Morphine is a frequently used analgesic that activates the mu-opioid receptor(MOR),which has prominent side effects of tolerance.Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the d...Morphine is a frequently used analgesic that activates the mu-opioid receptor(MOR),which has prominent side effects of tolerance.Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance,currently,there is no effective therapy to treat morphine tolerance.In the current study,we aimed to develop a monoclonal antibody(mAb)precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms.We successfully prepared a mAb targeting MOR,named 3A5C7,by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization,and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation.Treatment of two cell lines,HEK293T and SH-SY5Y,with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2(GRK2)/b-arrestin2-dependent mechanism,as demonstrated by immunofluorescence staining,flow cytometry,Western blotting,coimmunoprecipitation,and small interfering ribonucleic acid(siRNA)-based knockdown.This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR.We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid.Western blot,enzyme-linked immunosorbent assays,and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase,the in vitro biomarker of morphine tolerance,via the GRK2/b-arrestin2 pathway.Furthermore,in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice,and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence.Finally,intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/b-arrestin2 pathway.Collectively,our study provided a therapeutic mAb,3A5C7,targeting MOR to treat morphine tolerance,mediated by enhancing morphine-induced MOR endocytosis.The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.展开更多
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 explore the anti-nociceptive effect of patchouli alcohol(PA), the essential oil isolated from Pogostemon cablin(Blanco) Bent, and determine the mechanism in molecular levels. Methods: The acetic acid-ind...Objective: To explore the anti-nociceptive effect of patchouli alcohol(PA), the essential oil isolated from Pogostemon cablin(Blanco) Bent, and determine the mechanism in molecular levels. Methods: The acetic acid-induced writhing test and formalin-induced plantar injection test in mice were employed to con?rm the effect in vivo. Intracellular calcium ion was imaged to verify PA on mu-opioid receptor(MOR). Cyclooxygenase 2(COX2)and MOR of mouse brain were expressed for determination of PA’s target. Cellular experiments were carried out to find out COX2 and MOR expression induced by PA. Results: PA significantly reduced latency period of visceral pain and writhing induced by acetic acid saline solution(P<0.01) and allodynia after intra-plantar formalin(P<0.01) in mice. PA also up-regulated COX2 mRNA and protein(P<0.05) with a down-regulation of MOR(P<0.05) both in in vivo and in vitro experiments, which devote to the analgesic effect of PA. A decrease in the intracellular calcium level(P<0.05) induced by PA may play an important role in its anti-nociceptive effect.PA showed the characters of enhancing the MOR expression and reducing the intracellular calcium ion similar to opioid effect. Conclusions: Both COX2 and MOR are involved in the mechanism of PA’s anti-nociceptive effect,and the up-regulation of the receptor expression and the inhibition of intracellular calcium are a new perspective to PA’s effect on MOR.展开更多
Although opioids still remain the most powerful pain-killers,the chronic use of opioid analgesics is largely limited by their numerous side-effects,including opioid dependence.However,the mechanism underlying this dep...Although opioids still remain the most powerful pain-killers,the chronic use of opioid analgesics is largely limited by their numerous side-effects,including opioid dependence.However,the mechanism underlying this dependence is largely unknown.In this study,we used the withdrawal symptoms precipitated by naloxone to characterize opioid dependence in mice.We determined the functional role of mu-opioid receptors(MORs)expressed in different subpopulations of neurons in the development of morphine withdrawal.We found that conditional deletion of MORs from glutamatergic neurons expressing vesicular glutamate transporter 2(Vglut2^+)largely eliminated the naloxone-precipitated withdrawal symptoms.In contrast,conditional deletion of MORs expressed in GABAergic neurons had a limited effect on morphine withdrawal.Consistently,mice with MORs deleted from Vglut2^+glutamatergic neurons also showed no morphine-induced locomotor hyperactivity.Furthermore,morphine withdrawal and morphine-induced hyperactivity were not significantly affected by conditional knockout of MORs from dorsal spinal neurons.Taken together,our data indicate that the development of morphine withdrawal is largely mediated by MORs expressed in Vglut2^+glutamatergic neurons.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
Opioids are the most effective painkillers,but their benefit-risk balance often hinder their therapeutic use.WLB-73502 is a dual,bispecific compound that binds sigma-1(S1R)and mu-opioid(MOR)receptors.WLB-73502 is an a...Opioids are the most effective painkillers,but their benefit-risk balance often hinder their therapeutic use.WLB-73502 is a dual,bispecific compound that binds sigma-1(S1R)and mu-opioid(MOR)receptors.WLB-73502 is an antagonist at the S1R.It behaved as a partial MOR agonist at the G-protein pathway and produced no/unsignificantβ-arrestin-2 recruitment,thus demonstrating low intrinsic efficacy on MOR at both signalling pathways.Despite its partial MOR agonism,WLB-73502exerted full antinociceptive efficacy,with potency superior to morphine and similar to oxycodone against nociceptive,inflammatory and osteoarthritis pain,and superior to both morphine and oxycodone against neuropathic pain.WLB-73502 crosses the blood-brain barrier and binds brain S1R and MOR to an extent consistent with its antinociceptive effect.Contrary to morphine and oxycodone,tolerance to its antinociceptive effect did not develop after repeated 4-week administration.Also,contrary to opioid comparators,WLB-73502 did not inhibit gastrointestinal transit or respiratory function in rats at doses inducing full efficacy,and it was devoid of proemetic effect(retching and vomiting)in ferrets at potentially effective doses.WLB-73502 benefits from its bivalent S1R antagonist and partial MOR agonist nature to provide an improved antinociceptive and safety profile respect to strong opioid therapy.展开更多
基金supported by the National Basic Research Program of China(Grant No.:2015CB553701)the National Science and Technology Major Project,China(Grant No.:2019ZX09732001).
文摘Morphine is a frequently used analgesic that activates the mu-opioid receptor(MOR),which has prominent side effects of tolerance.Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance,currently,there is no effective therapy to treat morphine tolerance.In the current study,we aimed to develop a monoclonal antibody(mAb)precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms.We successfully prepared a mAb targeting MOR,named 3A5C7,by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization,and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation.Treatment of two cell lines,HEK293T and SH-SY5Y,with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2(GRK2)/b-arrestin2-dependent mechanism,as demonstrated by immunofluorescence staining,flow cytometry,Western blotting,coimmunoprecipitation,and small interfering ribonucleic acid(siRNA)-based knockdown.This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR.We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid.Western blot,enzyme-linked immunosorbent assays,and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase,the in vitro biomarker of morphine tolerance,via the GRK2/b-arrestin2 pathway.Furthermore,in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice,and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence.Finally,intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/b-arrestin2 pathway.Collectively,our study provided a therapeutic mAb,3A5C7,targeting MOR to treat morphine tolerance,mediated by enhancing morphine-induced MOR endocytosis.The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.
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 the National Natural Science Foundation of China(No.81374006 and No.81073092)the Special Foundation for New Drug Innovation of Tsinghua University(No.20142000077),China
文摘Objective: To explore the anti-nociceptive effect of patchouli alcohol(PA), the essential oil isolated from Pogostemon cablin(Blanco) Bent, and determine the mechanism in molecular levels. Methods: The acetic acid-induced writhing test and formalin-induced plantar injection test in mice were employed to con?rm the effect in vivo. Intracellular calcium ion was imaged to verify PA on mu-opioid receptor(MOR). Cyclooxygenase 2(COX2)and MOR of mouse brain were expressed for determination of PA’s target. Cellular experiments were carried out to find out COX2 and MOR expression induced by PA. Results: PA significantly reduced latency period of visceral pain and writhing induced by acetic acid saline solution(P<0.01) and allodynia after intra-plantar formalin(P<0.01) in mice. PA also up-regulated COX2 mRNA and protein(P<0.05) with a down-regulation of MOR(P<0.05) both in in vivo and in vitro experiments, which devote to the analgesic effect of PA. A decrease in the intracellular calcium level(P<0.05) induced by PA may play an important role in its anti-nociceptive effect.PA showed the characters of enhancing the MOR expression and reducing the intracellular calcium ion similar to opioid effect. Conclusions: Both COX2 and MOR are involved in the mechanism of PA’s anti-nociceptive effect,and the up-regulation of the receptor expression and the inhibition of intracellular calcium are a new perspective to PA’s effect on MOR.
基金We thank Yan-Jing Zhu for technical support.This work was supported by the National Natural Science Foundation of China(31825013 and 61890952)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB32010200).
文摘Although opioids still remain the most powerful pain-killers,the chronic use of opioid analgesics is largely limited by their numerous side-effects,including opioid dependence.However,the mechanism underlying this dependence is largely unknown.In this study,we used the withdrawal symptoms precipitated by naloxone to characterize opioid dependence in mice.We determined the functional role of mu-opioid receptors(MORs)expressed in different subpopulations of neurons in the development of morphine withdrawal.We found that conditional deletion of MORs from glutamatergic neurons expressing vesicular glutamate transporter 2(Vglut2^+)largely eliminated the naloxone-precipitated withdrawal symptoms.In contrast,conditional deletion of MORs expressed in GABAergic neurons had a limited effect on morphine withdrawal.Consistently,mice with MORs deleted from Vglut2^+glutamatergic neurons also showed no morphine-induced locomotor hyperactivity.Furthermore,morphine withdrawal and morphine-induced hyperactivity were not significantly affected by conditional knockout of MORs from dorsal spinal neurons.Taken together,our data indicate that the development of morphine withdrawal is largely mediated by MORs expressed in Vglut2^+glutamatergic neurons.
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 the Centre for the Development of Industrial Technology(Centro para el Desarrollo Tecnológico IndustrialCDTI),references IDI-20130943 and IDI20150915(Spain)。
文摘Opioids are the most effective painkillers,but their benefit-risk balance often hinder their therapeutic use.WLB-73502 is a dual,bispecific compound that binds sigma-1(S1R)and mu-opioid(MOR)receptors.WLB-73502 is an antagonist at the S1R.It behaved as a partial MOR agonist at the G-protein pathway and produced no/unsignificantβ-arrestin-2 recruitment,thus demonstrating low intrinsic efficacy on MOR at both signalling pathways.Despite its partial MOR agonism,WLB-73502exerted full antinociceptive efficacy,with potency superior to morphine and similar to oxycodone against nociceptive,inflammatory and osteoarthritis pain,and superior to both morphine and oxycodone against neuropathic pain.WLB-73502 crosses the blood-brain barrier and binds brain S1R and MOR to an extent consistent with its antinociceptive effect.Contrary to morphine and oxycodone,tolerance to its antinociceptive effect did not develop after repeated 4-week administration.Also,contrary to opioid comparators,WLB-73502 did not inhibit gastrointestinal transit or respiratory function in rats at doses inducing full efficacy,and it was devoid of proemetic effect(retching and vomiting)in ferrets at potentially effective doses.WLB-73502 benefits from its bivalent S1R antagonist and partial MOR agonist nature to provide an improved antinociceptive and safety profile respect to strong opioid therapy.
文摘目的:观察犬急性膝关节炎炎症期滑膜组织μ-阿片受体(mu-opioid receptors,MOR)表达的变化,探讨急性炎症外周局部应用阿片类药物镇痛的可行性。方法:17只Beagle犬随机分为正常对照组(n=8)和急性感染性炎症组(n=9),取各组犬膝关节滑膜组织,采用免疫组织化学及real-ti me PCR方法检测滑膜组织MOR蛋白及mRNA的表达。结果:急性感染性炎症组犬膝关节滑膜组织MOR mRNA相对表达量明显高于正常对照组[(34.40±5.48)%vs(16.54±8.03)%],差异具有统计学意义(P<0.05)。免疫组化染色见炎症滑膜组织MOR染色阳性产物较正常对照颗粒增粗、着色加深、染色带增宽、数量增多;与正常滑膜组织相比,急性感染性炎症组滑膜组织MOR阳性细胞免疫组化指数显著增高[(323175.00±92614.94)vs(175444.10±75149.06)],差异具有统计学意义(P<0.05)。结论:犬膝关节滑膜组织中存在MOR,且在急性感染性炎症早期其表达显著增强。
