Chemical Senses Advance Access originally published online on June 12, 2007
Chemical Senses 2007 32(7):689-696; doi:10.1093/chemse/bjm036
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Expression of Gustducin Overlaps with That of Type III IP3 Receptor in Taste Buds of the Rat Soft Palate
1 Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima-shi, Kagoshima 890-8544, Japan 2 Fundamental Research Laboratory, Asahi Breweries Ltd., 1-1-21 Midori, Moriya-shi, Ibaraki 302-0106, Japan 3 Gustatory Biology Laboratory, National Food Research Institute, 2-1-12 Kannondai, Tsukuba-shi, Ibaraki 305-8642, Japan
Correspondence to be sent to: Hirohito Miura, Oral Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima-shi, Kagoshima 890-8544, Japan. e-mail: hmiura{at}denta.hal.kagoshima-u.ac.jp
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Abstract |
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Type III IP3 receptor (IP3R3) is one of the common critical calcium-signaling molecules for sweet, umami, and bitter signal transduction in taste cells, and the total IP3R3-expressing cell population represents all cells mediating these taste modalities in the taste buds. Although gustducin, a taste cell–specific G-protein, is also involved in sweet, umami, and bitter signal transduction, the expression of gustducin is restricted to different subsets of IP3R3-expressing cells by location in the tongue. Based on the expression patterns of gustducin and taste receptors in the tongue, the function of gustducin has been implicated primarily in bitter taste in the circumvallate (CV) papillae and in sweet taste in the fungiform (FF) papillae. However, in the soft palate (SP), the expression pattern of gustducin remains unclear and little is known about its function. In the present paper, the expression patterns of gustducin and IP3R3 in taste buds of the SP and tongue papillae in the rat were examined by double-color whole-mount immunohistochemistry. Gustducin was expressed in almost all (96.7%) IP3R3-expressing cells in taste buds of the SP, whereas gustducin-positive cells were 42.4% and 60.1% of IP3R3-expressing cells in FF and CV, respectively. Our data suggest that gustducin is involved in signal transduction of all the tastes of sweet, umami, and bitter in the SP, in contrast to its limited function in the tongue.
Key words: taste bud, Trpm5, T1r 3, T2rs, whole-mount immunohistochemistry
Accepted 17 April 2007