用于脑毒蕈碱和烟碱胆碱能受体的亲和配体及相关试剂。

Affinity ligands and related agents for brain muscarinic and nicotinic cholinergic receptors.

作者信息

Abood L G, Saraswati M, Lerner-Marmarosh N, Hashmi M

机构信息

Department of Pharmacology, University of Rochester Medical Center, NY 14642.

出版信息

Biochem Pharmacol. 1993 May 25;45(10):2143-8. doi: 10.1016/0006-2952(93)90028-u.

DOI:10.1016/0006-2952(93)90028-u

PMID:8512596

Abstract

This study describes the chemical synthesis and receptor binding characteristics of various affinity ligands and related ligands for brain muscarinic and nicotinic cholinergic receptors, including the 4-bromoacetamidobenzoic acid esters of dimethylaminoethanol (DMBAB) and choline (BABC) and 4-iodoacetamidobenzoylcholine (IABC). The reversible binding of [3H]3-quinuclidinylbenzilate ([3H]QNB) to calf brain membranes was inhibited in a concentration-dependent and saturable manner by DMBAB, BABC, and IABC with Ki values of 8 x 10(-7), 3 x 10(-7) and 8 x 10(-7) M, respectively; the Ki values for inhibition of reversible binding of the nicotinic ligand, [3H]methylcarbamylcholine ([3H]-MCC), were 1 x 10(-6), 6 x 10(-8), and 1 x 10(-6) M, respectively. The Ki values for irreversible inhibition of [3H]QNB binding were 8 x 10(-7), 1 x 10(-7), and 2 x 10(-7) M for DMBAB, BABC, and IABC, respectively, and for [3H]MCC binding, 8 x 10(-5), 1 x 10(-5), and 2 x 10(-5) M, respectively. Although DMBAB was found to inhibit the QNB-induced hyperactivity in mice, it did not antagonize the toxic or other pharmacologic effects of oxotremorine. Structure-activity studies with various non-affinity analogues of the 4-aminobenzoate ester of dimethylaminoethanol and choline revealed that removal of the NH2 moiety from the phenyl group increased affinity for the muscarinic but not the nicotinic cholinergic site, and quaternization of the ester side chain greatly increased affinity for the muscarinic site. Dimethylation of NH2 in 4-aminobenzoylcholine decreased the affinity for both cholinergic sites. Replacement of NH2 by NO2 increased affinity for the muscarinic but not the nicotinic site, whereas quaternization of the 4-nitrobenzoyl ester markedly increased affinity for the nicotinic site while diminishing affinity for the muscarinic site. The findings indicate that DMBAB and its analogues are useful affinity ligands for examining the biochemical and functional characteristics of brain cholinergic receptors, particularly the muscarinic which has an affinity near the nanomolar concentration range.

摘要

本研究描述了各种用于脑毒蕈碱和烟碱胆碱能受体的亲和配体及相关配体的化学合成和受体结合特性，包括二甲基氨基乙醇（DMBAB）和胆碱（BABC）的4 - 溴乙酰氨基苯甲酸酯以及4 - 碘乙酰氨基苯甲酰胆碱（IABC）。DMBAB、BABC和IABC以浓度依赖性和饱和性方式抑制[³H]3 - 喹核醇基苯甲酸酯（[³H]QNB）与小牛脑膜的可逆结合，其Ki值分别为8×10⁻⁷、3×10⁻⁷和8×10⁻⁷ M；抑制烟碱配体[³H]甲基氨基甲酰胆碱（[³H]-MCC）可逆结合的Ki值分别为1×10⁻⁶、6×10⁻⁸和1×10⁻⁶ M。DMBAB、BABC和IABC对[³H]QNB结合的不可逆抑制的Ki值分别为8×10⁻⁷、1×10⁻⁷和2×10⁻⁷ M，对[³H]MCC结合的不可逆抑制的Ki值分别为8×10⁻⁵、1×10⁻⁵和2×10⁻⁵ M。尽管发现DMBAB可抑制小鼠中QNB诱导的活动亢进，但它并不拮抗氧震颤素的毒性或其他药理作用。对二甲基氨基乙醇和胆碱的4 - 氨基苯甲酸酯的各种非亲和类似物进行的构效关系研究表明，从苯基上去除NH₂部分会增加对毒蕈碱胆碱能位点而非烟碱胆碱能位点的亲和力，酯侧链的季铵化大大增加了对毒蕈碱位点的亲和力。4 - 氨基苯甲酰胆碱中NH₂的二甲基化降低了对两种胆碱能位点的亲和力。用NO₂取代NH₂增加了对毒蕈碱胆碱能位点而非烟碱胆碱能位点的亲和力，而4 - 硝基苯甲酸酯的季铵化显著增加了对烟碱胆碱能位点的亲和力，同时降低了对毒蕈碱胆碱能位点的亲和力。这些发现表明，DMBAB及其类似物是用于研究脑胆碱能受体生化和功能特性的有用亲和配体，特别是对毒蕈碱胆碱能受体，其亲和力接近纳摩尔浓度范围。