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Novel selective κ agonists SLL-039 and SLL-1206 produce potent antinociception with fewer sedation and aversion. Acta Pharmacol Sin 2022; 43:1372-1382. [PMID: 34493813 PMCID: PMC9160296 DOI: 10.1038/s41401-021-00761-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 08/08/2021] [Indexed: 02/07/2023]
Abstract
SLL-039 (N-cyclopropylmethyl-7α-4'-(N'-benzoyl) amino-phenyl-6,14-endoethano-tetrahydronorthebaine) and SLL-1206 (N-cyclopropylmethyl-7α-3'-(p-methoxybenzyl) amino-phenyl-6,14-endoethano-tetrahydronorthebaine) are two 4,5-epoxymorphinan-based high selective κ receptor agonists that we recently discovered. In the present study we characterized their pharmacological properties in comparison with arylacetamide-based typical κ agonist U50,488H. We showed that both SLL-039 and SLL-1206 produced potent and long-lasting antinociceptive actions in three different rodent models of pain via activation of κ opioid receptor. In hot-plate assay, the antinociceptive potency of SLL-039 and SLL-1206 increased about 11-and 17.3-fold compared to U50,488H and morphine, respectively, with ED50 values of 0.4 mg/kg. Following repeated administration, SLL-1206, SLL-039, and U50,488H all developed analgesic tolerance tested in hot-plate assay. U50,488H and SLL-039 produced antipruritic effects in a dose-dependent manner, whereas SLL-1206 displayed some antipruritic effects only at very low doses. In addition, SLL-1206 was capable of decreasing morphine-induced physical dependence. More importantly, SLL-039 and SLL-1206 at effective analgesic doses did not cause sedation and conditioned place aversion (CPA), whereas U50,488H did. In comparison with SLL-039, SLL-1206 caused similar antinociceptive responses, but fewer sedation and CPA. In conclusion, our results suggest that SLL-039 and SLL-1206 have potential to be developed as novel analgesic agents, and 4,5-expoxymorphinan scaffold is an attractive structure for the development of selective κ agonists with fewer side effects.
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Piltonen M, Krokhotin A, Parisien M, Bérubé P, Djambazian H, Sladek R, Dokholyan NV, Shabalina SA, Diatchenko L. Alternative Splicing of Opioid Receptor Genes Shows a Conserved Pattern for 6TM Receptor Variants. Cell Mol Neurobiol 2021; 41:1039-1055. [PMID: 33010019 PMCID: PMC8159799 DOI: 10.1007/s10571-020-00971-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 09/23/2020] [Indexed: 11/18/2022]
Abstract
The opioid receptor (OPR) family comprises the mu-, delta-, and kappa-opioid, and nociceptin receptors that belong to the superfamily of 7-transmembrane spanning G protein-coupled receptors (GPCRs). The mu-opioid receptor is the main target for clinically used opioid analgesics, and its biology has been extensively studied. The N-terminally truncated 6TM receptors isoform produced through alternative splicing of the OPRM1 gene displays unique signaling and analgesic properties, but it is unclear if other OPRs have the same ability. In this study, we have built a comprehensive map of alternative splicing events that produce 6TM receptor variants in all the OPRs and demonstrated their evolutionary conservation. We then obtained evidence for their translation through ribosomal footprint analysis. We discovered that N-terminally truncated 6TM GPCRs are rare in the human genome and OPRs are overrepresented in this group. Finally, we also observed a significant enrichment of 6TM GPCR genes among genes associated with pain, psychiatric disorders, and addiction. Understanding the biology of 6TM receptors and leveraging this knowledge for drug development should pave the way for novel therapies.
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Affiliation(s)
- Marjo Piltonen
- School of Dentistry, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
- Department of Anesthesia, School of Medicine, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
| | - Andrey Krokhotin
- Departments of Pathology, Genetics and Developmental Biology, Stanford Medical School, Howard Hughes Medical Institute, Palo Alto, CA, 94305, USA
| | - Marc Parisien
- School of Dentistry, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
- Department of Anesthesia, School of Medicine, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada
| | - Pierre Bérubé
- Departments of Human Genetics and Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, H3A 0G1, Canada
| | - Haig Djambazian
- Departments of Human Genetics and Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, H3A 0G1, Canada
- McGill University and Génome Québec Innovation Centre, Montreal, Quebec, H3A 0G1, Canada
| | - Rob Sladek
- Departments of Human Genetics and Medicine, Faculty of Medicine, McGill University, Montreal, Quebec, H3A 0G1, Canada
- McGill University and Génome Québec Innovation Centre, Montreal, Quebec, H3A 0G1, Canada
| | - Nikolay V Dokholyan
- Departments of Pharmacology, and Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, 17033-0850, USA
- Departments of Chemistry, and Biomedical Engineering, Penn State, University Park, PA, 16802, USA
| | - Svetlana A Shabalina
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Building 38A, Room S604, 8600 Rockville Pike MSC 3830, Bethesda, MD, 20894-6075, USA.
| | - Luda Diatchenko
- School of Dentistry, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada.
- Department of Anesthesia, School of Medicine, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada.
- Alan Edwards Centre for Research on Pain, McGill University, Genome Building, Room 2201, 740 Dr. Penfield Avenue, Montreal, Quebec, H3A 0G1, Canada.
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3
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Sneddon LU. Comparative Physiology of Nociception and Pain. Physiology (Bethesda) 2018; 33:63-73. [DOI: 10.1152/physiol.00022.2017] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 11/22/2022] Open
Abstract
The study of diverse animal groups allows us to discern the evolution of the neurobiology of nociception. Nociception functions as an important alarm system alerting the individual to potential and actual tissue damage. All animals possess nociceptors, and, in some animal groups, it has been demonstrated that there are consistent physiological mechanisms underpinning the nociceptive system. This review considers the comparative biology of nociception and pain from an evolutionary perspective.
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Affiliation(s)
- Lynne U. Sneddon
- University of Liverpool, Institute of Integrative Biology, The BioScience Building, Liverpool, United Kingdom
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Vardy E, Sassano MF, Rennekamp AJ, Kroeze WK, Mosier PD, Westkaemper RB, Stevens CW, Katritch V, Stevens RC, Peterson RT, Roth BL. Single Amino Acid Variation Underlies Species-Specific Sensitivity to Amphibian Skin-Derived Opioid-like Peptides. ACTA ACUST UNITED AC 2016; 22:764-75. [PMID: 26091169 DOI: 10.1016/j.chembiol.2015.05.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 04/14/2015] [Accepted: 05/01/2015] [Indexed: 01/08/2023]
Abstract
It has been suggested that the evolution of vertebrate opioid receptors (ORs) follow a vector of increased functionality. Here, we test this idea by comparing human and frog ORs. Interestingly, some of the most potent opioid peptides known have been isolated from amphibian skin secretions. Here we show that such peptides (dermorphin and deltorphin) are highly potent in the human receptors and inactive in frog ORs. The molecular basis for the insensitivity of the frog ORs to these peptides was studied using chimeras and molecular modeling. The insensitivity of the delta OR (DOR) to deltorphin was due to variation of a single amino acid, Trp7.35, which is a leucine in mammalian DORs. Notably, Trp7.35 is completely conserved in all known DOR sequences from lamprey, fish, and amphibians. The deltorphin-insensitive phenotype was verified in fish. Our results provide a molecular explanation for the species selectivity of skin-derived opioid peptides.
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Affiliation(s)
- Eyal Vardy
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Maria F Sassano
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Andrew J Rennekamp
- Cardiovascular Research Center and Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Wesley K Kroeze
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA
| | - Philip D Mosier
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, VA 23298, USA
| | - Richard B Westkaemper
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, VA 23298, USA
| | - Craig W Stevens
- Department of Pharmacology & Physiology, Oklahoma State University Center for Health Sciences, 1111 West 17(th) Street, Tulsa, OK 74107, USA
| | - Vsevolod Katritch
- Department of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
| | - Raymond C Stevens
- Department of Biological Sciences and Chemistry, Bridge Institute, University of Southern California, Los Angeles, CA 90089, USA
| | - Randall T Peterson
- Cardiovascular Research Center and Division of Cardiology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, 149 13(th) Street, Charlestown, MA 02129, USA; Broad Institute, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Bryan L Roth
- Department of Pharmacology, UNC Chapel Hill Medical School, 4072 Genetic Medicine Building, 120 Mason Farm Road, Chapel Hill, NC 27514, USA.
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Stevens CW. Bioinformatics and evolution of vertebrate nociceptin and opioid receptors. VITAMINS AND HORMONES 2015; 97:57-94. [PMID: 25677768 DOI: 10.1016/bs.vh.2014.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
G protein-coupled receptors (GPCRs) are ancestrally related membrane proteins on cells that mediate the pharmacological effect of most drugs and neurotransmitters. GPCRs are the largest group of membrane receptor proteins encoded in the human genome. One of the most famous types of GPCRs is the opioid receptors. Opioid family receptors consist of four closely related proteins expressed in all vertebrate brains and spinal cords examined to date. The three classical types of opioid receptors shown unequivocally to mediate analgesia in animal models and in humans are the mu- (MOR), delta- (DOR), and kappa-(KOR) opioid receptor proteins. The fourth and most recent member of the opioid receptor family discovered is the nociceptin or orphanin FQ receptor (ORL). The role of ORL and its ligands in producing analgesia is not as clear, with both analgesic and hyperalgesic effects reported. All four opioid family receptor genes were cloned from expressed mRNA in a number of vertebrate species, and there are enough sequences presently available to carry out bioinformatic analysis. This chapter presents the results of a comparative analysis of vertebrate opioid receptors using pharmacological studies, bioinformatics, and the latest data from human whole-genome studies. Results confirm our initial hypotheses that the four opioid receptor genes most likely arose by whole-genome duplication, that there is an evolutionary vector of opioid receptor type divergence in sequence and function, and that the hMOR gene shows evidence of positive selection or adaptive evolution in Homo sapiens.
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Affiliation(s)
- Craig W Stevens
- Department of Pharmacology and Physiology, Oklahoma State University Center for Health Sciences, Tulsa, Oklahoma, USA.
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7
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Rigon F, Horst A, Kucharski LC, Silva RSM, Faccioni-Heuser MC, Partata WA. Effects of sciatic nerve transection on glucose uptake in the presence and absence of lactate in the frog dorsal root ganglia and spinal cord. BRAZ J BIOL 2014; 74:S191-8. [DOI: 10.1590/1519-6984.26012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 06/13/2013] [Indexed: 01/09/2023] Open
Abstract
Frogs have been used as an alternative model to study pain mechanisms because the simplicity of their nervous tissue and the phylogenetic aspect of this question. One of these models is the sciatic nerve transection (SNT), which mimics the clinical symptoms of “phantom limb”, a condition that arises in humans after amputation or transverse spinal lesions. In mammals, the SNT increases glucose metabolism in the central nervous system, and the lactate generated appears to serve as an energy source for nerve cells. An answerable question is whether there is elevated glucose uptake in the dorsal root ganglia (DRG) after peripheral axotomy. As glucose is the major energy substrate for frog nervous tissue, and these animals accumulate lactic acid under some conditions, bullfrogs Lithobates catesbeianus were used to demonstrate the effect of SNT on DRG and spinal cord 1-[14C] 2-deoxy-D-glucose (14C-2-DG) uptake in the presence and absence of lactate. We also investigated the effect of this condition on the formation of 14CO2 from 14C-glucose and 14C-L-lactate, and plasmatic glucose and lactate levels. The 3-O-[14C] methyl-D-glucose (14C-3-OMG) uptake was used to demonstrate the steady-state tissue/medium glucose distribution ratio under these conditions. Three days after SNT, 14C-2-DG uptake increased, but 14C-3-OMG uptake remained steady. The increase in 14C-2-DG uptake was lower when lactate was added to the incubation medium. No change was found in glucose and lactate oxidation after SNT, but lactate and glucose levels in the blood were reduced. Thus, our results showed that SNT increased the glucose metabolism in the frog DRG and spinal cord. The effect of lactate on this uptake suggests that glucose is used in glycolytic pathways after SNT.
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Affiliation(s)
| | - A Horst
- Universidade Federal do Rio Grande do Sul – UFRGS, Brazil
| | - LC Kucharski
- Universidade Federal do Rio Grande do Sul – UFRGS, Brazil
| | - RSM Silva
- Universidade Federal do Rio Grande do Sul – UFRGS, Brazil
| | | | - WA Partata
- Universidade Federal do Rio Grande do Sul – UFRGS, Brazil
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8
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Vardy E, Mosier PD, Frankowski KJ, Wu H, Katritch V, Westkaemper RB, Aubé J, Stevens RC, Roth BL. Chemotype-selective modes of action of κ-opioid receptor agonists. J Biol Chem 2013; 288:34470-83. [PMID: 24121503 DOI: 10.1074/jbc.m113.515668] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The crystal structures of opioid receptors provide a novel platform for inquiry into opioid receptor function. The molecular determinants for activation of the κ-opioid receptor (KOR) were studied using a combination of agonist docking, functional assays, and site-directed mutagenesis. Eighteen positions in the putative agonist binding site of KOR were selected and evaluated for their effects on receptor binding and activation by ligands representing four distinct chemotypes: the peptide dynorphin A(1-17), the arylacetamide U-69593, and the non-charged ligands salvinorin A and the octahydroisoquinolinone carboxamide 1xx. Minimally biased docking of the tested ligands into the antagonist-bound KOR structure generated distinct binding modes, which were then evaluated biochemically and pharmacologically. Our analysis identified two types of mutations: those that affect receptor function primarily via ligand binding and those that primarily affect function. The shared and differential mechanisms of agonist binding and activation in KOR are further discussed. Usually, mutations affecting function more than binding were located at the periphery of the binding site and did not interact strongly with the various ligands. Analysis of the crystal structure along with the present results provide fundamental insights into the activation mechanism of the KOR and suggest that "functional" residues, along with water molecules detected in the crystal structure, may be directly involved in transduction of the agonist binding event into structural changes at the conserved rotamer switches, thus leading to receptor activation.
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Affiliation(s)
- Eyal Vardy
- From the Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599
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9
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Rigon F, Rossato D, Auler VB, Dal Bosco L, Faccioni-Heuser MC, Partata WA. Effects of sciatic nerve transection on ultrastructure, NADPH-diaphorase reaction and serotonin-, tyrosine hydroxylase-, c-Fos-, glucose transporter 1- and 3-like immunoreactivities in frog dorsal root ganglion. Braz J Med Biol Res 2013; 46:513-20. [PMID: 23739744 PMCID: PMC3854437 DOI: 10.1590/1414-431x20132853] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 03/18/2013] [Indexed: 11/21/2022] Open
Abstract
Frogs have been used as an alternative model to study pain mechanisms. Since we
did not find any reports on the effects of sciatic nerve transection (SNT) on
the ultrastructure and pattern of metabolic substances in frog dorsal root
ganglion (DRG) cells, in the present study, 18 adult male frogs (Rana
catesbeiana) were divided into three experimental groups: naive
(frogs not subjected to surgical manipulation), sham (frogs in which all
surgical procedures to expose the sciatic nerve were used except transection of
the nerve), and SNT (frogs in which the sciatic nerve was exposed and
transected). After 3 days, the bilateral DRG of the sciatic nerve was collected
and used for transmission electron microscopy. Immunohistochemistry was used to
detect reactivity for glucose transporter (Glut) types 1 and 3, tyrosine
hydroxylase, serotonin and c-Fos, as well as nicotinamide adenine dinucleotide
phosphate diaphorase (NADPH-diaphorase). SNT induced more mitochondria with
vacuolation in neurons, satellite glial cells (SGCs) with more cytoplasmic
extensions emerging from cell bodies, as well as more ribosomes, rough
endoplasmic reticulum, intermediate filaments and mitochondria. c-Fos
immunoreactivity was found in neuronal nuclei. More neurons and SGCs surrounded
by tyrosine hydroxylase-like immunoreactivity were found. No change occurred in
serotonin- and Glut1- and Glut3-like immunoreactivity. NADPH-diaphorase occurred
in more neurons and SGCs. No sign of SGC proliferation was observed. Since the
changes of frog DRG in response to nerve injury are similar to those of mammals,
frogs should be a valid experimental model for the study of the effects of SNT,
a condition that still has many unanswered questions.
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Affiliation(s)
- F Rigon
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
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Fleming GJ, Robertson SA. Assessments of thermal antinociceptive effects of butorphanol and human observer effect on quantitative evaluation of analgesia in green iguanas (Iguana iguana). Am J Vet Res 2012; 73:1507-11. [DOI: 10.2460/ajvr.73.10.1507] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Feng Y, He X, Yang Y, Chao D, Lazarus LH, Xia Y. Current research on opioid receptor function. Curr Drug Targets 2012; 13:230-46. [PMID: 22204322 DOI: 10.2174/138945012799201612] [Citation(s) in RCA: 211] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/09/2011] [Accepted: 08/12/2011] [Indexed: 12/11/2022]
Abstract
The use of opioid analgesics has a long history in clinical settings, although the comprehensive action of opioid receptors is still less understood. Nonetheless, recent studies have generated fresh insights into opioid receptor-mediated functions and their underlying mechanisms. Three major opioid receptors (μ-opioid receptor, MOR; δ-opioid receptor, DOR; and κ-opioid receptor, KOR) have been cloned in many species. Each opioid receptor is functionally sub-classified into several pharmacological subtypes, although, specific gene corresponding each of these receptor subtypes is still unidentified as only a single gene has been isolated for each opioid receptor. In addition to pain modulation and addiction, opioid receptors are widely involved in various physiological and pathophysiological activities, including the regulation of membrane ionic homeostasis, cell proliferation, emotional response, epileptic seizures, immune function, feeding, obesity, respiratory and cardiovascular control as well as some neurodegenerative disorders. In some species, they play an essential role in hibernation. One of the most exciting findings of the past decade is the opioid-receptor, especially DOR, mediated neuroprotection and cardioprotection. The upregulation of DOR expression and DOR activation increase the 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 homeostasis and increased pro-survival signaling (e.g., PKC-ERK-Bcl 2) and antioxidative capacity. In the heart, PKC and KATP channels are involved in the opioid receptor-mediated cardioprotection. The DOR-mediated neuroprotection and cardioprotection have the potential to significantly alter the clinical pharmacology in terms of prevention and treatment of life-threatening conditions like stroke and myocardial infarction. The main purpose of this article is to review the recent work done on opioids and their receptor functions. It shall provide an informative reference for better understanding the opioid system and further elucidation of the opioid receptor function from a physiological and pharmacological point of view.
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Affiliation(s)
- Yuan Feng
- Yale University School of Medicine, New Haven, CT, USA
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12
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Vallarino M, d'Amora M, Dores RM. New insights into the neuroanatomical distribution and phylogeny of opioids and POMC-derived peptides in fish. Gen Comp Endocrinol 2012; 177:338-47. [PMID: 22575795 DOI: 10.1016/j.ygcen.2012.04.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 04/09/2012] [Accepted: 04/13/2012] [Indexed: 01/13/2023]
Abstract
This review re-evaluates the use of immunological probes to map enkephalinergic, dynorphinergic, and endorphinergic circuits in the CNS of lobe-finned fishes, ray-finned fishes, and cartilaginous fishes in light of the characterization of proenkephalin, prodynorphin, and POMC sequences from representatives of these groups of fish over the past 20 years. The use of α-MSH specific antisera is a reliable method for detecting POMC immunopositive cell bodies and fibers. Since α-MSH and β-endorphin are co-localized in the same neurons, these studies also reveal the distribution of endorphinergic networks. Met-enkephalin specific antisera can be used to detect enkephalinergic circuits in the CNS of gnathostomes because of the ubiquitous presence of this pentapeptide in the proenkephalin sequences of gnathostomes. However, the use of leu-enkephalin specific antisera to detect enkephalinergic networks is more problematic. While this immunological probe is appropriate for analyzing enkephalinergic networks in mammals and perhaps teleosts, for the lungfishes and cartilaginous fishes this probe is more likely able to detect dynorphinergic circuits. In this regard, there is a need to re-examine dynorphinergic networks in non-mammalian gnathostomes by using species specific antisera directed against dynorphin end-products.
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Abstract
INTRODUCTION Although endomorphins-1 (EM-1; H-Tyr-Pro-Phe-Trp-NH(2)) and -2 (EM-2; H-Tyr-Pro-Phe-Phe-NH(2)) are primarily considered agonists for the μ-opioid receptor (MOR), systematic alterations to specific residues provided antagonists and ligands with mixed μ/δ-opioid properties, suitable for application to health-related topics. While the application of endomorphins as antinociceptive agents and numerous biological endpoints were experimentally delineated in laboratory animals and in vitro, clinical use is currently absent. However, structural alterations provide enhanced stability; formation of MOR antagonists or mixed and dual μ/δ-acting ligands could find considerable therapeutic potential. AREAS COVERED This review attempts to succinctly provide insight on the development and bioactivity of endomorphin analogues during the past decade. Rational design approaches will focus on the engineering of endomorphin agonists, antagonists and mixed ligands for their application as a multi-target ligand. EXPERT OPINION Aside from alleviating pain, EM analogues open new horizons in the treatment of medical syndromes involving neural reward mechanisms and extraneural regulation effects on homeostasis. Highly selective MOR antagonists may be promising to reduce inflammation, attenuate addiction to drugs and excess consumption of high-caloric food, ameliorate alcoholism, affect the immune system and combat opioid bowel dysfunction.
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Affiliation(s)
- Lawrence H Lazarus
- National Institute of Environmental Health Sciences, Laboratory of Toxicology and Pharmacology, 111 South TW Alexander Drive, Research Triangle Park, NC 27709, USA.
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14
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A comprehensive study on the putative δ-opioid receptor (sub)types using the highly selective δ-antagonist, Tyr-Tic-(2S,3R)-β-MePhe-Phe-OH. Neurochem Int 2011; 59:192-201. [DOI: 10.1016/j.neuint.2011.04.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 04/19/2011] [Accepted: 04/21/2011] [Indexed: 11/23/2022]
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15
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Bojnik E, Boynik E, Corbani M, Babos F, Magyar A, Borsodi A, Benyhe S. Phylogenetic diversity and functional efficacy of the C-terminally expressed heptapeptide unit in the opioid precursor polypeptide proenkephalin A. Neuroscience 2011; 178:56-67. [DOI: 10.1016/j.neuroscience.2011.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 01/04/2011] [Accepted: 01/05/2011] [Indexed: 01/28/2023]
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Abstract
Preclinical studies of analgesia in amphibians or recommendations for clinical use of analgesics in amphibian species are extremely limited. This article briefly reviews the issues surrounding the use of analgesics in amphibians, starting with common definitions of pain and analgesia when applied to nonhuman animals. Nociceptive and endogenous opioid systems in amphibians are reviewed, and results of preclinical research on opioid and nonopioid analgesics summarized. Recommended opioid and nonopioid analgesics are summarized, and practical recommendations made for their clinical use.
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Affiliation(s)
- Craig W Stevens
- Department of Pharmacology & Physiology, Oklahoma State University-Center for Health Sciences, 1111 West 17th Street, Tulsa, OK 74107, USA.
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Stevens CW, Martin KK, Stahlheber BW. Nociceptin produces antinociception after spinal administration in amphibians. Pharmacol Biochem Behav 2009; 91:436-40. [PMID: 18804120 PMCID: PMC2662521 DOI: 10.1016/j.pbb.2008.08.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/15/2008] [Accepted: 08/25/2008] [Indexed: 11/23/2022]
Abstract
Nociceptin, also known as orphanin FQ, is a opioid-like neuropeptide that mediates its effects at the nociceptin receptor, a member of the G protein-coupled receptor superfamily. In mammals, nociceptin produces analgesia after spinal administration, however the role of nociceptin and nociceptin receptors in the modulation of noxious stimuli in non-mammalian species has not been examined. In an amphibian pain model using the acetic acid test with Rana pipiens, nociceptin and nociceptin1-13 amide produced dose-dependent antinociception (1-100 nmol), blocked by the nociceptin antagonist, [Nphe1]-nociceptin1-13 amide (30 nmol), but not the opioid antagonist, naltrexone (100 nmol/g, s.c.). Conversely, the antinociceptive effects of micro, delta, and kappa opioid receptor agonists were not blocked by the nociceptin antagonist. Nociceptin and nociceptin1-13 amide were the least potent of the opioid agonists tested. These studies demonstrate that spinal nociceptin receptors and not opioid receptors mediate the antinociceptive effect of nociceptin. Considered with previous findings, these behavioral data supports a role for nociceptin inhibition of spinal nociception in amphibians and perhaps all vertebrates.
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Affiliation(s)
- Craig W Stevens
- Department of Pharmacology and Physiology, Oklahoma State University-Center for Health Sciences, College of Osteopathic Medicine, Tulsa, OK 74107-1898, USA.
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Abstract
The proteins that mediate the analgesic and other effects of opioid drugs and endogenous opioid peptides are known as opioid receptors. Opioid receptors consist of a family of four closely-related proteins belonging to the large superfamily of G-protein coupled receptors. The three types of opioid receptors shown unequivocally to mediate analgesia in animal models are the mu (MOR), delta (DOR), and kappa (KOR) opioid receptor proteins. The role of the fourth member of the opioid receptor family, the nociceptin or orphanin FQ receptor (ORL), is not as clear as hyperalgesia, analgesia, and no effect was reported after administration of ORL agonists. There are now cDNA sequences for all four types of opioid receptors that are expressed in the brain of six species from three different classes of vertebrates. This review presents a comparative analysis of vertebrate opioid receptors using bioinformatics and data from recent human genome studies. Results indicate that opioid receptors arose by gene duplication, that there is a vector of opioid receptor divergence, and that MOR shows evidence of rapid evolution.
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Affiliation(s)
- Craig W Stevens
- Department of Pharmacology and Physiology, Oklahoma State University-Center for Health Sciences, Tulsa, OK, USA.
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Brasel CM, Sawyer GW, Stevens CW. A pharmacological comparison of the cloned frog and human mu opioid receptors reveals differences in opioid affinity and function. Eur J Pharmacol 2008; 599:36-43. [PMID: 18930720 PMCID: PMC2600596 DOI: 10.1016/j.ejphar.2008.09.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 10/21/2022]
Abstract
This study presents a direct comparison of the ligand binding and signaling profiles of a mammalian and non-mammalian mu opioid receptor. Opioid ligand binding and agonist potencies were determined for an amphibian (Rana pipiens) mu opioid receptor (rpMOR) and the human mu opioid receptor (hMOR) in transfected, intact Chinese hamster ovary (CHO) cells. Identical conditions were employed such that statistically meaningful differences between the two receptors could be determined. Identifying these differences is an important first step in understanding how evolutionary changes affect ligand binding and signaling in vertebrate opioid receptors. As expected, the rank of opioid ligand affinity for rpMOR and hMOR was consistent with the ligands' previously characterized type-selectivity. However, most of the opioid ligands tested had significant differences in affinity for rpMOR and hMOR. For example, the mu-selective agonist, DAMGO ([d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin), had a 10.9-fold greater affinity (K(i)) for hMOR (K(i)=268 nM) than rpMOR (K(i)=2914 nM). In addition, differences in signaling between these receptors were found by measuring inhibition of cAMP accumulation by morphine or DAMGO. DAMGO was significantly more potent (13.6-fold) in CHO cells expressing hMOR versus those expressing rpMOR. In addition, a significantly greater maximal inhibition was elicited by both opioid agonists in cells expressing hMOR. In summary, this study supports an ongoing effort to better understand how vertebrate evolution has shaped opioid receptor properties and function.
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Affiliation(s)
- Chris M. Brasel
- Dept. of Pharmacology and Physiology, OSU-Center for Health Sciences, Tulsa, OK, USA
| | - Gregory W. Sawyer
- Dept. of Biochemistry and Microbiology, OSU-Center for Health Sciences, Tulsa, OK, USA
| | - Craig W. Stevens
- Dept. of Pharmacology and Physiology, OSU-Center for Health Sciences, Tulsa, OK, USA
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Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
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Abstract
The opioid peptides and receptors have prominent roles in pain transmission and reward mechanisms in mammals. The evolution of the opioid receptors has so far been little studied, with only a few reports on species other than tetrapods. We have investigated species representing a broader range of vertebrates and found that the four opioid receptor types (delta, kappa, mu, and NOP) are present in most of the species. The gene relationships were deduced by using both phylogenetic analyses and chromosomal location relative to 20 neighboring gene families in databases of assembled genomes. The combined results show that the vertebrate opioid receptor gene family arose by quadruplication of a large chromosomal block containing at least 14 other gene families. The quadruplication seems to coincide with, and, therefore, probably resulted from, the two proposed genome duplications in early vertebrate evolution. We conclude that the quartet of opioid receptors was already present at the origin of jawed vertebrates approximately 450 million years ago. A few additional opioid receptor gene duplications have occurred in bony fishes. Interestingly, the ancestral receptor gene duplications coincide with the origin of the four opioid peptide precursor genes. Thus, the complete vertebrate opioid system was already established in the first jawed vertebrates.
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Sladky KK, Kinney ME, Johnson SM. Analgesic efficacy of butorphanol and morphine in bearded dragons and corn snakes. J Am Vet Med Assoc 2008; 233:267-73. [DOI: 10.2460/javma.233.2.267] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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