Cooperative enhancement of insulinotropic action of GLP-1 by acetylcholine uncovers paradoxical inhibitory effect of beta cell muscarinic receptor activation on adenylate cyclase activity

JC Miguel, Yasser Abdel-Wahab, BD Green, PCF Mathias, Peter Flatt

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Abstract

The cooperative effect of glucagon-like peptide 1 (GLP-1) and acetylcholine (ACh) was evaluated in a beta cell line model (BRIN BD11). GLP-1 (20 nM) and ACh (100 muM) increased insulin secretion by 24-47%, whereas in combination there was a further 89% enhancement of insulin release. Overnight culture with 100 ng/mL pertussis toxin (PTX) or 10 nM PMA significantly reduced the combined insulinotropic action (P <0.05 and P <0.001, respectively) and the sole stimulatory effects of GLP-1 (PTX treatment; P<0.01) or ACh (PMA treatment; P <0.05). Under control conditions, ACh (50 nM-1 mM) concentration-dependently inhibited by up to 40% (P <0.001) the 10-fold (P <0.001) elevation of cyclic 3',5'-adenosine monophosphate (cAMP) induced by 20 nM GLP-1. The paradoxical inhibitory action of ACh was abolished by PTX pre-treatment, suggesting involvement of G(i) and/or G(o) G protein alpha subunit. Effects of selective muscarinic receptor antagonists on the concentration-dependent insulinotropic actions of ACh (50 nM-1 mM) on 20 nM GLP-1 induced insulin secretion revealed inhibition by rho-FHHSiD (M3 antagonist, P <0.05), stimulation with pirenzepine (M1 antagonist, P <0.001) and no significant effects of either methoctramine (M2 antagonist) or MT-3 (M4 antagonist). Antagonism of M2, M3 and M4 muscarinic receptor effects with methoctramine (3-100 nM), rho-FHHSiD (3-30 nM) or MT-3 (10-300 nM) did not significantly affect the inhibitory action of ACh on GLP-1 stimulated cAMP production. In contrast, M I receptor antagonism with pirenzepine (3-300 nM) resulted in a concentration-dependent decrease in the inhibitory action of ACh on GLP-1 stimulated cAMP production (P <0.001). These data indicate an important functional cooperation between the cholinergic neurotransmitter ACh and the incretin hormone GLP-1 on insulin secretion mediated through the M3 muscarinic receptor subtype. However, the insulinotropic action of ACh was associated with a paradoxical inhibitory effect on GLP-1 stimulated cAMP production, achieved through a novel PTX- and pirenzepine-sensitive M1 muscarinic receptor activated pathway. An imbalance between these pathways may contribute to dysfunctional insulin secretion. (C) 2002 Elsevier Science Inc. All rights reserved.
LanguageEnglish
Pages283-292
JournalBIiochemical Pharmacology
Volume65
Issue number2
Publication statusPublished - Jan 2003

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Glucagon-Like Peptide 1
Muscarinic Receptors
Adenylyl Cyclases
Acetylcholine
Pertussis Toxin
Pirenzepine
Cyclic AMP
Insulin
Cholinergic Agents
Muscarinic M3 Receptors
Muscarinic M1 Receptors
GTP-Binding Protein alpha Subunits
Incretins
Muscarinic Antagonists
Neurotransmitter Agents
Hormones
Cell Line

Cite this

@article{306353e03fb441f9a3bc8cd61b004647,
title = "Cooperative enhancement of insulinotropic action of GLP-1 by acetylcholine uncovers paradoxical inhibitory effect of beta cell muscarinic receptor activation on adenylate cyclase activity",
abstract = "The cooperative effect of glucagon-like peptide 1 (GLP-1) and acetylcholine (ACh) was evaluated in a beta cell line model (BRIN BD11). GLP-1 (20 nM) and ACh (100 muM) increased insulin secretion by 24-47{\%}, whereas in combination there was a further 89{\%} enhancement of insulin release. Overnight culture with 100 ng/mL pertussis toxin (PTX) or 10 nM PMA significantly reduced the combined insulinotropic action (P <0.05 and P <0.001, respectively) and the sole stimulatory effects of GLP-1 (PTX treatment; P<0.01) or ACh (PMA treatment; P <0.05). Under control conditions, ACh (50 nM-1 mM) concentration-dependently inhibited by up to 40{\%} (P <0.001) the 10-fold (P <0.001) elevation of cyclic 3',5'-adenosine monophosphate (cAMP) induced by 20 nM GLP-1. The paradoxical inhibitory action of ACh was abolished by PTX pre-treatment, suggesting involvement of G(i) and/or G(o) G protein alpha subunit. Effects of selective muscarinic receptor antagonists on the concentration-dependent insulinotropic actions of ACh (50 nM-1 mM) on 20 nM GLP-1 induced insulin secretion revealed inhibition by rho-FHHSiD (M3 antagonist, P <0.05), stimulation with pirenzepine (M1 antagonist, P <0.001) and no significant effects of either methoctramine (M2 antagonist) or MT-3 (M4 antagonist). Antagonism of M2, M3 and M4 muscarinic receptor effects with methoctramine (3-100 nM), rho-FHHSiD (3-30 nM) or MT-3 (10-300 nM) did not significantly affect the inhibitory action of ACh on GLP-1 stimulated cAMP production. In contrast, M I receptor antagonism with pirenzepine (3-300 nM) resulted in a concentration-dependent decrease in the inhibitory action of ACh on GLP-1 stimulated cAMP production (P <0.001). These data indicate an important functional cooperation between the cholinergic neurotransmitter ACh and the incretin hormone GLP-1 on insulin secretion mediated through the M3 muscarinic receptor subtype. However, the insulinotropic action of ACh was associated with a paradoxical inhibitory effect on GLP-1 stimulated cAMP production, achieved through a novel PTX- and pirenzepine-sensitive M1 muscarinic receptor activated pathway. An imbalance between these pathways may contribute to dysfunctional insulin secretion. (C) 2002 Elsevier Science Inc. All rights reserved.",
author = "JC Miguel and Yasser Abdel-Wahab and BD Green and PCF Mathias and Peter Flatt",
year = "2003",
month = "1",
language = "English",
volume = "65",
pages = "283--292",
number = "2",

}

TY - JOUR

T1 - Cooperative enhancement of insulinotropic action of GLP-1 by acetylcholine uncovers paradoxical inhibitory effect of beta cell muscarinic receptor activation on adenylate cyclase activity

AU - Miguel, JC

AU - Abdel-Wahab, Yasser

AU - Green, BD

AU - Mathias, PCF

AU - Flatt, Peter

PY - 2003/1

Y1 - 2003/1

N2 - The cooperative effect of glucagon-like peptide 1 (GLP-1) and acetylcholine (ACh) was evaluated in a beta cell line model (BRIN BD11). GLP-1 (20 nM) and ACh (100 muM) increased insulin secretion by 24-47%, whereas in combination there was a further 89% enhancement of insulin release. Overnight culture with 100 ng/mL pertussis toxin (PTX) or 10 nM PMA significantly reduced the combined insulinotropic action (P <0.05 and P <0.001, respectively) and the sole stimulatory effects of GLP-1 (PTX treatment; P<0.01) or ACh (PMA treatment; P <0.05). Under control conditions, ACh (50 nM-1 mM) concentration-dependently inhibited by up to 40% (P <0.001) the 10-fold (P <0.001) elevation of cyclic 3',5'-adenosine monophosphate (cAMP) induced by 20 nM GLP-1. The paradoxical inhibitory action of ACh was abolished by PTX pre-treatment, suggesting involvement of G(i) and/or G(o) G protein alpha subunit. Effects of selective muscarinic receptor antagonists on the concentration-dependent insulinotropic actions of ACh (50 nM-1 mM) on 20 nM GLP-1 induced insulin secretion revealed inhibition by rho-FHHSiD (M3 antagonist, P <0.05), stimulation with pirenzepine (M1 antagonist, P <0.001) and no significant effects of either methoctramine (M2 antagonist) or MT-3 (M4 antagonist). Antagonism of M2, M3 and M4 muscarinic receptor effects with methoctramine (3-100 nM), rho-FHHSiD (3-30 nM) or MT-3 (10-300 nM) did not significantly affect the inhibitory action of ACh on GLP-1 stimulated cAMP production. In contrast, M I receptor antagonism with pirenzepine (3-300 nM) resulted in a concentration-dependent decrease in the inhibitory action of ACh on GLP-1 stimulated cAMP production (P <0.001). These data indicate an important functional cooperation between the cholinergic neurotransmitter ACh and the incretin hormone GLP-1 on insulin secretion mediated through the M3 muscarinic receptor subtype. However, the insulinotropic action of ACh was associated with a paradoxical inhibitory effect on GLP-1 stimulated cAMP production, achieved through a novel PTX- and pirenzepine-sensitive M1 muscarinic receptor activated pathway. An imbalance between these pathways may contribute to dysfunctional insulin secretion. (C) 2002 Elsevier Science Inc. All rights reserved.

AB - The cooperative effect of glucagon-like peptide 1 (GLP-1) and acetylcholine (ACh) was evaluated in a beta cell line model (BRIN BD11). GLP-1 (20 nM) and ACh (100 muM) increased insulin secretion by 24-47%, whereas in combination there was a further 89% enhancement of insulin release. Overnight culture with 100 ng/mL pertussis toxin (PTX) or 10 nM PMA significantly reduced the combined insulinotropic action (P <0.05 and P <0.001, respectively) and the sole stimulatory effects of GLP-1 (PTX treatment; P<0.01) or ACh (PMA treatment; P <0.05). Under control conditions, ACh (50 nM-1 mM) concentration-dependently inhibited by up to 40% (P <0.001) the 10-fold (P <0.001) elevation of cyclic 3',5'-adenosine monophosphate (cAMP) induced by 20 nM GLP-1. The paradoxical inhibitory action of ACh was abolished by PTX pre-treatment, suggesting involvement of G(i) and/or G(o) G protein alpha subunit. Effects of selective muscarinic receptor antagonists on the concentration-dependent insulinotropic actions of ACh (50 nM-1 mM) on 20 nM GLP-1 induced insulin secretion revealed inhibition by rho-FHHSiD (M3 antagonist, P <0.05), stimulation with pirenzepine (M1 antagonist, P <0.001) and no significant effects of either methoctramine (M2 antagonist) or MT-3 (M4 antagonist). Antagonism of M2, M3 and M4 muscarinic receptor effects with methoctramine (3-100 nM), rho-FHHSiD (3-30 nM) or MT-3 (10-300 nM) did not significantly affect the inhibitory action of ACh on GLP-1 stimulated cAMP production. In contrast, M I receptor antagonism with pirenzepine (3-300 nM) resulted in a concentration-dependent decrease in the inhibitory action of ACh on GLP-1 stimulated cAMP production (P <0.001). These data indicate an important functional cooperation between the cholinergic neurotransmitter ACh and the incretin hormone GLP-1 on insulin secretion mediated through the M3 muscarinic receptor subtype. However, the insulinotropic action of ACh was associated with a paradoxical inhibitory effect on GLP-1 stimulated cAMP production, achieved through a novel PTX- and pirenzepine-sensitive M1 muscarinic receptor activated pathway. An imbalance between these pathways may contribute to dysfunctional insulin secretion. (C) 2002 Elsevier Science Inc. All rights reserved.

M3 - Article

VL - 65

SP - 283

EP - 292

IS - 2

ER -