Figure 4. Piezo2 contributes to visceral hypersensitivity in a mouse model zymosan-induced IBS.

(A). Representative images of colon preparations from vehicle- and zymosan-treated mice. Note the zymosan-treatment did not cause overt structural changes compared to vehicle-treated mice, n.s., no significant difference, unpaired t test, n=6. (B). Double labeling of DAPI (blue) and MPO (red) in colon preparations from vehicle- (left) and zymosan-treated (right) mice. Images shown here were representative of three independent experiments. Scale bar=100 μm. (C). Statistical data showing comparable numbers of MPO⁺ cells in zymosan-treated mice compared to the Sham-treated mice, n.s., no significant difference, unpaired t test, n=5 tissues from 5 mice. (D). Representative traces of whole-cell MA currents elicited by membrane displacement steps from CTB 488⁺ colon-innervating DRG neurons isolated from vehicle-treated and zymosan-treated mice. (E). Summary data of the proportions of DRG neurons responding with whole-cell MA currents in vehicle-treated and zymosan-treated mice. n=43 cells from 5 mice for vehicle group and n=38 cells from 5 mice for zymosan group. (F). Summary data of the maximal current density of inward whole-cell MA currents elicited at a holding potential of −80 mV in response to mechanical indentation. *P<0.05, unpaired t test. n=43 cells from 5 mice for vehicle-treated group and n=38 cells from 5 mice for zymosan-treated group. (G) Quantitative RT-PCR analysis of Piezo2 in L6 and S1 DRGs after zymosan treatment. *P<0.05, unpaired t test. n=7 mice for vehicle group and n=5 mice for zymosan group. (H). Representative traces of colon pelvic nerve recording of Piezo2^fl/fl and Trpv1^Cre::Piezo2^fl/fl mice subjected to zymosan treatment. (I). Summary data of stretch stimuli-induced nerve firings of colon nerve recording in Piezo2^fl/fl and Trpv1^Cre::Piezo2^fl/fl mice subjected to zymosan treatment. *P<0.05; ****P<0.0001, two-way ANOVA. n=14 units from 4 mice for Piezo2^fl/fl group and n=7 units from 3 mice for Trpv1^Cre::Piezo2^fl/fl group. (J). Schematic diagram showing the timing of zymosan treatment and VMR recording. (K). Summary data showing that zymosan-induced visceral hypersensitivity is significantly reduced in Trpv1^Cre::Piezo2^fl/fl mice compared to that in Piezo2^fl/fl mice. ****P<0.0001, two-way ANOVA, n=5 mice per group. All data are expressed as mean ± S.E.