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Mei HR, Hu YY, Kapadia S, Ouimet T, Poras H, Dussor G. Efficacy of dual enkephalinase inhibition in a preclinical migraine model is mediated by activation of peripheral delta opioid receptors. Headache 2023; 63:621-633. [PMID: 37183526 PMCID: PMC10646790 DOI: 10.1111/head.14517] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/07/2023] [Accepted: 03/27/2023] [Indexed: 05/16/2023]
Abstract
OBJECTIVE The aim of this study was to evaluate whether elevating levels of enkephalin by inhibiting their degradation can attenuate stress-induced migraine-like behaviors in mice. BACKGROUND Previous studies in animals have suggested the delta opioid receptor (DOR) as a novel migraine target. The primary endogenous ligands for DOR are enkephalins and their levels can be increased by pharmacological inhibition of enkephalinases; however, it is not clear whether enkephalinase inhibition can be efficacious in preclinical migraine models through activation of DOR or whether other opioid receptors might be involved. Further, it is not clear whether opioid receptors in the central nervous system are necessary for these effects. METHODS This study used a model of repetitive restraint stress in mice that induces periorbital hypersensitivity and priming to the nitric oxide donor sodium nitroprusside (SNP; 0.1 mg/kg). Von Frey filaments were used to measure periorbital mechanical thresholds and grimace scores were evaluated by observing mouse facial features. Animals were treated with the dual enkephalinase inhibitor (DENKI) PL37. RESULTS On day two post-stress, PL37 given to mice via either intravenous injection (10 mg/kg) or oral gavage (20 mg/kg) significantly attenuated stress-induced periorbital hypersensitivity and facial grimace responses. Additionally, both intravenous (10 mg/kg) and oral gavage (20 mg/kg) of PL37 prior to SNP (0.1 mg/kg) administration on day 14 post-stress significantly reduced SNP-induced facial hypersensitivity. Injection of the DOR antagonist naltrindole (0.1 mg/kg) but not the mu-opioid receptor antagonist CTAP (1 mg/kg) prior to PL37 treatment blocked the effects. Finally, pretreatment of mice with the peripherally restricted opioid receptor antagonist naloxone methiodide (5 mg/kg) blocked the effects of PL37. CONCLUSIONS These data demonstrate that inhibiting enkephalinases, and thus protecting enkephalins from degradation, attenuates stress-induced migraine-like behavior via activation of peripheral DOR. Peripheral targeting of endogenous opioid signaling may be an effective therapeutic strategy for migraine.
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Affiliation(s)
- Hao-Ruei Mei
- Department of Neuroscience, University of Texas at Dallas, Texas, United States
- School of Behavioral and Brain Science, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, United States, United States
| | - Ya-Yu Hu
- Department of Neuroscience, University of Texas at Dallas, Texas, United States
- School of Behavioral and Brain Science, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, United States, United States
| | - Soneet Kapadia
- School of Behavioral and Brain Science, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, United States, United States
- Department of Biology and Biochemistry, University of Texas at Dallas, Texas, United States
| | | | | | - Gregory Dussor
- Department of Neuroscience, University of Texas at Dallas, Texas, United States
- School of Behavioral and Brain Science, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, United States, United States
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Alvarez-Perez B, Poras H, Maldonado R. The inhibition of enkephalin catabolism by dual enkephalinase inhibitor: A novel possible therapeutic approach for opioid use disorders. Br J Pharmacol 2023; 180:879-893. [PMID: 34378790 DOI: 10.1111/bph.15656] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 07/14/2021] [Accepted: 07/28/2021] [Indexed: 11/30/2022] Open
Abstract
Despite the increasing impact of opioid use disorders on society, there is a disturbing lack of effective medications for their clinical management. An interesting innovative strategy to treat these disorders consists in the protection of endogenous opioid peptides to activate opioid receptors, avoiding the classical opioid-like side effects. Dual enkephalinase inhibitors (DENKIs) physiologically activate the endogenous opioid system by inhibiting the enzymes responsible for the breakdown of enkephalins, protecting endogenous enkephalins and increasing their half-lives and physiological actions. The activation of opioid receptors by the increased enkephalin levels, and their well-demonstrated safety, suggests that DENKIs could represent a novel analgesic therapy and a possible effective treatment for acute opioid withdrawal, as well as a promising alternative to opioid substitution therapy minimizing side effects. This new pharmacological class of compounds could bring effective and safe medications avoiding the major limitations of exogenous opioids, representing a novel approach to overcome the problem of opioid use disorders. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.
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Affiliation(s)
- Beltran Alvarez-Perez
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | | | - Rafael Maldonado
- Laboratory of Neuropharmacology, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
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3
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Margolis EB, Moulton MG, Lambeth PS, O'Meara MJ. The life and times of endogenous opioid peptides: Updated understanding of synthesis, spatiotemporal dynamics, and the clinical impact in alcohol use disorder. Neuropharmacology 2023; 225:109376. [PMID: 36516892 PMCID: PMC10548835 DOI: 10.1016/j.neuropharm.2022.109376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/03/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
The opioid G-protein coupled receptors (GPCRs) strongly modulate many of the central nervous system structures that contribute to neurological and psychiatric disorders including pain, major depressive disorder, and substance use disorders. To better treat these and related diseases, it is essential to understand the signaling of their endogenous ligands. In this review, we focus on what is known and unknown about the regulation of the over two dozen endogenous peptides with high affinity for one or more of the opioid receptors. We briefly describe which peptides are produced, with a particular focus on the recently proposed possible synthesis pathways for the endomorphins. Next, we describe examples of endogenous opioid peptide expression organization in several neural circuits and how they appear to be released from specific neural compartments that vary across brain regions. We discuss current knowledge regarding the strength of neural activity required to drive endogenous opioid peptide release, clues about how far peptides diffuse from release sites, and their extracellular lifetime after release. Finally, as a translational example, we discuss the mechanisms of action of naltrexone (NTX), which is used clinically to treat alcohol use disorder. NTX is a synthetic morphine analog that non-specifically antagonizes the action of most endogenous opioid peptides developed in the 1960s and FDA approved in the 1980s. We review recent studies clarifying the precise endogenous activity that NTX prevents. Together, the works described here highlight the challenges and opportunities the complex opioid system presents as a therapeutic target.
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Affiliation(s)
- Elyssa B Margolis
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA; Neuroscience Graduate Program, University of California, San Francisco, CA, USA.
| | - Madelyn G Moulton
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Philip S Lambeth
- UCSF Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, CA, USA
| | - Matthew J O'Meara
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA
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4
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Reply to Zhuang et al.: Potential side effects of positive allosteric modulators of the mu-opioid receptor. Proc Natl Acad Sci U S A 2021; 118:2108493118. [PMID: 34260391 DOI: 10.1073/pnas.2108493118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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5
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An Effective and Safe Enkephalin Analog for Antinociception. Pharmaceutics 2021; 13:pharmaceutics13070927. [PMID: 34206631 PMCID: PMC8308721 DOI: 10.3390/pharmaceutics13070927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 11/17/2022] Open
Abstract
Opioids account for 69,000 overdose deaths per annum worldwide and cause serious side effects. Safer analgesics are urgently needed. The endogenous opioid peptide Leu-Enkephalin (Leu-ENK) is ineffective when introduced peripherally due to poor stability and limited membrane permeability. We developed a focused library of Leu-ENK analogs containing small hydrophobic modifications. N-pivaloyl analog KK-103 showed the highest binding affinity to the delta opioid receptor (68% relative to Leu-ENK) and an extended plasma half-life of 37 h. In the murine hot-plate model, subcutaneous KK-103 showed 10-fold improved anticonception (142%MPE·h) compared to Leu-ENK (14%MPE·h). In the formalin model, KK-103 reduced the licking and biting time to ~50% relative to the vehicle group. KK-103 was shown to act through the opioid receptors in the central nervous system. In contrast to morphine, KK-103 was longer-lasting and did not induce breathing depression, physical dependence, and tolerance, showing potential as a safe and effective analgesic.
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Szymaszkiewicz A, Storr M, Fichna J, Zielinska M. Enkephalinase inhibitors, potential therapeutics for the future treatment of diarrhea predominant functional gastrointestinal disorders. Neurogastroenterol Motil 2019; 31:e13526. [PMID: 30549162 DOI: 10.1111/nmo.13526] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/20/2018] [Accepted: 11/12/2018] [Indexed: 02/08/2023]
Abstract
The endogenous opioid system (EOS) is considered being a crucial element involved in the pathophysiology of irritable bowel syndrome (IBS) as it regulates gastrointestinal (GI) homeostasis through modulation of motility and water and ion secretion/absorption. Along with opioid receptors (ORs), the following components of EOS can be distinguished: 1. endogenous opioid peptides (EOPs), namely enkephalins, endorphins, endomorphins and dynorphins, and 2. peptidases, which regulate the metabolism (synthesis and degradation) of EOPs. Enkephalins, which are δ-opioid receptors agonists, induce significant effects in the GI tract as they act as potent pro-absorptive neurotransmitters. The action of enkephalins and other EOPs is limited, since EOPs are easily and rapidly inactivated by a natural metalloendopeptidase (enkephalinase/neprilysin) and aminopeptidase N. Studies show that the activity of EOPs can be enhanced by inhibition of these enzymes. In this review, we discuss the antidiarrheal and antinociceptive potential of enkephalinase inhibitors. Furthermore, our review is to answer the question whether enkephalinase inhibitors may be helpful in the future treatment of diarrhea predominant functional GI disorders.
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Affiliation(s)
- Agata Szymaszkiewicz
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Martin Storr
- Department of Medicine, Ludwig Maximilians University Munich, Munich, Germany.,Center of Endoscopy, Starnberg, Germany
| | - Jakub Fichna
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Marta Zielinska
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
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Livingston KE, Traynor JR. Allostery at opioid receptors: modulation with small molecule ligands. Br J Pharmacol 2018; 175:2846-2856. [PMID: 28419415 PMCID: PMC6016636 DOI: 10.1111/bph.13823] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/31/2017] [Accepted: 04/04/2017] [Indexed: 12/14/2022] Open
Abstract
Opioid receptors are 7-transmembrane domain receptors that couple to heterotrimeric G proteins. The endogenous ligands for opioid receptors are peptides which bind to the orthosteric site on the receptors. The μ-opioid receptor is the target for opioid analgesics, while the δ-opioid receptor has been suggested as a target for pain management, migraine and depression. Similarly, κ-opioid receptors are involved in pain and depression and nociceptin receptors in pain and mood behaviours. However, exogenous orthosteric ligands for opioid receptors cause a myriad of on-target side effects. Recently, selective allosteric ligands for μ- and δ-opioid receptors have been described. These compounds bind to a site on the receptor distinct from the orthosteric site. Occupation of this allosteric site leads to modulation of orthosteric ligand binding affinity and/or efficacy. Allosteric modulators may be positive, negative or silent (neutral) (PAMs, NAMs or SAMs respectively). PAMs may have in vivo activity by enhancing the activity of exogenous drugs or endogenous opioid peptides. Enhancing endogenous opioid peptide activity maintains the temporal and spatial distribution of these molecules but improves, and potentially qualitatively changes, activity at their cognate receptors which could limit side effects compared with traditional opioid drugs. In this review, we describe the rationale and promise for the development of allosteric modulators for opioid receptors, the discovery of selective allosteric modulators, the identification of potential allosteric sites on opioid receptors and the mode of action of the modulators. LINKED ARTICLES This article is part of a themed section on Emerging Areas of Opioid Pharmacology. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.14/issuetoc.
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Affiliation(s)
| | - John R Traynor
- Department of PharmacologyUniversity of Michigan Medical SchoolAnn ArborMIUSA
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8
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Noble F, Marie N. Management of Opioid Addiction With Opioid Substitution Treatments: Beyond Methadone and Buprenorphine. Front Psychiatry 2018; 9:742. [PMID: 30713510 PMCID: PMC6345716 DOI: 10.3389/fpsyt.2018.00742] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 12/14/2018] [Indexed: 12/13/2022] Open
Abstract
With the opioid crisis in North America, opioid addiction has come in the spotlight and reveals the weakness of the current treatments. Two main opioid substitution therapies (OST) exist: buprenorphine and methadone. These two molecules are mu opioid receptor agonists but with different pharmacodynamic and pharmacokinetic properties. In this review, we will go through these properties and see how they could explain why these medications are recognized for their efficacy in treating opioid addiction but also if they could account for the side effects especially for a long-term use. From this critical analysis, we will try to delineate some guidelines for the design of future OST.
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Affiliation(s)
- Florence Noble
- CNRS ERL 3649, "Neuroplasticité et thérapies des addictions", Paris, France.,INSERM UMR-S 1124, Paris, France.,Centre Universitaire des Saints Pères, Université Paris Descartes, Paris, France
| | - Nicolas Marie
- CNRS ERL 3649, "Neuroplasticité et thérapies des addictions", Paris, France.,INSERM UMR-S 1124, Paris, France.,Centre Universitaire des Saints Pères, Université Paris Descartes, Paris, France
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9
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Bonnard E, Poras H, Fournié-Zaluski MC, Roques BP. Preventive and alleviative effects of the dual enkephalinase inhibitor (Denki) PL265 in a murine model of neuropathic pain. Eur J Pharmacol 2016; 788:176-182. [DOI: 10.1016/j.ejphar.2016.05.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 11/24/2022]
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10
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Tambaro S, Reali R, Volonterio A, Zanda M, Olimpieri F, Pinna GA, Lazzari P. NESS002ie: A new fluorinated thiol endopeptidase inhibitor with antinociceptive activity in an animal model of persistent pain. Pharmacol Biochem Behav 2013; 110:137-44. [DOI: 10.1016/j.pbb.2013.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/22/2013] [Accepted: 06/18/2013] [Indexed: 11/16/2022]
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11
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Semicarbazide Substitution Enhances Enkephalins Resistance to Ace Induced Hydrolysis. Int J Pept Res Ther 2012. [DOI: 10.1007/s10989-012-9306-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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12
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Inhibiting the breakdown of endogenous opioids and cannabinoids to alleviate pain. Nat Rev Drug Discov 2012; 11:292-310. [DOI: 10.1038/nrd3673] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Jutkiewicz EM. RB101-mediated protection of endogenous opioids: potential therapeutic utility? CNS DRUG REVIEWS 2007; 13:192-205. [PMID: 17627672 PMCID: PMC6726351 DOI: 10.1111/j.1527-3458.2007.00011.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The endogenous opioids met- and leu-enkephalin are inactivated by peptidases preventing the activation of opioid receptors. Inhibition of enkephalin-degrading enzymes increases endogenous enkephalin levels and stimulates robust behavioral effects. RB101, an inhibitor of enkephalin-degrading enzymes, produces antinociceptive, antidepressant, and anxiolytic effects in rodents, without typical opioid-related negative side effects. Although enkephalins are not selective endogenous ligands, RB101 induces these behaviors through receptor-selective activity. The antinociceptive effects of RB101 are produced through either the mu-opioid receptor alone or through activation of both mu- and delta-opioid receptors; the antidepressant-like and anxiolytic effects of RB101 are mediated only through the delta-opioid receptor. Although little is known about the effects of RB101 on other physiologically and behaviorally relevant peptides, these findings suggest that RB101 and other inhibitors of enkephalin-degrading enzymes may have potential as novel therapeutic compounds for the treatment of pain, depression, and anxiety.
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Affiliation(s)
- Emily M Jutkiewicz
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0632, USA.
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Noble F, Roques BP. Protection of endogenous enkephalin catabolism as natural approach to novel analgesic and antidepressant drugs. Expert Opin Ther Targets 2007; 11:145-59. [PMID: 17227231 DOI: 10.1517/14728222.11.2.145] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The most efficient drugs to alleviate severe pain are opioid compounds. However, their chronic use could be associated with serious drawbacks, such as tolerance, respiratory depression and constipation. Therefore, there is a need for compounds able to efficiently alleviate inflammatory and neurogenic pain following chronic treatment. The discovery that the endogenous opioid peptides, enkephalins, are inactivated by two metallopeptidases, neutral endopeptidase and aminopeptidase N, which can be blocked by synthetic dual inhibitors, represents a promising way to develop 'physiological' analgesics devoid of morphine side effects. These dual inhibitors also have antidepressant-like properties through enkephalin-related activation of delta-opioid receptors. This is expected to reduce the emotional component of pain in humans. This article reviews the promising data obtained for future development of a new class of analgesic that could be of major interest in a number of severe and chronic pain syndromes.
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Abstract
Despite significant improvements in our ability to treat neuropathic pain, we are far from the situation of being able to guarantee pain relief. The next few years promise to see the introduction of novel pharmacologic entities that show potential in the field of neuropathic pain treatment. Allied to this will be the realization that some drugs originally released for nonpain indications in fact have an analgesic effect in neuropathic pain. Our treatment armamentarium will be further enhanced by the release of currently available agents with proven efficacy but in new formulations. However, not every product of our improved knowledge will manifest as a new drug treatment for neuropathic pain. Despite evidence of efficacy, some drugs will fail to reach commercialization due to the lack of investment in their clinical development.
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Affiliation(s)
- Gary McCleane
- Rampark Pain Centre, 2 Rampark, Dromore Road, Lurgan, BT66 7JH, Northern Ireland, UK.
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16
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Le Guen S, Mas Nieto M, Canestrelli C, Chen H, Fournié-Zaluski MC, Cupo A, Maldonado R, Roques BP, Noble F. Pain management by a new series of dual inhibitors of enkephalin degrading enzymes: long lasting antinociceptive properties and potentiation by CCK2 antagonist or methadone. Pain 2003; 104:139-48. [PMID: 12855323 DOI: 10.1016/s0304-3959(02)00486-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The discovery that the endogenous morphine-like peptides named enkephalins are inactivated by two metallopeptidases, neutral endopeptidase and aminopeptidase N, which can be blocked by dual inhibitors, represents a promising way to develop 'physiological' analgesics devoid of the side effects of morphine. A new series of dual aminophosphinic inhibitors of the two enkephalin-catabolizing enzymes has been recently designed. In this study, one of these inhibitors, RB3007, was tested in various assays commonly used to select analgesics (mouse hot-plate test, rat tail-flick test, writhing and formalin tests in mice, and paw pressure test in rats), and the extracellular levels of the endogenous enkephalins in the ventrolateral periaqueductal grey have been measured by microdialysis after systemic administration of RB3007. In the mouse hot-plate test, the dual inhibitor induced long-lasting (2 h) antinociceptive effects with a maximum of 35% analgesia 60 min after i.v. or i.p. administration. These antinociceptive responses were antagonized by prior injection of naloxone (0.1 mg/kg, s.c.). Similar long lasting effects were observed in the other animal models used. Very interestingly, injection of RB3007 (50 mg/kg, i.p.) significantly increased (82%) the extracellular levels of Met-enkephalin with a peak 60 min after i.p. injection. This increase parallels the antinociceptive responses observed. In addition, strong facilitatory effects of subanalgesic doses of the CCK(2) receptor antagonist, PD-134,308 or the synthetic opioid agonist, methadone on RB3007-induced antinociceptive responses were observed. These findings may constitute promising data for future development of a new class of analgesics that could be of major interest in a number of severe and persistent pain syndromes.
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Affiliation(s)
- Stéphanie Le Guen
- Département de Pharmacochimie Moléculaire et Structurale, INSERM U266, CNRS FRE2463, UFR des Sciences Pharmaceutiques et Biologiques, 4 Avenue de l'Observatoire, 75270 Paris Cedex 06, France.
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Abstract
This paper is the twenty-fourth installment of the annual review of research concerning the opiate system. It summarizes papers published during 2001 that studied the behavioral effects of the opiate peptides and antagonists. The particular topics covered this year include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology(Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Benoist JM, Keime F, Montagne J, Noble F, Fournié-Zaluski MC, Roques BP, Willer JC, Le Bars D. Depressant effect on a C-fibre reflex in the rat, of RB101, a dual inhibitor of enkephalin-degrading enzymes. Eur J Pharmacol 2002; 445:201-10. [PMID: 12079685 DOI: 10.1016/s0014-2999(02)01753-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of N-[(R,S)-2-benzyl-3[(S)-(2-amino-4-methylthio)butyldithiol]-1-oxopropyl]-L-phenylalanine benzyl ester (RB101), a dual inhibitor of the enkephalin-degrading enzymes, neutral endopeptidase and aminopeptidase N, was assessed in anaesthetised rats on the C-fibre reflex elicited by electrical stimulation within the sural nerve territory and recorded from the ipsilateral biceps femoris muscle. The temporal evolution of the pharmacological response was monitored by the repeated application of a constant stimulus intensity, namely three times threshold (3 T). In addition, recruitment curves were built by varying the stimulus intensity from 0 to 7 T. RB101 (7.5, 15 and 30 mg kg(-1), i.v.) induced a dose-dependent, naloxone-reversible depression of the reflex, which lasted around 60 min with the highest dose. The ED(50) was calculated as 16.9 mg kg(-1). Analyses of the recruitment curves revealed: (1) a significant increase of threshold; (2) a significant depression of the reflex in the ascending part of the curve; and (3) a lack of major depressive effects on the responses elicited by the strongest stimuli (corresponding to the plateau of the curve). The increase in the nociceptive threshold by enkephalin-degrading enzyme inhibitors, confirms previous data obtained from behavioural tests. In addition, the present study revealed an efficacy of these compounds over a wide range of stimulus intensities, albeit excluding the highest.
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Affiliation(s)
- Jean-Michel Benoist
- Laboratoire de Physiopharmacologie du Système nerveux, INSERM U161, 2 rue d'Alésia, 75014 Paris Cedex, France
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Chen H, Noble F, Roques BP, Fournié-Zaluski MC. Long lasting antinociceptive properties of enkephalin degrading enzyme (NEP and APN) inhibitor prodrugs. J Med Chem 2001; 44:3523-30. [PMID: 11585456 DOI: 10.1021/jm0102248] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Prodrugs of phosphinic dual inhibitors of the enkephalin degrading enzymes, neutral endopeptidase (NEP) and aminopeptidase N (APN), corresponding to the formula H(3)N(+)CH(R(1))P(O)(OR)CH(2)CH(CH(2)Bip)CONHCH(CH(3))COOCH(2)Ph, with R(1) = CH(3) or Ph and R being a benzyl ester, a S-acyl-2-thioethyl derivative, or an acyloxyalkyl group, were synthesized to improve the poor central bioavailability of their precursors. As expected, these compounds (50 mg/kg, iv or ip) induced long lasting ( approximately 2 h) antinociceptive responses in the hot plate test in mice with a ceiling effect varying between 25 and 42% of analgesia. A very rapid hydrolysis of the carboxylate ester contrasting with a slow deprotection of the phosphinate group (t(1/2) approximately 1 h) was observed in serum while 80% of free drug was obtained after 1 h incubation with brain membranes. These results account for the long duration of action observed with these prodrugs.
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Affiliation(s)
- H Chen
- Département de Pharmacochimie Moléculaire et Structurale, INSERM U266, CNRS UMR 8600, Paris Cedex 06, France
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Nieto MM, Wilson J, Walker J, Benavides J, Fournié-Zaluski MC, Roques BP, Noble F. Facilitation of enkephalins catabolism inhibitor-induced antinociception by drugs classically used in pain management. Neuropharmacology 2001; 41:496-506. [PMID: 11543770 DOI: 10.1016/s0028-3908(01)00077-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The aim of this study was to investigate the facilitatory effects of subanalgesic or low doses of different drugs (acetylsalicylic acid, ibuprofen and morphine) on the antinociceptive responses induced by the endogenous opioid peptides, enkephalins, protected from their catabolism by the dual enkephalin-degrading enzymes inhibitor RB101. According to the analgesic profile of the three studied compounds different antinociceptive assays were used: the hot plate and formalin tests in mice, and the tail flick and paw pressure tests on inflamed paws in rats and polyarthritic rats. Facilitatory effects of subanalgesic doses of acetylsalicylic acid and ibuprofen on RB101-induced antinociceptive responses were observed in the early and late phases of the formalin test, respectively. In the hot plate, tail flick and paw pressure tests, the dose-dependent analgesic effects of RB101 were strongly potentiated by subanalgesic doses of morphine (0.5 mg/kg), while in these tests, acetylsalicylic acid and ibuprofen were unable to modify the RB101-induced antinociceptive responses. The synergism in antinociceptive effects observed with the combination of RB101 and morphine supported by isobolographic analysis, may have interesting clinical implications, considering both the lack of opiate drawbacks observed with RB101 and the high potentiation of its antinociceptive effects with very low doses of morphine.
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Affiliation(s)
- M M Nieto
- Département de Pharmacochimie Moléculaire et Structurale, INSERM U266-CNRS UMR 8600, Université René Descartes, 4, Avenue de l'Observatoire, 75270 Paris Cedex 06, France
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