Localization of m3 Muscarinic Receptor mRNA in Human Nasal Mucosa

Cholinergic nerves play an important part in the regulation of nasal secretions and nasal patency. In situ hybridization was used to identify the cells in human nasal mucosa that express the muscarinic m3 receptor mRNA, which codes for the M3 muscarinic receptor subtype protein. An m3 cDNA probe was biotin-labeled using terminal transferase and hybridized to tissue sections of formaldehyde- or formaldehyde/microwave irradiation-fixed human nasal mucosa. The biotinylated probe was detected using gold-labeled antibiotin antibodies with silver enhancement. Muscarinic m3 receptor mRNA was identified in all epithelial cells, both serous and mucous cells of submucosal glands, and endothelial cells of small muscular arteries, veins, and capillaries. This suggests that M 3 receptors may mediate glandular secretion and vasomotor effects. M 3 -receptor antagonists active at these sites may reduce the glandular secretion and vasodilation that is produced by parasympathetic reflex activity in allergic and nonallergic rhinitis.