Enteroendocrine cells are specialized
cells of the
gastrointestinal tract and
pancreas with
endocrine function. They produce
gastrointestinal hormones or peptides in response to various stimuli and release them into the bloodstream for systemic effect, diffuse them as
local messengers, or transmit them to the
enteric nervous system to activate nervous responses.[1][2] Enteroendocrine cells of the intestine are the most numerous endocrine cells of the body.[3][4][5] They constitute an enteric endocrine system as a subset of the
endocrine system just as the
enteric nervous system is a subset of the
nervous system.[6] In a sense they are known to act as
chemoreceptors, initiating digestive actions and detecting harmful substances and initiating protective responses.[7][8] Enteroendocrine cells are located in the stomach, in the intestine and in the pancreas. Microbiota play key roles in the intestinal immune and metabolic responses in these enteroendocrine cells via their fermentation product (
short chain fatty acid),
acetate.[9]
Intestinal enteroendocrine cells
Intestinal enteroendocrine cells are not clustered together but spread as single cells throughout the intestinal tract.[7]
Located in a increasing manner throughout the
small intestine, with the highest levels found in the in
ileum,[19] N cells release
neurotensin, and control smooth muscle contraction.[20]
S cells secrete
secretin mostly from the
duodenum, but also in decreasing amounts throughout the rest of the
small intestine,[21] and stimulate exocrine pancreatic secretion.[16]
Pancreatic enteroendocrine cells are located in the
islets of Langerhans and produce most importantly the hormones
insulin and
glucagon. The
autonomous nervous system strongly regulates their secretion, with parasympathetic stimulation stimulating insulin secretion and inhibiting glucagon secretion and sympathetic stimulation having opposite effect.[25]
Rare and slow growing
carcinoid and non-carcinoid tumors develop from these cells. When a tumor arises it has the capacity to secrete large volumes of hormones.[2][26]
History
The very discovery of hormones occurred during studies of how the digestive system regulates its activities, as explained at Secretin § Discovery.
^
abSolcia E, Capella C, Buffa R, Usellini L, Fiocca R, Frigerio B, Tenti P, Sessa F (1981). "The diffuse endocrine-paracrine system of the gut in health and disease: ultrastructural features". Scandinavian Journal of Gastroenterology. Supplement. 70: 25–36.
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^Sternini C (February 2007). "Taste receptors in the gastrointestinal tract. IV. Functional implications of bitter taste receptors in gastrointestinal chemosensing". American Journal of Physiology. Gastrointestinal and Liver Physiology. 292 (2): G457–61.
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^Friis-Hansen L, Sundler F, Li Y, Gillespie PJ, Saunders TL, Greenson JK, Owyang C, Rehfeld JF, Samuelson LC (March 1998). "Impaired gastric acid secretion in gastrin-deficient mice". The American Journal of Physiology. 274 (3 Pt 1): G561–8.
doi:
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PMID9530158.
^Ormsbee HS, Fondacaro JD (March 1985). "Action of serotonin on the gastrointestinal tract". Proceedings of the Society for Experimental Biology and Medicine. 178 (3): 333–8.
doi:
10.3181/00379727-178-42016.
PMID3919396.
S2CID34829257.
^Kitabgi P, Freychet P (August 1978). "Effects of neurotensin on isolated intestinal smooth muscles". European Journal of Pharmacology. 50 (4): 349–57.
doi:
10.1016/0014-2999(78)90140-1.
PMID699961.
^Zverkov IV, Vinogradov VA, Smagin VG (October 1983). "[Endorphin-containing cells in the gastric antral mucosa in duodenal ulcer]". Biulleten' Eksperimental'noi Biologii I Meditsiny. 96 (10): 32–4.
PMID6194833.
^Kiba T (August 2004). "Relationships between the autonomic nervous system and the pancreas including regulation of regeneration and apoptosis: recent developments". Pancreas. 29 (2): e51–8.
doi:
10.1097/00006676-200408000-00019.
PMID15257115.
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