Role of sensory input in the control of food intake.
The role of the sensory input involved in the control of the food intake is briefly reviewed. Signals from mouth and throat, as well as signals from the gastrointestinal tract and the liver, are necessary but none of them are sufficient to induce satiation. The oral cues initiated by the food intake have a dual action on the feeding behavior. They first stimulate the intake in the hungry subjects. They sustain it until the amount of food ingested reaches the level necessary to equilibrate the energy balance. Finally, they participate, with the sensory input from the gastrointestinal tract, in the process inhibiting the food intake. The hedonic hypothesis of the food intake control is an attempt to explain this dual action of the peripheral alimentary analyzer in this homeostatic behavior. It was proposed that the alimentary pleasure or displeasure brought by alimentary stimuli acts as a drive for the food intake behavior. Indeed, in normal human subjects, the affective component of the alimentary sensations is not constant, but depends on the subjects' internal state. From pleasant, in subjects requiring some energy supply for long-term or short-term energy regulation, alimentary sensations become less pleasant or unpleasant in satiated subjects or in overfed subjects. This change of the affective component of a peripheral sensation, according to the internal state, was called: negative alimentary alliesthesia. Alliesthesia is a specific and reproducible phenomenon. It has been shown that the internal signal which induces negative alimentary alliesthesia depends on the carbohydrate concentration into the gastrointestinal tract, mainly into the duodenum. This signal may provide information related to the energy content of the ingested food. The neural or humoral nature of the transmission of this information from the gut to the brain is discussed. A neural link possibly involves the enteric glucidoreceptors recently described. In conclusion, the validity and the limits of the hedonic hypothesis of the food intake is briefly discussed.
D000339:Affect; D000818:Animals; D004064:Digestive System / Q000294:innervation*; D004386:Duodenum / Q000294:innervation; D004734:Energy Metabolism; D005247:Feeding Behavior / Q000502:physiology*; D006706:Homeostasis; D006801:Humans; D008099:Liver / Q000294:innervation; D009055:Mouth / Q000294:innervation; D009475:Neurons, Afferent / Q000502:physiology; D010614:Pharynx / Q000294:innervation; D011168:Portal System / Q000294:innervation; D051381:Rats; D012527:Satiation / Q000502:physiology*; D013649:Taste / Q000502:physiology; D013997:Time Factors