TRPA1 and colitis: Moreover, DSS treatment up-regulates both CGRP+ and SP+ sensory nerve fibers and TRPA1 or TRPV1 KO mice have less upregulation of SP+ but not the CGRP+ sensory nerve fibers, suggesting that DSS-induced colitis is driven by TRPA1- and TRPV1-mediated release of SP (Utsumi et al., 2018; Fig. 2).