Dopamine D₁- and D₂-Receptors in Immunostimulation under Activation of Mu-Opioid Receptors in Mice with Different Psychoemotional States

The purpose of the present study was to analyze the effect of activation of mu-opioid receptors (mu-OR) on the immune response under blockade of postsynaptic D1-and D2-receptors in mice of the C57BL/6J strain displaying either aggressive or depressive-like behaviors in the social conflict model. It is shown that activation of activation of mu-OR with a highly selective agonist DAGO (100 μg/kg) increased significantly IgM-immune response not only in C57BL/6J mice with an unchanged psychoemotional state but also in mice displaying aggressive or depressive-like behaviors in the social stress model (10 days of agonistic confrontations). Selective blockade of DA receptors of the D1-type with SCH-23390 (1.0 mg/kg with DAGO administration) caused a more pronounced elevation of IgM-immune response than DAGO alone while DAGO effect was completely blocked by prior administration of D2-receptor antagonist haloperidol (1.0 mg/kg). At the same time, both SCH-23390 and haloperidol prevented the immune response increase induced by DAGO injection in mice engaged in aggressive or depressive-like behaviors. Thus, in animals not subjected to social stress DAGO-induced immunostimulation is provided only by D2-receptors, whereas in animals with altered psychoemotional state mu-opioid immunostimulation is mediated by both types of DA receptors—D1 and D2. These data provide evidence for different impacts of the main subtypes of DA receptors in the mediation of immunomodulating effects of mu-opioid system under normal and stressful conditions.

Expression of mu-opioid receptors in human chronic inflamed knee joint synovium tissue

Objective: To examine the changes of mu-opioid receptors (MORs) expression in human chronic inflamed knee joint synovium tissue. Methods:Knee joint synovium tissues were taken from 21 patients with chronic arthritis (inflamed group) and 6 fresh bodies with normal knee joints (control group). And the expression of MORs was detected by using immunohistochemistry. flow cytometry(FCM) and reverse-transcription polymerase chain reaction (RT-PCR). Results: The expression of MORs in the inflamed group was significantly higher than that in the normal group by using the 3 techniques(P<0. 05). Conclusion: Chronic inflammation enhances the up-regulation of MORs in human knee joint synovium tissue.

Changes of mu and kappa opioid receptors in cathartic colon of rat

Objective: To oberve the changes of mu and kappa opioid receptors in the cathartic colon of rat, and to clarify that whether opioid receptors accounts for the occurrence of slow trait constipation (STC). Methods: The cathartiic colon model of rat was made by feeding with laxatives. The activity of mu and kappa opioid receptors in the cathartic colon of rat was measured by radio-ligand binding assay. Results: Compared with the control group, the maximal binding capacity (Bmax) and affinity(Kd) of mu opioid receptor in cathartic colon group were significantly increased (207. 00 ± 22. 90 fmol/mg·p vs 82. 00 ± 14.23 fmol/mg· p, P ＜ 0.01 ;3.30 ± 0.45 mmol/L vs 2.40 ± 0.57 mmol/L, P ＜ 0.05). The maximal binding capacity of kappa opioid receptor also showed a great increase (957. 00 ± 102. 41 fmol/mg· p vs 459.00 ± 52.41 fmol/mg·p, P ＜ 0.01 ), but no significant difference of affinity was found between the two groups. Conclsion: The mu and kappa opioid receptors may be involved in the functional disorders of cathartic colon.

YFa and analogs:Investigation of opioid receptors in smooth muscle contraction

AIM:To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity. METHODS:The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMKKKFMRF amide and Des-Phe-YGGFMKKKFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltor-phimine norBNI. RESULTS:YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with mor-phine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays. CONCLUSION:YFa revealed its side-effect-free analgesic properties with regard to arrest of gastroin-testinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.

Immunohistochemical identification of dynorphin A and Kappa opioid receptor-1 in the digestive system of scallop Chlamys farreri

Little is known about the roles of dynorphin and Kappa opioid receptor(KOR) in mollusks. In this study, we aim to determine the distribution of dynorphin A and KOR-1 in the digestive system of the scallop Chlamys farreri. Using immunohistochemical staining, we confirmed the expression of dynorphin A and KOR-1 in the digestive system of C. farreri. Dynorphin A immunopositive cells were identified in intestine and hepatopancreas. In intestine, small and spherical dynorphin A immunopositive cells(4–9 μm in diameter) were scattered among the long columnar epithelial cells(ECs). In hepatopancreas, cells containing masses(5–14 μm in diameter) of dynorphin A immunopositive products were observed in epithelium of acinis. These immunopositive cells may be synthetic and/or secretory cells of dynorphin A. Dynorphin A immunoreactive products were commonly observed in epithelium and connective tissue(CT) of labial palps, mouth labia and stomach, which presented in forms of grains, fibers or flakes. KOR-1 immunoreactive material was observed in ECs and CTs of labial palps, mouth labia and stomach, intestine and hepatopancreas. The distribution of both dynorphin A and KOR-1 in the digestive organs suggests an involvement of dynorphin via KOR-1 in the functional regulation of the digestive system of C. farreri.

Analgesic and anti-inflammatory potential of aerial parts of the Daphne mucronata Royle extract in mice: Opioid-independent action

Objective: To investigate the analgesic and anti-inflammatory property and possible involvement of opioid receptors of ethyl acetate extract from aerial parts of Daphne mucronata(D. mucronata) in mice by formalin test.Methods: Single doses of 2.5, 5.0 and 10.0 mg/kg of body weight of ethyl acetate extract of D. mucronata were intraperitoneally administered to the mice 30 min before analgesic test. The anti-nociceptive effect of preparations was evaluated based on the formalin in mice.Results: The results indicated that the extract(2.5, 5.0 and 10.0 mg/kg) increased the pain threshold of mice and induced analgesia in both phases of formalin test. Like morphine sulfate(5.0 mg/kg, i.p.), the extract also showed more effective analgesic effect on the late phase of formalin test. Pre-treatment of animals with naloxone(5.0 mg/kg i.p.)did not inhibit the effects of the extract.Conclusions: Our findings suggest that D. mucronata contains potential analgesic and anti-inflammatory compounds which support its traditional use. Moreover, it seems that the analgesic and anti-inflammatory effects of the extract is mediated by non-opioid mechanisms. Further pharmacological studies are required to determine whether the analgesic mechanisms are actually responsible for such properties.

Effects of Peripherally Acting Opioid Ligands on Central Opioid Receptors and <i>β</i>-Endorphin Release in Stressed Rats

Using the radioreceptor binding assay, μ-opioid receptor (MOR) affinity in the midbrain of stressed rats was higher than in naive controls. MOR density in the rat frontal cortex was reduced after stress. Intragastric administration of the MOR antagonist naloxone methiodide was followed by an increase in the number of MORs in the frontal cortex. However, the MOR agonist loperamide significantly decreased the density of MORs in the frontal cortex and midbrain of naive animals. Loperamide and naloxone methiodide were shown to prevent an increase in MOR affinity and a decrease in MOR density in the midbrain of rats after restraint stress. The restraint stress was accompanied by an increase in the release of β-endorphin (BE) in the ventral tegmental area (VTA) of control rats. After administration, loperamide slightly decreased the release of BE, naloxone methiodide significantly increased the release of BE in the cingulate cortex (CC) of untreated animals, while drugs had no effect on the release of BE in the VTA. The drugs significantly increased the extracellular level of BE in the CC of stressed animals. Loperamide abolished the increase in the stress-induced release of BE in the VTA. By contrast, naloxone methiodide significantly increased the release of BE in the VTA of stressed rats. Our data indicated that activation of peripheral MORs induces depression of the central part of the μ-opioid system, but suppression of peripheral MOR activity induces activation of the central μ-opioid system, the interaction of which can be modulated by stress.

Low-dose morphine elicits ventilatory excitant and depressant responses in conscious rats: Role of peripheral <i>µ</i>-opioid receptors

The systemic administration of morphine affects ventilation via a mixture of central and peripheral actions. The aims of this study were to characterize the ventilatory responses elicited by a low dose of morphine in conscious rats;to determine whether tolerance develops to these responses;and to determine the potential roles of peripheral μ-opioid receptors (μ-ORs) in these responses. Ventilatory parameters were monitored via unrestrained whole-body plethysmography. Conscious male Sprague-Dawley rats received an intravenous injection of vehicle or the peripherally-restricted μ-OR antagonist, naloxone methiodide (NLXmi), and then three successive injections of morphine (1 mg/kg) given 30 min apart. The first injection of morphine in vehicle-treated rats elicited an array of ventilatory excitant (i.e., increases in frequency of breathing, minute volume, respiratory drive, peak inspiratory and expiratory flows, accompanied by decreases in inspiratory time and end inspiratory pause) and inhibitory (i.e., a decrease in tidal volume and an increase in expiratory time) responses. Subsequent injections of morphine elicited progressively and substantially smaller responses. The pattern of ventilatory responses elicited by the first injection of morphine was substantially affected by pretreatment with NLXmi whereas NLXmi minimally affected the development of tolerance to these responses. Low-dose morphine elicits an array of ventilatory excitant and depressant effects in conscious rats that are subject to the development of tolerance. Many of these initial actions of morphine appear to involve activation of peripheral μ-ORs whereas the development of tolerance to these responses does not.

Corelation Between Single Nucleotide Polymorphisms in Mu Opioid Receptor Exon 2 and Stereotypic Behaviour in Sows

Three breeds of sows were observed to investigate the relationship between Single Nucleotide Polymorphisms（SNPs） in Mu Opioid Receptor（MOR）and stereotypic behaviour,such as,sham-chewing,bar biting and standing still in order to better understand the mechanism of stereotypic development of the animals in restrained conditions.MOR exon 2 partial sequences were amplified to analyze single nucleotide polymorphisms by PCR-SSCP.One SNP,a silence mutant was found.A significant difference （P〈0.01）was found in the frequency of genotypes in these 3 breeds where only the BB genotype,which was identical to that published in GenBank,was found in the Duroc breed,while no AA genotype was found in Landrace,3 genotypes AA,BB and AB were found in Yorkshire.The result also indicated that the individuals with AA and AB genotypes tended to be more active in sham-chewing than those with the BB genotype（P〈0.05）.The overall results of this study suggested that sham-chewing of sows may be subjected to both genetic control and environmental conditions,but activity level was more likely to be affected by their environment.We can putatively draw the conclusion that MOR gene has effect on the sham-chewing behavioral traits of sow.

Determination of structure-activity relationships between fentanyl analogs and human μ-opioid receptors based on active binding site models

Fentanyl is a potent and widely used clinical narcotic analgesic, as well as a highly selective IJ-opioid agonist. The present study established a homologous model of the human μ-opioid receptor; an intercomparison of three types of μ-opioid receptor protein sequence homologous rates was made. The secondary receptor structure was predicted, the model reliability was assessed and verified using the Ramachandran plot and ProTab analysis. The predictive ability of the CoMFA model was further validated using an external test set. Using the Surflex-Dock program, a series of fentanyl analog molecules were docked to the receptor, the calculation results from Biopolymer/SitelD showed that the receptor had a deep binding area situated in the extracellular side of the transmembrane domains （TM） among TM3, TM5, TM6, and TMT. Results suggested that there might be 5 active areas in the receptor. The important residues were Asp147, Tyr148, and Tyr149 in TM3, Trp293, and His297 in TM6, and Trp318, His319, Ile322, and Tyr326 in TM7, which were located at the 5 active areas. The best fentanyl docking orientation position was the piperidine ring, which was nearly perpendicular to the membrane surface in the 7 TM domains. Molecular dynamic simulations were applied to evaluate potential relationships between ligand conformation and fentanyl substitution.

Subtype of Opioid Receptor in Airway SmoothMuscle and the Role of the Receptor in Asthmatic Attacks

In order to elucidate the behavior of opioid receptor in the airway smooth muscle (ASM) and potential role of the receptor in asthmatic attacks electrical field stimulation (EFS) was used to evaluate the effects of different narcotics and naloxine (Nal) on isolated rabbit ASM and biochemical methods were used to assay the influences of morphine (Mor) and pethidine(Pet) on the activities of adenylcyclase (AAC) and phosphodiesterase(APDE) in homogenate derived from rabbit ASM.Nal was used to treat the bronchospasm during anesthesia. It shows that Mor increased the rabbit ASM contraction and Nal reversed this effect, while Nal itself did not affect ASM. Fentanyl(Fen) decreased the contraction and Pet not only decreased the contraction but relaxed the ASM. Mor decreased the AAC in the rabbit ASM but didn't affect the APDE in the rabbit ASM. Pet had no influence on both the AAC and the APDE. Nal effectively relieved the bronchospasm which failed to the traditional treatment during anesthsia. These indicate that the opioid receptor in the ASM is a new subtype one.Mor exhibits satuable binding the subtype receptor and exerts strong agonistic activity to induce bronchospasm, while Nal antagonizes this effect. Yet Fen and Pet don's bind this subtype receptor. Endogenous opioid-like peptides may also bind this subtype receptor. In patients with airway hyperreactivity (PAHR) Mor is contraindicated, Fen and Pet may be used. and the latter may be the best choice.Asthma or bronchospasm may be treated with Nal.

Opiate-induced constipation related to activation of small intestine opioid μ2-receptors

AIM:To investigate the role of opioid μ-receptor subtype in opiate-induced constipation (OIC).METHODS:The effect of loperamide on intestinal transit was investigated in mice.Ileum strips were isolated from 12-wk-old male BALB/c mice for identification of isometric tension.The ileum strips were precontracted with 1 μmol/L acetylcholine (ACh).Then,decrease in muscle tone (relaxation) was characterized after cumulative administration of 0.1-10 μmol/L loperamide into the organ bath,for a concentration-dependent study.Specific blockers or antagonists were used for pretreatment to compare the changes in loperamide-induced relaxation.RESULTS:In addition to the delay in intestinal transit,loperamide produced a marked relaxation in isolated ileum precontracted with ACh,in a dose-dependent manner.This relaxation was abolished by cyprodime,a selective opioid μ-receptor antagonist,but not modified by naloxonazine at a dose sufficient to block opioid μ-1 receptors.Also,treatment with opioid μ-1 receptor agonist failed to modify the muscle tone.Moreover,the relaxation by loperamide was attenuated by glibenclamide at a dose sufficient to block ATP-sensitive K + (K ATP) channels,and by protein kinase A (PKA) inhibitor,but was enhanced by an inhibitor of phosphodiesterase for cyclic adenosine monophosphate (cAMP).CONCLUSION:Loperamide induces intestinal relaxation by activation of opioid μ-2 receptors via the cAMPPKA pathway to open K ATP channels,relates to OIC.

RNA interference targeting mu-opioid receptors reverses the inhibition of fentanyl on glucose-evoked insulin release of rat islets

Background Mu opioid receptor plays an important role in many physiological functions. Fentanyl is a widely used opioid receptor agonist for analgesia. This study was conducted to test the role of mu-opioid receptor on insulin release by determining whether fentanyl affected insulin release from freshly isolated rat pancreatic islets and if small interfering RNAs （siRNA） targeting mu-opioid receptor in the islets could knock down mu-opioid receptor expression.Methods Islets were isolated from ripe SD rats＇ pancreas by common bile duct intraductal collagenase V digestion and purified by discontinuous Ficoll density gradient centrifugation. The siRNA knock-down of mu-opioid receptor mRNA and protein in islet cells was analyzed by semi-quantitative real time-PCR and Western blotting. After siRNA-transfection for 48 hours, the islets were co-cultured with fentanyl as follows： 0 ng/ml, 3 ng/ml and 30 ng/ml for 48 hours. Then glucose-evoked insulin release was performed. As a control, the insulin release was also analyzed in islets without siRNA-trasfection after being co-cultured with fentanyl for 48 hours.Results After 48 hours of transfections, specific siRNA targeting of mu-opioid receptors produced significant reduction of mu-opioid receptor mRNA and protein （P ＜0.01）. Fentanyl significantly inhibited glucose-evoked insulin release in islets in a concentration dependent manner （P ＜0.01）. But after siRNA-transfection for 48 hours, the inhibition on glucose-evoked insulin reiease was reversed （P ＜0.01）.Conclusions RNA interference specifically reduces mu-opioid receptor mRNA and protein expression, leading to reversal of the fentanyl-induced inhibition on glucose-evoked insulin release of rat islets. The activation of opioid receptor induced by fentanyl functions to inhibit insulin release. The use of RNAi presents a promising tool for future research in diabetic mechanisms and a novel therapy for diabetes.

EFFECT OF ELECTROACUPUNCTURE ON THE IMMUNOREACTIVITY OF FOCAL CUTANEOUS μ-OPIOID RECEPTOR IMMUNOREACTION-POSITIVE FIBERS IN ADJUVANT ARTHRITIC RATS

客观：学习 -opioid 的效果在煽动性的皮肤织物和 electroacupuncture (EA ) 的效果的受体(粗腐殖质) 表示在在助手的粗腐殖质积极纤维的热门免疫反应(红外) 关节炎(AA ) 老鼠。方法：48 只 SD 老鼠的一个总数被使随机化进控制(n =8 ) ，模型(n= 10 ) ， focus-side-EA (n = 10 ) ， non-acupoint-EA (n = 10 ) ，并且 healthy-side-EA (n = 10 ) 组。 AA 模型被完全的 Freund 的助手的下的注射建立( CFA ， 50 L )进左后部的 paw.EA ( 4-16 Hz ， 0.5-1.5 V )为 30 min 在焦点或健康方面和 non-acupoints 上被用于“ Huantiao ”( GB 30 )和“ Yanglingquan ”( GB 34 )。使用的 Non-acupoints 是二个地点 5 公里到健康方面上的 GB 30 和 GB 34。在焦点的真皮、下的纸巾的热门粗腐殖质红外积极的纤维与 immunohistochemical 方法被染色。疼痛的严厉被把测试弄弯的脚(anklejoint ) 检测。结果：与模型组相比，“弯曲脚的测试” 20 在 第9 和 第11 天( P0.05 )并且在 non-acupoint-EA 组在 focus-side-EA 组显著地减少了在上 第8 ， 第9 并且在 CFA ( P 0.05 )的注射以后的 11thd ，都显示双边的 GB 30 和 GB 34 和 non-acupoints 的那 EA 能减轻疼痛。从第 13 天在上，没有重要差别在 3 个 EA 组和模型组(P0.05 ) 之中在“弯曲脚的测试”被发现分数。与控制组比较，在焦点织物的粗腐殖质红外积极的神经纤维的区域价值在在在模型的焦点的粗腐殖质红外积极的神经纤维的 .The 区域价值组织的 3 个 EA 组( P0.05 )是显著地更高的， 3 个 EA 组在控制组( P0.05 )比那高重要。与模型组相比，区域在组和 healthy-side-EA 组显著地增加了的 focus-side-EA (P 0.05 ) 粗腐殖质红外积极的纤维珍视；当在 non-acupoint-EA 组和 healthy-side-EA 组的粗腐殖质红外积极的纤维的那些在 focus-side-EA 是比那显著地低的时，组( P 0.05 )，和没有重要差别在粗腐殖质红外积极的纤维( P0.05 )的区域在模型组， healthy-side-EA 组和 non-acupoint-EA 组之中被发现，在焦点方面上显示 acupoints 的 EA 的更强壮的效果。结论：GB 30 和 GB 34 的 EA 能减轻煽动性的疼痛和起来调整在在 AA 老鼠的焦点的皮纸巾的粗腐殖质红外积极的纤维的表示，施加反煽动性、止痛的效果。

猪Mu阿片受体基因单核苷酸多态性分析

Mu阿片受体(简称MOR)属于G蛋白藕联受体,分布在痛觉传导区,以及与情绪和行为有关的区域,影响动物的神经反应和行为表现。该研究以长白猪、大白猪和杜洛克猪为试验材料,用8对引物对Mu阿片受体基因的5′UTR区域、整个编码区和3′UTR区域用PCR SSCP方法进行了扫描,发现5处突变基因座(GenBank登录号:AF521309)。统计结果发现基因型频率分布与品种有关,大白猪突变基因型频率显著高于长白和杜洛克,本研究推测分布上的差异可能是由于长期的选择压力造成的。

海马mu型阿片肽受体介导大鼠癫痫发作敏感性形成(英文)

为探讨海马mu型阿片肽受体介导癫痫发作敏感性形成的作用,实验采用微渗透泵技术,观察大鼠腹侧海马注射mu型阿片肽受体激动剂PL017(2.09、2.59、3.29 μg/μl)、拮抗剂β-funaltrexamine hydrochloride(β-FNA、0.88、1.10、1.35μg/μl)对红藻氨酸(kainic acid,KA)诱导癫痫发作的干预作用。PL017能够明显缩短癫痫发作潜伏期、增加癫痫发作级别(P<0.05),β—FNA则可显著延长癫痫发作潜伏期、降低发作级别(P<0.01);PL017和β-VNA的干预作用均表现出剂量依赖效应。结果表明,海码mu型阿片肽受体具有促进KA诱导的癫痫发作敏感性形成作用。

Mu阿片受体多态性与海洛因依赖的关联研究

目的:探讨上海汉族人群中Mu阿片受体(OPRM1)基因A118G位点、C1031G位点多态性与海洛因依赖关联性。方法:采用病例对照研究,分别检测201名海洛因依赖者(依赖组)和249名健康对照(对照组)OPRM1基因A118G和C1031G位点基因型及等位基因频率,分析海洛因依赖者OPRM1受体基因多态与物质依赖的相关性。结果:A118G和C1031G位点多态性在依赖组和对照组间的分布差异无显著性;单体型分析两位点4种单体型均与海洛因依赖间无关联。结论:OPRM1基因A118G和C1031G位点与海洛因依赖无显著相关性。

Mu阿片受体在大鼠“泻剂结肠”肠道低反应中的作用

目的 研究mu阿片受体对“泻剂结肠”大鼠结肠动力的影响 ,“泻剂结肠”大鼠肠道阿片受体含量的变化。方法 以“泻剂结肠”为模型 ,用电刺激离体肌条收缩反应试验、放射性配体结合等方法。结果 外源性增加DAMGO明显抑制电刺激“泻剂结肠”大鼠离体肌体收缩反应 ,收缩波振幅降低 ,这种抑制作用是剂量相关 ,mu阿片受体拮抗剂Naloxone明显加强电刺激“泻剂结肠”大鼠离体肌条收缩反应 ,收缩波振增加 ,与正常组相比 ,“泻剂结肠”大鼠肠道mu阿片受体含量增加。结论 内源性阿片肽通过阿片受体介导参与了慢传输性便秘肠道动力的调控 。

Mu-、kappa-、delta-阿片受体在成年大鼠正常胃组织的免疫组织化学定位研究

目的观察mu-、kappa-、delta-阿片受体在成年大鼠正常胃组织中的分布与定位。方法选用成年雄性wistar大鼠胃组织切片进行免疫组织化学染色,用免疫组织化学技术对Mu-、kappa-、delta-阿片受体在大鼠胃组织的分布进行定位分析。结果mu-阿片受体免疫阳性物质主要分布于胃黏膜上皮及黏液层、胃主细胞、肌间神经丛等部位;kappa-、delta-阿片受体免疫阳性物质主要分布于胃主细胞、肌间神经丛等部位。结论mu-、kappa-、delta-阿片受体在胃主细胞膜和胞浆、肌间神经丛等部位均有分布,但仅mu-阿片受体还存在于胃黏膜上皮及黏液层,提示阿片受体参与了胃各种生物学功能及胃粘膜的损伤、修复与再生。