Effects of gymnemic acid on the chorda tympani proper nerve responses to sweet, sour, salty and bitter taste stimuli in the chimpanzee

Abstract

In man gymnemic acid is able to abolish the sweet taste. Also in man, the neural correlate of that effect is a disappearance of the response to sweet stimuli in the taste nerves, as indicated by the observations of Diamant et al. (1965). Although a variety of other mammals also show neural responses to sweet-tasting compounds, the corresponding effect of gymnemic acid has not been demonstrated. This study presents chorda tympani proper nerve recordings from the chimpanzee before and after gymnemic acid. On the chimpanzee tongue, application of 2 ml gymnemic acid (3-10 mg X ml-1 for 3-4 min) completely abolished the taste responses to 0.0035 M acesulfam-K, 0.0018 M aspartame, 0.015 M D-tryptophan, 0.02% monellin, and 0.02% thaumatin, reduced by 75% the response to 0.3 M sucrose, and by 50% that of 0.76 M xylitol. No decrease was recorded in the responses to 0.001 M quinine, 0.1 M NaCl, 0.02 and 0.04 M ascorbic acid, 0.02 and 0.04 M citric acid. The response to the sweeteners recovered with time and the recovery was complete or nearly complete after one and a half hours. It was also found that after application of 2 ml miraculin, 3 mg X ml-1 for 3 min to the tongue the neural response to acids was about 1.5 times as large as before. Gymnemic acid applied before miraculin prevented this enhancement and gymnemic acid after miraculin depressed the enhancement by miraculin of the response to citric and ascorbic acid.

The role of taste in food selection by African apes: implications for niche separation and overlap in tropical forests

“…Species differences were evaluated with t-tests. Two bottle preference tests correspond well to more sophisticated taste detection methods (Hellekant et al 1985), but are regarded as providing only a conservative approximation of a species' limits of gustatory capacity (Laska et al 1999a). We interpret the results of this work cautiously to avoid misinterpretation of data resulting from a too liberal criterion with a small data set.…”

“…Taste and texture discrimination affect food preferences and choices (Rozin 1983;Wene et al 1982) and are among the initial ways that primates can assess food quality before foods reach the gut for processing (Simmen 1994). Many differences in the sense of taste among primates appear to be phylogenetically related (Hellekant et al 1985;Steiner et al 1982) but, within groups, taste may play an important role in determining niche separation of closely related species (Glaser et al 1978;Simmen 1994). Taste sensitivity for sugars has been predicted to increase with body size (Laska et al 1999a(Laska et al , 1999b.…”

Expanded Terminal Fields of Gustatory Nerves Accompany Embryonic BDNF Overexpression in Mouse Oral Epithelia

“…All chemicals were reagent grade and prepared in artificial saliva (Hellekant et al, 1985). Neural responses were recorded to ascending concentrations series of 0.05, 0.1, 0.25, and 0.5 M NaCl, to 10, 20, and 50 mM citric acid, and then to 0.1, 0.25, 0.5 and 1.0 M sucrose.…”

Molecular Mechanisms for Sweet-suppressing Effect of Gymnemic Acids

“…It is known that GAs selectively suppress taste responses to various sweet compounds without affecting responses to salty, sour, and bitter substances for 30 -60 min after application of GAs in * This work was supported in whole or part by KAKENHI Grants 18109013, humans (21,22). The sweet-suppressing effect of GAs is specific to humans and chimpanzees; it has no effect on sweeteners for rodents (23)(24)(25)(26)(27). This effect is diminished by rinsing the tongue with ␥-cyclodextrin (CD) (28 -30).…”