**Antagonism of Transient Receptor Potential Ankyrin Type-1 Channels as a Potential Target for the Treatment of Trigeminal Neuropathic Pain: Study in an Animal Model**

**Chiara Demartini 1,\*, Rosaria Greco 1, Anna Maria Zanaboni 1,2, Oscar Francesconi 3, Cristina Nativi 3, Cristina Tassorelli 1,2 and Kristof Deseure <sup>4</sup>**


Received: 17 September 2018; Accepted: 23 October 2018; Published: 25 October 2018

**Abstract:** Transient receptor potential ankyrin type-1 (TRPA1) channels are known to actively participate in different pain conditions, including trigeminal neuropathic pain, whose clinical treatment is still unsatisfactory. The aim of this study was to evaluate the involvement of TRPA1 channels by means of the antagonist ADM\_12 in trigeminal neuropathic pain, in order to identify possible therapeutic targets. A single treatment of ADM\_12 in rats 4 weeks after the chronic constriction injury of the infraorbital nerve (IoN-CCI) significantly reduced the mechanical allodynia induced in the IoN-CCI rats. Additionally, ADM\_12 was able to abolish the increased levels of TRPA1, calcitonin gene-related peptide (CGRP), substance P (SP), and cytokines gene expression in trigeminal ganglia, cervical spinal cord, and medulla induced in the IoN-CCI rats. By contrast, no significant differences between groups were seen as regards CGRP and SP protein expression in the pars caudalis of the spinal nucleus of the trigeminal nerve. ADM\_12 also reduced TRP vanilloid type-1 (TRPV1) gene expression in the same areas after IoN-CCI. Our findings show the involvement of both TRPA1 and TRPV1 channels in trigeminal neuropathic pain, and in particular, in trigeminal mechanical allodynia. Furthermore, they provide grounds for the use of ADM\_12 in the treatment of trigeminal neuropathic pain.

**Keywords:** neuropathic pain; trigeminal system; allodynia; TRPA1; TRPV1
