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Sampaio-Dias IE, Reis-Mendes A, Costa VM, García-Mera X, Brea J, Loza MI, Pires-Lima BL, Alcoholado C, Algarra M, Rodríguez-Borges JE. Discovery of New Potent Positive Allosteric Modulators of Dopamine D 2 Receptors: Insights into the Bioisosteric Replacement of Proline to 3-Furoic Acid in the Melanostatin Neuropeptide. J Med Chem 2021; 64:6209-6220. [PMID: 33861612 DOI: 10.1021/acs.jmedchem.1c00252] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The control of Parkinson's disease (PD) is challenged by the motor and non-motor fluctuations as well as dyskinesias associated with levodopa long-term therapy. As such, pharmacological alternatives to reduce the reliance on this drug are needed. Melanostatin (MIF-1), a positive allosteric modulator (PAM) of D2 receptors (D2R), is being explored as a novel pharmacological approach focused on D2R potentiation. In this work, 3-furoic acid (3-Fu) was successfully employed as an l-proline (Pro) surrogate, affording two potent MIF-1 analogues, methyl 3-furoyl-l-leucylglycinate (4a) and 3-furoyl-l-leucylglycinamide (6a). In this series, the C-terminal carboxamide moiety was found crucial to enhancing the potency and toxicological profile, yet it is not considered a requisite for the PAM activity. Conformational analysis excludes 4a from adopting the claimed type II β-turn. The discovery and validation of 6a as a lead compound open a new avenue for the development of a novel class of anti-Parkinson therapeutics targeting the D2R.
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Affiliation(s)
- Ivo E Sampaio-Dias
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Ana Reis-Mendes
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Vera Marisa Costa
- UCIBIO, REQUIMTE, Laboratory of Toxicology, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Xerardo García-Mera
- Department of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - José Brea
- Innopharma Screening Platform, Biofarma Research group, Centre of Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - María Isabel Loza
- Innopharma Screening Platform, Biofarma Research group, Centre of Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Beatriz L Pires-Lima
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Cristina Alcoholado
- Department of Cellular Biology, Genetics and Physiology, Faculty of Sciences, University of Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - Manuel Algarra
- Department of Inorganic Chemistry, Faculty of Sciences, University of Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - José E Rodríguez-Borges
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
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2
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Sampaio-Dias IE, Rodríguez-Borges JE, Yáñez-Pérez V, Arrasate S, Llorente J, Brea JM, Bediaga H, Viña D, Loza MI, Caamaño O, García-Mera X, González-Díaz H. Synthesis, Pharmacological, and Biological Evaluation of 2-Furoyl-Based MIF-1 Peptidomimetics and the Development of a General-Purpose Model for Allosteric Modulators (ALLOPTML). ACS Chem Neurosci 2021; 12:203-215. [PMID: 33347281 DOI: 10.1021/acschemneuro.0c00687] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This work describes the synthesis and pharmacological evaluation of 2-furoyl-based Melanostatin (MIF-1) peptidomimetics as dopamine D2 modulating agents. Eight novel peptidomimetics were tested for their ability to enhance the maximal effect of tritiated N-propylapomorphine ([3H]-NPA) at D2 receptors (D2R). In this series, 2-furoyl-l-leucylglycinamide (6a) produced a statistically significant increase in the maximal [3H]-NPA response at 10 pM (11 ± 1%), comparable to the effect of MIF-1 (18 ± 9%) at the same concentration. This result supports previous evidence that the replacement of proline residue by heteroaromatic scaffolds are tolerated at the allosteric binding site of MIF-1. Biological assays performed for peptidomimetic 6a using cortex neurons from 19-day-old Wistar-Kyoto rat embryos suggest that 6a displays no neurotoxicity up to 100 μM. Overall, the pharmacological and toxicological profile and the structural simplicity of 6a makes this peptidomimetic a potential lead compound for further development and optimization, paving the way for the development of novel modulating agents of D2R suitable for the treatment of CNS-related diseases. Additionally, the pharmacological and biological data herein reported, along with >20 000 outcomes of preclinical assays, was used to seek a general model to predict the allosteric modulatory potential of molecular candidates for a myriad of target receptors, organisms, cell lines, and biological activity parameters based on perturbation theory (PT) ideas and machine learning (ML) techniques, abbreviated as ALLOPTML. By doing so, ALLOPTML shows high specificity Sp = 89.2/89.4%, sensitivity Sn = 71.3/72.2%, and accuracy Ac = 86.1%/86.4% in training/validation series, respectively. To the best of our knowledge, ALLOPTML is the first general-purpose chemoinformatic tool using a PTML-based model for the multioutput and multicondition prediction of allosteric compounds, which is expected to save both time and resources during the early drug discovery of allosteric modulators.
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Affiliation(s)
- Ivo E. Sampaio-Dias
- LAQV/REQUIMTE, Dept. of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - José E. Rodríguez-Borges
- LAQV/REQUIMTE, Dept. of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Víctor Yáñez-Pérez
- Dept. of Organic Chemistry II, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
| | - Sonia Arrasate
- Dept. of Pharmacology, Faculty of Medicine and Nursing, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
| | - Javier Llorente
- Dept. of Pharmacology, Faculty of Medicine and Nursing, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
- Dept. of Pharmacology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - José M. Brea
- Innopharma Screening Platform, Biofarma Research group, Centre of Research in Molecular Medicine and Chronic Diseases CIMUS, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Harbil Bediaga
- Dept. of Organic Chemistry II, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
- Dept. of Physical Chemistry, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
| | - Dolores Viña
- Dept. of Pharmacology, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
- Centre of Research in Molecular Medicine and Chronic Diseases CIMUS, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - María Isabel Loza
- Innopharma Screening Platform, Biofarma Research group, Centre of Research in Molecular Medicine and Chronic Diseases CIMUS, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Olga Caamaño
- Dept. of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Xerardo García-Mera
- Dept. of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Humberto González-Díaz
- Dept. of Organic Chemistry II, University of Basque Country (UPV-EHU), 48940 Leioa, Spain
- Basque Center for Biophysics (CSIC UPV/EHU), University of Basque Country (UPV-EHU), 48940 Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
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3
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Gibula-Tarlowska E, Kotlinska JH. Crosstalk between Opioid and Anti-Opioid Systems: An Overview and Its Possible Therapeutic Significance. Biomolecules 2020; 10:E1376. [PMID: 32998249 PMCID: PMC7599993 DOI: 10.3390/biom10101376] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/20/2020] [Accepted: 09/23/2020] [Indexed: 12/23/2022] Open
Abstract
Opioid peptides and receptors are broadly expressed throughout peripheral and central nervous systems and have been the subject of intense long-term investigations. Such studies indicate that some endogenous neuropeptides, called anti-opioids, participate in a homeostatic system that tends to reduce the effects of endogenous and exogenous opioids. Anti-opioid properties have been attributed to various peptides, including melanocyte inhibiting factor (MIF)-related peptides, cholecystokinin (CCK), nociceptin/orphanin FQ (N/OFQ), and neuropeptide FF (NPFF). These peptides counteract some of the acute effects of opioids, and therefore, they are involved in the development of opioid tolerance and addiction. In this work, the anti-opioid profile of endogenous peptides was described, mainly taking into account their inhibitory influence on opioid-induced effects. However, the anti-opioid peptides demonstrated complex properties and could show opioid-like as well as anti-opioid effects. The aim of this review is to detail the phenomenon of crosstalk taking place between opioid and anti-opioid systems at the in vivo pharmacological level and to propose a cellular and molecular basis for these interactions. A better knowledge of these mechanisms has potential therapeutic interest for the control of opioid functions, notably for alleviating pain and/or for the treatment of opioid abuse.
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Affiliation(s)
- Ewa Gibula-Tarlowska
- Department of Pharmacology and Pharmacodynamics, Medical University, 20-059 Lublin, Poland;
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4
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Sampaio-Dias IE, Silva-Reis SC, García-Mera X, Brea J, Loza MI, Alves CS, Algarra M, Rodríguez-Borges JE. Synthesis, Pharmacological, and Biological Evaluation of MIF-1 Picolinoyl Peptidomimetics as Positive Allosteric Modulators of D 2R. ACS Chem Neurosci 2019; 10:3690-3702. [PMID: 31347842 DOI: 10.1021/acschemneuro.9b00259] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
This work describes the synthesis and pharmacological evaluation of picolinoyl-based peptidomimetics of melanocyte stimulating hormone release inhibiting factor 1 (MIF-1) as dopamine modulating agents. Eight novel peptidomimetics were tested for their ability to enhance the maximal effect of tritiated N-propylapomorphine ([3H]-NPA) at dopamine D2 receptors (D2R). Methyl picolinoyl-l-valyl-l-alaninate (compound 6b) produced a statistically significant increase in the maximal [3H]-NPA response at 0.01 nM (11.9 ± 3.7%), which is close to the effect of MIF-1 in this assay at same concentration (18.3 ± 9.1%). Functional assays measuring cAMP mobilization in the presence of dopamine corroborate the activity of peptidomimetic 6b as a positive allosteric modulator (PAM) of D2R. In this assay, 6b produced a typical bell-shaped dose-response curve similar to that of the parent neuropeptide (18.3 ± 7.1% for 6b vs 15.4 ± 5.5% for MIF-1, both at 0.1 nM). Dose-response curves for dopamine in the presence of 6b show EC50 (0.33 ± 0.21 μM for 6b vs 0.17 ± 0.07 μM for MIF-1) and Emax (86.0 ± 5.4% for 6b vs 93.6 ± 4.4% for MIF-1) comparable to those of MIF-1, both at 0.01 nM. Furthermore, peptidomimetic 6b was tested for agonist activity at the human D2R and the results show that it displays no intrinsic agonism effect, endorsing its activity as a PAM of D2R. Cytotoxic and neurotoxic assays were performed for peptidomimetic 6b using HEK 293T cells and cortex neurons from 19 day old Wistar-Kyoto rat embryos, respectively, suggesting this analogue displays no toxicity effect in these assays up to 100 μM. Conformational energy minimization for 6b shows that this peptidomimetic cannot adopt the postulated type-II β-turn bioactive conformation, endorsing the possibility of an extended bioactive conformation as claimed by other researchers as a second bioactive conformation of MIF-1. Overall, the pharmacological and toxicological profile of peptidomimetic 6b together with its favorable druglike properties and structural simplicity makes it a potential lead compound for further development and optimization.
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Affiliation(s)
- Ivo E. Sampaio-Dias
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Sara C. Silva-Reis
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
| | - Xerardo García-Mera
- Department of Organic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - José Brea
- Innopharma Screening Platform, Biofarma Research Group, Centre of Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - M. Isabel Loza
- Innopharma Screening Platform, Biofarma Research Group, Centre of Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Carla S. Alves
- CQM - Centro de Química da Madeira, Universidade da Madeira, Campus Universitário
da Penteada, 9020-105 Funchal, Portugal
| | - Manuel Algarra
- CQM - Centro de Química da Madeira, Universidade da Madeira, Campus Universitário
da Penteada, 9020-105 Funchal, Portugal
| | - José E. Rodríguez-Borges
- LAQV/REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal
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5
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Oliver M, Gadais C, García-Pindado J, Teixidó M, Lensen N, Chaume G, Brigaud T. Trifluoromethylated proline analogues as efficient tools to enhance the hydrophobicity and to promote passive diffusion transport of the l-prolyl-l-leucyl glycinamide (PLG) tripeptide. RSC Adv 2018; 8:14597-14602. [PMID: 35540789 PMCID: PMC9079923 DOI: 10.1039/c8ra02511h] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 04/11/2018] [Indexed: 01/23/2023] Open
Abstract
The synthesis of four CF3-proline analogues of the PLG peptide is reported. Our results show that the incorporation of trifluoromethylated amino acids (Tfm-AAs) at the N-terminal position of a peptide significantly increases its hydrophobicity. In addition, depending on the relative configuration and the position of the CF3 group, Tfm-AAs can also promote passive diffusion transport.
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Affiliation(s)
- Martin Oliver
- Laboratoire de Chimie Biologique (LCB), Université de Cergy-Pontoise 5 mail Gay-Lussac, Neuville-sur-Oise 95031 Cergy-Pontoise France
| | - Charlène Gadais
- Laboratoire de Chimie Biologique (LCB), Université de Cergy-Pontoise 5 mail Gay-Lussac, Neuville-sur-Oise 95031 Cergy-Pontoise France
| | - Júlia García-Pindado
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST) C/ Baldiri Reixac 10 08028 Barcelona Spain
| | - Meritxell Teixidó
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona Institute of Science and Technology (BIST) C/ Baldiri Reixac 10 08028 Barcelona Spain
| | - Nathalie Lensen
- Laboratoire de Chimie Biologique (LCB), Université de Cergy-Pontoise 5 mail Gay-Lussac, Neuville-sur-Oise 95031 Cergy-Pontoise France
| | - Grégory Chaume
- Laboratoire de Chimie Biologique (LCB), Université de Cergy-Pontoise 5 mail Gay-Lussac, Neuville-sur-Oise 95031 Cergy-Pontoise France
| | - Thierry Brigaud
- Laboratoire de Chimie Biologique (LCB), Université de Cergy-Pontoise 5 mail Gay-Lussac, Neuville-sur-Oise 95031 Cergy-Pontoise France
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6
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Jlalia I, Lensen N, Chaume G, Dzhambazova E, Astasidi L, Hadjiolova R, Bocheva A, Brigaud T. Synthesis of an MIF-1 analogue containing enantiopure (S)-α-trifluoromethyl-proline and biological evaluation on nociception. Eur J Med Chem 2013; 62:122-9. [PMID: 23353749 DOI: 10.1016/j.ejmech.2012.12.041] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 12/19/2012] [Accepted: 12/23/2012] [Indexed: 11/16/2022]
Abstract
The synthesis and the effect of a novel MIF-1 analogue on nociception during acute pain in rat model are reported. The synthesis of this enantiopure trifluoromethyl group containing tripeptide was performed through a peptide coupling reaction between the HCl. Leu-Gly-NH2 and the (S)-α-Tfm-proline. The analgesic effect of the CF3-(MIF-1) 2 has been evaluated in vivo on rat model by paw pressure (PP) and hot plate (HP) tests and compared to the native peptide MIF-1. Highest analgesic effect was observed with CF3-(MIF-1) 2 only in PP test. In order to study the mechanisms of nociception induced by the studied peptides, the involvement of the opioid and the nitric oxideergic systems was investigated. The results are in favor of a participation of both system since pretreatment, 20 min before injection of the CF3-(MIF-1) 2, with the non-competitive antagonist of opiate receptors naloxone, the nitric oxide synthase (NOS) inhibitor l-N(G)-nitroarginine ester (l-NAME) or the nitric oxide (NO) donor l-arginine (l-Arg) significantly decreased the pain perception in PP and HP tests.
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Affiliation(s)
- Ibtissem Jlalia
- Laboratoire SOSCO, Université de Cergy-Pontoise, EA 4505, 5 Mail Gay Lussac, Neuville sur Oise, 95000 Cergy-Pontoise Cedex, France
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7
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Mann A, Verma V, Basu D, Skoblenick KJ, Beyaert MGR, Fisher A, Thomas N, Johnson RL, Mishra RK. Specific binding of photoaffinity-labeling peptidomimetics of Pro-Leu-Gly-NH2 to the dopamine D2L receptor: evidence for the allosteric modulation of the dopamine receptor. Eur J Pharmacol 2010; 641:96-101. [PMID: 20639138 DOI: 10.1016/j.ejphar.2010.05.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/13/2010] [Accepted: 05/17/2010] [Indexed: 11/19/2022]
Abstract
The present study was undertaken to investigate the mechanistic role of l-prolyl-l-leucyl-glycinamide (PLG) in modulating agonist binding to the dopamine D(2L) receptor. Competition and displacement assays indicate that the photoaffinity-labeling peptidomimetics of PLG, 3(R)-[(4(S)-(4-azido-2-hydroxy-benzoyl) amino-2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide hydrochloride (1a) and 3(R)-[(4(S)-(4-azido-2-hydroxy-5-iodo-benzoyl)amino-2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide hydrochloride (1b) bind at the same site as PLG. Autoradiography was used to establish the covalent binding of [(125)I]-1b to an approximately 51kDa protein in bovine striatal membranes. Western blot analysis with a dopamine D(2L)-specific antibody, in combination with autoradiography, following a two-dimensional gel separation, suggested this approximately 51kDa protein to be the dopamine D(2L) receptor. Further evidence for binding of 1b to dopamine D(2L) was provided by samples immunoprecipitated with the D(2L) antibody. These samples were analyzed by western blotting in parallel with autoradiography of [(125)I]-1b labeled protein. Both methods revealed bands at approximately 51kDa. Furthermore, PLG is shown to compete with 1b for binding to the dopamine D(2L) receptor as determined by autoradiography, as well as competition experiments with PLG and 1a. Collectively, these findings suggest the successful development of a photoaffinity-labeling agent, compound 1b, that has been used to elucidate the interaction of PLG specifically with the dopamine D(2L) receptor.
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Affiliation(s)
- Amandeep Mann
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada
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8
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Bocheva A, Dzambazova E, Hadjiolova R, Traikov L, Mincheva R, Bivolarski I. Effect of Tyr-MIF-1 peptides on blood ACTH and corticosterone concentration induced by three experimental models of stress. ACTA ACUST UNITED AC 2008; 28:117-23. [DOI: 10.1111/j.1474-8673.2008.00425.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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9
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Castellano JM, Batrynchuk J, Dolbeare K, Verma V, Mann A, Skoblenick KJ, Johnson RL, Mishra RK. MIF-1 and its peptidomimetic analogs attenuate haloperidol-induced vacuous chewing movements and modulate apomorphine-induced rotational behavior in 6-hydroxydopamine-lesioned rats. Peptides 2007; 28:2009-15. [PMID: 17766011 DOI: 10.1016/j.peptides.2007.07.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Accepted: 07/13/2007] [Indexed: 11/27/2022]
Abstract
Two melanocyte-stimulating hormone release inhibiting factor-1 (MIF-1) also known as L-prolyl-L-leucyl-glycinamide (PLG) peptidomimetic analogs, 3(R)-[[[2(S)-pyrrolidinyl]carbonyl]-amino]-3-(butyl)-2-oxo-1-pyrrolidineacetamide trifluoroacetate (A) and 3(R)-[[[2(S)-pyrrolidinyl]carbonyl]amino]-3-(benzyl)-2-oxo-1-pyrrolidineacetamide trifluoroacetate (B), were evaluated for their ability to modulate dopaminergic activity by measuring apomorphine-induced rotations in 6-hydroxydopamine (6-OHDA)-lesioned rats, and haloperidol (HP)-induced vacuous chewing movements (VCMs) in rats; animal models of Parkinson's disease (PD) and human tardive dyskinesia (TD), respectively. In the 6-OHDA model, both analogs were found to potentiate the contralateral rotational behavior induced by apomorphine dose-dependently and with approximately the same potency. Furthermore, each analog was able to significantly attenuate HP-induced VCMs with almost equal efficacy. The potency and efficacy of these analogs were significantly greater than their parent compound, PLG. These results suggest that both analogs can modulate dopaminergic activity in vivo, likely by the same mechanisms recruited by PLG previously reported.
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Affiliation(s)
- Jessica M Castellano
- Department of Psychiatry and Behavioral Neurosciences, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada L8N 3Z5
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10
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Nakayama D, Watanabe C, Watanabe H, Mizoguchi H, Sakurada T, Sakurada S. A Tyr-W-MIF-1 analog containing d-Pro2 discriminates among antinociception in mice mediated by different classes of μ-opioid receptors. Eur J Pharmacol 2007; 563:109-16. [PMID: 17343845 DOI: 10.1016/j.ejphar.2007.01.068] [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: 11/18/2006] [Revised: 01/13/2007] [Accepted: 01/23/2007] [Indexed: 11/25/2022]
Abstract
The antagonism by Tyr-D-Pro-Trp-Gly-NH2 (D-Pro2-Tyr-W-MIF-1), a Tyr-Pro-Trp-Gly-NH2 (Tyr-W-MIF-1) analog, of the antinociception induced by the mu-opioid receptor agonists Tyr-W-MIF-1, [D-Ala2,NMePhe4,Gly(ol)5]-enkephalin (DAMGO), Tyr-Pro-Trp-Phe-NH2 (endomorphin-1), and Tyr-Pro-Phe-Phe-NH2 (endomorphin-2) was studied with the mouse tail-flick test. D-Pro2-Tyr-W-MIF-1 (0.5-3 nmol) given intracerebroventricularly (i.c.v.) had no effect on the thermal nociceptive threshold. High doses of D-Pro2-Tyr-W-MIF-1 (4-16 nmol) administered i.c.v. produced antinociception with a low intrinsic activity of about 30% of the maximal possible effect. D-Pro2-Tyr-W-MIF-1 (0.25-2 nmol) co-administered i.c.v. showed a dose-dependent attenuation of the antinociception induced by Tyr-W-MIF-1 or DAMGO without affecting endomorphin-2-induced antinociception. A 0.5 nmol dose of D-Pro2-Tyr-W-MIF-1 significantly attenuated Tyr-W-MIF-1-induced antinociception but not DAMGO- or endomorphin-1-induced antinociception. The highest dose (2 nmol) of D-Pro2-Tyr-W-MIF-1 almost completely attenuated Tyr-W-MIF-1-induced antinociception. However, that dose of D-Pro2-Tyr-W-MIF-1 significantly but not completely attenuated endomorphin-1 or DAMGO-induced antinociception, whereas the antinociception induced by endomorphin-2 was still not affected by D-Pro2-Tyr-W-MIF-1. Pretreatment i.c.v. with various doses of naloxonazine, a mu1-opioid receptor antagonist, attenuated the antinociception induced by Tyr-W-MIF-1, endomorphin-1, endomorphin-2, or DAMGO. Judging from the ID50 values for naloxonazine against the antinociception induced by the mu-opioid receptor agonists, the antinociceptive effect of Tyr-W-MIF-1 is extremely less sensitive to naloxonazine than that of endomorphin-1 or DAMGO. In contrast, endomorphin-2-induced antinociception is extremely sensitive to naloxonazine. The present results clearly suggest that D-Pro2-Tyr-W-MIF-1 is a selective antagonist for the mu2-opioid receptor in the mouse brain. D-Pro2-Tyr-W-MIF-1 may also discriminate between Tyr-W-MIF-1-induced antinociception and the antinociception induced by endomorphin-1 or DAMGO, which both show a preference for the mu2-opioid receptor in the brain.
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MESH Headings
- Analgesics, Opioid/administration & dosage
- Analgesics, Opioid/pharmacology
- Analgesics, Opioid/therapeutic use
- Animals
- Brain/drug effects
- Brain/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Hot Temperature
- Injections, Intraventricular
- MSH Release-Inhibiting Hormone/administration & dosage
- MSH Release-Inhibiting Hormone/analogs & derivatives
- MSH Release-Inhibiting Hormone/pharmacology
- MSH Release-Inhibiting Hormone/therapeutic use
- Male
- Mice
- Naloxone/analogs & derivatives
- Naloxone/pharmacology
- Narcotic Antagonists/administration & dosage
- Narcotic Antagonists/pharmacology
- Narcotic Antagonists/therapeutic use
- Oligopeptides/pharmacology
- Pain/metabolism
- Pain/physiopathology
- Pain/prevention & control
- Pain Measurement
- Pain Threshold/drug effects
- Reaction Time/drug effects
- Receptors, Opioid, mu/drug effects
- Receptors, Opioid, mu/metabolism
- Somatostatin/analogs & derivatives
- Somatostatin/pharmacology
- Time Factors
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Affiliation(s)
- Daisuke Nakayama
- Department of Physiology and Anatomy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
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11
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Verma V, Mann A, Costain W, Pontoriero G, Castellano JM, Skoblenick K, Gupta SK, Pristupa Z, Niznik HB, Johnson RL, Nair VD, Mishra RK. Modulation of agonist binding to human dopamine receptor subtypes by L-prolyl-L-leucyl-glycinamide and a peptidomimetic analog. J Pharmacol Exp Ther 2005; 315:1228-36. [PMID: 16126839 DOI: 10.1124/jpet.105.091256] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was undertaken to investigate the role of the hypothalamic tripeptide L-prolyl-L-leucyl-glycinamide (PLG) and its conformationally constrained analog 3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA) in modulating agonist binding to human dopamine (DA) receptor subtypes using human neuroblastoma SH-SY5Y cells stably transfected with respective cDNAs. Both PLG and PAOPA enhanced agonist [3H]N-propylnorapomorphine (NPA) and [3H]quinpirole binding in a dose-dependent manner to the DA D2L,D2S, and D4 receptors. However, agonist binding to the D1 and D3 receptors and antagonist binding to the D2L receptors by PLG were not significantly affected. Scatchard analysis of [3H]NPA binding to membranes in the presence of PLG revealed a significant increase in affinity of the agonist binding sites for the D2L, D2S, and D4 receptors. Analysis of agonist/antagonist competition curves revealed that PLG and PAOPA increased the population and affinity of the high-affinity form of the D2L receptor and attenuated guanosine 5'-(beta,gamma-imido)-triphosphate-induced inhibition of high-affinity agonist binding sites for the DA D2L receptor. Furthermore, direct NPA binding with D2L cell membranes pretreated with suramin, a compound that can uncouple receptor/G protein complexes, and incubated with and without DA showed that both PLG and PAOPA had only increased agonist binding in membranes pretreated with both suramin and DA, suggesting that PLG requires the D2L receptor/G protein complex to increase agonist binding. These results suggest that PLG possibly modulates DA D2S, D2L, and D4 receptors in an allosteric manner and that the coupling of D2 receptors to the G protein is essential for this modulation to occur.
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Affiliation(s)
- Vaneeta Verma
- Department of Psychiatry and Behavioural Neuroscience, McMaster University, Hamilton, Ontario, Canada
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12
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Watanabe H, Nakayama D, Ito K, Watanabe C, Mizoguchi H, Fujimura T, Murayama K, Kawamura S, Sato T, Sakurada C, Sakurada T, Sakurada S. A Tyr-W-MIF-1 Analog Containing D-Pro2 Acts as a Selective μ2-Opioid Receptor Antagonist in the Mouse. J Pharmacol Exp Ther 2004; 312:1075-81. [PMID: 15561796 DOI: 10.1124/jpet.104.075697] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The antagonistic properties of Tyr-d-Pro-Trp-Gly-NH(2) (d-Pro(2)-Tyr-W-MIF-1), a Tyr-Pro-Trp-Gly-NH(2)(Tyr-W-MIF-1) analog, on the antinociception induced by the mu-opioid receptor agonists Tyr-W-MIF-1, [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO), Tyr-Pro-Trp-Phe-NH(2) (endomorphin-1), and Tyr-Pro-Phe-Phe-NH(2) (endomorphin-2) were studied in the mouse paw-withdrawal test. d-Pro(2)-Tyr-W-MIF-1 injected intrathecally (i.t.) had no apparent effect on the thermal nociceptive threshold. d-Pro(2)-Tyr-W-MIF-1 (0.1-0.4 nmol) coadministered i.t. showed a dose-dependent attenuation of the antinociception induced by Tyr-W-MIF-1 without affecting endomorphin- or DAMGO-induced antinociception. However, higher doses of d-Pro(2)-Tyr-W-MIF-1 (0.8-1.2 nmol) significantly attenuated endomorphin-1- or DAMGO-induced antinociception, whereas the antinociception induced by endomorphin-2 was still not affected by d-Pro(2)-Tyr-W-MIF-1. Pretreatment i.t. with various doses of naloxonazine, a mu(1)-opioid receptor antagonist, attenuated the antinociception induced by Tyr-W-MIF-1, endomorphin-1, endomorphin-2, or DAMGO. Judging from the ID(50) values for naloxonazine against the antinociception induced by the mu-opioid receptor agonists, the antinociceptive effect of Tyr-W-MIF-1 is extremely less sensitive to naloxonazine than those of endomorphin-1 or DAMGO. In contrast, endomorphin-2-induced antinociception is extremely sensitive to naloxonazine. The present results clearly suggest that d-Pro(2)-Tyr-W-MIF-1 is the selective antagonist to be identified for the mu(2)-opioid receptor in the mouse spinal cord. d-Pro(2)-Tyr-W-MIF-1 may also discriminate between Tyr-W-MIF-1-induced antinociception and the antinociception induced by endomorphin-1 or DAMGO, all of which show a preference for the mu(2)-opioid receptor in the spinal cord.
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Affiliation(s)
- Hiroyuki Watanabe
- Department of Physiology and Anatomy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
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13
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Goodman CB, Heyliger S, Emilien B, Partilla JS, Yang HY, Lee CH, Cadet JL, Rothman RB. Chronic exposure to antibodies directed against anti-opiate peptides alter delta-opioid receptor levels. Peptides 1999; 20:1419-24. [PMID: 10698116 DOI: 10.1016/s0196-9781(99)00151-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The development of addictive states in response to chronic opioid use may be regulated partially by the release of endogenous peptides. These anti-opiate peptides (AOP) are secreted or released into the CNS and produce diverse actions that counterbalance the effects of prolonged opiate exposure. Though the mechanism(s) by which these peptides exert their physiological properties remain largely unknown, there is some indication that AOP's modulate opioid receptor levels. In this study, we investigated the effects of chronically infused alpha-melanocyte stimulating hormone (alpha-MSH), dynorphin(1-8) (DYN(1-8)), dynorphin A (DYNA), and NPFF antibodies on delta-opioid receptor expression in rat brains. Quantitative autoradiographic experiments revealed that antibodies directed against alpha-MSH and DYNA produced significant increases in delta receptor levels in the caudate, claustrum, and cingulate cortex of the rat brain. Conversely, NPFF monoclonal antibodies caused significant decreases in the caudate, nucleus accumbens, olfactory tubercle, and cingulate cortex. These results suggest that the density of delta-opioid receptors is affected by changes in the levels of the anti-opioid peptides in the extracelluar fluid in the rat brain.
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Affiliation(s)
- C B Goodman
- Florida A&M University, College of Pharmacy and Pharmaceutical Sciences, Tallahassee, FL 32303, USA.
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14
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d'Amore A, Loizzo A. Effects of neonatal treatment with Tyr-MIF-1 and naloxone on the long-term body weight gain induced by repeated postnatal stressful stimuli. Peptides 1999; 20:1425-30. [PMID: 10698117 DOI: 10.1016/s0196-9781(99)00152-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Stressful stimuli repeatedly applied during the first postnatal weeks can induce body weight gain in the mouse during adulthood. This effect can be prevented by injecting naloxone concomitantly with stress. The peptides belonging to the Tyr-MIF-1 family have a great modulating activity on numerous stress-induced phenomena. The aim of the present work was to compare the effect of repeated neonatal injections of Tyr-MIF-1 or naloxone on the long-term body weight gain induced by a stressing procedure applied daily during the first three weeks of life. The results indicate that although naloxone blocked the development of the stress-induced effects, Tyr-MIF-1 potentiated them.
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Affiliation(s)
- A d'Amore
- Laboratorio di Alimenti, Istituto Superiore di Sanità, Rome, Italy.
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15
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Bell RL, Vaccarino AL, Olson RD, Olson GA, Nores WL, Cambre JG, Zadina JE, Kastin AJ. Tolerance and morphine-induced cross-tolerance are not shown to Tyr-W-MIF-1 analgesia. Peptides 1999; 20:971-8. [PMID: 10503776 DOI: 10.1016/s0196-9781(99)00090-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Tolerance and cross-tolerance between Tyr-W-MIF-1, a mixed micro-agonist/antagonist, and morphine were examined. Opiate dependence also was examined. Rats were pretreated with Tyr-W-MIF-1, morphine, or saline for 4 days. On day 5, the animals were tested for Tyr-W-MIF-1 analgesia, morphine analgesia, or naloxone-precipitated withdrawal. Tyr-W-MIF-1- and morphine-pretreated animals showed similar levels of dependence. Animals pretreated with Tyr-W-MIF-1 failed to express tolerance to Tyr-W-MIF-1 analgesia but did display cross-tolerance to morphine analgesia. Animals pretreated with morphine displayed tolerance to morphine analgesia but did not express cross-tolerance to Tyr-W-MIF-1 analgesia. Therefore, tolerance and morphine-induced cross-tolerance were not expressed to Tyr-W-MIF-1 analgesia.
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Affiliation(s)
- R L Bell
- Department of Psychology, University of New Orleans, LA 70148, USA.
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16
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Costain WJ, Buckley AT, Evans MC, Mishra RK, Johnson RL. Modulatory effects of PLG and its peptidomimetics on haloperidol-induced catalepsy in rats. Peptides 1999; 20:761-7. [PMID: 10477133 DOI: 10.1016/s0196-9781(99)00060-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A behavioral model of dopaminergic function in the rat was used to examine the anticataleptic effects of L-prolyl-L-leucyl-glycinamide (PLG) and peptidomimetic analogs of PLG. Administration of 1 mg/kg PLG intraperitoneally significantly attenuated haloperidol (1 mg/kg)-induced catalepsy (as measured by the standard horizontal bar test), whereas doses of 0.1 and 10 mg/kg PLG did not. Eight synthetic PLG peptidomimetics (Calpha, alpha-dialkylated glycyl residues with lactam bridge constraint [1-4] and without [5-8]) were tested in the same manner (at a dose of 1 microg/kg) and categorized according to their activity, i.e. very active (5), moderately active (2, 3, 4, and 6), and inactive (1, 7, and 8). The catalepsy-reversal action of the diethylglycine-substituted peptidomimetic 5 was examined further and found to exhibit a U-shaped dose-response effect with an optimal dose of 1 microg/kg. The similarity between the effects of PLG and the synthetic peptidomimetics suggests a common mechanism of action. Finally, the synthetic peptidomimetics examined here, particularly peptidomimetic 5, were more effective than PLG in attenuating haloperidol-induced catalepsy.
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Affiliation(s)
- W J Costain
- Department of Psychiatry and Behavioural Neuroscience, McMaster University, Hamilton, Ontario, Canada
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17
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Marcotte ER, Chugh A, Mishra RK, Johnson RL. Protection against MPTP treatment by an analog of Pro-Leu-Gly-NH2 (PLG, MIF-1). Peptides 1998; 19:403-6. [PMID: 9493876 DOI: 10.1016/s0196-9781(97)00321-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
3(R)-[(2(S)-Pyrrolidinyl-carbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA) is a peptidomimetic analog of Pro-Leu-Gly-NH2 (PLG or MIF-1) that has previously been demonstrated to be more potent and efficacious that MIF-1 in enhancing dopamine receptor activity. Given the ability of MIF-1 to protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioning in C57 BL/6 mice, the present study was undertaken to evaluate the neuroprotective effect of PAOPA in this model. PAOPA was found to be more potent and efficacious that MIF-1 in sparing dopamine and its metabolite levels following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration. Whether the enhanced neuroprotective effect of PAOPA is due to dopamine receptor stimulation, or a result of reduced oxidative stress through normalization of dopamine turnover, remains to be determined.
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Affiliation(s)
- E R Marcotte
- Department of Psychiatry, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
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18
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Cucumel K, Bagnol D, Moinier D, Fischer J, Conrath M, Cupo A. The rat dermorphin-like immunoreactivity is supported by an aminopeptidase resistant peptide. J Neuroimmunol 1998; 81:211-24. [PMID: 9521624 DOI: 10.1016/s0165-5728(97)00182-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Site-directed antibodies against synthetic related dermorphin peptides were previously produced and characterized. One of them, which specifically recognizes the crucial 'opioid message' (the N-terminal part of the dermorphin molecule (i.e. Tyr-D-Ala-Phe-Gly) was selected in order to detect and locate endogenous dermorphin-like molecules in rat, mouse and guinea pig tissues. Dermorphin-like peptides were found to be present in tissues known to contain peptides such as neurons in the central nervous system, nerve fibers in the gut and B and T immune cells. With all the tissues assayed, the HPLC profile obtained on the immunoreactive material showed the same main peak eluted at a retention time of 32 +/- 1 min. The results of biochemical experiments in which enzymatic treatments were performed on the dermorphin-like immunoreactivity indicate the immunoreactivity is a peptide resistant to aminopeptidase hydrolysis. This finding suggests the presence of a residue conferring resistance to proteolytic processes of this kind, which is likely to be a D-amino acid residue.
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Affiliation(s)
- K Cucumel
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS-UPR411, Valbonne, France
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19
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Gergen KA, Zadina JE, Kastin AJ, Paul D. Intrathecal Tyr-W-MIF-1 produces potent, naloxone-reversible analgesia modulated by alpha 2-adrenoceptors. Eur J Pharmacol 1996; 298:235-9. [PMID: 8846821 DOI: 10.1016/0014-2999(95)00823-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Spinal administration of morphine or [D-Ala2,MePhe4,Gly(ol)5)]enkephalin (DAMGO) produces potent, naloxone-reversible analgesia that is modulated by alpha 2-adrenoceptors. Tyr-W-MIF-1 (Tyr-Pro-Trp-Gly-NH2) is a naturally occurring, amidated tetrapeptide that is structurally related to the melanocyte-stimulating hormone release inhibiting factor-1 (MIF-1) family of endogenous peptides. Tyr-W-MIF-1 displays high selectivity for the mu-opioid receptor. We investigated the effect of spinal administration of Tyr-W-MIF-1 on analgesia using the mouse tail-flick assay. Intrathecal (i.t.) administration of Tyr-W-MIF-1 produced a dose-dependent analgesic response, with an ED50 of 0.41 microgram, that was reversed by naloxone. Pretreatment with the mu-opioid receptor-selective antagonist beta-funaltrexamine blocked the effect of i.t. Tyr-W-MIF-1. However, pretreatment with the mu1-opioid receptor-selective antagonist naloxonazine did not antagonize the analgesia, indicating the effect was mediated through spinal mu2-opioid receptors. Pretreatment with desipramine, an inhibitor of norepinephrine reuptake, potentiated the analgesic effect of i.t. Tyr-W-MIF-1, producing a 3.1-fold leftward shift in the dose-response curve. Spinal administration of yohimbine, an alpha 2-adrenoceptor-selective antagonist, significantly attenuated the analgesic effect of Tyr-W-MIF-1. Thus, the potent analgesic effect of i.t. Tyr-W-MIF-1 is mediated through spinal mu2-receptors, and is modulated by norepinephrine and alpha 2-adrenoceptors.
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20
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Abstract
The numerous endogenous opioid peptides (beta-endorphin, enkephalins, dynorphins ... ) and the exogenous opioids (such as morphine) exert their effects through the activation of receptors belonging to four main types, mu, delta, kappa and epsilon. Opioidergic neurones and opioid receptors are largely distributed centrally and peripherally. It is thus not surprising that opioids have numerous pharmacological effects and that endogenous opioids are thought to be involved in the physiological control of various functions, among which nociception is particularly emphasized. Some opioid targets may be components of homeostatic systems tending to reduce the effects of opioids. "Anti-opioid" properties have been attributed to various peptides, especially cholecystokinin (CCK), neuropeptide FF (NPFF) and melanocyte inhibiting factor (MIF)-related peptides. In addition, a particular place should be attributed, paradoxically, to opioid peptides themselves among the anti-opioid peptides. These peptides can oppose some of the acute effects of opioids, and a hyperactivation of anti-opioid peptidergic neurones due to the chronic administration of opioids may be involved in the development of opioid tolerance and/or dependence. In fact, CCK, NPFF and the MIF family of peptides have complex properties and can act as opioid-like as well as anti-opioid peptides. Thus, "opioid modulating peptides" would be a better term to designate these peptides, which probably participate, together with the opioid systems, in multiple feed-back loops for the maintenance of homeostasis. "Opioid modulating peptides" have generally been shown to act through the activation of their own receptors. For example, CCK appears to exert its anti-opioid actions mainly through the activation of CCK-B receptors, whereas its opioid-like effects seem to result from the stimulation of CCK-A receptors. However, the partial agonistic properties at opioid receptors of some MIF-related peptides very likely contribute to their ability to modulate the effects of opioids. CCK- and NPFF-related drugs have potential therapeutic interest as adjuncts to opioids for alleviating pain and/or for the treatment of opioid abuse.
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