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

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.
Analgesics, Opioid ; pharmacology ; Humans ; Hypoxia ; metabolism ; Neurons ; metabolism ; Neuroprotective Agents ; pharmacology ; Receptors, Opioid, delta ; metabolism ; Signal Transduction

AIMTo explore the types of receptors distributed in MHb and LHb.

METHODSRecording the currents of potassium channels in Hb neurons isolated from the rats 10-15 days after birth. To distinguish the types of receptors distributed in MHb and LHb by using the agonists of mu receptor DAMGO, and sigma receptor DPDPE.

RESULTSTwo types of current of K+ channels were recorded, the transient rectifier and delayed rectifier potassium channels. DAMGO or DPDPE increased the intensity of current of K+ channels.

CONCLUSIONIn MHb there was a higher density of sigma receptor, and in LHb a higher density of mu receptor distributed.

Animals ; Animals, Newborn ; Habenula ; metabolism ; Neural Pathways ; Neurons ; metabolism ; Potassium Channels ; metabolism ; Rats ; Receptors, Opioid ; metabolism

OBJECTIVETo explore the role of µ-opioid receptors (MOR) in the central nucleus of the amygdala (CeA) in modulating sucrose solution intake in rats.

METHODSSprague-Dawley rats received intra-CeA injection of MOR agonist DAMGO or saline, and then underwent two bottle choice test between sucrose solution and distilled water. After intake of sucrose solution or distilled water, activated neurons in the CeA were labeled and identified with MOR/Fos-double labeling immunohistochemistry.

RESULTSCompared with saline injection, intra-CeA injection of DAMGO significantly increased sucrose solution intake in rats over a 3-h period. Sucrose solution intake induced significantly more c-Fos and MOR/Fos double-labeled neurons in the CeA than distilled water intake.

CONCLUSIONSThe CeA participates in modulation of sucrose intake in rats, and MOR may partly mediate this mechanism.

Amygdala ; metabolism ; Animals ; Male ; Neurons ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid, mu ; metabolism ; Sucrose ; metabolism

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

OBJECTIVE: To investigate whether endogenous nociceptin/orphanin FQ (N/OFQ) can inhibit arrhythmia and expression of β₁-adrenergic receptor (β₁-AR) on the surface of myocardial cell membrane in acute myocardial ischemia rats by Raf kinase inhibitory protein (RKIP). METHODS: (1) Experiment one: according to random number table method, 30 adult male Sprague-Dawley (SD) rats with only 6 weeks of age were divided into Sham group (open the chest but do not ligate the coronary artery), myocardial ischemia model group (coronary ligation of left anterior descending branch), and endogenous N/OFQ antagonists UFP-101 pretreatment group (UFP-101 group, preoperative 10 minutes after tail vein injection of 1 mL/kg UFP-101), with 10 rats in each group. Arrhythmia was recorded within 15 minutes after operation. The expression of phosphorylated RKIP (p-RKIP) was detected by Western Blot. (2) Experiment two: according to the random number table method, 30 4-week-old male SD rats were divided into UFP-101 control group, RKIP over expression group and RKIP antagonism group, with 10 rats in each group. The UFP-101 control group was intraperiton eally injected with corn oil every day, while the other two groups were injected with up adjuster of RKIP (Didymin). The rats in the three groups were all ligated after 4 weeks of feeding, and UFP-101 was injected through the tail vein 10 minutes before the operation. The RKIP antagonist group received intraperitoneal injection of the RKIP-specific antagonist locostatin 2 hours before surgery. Arrhythmia results were recorded within 15 minutes after operation. Western Blot was used to detect the expression of p-RKIP in myocardial tissue and expression of β₁-AR on the surface of myocardial cell membrane 15 minutes after surgery. RESULTS: (1) Experiment one: compared with Sham group, ventricular ectopic beat (VEB), ventricular tachycardia (VT) and ventricular fibrillation (VF) increased significantly in the model group and UFP-101 group, and arrhythmia score increased significantly. In addition, compared with the Sham group, p-RKIP expression was increased in the model group and decreased in the UFP-101 group. Compared with the model group, preconditioning with UFP-101 significantly reduced the occurrence of arrhythmia [arrhythmia score: 1.5 (0.3, 5.0) vs. 4.0 (2.0, 5.0), P < 0.05], and the expression of p-RKIP in myocardial tissue significantly decreased (p-RKIP/total RKIP: 0.20±0.11 vs. 0.43±0.11, P < 0.05). This indicated that antagonistic N/OFQ could reduce the phosphorylation of RKIP and the occurrence of arrhythmia. (2) Experiment two: compared with the UFP-101 control group, overexpression of RKIP significantly increased the occurrence of arrhythmia events, and the expression of β₁-AR on the surface of the myocardial cell membrane significantly increased. And antagonism RKIP overexpression could make the occurrence of arrhythmia eased [arrhythmia score: 3.0 (2.0, 3.0) vs. 4.0 (2.0, 5.0), P < 0.05], and significantly reduce the expression of myocardial cell membrane surface β₁-AR (β₁-AR/Na⁺-K⁺-ATPase: 0.88±0.09 vs. 1.02±0.08, P < 0.05), while there was no significant difference in total RKIP expression (total RKIP/GAPDH: 5.40±0.21 vs. 5.36±0.19, P > 0.05). This indicated that endogenous N/OFQ affected the expression of plasma β₁-AR on the surface of myocardial cell membrane and ischemic arrhythmia in rats through RKIP. CONCLUSIONS Endogenous N/OFQ can affect the expression of plasma β₁-AR on the membrane surface of ischemic myocardium and arrhythmia in rats via increased expression of RKIP phosphorylation.
Animals ; Arrhythmias, Cardiac ; Male ; Opioid Peptides/metabolism* ; Phosphatidylethanolamine Binding Protein ; Rats ; Rats, Sprague-Dawley ; Receptors, Opioid ; Nociceptin

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

AIMTo 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.

METHODSTarget 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.

RESULTSBoth 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.

CONCLUSIONThe 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.

Animals ; Benzomorphans ; chemical synthesis ; chemistry ; pharmacology ; Brain ; metabolism ; Furans ; chemical synthesis ; chemistry ; pharmacology ; Guinea Pigs ; Molecular Structure ; Narcotic Antagonists ; chemical synthesis ; chemistry ; pharmacology ; Radioligand Assay ; Receptors, Opioid ; metabolism ; Receptors, Opioid, delta ; metabolism ; Receptors, Opioid, kappa ; metabolism ; Receptors, Opioid, mu ; metabolism ; Structure-Activity Relationship

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

No abstract available.
Animal ; Cyclic AMP/metabolism ; Cyclic GMP/metabolism ; Neurotransmitters/physiology ; Pharmacology, Clinical/trends* ; Receptors, Adrenergic/physiology ; Receptors, Drug/physiology* ; Receptors, Opioid/physiology