小鼠脾脏淋巴细胞上存在μ阿片受体的证据(英文)

目的:用高亲和性μ阿片受体激动剂羟甲芬太尼研究小鼠脾脏淋巴细胞是否存在阿片受体。方法:观察羟甲芬太尼(Ohm)对脾脏淋巴细胞体外增殖的影响及纳络酮的阻断作用;采用[~3H]Ohm放射配体分析法检测小鼠脾脏淋巴细胞上的阿片受体。结果:Ohm 0.1pmol·L~(-1)-1nmol·L~(-1)增加Con A诱导的T-淋巴细胞增殖,这种增殖作用可以被纳络酮阻断。Ohm不能促进LPS诱导的B-细胞增殖。Ohm 0.1-1μmol·L~(-1)能够抑制活化的淋巴细胞增殖。这种抑制作用不被纳络酮阻断,[~3H]Ohm与淋巴细胞阿片受体的结合具有特异性、饱和性、可逆性。结论:Ohm对静止及活化的T-细胞的促增殖作用是由阿片受体介导的。小鼠脾脏淋巴细胞上存在阿片受体。     

μ阿片受体及其与羧甲芬太尼相互作用的分子模拟

建立μ阿片受体的结构模型，并结合模型研究羧甲芬太尼对该受体的作用机制。以细菌视紫红质的三维结构为模板，在计算机上建立μ阿片受体模型，然后将羟甲芬太尼对接到假想的受体结合部位。得到了良好的配体－受体相互作用模型，发现残基Ａｓｐ１４７与Ｈｉｓ３１９为可能的结合位点。     

μ阿片受体及受体—配基相互作用的分子模拟

目的：构建μ阿片受体（μＯＲ）的三维结构模型并研究它与芬太尼衍生物的相互作用。方法：以细菌视紫红南为模板，模拟μＯＲ的三维结构。然后蒋芬太尼衍生物对接到μＯＲ的七个α螺旋束之内，并计算结合能，结果：（１）得以受体－配基作用模型．（２）模型中，基本结合位点可能是Ａｓｐ１７和Ｈｉｓ２９７，Ａｓｐ１４７与配基的正电性能铵基形成强的静电和氢键相互作用，这种作用在Ｈｉｓ２９７和配基的羰基Ｏ原子之间较弱，（３     

阿片受体及其配体

阿片类药物的镇痛与成瘾机制近年来的研究进展迅速。目前 ,人们已发现 μ、δ、κ、ＯＲＬ１、ε、σ、λ、ι和ζ９种阿片受体 ,且每种受体均有不同的亚型。在这９种受体中 ,研究最多的是 μ、δ、κ、ＯＲＬ１ ,本文根据国内外研究成果及最新研究进展 ,从分子生物学与分子药理学的角度就 μ、δ、κ、ＯＲＬ１阿片受体的情况做一简单介绍。１ μ-受体１９９３年 ,Ｗａｎｇ［１］等报道成功克隆了 μ-受体 ,到２０００年已发现７种 μ-受体亚型 ［２］ ,它们是ＭＯＲ -１的１０个外显子多种组合形成的。其组成结构分别为ＭＯＲ -１(外显子…     

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。     

μ阿片受体C末端相互作用蛋白筛选及功能研究

目的：MOR细胞内的磷酸化位点主要位于C-末端，本研究筛选细胞内与MOR的C末端有直接相互作用的蛋白，以研究其对MOR磷酸化、内吞、脱敏及复敏等过程的影响。方法：BaeterioMateh 细菌双杂交，为新发展起来研究蛋白与蛋白之间相互作用有效方法。PCR法扩增目的片断，双酶切后与载体连接。Western Blot验证蛋白表达。结果：以大鼠MOR（rMOR）cDNA为模板，PCR扩增C末端（末端340—398氨基酸）作为诱饵融合于pBT载体的入阻遏蛋白（λcI）上，命名pBT—C。Western Blot证明该诱饵蛋白表达正确。大鼠脑cDNA文库融合到pTRG载体的RNA多聚酶的α亚单位的N末端。两种重组质粒共同转入Screening Reporter报告菌后接种于选择性筛选培养基。共筛选得到154个克隆，通过双选筛选平板进一步确证为124个克隆。将双选得到的克隆与诱饵质粒分离，诱饵与阳性克隆两两共转在选择性培养基上再筛选以验证此克隆确实依赖于蛋白间的相互作用，排除自身激活作用。二次筛选确证19个阳性克隆，部分测序结果显示阳性克隆包括代谢相关氧化还原酶、肌动微管微丝形成相关蛋白、参与蛋白磷酸化的蛋白、热休克蛋白以及保守的跨膜受体等。结论：MOR的C-末端除了与蛋白激酶相互作用外，还与细胞内其他蛋白有相互作用。这就提示依赖与耐受的形成过程中可能有其他蛋白参与。     

Analgesic potency of TRIMU-5: a mixed mu 2 opioid receptor agonist/mu 1 opioid receptor antagonist.

TRIMU-5 (Tyr-D-Ala-Gly-NH-(CH2)2CH(CH3)2) is a potent enkephalin analog with analgesic actions. Detailed studies show high affinity for both mu 1 and mu 2 sites, with poor affinity for delta, kappa 1 and kappa 3 receptors. Of all the mu ligands examined in binding assays, TRIMU-5 was the most mu-selective. In mice, TRIMU-5 administered either intracerebroventricularly (i.c.v.) or intrathecally elicited analgesia which was readily reversed by the mu-selective antagonist beta-funaltrexamine (beta-FNA). However, the analgesia observed following i.c.v. injections differed from traditional mu ligands: (1) the dose of drug required for analgesic activity i.c.v. was 100-fold greater than those following intrathecal administration; (2) although sensitive to beta-FNA, the analgesia was not antagonized by naloxonazine; and (3) the analgesia was reversed by an opioid antagonist given intrathecally (i.t.) but not i.c.v. Thus, TRIMU-5 analgesia appeared to be mediated spinally through mu 2 receptors. TRIMU-5 did have supraspinal actions, inhibiting gastrointestinal transit, another mu 2 action. In binding studies TRIMU-5 had high affinity for mu 1 sites, but pharmacological studies revealed antagonist actions at this receptor. In mice, the analgesia produced by morphine given i.c.v. was antagonized by coinjection of a low TRIMU-5 dose which was inactive alone. Similarly, TRIMU-5 coadministered with morphine into the periaqueductal gray of rats reversed the analgesia seen with morphine alone. Thus, TRIMU-5 is a highly selective mixed mu 2 opioid receptor agonist/mu 1 opioid receptor antagonist.     

Effect of opioid receptor ligands on the mu-S196A knock-in and mu knockout mouse vas deferens

We have determined the effect of naltrexone, naloxone, [D-Ala2,D-Leu5]enkephalin (DADLE), and morphine on the mu-S196A opioid receptor knock-in and mu-opioid receptor knockout mouse vas deferens preparations. The antagonists, naltrexone and naloxone, exhibited agonist activity and possessed IC50 values that were 14- and 37-fold greater than morphine on the S196A preparation. Morphine was found to be threefold more potent at S196A relative to wild-type mu-opioid receptor. The mouse vas deferens data suggest that S196 in transmembrane helix 4 of the mu-opioid receptor modulates efficacy. It is proposed that this may be due to decreased dimerization of the receptor. Identical IC50 values of DADLE obtained on the wild-type, S196A knock-in, and mu-opioid receptor knockout preparations support the absence of mu-delta heterodimers in the mouse vas deferens.     

Evidence for differential opioid mu 1- and mu 2-receptor-mediated regulation of heart rate in the conscious rat.

The possibility that mu-opioid-induced tachycardia and bradycardia could be mediated by different subtypes of the mu-receptor was studied in conscious Sprague-Dawley rats. The selective mu-receptor agonist dermorphin and its analog, TAPS (Tyr-D-Arg-Phe-sarcosine), a putative mu 1-receptor agonist, were given centrally. Tyr-D-Arg-Phe-sarcosine increased the heart rate, the response being inversely correlated to the dose (an increase of 71 +/- 22, 49 +/- 14 and 30 +/- 17 beats/min at doses of 0.3, 3 and 30 pmol, respectively). Dermorphin induced less clear changes in heart rate (maximum increase of 39 +/- 14 beats/min at the dose of 1 pmol). After treatment with the mu 1-selective antagonist naloxonazine (NAZ), TAPS 30 pmol and dermorphin 1 pmol decreased heart rate by -22 +/- 10 and -24 +/- 7 bpm, respectively. The bradycardiac effect of larger doses of dermorphin was potentiated by NAZ (from -25 +/- 8 to -97 +/- 22 bpm) but abolished by the non-selective antagonist naloxone. These data suggest that the high affinity mu 1-opioid receptors mediate tachycardic responses and mu 2-receptors mediate bradycardic responses.     

Current strategies toward safer mu opioid receptor drugs for pain management

Introduction: Pain relief remains a major public health challenge. The most efficient available painkillers are opioids targeting the mu opioid receptor (MOR). MORs are expressed in the areas of the brain [including pain and respiratory centers] that are important for processing reward and aversion. Thus, MOR activation efficiently alleviates severe pain, but the concomitant reward and respiratory depressant effects pose a threat; patients taking opioids potentially develop opioid addiction and high risk for overdose.

Areas covered: Ongoing efforts to generate safer opioid analgesics are reviewed here. The design of biased compounds that trigger MOR induced G protein over β-arrestin signaling, peripheral opioids, drugs targeting MORs in heteromers and drugs enhancing endogenous opioid activity are discussed.

Expert opinion: There is evidence that throttling MOR signaling may lead to an era of opioids that are truly efficient painkillers with lower side effects and risk of overdose. However, few of the drugs derived from the advanced approaches outlined here, are getting approval by regulatory committees for use in clinical settings. Thus, there is an urgent need to (i) better clarify mechanisms underlying the hazardous physiological effects of MOR activation, and (ii) fully validate the safety of these new MOR-based therapies.     

Neoclerodane diterpenes as a novel scaffold for mu opioid receptor ligands

Structural modification of salvinorin A, the active component of Salvia divinorum, has resulted in the synthesis of novel neoclerodane diterpenes with opioid receptor affinity and activity. We report in this study a nonnitrogenous neoclerodane diterpene with mu opioid receptor affinity (13) that is an agonist at mu opioid receptors. This represents the identification of a novel structural class of mu opioid receptor agonists.     

P-8502--a new mu selective opioid receptor ligand

The analgesic potencies of 3-[beta-(p-amino)-phenethyl)-9 beta-methoxy-9 alpha-(m-methoxyphenyl)-3- azabicyclo [3,3,1] nonane (P-8502) and 3-[beta-(p-monoester fumarylamido)-phenethyl]-9 beta-methoxy-9 alpha-(m-methoxyphenyl)-3-azabicyclo [3,3,1] nonane (P-8511) were examined. The analgesic ED50 of P-8502 and P-8511 were 55 and 200 micrograms/kg (mice, ip, hot plate), and 30 and 95 micrograms/kg (rat, sc, tail flick), respectively. The duration of the analgesic action of P-8511 (about 4 h) was longer than that of P-8502 (about 1.5 h, rat, sc, tail flick). Binding assay showed that P-8502 had a high ratio of delta/mu, kappa/mu: IC50 (DPDPE)/IC50 (DAGO) = 399; IC50(DAD-LE)/IC50 (DAGO) = 1498; IC50 (kappa)/IC50 (DAGO) = 159. In conclusion, P-8502 appears to be a new mu selective opioid receptor ligand, whereas P-8511 has no such selectivity.     

Transcriptional regulation of mu opioid receptor gene by cAMP pathway

The utility of morphine for the treatment of chronic pain is hindered by the development of tolerance. Fentanyl has been shown to be a potent analgesic with a lower propensity to produce tolerance and physical dependence in the clinical setting. Previous finding has shown that fentanyl induces mu opioid receptor gene expression in PC-12 cells (Brain Res 859:217-223, 2000). In this report, we aim to identify the molecular mechanism of mu-opioid receptor (MOR) gene regulation by fentanyl. We demonstrated that the 4.7-kilobase MOR promoter could be induced by fentanyl in PC-12 cells, and we defined a partial cAMP response element (CRE) located at -106/-111 in 5'-untranslated region of the MOR gene. In electrophoretic mobility shift assay, cAMP response element-binding protein (CREB) was found in the protein-DNA complex formed on the CRE box. CREB was phosphorylated after forskolin induction, and both CREB and CREB-binding protein (CBP) binding to the endogenous MOR promoter was increased by forskolin in chromatin immunoprecipitation assay. The functional role of CREB in the induction of MOR gene was further elucidated by an experiment in which a dominant-negative mutant CREB, CREB-S133A, abolished the forskolin-mediated MOR induction. Moreover, we found that this CRE box is conserved in mouse, rat, and human MOR gene, implying physiological relevance in different species. Collectively, this study demonstrated that fentanyl-triggered MOR gene induction was mediated by the sequential activation of CREB and the binding of CREB and CBP to MOR promoter, thus provides direct evidence for lower propensity of fentanyl to produce tolerance.