Vagal afferent neurons in high fat diet-induced obesity; intestinal microflora, gut inflammation and cholecystokinin

The vagal afferent pathway is the major neural pathway by which information about ingested nutrients reaches the CNS and influences both GI function and feeding behavior. Vagal afferent neurons (VAN) express receptors for many of the regulatory peptides and molecules released from the intestinal wall, pancreas, and adipocytes that influence GI function, glucose homeostasis, and regulate food intake and body weight. As such, they play a critical role in both physiology and pathophysiology, such as obesity, where there is evidence that vagal afferent function is altered. This review will summarize recent findings on changes in vagal afferent function in response to ingestion of high fat diets and explore the hypothesis that changes in gut microbiota and integrity of the epithelium may not only be important in inducing these changes but may be the initial events that lead to dysregulation of food intake and body weight in response to high fat, high energy diets.

Research Highlights
► CCK has short and long terms effects on vagal afferent neurons.
► Vagal afferent neurons can express either a “fed” or “fasted” phenotype.
► The phenotypic switch of vagal afferent neurons may be absent in DIO.
► High fat diets change gut microbiota, induces inflammation and increases permeability.
► The gut may be a source of inflammation in obesity.