HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL STUDIES OF DISTRIBUTION OF ACETYLCHOLINESTERASE-POSITIVE FIBERS AND PEPTIDERGIC TERMINALS IN THE NASAL-MUCOSA OF RATS

Objective To further investigate the mechanism of nasal secretion clos ely related to the innervation patterns in nasal mucosa with emphasis on the acetyl-cholinesterase (AChE)-positive fibers and peptidergic te rminals in nasal mucosa as well as trigeminal ganglion (TG) cells. Met hods Histochemical demonstration of AChE-positive fibers, immunohistoc hemical study of the distribution patterns of multiple peptidergic ter minals, double labelling of AChE and substance P (SP) and somatostatin (SOM) mRNA in situ hybridization were carried out in nasal mucosa and trigeminal ganglion (TG) in rats. Results AChE-positive terminals wer e mainly distributed in the mid to posterior one third of septal nasal mucosa, with greater staining density on the walls of small vessels a nd glands. There were fewer such terminals in turbinate mucosa. Tachyk inins-ergic terminals, including substance P(SP)-, neurokinin A (NKA)- , neurokinin B(NKB)- and calcitonin gene-related peptide (CGRP)-ergic terminals, had an extensive localizations in nasal mucosa, involving t he following areas: between epithelial cells, submucosa, the walls of small vessels, glands and venous sinusoids in both septal and turbinat e nasal mucosa. Septal mucosa had the greater density. There were over laps in the distribution of these peptidergic terminals. There were al so vasoactive intestinal peptide (VIP)-, neuropeptide Y (NPY)- and gal anin (GAL)-ergic terminals in nasal mucosa. But no neurotensin (NT)- a nd somatostatin (SOM)-ergic terminals were found. In situ hybridizatio n revealed SOMmRNA expression in TG cells. AChE and nine neuropeptides existed in the cytoplasms of TG cells. Besides, AChE and SP could exi st simultaneously in cytoplasms of TG cells. Conclusions AChE-positive (corresponding to parasympathetic nerves) and peptidergic terminals h ave different distribution patterns in the nasal mucosa of rats, altho ugh an overlap does exist, indicative of their different physiological effects on the regulation of nasal secretion and other functions; ACh E and multiple neuropeptides in the cytoplasm of TG cells might play a role in modulating the nasal secretion in response to stimuli in the nasal mucosa.