Humans ; Dynorphins/metabolism* ; Receptors, Opioid, kappa/metabolism* ; Cryoelectron Microscopy

Amygdala ; drug effects ; metabolism ; Animals ; Conditioning (Psychology) ; Morphine ; adverse effects ; Rats ; Receptors, Opioid, kappa ; metabolism

This study investigates whether kappa-opioid receptor and ORL1 receptor may interact to form a heterodimer. In immunofluorescence and co-immunoprecipitation experiments, differentially epitope-tagged receptors, colocalization and heterodimerization of kappa-opioid receptor and ORL1 receptor were used and examined in primary culturing rat neurons, Chinese hamster ovary (CHO) or human embryonic kidney 293 (HEK293) cells. The results show that fluorescence of both kappa-opioid receptor and ORL1 receptor were overlapping in primary culturing hippocampal and cortical neurons. Similarly in co-expressing CHO or HEK293 cells, HA-KOR and Myc-ORL1 were almost exclusively confined to the membranes, revealing extensive colocalization. When Flag-KOR and Myc-ORL1 were co-expressing in CHO cells, heterodimerization was identified to have the ability to co-immunoprecipitate ORL1-receptors with kappa-opioid receptor and vice versa. In the current study, further evidence was provided for the direct interaction of two subtypes of opioid receptors, kappa-opioid receptor and ORL1-receptor, to form the heterodimerization. The finding represents the novel pharmacological mechanism for modulation of opioid receptor function as well as diversity of G protein-coupled receptors.
Animals ; CHO Cells ; Cells, Cultured ; Cerebral Cortex ; cytology ; metabolism ; Cricetinae ; Cricetulus ; Dimerization ; Female ; HEK293 Cells ; Hippocampus ; cytology ; metabolism ; Humans ; Immunoprecipitation ; Male ; Neurons ; cytology ; metabolism ; Rats ; Rats, Wistar ; Receptors, Opioid ; metabolism ; Receptors, Opioid, kappa ; metabolism

OBJECTIVETo determine the effect of activation of lambda-opioid receptor with U50, 488H, a selective kappa-opioid receptor agonist, on the changes in electrical coupling during prolonged ischemia and to explore the possible mechanism.

METHODSThe isolated rat heart was perfused in a Langendorff apparatus. The effect of U50, 488H on electrical coupling parameters including onset of uncoupling, plateau time, slope and fold increase in r(t) was observed in isolated perfused rat heart subjected to global no-flow ischemia. The effect of U50, 488H on connexin 43 (Cx43) expression of ventricular muscle during ischemia was determined by immunohistochemistry.

RESULTSIn the prolonged ischemia model, U50, 488H concentration dependently delayed the onset of uncoupling, increased time to plateau, and decreased the maximal rate of uncoupling during ischemia. The effect of U50, 488H on electrical uncoupling parameters during ischemia was abolished by a selective kappa-opioid receptor antagonist nor-BNI or a PKC inhibitor chelerythrine. The amount of Cx43 immunoreactive signal in ventricular muscle was greatly reduced after ischemia. U50, 488H markedly increased Cx43 expression during ischemia and its effect was also attenuated by nor-BNI or chelerythrine.

CONCLUSIONThese results demonstrated that U50, 488H delayed the onset of uncoupling and plateau time, decreased the maximal rate of uncoupling and increased Cx43 expression of ventricular muscle during ischemia, and these effects of U50, 488H were mediated by kappa-opioid receptor, in which activation of PKC was involved. The effect of U50, 488H on electrical coupling during ischemia was probably correlated with preservation of Cx43 in cardiac muscle.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Animals ; Benzophenanthridines ; pharmacology ; Connexin 43 ; metabolism ; Female ; Heart ; drug effects ; In Vitro Techniques ; Myocardial Ischemia ; metabolism ; physiopathology ; Myocardium ; metabolism ; Naltrexone ; analogs & derivatives ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; metabolism ; Signal Transduction ; drug effects

OBJECTIVETo observe the effects of kappa-opioid receptor stimulation on high glucose induced myocardial hypertrophy of neonatal rats.

METHODSUsing cultured myocardial cells as a model, the protein content was assayed with Lowrys method. The cardiomyocytes volumes were measured by computer photograph analysis system. The level of p-ERK44/42 was determined by Western blot.

RESULTSCompared with the control, U50488H significantly inhibited the protein content and volumes of cultured hypertrophic myocardial cells induced by high glucose. Meanwhile the role of ERK was important.

CONCLUSIONThe stimulation of kappa-opioid can inhibit myocardial hypertrophy induced by high glucose, which is possibly via attenuating p-ERK.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Animals ; Animals, Newborn ; Cardiomegaly ; metabolism ; Cells, Cultured ; Female ; Glucose ; adverse effects ; MAP Kinase Signaling System ; Male ; Myocytes, Cardiac ; drug effects ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; metabolism

AIMTo observe the neuroprotective effect of limb ischemic post-conditioning (LIPC) on local brain ischemia and reperfusion injury in rat, and to investigate whether mitochondrial ATP sensitive potassium channel (mito K(ATP)) and kappa-opioid receptor were involved in the neuroprotection.

METHODSRats were randomly divided into 6 groups that were ischemia/reperfusion group, unilateral hindlimb ischemia group (uLIPC), bilateral hindlimbs ischemia group (bLIPC), bLIPC + antagonist of kappa-opioid receptor nor-binaltorphimine (nor-BNI) group, bLIPC + mito K(ATP) blocker 5-hydroxydecanoate(5-HD) group, bLIPC + extracorporeal circulation of bilateral hindlimbs via femoral arteries (EC) group. Cerebral ischemia was induced by middle cerebral artery occlusion (MCAO), neurological scores, plasma levels of dynorphin and enkephalin, the brain infarct areas were determined after reperfusion.

RESULTSUnilateral LIPC partially improved the neurological score after local brain ischemia and reperfusion injury in rat (P < 0.05), and decreased the infarct area compared with the untreated group undergoing brain ischemia and reperfusion (P < 0.01). Bilateral LIPC significantly improved the neurological score after local brain ischemia and reperfusion injury (P < 0.01), and decreased the infarct area (P < 0.01). The neurological scores of bilateral LIPC group were significant higher than those of unilateral LIPC (P < 0.05). The plasma level of dynorphin was significantly increased (P < 0.01) at 5, 15, 30 min, 1 and 2 h after bilateral LIPC, however, it deceased to the normal level at 12 h after bilateral LIPC. The plasma level of enkephalin showed no obvious change after bilateral LIPC (P > 0.05). nor-BNI (25 nmol/L) and 5-HD (10 mg/kg) abolished the effect of bilateral LIPC (P < 0.01).

CONCLUSIONLIPC protects rat from local brain ischemia and reperfusion injury. Mito K(ATP) may be involved in the neuroprotection, and kappa-opioid receptor may also participate in the protective effect.

Animals ; Brain Ischemia ; physiopathology ; Extremities ; blood supply ; Ischemic Postconditioning ; methods ; Male ; Potassium Channels ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; metabolism ; Reperfusion Injury ; prevention & control

A series of aralkyl-ketone-4-piperidol derivatives were synthesized and tested for their analgesic activities. All of the novel 30 compounds were prepared from 4-piperidone and alpha-halo-aralkyl-ketone through five steps, including Boc protection, nucleophilic addition in presence of CeCl3/NaI catalyst, deprotection, condensation and salification. Their structures were confirmed by 1H NMR and HRMS. Preliminary in vivo pharmacological trials showed that most of the synthesized compounds revealed analgesic effects. Among the tested compounds, 8, 13 and 22 exhibited potent analgesic activities in both mice writhing and mice hot plate model. The three compounds have low affinity for mu, delta, kappa receptors, which is a chance to find a better precursor of non-opioid analgesic for further optimization.
Analgesics, Non-Narcotic ; chemical synthesis ; chemistry ; pharmacology ; Animals ; Mice ; Molecular Structure ; Pain Measurement ; Pain Threshold ; drug effects ; Piperidones ; chemical synthesis ; chemistry ; pharmacology ; Receptors, Opioid, delta ; metabolism ; Receptors, Opioid, kappa ; metabolism ; Receptors, Opioid, mu ; metabolism ; Structure-Activity Relationship

OBJECTIVETo investigate the effect of kappa-Opioid receptors in the cardioprotection elicited by ischemic postconditioning and the underlying mechanism.

METHODSThe isolated perfused hearts of male Sprague-Dawley rats were subjected to 30 min of global ischemia followed by 120 min of reperfusion. formazan content of myocardium was measured spectrophotometrically, and the level of lactate dehydrogenase (LDH) in the coronary effluent was also measured. In isolated ventricular myocytes hypoxia postconditioning was achieved by 3 cycles of 5 min reoxygenation/5 min hypoxia starting at the beginning of reoxygenation, and cell viability was measured.

RESULTIn the Langendorff perfused rat heart model, ischemic postconditioning (6 cycles of 10 s reperfusion/10 s global ischemia starting at the beginning of reperfusion) increased formazan content, reduced LDH release, improved the recovery of the left ventricular developed pressure, maximal rise/fall rate of left ventricular pressure, left ventricular end-diastolic pressure and rate pressure product (left ventricular developed pressure multiplied by heart rate), attenuated the decrease of coronary flow during reperfusion and increased the isolated cell viability. Pretreatment with nor-BNI, an antagonist of kappa-Opioid receptors and mitoK(ATP) blocker 5-HD attenuated the effect of ischemic/hypoxic postconditioning.

CONCLUSIONPostconditioning may protect myocardium against ischemia/reperfusion injury via activating kappa-Opioid receptors and mitoK(KATP).

Animals ; In Vitro Techniques ; Ischemic Preconditioning, Myocardial ; methods ; L-Lactate Dehydrogenase ; metabolism ; Male ; Myocardial Reperfusion Injury ; metabolism ; physiopathology ; prevention & control ; Myocardium ; metabolism ; pathology ; Potassium Channels ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; metabolism ; physiology

OBJECTIVETo determine whether U50488H, a selective agonist of kappa-opioid receptor, could induce biphasic (early and late) cardioprotection against myocardial ischemia/reperfusion injury and to explore the underlying mechanisms.

METHODSIsolated perfused rat hearts were subjected to 30 min of ischemia followed by 120 min reperfusion and the cardiac function was evaluated.

RESULTLeft ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (LVDP) and maximal velocity of contraction and relaxation (+/-dP/dtmax) were improved when U50488H was administered 1 or 24 h before ischemia (P<0.05). Myocardial infarct size, activities of creatine kinase (CK) and lactate dehydrogenase (LDH) in the coronary effluent were lower in the U50488H pretreatment group than those in the control group. Administration of a selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib abolished the late phase of cardioprotection produced by administration of U50488H 24 h before ischemia. Activities of CK and LDH in the coronary effluent were higher in U50488H and celecoxib co-pretreatment group than those in U50488H group. However, administration of celecoxib did not block the early phase of cardioprotection by 1 h treatment of U50488H before ischemia.

CONCLUSIONThe late (but not the early) phase of cardioprotection induced by kappa-opioid receptor agonist might be mediated by COX-2.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Animals ; Cardiotonic Agents ; pharmacology ; Creatine Kinase ; metabolism ; Cyclooxygenase 2 ; physiology ; In Vitro Techniques ; Ischemic Preconditioning, Myocardial ; L-Lactate Dehydrogenase ; metabolism ; Male ; Myocardial Infarction ; enzymology ; pathology ; Myocardial Reperfusion Injury ; prevention & control ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; agonists

AIMTo determine whether activation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical uncoupling during prolonged ischemia and whether these changes in electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation, and to explore the possible mechanism.

METHODS(1) To observe the effect of U50,488H (10(-7), 10(-6), 3 x10(-6) and 10(-5) mol/L), a selective kappa-opioid receptor agonist, or with a selective kappa-opioid receptor antagonist nor-BNI (5 x 10(-6) mol/L), or with a mitochondrial K(ATP) channel inhibitor 5-HD on myocardium during ischemia/reperfusion in isolated perfused rat heart. Parameters of measurements include hemodynamic data, formazan content, heart rate, coronary flow, and lactate dehydrogenase (LDH). (2) To examine the effect of U50,488H of different concentration on electrical coupling parameters (including onset of uncoupling, plateau time, slope, and fold increase in r1) during 70 min myocardial ischemia in isolated perfused rat heart.

RESULTS(1) Pretreatment with U50,488H concentration dependently increased formazan content and reduced LDH release induced by 30 min of ischemia and 120 min of reperfusion. (2) The onset of electrical uncoupling and plateau time during prolonged ischemia was delayed by kappa-opioid receptor activation with U50,488H. (3) Linear regression analysis shown that the increase in formazan content and decrease in LDH release produced by kappa-opioid receptor activation was associated with delayed electrical uncoupling during prolonged ischemia. (4) The effects of U50,488H on formazan content, LDH release and on electrical coupling were abolished by nor-BNI, or 5-HD.

CONCLUSIONThis results demonstrate that the onset of electrical uncoupling during prolonged ischemia is delayed by kappa-opioid receptor activation with a selective kappa-opioid receptor agonist U50,488H, and that delayed electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation with U50,488H. These effects of kappa-opioid receptor activation with U50,488H are mediated by mitochondrial K(ATP) channels.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer ; pharmacology ; Animals ; Antihypertensive Agents ; Heart ; drug effects ; physiopathology ; In Vitro Techniques ; Male ; Myocardial Ischemia ; physiopathology ; Myocardium ; metabolism ; Naltrexone ; analogs & derivatives ; pharmacology ; Potassium Channels ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, kappa ; agonists