Table 1.

Comparison of 6 gut hormones by stimuli, secretory cells, biogenic factors, and functions

	Stimuli	Secretory cells	Biogenic factors (TF/enzyme)	Function (local)	Function (systemic)
GLP-1	−Glucose −LCFAs −SCFAs −Bile acids −Other gut hormones (CCK, GIP, and serotonin) −Neurotransmitters [pituitary adenylate cyclase–activating protein (PACAP), calcitonin gene–related peptide (CGRP), and bombesin] (Reimann et al., 2012) −Inflammation (LPS, IL-6)	L-cell of EEC in distal ileum, proximal colon	PDX1 NEUROD1/prohormone convertase 1/3	−Slowing gastric emptying −Regulating the function of T cells	(Brain) Reducing appetite, satiety, and inhibition of food intake (Pancreas) Enhancing insulin secretion
PYY	−LCFAs −SCFAs −Amino acids, peptides −Bile acids −Neurotransmitters (PACAP) −(Reimann et al., 2012) −Other gut hormones (GLP, CCK)	L-cell of EEC in ileum, colon	Prohormone convertase 1/3	−Slowing gastric emptying −Slowing intestinal transit	(Brain) Reducing appetite, satiety, and inhibition of food intake (Pancreas) Inhibition of pancreatic enzyme secretion, enhancing insulin secretion (Gallbladder) Inhibiting gallbladder contraction (Adriaenssens et al., 2018)
CCK	−LCFAs(+) −MCFAs(−) −SCFAs(+) −Aromatic amino acids −LPS −Neurotransmitters (PACAP) −(Reimann et al., 2012)	I-cell of EEC in duodenum, jejunum	Prohormone convertase 1/3	−Promoting intestinal enzyme secretion −Regulating the function of CD4 T cells	(Brain) Reducing appetite, satiety, and acute suppression of food intake (Pancreas) Promoting pancreatic enzyme secretion (Gallbladder) Stimulating gallbladder contraction
Serotonin	−Glucose −Fatty acids −Stretching of the gut wall −Vagal nerve stimulation −Inflammation (IL-13) −Alarmin (IL-33)	ECs in duodenum, jejunum, ileum, and colon	LMX1A (Gross et al., 2016)/TPH1, and AADC	−Promoting epithelial growth, enteric neurogenesis −Regulating of peristalsis −Stimulating of digestive fluids −Sensation of visceral pain	(Brain) Reducing appetite (Liver) Increasing glucose production (Adipose tissue) Increasing lipid mobilization
Somatostatin	−Free fatty acids (Gribble and Reimann, 2016) −MCFAs −Acidity −Other gut hormones	D-cell of EEC in gastric fundus, antrum, duodenum, and jejunum	PDX1/prohormone convertase 1	−Inhibition of other gut hormones −Reducing gastric acid and digestive enzymes secretion −Slowing gastric emptying	(Brain) Inhibition of GH and TSH secretion (Nerve) Inhibition of neurotransmitter release (Pancreas) Inhibition of insulin and glucagon secretion (Rorsman and Huising, 2018)
Glucocorticoids	−Inflammation (LPS, TNF) (Bayrer et al., 2018; Noti et al., 2010b) −Tissue damage? −Stress?	IECs (intestinal crypt cells) in ileum, colon	LRH-1/CYP11A1, CYP11B1, and 11β-HSD1	−Inhibition of inflammation	Unknown

GLP-1, glucagon-like peptide 1; LCFAs, long-chain fatty acids; SCFAs, short-chain fatty acids; CCK, cholecystokinin; GIP, glucose-dependent insulinotropic polypeptide; LPS, lipopolysaccharides; IL, interleukin; EEC, enteroendocrine cell; TF, transcription factor; PDX-1, pancreatic and duodenal homeobox 1; NEUROD1, neurogenic differentiation 1; PYY, peptide YY; MCFAs, medium-chain fatty acids; ECs, enterochromaffin cells; GH, growth hormone; TSH, thyroid-stimulating hormone; TNF, tumor necrosis factor; IECs, intestinal epithelial cells; LRH-1, liver receptor homolog-1; CYP, cytochrome P450 family; 11β-HSD1, 11β-hydroxysteroid dehydrogenase type 1.