Interaction of anandamide with the M1 and M4 muscarinic acetylcholine receptors
Interaction of anandamide with the M1 and M4 muscarinic acetylcholine receptors
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DOI：
10.1016/s0006-8993(01)02825-6
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发表时间：
2001-10-05
期刊：
影响因子：
2.9
通讯作者：
Wilson, K
中科院分区：
文献类型：
--
作者：
Christopoulos, A;Wilson, K
M-1和M-4毒蕈碱乙酰胆碱受体是大脑中最丰富的毒蕈碱受体亚型，参与学习和记忆。由于大麻素受体也在类似的大脑区域大量表达，并介导与乙酰胆碱相反的认知作用，本研究探讨了内源性大麻素激动剂anandamide及其代谢稳定的衍生物methanandamide，直接修饰CHO细胞膜中单独表达的人M-1和M-4受体的结合特性。实验使用拮抗剂[H-3] n -甲基东莨菪碱和[H-3]苯磺酸醌。当使用乙酰胆碱作为抑制配体时，在两个受体上观察到浅的双相等温线，其特征是每个受体的高亲和力和低亲和力结合的表观解离常数相似，但M-4的高亲和力位点比例（40-45%）大于M-1受体（17-20%）。相比之下，anandamide和methanandamide在较窄（低微摩尔）浓度范围内抑制两种放射性配体的结合。两个受体的单相等温线希尔系数显著大于1。这些影响不是由于所使用的车辆。进一步的饱和结合分析发现，anandamide能够显著降低[H-3]喹啉苄基苯甲酸酯标记的结合位点的表观亲和力和最大密度。有趣的是，合成大麻素激动剂对放射性配体结合没有明显的抑制作用。WIN55212-2，或大麻素CB1受体拮抗剂SR141716A。因此，这些数据为大麻酰胺通过与大麻素受体无关的非竞争机制调节毒蕈碱受体结合特性的直接作用提供了证据。(C) 2001年Elsevier Science by出版。
The M-1 and M-4 muscarinic acetylcholine receptors are the most abundant muscarinic receptor subtypes in the brain, and are involved in learning and memory, Because cannabinoid receptors are also abundantly expressed in similar brain regions and mediate opposite effects to acetylcholine on cognition, the present study investigated whether the endocannabinoid agonist, anandamide, and its metabolically stable derivative, methanandamide, directly modified the binding properties of the human M-1 and M-4 receptors individually expressed in CHO cell membranes. Experiments utilized the antagonists, [H-3]N-methylscopolamine and [H-3]quinuclidinyl benzilate. When acetylcholine was used as the inhibiting ligand, shallow, biphasic isotherms were observed at both receptors, characterised by similar apparent dissociation constants for high and low affinity binding at each receptor but with a greater proportion of high affinity sites at the M-4 (40-45%) than at the M-1 receptor (17-20%). In contrast, anandamide and methanandamide inhibited the binding of both radioligands over a narrow (low micromolar) concentration range. with monophasic isotherms characterized by Hill coefficients significantly greater than 1 at both receptors. These effects were not due to the vehicle used. Further saturation binding analyses found anandamide able to significantly reduce the apparent affinity and maximal density of binding sites labeled by [H-3]quinuclidinyl benzilate. Interestingly, no significant inhibition of radioligand binding was noted using the synthetic cannabinoid agonist. WIN55212-2, or the cannabinoid CB1 receptor antagonist, SR141716A. These data thus provide evidence for a direct role of anandamides in modulating muscarinic receptor binding properties through a non-competitive mechanism that is unrelated to their actions on cannabinoid receptors. (C) 2001 Published by Elsevier Science BY.