Neuropeptide expression in the human trigeminal nucleus caudalis and in the cervical spinal cord C1 and C2

In migraine and other primary headaches there is a strong vascular component. Besides the trigeminovascular components some of the associated symptoms point to the involvement of brain stem regions. The central limb of the trigeminal vascular pathway is its projection to the trigeminal nucleus caudalis (TNC) and to the C1-C2 levels of the spinal cord. The aim of the present study was to demonstrate the occurrence of some neurotransmitters in these regions in man. In both the TNC and in the Rexed's laminae I and II of the dorsal horns at the C1 and C2 levels there were numerous substance P immunoreactive fibres. Fibres containing calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP) were moderately dense in number. Fibres containing vasoactive intestinal peptide (VIP) or nitric oxide synthase (NOS) were not seen in the TNC or at the C1 and C2 levels of the spinal cord.