Localization of substance P NK-1 receptors in rat tongue.

In rat tongue, neurons containing substance P terminate in connective tissue, in taste buds, and in lingual epithelium surrounding taste buds in fungiform, foliate and circumvallate papillae. Although many functions have been attributed to these neurons, virtually nothing is known about their physiological function. As a step towards this end, immunocytochemical methods were used to identify the NK-1 receptors (SPR) in rat tongue. SPR-IR was found in the basolateral membranes of taste cells in fungiform, circumvallate and foliate papillae. SPR-IR was not found in the dorsal epithelium or in any structure that could be clearly identified as a neuron. SPR-IR was also found in von Ebner's glands in circumvallate and foliate papillae and in blood vessels in connective tissue in all three papillae. These data suggest that substance P may play a role in taste and/or in oral pain.