Immunolocalisation of P2X and P2Y nucleotide receptors in the rat nasal mucosa

Purinoceptor subtypes were localised to various tissue types present within the nasal cavity of the rat, using immunohistochemical methods. P2X(3) receptor immunoreactivity was localised in the primary olfactory neurones located both in the olfactory epithelium and vomeronasal organs (VNO) and also on subepithelial nerve fibres in the respiratory region. P2X(5) receptor immunoreactivity was found in the squamous, respiratory and olfactory epithelial cells of the rat nasal mucosa. P2X(7) receptor immunoreactivity was also expressed in epithelial cells and colocalised with caspase 9 (an apoptotic marker), suggesting an association with apoptosis and epithelial turnover. P2Y(1) receptor immunoreactivity was found within the respiratory epithelium and submucosal glandular tissue. P2Y(2) receptor immunoreactivity was localised to the mucus-secreting cells within the VNO. The possible functional roles of these receptors are discussed.