Peptide immunohistochemistry demonstrates multiple classes of perigemmal nerve fibers in the circumvallate papilla of the rat

Abstract

Taste papillae are associated with two distinguishable types of nerve fiber: (i) intragemmal fibers which are synapsed upon by the taste transducing cells of the taste bud; and (ii) perigemmal fibers which surround and sometimes penetrate into the taste buds. The perigemmal fibers exhibit immunoreactivity to antisera directed against either substance P or calcitonin gene-related peptide (CGRP). In double-label experiments, many perigemmal fibers exhibit immunoreactivity for both of these antigens. Other fibers, however, are immunoreactive only for substance P or CGRP. Thus, three distinguishable types of immunoreactive perigemmal fiber can be identified: only substance P-immunoreactive; only CGRP-immunoreactive; and doubly immunoreactive fibers.