Abstract
The localization of cholinesterase activity in the tongue of albino rats was histochemically demonstrated by the thiocholine technique of Koelle and Friedenwald, modified by Gomori. The taste nerve fibers innervating the taste buds in the vallate and fungiform papillae contained cholinesterase of both true and pseudo types, the former being predominant. The taste buds themselves failed to show definite cholinesterase activity. True and pseudo cholinesterases were also found in the different sensory nerve endings in the lingual papillae, in the subepithelial nerve plexus, in the motor end plates of the lingual muscle, and in the autonomic nerve fibers innervating the serous Ebner's gland, mucous Weber's gland and the arterioles.
The cholinesterase activity in the taste bud areas was found to be in-hibited by several kinds of bitter-tasting substances, including quinine hydro-chloride, methantheline bromide, berberine hydrochloride, L-methylephedrine hydrochloride, phenobarbital sodium and sodium dehydrocholate. Among the bitter substances tested, only phenylthiocarbamide, a substance with dual taste reaction, failed to inhibit the cholinesterase. Sweet-tasting substances such as sucrose, sodium cycloheylsulfamate and saccharin sodium were all ineffective in inhibiting cholinesterase. It was suggested that the inhibition of cholinesterase activity in the vicinity of taste buds may be associated with the mechanism of bitter taste.
