AJP - Regulatory, Integrative and Comparative Physiology, Vol 272, Issue 3 1002-R1006, Copyright © 1997 by American Physiological Society

ARTICLES

Lack of gurmarin sensitivity of sweet taste receptors innervated by the glossopharyngeal nerve in C57BL mice

Y. Ninomiya, M. Inoue, T. Imoto and K. Nakashima
Department of Oral Physiology and Chemistry, Asahi University School of Dentistry, Hozumi, Motosu, Japan.

Effects of a sweet response inhibitor, gurmarin, on responses of the chorda tympani and glossopharyngeal nerves were studied in the C57BL/KsJ strain of mice. The lingual application of gurmarin at 3.0 microg/ml (approxiamtely 0.7 microM) or more significantly suppressed chorda tympani responses to 0.5 M sucrose, as previously reported. The magnitude of gurmarin inhibition of the chorda tympani responses reached a plateau (approximately 45% of control) at 50 microg/ml (approximately 11.9 microM). In contrast, no such gurmarin inhibition of sucrose responses was observed in the glossopharyngeal nerve even at 100 microg/ml (approximately 23.8 microM). The lingual application of a proteolytic enzyme, pronase, suppressed sucrose responses to <20% of control in both chorda tympani and glossopharyngeal nerves. These results suggest differential sensitivity to gurmarin by sweet taste receptors innervated by the chorda tympani and the glossopharyngeal nerves. The former apparently possess gurmarin sensitivity, whereas most of the latter may be lacking sensitivity.

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