Immunocytochemistry on the Localization of 5-Hydroxytryptamine in Monkey and Rabbit Taste Buds

Abstract

Immuno-electron microscopy with the protein A-gold method demonstrated immunoreactive gold particles against 5-hydroxytryptamine localized in cored vesicles aggregating around presynaptic terminals of the gustatory cells in monkey and rabbit taste buds. The positive reactions were also found in the intragemmal and sub-epithelial nerve fibers. The role of these cored vesicles in taste transduction is still uncertain but the data strongly suggest that they may participate in a serotonergic modulation of a cholinergic synaptic transmission from the gustatory cells to the nerve endings.

Fine structure of the taste bud in guinea pigs. I. Cell characterization and innervation patterns.

“…Formaldehyde-induced fluorescence histochemistry exhibits a yellow fluorescence characteristic of 5-HT in certain cells of the taste bud in rabbit foliate papillae (NADA andHIRATA, 1975, 1977). By immunoelectron microscopy, moreover, the 5-HT immunoreactivity is localized in dense-cored vesicles occurring in the type III cells of monkey and rabbit taste buds (FUJIMOTO et al, 1987). In the guinea pig, however, we failed to detect any 5-HT-immunoreactive cells in the taste bud (YOSHIE et al, unpublished data).…”

“…The vesicles contained in the cytoplasm of the type III cells, though variable in shape and size from species to species, are categorized into a small clear type and large dense-cored type. In most mammalian species hitherto investigated, the type III cells have contained small clear vesicles mingled with a few large dense-cored ones (JEPPSSON, 1969;MURRAY et Fine Structure of Guinea Pig Taste Bud, I 117 al., 1969;SANGIACOMO, 1970;PARAN et al, 1975;TAKEDA and HOSHINO, 1975;IDE and MUNGER, 1980;KONDO,1983;ZAHM and MUNGER, 1983a;FARBMAN et al, 1985;MURRAY, 1986;FUJIMOTO et al, 1987). In lower vertebrates, in contrast, corresponding cells have been demonstrated to tend to include exclusively either clear vesicles of the synaptic type (fish: HIRATA,1966;GROVER-JOHNSON and FARBMAN, 1976;ONO, 1980;FUJIMOTO and YAMAMOTO, 1980;TOYO-SHIMA et al, 1984a;see also UGA,1969) or dense-cored vesicles (frogs: GRAZIADEI and DEHAN,1971;HIRATA and NADA, 1975;TOYOSHIMA et al, 1984b;reptiles: UCHIDA, 1980).…”

Immunohistochemical Studies on Protein Gene Product 9.5, Serotonin and Neuropeptides in Vallate Taste Buds and Related Nerves of the Guinea Pig.

“…By formaldehyde-induced histofluorescence and immunocytochemistry, numerous investigators identifi-ed 5HT in mammalian taste buds and in frog taste discs (GoosENS and VANDERBERGHE, 1974;FUJIMOTO et al, 1987;KIM and ROPER, 1995). Recently, 5HT-like immunoreactivity has been found in taste cells of the rat, mouse and rabbit after administration of the 5HT precursor, 5-hydroxytryptophan (5HTP) (KIM and ROPER, 1995).…”

The Role of 5-HT3Receptors in Signaling from Taste Buds to Nerves

“…The 5-HT released by type III cells could also activate 5-HT 3 receptors on afferent nerve fibers. Type III cells (but not type II cells) form traditional synapses with afferent nerve fibers (Kinnamon et al, 1985;Yee et al, 2001;DeFazio et al, 2006) and synthesize and store 5-HT in dense-core synaptic vesicles located at these synaptic sites (Fujimoto et al, 1987). Therefore, 5-HT signaling to afferent nerve fibers could participate in the transmission of sour or some components of salty taste by type III cells.…”