Immunocytochemistry of neuron-specific proteins and neuropeptides in taste buds and associated nerves

The taste buds and associated nerves in the guinea pig, rat, cat, and mouse were investigated by immunocytochemistry and formaldehyde-induced fluorescence histochemistry. The antisera used were against spot 35 protein, neuron-specific enolase (NSE), neurofilament protein (NFP), and substance P. The spot 35 protein immunoreactivity was confined to taste bud cells in the guinea pig and rat; the immunoreactive cells, slender in shape, comprised half the number of the total taste bud cells in the guinea pig but were fewer in the rat. For NSE, on the other hand, taste bud cells as well as neural elements localized in both the taste bud and the subepithelial connective tissue were immunoreactive in all the species investigated. Furthermore, all of the spot 35 protein-immunoreactive cells proved to be NSE-immunoreactive in the guinea pig and rat. For NFP, neither the bud cells nor the nerves in the taste bud were reactive, whereas a part of nerves in the connective tissue was immunostained in all the species. The antiserum against substance P exclusively detected some parts of nerves in and out of the taste buds in the cat, rat, and mouse. The aminergic innervation was rather meager and appeared in the nerve fibers localized in the taste buds and connective tissue of the cat and mouse.