Regional differences in nutrient-induced secretion of gut serotonin.
Enterochromaffin (EC) cells located in the gastrointestinal (GI) tract provide the vast majority of serotonin (5-HT) in the body and constitute half of all enteroendocrine cells. EC cells respond to an array of stimuli, including various ingested nutrients. Ensuing 5-HT release from these cells plays a diverse role in regulating gut motility as well as other important responses to nutrient ingestion such as glucose absorption and fluid balance. Recent data also highlight the role of peripheral 5-HT in various pathways related to metabolic control. Details related to the manner by which EC cells respond to ingested nutrients are scarce and as that the nutrient environment changes along the length of the gut, it is unknown whether the response of EC cells to nutrients is dependent on their GI location. The aim of the present study was to identify whether regional differences in nutrient sensing capability exist in mouse EC cells. We isolated mouse EC cells from duodenum and colon to demonstrate differential responses to sugars depending on location. Measurements of intracellular calcium concentration and 5-HT secretion demonstrated that colonic EC cells are more sensitive to glucose, while duodenal EC cells are more sensitive to fructose and sucrose. Short-chain fatty acids (SCFAs), which are predominantly synthesized by intestinal bacteria, have been previously associated with an increase in circulating 5-HT; however, we find that SCFAs do not acutely stimulate EC cell 5-HT release. Thus, we highlight that EC cell physiology is dictated by regional location within the GI tract, and identify differences in the regional responsiveness of EC cells to dietary sugars.
Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia.
Alyce M
AM
Martin
Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia.
Amanda L
AL
Lumsden
South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.|Adelaide Medical School, University of Adelaide, Adelaide, Australia.
Richard L
RL
Young
Department of Anatomy and Histology and Centre for Neuroscience, Flinders University, Adelaide, Australia.|Adelaide Medical School, University of Adelaide, Adelaide, Australia.
Claire F
CF
Jessup
Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia.
Nick J
NJ
Spencer
Department of Human Physiology and Centre for Neuroscience, Flinders University, Adelaide, Australia damien.keating@flinders.edu.au.|South Australian Health and Medical Research Institute (SAHMRI), Adelaide, Australia.
Damien J
DJ
Keating
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D004759:Enterochromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000494:pharmacology; D005632:Fructose / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012701:Serotonin / Q000378:metabolism*; D013395:Sucrose / Q000494:pharmacology
D005232:Fatty Acids, Volatile; D005632:Fructose; D012701:Serotonin; D013395:Sucrose; D002118:Calcium
Enterochromaffin; nutrients; serotonin