Induction of c-fos expression in forebrain cortex by 0.6% acetic acid stimulation. A-D. Representative photomicrographs of saline or acetic acid (i.p.) induced c-Fos expression in somatosensory SII cortex, insular cortex (IC) and SI cortex in wild type (WT) and transgenic (Tg) mice. The scale bar for panels A1-D1 and A4-D4 is 500 μm (low magnification), and the scale bar for A2-D2, A3-D3 and A5-D5 is 100 μm (high magnification). E1, Brain map  with photographed somatosensory SII and insular cortex framed in red. E2-3, Density of c-Fos positive cells in somatosensory SII cortex (E2) and Insular cortex (E3) of WT and Tg mice treated with saline or 0.6% acetic acid (i.p.). E4, Brain map  with the SI cortex framed in red. E5, Density of c-Fos positive cells in the SI cortex from WT and Tg mice treated with saline or 0.6% acetic acid (i.p.).Data are presented as mean ± s.e.m (n = 3-4, *p < 0.05, **p < 0.01).