Glycoconjugate in Rat Taste Buds.

Abstract

ABSTRACT. The taste buds of the fungiform papillae, circumvallate papilla, foliate papillae, soft palate and epiglottis of the rat oral cavity were examined by lectin histochemistry to elucidate the relationships between expression of glycoconjugates and innervation. Seven out of 21 lectins showed moderate to intense staining in at least more than one taste bud. They were succinylated wheat germ agglutinin (s-WGA), Dolichos biflorus agglutinin (DBA), Bandeiraea simplicifolia lectin-I (BSL-I), Ricinus communis agglutinin-I (RCA-I), peanut agglutinin (PNA), Ulex europaeus agglutinin-I (UEA-I) and Phaseolus vulgaris agglutinin-L (PHA-L). UEA-I and BSL-I showed moderate to intense staining in all of the taste buds examined. They strongly stained the taste buds of the epiglottis, which are innervated by the cranial nerve X. UEA-I intensely stained the taste buds of the fungiform papillae and soft palate, both of which are innervated by the cranial nerve VII. The taste buds of circumvallate papilla and foliate papillae were innervated by the cranial nerve IX and strongly stained by BSL-I. Thus, UEA-I and BSL-I binding glycoconjugates, probably α-linked fucose and α-D-galactose, respectively, might be specific for taste buds. Although the expression of these glycoconjugates would be related to the innervation of the cranial nerve X, the differential expression of α-linked fucose and α-D-galactose might be related to the innervation of the cranial nerve VII and IX, respectively. KEY WORDS: glycoconjugate, innervation, lectin-histochemistry, rat, taste bud.The gustatory sense is one of four special senses in mammals. The gustatory sense is transmitted by the taste buds distributed in the oral cavity and laryngopharynx. The taste buds, composed of 40-70 cells with different cell types, have a complex structure and access to the oral cavity via the taste pore [2,10,12,17,23]. They can catch chemical materials in the solvent and transmit the signals to the central nervous system. In mammals, the taste buds are observed in fungiform papillae, circumvallate papillae, foliate papillae, soft palate and epiglottis where individual taste bud is innervated by only one of three kinds of the cranial nerves, VII, IX, and X. Taste buds of fungiform papillae, anterior region of foliate papillae and soft palate were innervated by chorda tympani of the cranial nerve VII [14]. Taste buds of circumvallate papilla and posterior region of foliate papillae were innervated by the cranial nerve IX and those of epiglottis were innervated by the cranial nerve X in the rat [14]. These cranial nerves have crucial roles for the development, maintenance and regeneration of the taste buds in the rat [3,4,11,13,15,24].The glycoconjugates on the surface of taste bud cells were involved in chemosensory regulation in olfactory cilia of the channel catfish [5]. The carbohydrate components in the taste buds of circumvallate papillae were detected by lectin histochemistry in the Syrian hamster [16]. In the tongue of various vertebrates, Witt et al. showed ma...

Comparative Lectin Histochemical Studies on Taste Buds in Five Orders of Mammals

“…Since beta-N-acetylglucosamine is ubiquitously localized in all types of papillae in all mammals examined, it might play an essential role in the taste bud function. As for alpha-fucose, the present results positively correlated with the previous reports on the localizations of glycoconjugates in the rat [4], rabbit, frog and fish [3,4,[14][15][16][17][18]. In contrast, certain glycoconjugates were unique in some but not all types of papillae, such as alpha-N-acetylgalactosamine, alpha-mannose and alpha-D-glucose.…”

“…WGA, s-WGA, LEL and STL bind to beta-N-acetylglucosamine), the binding patters of these lectins differed greatly among animals and/or taste papillae. As it has been postulated that lectins identify three-dimensional structures of glycoconjugates [4], the present results suggest the differences in the spatial molecular structures of glycoconjugates that even when cells in the taste buds show the same distribution patterns of lectin bindings. Specific bindings to certain types of cells have been reported in the tongue [11,13]; for example, Taniguchi, et al (2005) reported that PNA bound to type IV cells of the rat taste buds [13].…”

“…Kano et al (2001) suggested the possibility that nerves innervating the taste papillae might have some effect on the types of glycoconjugates [4]. The taste buds located in the anterior two-thirds of the tongue are innervated by the chorda tympani nerve, while the taste buds located in the posterior one-third of the tongue are innervated by the glossopharyngeal nerve [2,9].…”

“…Based on the molecular structures of these receptors, it has been postulated that at least some of the receptors are glycoproteins, exposed to the extra-cellular surface of taste cells [7], and supposed to have a role in perceiving taste sensations. On the other hand, although several lectin histochemical studies have been reported until now, all of them reported only on a single species, such as rabbits [15], frogs [3] and teleost [16][17][18] and rats [4,14]; and no comparative studies have been made on different mammalian species in one report. In the present study, therefore, we lectin histochemically examined the cells of taste buds in the lingual papillae to determine and compare the types and compositions of glycoconjugates in five orders of mammalian species: artiodactyl, perissodactyl, rodent, carnivore and primate.…”

Lectin Histochemistry of Taste Buds of the Rat Tongue Circumvallate Papilla under Normal Conditions and in Glutamate-Induced Obesity

“…Багато дослідників вивчали експресію глікоко-н'югатів у клітинах смакових бруньок різних тварин з використанням методів лектинової гістохімії, як корисного інструменту для визначення вуглевод-них детермінант клітинної поверхні. Лектини вико-ристовуються для ідентифікації конкретних популя-цій клітин на основі різної спорідненості з різними вуглеводними епітопами поверхні клітинної мемб-рани, а також дозволяють вивчати динаміку пере-розподілу глікокон'югатів у складі клітин та екстра-целюлярних структур як у фізіологічних умовах, так і при патології [11][12][13][14][15].Мета дослідження. З використанням методів лектинової гістохімії дослідити вплив натрієвої солі глутамінової кислоти на вуглеводні детермінанти структурних компонентів жолобуватого сосочка язика.…”