Chapter 16: The solitary chemosensory cells the airways of mammals

Solitary chemosensory cells (SCCs) are present in the epidermis, oropharynx and gills of most primary aquatic vertebrates. They resemble taste bud cells but are distinguished from them by fine structural characteristics and by the fact that they do not aggregate into groups. Mammalian SCCs were first described in rats in 1998 and their presence was confirmed by further studies. Immunoreactivity for the G-protein subunit α-gustducin was found in SCCsas in taste bud cells. A recent study revealed the presence of SCCs in the respiratory apparatus of a large mammalian species (Bos Taurus) in which the airway cytology is similar to that of humans. The few findings in humans concern the nasal cavity, where cells with the morphology of SCCs have been found. These cells express Trp M5 and a subset of them also express gustducin, calbindin, and/or vesicular acetylcholine transporter. These early findings raise questions about the possible role of SCCs in the control of complex functions (e.g., airway surface liquid secretion or innate immunity), and about the involvement of chemoreceptors in respiratory diseases. Pharmacological action on SCCs could be important in the treatment of respiratory pathologies and might open new horizons in drug discovery.