The impact of short chain fatty acids on GLP-1 and PYY secretion from the isolated perfused rat colon

TY - JOUR

T1 - The impact of short chain fatty acids on GLP-1 and PYY secretion from the isolated perfused rat colon

AU - Christiansen, Charlotte Bayer

AU - Gabe, Maria Buur Nordskov

AU - Svendsen, Berit

AU - Dragsted, Lars Ove

AU - Rosenkilde, Mette

AU - Holst, Jens Juul

N1 - CURIS 2018 NEXS 262

PY - 2018/7

Y1 - 2018/7

N2 - The colonic epithelium harbors a large number of endocrine cells, but little is known about the endocrine functions of the colon. However, the high density of glucagon like peptide-1 (GLP-1)-and peptide-YY (PYY)-secreting L cells is of great interest because of the potential antidiabetic and antiobesity effects of GLP-1 and PYY. Short-chain fatty acids (SCFAs) produced by local bacterial fermentation are suggested to activate the colonic free fatty acid receptors FFAR2 (GPR43) and FFAR3 (GPR41), stimulating the colonic L cells. We used the isolated perfused rat colon as a model of colonic endocrine secretion and studied the effects of the predominant SCFAs formed: acetate, propionate, and butyrate. We show that luminal and especially vascular infusion of acetate and butyrate significantly increases colonic GLP-1 secretion, and to a minor extent also PYY secretion, but only after enhancement of intracellular cAMP. Propionate neither affected GLP-1 nor PYY secretion whether administered luminally or vascularly. A FFAR2-and FFAR3–specific agonist [(S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butamide (CFMB)/AR420626] had no effect on colonic GLP-1 output, and a FFAR3 antagonist (AR399519) did not decrease the SCFA-induced GLP-1 response. However, the voltage-gated Ca2+-channel blocker nifedipine, the KATP-channel opener diazoxide, and the ATP synthesis inhibitor 2,4-dinitrophenol completely abolished the responses. FFAR2 receptor studies confirmed low-potent partial agonism of acetate, propionate, and butyrate, compared with CFMB, which is a full agonist with ~750-fold higher potency than the SCFAs. In conclusion, SCFAs may increase colonic GLP-1/PYY secretion, but FFAR2/FFAR3 do not seem to be involved. Rather, SCFAs are metabolized and appear to function as a colonocyte energy source. NEW & NOTEWORTHY By the use of in situ isolated perfused rat colon we show that short-chain fatty acids (SCFAs) primarily are used as a colonocyte energy source in the rat, subsequently triggering glucagon like peptide-1 (GLP-1) secretion independent of the free fatty acid receptors FFAR2 and FFAR3. Opposite many previous studies on SCFAs and FFAR2/FFAR3 and GLP-1 secretion, this experimental model allows investigation of the physiological interactions between luminal nutrients and secretion from cells whose function depend critically on their blood supply as well as nerve and paracrine interactions.

AB - The colonic epithelium harbors a large number of endocrine cells, but little is known about the endocrine functions of the colon. However, the high density of glucagon like peptide-1 (GLP-1)-and peptide-YY (PYY)-secreting L cells is of great interest because of the potential antidiabetic and antiobesity effects of GLP-1 and PYY. Short-chain fatty acids (SCFAs) produced by local bacterial fermentation are suggested to activate the colonic free fatty acid receptors FFAR2 (GPR43) and FFAR3 (GPR41), stimulating the colonic L cells. We used the isolated perfused rat colon as a model of colonic endocrine secretion and studied the effects of the predominant SCFAs formed: acetate, propionate, and butyrate. We show that luminal and especially vascular infusion of acetate and butyrate significantly increases colonic GLP-1 secretion, and to a minor extent also PYY secretion, but only after enhancement of intracellular cAMP. Propionate neither affected GLP-1 nor PYY secretion whether administered luminally or vascularly. A FFAR2-and FFAR3–specific agonist [(S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butamide (CFMB)/AR420626] had no effect on colonic GLP-1 output, and a FFAR3 antagonist (AR399519) did not decrease the SCFA-induced GLP-1 response. However, the voltage-gated Ca2+-channel blocker nifedipine, the KATP-channel opener diazoxide, and the ATP synthesis inhibitor 2,4-dinitrophenol completely abolished the responses. FFAR2 receptor studies confirmed low-potent partial agonism of acetate, propionate, and butyrate, compared with CFMB, which is a full agonist with ~750-fold higher potency than the SCFAs. In conclusion, SCFAs may increase colonic GLP-1/PYY secretion, but FFAR2/FFAR3 do not seem to be involved. Rather, SCFAs are metabolized and appear to function as a colonocyte energy source. NEW & NOTEWORTHY By the use of in situ isolated perfused rat colon we show that short-chain fatty acids (SCFAs) primarily are used as a colonocyte energy source in the rat, subsequently triggering glucagon like peptide-1 (GLP-1) secretion independent of the free fatty acid receptors FFAR2 and FFAR3. Opposite many previous studies on SCFAs and FFAR2/FFAR3 and GLP-1 secretion, this experimental model allows investigation of the physiological interactions between luminal nutrients and secretion from cells whose function depend critically on their blood supply as well as nerve and paracrine interactions.

KW - Faculty of Science

KW - Colon

KW - GLP-1

KW - GPCRs

KW - PYY

KW - Short chain fatty acids

U2 - 10.1152/ajpgi.00346.2017

DO - 10.1152/ajpgi.00346.2017

M3 - Journal article

C2 - 29494208

SN - 0193-1857

VL - 315

SP - G53-G65

JO - American Journal of Physiology: Gastrointestinal and Liver Physiology

JF - American Journal of Physiology: Gastrointestinal and Liver Physiology

IS - 1

ER -