Fig. 4

Unilateral cervical vagotomy blocked the inhibitory effect of curcumin on collagen II-induced arthritis in rats. Rats were subjected to unilateral cervical vagotomy (VGX) 4 days before collagen II-induced arthritis (CIA) was induced. Fourteen days after first immunization, curcumin (Cur, 100 mg/kg) and leflunomide (Lef, 2 mg/kg) were administered orally, and nicotine (Nic, 300 μg/kg) was intraperitoneally injected for 2 weeks. Rats were anesthetized by inhalation of ether 1 h after treatment on day 28, and serum was obtained. The cytokine levels were determined by ELISA. a Body weight changes. b Arthritis index scores. c Hind paws swelling. The volumes of hind paws were measured using a plethysmometer. d Representative ankle morphologies and pathomorphological changes of the ankle sections (H&E staining, original magnification ×100) in each group. After treatment for consecutive 2 weeks, the ankles of CIA rats were photographed. And then ankles of rats were removed, fixed, decalcified, and then stained with H&E to evaluate histological changes. e The total histological scores of ankle joint sections were summarized. f Serum concentrations of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and Th17 cell-related cytokine (IL-17A). g Serum concentrations of Th1, Th2, and Treg-related cytokines (IFN-γ, IL-4, IL-10, and TGF-β). Data were shown as means ± S.E.M. for each group (n = 6). *p < 0.05, **p < 0.01 vs. model group; ^#p < 0.05, ^##p < 0.01 vs. sham group; ^††p < 0.01 vs. VGX group; ^&&p < 0.01 vs. V-model group; ^$$p < 0.01 vs. Cur group