The mucociliary transport system is a crucial defense mechanism in the airways. This system is dependent on both the ciliary beats and the properties of the periciliary fluid. In the nasal mucosal epithelial surface, there are two major types of cells which play an important role in the system, ciliated cells and goblet cells. In this study, we used the nasal mucosa of rats and examined the effects of neuropeptides which coexist in the nociceptive trigeminal sensory nerves, i.e., substance P (SP), neurokinin A (NKA), and calcitonin gene-related peptide (CGRP), on these two types of cells by a videoenhanced microscopic technique. We could observe ciliated cells and epithelial goblet cells on the same preparation simultaneously. The effect on ciliated cells was estimated by measuring the frequency of ciliary beat with a fast Fourier transformation (FFT) analyzer (ciliary activity), and the effect on goblet cells was evaluated by counting every exocytotic response in a single goblet cell (secretory activity).
SP (1μM) significantly promoted both secretory activity and ciliary activity. NKA (1μM) also stimulated the secretory responses of goblet cells significantly, and promoted the ciliary activity. Increased secretion of goblet cells were induced by SP and NKA simultaneously or a few seconds later when ciliary activity was accelerated. These two responses seemed to be functionally cooperative. In contrast, CGRP (1μM) did not stimulate secretory or ciliary activity.
We showed that neuropeptides in the trigeminal sensory neurons are involved in regulating both ciliated cells and goblet cells and play an important role in host defense mechanism in the rat.