ADCYAP1 and migraine disorder: Whereas CGRP is widely expressed on trigeminal neurons within the trigeminal ganglion, PACAP38 is found in far fewer trigeminal neurons,72, 81 but is more widely distributed in parasympathetic neurons, leading to interest in the involvement of this peptide in both migraine and the TACs; the latter include prominent cranial autonomic symptoms in their canonical phenotypes.