Fig. 3

Local effects: Non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) decreases colonic expression levels of pro-inflammatory markers in colitic mice and increases anti-inflammatory markers in non-colitic and colitic mice. taVNS (with stimulation parameters of 10 volts, a 500 µs pulse width, 30 s on/off duration, 10 min stimulation duration, and a frequency of 20 Hz) and no stimulation (anesthesia without any stimulation) were performed for the taVNS and CTRL (no stimulation) groups, respectively, beginning one day before the induction of acute colitis and continued daily until the mice were sacrificed. After 24 h, acute colitis was induced in the colitis (dextran sulfate sodium (DSS)) groups by adding 5% DSS to their drinking water for five days, while control groups continued to receive regular water. Colonic mRNA (A) and protein (B) levels of interleukin (IL)−1β, mRNA (C) and protein (D) levels of tumor necrosis factor (TNF)-α, mRNA (E) and protein (F) levels of transforming growth factor (TGF)-β, and mRNA (G) and protein (H) levels of IL-10, mRNA levels of macrophage inflammatory protein 1β (Mip1β) or chemokine (C-C motif) ligand 4 (CCL4) (I), matrix metalloproteinases 9 (MMP9) (J), MMP2 (K), and nitric oxide synthase 2 (Nos2) (L). One-way ANOVA and multiple parametric comparison tests (Bonferroni and Šídák) were used to calculate P values. The significance level was set at p < 0.05. n = 6–8 mice/group. Each value is presented as the mean ± SD. This experiment was repeated at least four times