IMMUNOHISTOCHEMICAL DEMONSTRATION OF NITRIC-OXIDE SYNTHASE IN THE PERIPHERAL AUTONOMIC NERVOUS-SYSTEM

In the present immunohistochemical study the distribution of nitric ox ide synthase (NOS) was studied in various autonomic ganglia and in rel ated peripheral tissues of the rat. For comparison some other neuronal markers including acetylcholinesterase and tyrosine hydroxylase as we ll as several neuropeptides were analysed on adjacent or the same sect ions. The distribution of NOS-like immunoreactivity (LI) and of these other markers has been semiquantitatively summarized. In some parasymp athetic ganglia such as the sphenopalatine and submandibular ganglia N OS-LI was present in most ganglion cells, at least partly coexisting w ith peptide histidine isoleucine (PHI), vasoactive intestinal polypept ide (VIP) and neuropeptide tyrosine (NPY). In the pelvic ganglia a com paratively smaller proportion of neurons was NOS-positive and they oft en contained VIP-LI and less frequently NPY-LI. In the tissues innerva ted by these ganglia, such as nasal mucosa and salivary glands, NOS-po sitive fibers were observed around blood vessels and within the glandu lar parenchyma, although generally less abundant than VIP/PHI nerves, while in the uterus, vas deferens and penis a more close correlation w as seen. NOS-positive fibers were also widely distributed in other tis sues. In the sympathetic ganglia NOS-LI was mainly present in dense fi ber networks, which disappeared after transection of the sympathetic t runc central to the ganglion. Since many cell bodies in the sympatheti c lateral column of the spinal cord also were NOS-positive, it is like ly that the majority of preganglionic fibers innervating sympathetic g anglia are NOS-positive. VIP-positive cells in stellate ganglia did no t contain NOS-LI. The present results suggest that NO may be a messeng er molecule both in parasympathetic postganglionic neurons and in preg anglionic sympathetic neurons.