Chemical Senses Advance Access published online on August 9, 2007
Chemical Senses, doi:10.1093/chemse/bjm051
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Dopamine ß-Hydroxylase–like Immunoreactive Cells in the Frog Taste Disc
1 Department of Oral Physiology 2 Department of Oral Anatomy, Matsumoto Dental University School of Dentistry, Shiojiri 399-0781, Japan
Correspondence to be sent to: Hiroshi Ando, Department of Oral Physiology, Matsumoto Dental University School of Dentistry, Shiojiri 399-0781, Japan. e-mail: andohiroshi{at}po.mdu.ac.jp
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Abstract |
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We immunohistochemically examined the existence of dopamine ß-hydroxylase (DBH), a noradrenalin (NA)-synthesizing enzyme from dopamine, in the taste disc of frog, Rana catesbeiana. DBH-like immunoreactive cells were located in the intermediate layer in the taste disc; the cells showed an apical process reaching the surface of the disc and one or several basal processes. Cells with a thick apical process and those with a thin apical process were both immunoreactive: these cells corresponded to type II and III receptor cells of the frog taste disc. Immunoreactive granules were observed in the cytoplasm of those cells. In the frog taste disc, only type III cells are reported to have afferent synapses with the nerve via basal processes but those basal processes have not been reported in type II cells. In the present study, we found that type II–like cells possessed a long basal process extending toward the basal lamina. Mucous (type Ia) cells, wing (type Ib) cells, and glia-like sustentacular (type Ic) cells were all immunohistochemically unreactive. The present observations support the argument that NA (or adrenalin) may work as a chemical transmitter in the frog taste organ.
Key words: dopamine ß-hydroxylase, frog, glossopharyngeal nerve, neurotransmitter, noradrenalin, taste cell
Accepted 9 July 2007