TY - JOUR
T1 - Lithocholylcholine, a bile acid/acetylcholine hybrid, is a muscarinic receptor antagonist
AU - Cheng, Kunrong
AU - Khurana, Sandeep
AU - Chen, Ying
AU - Kennedy, Richard H.
AU - Zimniak, Piotr
AU - Raufman, Jean Pierre
PY - 2002/10
Y1 - 2002/10
N2 - Previous work from our laboratory indicates that bile acids, specifically lithocholic acid conjugates, interact with muscarinic receptors on gastric chief cells. Structural similarities between acetylcholine and lithocholyltaurine suggest a potential molecular basis for their interaction with the same receptor. We synthesized a hybrid molecule consisting of the steroid nucleus of lithocholyltaurine and the choline moiety of acetylcholine. The new molecule, lithocholylcholine, is hydrolyzed by acetylcholinesterase. Lithocholylcholine inhibited binding of a cholinergic radioligand to Chinese hamster ovary cells expressing each of the five muscarinic receptor subtypes. The binding affinities (K1; micromolar) of lithocholylcholine for these receptors were: M3 (1.0) > M1 (2.7) > M2 (4.1) = M4 (4.9) > M5 (6.2). Lithocholylcholine inhibited intracellular signaling pathways mediated by interaction with M1, M2, and M3 muscarinic receptors. Regarding M3 receptors, lithocholylcholine was 10-fold more potent than lithocholyltaurine in terms of binding affinity and inhibition of acetylcholine-induced increases in inositol phosphate formation and mitogen-activated protein kinase phosphorylation. In a functional assay, lithocholylcholine inhibited acetylcholine-induced relaxation of rat aortic rings. These observations indicate that lithocholylcholine is a muscarinic receptor antagonist and provide further evidence that bile acids may have gastrointestinal signaling functions that extend beyond their effects on sterol metabolism, lipid absorption, and cholesterol elimination. Hybrid molecules created from bile acids and acetylcholine may be used to develop selective muscarinic receptor ligands.
AB - Previous work from our laboratory indicates that bile acids, specifically lithocholic acid conjugates, interact with muscarinic receptors on gastric chief cells. Structural similarities between acetylcholine and lithocholyltaurine suggest a potential molecular basis for their interaction with the same receptor. We synthesized a hybrid molecule consisting of the steroid nucleus of lithocholyltaurine and the choline moiety of acetylcholine. The new molecule, lithocholylcholine, is hydrolyzed by acetylcholinesterase. Lithocholylcholine inhibited binding of a cholinergic radioligand to Chinese hamster ovary cells expressing each of the five muscarinic receptor subtypes. The binding affinities (K1; micromolar) of lithocholylcholine for these receptors were: M3 (1.0) > M1 (2.7) > M2 (4.1) = M4 (4.9) > M5 (6.2). Lithocholylcholine inhibited intracellular signaling pathways mediated by interaction with M1, M2, and M3 muscarinic receptors. Regarding M3 receptors, lithocholylcholine was 10-fold more potent than lithocholyltaurine in terms of binding affinity and inhibition of acetylcholine-induced increases in inositol phosphate formation and mitogen-activated protein kinase phosphorylation. In a functional assay, lithocholylcholine inhibited acetylcholine-induced relaxation of rat aortic rings. These observations indicate that lithocholylcholine is a muscarinic receptor antagonist and provide further evidence that bile acids may have gastrointestinal signaling functions that extend beyond their effects on sterol metabolism, lipid absorption, and cholesterol elimination. Hybrid molecules created from bile acids and acetylcholine may be used to develop selective muscarinic receptor ligands.
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U2 - 10.1124/jpet.102.036376
DO - 10.1124/jpet.102.036376
M3 - Article
C2 - 12235229
AN - SCOPUS:0036784505
SN - 0022-3565
VL - 303
SP - 29
EP - 35
JO - Journal of Pharmacology and Experimental Therapeutics
JF - Journal of Pharmacology and Experimental Therapeutics
IS - 1
ER -