Tang T, Kiang J G, Cox B M
Department of Pharmacology, Uniformed Services University of Health Sciences, Bethesda, Maryland.
J Pharmacol Exp Ther. 1994 Jul;270(1):40-6.
The neuronal cell line ND8-47 (neuroblastoma x dorsal root ganglion neuron hybrid) expressed opioid delta-type receptors. We report opioid-induced changes in cytosolic intracellular free calcium ([Ca++]i) in differentiated ND8-47 cells. Delta-opioid receptor agonists induced a transient (< 2 min) increase in [Ca++]i in a concentration-dependent fashion with the potency order: [D-Ser2,Leu5]enkephalin-Thr (DSLET) > or = deltorphin II > [D-Pen2,5] enkephalin. Their effects were blocked by naloxone (IC50 = 20 nM) and naltrindole (IC50 = 2.5 nM). Selective mu and kappa receptor agonists had no effect on [Ca++]i. The subtype specific delta receptor antagonists, 7-benzylidene naltrexone (delta-1) and naltriben (delta-2), were used to characterize further the subtype of delta receptors mediated by this response. Naltriben was more potent than 7-benzylidene naltrexone in antagonizing the DSLET-induced increase in [Ca++]i. The increase in [Ca++]i induced by DSLET was blocked by nifedipine (1 microM) or verapamil (1 microM), and was not observed in the absence of external calcium. Changes in [Ca++]i also were measured in single ND8-47 cells. The percentage of cells responding to DSLET (1 microM), deltorphin-II (1 microM) and [D-Pen2,5]enkephalin (1 microM) were 86, 84 and 37%, respectively. The results suggest that an increase in [Ca++]i induced by opioids is mediated through opioid delta receptors which can activate dihydropyridine-sensitive Ca++ channels.
神经元细胞系ND8 - 47（神经母细胞瘤x背根神经节神经元杂交细胞系）表达阿片δ型受体。我们报道了阿片类物质诱导的分化型ND8 - 47细胞胞质内游离钙（[Ca++]i）的变化。δ - 阿片受体激动剂以浓度依赖方式诱导[Ca++]i短暂（<2分钟）升高，效力顺序为：[D - Ser2，Leu5]脑啡肽 - Thr（DSLET）≥强啡肽II>[D - Pen2，5]脑啡肽。它们的作用被纳洛酮（IC50 = 20 nM）和纳曲吲哚（IC50 = 2.5 nM）阻断。选择性μ和κ受体激动剂对[Ca++]i无影响。亚型特异性δ受体拮抗剂，7 - 亚苄基纳曲酮（δ - 1）和纳曲苄（δ - 2），被用于进一步表征介导此反应的δ受体亚型。在拮抗DSLET诱导的[Ca++]i升高方面，纳曲苄比7 - 亚苄基纳曲酮更有效。DSLET诱导的[Ca++]i升高被硝苯地平（1μM）或维拉帕米（1μM）阻断，且在无细胞外钙时未观察到这种升高。还在单个ND8 - 47细胞中测量了[Ca++]i的变化。对DSLET（1μM）、强啡肽 - II（1μM）和[D - Pen2，5]脑啡肽（1μM）有反应的细胞百分比分别为86%、84%和37%。结果表明，阿片类物质诱导的[Ca++]i升高是通过阿片δ受体介导的，该受体可激活对二氢吡啶敏感的Ca++通道。
