Experimental study of the internal signal of alliesthesia induced by sweet molecules in rats.

To identify the preabsorptive signal that arouses alliesthesia, we compared the effects of five sweet molecules: glucose (3 g.5 ml-1), cyclamate (0.280 g.5 ml-1), saccharin (0.016 g.5 ml-1), aspartame (0.020 g.5 ml-1), and mannitol (3 g.5 ml-1) on the intestive aversive responses of rats. In Experiment 1, the sweet stimuli were adjusted to taste similarly sweet, and they were administered orally; they aroused similar ingestive responses. In Experiment 2, an isovolumetric load of each of the five molecules was administered in the stomach and its influence on ingestive/aversive response aroused by oral sucrose was recorded. Negative alliesthesia was obtained after gastric loads of glucose and mannitol, but not after gastric loads of cyclamate, saccharin, and aspartame.