Nutropioids Regulate Gut-Brain Circuitry Controlling Food Intake

The modulation of hunger sensations by the mu-opioid receptor (MOR) present in the brain is an established fact. That MORs expressed in the periphery could have a similar role was outstanding. Using portal infusions of agonists and/or antagonists of MOR in conscious rodents, we have shown that MORs present in the walls of the portal vein nervous system control a gut-brain circuit of induction of intestinal gluconeogenesis (IGN), a function controlling hunger sensations. Then, we have shown that peptides and proteins promote a MOR-dependent induction of IGN. Peptides have no effect in mice knockout for MOR. MOR-KO mice are also insensitive to satiety induced by protein-enriched diets. In addition, portal infusions of MOR modulators have no effect on food intake in mice deficient for IGN. Thus, the regulation by portal MORs and peptides of a gut-brain neural circuit of induction of IGN is a causal link in the phenomenon of satiety induced by dietary protein. (C) 2014 S. Karger AG, Basel