Molinari E J, Delbono O, Messi M L, Renganathan M, Arneric S P, Sullivan J P, Gopalakrishnan M
Neurological and Urological Diseases Research, Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, IL 60064-3500, USA.
Eur J Pharmacol. 1998 Apr 17;347(1):131-9. doi: 10.1016/s0014-2999(98)00084-3.
This study examined the binding and functional properties of human alpha7 neuronal nicotinic acetylcholine receptors stably expressed in human embryonic kidney (HEK) 293 cells following chronic treatment with nicotinic receptor ligands. Treatment of cells with (-)-nicotine (100 microM) for 120 h increased the Bmax values of [125I]alpha-bungarotoxin binding 2.5-fold over untreated cells. This effect was concentration-dependent (EC50) = 970 microM) and a 6-fold upregulation was observed with the maximal concentration of (-)-nicotine tested. Also, treatment of cells with ligands of varying intrinsic activities including (+/-)-epibatidine, (2,4)-dimethoxybenzylidene anabaseine (GTS-21) and 1,1-dimethyl-4-phenyl piperazinium iodide (DMPP) also upregulated [125I]alpha-bungarotoxin binding. A concentration-dependent upregulation of binding sites was also observed following treatment with the alpha7 nicotinic receptor antagonist, methyllycaconitine (EC50 = 92 microM) with a maximal upregulation of about 7-fold. Functionally, the peak amplitude of the whole-cell currents recorded by fast application of (-)-nicotine after chronic treatment of cells with concentrations of (-)-nicotine (1000 microM) or methyllycaconitine (10 microM) that elicited similar increases in binding levels (3.5-fold) resulted in increases of 2-fold (505 +/- 21 pA) and 6-fold (1820 +/- 137 pA) respectively in whole cell current amplitude compared to untreated cells (267 +/- 24 pA). These studies clearly demonstrate that long-term exposure to both activator and antagonist ligands can increase the density of alpha7 nicotinic receptors and can differentially enhance nicotinic receptor function.
本研究检测了在用烟碱型受体配体进行慢性处理后，稳定表达于人类胚胎肾（HEK）293细胞中的人类α7神经元烟碱型乙酰胆碱受体的结合特性和功能特性。用（-）-尼古丁（100微摩尔）处理细胞120小时后，[125I]α-银环蛇毒素结合的Bmax值比未处理细胞增加了2.5倍。这种效应具有浓度依赖性（EC50 = 970微摩尔），在测试的（-）-尼古丁最大浓度下观察到6倍的上调。此外，用具有不同内在活性的配体处理细胞，包括（±）-依匹哌啶、（2,4）-二甲氧基亚苄基假木贼碱（GTS-21）和1,1-二甲基-4-苯基哌嗪碘化物（DMPP），也上调了[125I]α-银环蛇毒素结合。在用α7烟碱型受体拮抗剂甲基lycaconitine处理后（EC50 = 92微摩尔），也观察到结合位点的浓度依赖性上调，最大上调约7倍。在功能上，在用浓度为（-）-尼古丁（1000微摩尔）或甲基lycaconitine（10微摩尔）慢性处理细胞后，快速施加（-）-尼古丁记录的全细胞电流峰值幅度在结合水平上引起了类似的增加（3.5倍），与未处理细胞（267±24皮安）相比，全细胞电流幅度分别增加了2倍（505±21皮安）和6倍（1820±137皮安）。这些研究清楚地表明，长期暴露于激活剂和拮抗剂配体均可增加α7烟碱型受体的密度，并可不同程度地增强烟碱型受体功能。
