Immunohistochemical and enzymehistochemical studies of peptidergic, aminergic and cholinergic innervation of the lacrimal gland of the monkey ( Macaca fuscata)

Abstract

The distribution of nerve fibers containing peptides which include calcitonin gene-related peptide (CGRP), substance P (SP), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) and enzymes of tyrosine hydroxylase (TH) and acetylcholinesterase (AchE) in the lacrimal gland of the monkey ( Macaca fuscata) was studied using immunohistochemical and enzymehistochemical methods. We also examined the trigeminal ganglion (TG) and superior cervical ganglion (SCG) using the same methods. All peptide- and enzyme-containing nerve fibers examined in this study were present in the lacrimal gland and a consistent distribution pattern for each substance was found. CGRP-immunoreactive (IR) nerve fibers were mainly distributed around the blood vessels in the interlobular connective tissue. The distribution pattern of SP-IR nerve fibers was similar to that of CGRP-IR nerve fibers, but they were much less in number. NPY-IR nerve fibers were observed mostly around the blood vessels and occasionally in the interstitial stroma between the acini. Numerous VIP-IR nerve fibers were found surrounding the acini, ducts and blood vessels. TH-IR nerve fibers were also been around the blood vessels and in the interstitial stroma between the acini, as were NPY-IR fibers. The highest concentration of acetylcholinesterase (AchE)-positive nerve fibers was present in the acini, ducts and blood vessels, showing a similar distribution to VIP-IR fibers. In the TG, 50% of medium and 30% of small ganglion cells were CGRP-IR cells, while 20% of medium and 25% of small ganglion cells were of the SP-IR types. In the SCG, on the other hand, all ganglion cells showed TH-immunostaining, and NPY-IR cells were found in 10% of large and 25% of small ganglion cells. These results suggest that different modes of innervation can affect differently the secretory function of the lacrimal gland of the monkey.