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Discovery of Novel Delta Opioid Receptor (DOR) Inverse Agonist and Irreversible (Non-Competitive) Antagonists. Molecules 2021; 26:molecules26216693. [PMID: 34771099 PMCID: PMC8587863 DOI: 10.3390/molecules26216693] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 02/03/2023] Open
Abstract
The delta opioid receptor (DOR) is a crucial receptor system that regulates pain, mood, anxiety, and similar mental states. DOR agonists, such as SNC80, and DOR-neutral antagonists, such as naltrindole, were developed to investigate the DOR in vivo and as potential therapeutics for pain and depression. However, few inverse agonists and non-competitive/irreversible antagonists have been developed, and none are widely available. This leaves a gap in our pharmacological toolbox and limits our ability to investigate the biology of this receptor. Thus, we designed and synthesized the novel compounds SRI-9342 as an irreversible antagonist and SRI-45128 as an inverse agonist. These compounds were then evaluated in vitro for their binding affinity by radioligand binding, their functional activity by 35S-GTPγS coupling, and their cAMP accumulation in cells expressing the human DOR. Both compounds demonstrated high binding affinity and selectivity at the DOR, and both displayed their hypothesized molecular pharmacology of irreversible antagonism (SRI-9342) or inverse agonism (SRI-45128). Together, these results demonstrate that we have successfully designed new inverse agonists and irreversible antagonists of the DOR based on a novel chemical scaffold. These new compounds will provide new tools to investigate the biology of the DOR or even new potential therapeutics.
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Mansour A, Nagi K, Dallaire P, Lukasheva V, Le Gouill C, Bouvier M, Pineyro G. Comprehensive Signaling Profiles Reveal Unsuspected Functional Selectivity of δ-Opioid Receptor Agonists and Allow the Identification of Ligands with the Greatest Potential for Inducing Cyclase Superactivation. ACS Pharmacol Transl Sci 2021; 4:1483-1498. [PMID: 34661070 PMCID: PMC8506601 DOI: 10.1021/acsptsci.1c00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Indexed: 11/29/2022]
Abstract
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Prolonged exposure
to opioid receptor agonists triggers adaptations
in the adenylyl cyclase (AC) pathway that lead to enhanced production
of cyclic adenosine monophosphate (cAMP) upon withdrawal. This cellular
phenomenon contributes to withdrawal symptoms, hyperalgesia and analgesic
tolerance that interfere with clinical management of chronic pain
syndromes. Since δ-opioid receptors (DOPrs) are a promising
target for chronic pain management, we were interested in finding
out if cell-based signaling profiles as generated for drug discovery
purposes could inform us of the ligand potential to induce sensitization
of the cyclase path. For this purpose, signaling of DOPr agonists
was monitored at multiple effectors. The resulting signaling profiles
revealed marked functional selectivity, particularly for Met-enkephalin
(Met-ENK) whose signaling bias profile differed from those of synthetic
ligands like SNC-80 and ARM390. Signaling diversity among ligands
was systematized by clustering agonists according to similarities
in Emax and Log(τ) values for the
different responses. The classification process revealed that the
similarity in Gα/Gβγ, but not in β-arrestin
(βarr), responses was correlated with the potential of Met-ENK,
deltorphin II, (d-penicillamine2,5)-enkephalin (DPDPE), ARM390,
and SNC-80 to enhance cAMP production, all of which required Ca2+ mobilization to produce this response. Moreover, superactivation
by Met-ENK, which was the most-effective Ca2+ mobilizing
agonist, required Gαi/o activation, availability of Gβγ
subunits at the membrane, and activation of Ca2+ effectors
such as calmodulin and protein kinase C (PKC). In contrast, superactivation by (N-(l-tyrosyl)-(3S)-1,2,3,4-tetrahydroisoquinoline-3-carbonyl)-l-phenylalanyl-l-phenylalanine (TIPP), which was set
in a distinct category through clustering, required activation of
Gαi/o subunits but was independent of the Gβγ dimer
and Ca2+ mobilization, relying instead on Src and Raf-1
to induce this cellular adaptation.
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Affiliation(s)
- Ahmed Mansour
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada.,CHU Sainte-Justine Research Center, Montréal, Quebec H3T 1C5, Canada
| | - Karim Nagi
- College of Medicine, QU Health, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Paul Dallaire
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada.,CHU Sainte-Justine Research Center, Montréal, Quebec H3T 1C5, Canada
| | - Viktoriya Lukasheva
- Institute for Research in Immunology and Cancer, Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Christian Le Gouill
- Institute for Research in Immunology and Cancer, Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Michel Bouvier
- Institute for Research in Immunology and Cancer, Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada
| | - Graciela Pineyro
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montréal, Montréal, Quebec H3T 1J4, Canada.,CHU Sainte-Justine Research Center, Montréal, Quebec H3T 1C5, Canada
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3
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Hirayama S, Fujii H. δ Opioid Receptor Inverse Agonists and their In Vivo Pharmacological Effects. Curr Top Med Chem 2020; 20:2889-2902. [PMID: 32238139 DOI: 10.2174/1568026620666200402115654] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/25/2020] [Accepted: 03/05/2020] [Indexed: 11/22/2022]
Abstract
The discovery of δ opioid receptor inverse agonist activity induced by ICI-174,864, which was previously reported as an δ opioid receptor antagonist, opened the door for the investigation of inverse agonism/constitutive activity of the receptors. Various peptidic or non-peptidic δ opioid receptor inverse agonists have since been developed. Compared with the reports dealing with in vitro inverse agonist activities of novel compounds or known compounds as antagonists, there have been almost no publications describing the in vivo pharmacological effects induced by a δ opioid receptor inverse agonist. After the observation of anorectic effects with the δ opioid receptor antagonism was discussed in the early 2000s, the short-term memory improving effects and antitussive effects have been very recently reported as possible pharmacological effects induced by a δ opioid receptor inverse agonist. In this review, we will survey the developed δ opioid receptor inverse agonists and summarize the possible in vivo pharmacological effects by δ opioid receptor inverse agonists. Moreover, we will discuss important issues involved in the investigation of the in vivo pharmacological effects produced by a δ opioid receptor inverse agonist.
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Affiliation(s)
- Shigeto Hirayama
- Laboratory of Medicinal Chemistry and Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5- 9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Hideaki Fujii
- Laboratory of Medicinal Chemistry and Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5- 9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
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Hirayama S, Iwai T, Higashi E, Nakamura M, Iwamatsu C, Itoh K, Nemoto T, Tanabe M, Fujii H. Discovery of δ Opioid Receptor Full Inverse Agonists and Their Effects on Restraint Stress-Induced Cognitive Impairment in Mice. ACS Chem Neurosci 2019; 10:2237-2242. [PMID: 30913383 DOI: 10.1021/acschemneuro.9b00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The cyclopropylmethyl group in classical δ opioid receptor (DOR) antagonist NTI, BNTX, and NTB was replaced with various electron-withdrawing groups to develop DOR inverse agonists. N-Benzyl NTB derivative SYK-657 was a potent DOR full inverse agonist and its potency was over 10-fold potent than that of a reference compound ICI-174,864. Intraperitoneal administration of SYK-657 induced the short-term memory improving effect in mice without abnormal behaviors.
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Affiliation(s)
- Shigeto Hirayama
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Takashi Iwai
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
- Laboratory of Pharmacology, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Eika Higashi
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Minami Nakamura
- Laboratory of Pharmacology, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Chiharu Iwamatsu
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Kennosuke Itoh
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Toru Nemoto
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Mitsuo Tanabe
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
- Laboratory of Pharmacology, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
| | - Hideaki Fujii
- Laboratory of Medicinal Chemistry, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
- Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1, Shirokane,
Minato-ku, Tokyo 108-8641, Japan
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5
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Gendron L, Cahill CM, von Zastrow M, Schiller PW, Pineyro G. Molecular Pharmacology of δ-Opioid Receptors. Pharmacol Rev 2017; 68:631-700. [PMID: 27343248 DOI: 10.1124/pr.114.008979] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Opioids are among the most effective analgesics available and are the first choice in the treatment of acute severe pain. However, partial efficacy, a tendency to produce tolerance, and a host of ill-tolerated side effects make clinically available opioids less effective in the management of chronic pain syndromes. Given that most therapeutic opioids produce their actions via µ-opioid receptors (MOPrs), other targets are constantly being explored, among which δ-opioid receptors (DOPrs) are being increasingly considered as promising alternatives. This review addresses DOPrs from the perspective of cellular and molecular determinants of their pharmacological diversity. Thus, DOPr ligands are examined in terms of structural and functional variety, DOPrs' capacity to engage a multiplicity of canonical and noncanonical G protein-dependent responses is surveyed, and evidence supporting ligand-specific signaling and regulation is analyzed. Pharmacological DOPr subtypes are examined in light of the ability of DOPr to organize into multimeric arrays and to adopt multiple active conformations as well as differences in ligand kinetics. Current knowledge on DOPr targeting to the membrane is examined as a means of understanding how these receptors are especially active in chronic pain management. Insight into cellular and molecular mechanisms of pharmacological diversity should guide the rational design of more effective, longer-lasting, and better-tolerated opioid analgesics for chronic pain management.
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Affiliation(s)
- Louis Gendron
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Catherine M Cahill
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Mark von Zastrow
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Peter W Schiller
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
| | - Graciela Pineyro
- Département de Pharmacologie-Physiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Centre de Recherche du CHU de Sherbrooke, Centre d'excellence en neurosciences de l'Univeristé de Sherbrooke, and Institut de Pharmacologie de Sherbrooke, Sherbrooke, Quebec, Canada (L.G.); Québec Pain Research Network, Sherbrooke, Quebec, Canada (L.G.); Departments of Anesthesiology and Perioperative Care and Pharmacology, University of California, Irvine, California (C.M.C.); Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada (C.M.C.); Departments of Psychiatry and Cellular and Molecular Pharmacology, University of California, San Francisco, California (M.v.Z.); Laboratory of Chemical Biology and Peptide Research, Clinical Research Institute of Montréal, Montreal, Quebec, Canada (P.W.S.); and Departments of Psychiatry, Pharmacology, and Neurosciences, Faculty of Medicine, University of Montréal and Sainte-Justine Hospital Research Center, Montreal, Quebec, Canada (G.P.)
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6
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Naltrindole derivatives with fluorinated ethyl substituents on the 17-nitrogen as δ opioid receptor inverse agonists. Bioorg Med Chem Lett 2015; 25:2927-30. [DOI: 10.1016/j.bmcl.2015.05.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 05/13/2015] [Accepted: 05/18/2015] [Indexed: 11/21/2022]
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7
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Hong MH, Xu C, Wang YJ, Ji JL, Tao YM, Xu XJ, Chen J, Xie X, Chi ZQ, Liu JG. Role of Src in ligand-specific regulation of delta-opioid receptor desensitization and internalization. J Neurochem 2008; 108:102-14. [PMID: 19014372 DOI: 10.1111/j.1471-4159.2008.05740.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The opioid receptors are a member of G protein-coupled receptors that mediate physiological effects of endogenous opioid peptides and structurally distinct opioid alkaloids. Although it is well characterized that there is differential receptor desensitization and internalization properties following activation by distinct agonists, the underlying mechanisms remain elusive. We investigated the signaling events of delta-opioid receptor (deltaOR) initiated by two ligands, DPDPE and TIPP. We found that although both ligands inhibited adenylyl cyclase (AC) and activated ERK1/2, only DPDPE induced desensitization and internalization of the deltaOR. We further found that DPDPE, instead of TIPP, could activate GRK2 by phosphorylating the non-receptor tyrosine kinase Src and translocating it to membrane receptors. Activation of GRK2 led to the phosphorylation of serine residues in the C-terminal tail, which facilitates beta-arrestin1/2 membrane translocation. Meanwhile, we also found that DPDPE promoted beta-arrestin1 dephosphorylation in a Src-dependent manner. Thus, DPDPE appears to strengthen beta-arrestin function by dual regulations: promoting beta-arrestin recruitment and increasing beta-arrestin dephosphorylation at the plasma membrane in a Src-dependent manner. All effects initiated by DPDPE could be abolished or suppressed by PP2, an inhibitor of Src. Morphine, which has been previously shown to be unable to desensitize or internalize deltaOR, also behaved as TIPP in failure to utilize Src to regulate deltaOR signaling. These findings point to the existence of agonist-specific utilization of Src to regulate deltaOR signaling and reveal the molecular events by which Src modulates deltaOR responsiveness.
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Affiliation(s)
- Min-Hua Hong
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
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8
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Dupré DJ, Thompson C, Chen Z, Rollin S, Larrivée JF, Le Gouill C, Rola-Pleszczynski M, Stanková J. Inverse agonist-induced signaling and down-regulation of the platelet-activating factor receptor. Cell Signal 2007; 19:2068-79. [PMID: 17609120 DOI: 10.1016/j.cellsig.2007.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 05/25/2007] [Accepted: 05/28/2007] [Indexed: 11/16/2022]
Abstract
Platelet-activating factor (PAF) is a potent phospholipid mediator involved in several diseases such as allergic asthma, atherosclerosis and psoriasis. The human PAF receptor (PAFR) is a member of the G-protein-coupled receptor family. Following stimulation, PAFR becomes rapidly desensitized; this refractory state is dependent on PAFR phosphorylation, internalization and down-regulation. In this report, we show that the PAFR inverse agonist, WEB2086, can induce phosphorylation and down-regulation of PAFR. Using selective inhibitors, we determined that the agonist, PAF, and WEB2086 could induce phosphorylation of PAFR by PKC. Moreover, dominant-negative (DN) mutant of PKC isoforms beta inhibited WEB2086-stimulated PAFR phosphorylation, whereas PAF-stimulated phosphorylation was inhibited by DN PKCalpha and delta. WEB2086 also induced PAFR down-regulation which could be blocked by PKC inhibitors and by DN PKCbeta. WEB2086-induced down-regulation was dynamin-dependent but arrestin-independent. Unlike PAF, WEB2086-stimulated intracellular trafficking of PAFR was independent of Rab5. Specific inhibitors of lysosomal proteases and of proteasomes were both effective in reducing WEB2086-induced PAFR down-regulation, indicating the importance of receptor targeting to both lysosomes and proteasomes in long-term cell desensitization to WEB2086. These results indicate that although both agonists and inverse agonists induce receptor PAFR down-regulation, this may be accomplished through different signal transduction and trafficking pathways.
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Affiliation(s)
- Denis J Dupré
- Immunology Division, Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, 3001 12th Avenue North, Sherbrooke, Quebec, Canada
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9
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Ioja E, Tourwé D, Kertész I, Tóth G, Borsodi A, Benyhe S. Novel diastereomeric opioid tetrapeptides exhibit differing pharmacological activity profiles. Brain Res Bull 2007; 74:119-29. [PMID: 17683797 DOI: 10.1016/j.brainresbull.2007.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 05/12/2007] [Accepted: 05/16/2007] [Indexed: 11/28/2022]
Abstract
A novel opioid peptide antagonist analogue, [3H]Dmt-Tic-(2S,3R)betaMePhe-Phe, derived from the potent, delta-receptor selective TIPP tetrapeptide (Tyr-Tic-Phe-Phe) series was synthesized and radiolabeled by catalytic tritiation of its iodinated precursor peptide. The purified radioprobe exhibited a specific activity of 2.15 TBq/mmol (58 Ci/mmol). The novelty of this compound is that it contains structurally modified tyrosine residue (2',6'-dimethyltyrosine, Dmt1) replacing tyrosine (Tyr1) at the N-terminus, and beta-methyl substituted phenylalanine (betaMePhe3) at the third position. As the configuration of betaMePhe3 side-chain might be different due to diastereomerism, and accordingly can alter the biological activity, both unlabeled threo (2S,3R and 2R,3S) diastereomeric analogues were also prepared and included in this study. The affinity and selectivity (delta-opioid versus mu-opioid receptor) were evaluated by radioreceptor binding assays. Agonist or antagonist potencies were determined in [35S]GTPgammaS binding experiments using Chinese Hamster Ovary (CHO) cells selectively expressing delta- or mu-opioid receptors. The equilibrium binding of the radiolabeled peptide derivative [3H]Dmt-Tic-(2S,3R)betaMePhe-Phe to rat brain membranes was saturable and the Scatchard analysis indicated a single binding site with a Kd of 0.3 nM and a Bmax of 127 fmol/mg protein. A study of [3H]Dmt-Tic-(2S,3R)betaMePhe-Phe binding displacement by various receptor-type specific opioid ligands showed the rank order of competitor's potency delta > mu > kappa, suggesting selective labeling of opioid delta-sites. In the functional tests, the (2S,3R) and (2R,3S) peptides exhibited partial agonist behaviour by weakly stimulating regulatory G-proteins in CHO cell membranes transfected with different receptors. Both isomers were quite weak partial agonists at the delta-receptor and reasonable partial agonists at the mu-receptor, with a prevalence of (2S,3R) over (2R,3S) for the mu-receptor. Consistent with these observations both stereomers competitively inhibited the stimulation of [35S]GTPgammaS binding induced by the prototype delta-agonist peptide (pClPhe4)-DPDPE in delta(m) CHO cell membranes, and still the (2S,3R) compound exerted more potent delta-antagonist effect. [3H]Dmt-Tic-(2S,3R)betaMePhe-Phe represents a high affinity new radioligand and also constitute further example of the influence of beta-methyl substitution on the potency and selectivity of TIPP analogues, thus becoming a valuable biochemical and pharmacological tool in opioid research.
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Affiliation(s)
- Eniko Ioja
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvari krt. 62, H-6726 Szeged, Hungary
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10
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Ioja E, Tóth G, Benyhe S, Tourwe D, Péter A, Tömböly C, Borsodi A. Opioid receptor binding characteristics and structure-activity studies of novel tetrapeptides in the TIPP (Tyr-Tic-Phe-Phe) series. Neurosignals 2006; 14:317-28. [PMID: 16772734 DOI: 10.1159/000093046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Accepted: 03/06/2006] [Indexed: 11/19/2022] Open
Abstract
The development of the prototype synthetic delta-opioid receptor antagonist peptides TIPP [(H-Tyr-Tic-Phe- Phe-OH); Tic: tetrahydroisoquinoline-3-carboxylic acid] and TIPPpsi (H-Tyr-psiTic-Phe-Phe-OH) by Schiller and coworkers was followed by extensive structure-activity relationship studies, leading to the emergence of numerous analogs that are of pharmacological interest. Eight novel diastereomeric compounds in this peptide family were designed, prepared, and tested biologically to gain structure-activity relationship information. The new multisubstituted tetrapeptide analogs contain both a 2',6'-dimethyltyrosine residue at the N-terminus and beta-methyl-cyclohexylalanine at the third position as replacements for the original first tyrosine and the third phenylalanine, respectively. These derivatives wear either free acidic (-COOH) or amidated (-CONH2) C-terminal. The potency and delta- versus mu-opioid receptor selectivity were evaluated by in vitro radioreceptor-binding assays, while the intrinsic G-protein-activating efficacy of these analogs was tested in [35S]GTPgammaS-binding assays using rat brain membranes or Chinese hamster ovary cells stably expressing mu- or delta-opioid receptors. The analogs showed delta-antagonist selectivity with differences regarding their isomeric forms, and these analogs containing a C-terminal carboxamide group displayed a mixed mu-agonist/delta-antagonist profile, thus they are expected to be safer analgesics with a low propensity to produce tolerance and physical dependence. These results constitute further examples of the influence of beta-methyl substitution and C-terminal amidation on potency, selectivity, and signal transduction properties of TIPP-related peptides as well as they represent valuable pharmacological tools for opioid research.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- CHO Cells
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Cells, Cultured
- Cricetinae
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- In Vitro Techniques
- Molecular Conformation
- Oligopeptides/chemistry
- Oligopeptides/metabolism
- Oligopeptides/pharmacology
- Radioligand Assay
- Rats
- Rats, Wistar
- Receptors, Opioid/drug effects
- Receptors, Opioid/metabolism
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, mu/drug effects
- Structure-Activity Relationship
- Tetrahydroisoquinolines/chemistry
- Tetrahydroisoquinolines/metabolism
- Tetrahydroisoquinolines/pharmacology
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Affiliation(s)
- Eniko Ioja
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
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11
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Emmerson PJ, McKinzie JH, Surface PL, Suter TM, Mitch CH, Statnick MA. Na+ modulation, inverse agonism, and anorectic potency of 4-phenylpiperidine opioid antagonists. Eur J Pharmacol 2005; 494:121-30. [PMID: 15212965 DOI: 10.1016/j.ejphar.2004.04.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 04/28/2004] [Accepted: 04/30/2004] [Indexed: 10/26/2022]
Abstract
Differences in the anorectic activity of morphinan (e.g., naltrexone) and 3,4-dimethyl-4-(3-hydroxyphenyl)piperidine (4PP) opioid receptor antagonists have been described. In an attempt to explain these differences, the influence of Na(+) on opioid binding affinity and functional activity of 4PP antagonists was compared to other opioid antagonists. The binding affinities of neutral antagonists were unaffected by the addition of Na(+), whereas that for the peptide, inverse agonist N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH (ICI174864) was increased. Similarly, the binding affinities of the 4PP antagonist (3R,4R)-1-((S)-3-hydroxy-3-cyclohexylpropyl)-4-(3-hydroxyphenyl)-3,4-dimethyl-1-piperidine (LY255582) and other 4PP antagonists were increased in the presence of Na(+) with the greatest effects at the delta opioid receptor followed by the mu and kappa opioid receptors, respectively. Similar to ICI174864, 4PP antagonists were found to inhibit basal GTPgamma[(35)S] binding at the delta opioid receptor indicating inverse agonist activity. A correlation was observed between the binding affinities in the presence of Na(+), the inverse agonist potency, and the anorectic potency of 4PP antagonists. These data suggest that 4PP antagonists differ from morphinan antagonists in their inverse agonist activity and suggest a relationship between inverse agonism and anorectic activity.
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Affiliation(s)
- Paul J Emmerson
- Endocrine Research, Lilly Research Laboratories, Lilly Corporate Center DC0403, Indianapolis, IN 46285, USA
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12
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Tryoen-Tóth P, Décaillot FM, Filliol D, Befort K, Lazarus LH, Schiller PW, Schmidhammer H, Kieffer BL. Inverse agonism and neutral antagonism at wild-type and constitutively active mutant delta opioid receptors. J Pharmacol Exp Ther 2004; 313:410-21. [PMID: 15590769 DOI: 10.1124/jpet.104.077321] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The delta opioid receptor modulates nociceptive and emotional behaviors. This receptor has been shown to exhibit measurable spontaneous activity. Progress in understanding the biological relevance of this activity has been slow, partly due to limited characterization of compounds with intrinsic negative activity. Here, we have used constitutively active mutant (CAM) delta receptors in two different functional assays, guanosine 5'-O-(3-thio)triphosphate binding and a reporter gene assay, to test potential inverse agonism of 15 delta opioid compounds, originally described as antagonists. These include the classical antagonists naloxone, naltrindole, 7-benzylidene-naltrexone, and naltriben, a new set of naltrindole derivatives, H-Tyr-Tic-Phe-Phe-OH (TIPP) and H-Tyr-TicPsi[CH2N]Cha-Phe-OH [TICP(Psi)], as well as three 2',6'-dimethyltyrosine-1,2,3,4-tetrahydroquinoline-3-carboxylate (Dmt-Tic) peptides. A reference agonist, SNC 80 [(+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide], and inverse agonist, ICI 174864 (N,N-diallyl-Tyr-Aib-Aib-Phe-Leu), were also included. In a screen using wild-type and CAM M262T delta receptors, naltrindole (NTI) and close derivatives were mostly inactive, and TIPP behaved as an agonist, whereas Dmt-Tic-OH and N,N(CH3)2-Dmt-Tic-NH2 showed inverse agonism. The two latter compounds showed negative activity across 27 CAM receptors, suggesting that this activity was independent from the activation mechanism. These two compounds also exhibited nanomolar potencies in dose-response experiments performed on wild-type, M262T, Y308H, and C328R CAM receptors. TICP(Psi) exhibited strong inverse agonism at the Y308H receptor. We conclude that the stable N,N(CH3)2-Dmt-Tic-NH2 compound represents a useful tool to explore the spontaneous activity of delta receptors, and NTI and novel derivatives behave as neutral antagonists.
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Affiliation(s)
- P Tryoen-Tóth
- Institut de Génétique et Biologie Moléculaire et Cellulaire, 1 rue Laurent Fries, B.P. 1042, 67404 Illkirch Cedex, France
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13
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Barbier AJ, Berridge C, Dugovic C, Laposky AD, Wilson SJ, Boggs J, Aluisio L, Lord B, Mazur C, Pudiak CM, Langlois X, Xiao W, Apodaca R, Carruthers NI, Lovenberg TW. Acute wake-promoting actions of JNJ-5207852, a novel, diamine-based H3 antagonist. Br J Pharmacol 2004; 143:649-61. [PMID: 15466448 PMCID: PMC1575430 DOI: 10.1038/sj.bjp.0705964] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 07/13/2004] [Accepted: 07/21/2004] [Indexed: 11/08/2022] Open
Abstract
1 1-[4-(3-piperidin-1-yl-propoxy)-benzyl]-piperidine (JNJ-5207852) is a novel, non-imidazole histamine H3 receptor antagonist, with high affinity at the rat (pKi=8.9) and human (pKi=9.24) H3 receptor. JNJ-5207852 is selective for the H3 receptor, with negligible binding to other receptors, transporters and ion channels at 1 microm. 2 JNJ-5207852 readily penetrates the brain tissue after subcutaneous (s.c.) administration, as determined by ex vivo autoradiography (ED50 of 0.13 mg kg(-1) in mice). In vitro autoradiography with 3H-JNJ-5207852 in mouse brain slices shows a binding pattern identical to that of 3H-R-alpha-methylhistamine, with high specific binding in the cortex, striatum and hypothalamus. No specific binding of 3H-JNJ-5207852 was observed in brains of H3 receptor knockout mice. 3 In mice and rats, JNJ-5207852 (1-10 mg kg(-1) s.c.) increases time spent awake and decreases REM sleep and slow-wave sleep, but fails to have an effect on wakefulness or sleep in H3 receptor knockout mice. No rebound hypersomnolence, as measured by slow-wave delta power, is observed. The wake-promoting effects of this H3 receptor antagonist are not associated with hypermotility. 4 A 4-week daily treatment of mice with JNJ-5207852 (10 mg kg(-1) i.p.) did not lead to a change in body weight, possibly due to the compound being a neutral antagonist at the H3 receptor. 5 JNJ-5207852 is extensively absorbed after oral administration and reaches high brain levels. 6 The data indicate that JNJ-5207852 is a novel, potent and selective H3 antagonist with good in vitro and in vivo efficacy, and confirm the wake-promoting effects of H3 receptor antagonists.
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Affiliation(s)
- A J Barbier
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - C Berridge
- Department of Psychology, University of Wisconsin, WI, U.S.A
| | - C Dugovic
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL, U.S.A
| | - A D Laposky
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL, U.S.A
| | - S J Wilson
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - J Boggs
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - L Aluisio
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - B Lord
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - C Mazur
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - C M Pudiak
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - X Langlois
- Johnson & Johnson Pharmaceutical Research and Development, LLC, Beerse, Belgium
| | - W Xiao
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - R Apodaca
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - N I Carruthers
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
| | - T W Lovenberg
- Johnson & Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, U.S.A
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14
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Bryant SD, Jinsmaa Y, Salvadori S, Okada Y, Lazarus LH. Dmt and opioid peptides: a potent alliance. Biopolymers 2004; 71:86-102. [PMID: 12767112 DOI: 10.1002/bip.10399] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The introduction of the Dmt (2',6'-dimethyl-L-tyrosine)-Tic pharmacophore into the design of opioid ligands produced an extraordinary family of potent delta-opioid receptor antagonists and heralded a new phase in opioid research. First reviewed extensively in 1998, the incorporation of Dmt into a diverse group of opioid molecules stimulated the opioid field leading to the development of unique analogues with remarkable properties. This overview will document the crucial role played by this residue in the proliferation of opioid peptides with high receptor affinity (K(i) equal to or less than 1 nM) and potent bioactivity. The discussion will include the metamorphosis between delta-opioid receptor antagonists to delta-agonists based solely on subtle structural changes at the C-terminal region of the Dmt-Tic pharmacophore as well as their behavior in vivo. Dmt may be considered promiscuous due to the acquisition of potent mu-agonism by dermorphin and endomorphin derivatives as well as by a unique class of opioidmimetics containing two Dmt residues separated by alkyl or pyrazinone linkers. Structural studies on the Dmt-Tic compounds were enhanced tremendously by x-ray diffraction data for three potent and biologically diverse Dmt-Tic opioidmimetics that led to the development of pharmacophores for both delta-opioid receptor agonists and antagonists. Molecular modeling studies of other unique Dmt opioid analogues illuminated structural differences between delta- and mu-receptor ligand interactions. The future of these compounds as therapeutic applications for various medical syndromes including the control of cancer-associated pain is only a matter of time and perseverance.
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Affiliation(s)
- Sharon D Bryant
- Peptide Neurochemistry, LCBRA, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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15
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Engström M, Wurster S, Savola JM, Panula P. Functional properties of Pfr(Tic)amide and BIBP3226 at human neuropeptide FF2 receptors. Peptides 2003; 24:1947-54. [PMID: 15127947 DOI: 10.1016/j.peptides.2003.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The functional characteristics of two putative neuropeptide FF (NPFF) antagonists, BIBP3226 and PFR(Tic)amide, on the human neuropeptide FF receptor subtype 2 (hNPFF2) were investigated. Surprisingly, PFR(Tic)amide was shown to exhibit agonist properties in the [35S]guanosine-5'-O-(3-thio)triphosphate ([35S]GTPgammaS) binding assay. The efficacy of PFR(Tic)amide was significantly greater than that of (1DMe)Y8Fa, a stable analog of NPFF, and PFR(Tic)amide can therefore be classified as a 'super-agonist'. BIBP3226 did act as a reversible competitive antagonist on the hNPFF2 receptor. However, high concentrations of BIBP3226 also non-specifically increased [35S]GTP-gammaS binding. The usefulness of BIBP3226 as an antagonist tool on the NPFF receptor is thus limited.
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Affiliation(s)
- Mia Engström
- Juvantia Pharma Ltd, Lemminkäisenkatu 5,. Pharmacity, Turku FIN-20520, Finland.
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16
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Townsend D, Portoghese PS, Brown DR. Characterization of Specific Opioid Binding Sites in Neural Membranes from the Myenteric Plexus of Porcine Small Intestine. J Pharmacol Exp Ther 2003; 308:385-93. [PMID: 14569065 DOI: 10.1124/jpet.103.058016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Delta- and kappa-opioid receptors (OPRs), but not micro-OPRs, are expressed in the myenteric plexus of the porcine distal small intestine. In a subpopulation of myenteric neurons, delta- and kappa-OPRs seem to be colocalized and may functionally interact. In this study, radioligand binding was used to characterize myenteric OPR populations in detail. The nonselective OPR antagonist [3H]diprenorphine bound to a single, high-affinity site in myenteric neural membrane homogenates. Naloxone displaced 65 and 59% of [3H]diprenorphine binding from this site in Na(+)-free Tris and Krebs-HEPES buffers, respectively. Naltrexone-derived delta- and kappa-OPR antagonists, including naltriben, 7-benzylidenenaltrexone, nor-binaltorphimine, and 5'-guanidinonaltrindole, displaced [3H]diprenorphine from two distinct binding sites to levels similar to that of naloxone. The selective delta-OPR ligands Tyr-1,2,3,4-tetrahydroisoquinoline-Phe-Phe-OH (TIPP), [D-Pen2,D-Pen5]enkephalin (DPDPE), [D-Ala2, Glu4]deltorphin II, and (+)-4-[(alphaR)-alpha((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl-3-methoxybenzyl)-N,N-diethylbenzamide (SNC-80) and the kappa-OPR agonist (D-(5alpha,7alpha,8beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1-oxoaspiro-(4,5)dec-8-yl) benzeneacetamide (U-69,593) displaced [3H]diprenorphine from three independent binding sites; these included high-affinity delta- and kappa-OPR sites, and a residual binding site. Residual [3H]diprenorphine binding was displaced by the selective kappa-OPR antagonist nor-binaltorphimine after saturation of delta and kappa sites, respectively, with DPDPE and U-69,593. The residual binding site displayed low affinity for delta- and kappa-OPR agonists and TIPP, as well as moderate affinity for naltrexone-derived ligands, properties reminiscent of delta-/kappa-OPR heterodimers.
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MESH Headings
- Animals
- Binding Sites
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Diprenorphine/pharmacology
- Drug Interactions
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Female
- HEPES/metabolism
- Intestine, Small/cytology
- Male
- Myenteric Plexus/drug effects
- Myenteric Plexus/metabolism
- Narcotic Antagonists/pharmacology
- Narcotics/pharmacology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Sodium/metabolism
- Swine
- Tritium
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Affiliation(s)
- DeWayne Townsend
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota 55108-6010, USA
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17
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Abstract
This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 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 (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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18
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Liu JG, Prather PL. Chronic agonist treatment converts antagonists into inverse agonists at delta-opioid receptors. J Pharmacol Exp Ther 2002; 302:1070-9. [PMID: 12183665 DOI: 10.1124/jpet.102.035964] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In cellular models, chronic exposure to mu-opioid agonists converts antagonists into inverse agonists at mu-receptors. Such adaptations could contribute to the development of tolerance and/or dependence. To determine whether delta-receptors respond similarly, or whether this adaptation is unique for mu-receptors, this study examined the effects of prolonged agonist exposure on the intrinsic activity of several delta-opioid ligands in GH(3) cells expressing delta-receptors. In opioid naive cells, delta-receptors were constitutively active, and a series of delta-ligands displayed a range of intrinsic activities for G protein activation. Chronic treatment with the full delta-agonist [D-Pen(2,5)]-enkephalin reduced the acute ability of [D-Pen(2,5)]-enkephalin to stimulate and the full inverse agonist N,N-diallyl-Tyr-Aib-Aib-Phe-Leu-OH (ICI-174864) to inhibit G protein activation. In contrast, although naloxone and naltriben exhibited weak partial agonism in opioid naive cells, both ligands acted as full inverse agonists to produce concentration-dependent inhibition of guanosine 5'-O-(3-[(35)S]thio)triphosphate binding after prolonged exposure to [D-Pen(2,5)]-enkephalin or to the partial agonist morphine. This effect was reversed by a neutral delta-antagonist (N,N-bisallyl)-Tyr-Gly-Gly-psi-(CH(2)S)-Phe-Leu-OH (ICI-154129). Finally, as is also characteristic of inverse agonists, naloxone and naltriben demonstrated higher affinities for uncoupled delta-receptors in cells chronically treated with [D-Pen(2,5)]-enkephalin, relative to opioid naive cells. Therefore, this relatively novel adaptation is shared by both mu- and delta-opioid receptors and therefore may serve as an important common mechanism involved the development of tolerance and/or dependence.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Analgesics, Opioid/pharmacology
- Animals
- Cell Line
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Drug Tolerance
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Morphine/pharmacology
- Naloxone/pharmacology
- Naltrexone/analogs & derivatives
- Naltrexone/pharmacology
- Narcotic Antagonists/pharmacology
- Narcotics/pharmacology
- Opioid-Related Disorders/physiopathology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/antagonists & inhibitors
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Affiliation(s)
- Jing-Gen Liu
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA
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