Research Center, Mochida Pharmaceutical Co., Ltd., 722 Uenohara, Jimba, Gotemba, 412-8524, Japan.
Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Dig Dis Sci. 2023 Feb;68(2):439-450. doi: 10.1007/s10620-022-07637-y. Epub 2022 Aug 10.
The specific role of the M muscarinic acetylcholine receptor in gastrointestinal motility under physiological conditions is unclear, due to a lack of subtype-selective compounds.
The objective of this study was to determine the region-specific role of the M receptor in gastrointestinal motility.
We developed a novel positive allosteric modulator (PAM) for the M receptor, PAM-369. The effects of PAM-369 on the carbachol-induced contractile response of porcine esophageal smooth muscle and mouse colonic smooth muscle (ex vivo) and on the transit in mouse small intestine and rat colon (in vivo) were examined.
PAM-369 selectively potentiated the M receptor under the stimulation of its orthosteric ligands without agonistic or antagonistic activity. Half-maximal effective concentrations of PAM activity for human, mouse, and rat M receptors were 0.253, 0.345, and 0.127 μM, respectively. PAM-369 enhanced carbachol-induced contraction in porcine esophageal smooth muscle and mouse colonic smooth muscle without causing any contractile responses by itself. The oral administration of 30 mg/kg PAM-369 increased the small intestinal transit in both normal motility and loperamide-induced intestinal dysmotility mice but had no effects on the colonic transit, although the M receptor mRNA expression is higher in the colon than in the small intestine.
This study provided the first direct evidence that the M receptor has different region-specific roles in the motility function between the small intestine and colon in physiological and pathophysiological contexts. Selective PAMs designed for targeted subtypes of muscarinic receptors are useful for elucidating the subtype-specific function.
由于缺乏亚型选择性化合物，M 毒蕈碱乙酰胆碱受体在生理条件下对胃肠道动力的确切作用仍不清楚。
本研究旨在确定 M 受体在胃肠道动力中的区域特异性作用。
我们开发了一种新型 M 受体的正变构调节剂（PAM），即 PAM-369。研究了 PAM-369 对猪食管平滑肌和小鼠结肠平滑肌（离体）中乙酰胆碱诱导的收缩反应以及对小鼠小肠和大鼠结肠（体内）转运的影响。
PAM-369 在其变构配体的刺激下选择性增强 M 受体，而无激动或拮抗活性。PAM 对人、鼠和大鼠 M 受体的半数有效浓度分别为 0.253、0.345 和 0.127μM。PAM-369 增强了猪食管平滑肌和小鼠结肠平滑肌中乙酰胆碱诱导的收缩反应，而自身不引起任何收缩反应。口服 30mg/kg PAM-369 增加了正常运动和洛哌丁胺诱导的肠道动力障碍小鼠的小肠转运，但对结肠转运没有影响，尽管 M 受体 mRNA 表达在结肠中高于小肠。
本研究首次提供了直接证据，表明 M 受体在生理和病理生理条件下对小肠和结肠的运动功能具有不同的区域特异性作用。针对毒蕈碱受体靶向亚型设计的选择性 PAMs 有助于阐明亚型特异性功能。
