Mechanism-based approach to the successful prevention of cocaine inhibition of the neuronal (alpha 3 beta 4) nicotinic acetylcholine receptor.
Mechanism-based approach to the successful prevention of cocaine inhibition of the neuronal (alpha 3 beta 4) nicotinic acetylcholine receptor.
复制标题
基于机制的方法成功预防可卡因对神经元（α3β4）烟碱乙酰胆碱受体的抑制。
DOI：
10.1021/bi034838l
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Hess,GeorgeP
中科院分区：
文献类型：
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作者：
Krivoshein,ArcadiusV;Hess,GeorgeP
烟碱型乙酰胆碱受体（nAChR）属于五种通道形成蛋白的家族，其调节神经系统的大约1012个细胞之间的通信。非竞争性抑制剂可卡因和MK-801 [（+）-地佐环平，一种抗惊厥药]抑制肌肉型nAChR（）的最低机制表明，它们与一个调节位点结合，对闭合通道形式的亲和力高于开放通道形式，从而使平衡向闭合通道形式转移并抑制受体功能。该机制预测，与该调节位点结合的化合物对开放通道构象的亲和力等于或高于对闭合通道构象的亲和力，将阻止受体抑制（）。神经元形式的受体是否也有类似的行为？用快速化学动力学方法研究了可卡因和MK-801抑制神经元nAChR的机制。在这些研究中使用在HEK 293细胞中稳定表达的α3β4 nAChR。全细胞电流起源于一个主要和次要的nAChR亚型。仅对主要亚型进行了表征。对于显性的快速脱敏亚型，控制受体激活位点的氨甲酰胆碱解离常数Kd为2 mM;通道开放平衡常数Φ-1为4;显性脱敏速率常数k34为20 s-1。在高浓度和低浓度的氨甲酰胆碱下，辅酶A非竞争性抑制受体，表观KI分别为84和26 μM，在该浓度下受体主要以开放或闭合通道形式存在。MK-801也获得了类似的结果。一个组合合成的RNA配体和可卡因类似物减轻可卡因抑制这种神经元受体。
The nicotinic acetylcholine receptor (nAChR) belongs to a family of five channel-forming proteins that regulate communication between the approximately 1012cells of the nervous system. A minimum mechanism of inhibition of the muscle-type nAChR () by the noncompetitive inhibitors cocaine and MK-801 [(+)-dizocilpine, an anticonvulsant] indicated they bind to a regulatory site, with higher affinity for the closed-channel form than for the open-channel form, thus shifting the equilibrium toward the closed-channel form and inhibiting receptor function. The mechanism predicts that compounds that bind to this regulatory site with equal or higher affinity for the open-channel conformation than for the closed-channel conformation will prevent receptor inhibition (). Does a neuronal form of the receptor behave similarly? The mechanism of inhibition of the neuronal nAChR by cocaine and MK-801 using rapid chemical kinetic techniques was investigated. The α3β4 nAChR stably expressed in HEK 293 cells was used in these investigations. Whole-cell currents originated from a major and minor nAChR isoform. Only the major isoform has been characterized. For the dominant, rapidly desensitizing isoform, the carbamoylcholine dissociation constant for the site controlling receptor activation,Kd, is 2 mM; the channel-opening equilibrium constant, Φ-1, is 4; and the dominant desensitization rate constant,k34, is 20 s-1. Cocaine inhibits the receptor noncompetitively, with an apparentKIof 84 and 26 μM at high and low carbamoylcholine concentrations, at which concentrations the receptor is mainly in the open- or closed-channel form, respectively. Similar results were obtained with MK-801. A combinatorially synthesized RNA ligand and a cocaine analogue alleviated cocaine inhibition of this neuronal receptor.