Duodenal and portal glucose changes shown to regulate eating behaviour via brain area modulations - GreenMedInfo Summary

Peripheral and central glucose sensing play a major role in the regulation of food intake. Peripheral sensing occurs at duodenal and portal levels, but the importance of these sensing sites is still controversial. The aim of our study was to compare the respective influence of these sensing pathways on the eating patterns, plasma concentrations of glucose, insulin and GLP-1, as well as brain activity in juvenile pigs. In Experiment 1, we characterized the changes in the microstructure of a 30-min meal in 8 conscious animals after duodenal or portal glucose infusion in comparison to saline infusion. In Experiment 2, glucose, insulin and GLP-1 plasma concentrations were measured during 2h after duodenal or portal glucose infusions in 4 anesthetized animals. In Experiment 3, SPECT brain imaging was performed in 5 anesthetized animals receiving duodenal or portal glucose or saline infusions. Both duodenal and portal glucose decreased the amount of food consumed as well as the ingestion speed, but this effect appeared earlier with the portal infusion. Significant differences of glucose and GLP-1 plasma concentrations between treatments were found at the moment of brain imaging. Both duodenal and portal glucose infusions activated the dorsolateral prefrontal cortex and primary somatosensory cortex. Only duodenal glucose infusion induced the activation of the prepyriform area, orbitofrontal cortex, caudate and putamen, as well as the deactivation of the anterior prefrontal cortex and anterior entorhinal cortex, while only portal glucose infusion induced a significant activation of the insular cortex. We demonstrated that duodenal and portal glucose infusions led to the modulation of brain areas that are known to regulate eating behaviour, which probably explains the decrease of food intake after both stimulations. Though, these stimulation pathways induced specific systemic and central responses suggesting that different brain processing matrices are involved.© 2012 The Authors. Journal of Neuroendocrinology © 2012 Blackwell Publishing Ltd.