Clark M J, Emmerson P J, Mansour A, Akil H, Woods J H, Portoghese P S, Remmers A E, Medzihradsky F
Department of Pharmacology,University of Michigan, Ann Arbor, Michigan 48109-0632, USA.
J Pharmacol Exp Ther. 1997 Nov;283(2):501-10.
A C6 glioma cell line stably transfected with the rat delta opioid receptor (C6delta) was used to characterize receptor binding and G protein activation by both peptide and nonpeptide delta opioid ligands. The ligand binding affinities for [3H]naltrindole and [3H]pCl-[D-Pen2,D-Pen5]enkephalin (DPDPE) were similar to those observed in monkey brain membranes. The nonpeptide agonists, BW373U86 and SNC80, as well as peptide agonist [D-Ser2, L-Leu5]enkephalyl-Thr maximally stimulated [35S]GTPgammaS binding by 640, 654 and 576%, respectively, over basal. The peptide agonists, DPDPE and deltorphin II, both stimulated [35S]GTPgammaS binding by 375%. Etorphine, diprenorphine, oxymorphindole and 7-spiroindanyloxymorphone were also partial agonists in this assay, although they were less efficacious than deltorphin II. Stimulation of [35S]GTPgammaS binding by agonists was blocked completely by pertussis toxin pretreatment. Both delta-1 and delta-2 selective antagonists 7-benzylidenenaltrexone and a benzofuran analog of naltrindole displayed high affinity for the cloned receptor (0.04 and 0.08 nM) and antagonized the stimulation of [35S]GTPgammaS binding by BW373U86 and DPDPE with similar potencies. Other evidence suggesting the lack of receptor subtypes includes the finding that stimulation of [35S]GTPgammaS binding by receptor subtype selective ligands DPDPE and deltorphin II was not additive. BW373U86, SNC80 and DPDPE maximally inhibited forskolin-stimulated adenylyl cyclase. These cells highly express a homogeneous population of delta opioid receptor that couple to inhibitory Go/Gi proteins. Ligand affinity for the delta opioid receptor correlates with ligand EC50 values for stimulation of [35S]GTPgammaS binding.
用稳定转染大鼠δ阿片受体的C6胶质瘤细胞系（C6δ）来表征肽类和非肽类δ阿片配体的受体结合及G蛋白激活情况。[3H]纳曲吲哚和[3H]对氯苯甲酰-D-青霉胺2，D-青霉胺5-脑啡肽（DPDPE）的配体结合亲和力与在猴脑膜中观察到的相似。非肽类激动剂BW373U86和SNC80，以及肽类激动剂[D-丝氨酸2，L-亮氨酸5]脑啡肽-苏氨酸分别比基础水平最大程度地刺激[35S]GTPγS结合640%、654%和576%。肽类激动剂DPDPE和强啡肽II均刺激[35S]GTPγS结合375%。埃托啡、二丙诺啡、羟吗啡吲哚和7-螺茚满氧基吗啡在该试验中也是部分激动剂，尽管它们的效力低于强啡肽II。激动剂对[35S]GTPγS结合的刺激被百日咳毒素预处理完全阻断。δ-1和δ-2选择性拮抗剂7-亚苄基纳曲酮和纳曲吲哚的苯并呋喃类似物对克隆受体显示出高亲和力（分别为0.04和0.08 nM），并以相似的效力拮抗BW373U86和DPDPE对[35S]GTPγS结合的刺激。其他表明不存在受体亚型的证据包括以下发现：受体亚型选择性配体DPDPE和强啡肽II对[35S]GTPγS结合的刺激不是相加的。BW373U86、SNC80和DPDPE最大程度地抑制福斯高林刺激的腺苷酸环化酶。这些细胞高度表达与抑制性Go/Gi蛋白偶联的同质δ阿片受体群体。δ阿片受体的配体亲和力与刺激[35S]GTPγS结合的配体EC50值相关。
