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 displayi...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.展开更多
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 (...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.展开更多
Objective: To observe 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 transit constipation (STC). Methods: T...Objective: To observe 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 transit constipation (STC). Methods: The cathartic 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. Conclusion: The mu and kappa opioid receptors may be involved in the functional disorders of cathartic colon.展开更多
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...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.展开更多
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 farr...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.展开更多
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...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.展开更多
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...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.展开更多
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 ...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.展开更多
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 sti...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.展开更多
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 o...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.展开更多
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 di...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.展开更多
The present study was designed to investigate the effects of intravenously administered agonists and antagonists at μ(DAMGO, naloxone,)δ1 (DPDPE,BNTX)andδ2(DELT, NTB)opioid receptors on the Aδ-and C-fiber evoked r...The present study was designed to investigate the effects of intravenously administered agonists and antagonists at μ(DAMGO, naloxone,)δ1 (DPDPE,BNTX)andδ2(DELT, NTB)opioid receptors on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla.Extracellular single unit recording were made from 70 nociceptive neurons(28 NS,42 WDR) in the superficial dorsal horn and 37 nociceptive neurons(4 NS,33 WDR)in the deeper dorsal horn.All these neurons had an ipsilateral orofacial mechanoreceptive field and majority of these neurons had no spontaneous activity. The latencies for the C fiber evoked responses ranged from 34~105 msec whereas for Aδfiber-evoked responses it ranged from 3~22msec. A clear separation was observed between early and late responses of evoked by Cand Aδ-fiber.Application of DPDPE,DELT and DAMGO produced inhibitory effects on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and thedeeper dorsal horn.By comparison,the inhibition was more pronounced on the C-fiber evoked response than on the Aδ-fiber evoked response,and DAMGO produced a stronger inhibitory action than both DELT and DPDPE. Additionally,DPDPE produced facilitation, or inhibition followed by facilitation on the Aδ-and C-response and the effect had longer latency and longer time course.DPDPE also induced completely oppsite effects on the Aδ-and C-fiber evoked responses.Although the facilitation was observed,the effect was not dose-dependent. Application of BNTX (0.4~1mg/kg),a δ1 receptor antagonist,produced antagonism of DPDPE in 88%(7/8) neurons. Application of the doses (0.7~1mg/kg) of BTB,δ2-receptor antagonist,resulted in antagonism of both DELT and DPDPE. The inhibition of DELT on Aδ-response was antagonized by doses (0.3~1mg/kg)of NTB in 100% (14/14)neurons while the antagonism on C-response was in 79%(11/14) neurons.The effect produced by DPDPE was antagonized by the doses (0.7~1mg/kg) of NTB in 100%(4/4) neurons. However,a smaller dose of NTB(0.3mg/kg)which and antagonize the effect of DELT,did not antagonize the effect of DPEPE in 100%(4/4) neurons. The inhibitory action of DAMGO on Aδ-and C-fiber evoked responses was completely antagonized by naloxone(0. 2mg/kg) in 100% (6/6) neurons. These results suggest that:①μ-and δ-opioid receptors play an important role in modulating Aδ-and Cfiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla; ② The inhibitory action produced by DPDPE, DELT and DAMGO was more pronounced on the C-fiber evoked excitation and indicates that the agonists produce more predominant inhibition on the responses of dorsal horn neurons to noxious stimuli; ③ activation of either δ1-orδ2-opioid receptors produces inhibitory actions on Aδ- and C-response of nociceptive neurons in the superficial and the deeper dorsal horn of the medullal;DPDPE and DELT act at different δ-opioid receptor subtypes in the rat rnedulla; ⑤i.v.-administered NTB can distinguish δ-opioid receptor subtypes in a limited dose range.When administered i. v., 0. 3mg/kg of NTB is selective for δ2-opioid receptor.展开更多
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 o...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.展开更多
Protein to protein interactions leading to homo/heteromerization of receptor is well documented in literature. These interactions leading to dimeric/oligomers formation of receptors are known to modulate their functio...Protein to protein interactions leading to homo/heteromerization of receptor is well documented in literature. These interactions leading to dimeric/oligomers formation of receptors are known to modulate their function, particularly in case of G-protein coupled receptors. The opioid receptor heteromers having changed pharmacological properties than the constituent protomers provides preferences for novel drug targets that could lead to potential analgesicactivity devoid of tolerance and physical dependence. Heterodimerization of opioid receptors appears to generate novel binding properties with improved specificity and lack of side effects. Further the molecules which can interact simultaneously to both the protomers of the heteromer, or to both the binding sites(orthosteric and allosteric) of a receptor protein could be potential therapeutic molecules. This review highlights the recent advancements in exploring the plausible role of heteromerization of opioid receptors in induction of tolerance free antinociception.展开更多
Spinal cord stimulation(SCS)-induced analgesia was characterized,and its underlying mechanisms were examined in a spared nerve injury model of neuropathic pain in rats.The analgesic effect of SCS with moderate mechani...Spinal cord stimulation(SCS)-induced analgesia was characterized,and its underlying mechanisms were examined in a spared nerve injury model of neuropathic pain in rats.The analgesic effect of SCS with moderate mechanical hypersensitivity was increased with increasing stimulation intensity between the 20%and 80%motor thresholds.Various frequencies(2,15,50,100,10000 Hz,and 2/100 Hz dense-dispersed)of SCS were similarly effective.SCS-induced analgesia was maintained without tolerance within 24 h of continuous stimulation.SCS at 2 Hz significantly increased methionine enkephalin content in the cerebrospinal fluid.The analgesic effect of 2 Hz was abolished byμorκopioid receptor antagonist.The effect of 100 Hz was prevented by aκantagonist,and that of 10 kHz was blocked by any of theμ,δ,orκreceptor antagonists,suggesting that the analgesic effect of SCS at different frequencies is mediated by different endorphins and opioid receptors.展开更多
文摘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.
基金Supported by Science and Research Foundation of Shanghai Municipal Health Bureau (200537103)
文摘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.
文摘Objective: To observe 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 transit constipation (STC). Methods: The cathartic 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. Conclusion: The mu and kappa opioid receptors may be involved in the functional disorders of cathartic colon.
基金Supported by Council of Scientific and Industrial Research,Delhi
文摘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.
基金Supported by the Natural Science Foundation of Shandong Province,China(No.ZR2012CM004)the National Natural Science Foundation of China(No.41506190)
文摘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.
基金supported by a Pharmaceutical Sciences Branch, Islamic Azad University (IAUPS) Grant
文摘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.
文摘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.
文摘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.
基金Supported by National Natural Sciences Foundation of China(39970533)
文摘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.
基金supported by the National Natural Science Foundation of China(Molecular design,catalysis and synthesis methods of novel fentanyl analogs active compounds)No.20872095
文摘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.
文摘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.
文摘The present study was designed to investigate the effects of intravenously administered agonists and antagonists at μ(DAMGO, naloxone,)δ1 (DPDPE,BNTX)andδ2(DELT, NTB)opioid receptors on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla.Extracellular single unit recording were made from 70 nociceptive neurons(28 NS,42 WDR) in the superficial dorsal horn and 37 nociceptive neurons(4 NS,33 WDR)in the deeper dorsal horn.All these neurons had an ipsilateral orofacial mechanoreceptive field and majority of these neurons had no spontaneous activity. The latencies for the C fiber evoked responses ranged from 34~105 msec whereas for Aδfiber-evoked responses it ranged from 3~22msec. A clear separation was observed between early and late responses of evoked by Cand Aδ-fiber.Application of DPDPE,DELT and DAMGO produced inhibitory effects on the Aδ-and C-fiber evoked responses of nociceptive neurons in the superficial and thedeeper dorsal horn.By comparison,the inhibition was more pronounced on the C-fiber evoked response than on the Aδ-fiber evoked response,and DAMGO produced a stronger inhibitory action than both DELT and DPDPE. Additionally,DPDPE produced facilitation, or inhibition followed by facilitation on the Aδ-and C-response and the effect had longer latency and longer time course.DPDPE also induced completely oppsite effects on the Aδ-and C-fiber evoked responses.Although the facilitation was observed,the effect was not dose-dependent. Application of BNTX (0.4~1mg/kg),a δ1 receptor antagonist,produced antagonism of DPDPE in 88%(7/8) neurons. Application of the doses (0.7~1mg/kg) of BTB,δ2-receptor antagonist,resulted in antagonism of both DELT and DPDPE. The inhibition of DELT on Aδ-response was antagonized by doses (0.3~1mg/kg)of NTB in 100% (14/14)neurons while the antagonism on C-response was in 79%(11/14) neurons.The effect produced by DPDPE was antagonized by the doses (0.7~1mg/kg) of NTB in 100%(4/4) neurons. However,a smaller dose of NTB(0.3mg/kg)which and antagonize the effect of DELT,did not antagonize the effect of DPEPE in 100%(4/4) neurons. The inhibitory action of DAMGO on Aδ-and C-fiber evoked responses was completely antagonized by naloxone(0. 2mg/kg) in 100% (6/6) neurons. These results suggest that:①μ-and δ-opioid receptors play an important role in modulating Aδ-and Cfiber evoked responses of nociceptive neurons in the superficial and the deeper dorsal horn of the rat medulla; ② The inhibitory action produced by DPDPE, DELT and DAMGO was more pronounced on the C-fiber evoked excitation and indicates that the agonists produce more predominant inhibition on the responses of dorsal horn neurons to noxious stimuli; ③ activation of either δ1-orδ2-opioid receptors produces inhibitory actions on Aδ- and C-response of nociceptive neurons in the superficial and the deeper dorsal horn of the medullal;DPDPE and DELT act at different δ-opioid receptor subtypes in the rat rnedulla; ⑤i.v.-administered NTB can distinguish δ-opioid receptor subtypes in a limited dose range.When administered i. v., 0. 3mg/kg of NTB is selective for δ2-opioid receptor.
文摘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.
基金Supported by Council of Scientific and Industrial Research
文摘Protein to protein interactions leading to homo/heteromerization of receptor is well documented in literature. These interactions leading to dimeric/oligomers formation of receptors are known to modulate their function, particularly in case of G-protein coupled receptors. The opioid receptor heteromers having changed pharmacological properties than the constituent protomers provides preferences for novel drug targets that could lead to potential analgesicactivity devoid of tolerance and physical dependence. Heterodimerization of opioid receptors appears to generate novel binding properties with improved specificity and lack of side effects. Further the molecules which can interact simultaneously to both the protomers of the heteromer, or to both the binding sites(orthosteric and allosteric) of a receptor protein could be potential therapeutic molecules. This review highlights the recent advancements in exploring the plausible role of heteromerization of opioid receptors in induction of tolerance free antinociception.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology,China(2016YFC0105501,2019YFD1712000).
文摘Spinal cord stimulation(SCS)-induced analgesia was characterized,and its underlying mechanisms were examined in a spared nerve injury model of neuropathic pain in rats.The analgesic effect of SCS with moderate mechanical hypersensitivity was increased with increasing stimulation intensity between the 20%and 80%motor thresholds.Various frequencies(2,15,50,100,10000 Hz,and 2/100 Hz dense-dispersed)of SCS were similarly effective.SCS-induced analgesia was maintained without tolerance within 24 h of continuous stimulation.SCS at 2 Hz significantly increased methionine enkephalin content in the cerebrospinal fluid.The analgesic effect of 2 Hz was abolished byμorκopioid receptor antagonist.The effect of 100 Hz was prevented by aκantagonist,and that of 10 kHz was blocked by any of theμ,δ,orκreceptor antagonists,suggesting that the analgesic effect of SCS at different frequencies is mediated by different endorphins and opioid receptors.