μ阿片受体功能调节

μ阿片受体识别选择性配基的区域还有争论 ,受体的TM内氨基酸的空间取向影响选择性配基的亲和性。阿片受体活性的调节可能并没有涉及到它们将GTP和G蛋白相联系的能力 ,以及相继的异源三聚体的解离能力。激动剂诱导的 μ受体的磷酸化与受体的脱敏是否相关尚无定论。μ受体细胞内过程需要形成多蛋白复合物 ,形成受体信号复合物的细胞蛋白募集很重要。通用转录因子之间的相互作用决定受体基因的转录是很明确的。     

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。     

Modifications of the cyclic mu receptor selective tetrapeptide Tyr‐c[d‐Cys‐Phe‐d‐Pen]NH2 (Et): effects on opioid receptor binding and activation

Abstract: The previously described cyclic mu opioid receptor‐selective tetrapeptide Tyr‐c[d ‐Cys‐Phe‐d ‐Pen]NH₂ (Et) (JOM‐6) was modified at residues 1 and 3 by substitution with various natural and synthetic amino acids, and/or by alteration of the cyclic system. Effects on mu and delta opioid receptor binding affinities, and on potencies and efficacies as measured by the [³⁵S]‐GTPγS assay, were evaluated. Affinities at mu and delta receptors were not influenced dramatically by substitution of Tyr¹ with conformationally restricted phenolic amino acids. In the [³⁵S]‐GTPγS assay, all of the peptides tested exhibited a maximal response comparable with that of fentanyl at the mu opioid receptor, and all showed high potency, in the range0.4–9 nm . However, potency changes did not always correlate with affinity, suggesting that the conformation required for binding and the conformation required for activation of the opioid receptors are different. At the delta opioid receptor, none of the peptides were able to produce a response equivalent to that of the full delta agonist BW 373,U86 and only one had an EC₅₀ value of less than 100 nm . Lastly, we have identified a peptide, d ‐Hat‐c[d ‐Cys‐Phe‐d ‐Pen]NH₂ (Et), with high potency and > 1000‐fold functional selectivity for the mu over delta opioid receptor as measured by the [³⁵S]‐GTPγS assay.     

Development and validation of opioid ligand–receptor interaction models: The structural basis of mu vs. delta selectivity

Abstract: Opioid receptor binding conformations for two structurally related, conformationally constrained tetrapeptides, JOM‐6 (µ receptor selective) and JOM‐13 (δ receptor selective), were deduced using conformational analysis of these ligands and analogs with additional conformational restrictions. Docking of these ligands in their binding conformations to opioid receptor structural models, based upon the published rhodopsin X‐ray structure, implicates specific structural features of the µ and δ receptor ligand binding sites as forming the basis for the µ selectivity of JOM‐6 and the δ selectivity of JOM‐13. In particular, the presence of E229 in the µ receptor (in place of the corresponding D210 of the δ receptor) causes an adverse electrostatic interaction with C‐terminal carboxylate‐containing ligands, resulting in the observed preference of ligands with an uncharged C‐terminus for the µ receptor. In addition, the requirement that the Phe³ side chain of JOM‐13 assume a gauche orientation for optimal δ binding, whereas the Phe³ side chain of JOM‐6 must be in a trans orientation for high‐affinity µ binding can be largely attributed to the steric effect of replacement of L300 of the δ receptor by W318 of the µ receptor. Testing this hypothesis by examining the binding of JOM‐6 and several of its key analogs with specific µ receptor mutants is described. Our initial results are consistent with the proposed ligand–receptor interaction models.     

阿片依赖病理过程中NMDA受体与阿片受体的相互作用及分子机制

阿片依赖的病理生理学基础与机体长期接触阿片类物质后产生的代偿性适应相关。近年来研究发现 ,NMDA受体拮抗剂、抗体和反义核酸能抑制阿片躯体和精神依赖。该文从神经生化和分子生物学角度 ,综述了NMDA受体作用系统与阿片受体作用系统的相互作用以及NMDA受体参与阿片依赖的分子机制 ,并评价了NMDA受体拮抗剂及其他相关物质治疗阿片依赖的应用前景     

Selective enhancement of fentanyl-induced antinociception by the delta agonist SNC162 but not by ketamine in rhesus monkeys: Further evidence supportive of delta agonists as candidate adjuncts to mu opioid analgesics

Mu-opioid receptor agonists such as fentanyl are effective analgesics, but their clinical use is limited by untoward effects. Adjunct medications may improve the effectiveness and/or safety of opioid analgesics. This study compared interactions between fentanyl and either the noncompetitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist ketamine or the delta-opioid receptor agonist SNC162 [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-phenyl)methyl]-N,N-diethylbenzamide] in two behavioral assays in rhesus monkeys. An assay of thermal nociception evaluated tail-withdrawal latencies from water heated to 50 and 54 °C. An assay of schedule-controlled responding evaluated response rates maintained under a fixed-ratio 30 schedule of food presentation. Effects of each drug alone and of three mixtures of ketamine + fentanyl (22:1, 65:1, 195:1 ketamine/fentanyl) or SNC162 + fentanyl (59:1, 176:1, 528:1 SNC162/fentanyl) were evaluated in each assay. All drugs and mixtures dose-dependently decreased rates of food-maintained responding, and drug proportions in the mixtures were based on relative potencies in this assay. Ketamine and SNC162 were inactive in the assay of thermal antinociception, but fentanyl and all mixtures produced dose-dependent antinociception. Drug interactions were evaluated using dose-addition and dose-ratio analysis. Dose-addition analysis revealed that interactions for all ketamine/fentanyl mixtures were additive in both assays. SNC162/fentanyl interactions were usually additive, but one mixture (176:1) produced synergistic antinociception at 50 °C. Dose-ratio analysis indicated that ketamine failed to improve the relative potency of fentanyl to produce antinociception vs. rate suppression, whereas two SNC162/fentanyl mixtures (59:1 and 176:1) increased the relative potency of fentanyl to produce antinociception. These results suggest that delta agonists may produce more selective enhancement than ketamine of mu agonist-induced antinociception.     

近年来戒毒药物的研究进展

目的对近年来戒毒药物的研究进展作一综述。方法查阅近年来国内外公开发表的有关研究论文 ,按戒毒药物的作用靶点分类汇总。结果与结论目前戒毒药物的作用靶点主要包括阿片受体、α2 受体、DA2 受体、M受体、NMDA受体以及钙离子通道等 ,与此相对应的戒毒药物均具有较好的疗效。寻找有效的成瘾药物治疗的作用靶点以及在分子水平上研制新的戒毒药物是目前此类工作的研究方向     

吗啡镇痛耐受大鼠中脑导水管周围灰质μ受体和δ受体协同表达下调

目的:测定吗啡镇痛耐受大鼠中脑导水管周围灰质(PAG)中μ受体和δ受体mRNA和蛋白表达的变化,以进一步探索吗啡耐受的发生机制。方法:健康成年♂Wistar大鼠32只,随机平均分为生理盐水对照组(NS组,n=16)和吗啡组(MS组,n=16)。采用盲法进行给药和疼痛行为测定。每天早、晚两次皮下注射(sc)药物并于上午注射前、后30 min测定大鼠的热甩尾潜伏期(TFL)作为痛阈指标。NS组和MS组分别sc生理盐水1 ml·kg-1和吗啡10 mg·kg-1,连续注射7 d,d8早晨各组分别取8只处死,剩余大鼠(分别记为NSN组和MSN组)d8早、晚两次sc纳洛酮0.4 mg·kg-1,并在d9处死。以TFL恢复至基础水平作为出现吗啡耐受的标准。采用免疫组织化学染色方法和实时定量PCR法分别检测PAG中μ和δ受体的蛋白表达和mRNA表达。结果:观察期两组大鼠的体重增加量在组间差异无显著性。两组大鼠每天注射前测定的TFL差异无显著性。MS组在d1 sc吗啡后TFL明显升高(P<0.05);在d2应用吗啡后,TFL升高达到最高值,且明显高于d1用药后水平(P<0.05),随后该组应用吗啡后的TFL逐渐降低,直至d7用药后TFL降至基础水平(P>0.05)。应用纳洛酮后,MSN亚组的TFL与NS组、NSN亚组以及基础值相比差异无显著性。连续应用吗啡7 d后,MS组PAG中μ和δ受体的蛋白表达和mRNA表达均较NS组显著降低(P<0.05)。结论:PAG中μ受体和δ受体共同参与了吗啡耐受机制,而且吗啡耐受大鼠PAG中μ受体和δ受体发生了协同表达下调。     

Efficacy and safety of dual opioid therapy

There is some evidence for a partial opioid switching or an ‘add on’ approach to opioid dosing strategies. Preclinical and clinical findings suggest different activation profiles for the stimulation of the mu subtypes, raising the questions about what might occur with combinations of these substances. In the postoperative setting, it seems that the analgesic effect of the combination at equivalent doses is similar to that produced by the individual components, not adding particular advantages. However, adverse effects seem to be reduced with the combination of morphine/oxycodone, when given in doses equianalgesic to individual opioids. The reduction of opioid-induced postoperative adverse effects may have important clinical implications, given that adverse effects may prolong length of stay and hospitalization costs. Thus, in the acute postoperative setting, a reduction of adverse effects may be expected. In chronic pain, information is still in the infancy, but opioid combination therapy may have greater advantages in improving the opioid response. The possibility to clinically translate opioid combinations into practice, as demonstrated in some animal models, depends on a broad number of factors implicated in the pain process. More research is needed to better elucidate these issues in the near future.     

Role of delta opioid efficacy as a determinant of mu/delta opioid interactions in rhesus monkeys

Delta opioid agonists can selectively enhance the antinociceptive effects of mu opioid agonists without enhancing some other, potentially undesirable mu agonist effects. However, the degree of delta receptor efficacy required to produce this profile of interactions is unknown. To address this issue, the present study examined interactions produced by the mu agonist fentanyl and the intermediate-efficacy delta opioid MSF61 in rhesus monkeys. For comparison, interactions were also examined between fentanyl and the relatively high-efficacy delta agonist SNC243A and the delta antagonist naltrindole, which has negligible efficacy at delta receptors. Two different behavioral procedures were used: (a) a warm-water tail-withdrawal assay of thermal nociception, and (b) an assay of schedule-controlled responding for food reinforcement. Drug interactions within each procedure were evaluated using dose-addition analysis to compare experimental results with expected additivity. Drug interactions across procedures were evaluated using dose-ratio analysis to assess relative potencies to produce antinociception vs. response-rate suppression. As expected, dose-addition analysis found that fentanyl/SNC243A interactions were superadditive in the assay of antinociception but additive in the assay of schedule-controlled responding. Conversely, fentanyl/MSF61 interactions were generally additive in both procedures, and fentanyl/naltrindole interactions were additive or subadditive in both procedures. Dose-ratio analysis found that fentanyl alone produced antinociception and rate suppression with similar potencies. Some fentanyl/SNC243A mixtures produced antinociception with up to 4-fold greater potency than rate-suppression. However, fentanyl/MSF61 and fentanyl/naltrindole mixtures produced antinociception with lower potency than rate suppression. These results suggest that relatively high delta receptor efficacy is required for mu/delta antinociceptive synergy.     

Does electroconvulsive shock therapy work through opioid mechanisms?

It is now well-established that electroconvulsive shock (ECS) is the most effective treatment for severe depression. Over the past two decades a great deal of new information has been obtained regarding its neuropharmacological basis. The present review examines evidence that the behavioural and mood-elevating actions of ECS are mediated through changes in the function of opioid receptors or their endogenous transmitters. The recent discovery of stable, non-peptide ligands for the δK - and δ-receptor subtypes are detailed, and the prospects for a new phase of research in this area are expounded.     

μ阿片受体基因内含子2多态性与美沙酮维持治疗剂量的关联分析

目的：探讨M阿片受体基因内含子2的两个单核苷酸多态性位点（Singlenucleotidepoly—morphism,SNP）rs9479757和rs2075572与海洛因成瘾者关沙酮维持治疗剂量的相关性。方法：应用TaqMan荧光技术检测68例美沙酮维持治疗病例的rs9479757和rs2075572的基因型并进行与美沙酮维持剂量高低的关联分析。结果：rs9479757和rs2075572在美沙酮维持治疗高、低剂量组间的分布差异无统计学意义;rs9479757和rs2075572各基因型与美沙酮维持治疗剂量差异无统计学意义。结论：肚阿片受体基因内含子2的两个SNP（rs9479757和rs2075572）多态性与海洛因成瘾者美沙酮维持剂量的高低无明显相关性。     

Sex differences in the potency of κ opioids and mixed-action opioids administered systemically and at the site of inflammation against capsaicin-induced hyperalgesia in rats

Rationale Sex differences in the potency of the antinociceptive effects of κ opioids have been reported in various acute pain models with evidence suggesting that these sex differences are mediated by activity in the N-methyl-d-aspartate (NMDA) system. Objectives The purpose of the present study was to evaluate sex differences in the antihyperalgesic actions of selected κ and mixed-action opioids in a persistent pain model and determine if the NMDA system modulates these effects in a sexually dimorphic manner. Methods Using gonadally intact male and female F344 rats, hyperalgesia was induced by local administration of capsaicin in the tail, after which the tail was immersed in a mildly noxious thermal stimulus (45°C water), and tail-withdrawal latency measured. Opioids were then administered systemically (s.c.) and locally (in the tail) alone, and in selected combinations with the noncompetitive NMDA antagonist dextromethorphan. Results When administered systemically and locally, the κ opioids spiradoline, U69,593 and U50,488, and the mixed-action opioids butorphanol and nalbuphine, produced dose-dependent antihyperalgesic effects. Whereas the κ opioids were generally more potent in males, sex differences were not observed with the mixed-action opioids. Peripheral receptor activity was confirmed for local administration of κ opioids by the antagonism observed after local, but not intracerebroventricular (i.c.v.), administration of the κ antagonist nor-binaltorphamine (nor-BNI). Dextromethorphan was equally potent in attenuating the antihyperalgesia induced by κ opioids in both males and females. Conclusions These findings demonstrate sex differences in κ opioid activity in a persistent pain model. Although an NMDA antagonist blocked the effects of κ opioids in this model, these effects were not sexually dimorphic as reported in most acute pain models.     

曲马朵急性戒断反应诱导小鼠大脑皮层μ受体mRNA表达增加

目的 :从分子水平探讨曲马朵急性戒断机理及 5 -羟色胺酸、育亨宾对曲马朵急性戒断反应的影响。方法 :利用RT -PCR技术研究小鼠大脑皮层 μ受体mRNA表达的变化。 结果 :曲马朵急性戒断小鼠 μ受体mRNA的表达明显升高 ,增加了 15 3.3% ,而育亨宾和 5 -HTP可抑制曲马朵急性戒断诱导的 μ受体mRNA改变。 结论 :中枢 5 -羟色胺系统和去甲肾上腺素系统对曲马朵急性戒断诱导的小鼠大脑皮层 μ受体mRNA高表达具有调节作用     

Opioid receptor affinity and selectivity effects of second residue and carboxy terminal residue variation in a cyclic disulfide-containing opioid tetrapeptide

The previously described cyclic, delta opioid receptor-selective tetrapeptide H-Tyr-d -Cys-Phe-d -Pen-OH, where Pen, penicillamine, is β,β-dimethylcysteine, was modified at residues 2 and 4 by varying combinations of d - and l -Cys and d - and l -Pen, and effects on mu and delta opioid receptor binding affinities and on potency in the mouse vas deferens (MVD) smooth muscle assay were evaluated. A comparison was drawn between consequences of alterations in this series of analogs and those of analogous modifications in the related cyclic pentapeptide series which includes the highly delta receptor-selective [d -Pen²,d -Pen⁵]enke-phalin, DPDPE. Unlike effects observed in the cyclic pentapeptide series, the mu receptor binding affinities of the cyclic tetrapeptides are not dramatically influenced by substitution of Pen for Cys at residue 2. Conversely, while binding of the pentapeptides is only slightly affected by alteration of the chirality of the carboxy-terminal residue, modification of stereochemistry at the carboxy terminus in the tetrapeptides critically alters binding behavior at both mu and delta sites. In contrast with the pentapeptide series, the tetrapeptides appear to be highly dependent upon primary sequence for binding and activity, as only the lead compound binds with high affinity to the delta site. Results suggest that the less flexible cyclic tetrapeptides, lacking the Gly³ residue, display more stringent structural requirements for binding and activity than do the corresponding cyclic pentapeptides.     

Functional interactions between μ opioid and I1-imidazoline receptors

OBJECTIVE To study the role of I1-Imidazoline receptor(I1R) in opioid dependence.METHODS Subcellular location of μ opioid receptor(MOR) and IRAS was investigated by immunocytochemistry.The interaction between MOR and IRAS was studied by co-immunoprecipitation and fluorescence resonance energy transfer(FRET).Further more,whether the interactions between IRAS and MOR would affect the signaling and the adaptation of MOR was studied in the cells expressing MOR and IRAS.RESULTS We found that MOR and IRAS colocalized in the HEK293 cells transfected MOR and IRAS and in the neurons of the cerebral cortex and hippocampus.Coimmunoprecipitation and FRET assays showed that there were interactions between the IRAS and MOR.High concentration reductant DTT did not interrupt the interactions,suggesting that the interactions were not mediated by disulfide bond.Further more,we found that the interactions did not influence the expression and affinity of MOR,as well as the activation of G proteins,adenylate cyclase and extracellular signal-regulated kinase(ERK) phosphorylation coupled to MOR after stimulated by DAMGO.However,over-expression of IRAS could attenuate DAMGO-induced MOR desensitization and internalization,accelerate MOR resensitization in the cells co-expressing IRAS and MOR,which probably by increasing the rate of dephosphorylation and recycling of MOR.The molecular mechanisms for that were on studying.CONCLUSIONThese findings indicate I1R is an important molecular to modulate opioid functions,and provide the further evidence to support I1R as a new target for treating opioid addiction.     

Shadows across μ-Star? Constitutively active μ-opioid receptors revisited

Constitutively active μ-opioid receptors (μ* receptors) are reported to be formed following prolonged agonist treatment of cells or whole animals. μ* receptors signal in the absence of activating ligand and a blockade of μ* activation of G-proteins by naloxone and naltrexone has been suggested to underlie the profound withdrawal syndrome precipitated by these antagonists in vivo. In this issue of the Journal, Divin et al. examined whether treatment of C6 glioma cells with μ-opioid receptor agonists produced constitutively active μ-opioid receptors or other commonly reported adaptations to prolonged agonist treatment. Adenylyl cyclase superactivation was readily apparent following agonist treatment but there was no evidence of the formation of constitutively active μ-opioid receptors. This result challenges the notion that prolonged agonist exposure inevitably produces μ* receptors, and is consistent with many studies of adaptations in neurons produced by chronic agonist treatment. The investigators provide no explanation of their failure to see μ* receptors in C6 cells, but this is perhaps understandable because the molecular nature of μ* receptors remains elusive, and the precise mechanisms that lead to their formation are unknown. Without knowing exactly what μ* receptors are, how they are formed and how they signal, understanding their role in cellular adaptations to prolonged opioid treatment will remain impossible. Studies such as this should refocus attention on establishing the molecular mechanisms that underlie that phenomenon of μ* receptors.     

依那朵林的合成

对具有很高kappa受体亲和性和选择性的依那朵林进行了合成研究,以1,4-环己二酮为原料,经缩合、环合、还原,环氧化等16步反应得到关键中间体1-[8-甲氨基-1-氧杂螺[4.5]癸烷-7-基]吡咯烷（16）,再和4-苯半呋喃乙酸在偶合剂CDI催化下得到目标化合物依那朵林。     

吗啡依赖大鼠脑组织内吗啡的免疫组织化学研究

目的··：研究吗啡依赖后大鼠脑内吗啡含量变化。方法··：对慢性染吗啡大鼠脑组织内的吗啡进行了原位免疫组织化学研究。结果··：染毒７ｄ大鼠脑组织内未能检出吗啡,染毒１４ｄ大鼠脑组织内出现了强弱不一的免疫反应。结·论·：大鼠对吗啡依赖形成过程中,脑组织内吗啡含量增高,且吗啡的分布与μ阿片受体分布一致。     

非阿片类药物改善阿片类药物致呼吸抑制研究进展

阿片类药物通过作用于阿片受体,激活与受体偶联的G蛋白和(或)β-抑制蛋白等信号通路而发挥镇痛和麻醉等效应,但同时阿片类药物致呼吸抑制(OIRD)则是临床常见的严重问题.目前通常采用阿片受体拮抗剂纳洛酮等改善OIRD,但纳洛酮可能会拮抗阿片类药物的镇痛作用,甚至带来许多不可预知的不良反应.近年来,使用非阿片类药物直接和(...