Binding properties of C-truncated delta opioid receptors

目的：研究δ阿片受体Ｃ末端在受体结合配体的亲和力及选择性中的作用．方法：在中国苍鼠卵巢细胞（ＣＨＯ细胞）中分别稳定表达Ｃ末端截短３１个氨基酸残基及野生型δ阿片受体，用受体结合分析法研究表达产物与配体的结合特征．结果：表达得到典型突变受体克隆ＣＨＯＴ及野生型受体克隆ＣＨＯＷ．ＣＨＯＴ结合［３Ｈ］ｄｉｐｒｅｎｏｒｐｈｉｎｅ（Ｄｉｐ）及［３Ｈ］［ＤＡｌａ２，ＤＬｅｕ５］ｅｎｋｅｐｈａｌｉｎ（ＤＡＤＬＥ）的Ｋｄ值与ＣＨＯＷ一致，δ选择性激动剂对二者与［３Ｈ］Ｄｉｐ的结合均有很强的抑制作用，且Ｋｉ相似；而μ及κ选择性激动剂则对二者均无抑制作用．结论：δ阿片受体的Ｃ末端与受体结合配体的亲和力及选择性无关．     

亮氨酸—2—丙氨酸脑啡肽诱导在中国仓鼠卵巢细胞中稳定表达的？…

目的;在研究中国仓鼠卵巢细胞中稳定表达的δ阿片受体内吞现象及其Ｃ－末端在受体内吞中的作用。方法;用免疫荧光共聚焦显微镜显示受体的着膜;以耐酸性缓冲液洗涤法测定放射性配体－受体结合量确定受体内吞程度。结果：表达的野生和Ｃ－末端截知的ＤＯＲ都被正确转运到细胞膜上,激动剂「＾３Ｈ」亮氨酸－２－丙氨酸脑啡肽卵育诱导ＤＯＲ快速内吞,拮抗剂「＾３Ｈ」二丙诺啡则不能;     

（^3H）二氢埃托啡与大鼠脑膜阿片受体的结合

目的：观察二氢埃托啡（ＤＨＥ）与阿片受体的结合情况。方法：采用放射配体受体结合实验，观察了（＾３Ｈ）ＤＨＥ与大鼠脑膜阿片受体的结合，结果：饱和实验显示（＾３Ｈ）ＤＨＥ的结合呈高亲和力单一位点，Ｋｄ＝０．１９±０．０５ｎｍｏｌ．Ｌ＾－１，Ｂｍａｘ＝１１５±２１ｐｍｏｌ／ｇｐｒｏｔｅｉｎ，动力学实验表明（＾３Ｈ）ＤＨＥ与阿片受体结合极快，解离很慢，ＮａＣｌ１００ｍｍｏｌ．Ｌ＾－１＋鸟苷三磷酸（ＧＴＰ）     

［~3H］二氢埃托啡与大鼠脑膜阿片受体的结合

目的：观察二氢埃托啡（ＤＨＥ）与阿片受体的结合情况．方法：采用放射配体受体结合实验，观察了［３Ｈ］ＤＨＥ与大鼠脑膜阿片受体的结合．结果：饱和实验显示［３Ｈ］ＤＨＥ的结合呈高亲和力单一位点，Ｋｄ＝０１９±００５ｎｍｏｌ·Ｌ－１，Ｂｍａｘ＝１１５±２１ｐｍｏｌ／ｇｐｒｏｔｅｉｎ．动力学实验表明［３Ｈ］ＤＨＥ与阿片受体结合极快，解离很慢．ＮａＣｌ１００ｍｍｏｌ·Ｌ－１＋鸟苷三磷酸（ＧＴＰ）５０μｍｏｌ·Ｌ－１可使［３Ｈ］ＤＨＥ的Ｋｄ值提高为７８７ｎｍｏｌ·Ｌ－１，Ｂｍａｘ值不变．激动剂和拮抗剂的竞争抑制实验均表明［３Ｈ］ＤＨＥ与μ阿片受体的亲和力大于δ和κ受体．结论：ＤＨＥ对μ阿片受体具有一定选择性．     

Human μ-opioid receptor overexpressed in baculovirus system and its pharmacological characterizations

目的：高效表达具有类似哺乳动物特性的人μ阿片受体．方法：人μ阿片受体表达在重组杆状病毒感染的Ｓｆ９昆虫细胞中，用受体结合分析和ｃＡＭＰ分析研究表达产物的药理学特征．结果：［３Ｈ］二丙诺啡及［３Ｈ］羟甲芬太尼（Ｏｈｍ）的最大结合能力分别是９．１±０．７，６５２±０．２３ｎｍｏｌ／ｇ蛋白．μ选择性激动剂对［３Ｈ］二丙诺啡或［３Ｈ］Ｏｈｍ与表达受体的结合均有很强的抑制作用，而δ及κ激动剂则均无抑制作用．μ选择性激动剂有效抑制ｆｏｒｓｋｏｌｉｎ刺激的ｃＡＭＰ聚集，这种作用能被拮抗剂纳洛酮阻断．结论：在Ｓｆ９昆虫细胞中高效表达的人μ阿片受体保持着野生型人μ阿片受体的特征     

δ阿片受体研究新进展

目的综述δ阿片受体研究进展。方法应用功能表达、受体结合、基因定位突变、构建嵌合受体等方法。结果和结论克隆出δ阿片受体,为３７２个氨基酸,属Ｇ蛋白耦联受体,存在７次跨膜结构。δ阿片受体中的天门冬氨酸９５（Ａｓｐ９５）残基和Ａｓｐ１２８残基处于受体结合位点的关键区域。δ阿片受体中的赖氨酸（Ｌｙｓ１０８）残基阻止ＤＡＭＧＯ与δ受体的结合;δ阿片受体的第３个细胞外环决定了δ受体激动剂对δ受体的选择性。δ受体第４跨膜域中的丝氨酸（Ｓｅｒ１７７）被突变可使经典拮抗剂呈现激动剂的性质。     

三种阿片受体激动剂对突触传递的抑制作用

目的：比较不同浓度三种阿片受体激动剂对突触传递的抑制作用，方法：用细胞内记录和细胞外微电泳技术，于大鼠伏核脑片制备上记录神经元的兴奋性突触后电位和谷氨酸钠所致细胞膜去极化。结果：（Ｄ－Ａｌａ＾２，ＮＭｅ－Ｐｈｅ＾４，Ｇｌｙ－ｏｌ）－ｅｎｋｅｐｈａｌｉｎ（ＤＡＧＯ），（Ｄ－Ｐｅｎ＾２，５）－ｅｎｋｅｐｈａｌｉｎ（Ｄ－ＰＥＮ），ａｎｄｔｒａｎｓ（±）－３。４－ｄｉｃｈｌｏｒｏ－Ｎ－ｍｅｔｈｙｌ－Ｎ－（     

Antagonistic effect of orphanin FQ on opioid analgesia in rat

目的：研究孤啡肽（ＯＦＱ）对痛与阿片镇痛的影响．方法：脑室（ｉｃｖ）与鞘内（ｉｔｈ）给药，以大鼠甩尾模型测痛．结果：小剂量ＯＦＱ（０１μｇ）ｉｃｖ及ｉｔｈ给药对痛反应均无影响；较大剂量ＯＦＱ（０５－１０μｇ）可使痛反应增强．ＯＦＱ１－１０（ＯＦＱ的一个片段）ｉｃｖ对痛反应无影响．μ受体激动剂芬太尼（１μｇ）、δ激动剂ＤＳＬＥＴ（５μｇ）ｉｃｖ或ｉｔｈ给药，以及κ激动剂Ｕ５０４８８Ｈ（１μｇ）ｉｔｈ给药，可使痛阈明显增加．０１μｇ或１μｇＯＦＱ与上述药物合用后，痛阈增加明显减少（除鞘内与ＤＳＬＥＴ合用外）．结论：ＯＦＱ可增强大鼠的痛反应，在脑内对抗由μ和δ受体介导的阿片镇痛，在脊髓对抗由κ和μ但不是由δ受体介导的镇痛．     

β—胡萝卜素对^60Co—γ辐射诱发的大鼠T—淋巴细胞次黄嘌呤—鸟嘌呤…

目的：研究β－胡萝卜素（β－Ｃａｒ）对电离辐射诱导的突变的影响。方法：Ｔ－淋巴细胞克隆检测法测定大鼠Ｔ－淋巴细胞次黄嘌呤－鸟嘌呤磷酸核糖转移酶（ＨＧＰＲＴ）位点的突变率和硫代巴比妥酸（ＴＢＡ）法测定大鼠血丙二醛（ＭＤＡ），结果：＾６０Ｃｏγ３．７５Ｇｙ照射大鼠显著提高ＨＧＰＲ位点突变频率，ｉｇβ－Ｃａｒ１０和２０ｍｇ．ｋｇ＾－１突变频率明显降低（Ｐ〈０．０５），应用β－Ｃａｒ５ｍｇ．ｋｇ＾－１变化     

GM—CSF工程菌构建及鉴定

采用ＰＣＲ技术，从细胞中克隆粒细胞／巨噬细胞集落刺激因子（ＧＭ－ＣＳＦ）并在５′端设计上凝血酶切位点５个组氨酸密码子，起始密码子及ＥＣＯＲＩ酶切点位，在３′端设计上ＢａｍＨＩ酶切位点，将扩增产物酶切后克隆到ＰＢＶ２２０质粒的ＥＣＯＲＩ－ＨｉｎｄⅢ酶切位点，转化大肠杆菌ＤＨ５α筛选阳性重组子（Ｐ＾ＧＭ０９／ＤＨ５α）经细菌形态，菌落形态功生化鉴别均符合要求，在Ｅ．Ｃｏｌｉ中获得高效表达，表达量占体总     

Selectivity of ligand binding to opioid receptors in brain membranes from the rat, monkey and guinea pig

Conditions for the equilibrium binding to opioid receptor of [3H]sufentanil (mu selective), [3H][D-Pen2,D-Pen5]enkephalin (delta selective), and [3H]U69,593 (kappa selective) were established in membranes from rat brain cerebrum, monkey cortex, or guinea pig cerebellum. The selectivity index of various opioid alkaloids and peptides in binding to the mu, delta, or kappa opioid receptors was expressed as the ratio of their EC50 values in displacing two selective radiolabeled ligands: [3H]sufentanil/[3H](D-Pen2,D-Pen5)enkephalin (selectivity: mu/delta), [3H]sufentanil/[3H]U69,593 (selectivity: mu/kappa), or [3H][D-Pen2,D-Pen5]enkephalin/[3H]U69,593 (selectivity: delta/kappa). High resolution in binding selectivity was observed: in rat brain the mu/delta selectivity for Tyr-D-Ala-Gly-(Me)Phe-Gly-ol and sufentanil were 0.02 and 0.03, whereas for [D-Pen2,D-Pen5]enkephalin and ICI 174,864 they were 1,200 and 998. Compared to mu opiates, the specific binding of delta and kappa agonists was less sensitive to sodium. The results describe a routinely applicable methodological approach for the assessment of selective ligand binding to the mu, delta and kappa opioid receptors in rodent and monkey brain membranes.     

Ring substituted and other conformationally constrained tyrosine analogues of [D-Pen2,D-Pen5]enkephalin with delta opioid receptor selectivity.

The conformationally restricted, cyclic disulfide-containing delta opioid receptor selective enkephalin analogue [D-Pen2,D-Pen5] enkephalin (DPDPE) was modified by 2' (CH3) and 3' (I, OCH3, NO2, NH2) ring substitutions and by beta-methyl conformationally constrained beta-methyltyrosine derivatives in the 1 position. The potency and selectivity of these analogues were evaluated by bioassay in the mouse vas deference (MVD, delta receptor assay) and guinea pig ileum (GPI, mu receptor assay) assays and by radioreceptor binding assays in the rat brain using [3H]CTOP (mu ligand) and [3H][p-ClPhe4]DPDPE (delta ligand). The analogues showed highly variable potencies in the binding assays and in the bioassays. Aromatic ring substituents with positive Hammett constants had decreased potency, while substituents with negative Hammett constraints has increased potency for the opioid receptor. The most potent and most selective compound based on the binding was [2'-MeTyr1]DPDPE (IC50 = 0.89 nM and selectivity ratio 1310 in the binding assays). The 6-hydroxy-2-aminotetralin-2-carboxylic acid-containing analogue, [Hat1]DPDPE, also was highly potent and selective in both assays, demonstrating that significant modifications of tyrosine in enkephalins are possible with maintenance of high potency and delta opioid receptor selectivity. Of the beta-methyl-substituted Tyr1 analogues, [(2S,3R)-beta-MeTyr1]DPDPE was the most potent and the delta receptor selective. The results with substitution of beta-MeTyr or Hat instead of Tyr also demonstrate that topographical modification in a conformationally restricted ligand can significantly modulate both potency and receptor selectivity of peptide ligands that have multiple sites of biological activity.     

Synthesis of highly mu and delta opioid receptor selective peptides containing a photoaffinity group

A series of cyclic, conformationally constrained photolabile peptides related to the enkephalins and to somatostatin were designed and synthesized in an effort to develop highly selective and potent peptides for the delta and mu opioid receptors. The following new peptides were prepared and tested for their delta opioid receptor potency and selectivity in the guinea pig ileum assay, the mouse vas deferens assay, and the rat brain binding assay: H-Tyr-D-Pen-Gly-p-NH2Phe-D-Pen-OH (1, [p-NH2Phe4]DPDPE) and H-Tyr-D-Pen-Gly-p-N3Phe-D-Pen-OH (2, [p-N3Phe4]-DPDPE). The following new peptides were prepared and tested for their mu opioid receptor potency and selectivity in the same assays: H-D-Phe-Cys-p-NH2Phe-D-Trp-Lys-Thr-Pen-Thr-NH2 (3, [p-NH2Phe3]CTP) and D-Phe-Cys-p-N3Phe-D-Trp-Lys-Thr-Pen-Thr-NH2 (4, [p-N3Phe3]CTP). The delta selective photoaffinity peptide 2 displayed both high affinity (IC50 = 9.5 nM) and good selectivity (IC50 mu/IC50 delta = 1053) as an agonist at delta opioid receptors in bioassays, and 2 also displayed moderate affinity (33 nM) and excellent selectivity (IC50 mu/IC50 delta = 110) for rat brain delta opioid receptors. The mu selective photoaffinity peptide 4 displayed very weak affinity (8% contraction at 300 nM) at mu opioid receptors in bioassays, but good affinity (IC50 = 48.6 nM) and excellent selectivity (IC50 delta/IC50 mu = 412) for the rat brain mu opioid receptors. These conformationally constrained cyclic photoaffinity peptides may be useful tools to investigate the pharmacology of delta and mu opioid receptors.     

Absence of G-protein activation by mu-opioid receptor agonists in the spinal cord of mu-opioid receptor knockout mice

1. The ability of mu-opioid receptor agonists to activate G-proteins in the spinal cord of mu-opioid receptor knockout mice was examined by monitoring the binding to membranes of the non-hydrolyzable analogue of GTP, guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS). 2. In the receptor binding study, Scatchard analysis of [3H][D-Ala2,NHPhe4,Gly-ol]enkephalin ([3H]DAMGO; mu-opioid receptor ligand) binding revealed that the heterozygous mu-knockout mice displayed approximately 40% reduction in the number of mu-receptors as compared to the wild-type mice. The homozygous mu-knockout mice showed no detectable mu-binding sites. 3. The newly isolated mu-opioid peptides endomorphin-1 and -2, the synthetic selective mu-opioid receptor agonist DAMGO and the prototype of mu-opioid receptor agonist morphine each produced concentration-dependent increases in [35S]GTPgammaS binding in wild-type mice. This stimulation was reduced by 55-70% of the wild-type level in heterozygous, and virtually eliminated in homozygous knockout mice. 4. No differences in the [35S]GTPgammaS binding stimulated by specific delta1- ([D-Pen2,5]enkephalin), delta2-([D-Ala2]deltorphin II) or kappa1-(U50,488H) opioid receptor agonists were noted in mice of any of the three genotypes. 5. The data clearly indicate that mu-opioid receptor gene products play a key role in G-protein activation by endomorphins, DAMGO and morphine in the mouse spinal cord. They support the idea that mu-opioid receptor densities could be rate-limiting steps in the G-protein activation by mu-opioid receptor agonists in the spinal cord. These thus indicate a limited physiological mu-receptor reserve. Furthermore, little change in delta1-, delta2- or kappa1-opioid receptor-G-protein complex appears to accompany mu-opioid receptor gene deletions in this region.     

Characterization of high affinity opioid binding sites in rat periaqueductal gray P2 membrane

The periaqueductal gray (PAG) region of the midbrain has been implicated in both stimulation produced and opioid induced analgesia. In the present study the opioid binding characteristics of the PAG were examined with an in vitro radioligand binding technique. [3H]Ethylketocyclazocine (EKC), 2 nM, was used as a tracer ligand to nonselectively label mu, delta, and kappa binding sites in PAG enriched P2 membrane. The mu selective ligand [D-Ala2,N-methylPhe4,Glyol5]enkephalin (DAGO) competed with [3H]EKC for more than one population of binding sites with both high and low affinity. In contrast the delta selective ligand [D-Pen2,D-Pen5]enkephalin (DPDPE) and the kappa selective ligand trans-3,4-dichloro-N-methyl-N-[2-(1- pyrrolidinyl)cyclohexyl]benzeneacetamide, methane sulfonate, hydrate (U50,488H) each competed with [3H]EKC for a single population of binding sites with low affinity. DPDPE and U50,488H also competed with 2 nM [3H]DAGO for a single population of binding sites with similar low affinity. DAGO and not DPDPE competed with 2 nM [3H][D-Ala2,D-Leu5]enkephalin (DADLE) with high affinity. 2 nM [3H]DPDPE did not substantially label PAG enriched P2 membrane, and 1 nM DAGO competed with all specific [3H]DPDPE binding which was observed. These binding data are consistent with the presence of a single population of mu selective high affinity binding sites in PAG enriched P2 membrane to which delta ligands and kappa ligands have low affinity.     

Modulation of mu, delta and kappa opioid receptors in rat brain by metal ions and histidine

The effect of zinc (Zn2+) and several other trace elements was studied on the binding of the opioid receptor agonists [3H] DAGO [( ([Tyr-D-Ala-Gly-Methyl-Phe-Glyol]-enkephalin)a, [3H] DSTLE ([Tyr-D-Ser-Gly-Phe-Leu-Thr]-enkephalin) and [3H] EKC (ethylketocyclazocine), which are specific for the mu, delta and kappa opioid receptors, respectively, in the cerebral cortex of the rat. Physiological concentrations of zinc were inhibitory to mu receptor binding, whereas the delta and kappa receptors were relatively insensitive to this inhibition. Scatchard analysis, using these opioid agonists, revealed curvilinear plots; concentrations of zinc equal to or less than the IC50 (the concentration of cation which caused 50% inhibition of the binding of opioid ligand to its receptor), increased the KD (the dissociation constant) of all three subtypes of receptor, with no effect on the Bmax (the maximum number of binding sites) and abolished the high affinity sites of the delta and kappa receptors. Copper, cadmium and mercury also inhibited the binding of these ligands to their receptors. Histidine was most effective in preventing the inhibitory effects of zinc and copper, whereas it was less effective on cadmium and without any effect on the inhibition caused by mercury. Magnesium and manganese were stimulatory to opioid receptor binding, whereas cobalt and nickel had dual (stimulatory and inhibitory) effects. Non-inhibitory concentrations of zinc significantly decreased the stimulatory effects of magnesium and manganese on the mu and delta receptors, suggesting that part of the effect of zinc was through prevention of the actions of stimulatory cations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative pharmacological properties and functional coupling of mu and delta opioid receptor sites in human neuroblastoma SH-SY5Y cells

The characteristics of mu and delta opioid receptor sites present in human neuroblastoma SH-SY5Y cells were investigated using [D-Ala2-N-methyl-Phe4-Gly-(01)5]enkephalin (DAGO) and [2-D-penicillamine, 5-D-penicillamine]enkephalin (DPDPE), which are the most selective radioligands available for mu and delta sites, respectively. Scatchard analysis of the saturation isotherms revealed high affinity binding to a single class of sites for both [3H]DAGO (mu) and [3H]DPDPE (delta). [3H]DAGO labeled twice the number of sites compared to the binding capacity of [3H]DPDPE, yielding a mu/delta ratio of 2:1. Selective suppression of [3H]diprenorphine binding by specific opioid "blocking" ligands also showed a predominance of mu receptors, representing 65-70% of the total opioid sites. Competition binding studies carried out with a series of opiates and opioid peptides displayed higher potencies of mu- and delta-selective ligands in displacing the specific binding of [3H]DAGO and [3H]DPDPE, respectively. The [3H]diprenorphine/agonist competition curves were biphasic, indicating the high and low affinity states of mu and delta receptor sites in SH-SY5Y cells. Guanine nucleotide and sodium had differential effects on the agonist affinity and the proportion of high affinity states of mu and delta receptors. The mu and delta receptor sites were shown to be functionally coupled to adenylate cyclase. All of these data support the independent existence of mu and delta receptor types in human neuroblastoma cells. SH-SY5Y cells, therefore, represent a suitable model for investigating opioid-mediated responses in nerve cell populations.     

Comparative binding of mu and delta selective ligands in whole brain and pons/medulla homogenates from rat: affinity profiles of fentanyl derivatives

The comparative binding characteristics of the mu opioid receptor selective ligand [3H]-[D-Ala2-MePhe4-glyol5]enkephalin [( 3H]-DAGO) and of the delta receptor ligand [3H]-[D-Pen2, D-Pen5]enkephalin[( 3H]-DPDPE) have been studied in homogenates of both whole brain and of pons/medulla regions from the rat. The receptor affinities of five 4-anilinopiperidine drugs (fentanyl derivatives) and of morphine have been determined by inhibition studies, using [3H]-DAGO and [3H]-DPDPE as markers of the mu and delta opioid binding sites, respectively. The concentration of delta opioid sites in pons/medulla was found to be approximately one third that of mu sites. The concentrations of both mu and delta sites in whole brain were similar to that of mu sites in pons/medulla. The rank order of affinities of the unlabelled drugs was dissimilar at the mu and delta sites. The most potent fentanyl derivatives exhibited negligible preference for the mu or delta sites, in contrast to the least potent compound, alfentanil which showed an extremely high mu-site selectivity.