Expression of substance P (NK1) receptor mRNA in human nose.

In airway tissues, it has been suggested that substance P is the transmitter of afferent sensory nerves which respond to various irritants and may be involved in airway allergic reactions. Three classes of tachykinin receptor are currently recognized, denoted as NK1, NK2 and NK3, which exhibit preferential affinity for substance P, neurokinin A and neurokinin B, respectively. We used molecular probes to study the gene expression and distribution of NK1 receptor in human nose. Total RNA was isolated from human nasal mucosa and NK1 receptor mRNA was detected in these tissues by using reverse transcription and polymerase chain reaction (RT-PCR). For in situ hybridization study of human nasal mucosa, we utilized the PCR directly to incorporate a T7 RNA polymerase promoter sequence onto the NK1 receptor cDNA, and these PCR products were used as the DNA templates for producing digoxigenin-labelled anti-sense and sense RNA probes. These studies revealed that NK1 receptor mRNA was expressed in submucosal glands and airway epithelium. The results may have an important clinical implication, and also promote further investigation of gene regulation of NK1 receptor in health and disease.