TRPA1 modulates urocortin 1 turnover in the centrally projecting Edinger-Westphal nucleus in a CGRP-induced migraine model

The urocortin 1 (UCN1)-expressing neurons of the centrally projecting Edinger-Westphal nucleus (EWcp) regulate the function of migraine-related brain areas via direct urocortinergic connections. In the central nervous system, EWcp/UCN1 neurons uniquely co-expresses transient receptor potential ankyrin 1 (TRPA1) cation channel, which has also been linked to migraine. Here we aimed to investigate whether central TRPA1 receptors regulate the EWcp/UCN1 neurons' response to migraine. The intraperitoneal calcitonin gene related peptide (CGRP) injection model of migraine was implemented and validated using light-dark box and von Frey assays in wild-type (WT) and TRPA1 knockout (KO) male mice. RNAscope in situ hybridization and immunofluorescence were used to examine the Ucn1, Trpa1 mRNA expression and UCN1 peptide content in the EWcp. FOS immunohistochemistry was performed to assess acute neuronal activation in the EWcp and the antinociceptive lateral periaqueductal gray matter (lPAG). CGRP administration induced light aversion, periorbital hyperalgesia and increased FOS immunoreactivity in the lPAG in both genotypes supporting the model validity. Additionally, Trpa1 deficient mice exhibited reduced sensitivity to light, regardless of the treatment conditions. In the EWcp, CGRP treatment increased FOS immunosignal and Ucn1 mRNA expression in both genotypes. Moreover, in WT mice, the treatment increased the EWcp UCN1 peptide and Trpa1 mRNA levels, with no such changes observed in Trpa1 KO animals. These findings suggest a possible role of central TRPA1 in migraine by regulating UCN1 dynamics in the EWcp. Targeting TRPA1 ion channels through pharmacological interventions may offer a new strategy for migraine treatment.