SUMMARY1. The gustatory effects of miraculin, the sweetness-inducing protein from the miracle fruit Synsepalum dulcificum, was studied in the rhesus monkey, Macaca mulatta.2. The intake of five acids was recorded in two-bottle preference tests, one bottle containing acid and the other tap water, before and after miraculin treatment. All the acids tasted more pleasant after miraculin.3. The electrical activity of the chorda tympani nerve to stimulation of the tongue with a variety of sweeteners, acids, sodium chloride and quinine hydrochloride was recorded in anaesthetized animals.4. Pre-treatment of the tongue with 03-5 mg miraculin doubled the summated nerve response to the acids and diminished the response to sucrose by about 10 %. The enhancement lasted for at least an hour and the diminution up to 20 min.5. After miraculin treatment the Spearman's rank correlation coefficient between the order of increased intake of acids and the order of enhancement of the summated nerve response was 0 99. 6. A solution of 0-1 mg miraculin per ml. elicited a weak nerve response. No preference over water for this concentration of miraculin was recorded in the twobottle tests.7. The activity of twenty-nine single taste fibres, selected for their responsiveness to sweetness or acids or both, was recorded after miraculin treatment. Effects were obtained in nine fibres which were similar but more pronounced than those observed in the summated recordings. Before miraculin, these fibres responded better and to a larger variety ofsweeteners (81 %) than the other fibres (40 %). After miraculin, acids elicited on the average 2-3 times more activity than before, while the response to sweeteners was depressed. In twenty fibres no effect of miraculin was observed. These fibres responded to fewer ofthe sweeteners and were more stimulated by the non-sweet stimuli than the first group.The authors' names are in alphabetical order.
Abstract. The intake of six sweeteners was recorded together with their effects on the impulse activity of the chorda tympani proper nerve during their application to the tongue. The sweeteners were: acetosulfam, aspartame, D-tryptophan, glycine, xylitol and thaumatin. They were used at human equi-sweet concentrations. In all species, D-tryptophan was strongly preferred and gave a significant response, while aspartame and thaumatin gave neither a significant behavioral nor a significant neural response. Acetosulfam, glycine and xylitol elicited neural responses, but their behavioral effects differed from a rejection in some species to a preference in others. Miraculin, which has a sweetness inducing effect in man, showed this effect only in the platyrrhinean species and not in the prosimian.
The afferent activity of the facial portion of the chorda‐lingual nerve, the chorda tympani proper, and the glossopharyngeal nerves was recorded during the application of 0.02 % and 0.005 % solutions of Monellin (2times 10‐5 and 5times 10‐6 M) and Thaumatin (10‐5 and 2.1) × 10 ‐6 M) and of 0.5 M sucrose, 0.3 M NaCl and 0.03 M citric acid, representing the three taste qualities sweet, salt and acid. Monellin and Thaumatin, which give a sweet sensation in man, elicited a significant electrophysiological response in the monkey which showed several characteristics that could be related to psychophysical observations in man. In guinea pig and rat little or no response could be recorded.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.