NITRIC-OXIDE SYNTHASE IN THE INNERVATION OF THE HUMAN NASAL-MUCOSA - CORRELATION WITH NEUROPEPTIDES AND TYROSINE-HYDROXYLASE

Nitric oxide (NO) is a powerful mediator in the central and peripheral nervous system. In the present study the authors have examined the hu man nasal mucosa innervation for the presence of the neuronal isoform of the NO-generating enzyme, NO-synthase (NOS), and its correlation wi th other neuronal mediators and markers by means of double-labeling im munohistochemistry. NOS-immunoreactive nerve fibers were observed to b e numerously present around glands and venous sinusoids and, less freq uently, around small arteries and veins. Few fibers were seen in the l amina propria. NOS appeared to be frequently colocalized in nerve fibe rs with vasoactive intestinal peptide and, occasionally, with substanc e P and tyrosine hydroxylase, a marker for catecholamine biosynthesis. These findings suggest that neurally released NO is an important regu latory mediator of glandular secretion and blood flow in the nasal muc osa.