Intestinal NAPE-PLD contributes to short-term regulation of food intake via gut-to-brain axis

Abstract

Our objective was to explore the physiological role of the intestinal endocannabinoids in the regulation of appetite upon short-term exposure to high-fat-diet (HFD) and understand the mechanisms responsible for aberrant gut-brain signaling leading to hyperphagia in mice lacking <i>Napepld</i> in the intestinal epithelial cells (IECs). We generated a murine model harboring an inducible NAPE-PLD deletion in IECs (<i>Napepld</i>^ΔIEC). After an overnight fast, we exposed wild-type (WT) and <i>Napepld</i>^ΔIEC mice to different forms of lipid challenge (HFD or gavage), and we compared the modification occurring in the hypothalamus, in the vagus nerve, and at endocrine level 30 and 60 min after the stimulation. <i>Napepld</i>^ΔIEC mice displayed lower hypothalamic levels of <i>N</i>-oleoylethanolamine (OEA) in response to HFD. Lower mRNA expression of anorexigenic <i>Pomc</i> occurred in the hypothalamus of <i>Napepld</i>^ΔIEC mice after lipid challenge. This early hypothalamic alteration was not the consequence of impaired vagal signaling in <i>Napepld</i>^ΔIEC mice. Following lipid administration, WT and <i>Napepld</i>^ΔIEC mice had similar portal levels of glucagon-like peptide-1 (GLP-1) and similar rates of GLP-1 inactivation. Administration of exendin-4, a full agonist of GLP-1 receptor (GLP-1R), prevented the hyperphagia of <i>Napepld</i>^ΔIEC mice upon HFD. We conclude that in response to lipid, <i>Napepld</i>^ΔIEC mice displayed reduced OEA in brain and intestine, suggesting an impairment of the gut-brain axis in this model. We speculated that decreased levels of OEA likely contributes to reduce GLP-1R activation, explaining the observed hyperphagia in this model. Altogether, we elucidated novel physiological mechanisms regarding the gut-brain axis by which intestinal NAPE-PLD regulates appetite rapidly after lipid exposure.