TRPV1 expressing extrinsic primary sensory neurons play a protective role in mouse oxazolone-induced colitis

TRPV1 expressing sensory neurons which have been considered to be largely associated with neurogenic inflammation were chemically denervated by capsaicin treatment in neonatal mice. However, neonatal capsaicin treatment aggravated mouse oxazolone-induced colitis, and did not affect the expression of calcitonin gene-related peptide (CGRP)- or substance P-immunoreactive nerve fibers in the colon. Meanwhile, the capsaicin-induced contraction was absent in the colon of neonatal capsaicin treatment mouse. These results suggest a protective role of TRPV1 expressing extrinsic sensory neurons in oxazolone-induced colitis and the involvement of some neurotransmitter other than CGRP and substance P in the pathogenesis of the colitis.