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Abstract
The field of peptides exploded in the 1970's and has continued to be a major area of discovery. Among the early discoveries was that peptides administered peripherally could affect brain functions. This led Kastin to propose that peptides could cross the blood-brain barrier (BBB). Although initially very controversial, Kastin, I, and others demonstrated not only that peptides can cross the BBB, but elucidated many fundamental characteristics of that passage. That work was in large part the basis of the 2022 Viktor Mutt Lectureship. Here, we review some of the early work with current updates on topics related to the penetration of peptides across the BBB. We briefly review mechanisms by which peripherally administered peptides can affect brain function without crossing the BBB, and then review the major mechanisms by which peptides and their analogs have been show to cross the BBB: transmembrane diffusion, saturable transport, and adsorptive transcytosis. Saturable transport systems are adaptable to physiologic changes and can be altered by disease states. In particular, the transport across the BBB of insulin and of pituitary adenylate cyclase activating polypeptide (PACAP) illustrate many of the concepts regarding peptide transport across the BBB.
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Affiliation(s)
- William A Banks
- Geriatric Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care System, Seattle 98108, WA, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98104, USA
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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: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
In commemoration of Abba J. Kastin's exceptional service as the founding editor for the international journal Peptides, I review our collaborative work on how neuropeptides are involved in depression and other neuropsychiatric behavior. A special focus is on MIF-1 (prolyl-leucyl-glycinamide) that was discovered in the Kastin laboratory and shown effective to treat human depression with greater efficacy and faster onset of action than traditional antidepressants at the time of clinical trial. My personal reflection of the evolving changes of translational research on neuropeptides will hopefully provide some insight to young investigators.
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Abstract
In this Festschrift, I discuss the career and guiding principles to which Abba J. Kastin has adhered during the last 20 years we worked together. I briefly describe the history of our joint laboratory group, the context of studies of peptide permeation across the blood-brain barrier (BBB), and newer developments in the BBB Group as Abba steps down after serving 35 years as the founding Editor-in-Chief for Peptides. Abba's BBB studies on peptides have contributed to concepts in the neuroendocrinology of feeding and developed information on molecular trafficking across BBB cells. The astroglial leptin signaling studies and the interactions of sleep and BBB are two major directions, whereas the long-term MIF-1 project demarcates a tortuous road on translational research.
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Affiliation(s)
- Weihong Pan
- Biopotentials Sleep Center, Baton Rouge, LA 70809, USA.
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