Abstract
Gastrointestinal vagal afferents (VAs) play an important role in food intake regulation, providing the brain with information on the amount and nutrient composition of a meal. This is processed, eventually leading to meal termination. The response of gastric VAs, to food-related stimuli, is under circadian control and fluctuates depending on the time of day. These rhythms are highly correlated with meal size, with a nadir in VA sensitivity and increase in meal size during the dark phase and a peak in sensitivity and decrease in meal size during the light phase in mice. These rhythms are disrupted in diet-induced obesity and simulated shift work conditions and associated with disrupted food intake patterns. In diet-induced obesity the dampened responses during the light phase are not simply reversed by reverting back to a normal diet. However, time restricted feeding prevents loss of diurnal rhythms in VA signalling in high fat diet-fed mice and, therefore, provides a potential strategy to reset diurnal rhythms in VA signalling to a pre-obese phenotype. This review discusses the role of the circadian system in the regulation of gastrointestinal VA signals and the impact of factors, such as diet-induced obesity and shift work, on these rhythms.
Highlights
Gastrointestinal vagal afferents (VAs) play an important role in food intake regulation, providing the brain with information on the amount and nutrient composition of a meal
Gastric vagal afferents (VAs) display diurnal rhythms in their response to food related stimuli [2]. These rhythms are inversely associated with meal size and meal frequency and stomach content [2,3], such that in mice the nadir in gastric VA sensitivity during the dark phase is associated with an increase meal size and meal frequency, whereas the peak in sensitivity during the light phase is associated with reduced meal size and meal frequency [3]
VAs be classified, based sponse to various stimuli, into three main main groups, namely mechano, chemoand thertheir response to various stimuli, into three groups, namely mechano, chemoand moreceptors, all all with specific roles this review review thermoreceptors, with specific rolesiningastrointestinal gastrointestinalphysiology, physiology, this willfocus focuson onmechanomechano-and andchemoreceptors chemoreceptorsdue dueto totheir theirknown knownor orsuspected suspectedrole roleininfood food will intake intakeregulation regulation[7]
Summary
Gastrointestinal role in in food intake regulation [6],[6], signalling to to the hindbrain the arrival, amount and chemical composition of a meal. Using a similar approach a distinct population of tension-mucosal receptors could not be identified in the mouse [11] This is possibly a consequence of the thinness of the oesophageal tissue in the mice, where low intensity mucosal stroking with von Frey hairs (e.g., 10 mg) can stretch the underlying muscular layer making it impossible to distinguish between tension and tensionmucosal receptors [11]. Soon after their identification a similar subpopulation of colonic splanchnic and pelvic afferents, termed mucosal-muscular receptors, were identified in mice [23]. There is evidence that a single dorsal root ganglia neuron can receive input from a number of endings within the gut wall [25,26], including the mucosa, myenteric ganglia and circular muscle, the location of vagal tension-mucosal afferents remains to be determined and it is possible that a single ending in the subepithelial plexus is responsive to both stretch and mucosal stroking [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
