IMMUNOHISTOCHEMICAL LOCALIZATION OF NEUROPEPTIDES IN THE HUMAN CILIARY GANGLION

In human ciliary ganglia, 18% of neurons were in contact with substanc e P (SP) and 12% with calcitonin gene-related peptide (CGRP) like-immu noreactive (LI) varicose axons. CGRP was colocalized with SP. Numerous SP-LI and CGRP-LI non-varicose nerve fibers were found between the ga nglion cells and in nerve trunks that entered the ganglia. Axons immun oreactive for neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH) or dopamine-beta-hydroxylase (DBH) ne ver contacted neuronal cell bodies. Perikarya of ciliary neurons neith er stained for any of the neuropeptides nor for DBH. 23% of ciliary pe rikarya were TH-immunoreactive. These observations suggest an innervat ion of human ciliary ganglion neurons by peptidergic primary afferent collaterals presumably of trigeminal origin.