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Secreted effectors of the innate mucosal barrier
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Michael A. McGuckin, Andre J. Ouellette, Gary D. Wu
Enteroendocrine cells account for approximately 1% of intestinal epithelial cells with about 15 different subtypes that express various enteric hormones. Downstream of the Notch–Math1 pathway is the bHLH transcription factor Neurogenin 3, which is required for development of the enteroendocrine cell lineage. Downstream of Neurogenin 3, additional bHLH and homeodomain transcription factors have been shown to be important for the development of specific enteroendocrine subtypes. Another relatively infrequent differentiated epithelial cell type is tuft cells that have a unique morphology with long and thick microvilli projecting into the lumen. These cells share morphologic and functional features with taste-receptor cells that express the cation channel Trpm5 and play a role in type 2 immune responses initiated by protozoa and helminth parasite infections, where they are the source of IL-25.
Chemosensation
Published in Emily Crews Splane, Neil E. Rowland, Anaya Mitra, Psychology of Eating, 2019
Emily Crews Splane, Neil E. Rowland, Anaya Mitra
Because they respond (i.e., secrete hormones) in response to food-related stimuli, these enteroendocrine cells must also have receptor(s) to recognize food. Many of the sensory mechanisms that accomplish this do so via receptors that are similar or identical to those in taste buds, except that we are not consciously aware of enteric sensing (Mayer, 2011). The signals to the brain are of two main types: Action potentials in sensory afferents of the vagus nerve and specific hormones that are released into the blood stream (thence to the brain) as a result of specific enteroendocrine cell stimulation. For completeness, we note there are also receptors in the food tube for stimuli such as toxins and physical stretching, and this information goes to the brain via spinal afferent neurons. Primary vagal afferents first synapse in the brain in the rostral NST. The linear organization of the NST from gut (back) to mouth (front) reinforces the idea that the sensory surface of the gut is best viewed as a continuation of the mouth.
Non Adrenergic, Noncholinergic Innervation of Gastrointestinal Vessels
Published in Geoffrey Burnstock, Susan G. Griffith, Nonadrenergic Innervation of Blood Vessels, 2019
Annica B. Dahlström, Ola Nilsson, Ove Lundgren, Håkan Ahlman
Somatostatin (SOM) is a 14-amino acid polypeptide originally isolated by Krulich et al.139 as a substance which inhibits the release of growth hormone from the pituitary gland.140 It was later purified from bovine hypothalamus and subsequently SOM was also found to be located in nervous tissue in the gastrointestinal tract.50,141-144 A significant proportion is also present in enteroendocrine cells throughout the gastrointestinal tract.142,145,146
Gut microbiota-motility interregulation: insights from in vivo, ex vivo and in silico studies
Published in Gut Microbes, 2022
Barbora Waclawiková, Agnese Codutti, Karen Alim, Sahar El Aidy
Gut hormones are released from specialized intestinal epithelial cells, enteroendocrine cells, in response to meal-related stimuli. Subsequently, these gut hormones exert actions ranging from the local control of gut motility, to the regulation of glucose homeostasis, and food intake.68 Gastrointestinal motility is modulated by gut hormones during both the interdigestive (i.e. between meals; motilin and ghrelin), and postprandial (i.e. after meals; cholecystokinin (CCK), glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and peptide YY (PYY)) periods.69 GLP-1, and PYY are key mediators of the shift from an interdigestive to a postprandial gastrointestinal motor pattern.69 Moreover, the gut hormones CCK, GLP-1, and PYY control blood nutrient levels by modulating digestion and absorption, as slowing either of these steps reduces the rate at which ingested nutrients enter the circulation.68
Evaluation of plasma cholecystokinin levels and gallbladder functions in hyperemesis gravidarum: a prospective cohort study
Published in Journal of Obstetrics and Gynaecology, 2022
Müge Keskin, Tuba Çandar, Mehmet Çoban, Kaan Gökçe Ataç, Aslı Yarci Gürsoy, Gamze Sinem Çağlar
Cholecystokinin (CCK) is a gastrointestinal hormone and a neurotransmitter peptide expressed in the brain. It is secreted by enteroendocrine cells (I cells) located in the mucosa of the duodenum, jejunum and proximal ileum and by specialised neurons in the myenteric plexus and brain. CCK stimulates contraction of the gallbladder (GB) and relaxation of the sphincter of Oddi (Liddle 2000; Wang et al. 2017). Pregnancy induces morphological and functional biliary tract changes, and both animal and human studies have reported elevated CCK levels during pregnancy (Rådberg et al. 1987; Frick et al. 1990). Even if the pathophysiology has not yet been clarified, the proposed mechanisms depend on either enhanced secretion or reduced elimination of CCK (Rådberg et al. 1987). Concerning the physiological implications of enhanced CCK levels, GB contractility does not increase during pregnancy (Rådberg et al. 1987; Portincasa et al. 2003; Housset et al. 2016), possibly because of reduced GB sensitivity to CCK (Kline and Karpinski 2005) with the decrease in the CCK-A receptor expression or impaired signalling through this receptor during pregnancy (Ladyman et al. 2011).
Spatiotemporal organization of enteroendocrine peptide expression in Drosophila
Published in Journal of Neurogenetics, 2021
Sooin Jang, Ji Chen, Jaekyun Choi, Seung Yeon Lim, Hyejin Song, Hyungjun Choi, Hyung Wook Kwon, Min Sung Choi, Jae Young Kwon
As we and others have shown, in this study and elsewhere, the enteroendocrine cells of the Drosophila midgut show extensive variations in peptide co-expression patterns (Guo et al., 2019). Targeting and manipulating the activity of specific types of enteroendocrine cells would be an extremely useful tool in examining the specific functions of each subset. Thousands of GAL4 lines expressed in distinct subsets of cells in the adult fly brain have been generated, with the initial purpose of studying the fly nervous system (Pfeiffer et al., 2008). Recently, GAL4 and split-GAL4 drivers that label intestinal cells in specific spatial and functional regions of the Drosophila gastrointestinal tract have been reported (Ariyapala et al., 2020; Lim et al., 2020). Co-staining with the antisera used in this study and these GAL4 and split-GAL4 drivers could define the enteroendocrine cells based on which peptides are produced, and lead to the development of tools for manipulating specific functional groups of enteroendocrine cells.