Participação dos receptores delta e kappa-opioides centrais no controle do apetite por sódio em ratos estimulados a ingerir solução salina hepertônica / Participation of delta receptors and central kappa-opioids in control of the sodium appetite in rats stimulated to saline ingerirsolução hepertônica

Alguns estudos sugerem que as vias opioidérgicas centrais parecem desempenhar um papel regulatório no controle da ingestão de água e sal em mamíferos. As ações dos opioides centrais sobre a regulação do controle hidroeletrolítico são mediadas por vários dos subtipos de receptores opioides. O papel dos receptores delta e kappa-opioides centrais neste processo não está adequadamente elucidado sendo necessário mais estudos que o esclareçam. Objetivo: Este estudo investigou o envolvimento dos receptores delta e kappa-opioides centrais no apetite por sódio em ratos depletados deste íon e em rato ativados centralmente com angiotensina. Material e Métodos: Foram utilizados ratos Wistar (270 ± 20 g), submetidos à cirurgia estereotáxica para implante de cânula guia no ventrículo lateral esquerdo (VL), no órgão subfornical (OSF), no núcleo preóptico mediano (MnPO) e no núcleo basolateral da amígdala (BLA). No protocolo de depleção de sódio os animais foram submetidos à injeção subcutânea de furosemida combinada com dieta hipossódica quatro dias após a cirurgia. Neste modelo de estudo os animais receberam injeção intracerebroventricular (i.c.v.) do antagonista delta-opioide naltrindole no quinto dia pós-cirúrgico, nas doses de 5, 10 e 20 nmol/2 μL e do antagonista kappa-opioide, norbinaltorfimina, injetado no OSF, MnPO e BLA, nas doses de 0,5, 1,0 e 2,0 nmol/0,2 μL...

Central opioid pathways seem to have an important role on the control of water and salt intake in mammals, and brain opioid peptides may influence hydroelectrolyte balance through a myriad of actions mediated by distinct opioid receptors. The specific role of central delta and kappa-opioid receptors (DOR and KOR) in this process is far from being fully understood. In the present work, we investigated the role of those receptors in the control of water and salt intake, in sodium-depleted rats and rats with activation central angiotensinergic. Method: Wistar male rats (250 ± 20 g) were used in the experiment after stereotaxic cannulation of the VL left, SFO, MnPO and BLA. To study the effect of the blockade of central DOR and KOR on water and salt intake in rats were sodium depleted by the concomitant use of s.c. injections of furosemide and were kept in hypossodic diet, five days after surgery. In the sixth day, they received i.c.v. injections of a selective delta-opioid receptor antagonist (naltrindole) at the doses of 5, 10 and 20 nmol/2 μL and injections in the SFO, MnPO and BLA of a selective kappa-opioid receptor antagonist (norbinaltorphimine) at the doses of 0.5, 1.0 and 2.0 nmol/0.2 μL...

Role of DOR-β-arrestin1-Bcl2 signal transduction pathway and intervention effects of oxymatrine in ulcerative colitis / 华中科技大学学报（医学）（英德文版）

This study was aimed to investigate the role of the delta-opioid receptor (DOR)-β-arrestin1-Bcl-2 signal transduction pathway in the pathogenesis of ulcerative colitis (UC) and the intervention effects of oxymatrine on UC. Forty Sprague-Dawley rats were divided into normal group, model group, oxymatrine-treated group and mesalazine-treated group (n=10 each) at random. The rat UC model was established by intra-colonic injection of trinitrobenzene sulfonic acid in the model group and two treatment groups. The rats in oxymatrine-treated group were subjected to intramuscular injection of oxymatrine [63 mg/(kg·day)] for 15 days, and those in mesalazine-treated group given mesalazine solution [0.5 g/(kg·day)] by gastric lavage for the same days. Animals in normal group and model group were administered 3 mL water by gastric lavage for 15 days. On the 16th day, after fasting for 24 h, the rats were sacrificed for the removal of colon tissues. The expression levels of DOR, β-arrestin1 and Bcl-2 were determined in colon tissues by immunohistochemistry and real-time quantitative polymerase chain reaction (RT-PCR), respectively. It was found that the expression levels of DOR, β-arrestin1 and Bcl-2 protein and mRNA were significantly increased in the model group as compared with the other groups (P<0.05). They were conspicuously decreased in both mesalazine-treated and oxymatrine-treated groups in contrast to the model group (P<0.05). No statistically significant difference was noted in these indices between mesalazine- and oxymatrinetreated groups (P>0.05). This study indicated that the DOR-β-arrestin1-Bcl-2 signal transduction pathway may participate in the pathogenesis of UC. Moreover, oxymatrine can attenuate the development of UC by regulating the DOR-β-arrestin1-Bcl-2 signal transduction pathway.

Functional activity of the cannabinoid 1 receptor is not affected by opioid antagonists in the rat brain / 대한마취과학회지

BACKGROUND: WIN55212-2 is a synthetic cannabinoid agonist and selective to cannabinoid 1 (CB1) receptors, which are distributed mainly in the central nervous system. Opioid receptors and CB1 receptors have several similarities in terms of their intracellular signal transduction mechanisms, distributions, and pharmacological action. Several studies have therefore sought to describe the functional interactions between opioids and cannabinoids at the cellular and behavioral levels. The present study investigated agonist-stimulated [35S]GTPgammaS binding by WIN55212-2 in rat brain membranes and determined the antagonism by selective opioid antagonists at the level of receptor-ligand interaction and intracellular signal transduction. METHODS: Sprague-Dawley rats (male, n = 20) were euthanized for the preparation of brain membranes. In agonist-stimulated [35S]GTPgammaS binding by WIN55212-2, the values of EC50 and maximum stimulation (% over basal) were determined in the absence or presence of the micro, kappa and delta opioid receptor antagonists naloxone (20 nM), norbinaltorphimine (3 nM), and naltrindole (3 nM), respectively. Ke values for opioid antagonist inhibition in the absence or presence of each opioid receptor antagonist were calculated using the following equation: [nanomolar antagonist] / (dose ratio of EC50 - 1). RESULTS: In WIN55212-2-stimulated [35S]GTPgammaS binding in the rat brain membranes, the values of EC50 and maximum stimulation (% over basal) were 154 +/- 39.5 nM and 27.6 +/- 5.3% over basal, respectively. Addition of selective opioid antagonists did not produce a significant rightward shift in the WIN55212-2 concentration-response curve, and Ke values were not applicable. CONCLUSIONS: Our results suggest that the functional activity of WIN55212-2-stimulated [35S]GTPgammaS binding was not affected by opioid antagonists in the rat brain membranes. Although the exact mechanism remains unclear, our results may partially elucidate their actions.

DADLE suppresses the proliferation of human liver cancer HepG2 cells by activation of PKC pathway and elevates the sensitivity to cis-diammine dichloridoplatium / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect of DADLE, a δ-opioid receptor agonist, on the proliferation of human liver cancer HepG2 cells and explore the mechanism involving PKC pathway.</p><p><b>METHODS</b>HepG2 cells were treated with DADLE at different doses (0.01, 0.1, 1.0 and 10 µmol/L). Cell viability was determined using methyl thiazolyl terazolium (MTT) assay. The expression of PKC mRNA and p-PKC protein were examined by RT-PCR and Western blot assay. After treated separately with DADLE plusing NAL or PMA, the cell cycle of HepG2 cells was analyzed by flow cytometer. MTT was used to detect their proliferation capacity and Western blot was used to examine the p-PKC expression. The growth inhibitory rate of HepG2 cells treated with DADLE and cis-diammine dichloridoplatinum (CDDP) was analyzed.</p><p><b>RESULTS</b>DADLE at different concentrations showed an inhibitory effect on the proliferation of HepG2 cells though inhibiting the expression of PKC mRNA and p-PKC protein. The results of flow cytometry showed that compared with the control group, the percentage of S + G(2)/M cells in DADLE-treated group was lowered by 3.94% (P < 0.01). Meanwhile, after treated with NAL and PMA, the percentage was elevated by 3.22% and 3.63%, respectively (P < 0.01). The MTT and Western blot assays showed that compared with the control group, the values of A570 and p-PKC protein levels in the HepG2 cells of DADLE-treated group were significantly decreased (P < 0.01). After treatment with NAL and PMA, the values of A570 and p-PKC protein levels were elevated significantly (P < 0.01). The growth inhibitory rate of DADLE + CDDP group was 79.9%, significantly lower than 25.2% and 43.2% of the DADLE and CDDP groups, respectively.</p><p><b>CONCLUSIONS</b>Activation of δ-opioid receptor by DADLE inhibits the apoptosis of human liver cancer HepG2 cells. The underlying mechanism may be correlated with PKC pathway. DADLE can enhance the chemosensitivity of HepG2 cells to CDDP.</p>

Pathogenetic mechanism of beta-arrestin1 in experimental colitis of rats and intervention effects of oxymatrine / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the pathogenetic mechanism of beta-arrestin1 in the rat's experimental colitis, whether the delta opioid receptor-beta-arrestin1 -Bcl-2 signal transduction pathway involves the pathological process of experimental colitis in rats, and whether oxymatrine could attenuate colitis through this pathway.</p><p><b>METHODS</b>Twenty-six SD rats were randomly divided into four groups, the normal control group, the model group, the mesalazine treated group and the oxymatrine treated group (8 rats in the last group and 6 each in the others). The colitis model was established with trinitrobenzene sulfonic acid (TNBS), and rats in the latter two groups were treated by oxymatrine (intramuscular injection) and mesalazine (3 mL solution gavaged) for 15 days, respectively, while rats in the former two groups were fed with equal volume of distilled water. Symptoms of diarrhea and bloody stool as well as colonic patho-histologic changes were observed, and changes in expressions of delta opioid receptor, beta-arrestin1 and Bcl-2 in rat's colon tissue and spleen T lymphocytes were detected with immuno-histochemistry and Western immune-blotting techniques, respectively.</p><p><b>RESULTS</b>In contrast to the normal control group, expressions of delta opioid receptor, beta-arrestin1 and Bcl-2 were significantly higher in the model group (P < 0.01); compared with the model group, they were significantly lower in the two treated groups (P < 0.01).</p><p><b>CONCLUSIONS</b>Delta opioid receptor-beta-arrestin1 -Bcl-2 signal transduction pathway participates in the pathogenesis of TNBS-induced experimental colitis in rats. Oxymatrine can intervene the signal transduction, which may be one of the mechanisms of oxymatrine in attenuating colitis in rats.</p>

A novel insight into neuroprotection against hypoxic/ischemic stress / 生理学报

The use of opioid analgesics has a long history in clinical settings, although the functions of opioid receptors, especially their role in the brain, are not well understood yet. Recent studies have generated abundant new data on opioid receptor-mediated functions and the underlying mechanisms. The most exciting finding in the past decade is probably the neuroprotection against hypoxic/ischemic stress mediated by delta-opioid receptors (DOR). An up-regulation of DOR expression and the release of endogenous opioids may increase neuronal tolerance to hypoxic/ischemic stress. The DOR signal triggers, depending on stress duration and severity, different mechanisms at multiple levels to preserve neuronal survival, including the stabilization of ionic homeostasis, an increase in pro-survival signaling (e.g., PKC-ERK-Bcl 2) and the enhanced anti-oxidative capacity. Recent data on DOR-mediated neuroprotection provide us a new concept of neuroprotection against neurological disorders and have a potentially significant impact on the prevention and treatment of some serious neurological conditions, such as stroke.

Design, synthesis and antalgic activities of aralkyl-ketone-4-piperidol derivatives / 药学学报

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.

Construction of delta-pIRES2-EGFP plasmid and its expression in HEK293 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct the delta-pIRES2-EGFP plasmid and investigate its expression in HEK293 cells.</p><p><b>METHODS</b>Full length cDNA of rat delta opioid receptor gene amplified from rat brain tissues using reverse transcription and nested PCR was cloned into pMD20 T vector. The delta cDNA was inserted into pIRES2-EGFP plasmid to construct the recombinant eukaryotic plasmid delta-pIRES2-EGFP, which was transfected into HEK293 cells via Lipofectamine2000. The expression of delta was examined under fluorescence microscope.</p><p><b>RESULTS</b>The recombinant delta-pIRES2-EGFP plasmid was successfully constructed, and high expression of delta was detected in HEK293 cells transfected by the plasmid.</p><p><b>CONCLUSION</b>delta-pIRES2-EGFP has been successfully cloned, which shows high expression of delta in HEK293 cells.</p>

Delta-opioid receptor mediates the cardioprotective effect of ischemic postconditioning / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of 8-opioid receptors in the cardioprotection elicited by ischemic postconditioning and the underlying mechanism.</p><p><b>METHODS</b>The 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 activity of lactate dehydrogenase (LDH) in the coronary effluent was measured. In isolated ventricular myocytes hypoxic postconditioning was achieved by 3 cycles of 5 min reoxygenation/5 min hypoxia starting at the beginning of reoxygenation, and cell viability was measured.</p><p><b>RESULTS</b>In 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 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 naltrindole, an antagonist of delta-opioid receptors and calcium-activated potassium channel (KCa) blocker paxilline attenuated the effect of ischemic/hypoxic postconditioning.</p><p><b>CONCLUSION</b>The findings indicate that ischemic postconditioning protects myocardium against ischemia/reperfusion injury via activating delta-opioid receptors and opening KCa.</p>

Effects of delta-opioid receptor stimulation on survival of cultured myocardial cells upon to serum deprivation / 中国应用生理学杂志

<p><b>AIM</b>To study upon to serum deprivation if delta-opioid receptor activation has direct effect on cultured impaired cardiomyocytes survival.</p><p><b>METHODS</b>Myocardial cells of neonatal rats were cultured in vitro. The cell viability was determined with crystal violet staining uptake. The percentage of S + G2 + M in cell cycle was determined by flow cytometry. Apoptosis rates were determined by flow cytometry (FCM). The expression of Caspase-3 were investigated by Western blotting.</p><p><b>RESULTS</b>Myocardial cells of neonatal rats were cultured of serum-free in vitro, apoptotic index was significantly increased, the expression of Caspase-3 was significantly increased, free-serum induced apoptosis in cardiac myocytes after 48 h. At concentrations of 10 nmol x L(-1) - 10 micromol x L(-1), a delta opoid receptor agonist [D-Ala2, D-Leu5]-enkephalin DADLE promoted the myocardial cells survival, in a concentration-dependent manner. The optimal response was achieved at 0.1 micromol x L(-1), which increase survival index of cardiac myocyte, percentage of S + G2 + M in cell cycle, decrease apoptotic index of cardiac myocyte, and the expression activate caspase-3. Delta-opioid receptor antagonist naltrindole at 10 micromol x L(-1) inhibited the promoting effects of DADLE, which decrease survival index of cardiac myocyte, and percentage of S + G2 + M in cell cycle, increase apoptotic index of cardiac myocyte and the expression of Caspase-3.</p><p><b>CONCLUSION</b>The protective of delta-opioid receptor activation can promote survival in cultured impaired myocardial cells.</p>

Activation of δ-opioid receptors inhibits L-type Ca(2+) current and transient outward K(+) current in rat ventricular myocytes / 生理学报

In the present study, whole-cell patch-clamp technique was used to observe the effects of SNC162, a selective agonist of δ-opioid receptors, on L-type Ca(2+) current (I(Ca-L)) and transient outward K(+) current (I(to)) in rat ventricular myocytes. The results showed that SNC162 significantly inhibited I(Ca-L) and I(to) in rat ventricular myocytes. The maximal inhibition rate of I(Ca-L) and I(to) reached (46.13±4.12)% and (36.53±10.57)%, respectively. SNC162 at 1×10(-4) mol/L inhibited the current density of I(Ca-L) from (8.98±0.40) pA/pF to (4.84±0.44) pA/pF (P<0.01, n=5) and inhibited that of I(to) from (18.69±2.42) pA/pF to (11.73±1.67) pA/pF (P<0.01, n=5). Furthermore, the effects of naltrindole, a highly selective antagonist of δ-opioid receptors, on I(Ca-L) and I(to) were also observed. The results showed that naltrindole alone had no effects on I(Ca-L) and I(to), while it abolished the inhibitory effects of SNC162 on I(Ca-L) and I(to). In conclusion, SNC162 concentration-dependently inhibited I(Ca-L) and I(to) in rat ventricular myocytes via activation of the δ-opioid receptors, which may be a fundamental mechanism underlying the antiarrhythmic effect of activating δ-opioid receptors.

Effects of intracerebroventricular injection of delta-opioid receptor agonist TAN-67 or antagonist naltrindole on acute cerebral ischemia in rat / 生理学报

This work was performed to determine the role of delta-opioid receptor (DOR) in protection against acute ischemia/reperfusion injury. Transient (1 h) focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). DOR agonist TAN-67 (30 nmol, 60 nmol, 200 nmol), DOR antagonist naltrindole (20 nmol, 50 nmol, 100 nmol) or artificial cerebral spinal fluid (aCSF) was injected respectively into the lateral cerebroventricle of the rat 30 min before the induction of brain ischemia. Neurological deficits were assessed by the five-grade system (Longa's methods). The brain infarct was measured by cresyl violet (CV) staining and infarct volume was analyzed by an image processing and analysis system. The expression of DOR was detected by Western blot. The results showed that 60 nmol TAN-67 significantly reduced the infarct volume (P<0.05), attenuated neurological deficits (P<0.05) and tended to increase the expression of about 60 kDa DOR protein (P>0.05), while 100 nmol naltrindole aggravated ischemic damage and decreased about 60 kDa DOR protein expression (P<0.05). These results suggest that DOR activation protects the brain against acute ischemia/reperfusion injury in rat.

Involvement of delta-and mu-opioid receptors in the delayed cerebral ischemic tolerance induced by repeated electroacupuncture preconditioning in rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Preconditioning with repeated electroacupuncture (EA) could mimic ischemic preconditioning to induce cerebral ischemic tolerance in rats. The present study was designed to investigate whether mu (micro)-, delta (delta)- or kappa (kappa)-opioid receptors are involved in the neuroprotection induced by repeated EA preconditioning.</p><p><b>METHODS</b>The rats were pretreated with naltrindole (NTI), nor-binaltorphimine (nor-BNI) or D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), which is a highly selective delta-, kappa- or micro-opioid receptor antagonist respectively, before each EA preconditioning (30 minutes per day, 5 days). Twenty-four hours after the last EA treatment, the middle cerebral artery occlusion (MCAO) was induced for 120 minutes. The brain infarct volume was determined with 2, 3, 5-triphenyltetrazolium chloride staining at 24 hours after MCAO and compared with that in rats which only received EA preconditioning. In another experiment, the met-enkephalin-like immunoreactivity in rat brain was investigated by immunohistochemistry in both EA preconditioning and control rats.</p><p><b>RESULTS</b>The EA preconditioning reduced brain infarct volume compared with the control rats (P = 0.000). Administration of both NTI and CTOP attenuated the brain infarct volume reduction induced by EA preconditioning, presenting with larger infarct volume than that in the EA preconditioning rats (P < 0.001). But nor-BNI administration did not block the infarct volume reduction induced by EA preconditioning, presenting with smaller infarct volume than the control group rats (P = 0.000). The number of met-enkephalin-like immunoreactivity positive neurons in the EA preconditioning rats was more than that of the control rats (P = 0.000).</p><p><b>CONCLUSION</b>Repeated EA preconditioning stimulates the release of enkephalins, which may bind delta- and micro-opioid receptors to induce the tolerance against focal cerebral ischemia.</p>

Protein kinase C is partly involved in c-fos protein expression of nocuously-activated neurons but may not in concomitant modulatory action through opioid receptors at the spinal level in rats / 生理学报

The present study was aimed to examine if protein kinase C (PKC) activation is necessarily involved in both the c-fos protein expression in the nocuously-activated c-fos protein-like immunoreactive (Fos-LI) neurons and the concomitant opioid receptor-mediated modulation in the dorsal horn circuitry of the spinal cord. Formalin was injected into a hindpaw of rats 5 min after the rats were pretreated with intrathecal (i.t.) administration of chelerythrine (Chel), an inhibitor of PKC, naloxone (Nal), combined administration of these two (Chel + Nal), or vehicle (n=5 in each group),respectively. By using immunocytochemical techniques, the formalin-induced Fos-LI neurons in the lumbar dorsal horn were calculated 1 h after formalin injection. The results showed that: (1) i.t. Chel significantly reduced the number of Fos-LI neurons in the dorsal horn of the spinal cord on the side ipsilateral to the formalin injection, showing a decrease by 60.3% (P<0.001) as compared to that observed in the i.t.vehicle group; (2) i.t. Nal significantly increased the number of Fos-LI neurons in the ipsilateral dorsal horn, with an increase of 46.0% (P<0.01) as compared to that in the i.t.vehicle group, the highest percentage increase being found in the deeper laminae of the dorsal horn; and (3) i.t. Chel + Nal also exhibited a significant decrease in Fos-LI neurons in the ipsilateral dorsal horn as compared to i.t. Nal group, showing a reduction of 53.2%, a value similar to that in the i.t. Chel group. These results suggest that: (1) PKC plays a role in the c-fos protein expression only in nearly one half of the Fos-LI neurons in the dorsal horn; and (2) PKC is possibly not involved in the concomitant modulation on the nociception mediated by micro- (and also partly delta-) opioid receptors in the spinal cord.

Dual regulation by delta opioid receptor agonists on the delayed rectified potassium channels in NG108-15 cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the dual effects by the delta opioid receptor agonists DPDPE on the delayed rectified potassium channels in NG108-15 cells.</p><p><b>METHODS</b>A series of outward currents were evoked in NG108-15 cells by depolarizing voltage from -50 mV to +80 mV at holding potential of -90 mV. These currents were delayed rectified potassium currents. Relatively selected delta opioid receptor agonists DPDPE of higher and lower concentrations were used to modulate the delayed rectified K+ current in NG108-15 cells. Opioid receptor antagonist Naloxone (NAL) and relatively selected delta opioid receptor antagonist Naltrindole (NTI) were used in the present experiments for the characterization of the actions of opioid receptors.</p><p><b>RESULTS</b>The relatively higher concentrations of delta opioid receptor agonist DPDPE (> or = 10(-6) mol/L) significantly increased the amplitude of the delayed rectified K+ current. On the contrary, the relatively lower concentrations of DPDPE (< or = 10(-12) mol/L) decreased the amplitude of the delayed rectified K+ current (P < 0.05). Furthermore both the increase and decrease were time-dependent.</p><p><b>CONCLUSIONS</b>delta opioid receptor agonist has dual regulatory effects on the delayed rectified potassium channels in NG108-15 cells.</p>

Synthesis and pharmacology of 8-amino-3-(tetrahydro-2-furanyl)methyl benzomorphan / 药学学报

<p><b>AIM</b>To design and synthesize new chiral 8-(substituted) amino-analogues of 3-[(tetrahydro-2-furanyl)methyl] benzomorphans, to expand knowledge of the structure-activity relationship (SAR) for 8-aminobenzomorphan.</p><p><b>METHODS</b>Target compounds were synthesized from the 8-triflate of the optically active 3-[(tetrahydro-2-furanyl)methyl]-2,6-methano-benzomorphans using Pd-catalyzed aminations. Opioid receptor binding experiments were performed to evaluate their biological activities.</p><p><b>RESULTS</b>Both 8-amino and 8-phenylamino analogues showed lower binding affinity for mu, delta and kappa receptors than corresponding 8-hydroxy-3-[(tetrahydro-2-furanyl)methyl]-2,6-methano-benzomorphan in vitro.</p><p><b>CONCLUSION</b>The relative poor binding affinity of the target compounds did not warrant conducting the in vivo studies to determine if they have the profile(kappa agonist/mu antagonist) that will be potentially useful in the treatment of drug addiction. Further study is in progress.</p>

Assessment of the possible capacity of the synthetic and-opioid receptor agonist DADLE in an experimental model of hypothermic ischemia and reperfusion in isolated rat heart - role of ATP-sensitive potassium channels

Efforts to prevent myocardial ischemia have focused on findings ways to block events associated with irreversible ischemic injury. The discovery of the endogenous cellular protective mechanism known as ischemic preconditioning [ipc] has risen hoping that natural pathways could be activated to help cells to overcome necrosis. Pharmacologic preconditioning has been tried to simulate ipc in cardio protection against ischemia. Aim: the aim of the present study is to assess the possible protective capacities of both [ipc] and the synthetic -opioid receptor agonist dadle in an experimental model of hypothermic ischemia and reperfusion [hir] in isolated rat heart, and to assess whether the effects of both protective measures are similarly mediated via k[atp] channels. Isolated rat hearts were divided into 7 groups: g1: is control normothermic [37°C] perfused hearts. G2 hearts were subjected to 45 min of hypothermic ischemia at 30°C, followed by 25 min of normothermic reperfusion [hir]. G3: ipc for 3 min followed by 5 min normothermic reperfusion then hir as g2. G4: dadle pretreatment [1 mg/kg] 30 min before isolated heart preparation, then the protocol of g2 was done. G5: DADLE pretreatment, then the protocol of G3. G6: glibenclamide [0.3 mg/kg] 60 min pretreatment followed by DADLE after 30 min, then the protocol of g2 was done g7: glibenclamide and dalde pretreatment, followed by protocol of g3. Both ipc and DADLE pretreatment and their combination in groups 3, 4, and 5, respectively, improved the post ischemic recovery in the form of significant increase in heart rate [hr], myocardial contractility, coronary flow [cf], and significant decrease in creative kinas [ck] in coronary effluent with a significant reduction of infarct size [is] to 6.6 +/- 1.5, 3.1 +/- 1.3, and 2.8 +/- 1.2%, respectively, when compared with g1 and g2 with is 17.2 +/- 2.2%. Glibenclamide pretreatment in g6 and g7 abolished this improvement in the post ischemic recovery when compared with groups 3, 4 and 5. The results of the present study indicate that ischemic prerconditioning [ipc] improves post ischemic recovery and reduces myocardial infract size in isolated rat heart. Pretreatment with -opioid receptor agnist DADLE mimicked the cardio protection induced by ipc, indicating an opiod receptor-mediated mechanism. Pharmacologic preconditioning by dasle and ipc has additional effects in improving the post ischemic recovery. Lastly, this cardioprotection induced by both can be abolished by the k[ATP] channel antagonist glibenclamide suggesting an involvement of the k[ATP] channel most probably mitochondrial k[ATP], as an important end-effecter of this potent cardio protective effect

The postburn change in hypothalamic paraventricular beta-endorphin and the roles of delta-receptor in scalded rats / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the postburn change in hypothalamic paraventricular beta-endorphin and the roles of delta-receptor in scalded rats.</p><p><b>METHODS</b>Male Sprague-Dawley (SD) rats were randomly divided into 3 groups, i.e. ICI174864, DPDPE and control groups. The rats were inflicted with 20% TBSA of III degree scalding on the back by boiling (100 degrees ) water. The postburn change in the tissue content of the hypothalamic paraventricular beta-endorphin was determined by radioimmuno assay (RIA). The effects of delta-receptor in scalded shock rats were investigated by observing the change of the rats'survival time and cardiac indices after the micro-injection of delta-receptor agonist DPDPE or antagonist ICI174864 into the hypothalamic paraventricle.</p><p><b>RESULTS</b>(1) The tissue content of the hypothalamic paraventricular beta-endorphin increased significantly (P < 0.01) at 1, 2 and 4 postburn hours (PBHs) in the scalded rats. (2) When compared with that of control group, the ratio of the cardiovascular parameters [mean arterial pressure (MAP), dp/dt(max) and HR] were obviously increased at different time points in rats with pre-injection of ICI174864 whereas the ratio was decreased when DPDPE was used. Nevertheless, the change in the heart rate ratio was not obvious whether ICI174864 or DPDPE was used. (3) The average animal survival time in ICI174864 group was much longer than that in DPDPE group.</p><p><b>CONCLUSION</b>An excessive increase in hypothalamic paraventricular beta-endorphin was one of the factors leading to the aggravation of burn shock and earlier death. delta-receptor located in the tissue might have played important roles in the mediation of the action of hypothalamic paraventricular beta-endorphin. It is beneficial to antagonize the action of delta-receptor for the correction of burn shock and for the prolongation of the of life of animals.</p>

Rat brain membrane-bound delta opioid receptor: loss and reactivation of binding on dialysis and aging at low temperature.

A change in the environment of rat brain membranes by dialysis from phosphate buffered saline (PBS) to 10 mM potassium phosphate (pH 7.2) led to a 35% loss in delta opioid receptor binding, while alteration of membrane structure on freezing at -20 degrees C for 55 days led to 85% loss of receptor binding. The dialysate, 200 mM KCI and NaCl restored receptor binding lost on dialysis. This K+ and Na+ restabilization of the receptor can be through cation-pi bonding, interactions that are suited to the lipid bilayer. In membranes stored at -20 degrees C, the loss of binding is attributed to increased membrane fluidity by phospholipase A2 action on membrane phospholipids, resulting in an increase of free fatty acids. K+ but not Na+ restabilization of these membrane receptors may be due to the ability of K+ to decrease membrane fluidity.

Nociception, antinociceptive potency of morphine in streptozotocin induced diabetic rats.

There are controversial reports on the effect of diabetes on the pain threshold. We used male Wistar rats to see the effect of streptozotocin induced diabetes on the tail flick, vocalisation and vocalisation after discharge responses. These represent the spinal, lower brain stem and hypothalamic responses respectively. The effect of morphine in these parameters was studied for both the control and diabetic group. In diabetic rats, the pain threshold was increased. However, this increase was not significant. Morphine produced significant analgesia after thirty minutes for tail flick and vocalisation responses and after fifteen minutes for after discharge in the control group. The antinociceptive effect of morphine was delayed and reduced for all three pain threshold confirming the antagonistic action of glucose on opiate receptors.