Fig. 3: Optostimulation of Tac2 neurons evoked itch-related scratching behavior.

a Schematic of blue light stimulation of Tac2^ChR2 neurons. b, c A snapshot (b) and quantification (c) of blue light-induced scratching behaviors in Tac2^ChR2 mice. One-way ANOVA with Tukey post-hoc, *p = 0.012. n = 6 mice per group. d The effect of i.t. morphine on blue light-induced scratches. Two-way ANOVA with Bonferroni post-hoc, ***p = 0.00001, n = 9 for Tac2^WT/saline, n = 7 for Tac2^WT/morphine, n = 11 for Tac2^ChR2/saline, n = 8 for Tac2^ChR2/morphine. e Blue light-induced scratches decreased after BB-sap treatment. Two-tailed Student’s unpaired t-test, *p = 0.029, n = 7 mice per group. f Double IHC of c-Fos (red) and GFP (green) in the spinal cord of Tac2^ChR2 mice following blue light stimulation. g Higher magnification of the boxed area in f. Arrowheads indicate double-stained c-Fos⁺/Tac2^ChR2+ neurons in f, g. Scale bars, 50 μm in f and 10 μm in g. h Quantification of percentages of Tac2^ChR2/c-Fos double positive neurons in c-Fos positive neurons in laminae IIi and IIIo, respectively. n = 3 mice. All data are presented as means ± s.e.m. and error bars represent s.e.m. Source data are provided as a Source Data file.