased these levels. Plasma levels of nitric oxide (NO) increased in both AIA groups. The expressions of endothelial NO synthase, inducible NO synthase and VCAM-1 of thoracic aorta were investigated by western blotting. These expressions increased in the AIA control group, but were restricted in the AIA with keishibukuryogan group. We considered that keishibukuryogan protected the endothelial function of AIA rats mainly by its antioxidative effect.