TRPV1 immunoreactivity in PGP9.5-positive structures in the distal colon. The specificity of the TRPV1 antibody was examined by pre-absorption assay showing that pre-incubation of TRPV1 antibody with a TRPV1 control peptide completely abolished the TRPV1-like immunoreactivity detected in the inflamed distal colon (compare B to A). Double immunostaining of the transverse section of the inflamed distal colon showed that TNBS-increased TRPV1 protein expression was localized in PGP9.5 positive structures (C-D, white arrows). Double immunostaining of the whole mount preparation of the submucosal plexus showed that TRPV1 was expressed in PGP9.5 positive fibers (F to H, white arrows). Note that not all PGP9.5 positive structures contain TRPV1 (C-H, blue arrows). Bar = 50 μm.