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St. Onge C, Pagare PP, Zheng Y, Arriaga M, Stevens DL, Mendez RE, Poklis JL, Halquist MS, Selley DE, Dewey WL, Banks ML, Zhang Y. Systematic Structure-Activity Relationship Study of Nalfurafine Analogues toward Development of Potentially Nonaddictive Pain Management Treatments. J Med Chem 2024; 67:9552-9574. [PMID: 38814086 PMCID: PMC11181328 DOI: 10.1021/acs.jmedchem.4c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/08/2024] [Accepted: 05/22/2024] [Indexed: 05/31/2024]
Abstract
Despite the availability of numerous pain medications, the current array of Food and Drug Administration-approved options falls short in adequately addressing pain states for numerous patients and consequently worsens the opioid crisis. Thus, it is imperative for basic research to develop novel and nonaddictive pain medications. Toward addressing this clinical goal, nalfurafine (NLF) was chosen as a lead and its structure-activity relationship (SAR) systematically studied through design, syntheses, and in vivo characterization of 24 analogues. Two analogues, 21 and 23, showed longer durations of action than NLF in a warm-water tail immersion assay, produced in vivo effects primarily mediated by KOR and DOR, penetrated the blood-brain barrier, and did not function as reinforcers. Additionally, 21 produced fewer sedative effects than NLF. Taken together, these results aid the understanding of NLF SAR and provide insights for future endeavors in developing novel nonaddictive therapeutics to treat pain.
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Affiliation(s)
- Celsey
M. St. Onge
- Department
of Medicinal Chemistry, Virginia Commonwealth
University, 800 E. Leigh
Street, Richmond, Virginia 23219, United States
| | - Piyusha P. Pagare
- Department
of Medicinal Chemistry, Virginia Commonwealth
University, 800 E. Leigh
Street, Richmond, Virginia 23219, United States
| | - Yi Zheng
- Department
of Medicinal Chemistry, Virginia Commonwealth
University, 800 E. Leigh
Street, Richmond, Virginia 23219, United States
| | - Michelle Arriaga
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - David L. Stevens
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - Rolando E. Mendez
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - Justin L. Poklis
- Department
of Pharmaceutics, Virginia Commonwealth
University, 410 North
12th Street, Richmond, Virginia 23298, United States
| | - Matthew S. Halquist
- Department
of Pharmaceutics, Virginia Commonwealth
University, 410 North
12th Street, Richmond, Virginia 23298, United States
| | - Dana E. Selley
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - William L. Dewey
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - Matthew L. Banks
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
| | - Yan Zhang
- Department
of Medicinal Chemistry, Virginia Commonwealth
University, 800 E. Leigh
Street, Richmond, Virginia 23219, United States
- Department
of Pharmacology and Toxicology, Virginia
Commonwealth University, 410 North 12th Street, Richmond, Virginia 23298, United States
- Institute
for Drug and Alcohol Studies, 203 East Cary Street, Richmond, Virginia 23298, United States
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2
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Huang P, Ho CK, Cao D, Inan S, Rawls SM, Li M, Huang B, Pagare PP, Townsend EA, Poklis JL, Halquist MS, Banks M, Zhang Y, Liu-Chen LY. NCP, a dual kappa and mu opioid receptor agonist, is a potent analgesic against inflammatory pain without reinforcing or aversive properties. J Pharmacol Exp Ther 2024; 389:JPET-AR-2023-001870. [PMID: 38409113 PMCID: PMC10949162 DOI: 10.1124/jpet.123.001870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 01/24/2024] [Accepted: 01/30/2024] [Indexed: 02/28/2024] Open
Abstract
While agonists of mu (MOR) and kappa (KOR) opioid receptors have analgesic effects, they produce euphoria and dysphoria, respectively. Other side effects include respiratory depression and addiction for MOR agonists and sedation for KOR agonists. We reported that 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-{[4'-(2'-cyanopyridyl)]carboxamido}cmorphinan (NCP) displayed potent KOR full agonist and MOR partial agonist activities (58%) with 6.5x KOR-over-MOR selectivity in vitro Herein, we characterized pharmacological effects of NCP in rodents. In mice, NCP exerted analgesic effects against inflammatory pain in both the formalin test and the acetic acid writhing test, with A50 values of 47.6 and 14.4 microg/kg (s.c.), respectively. The analgesic effects in the acetic acid writhing test were mediated by the KOR. NCP at doses much higher than those effective in reducing inflammatory pain did not produce antinociception in the hot plate and tail flick tests, inhibit compound 48/80-induced scratching, cause conditioned place aversion (CPA) or preference, impair rotarod performance, inhibit locomotor activity, cause respiratory depression, or precipitate morphine withdrawal. However, NCP (10~100 microg/kg) inhibited gastrointestinal transit with a maximum of ~40% inhibition. In MOR knockout mice, NCP caused CPA, demonstrating that its lack of CPA is due to combined actions on the MOR and KOR. Following s.c. injection, NCP penetrated into the mouse brain. In rats trained to self-administer heroin, NCP (1~320 microg/kg/infusion) did not function as a reinforcer. Thus, NCP produces potent analgesic effects via KOR without side effects except constipation. Therefore, dual full KOR/partial MOR agonists with moderate KOR-over-MOR selectivity may be promising as non-addictive analgesics for inflammatory pain. Significance Statement Developing non-addictive analgesics is crucial for reducing opioid overdose deaths, minimizing drug misuse, and promoting safer pain management practices. Herein, pharmacology of a potential non-addictive analgesic, NCP, is reported. NCP has full KOR agonist / partial MOR agonist activities with a 6.5 x selectivity for KOR over MOR. Unlike MOR agonists, analgesic doses of NCP do not lead to self-administration or respiratory depression. Furthermore, NCP does not produce aversion, hypolocomotion, or motor incoordination, side effects typically associated with KOR activation.
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Affiliation(s)
- Peng Huang
- Temple University Lewis Katz School of Medicine, United States
| | - Conrad K Ho
- Temple University Lewis Katz School of Medicine, United States
| | - Danni Cao
- Temple University Lewis Katz School of Medicine, United States
| | - Saadet Inan
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Lewis Katz School of Medicine, Temple University, United States
| | - Scott M Rawls
- Temple University Lewis Katz School of Medicine, United States
| | - Mengchu Li
- Virginia Commonwealth University School of Pharmacy, United States
| | - Boshi Huang
- Virginia Commonwealth University School of Pharmacy, United States
| | - Piyusha P Pagare
- Virginia Commonwealth University School of Pharmacy, United States
| | | | | | | | - Matthew Banks
- Virginia Commonwealth University School of Medicine, United States
| | - Yan Zhang
- Virginia Commonwealth University School of Pharmacy, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, United States
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3
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Schrader TO, Lorrain KI, Bagnol D, Edu GC, Broadhead A, Baccei C, Poon MM, Stebbins KJ, Xiong Y, Lorenzana AO, Chan JR, Green AJ, Lorrain DS, Chen A. Identification and In Vivo Evaluation of Myelination Agent PIPE-3297, a Selective Kappa Opioid Receptor Agonist Devoid of β-Arrestin-2 Recruitment Efficacy. ACS Chem Neurosci 2024; 15:685-698. [PMID: 38265210 DOI: 10.1021/acschemneuro.3c00807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024] Open
Abstract
Structure-activity relationship studies led to the discovery of PIPE-3297, a fully efficacious and selective kappa opioid receptor (KOR) agonist. PIPE-3297, a potent activator of G-protein signaling (GTPγS EC50 = 1.1 nM, 91% Emax), did not elicit a β-arrestin-2 recruitment functional response (Emax < 10%). Receptor occupancy experiments performed with the novel KOR radiotracer [3H]-PIPE-3113 revealed that subcutaneous (s.c.) administration of PIPE-3297 at 30 mg/kg in mice achieved 90% occupancy of the KOR in the CNS 1 h post dose. A single subcutaneous dose of PIPE-3297 in healthy mice produced a statistically significant increase of mature oligodendrocytes (P < 0.0001) in the KOR-enriched striatum, an effect that was not observed in animals predosed with the selective KOR antagonist norbinaltorphimine. An equivalent dose given to mice in an open-field activity-monitoring system revealed a small KOR-independent decrease in total locomotor activity versus vehicle measured between 60 and 75 min post dose. Daily doses of PIPE-3297 at both 3 and 30 mg/kg s.c. reduced the disease score in the mouse experimental autoimmune encephalomyelitis (EAE) model. Visually evoked potential (VEP) N1 latencies were also significantly improved versus vehicle in both dose groups, and latencies matched those of untreated animals. Taken together, these findings highlight the potential therapeutic value of functionally selective G-protein KOR agonists in demyelinating disease, which may avoid the sedating side effects typically associated with classical nonbiased KOR agonists.
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Affiliation(s)
- Thomas O Schrader
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Kym I Lorrain
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Didier Bagnol
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Geraldine C Edu
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Alexander Broadhead
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Christopher Baccei
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Michael M Poon
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Karin J Stebbins
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Yifeng Xiong
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Ariana O Lorenzana
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Jonah R Chan
- Department of Neurology, University of California, San Francisco, San Francisco, California 94143, United States
| | - Ari J Green
- Department of Neurology, University of California, San Francisco, San Francisco, California 94143, United States
| | - Daniel S Lorrain
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
| | - Austin Chen
- Contineum Therapeutics, Suite 200, 10578 Science Center Drive, San Diego, California 92121, United States
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4
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Zamarripa CA, Huskinson SL, Townsend EA, Prisinzano TE, Blough BE, Rowlett JK, Freeman KB. Contingent administration of typical and biased kappa opioid agonists reduces cocaine and oxycodone choice in a drug vs. food choice procedure in male rhesus monkeys. Psychopharmacology (Berl) 2024; 241:305-314. [PMID: 37870564 DOI: 10.1007/s00213-023-06486-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 10/10/2023] [Indexed: 10/24/2023]
Abstract
RATIONALE Combinations of mu and kappa-opioid receptor (KOR) agonists have been proposed as analgesic formulations with reduced abuse potential. The feasibility of this approach has been increased by the development of KOR agonists with biased signaling profiles that produce KOR-typical antinociception with fewer KOR-typical side effects. OBJECTIVE The present study determined if the biased KOR agonists, nalfurafine and triazole 1.1, could reduce choice for oxycodone in rhesus monkeys as effectively as the typical KOR agonist, salvinorin A. METHODS Adult male rhesus monkeys (N = 5) responded under a concurrent schedule of food delivery and intravenous cocaine injections (0.018 mg/kg/injection). Once trained, cocaine (0.018 mg/kg/injection) or oxycodone (0.0056 mg/kg/injection) was tested alone or in combination with contingent injections of salvinorin A (0.1-3.2 µg/kg/injection), nalfurafine (0.0032-0.1 µg/kg/injection), triazole 1.1 (3.2-100.0 µg/kg/injection), or vehicle. In each condition, the cocaine or oxycodone dose, as well as the food amount, was held constant across choice components, while the dose of the KOR agonist was increased across choice components. RESULTS Cocaine and oxycodone were chosen over food on more than 80% of trials when administered alone or contingently with vehicle. When KOR agonists were administered contingently with either cocaine or oxycodone, drug choice decreased in a dose-dependent manner. Salvinorin A and triazole 1.1 decreased drug-reinforcer choice without altering total trials completed (i.e., choice allocation shifted to food), while nalfurafine dose dependently decreased total trials completed. CONCLUSIONS These results demonstrate that salvinorin A and triazole 1.1, but not nalfurafine, selectively reduce cocaine and oxycodone self-administration independent of nonspecific effects on behavior, suggesting that G-protein bias does not appear to be a moderating factor in this outcome. Triazole 1.1 represents an important prototypical compound for developing novel KOR agonists as deterrents for prescription opioid abuse.
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Affiliation(s)
- C Austin Zamarripa
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - Sally L Huskinson
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
- Center for Innovation and Discovery in Addictions, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - E Andrew Townsend
- Division of Therapeutics and Medical Consequences, National Institute on Drug Abuse, North Bethesda, MD, 20852, USA
| | - Thomas E Prisinzano
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, 40536, USA
| | | | - James K Rowlett
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
- Center for Innovation and Discovery in Addictions, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - Kevin B Freeman
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA.
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA.
- Center for Innovation and Discovery in Addictions, University of Mississippi Medical Center, Jackson, MS, 39216, USA.
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5
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Ide S, Hirai T, Muto T, Yamakawa T, Ikeda K. Effects of the novel selective κ-opioid receptor agonist NP-5497-KA on morphine-induced reward-related behaviors. Sci Rep 2023; 13:18164. [PMID: 37875567 PMCID: PMC10598265 DOI: 10.1038/s41598-023-45584-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/21/2023] [Indexed: 10/26/2023] Open
Abstract
Opioid addiction and the opioid overdose epidemic are becoming more serious, and the development of therapeutic agents is essential for the pharmacological treatment of substance use disorders. The κ-opioid receptor (KOP) is a member of the opioid receptor system that has been gaining attention as a promising molecular target for the treatment of numerous human disorders, including pain, depression, anxiety, and drug addiction. Here, we biologically and pharmacologically evaluated a novel azepane-derived ligand, NP-5497-KA, as a selective KOP agonist. NP-5497-KA had 1000-fold higher selectivity for the KOP over the μ-opioid receptor (MOP), which was higher than nalfurafine (KOP/MOP: 65-fold), and acted as a selective KOP full agonist in the 3',5'-cyclic adenosine monophosphate assay. The oral administration of NP-5497-KA (1-10 mg/kg) dose-dependently suppressed morphine-induced conditioned place preference in C57BL/6 J mice, and its effects were comparable to an intraperitoneal injection of nalfurafine (1-10 μg/kg). Nalfurafine (10 μg/kg) significantly inhibited rotarod performance, whereas NP-5497-KA (10 mg/kg) exerted no effect on rotarod performance. These results indicate that NP-5497-KA may be a novel option for the treatment of opioid use disorder with fewer side effects.
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Affiliation(s)
- Soichiro Ide
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.
| | - Toshitake Hirai
- Discovery Research Laboratories, Nippon Chemiphar Co., Ltd., 1-22 Hikokawado, Misato, Saitama, 341-0005, Japan
| | - Takafumi Muto
- Discovery Research Laboratories, Nippon Chemiphar Co., Ltd., 1-22 Hikokawado, Misato, Saitama, 341-0005, Japan
| | - Tomio Yamakawa
- Discovery Research Laboratories, Nippon Chemiphar Co., Ltd., 1-22 Hikokawado, Misato, Saitama, 341-0005, Japan
| | - Kazutaka Ikeda
- Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
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6
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Cao DN, Li F, Wu N, Li J. Insights into the mechanisms underlying opioid use disorder and potential treatment strategies. Br J Pharmacol 2023; 180:862-878. [PMID: 34128238 DOI: 10.1111/bph.15592] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 12/19/2022] Open
Abstract
Opioid use disorder is a worldwide societal problem and public health burden. Strategies for treating opioid use disorder can be divided into those that target the opioid receptor system and those that target non-opioid receptor systems, including the dopamine and glutamate receptor systems. Currently, the clinical drugs used to treat opioid use disorder include the opioid receptor agonists methadone and buprenorphine, which are limited by their abuse liability, and the opioid receptor antagonist naltrexone, which is limited by poor compliance. Therefore, the development of effective medications with lower abuse liability and better potential for compliance is urgently needed. Based on recent advances in the understanding of the neurobiological mechanisms underlying opioid use disorder, potential treatment strategies and targets have emerged. This review focuses on the progress made in identifying potential targets and developing medications to treat opioid use disorder, including progress made by our laboratory, and provides insights for future medication development. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.
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Affiliation(s)
- Dan-Ni Cao
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Fei Li
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Ning Wu
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
| | - Jin Li
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China
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7
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Liu-Chen LY, Huang P. Signaling underlying kappa opioid receptor-mediated behaviors in rodents. Front Neurosci 2022; 16:964724. [PMID: 36408401 PMCID: PMC9670127 DOI: 10.3389/fnins.2022.964724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/08/2022] [Indexed: 11/06/2022] Open
Abstract
Kappa opioid receptor (KOR) agonists are potentially useful as analgesic and anti-pruritic agents, for prevention and treatment of substance use disorders, and for treatment of demyelinating diseases. However, side effects of KOR agonists, including psychotomimesis, dysphoria, and sedation, have caused early termination of clinical trials. Understanding the signaling mechanisms underlying the beneficial therapeutic effects and the adverse side effects may help in the development of KOR agonist compounds. In this review, we summarize the current knowledge in this regard in five sections. First, studies conducted on mutant mouse lines (GRK3-/-, p38alpha MAPK-/-, β-arrestin2-/-, phosphorylation-deficient KOR) are summarized. In addition, the abilities of four distinct KOR agonists, which have analgesic and anti-pruritic effects with different side effect profiles, to cause KOR phosphorylation are discussed. Second, investigations on the KOR agonist nalfurafine, both in vitro and in vivo are reviewed. Nalfurafine was the first KOR full agonist approved for clinical use and in the therapeutic dose range it did not produce significant side effects associated with typical KOR agonists. Third, large-scale high-throughput phosphoproteomic studies without a priori hypotheses are described. These studies have revealed that KOR-mediated side effects are associated with many signaling pathways. Fourth, several novel G protein-biased KOR agonists that have been characterized for in vitro biochemical properties and agonist biases and in vivo behavior effects are described. Lastly, possible mechanisms underlying KOR-mediated CPA, hypolocomotion and motor incoordination are discussed. Overall, it is agreed upon that the analgesic and anti-pruritic effects of KOR agonists are mediated via G protein signaling. However, there is no consensus on the mechanisms underlying their side effects. GRK3, p38 MAPK, β-arrestin2, mTOR pathway, CB1 cannabinoid receptor and protein kinase C have been implicated in one side effect or another. For drug discovery, after initial in vitro characterization, in vivo pharmacological characterizations in various behavior tests are still the most crucial steps and dose separation between beneficial therapeutic effects and adverse side effects are the critical determinant for the compounds to be moved forward for clinical development.
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Affiliation(s)
- Lee-Yuan Liu-Chen
- Center for Substance Abuse Research, Department of Neural Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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8
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Khan MIH, Sawyer BJ, Akins NS, Le HV. A systematic review on the kappa opioid receptor and its ligands: New directions for the treatment of pain, anxiety, depression, and drug abuse. Eur J Med Chem 2022; 243:114785. [PMID: 36179400 DOI: 10.1016/j.ejmech.2022.114785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 09/16/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022]
Abstract
Kappa opioid receptor (KOR) is a member of the opioid receptor system, the G protein-coupled receptors that are expressed throughout the peripheral and central nervous systems and play crucial roles in the modulation of antinociception and a variety of behavioral states like anxiety, depression, and drug abuse. KOR agonists are known to produce potent analgesic effects and have been used clinically for the treatment of pain, while KOR antagonists have shown efficacy in the treatment of anxiety and depression. This review summarizes the history, design strategy, discovery, and development of KOR ligands. KOR agonists are classified as non-biased, G protein-biased, and β-arrestin recruitment-biased, according to their degrees of bias. The mechanisms and associated effects of the G protein signaling pathway and β-arrestin recruitment signaling pathway are also discussed. Meanwhile, KOR antagonists are classified as long-acting and short-acting, based on their half-lives. In addition, we have special sections for mixed KOR agonists and selective peripheral KOR agonists. The mechanisms of action and pharmacokinetic, pharmacodynamic, and behavioral studies for each of these categories are also discussed in this review.
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Affiliation(s)
- Md Imdadul H Khan
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Benjamin J Sawyer
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Nicholas S Akins
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
| | - Hoang V Le
- Department of BioMolecular Sciences and Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS, 38677, USA.
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9
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Paul B, Sribhashyam S, Majumdar S. Opioid signaling and design of analgesics. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 195:153-176. [PMID: 36707153 PMCID: PMC10325139 DOI: 10.1016/bs.pmbts.2022.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Clinical treatment of acute to severe pain relies on the use of opioids. While their potency is significant, there are considerable side effects that can negatively affect patients. Their rise in usage has correlated with the current opioid epidemic in the United States, which has led to more than 70,000 deaths per year (Volkow and Blanco, 2021). Opioid-related drug development aims to make target compounds that show strong potency but with diminished side effects. Research into pharmaceuticals that could act as potential alternatives to current pains medications has relied on mechanistic insights of opioid receptors, a class of G-protein coupled receptors (GPCRs), and biased agonism, a common phenomenon among pharmaceutical compounds where downstream effects can be altered at the same receptor via different agonists. Opioids function typically by binding to an active site on the extracellular portion of opioid receptors. Once activated, the opioid receptor initiates a G-protein signaling pathway and/or the β-arrestin2 pathway. The proposed concept for the development of safe analgesics around mu and kappa opioid receptor subtypes has focused on not recruiting β-arrestin2 (biased agonism) and/or having low efficacy at the receptor (partial agonism). By altering chemical motifs on a common scaffold, chemists can take advantage of biased agonism as well as create compounds with low intrinsic efficacy for the desired treatments. This review will focus on ligands with bias profile, signaling aspects of the receptor and probe into the structural basis of receptor that leads to bias and/or partial agonism.
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Affiliation(s)
- Barnali Paul
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St Louis and Washington University School of Medicine, St Louis, MO, United States
| | - Sashrik Sribhashyam
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St Louis and Washington University School of Medicine, St Louis, MO, United States
| | - Susruta Majumdar
- Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St Louis and Washington University School of Medicine, St Louis, MO, United States.
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10
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Dalefield ML, Scouller B, Bibi R, Kivell BM. The Kappa Opioid Receptor: A Promising Therapeutic Target for Multiple Pathologies. Front Pharmacol 2022; 13:837671. [PMID: 35795569 PMCID: PMC9251383 DOI: 10.3389/fphar.2022.837671] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
Kappa-opioid receptors (KOR) are widely expressed throughout the central nervous system, where they modulate a range of physiological processes depending on their location, including stress, mood, reward, pain, inflammation, and remyelination. However, clinical use of KOR agonists is limited by adverse effects such as dysphoria, aversion, and sedation. Within the drug-development field KOR agonists have been extensively investigated for the treatment of many centrally mediated nociceptive disorders including pruritis and pain. KOR agonists are potential alternatives to mu-opioid receptor (MOR) agonists for the treatment of pain due to their anti-nociceptive effects, lack of abuse potential, and reduced respiratory depressive effects, however, dysphoric side-effects have limited their widespread clinical use. Other diseases for which KOR agonists hold promising therapeutic potential include pruritis, multiple sclerosis, Alzheimer’s disease, inflammatory diseases, gastrointestinal diseases, cancer, and ischemia. This review highlights recent drug-development efforts targeting KOR, including the development of G-protein–biased ligands, mixed opioid agonists, and peripherally restricted ligands to reduce side-effects. We also highlight the current KOR agonists that are in preclinical development or undergoing clinical trials.
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11
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Zhang J, Zhou H, Li P, Shi H, Sui X, Wang Y, Shi J, Wang L. Hypothalamic response with PKA/CREB signaling is associated with direct cerebroventricular administration of bombesin-induced scratching. Brain Res 2022; 1789:147950. [PMID: 35618015 DOI: 10.1016/j.brainres.2022.147950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 04/29/2022] [Accepted: 05/19/2022] [Indexed: 11/28/2022]
Abstract
Bombesin (BN) is an itch-specific mediator that causes intense itch-scratching activity in mammals. Although most examinations of BN-induced itch processing have focused on the spinal cord, the involvement of central nervous system mechanisms remains unclear. Here, we investigated how relationships among hypothalamic regions regulate BN-mediated itch-scratch processes. We found that intracerebroventricular (i.c.v.) administration of BN (0.04-4 μg) elicited intense itch scratching in mice, whereas BN (0.4-400 μg) administered via intravenous tail injection failed to evoke a scratching response. Additionally, nalfurafine had no significant effects on BN-induced scratching behavior, indicating that central modulation of BN is distinct from histamine-mediated histaminergic itch and chloroquine-mediated non-histaminergic itch signaling pathways. We labeled BN with a fluorescent tag, 7-nitrobenz-2-oxa-1 (NBD), and traced its fluorescence in the hypothalamus for 30 min following i.c.v. NBD-BN administration. Accordingly, we confirmed that i.c.v. administration of BN enhanced c-Fos expression in the dorsal medial nucleus of the hypothalamus, where neuromedin B receptors and gastrin-releasing peptide receptors are highly expressed. Interestingly, in situ injection of BN into the hypothalamus immediately and robustly induced itch-scratching behavior. Moreover, gene transcripts and western blot assay revealed that BN receptor-dependent PKA/CREB signaling was upregulated in the hypothalamus after i.c.v. administration of BN. Consistently, pretreatment with a PKA inhibitor, Rp-cAMP, significantly reduced BN-induced scratching behavior. Our results indicate that the dorsal medial nucleus of the hypothalamus may be a key nucleus in mediating BN-mediated itch and hypothalamic PKA/CREB signaling is involved in regulating BN-mediated itch.
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Affiliation(s)
- Jingxin Zhang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China; The Key Laboratory of Basic Pharmacology of the Educational Minister, Zunyi Medical University, Zunyi, Guizhou 563000, China.
| | - Hu Zhou
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Pengfei Li
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Huaxiang Shi
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Xin Sui
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Yongan Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
| | - Jingshan Shi
- The Key Laboratory of Basic Pharmacology of the Educational Minister, Zunyi Medical University, Zunyi, Guizhou 563000, China.
| | - Liyun Wang
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
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12
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Chen C, Huang P, Bland K, Li M, Zhang Y, Liu-Chen LY. Agonist-Promoted Phosphorylation and Internalization of the Kappa Opioid Receptor in Mouse Brains: Lack of Connection With Conditioned Place Aversion. Front Pharmacol 2022; 13:835809. [PMID: 35652052 PMCID: PMC9149264 DOI: 10.3389/fphar.2022.835809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/31/2022] [Indexed: 12/30/2022] Open
Abstract
Selective kappa opioid receptor (KOR) agonists are promising antipruritic agents and analgesics. However, clinical development of KOR agonists has been limited by side effects, including psychotomimetic effects, dysphoria, and sedation, except for nalfurafine, and recently. CR845 (difelikefalin). Activation of KOR elicits G protein- and β-arrestin-mediated signaling. KOR-induced analgesic and antipruritic effects are mediated by G protein signaling. However, different results have been reported as to whether conditioned place aversion (CPA) induced by KOR agonists is mediated by β-arrestin signaling. In this study, we examined in male mice if there was a connection between agonist-promoted CPA and KOR phosphorylation and internalization, proxies for β-arrestin recruitment in vivo using four KOR agonists. Herein, we demonstrated that at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, promoted KOR phosphorylation at T363 and S369 in mouse brains, as detected by immunoblotting with phospho-KOR-specific antibodies. In addition, at doses producing maximal effective analgesic and antiscratch effects, U50,488H, MOM-SalB, and 42B, but not nalfurafine, caused KOR internalization in the ventral tegmental area of a mutant mouse line expressing a fusion protein of KOR conjugated at the C-terminus with tdTomato (KtdT). We have reported previously that the KOR agonists U50,488H and methoxymethyl salvinorin B (MOM-SalB) cause CPA, whereas nalfurafine and 42B do not, at doses effective for analgesic and antiscratch effects. Taken together, these data reveal a lack of connection between agonist-promoted KOR-mediated CPA with agonist-induced KOR phosphorylation and internalization in male mice.
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Affiliation(s)
- Chongguang Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Peng Huang
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Kathryn Bland
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Mengchu Li
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research and Department of Neural Sciences, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
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13
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Huskinson SL, Platt DM, Zamarripa CA, Dunaway K, Brasfield M, Prisinzano TE, Blough BE, Freeman KB. The G-protein biased kappa opioid agonists, triazole 1.1 and nalfurafine, produce non-uniform behavioral effects in male rhesus monkeys. Pharmacol Biochem Behav 2022; 217:173394. [DOI: 10.1016/j.pbb.2022.173394] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 03/07/2022] [Accepted: 04/28/2022] [Indexed: 11/26/2022]
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14
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French AR, van Rijn RM. An updated assessment of the translational promise of G-protein-biased kappa opioid receptor agonists to treat pain and other indications without debilitating adverse effects. Pharmacol Res 2022; 177:106091. [PMID: 35101565 PMCID: PMC8923989 DOI: 10.1016/j.phrs.2022.106091] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/14/2022] [Accepted: 01/18/2022] [Indexed: 01/22/2023]
Abstract
Kappa opioid receptor (κOR) agonists lack the abuse liability and respiratory depression effects of clinically used mu opioid receptor (μOR) analgesics and are hypothesized to be safer alternatives. However, κOR agonists have limiting adverse effects of their own, including aversion, sedation, and mood effects, that have hampered their clinical translation. Studies performed over the last 15 years have suggested that these adverse effects could result from activation of distinct intracellular signaling pathways that are dependent on β-arrestin, whereas signaling downstream of G protein activation produces antinociception. This led to the hypothesis that agonists biased away from β-arrestin signaling would have improved therapeutic windows over traditional unbiased agonists and allow for clinical development of analgesic G-protein-biased κOR agonists. Given a recent controversy regarding the benefits of G-protein-biased μOR agonists, it is timely to reassess the therapeutic promise of G-protein-biased κOR agonists. Here we review recent discoveries from preclinical κOR studies and critically evaluate the therapeutic windows of G-protein-biased κOR agonists in each of the adverse effects above. Overall, we find that G-protein-biased κOR agonists generally have improved therapeutic window relative to unbiased agonists, although frequently study design limits strong conclusions in this regard. However, a steady flow of newly developed biased κOR agonists paired with recently engineered behavioral and molecular tools puts the κOR field in a prime position to make major advances in our understanding of κOR function and fulfill the promise of translating a new generation of biased κOR agonists to the clinic.
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Affiliation(s)
- Alexander R French
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA; Purdue Institute for Drug Discovery, Purdue University, West Lafayette, IN 47907, USA.
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15
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Meariman JK, Sutphen JC, Gao J, Kapusta DR. Nalfurafine, a G-Protein-Biased KOR (Kappa Opioid Receptor) Agonist, Enhances the Diuretic Response and Limits Electrolyte Losses to Standard-of-Care Diuretics. Hypertension 2022; 79:379-390. [PMID: 34852633 PMCID: PMC8755620 DOI: 10.1161/hypertensionaha.121.18503] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nalfurafine is a G-protein-biased KOR (kappa opioid receptor) agonist that produces analgesia and lacks central nervous system adverse effects. Here, we examined the cardiovascular and renal responses to intravenous and oral nalfurafine alone and in combination with furosemide, hydrochlorothiazide, or amiloride. We hypothesized that nalfurafine, given its distinct mechanism of vasopressin inhibition, would increase urine output to these diuretics and limit electrolyte loss. Following catheterization, conscious Sprague-Dawley rats received an isotonic saline infusion and were then administered an intravenous bolus of nalfurafine, a diuretic, or a combination. Mean arterial pressure, heart rate, and urine output were recorded for 90 minutes. In another study, rats were placed in metabolic cages and administered drug in an oral volume load. Hourly urine samples were then collected for 5 hours. Intravenous and oral nalfurafine produced a marked diuresis, antinatriuresis, antikaliuresis, and a decrease in mean arterial pressure. Compared with diuretic treatment alone, intravenous coadministration with nalfurafine significantly increased urine output to furosemide and hydrochlorothiazide and decreased sodium and potassium excretion. Notably, mean arterial pressure was reduced with nalfurafine/diuretic combination therapy compared to diuretics alone. Similarly, oral coadministration of nalfurafine significantly increased urine output to hydrochlorothiazide and decreased sodium and potassium excretion, whereas combination with furosemide only limited the amount of sodium excreted. Further, both intravenous and oral coadministration of nalfurafine enhanced the diuresis to amiloride and decreased sodium excretion. Together, these findings demonstrate that nalfurafine enhances the diuresis to standard-of-care diuretics without causing an excessive loss of electrolytes, offering a new approach to treat several cardiovascular conditions.
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Affiliation(s)
- Jacob K Meariman
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112
| | - Jane C Sutphen
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112
| | - Juan Gao
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112
| | - Daniel R Kapusta
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112,Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112
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16
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Abstract
Nalfurafine has been used clinically in Japan for treatment of itch in kidney dialysis patients and in patients with chronic liver diseases. A one-year post-marketing study showed nalfurafine to be safe and efficacious without producing side effects of typical KOR agonists such as anhedonia and psychotomimesis. In this chapter, we summarize in vitro characterization and in vivo preclinical studies on nalfurafine. In vitro, nalfurafine is a highly potent and moderately selective KOR full agonist; however, whether it is a biased KOR agonist is a matter of debate. In animals, nalfurafine produced anti-pruritic effects in a dose range lower than that caused side effects, including conditioned place aversion (CPA), hypolocomotion, motor incoordination, consistent with the human data. In addition, nalfurafine showed antinociceptive effects in several pain models at doses that did not cause the side effects mentioned above. It appears to be effective against inflammatory pain and mechanical pain, but less so against thermal pain, particularly high-intensity thermal pain. U50,488H and nalfurafine differentially modulated several signaling pathways in a brain region-specific manners. Notably, U50,488H, but not nalfurafine, activated the mTOR pathway, which contributed to U50,488H-induced CPA. Because of its lack of side effects associated with typical KOR agonists, nalfurafine has been investigated as a combination therapy with an MOR ligand for pain treatment and for its effects on opioid use disorder and alcohol use disorder, and results indicate potential usefulness for these indications. Thus, although in vitro data regarding uniqueness of nalfurafine in terms of signaling at the KOR are somewhat equivocal, in vivo results support the assertion that nalfurafine is an atypical KOR agonist with a significantly improved side-effect profile relative to typical KOR agonists.
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17
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Agonist-promoted kappa opioid receptor (KOR) phosphorylation has behavioral endpoint-dependent and sex-specific effects. Neuropharmacology 2022; 202:108860. [PMID: 34736959 PMCID: PMC9122667 DOI: 10.1016/j.neuropharm.2021.108860] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023]
Abstract
We reported previously that the selective agonist U50,488H promoted phosphorylation of the mouse kappa opioid receptor (mKOR) in vitro at four residues in the C-terminal domain. In this study, we generated a mutant mouse line in which all the four residues were mutated to Ala (K4A) to examine the in vivo functional significance of agonist-induced KOR phosphorylation. U50,488H promoted KOR phosphorylation in brains of the wildtype (WT), but not K4A, male and female mice. Autoradiography of [3H] 69,593 binding to KOR in brain sections showed that WT and K4A mice had similar KOR distribution and expression levels in brain regions without sex differences. In K4A mice, U50,488H inhibited compound 48/80-induced scratching and attenuated novelty-induced hyperlocomotion to similar extents as in WT mice without sex differences. Interestingly, repeated pretreatment with U50,488H (80 mg/kg, s.c.) resulted in profound tolerance to the anti-scratch effects of U50,488H (5 mg/kg, s.c.) in WT mice of both sexes and female K4A mice, while in male K4A mice tolerance was attenuated. Moreover, U50,488H (2 mg/kg) induced conditioned place aversion (CPA) in WT mice of both sexes and male K4A mice, but not in female K4A mice. In contrast, U50,488H (5 mg/kg) caused CPA in male, but not female, mice, regardless of genotype. Thus, agonist-promoted KOR phosphorylation plays important roles in U50,488H-induced tolerance and CPA in a sex-dependent manner, without affecting acute U50,488H-induced anti-pruritic and hypo-locomotor effects. These results are the first to demonstrate sex differences in the effects of GPCR phosphorylation on the GPCR-mediated behaviors.
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18
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Paton KF, Robichon K, Templeton N, Denny L, Al Abadey A, Luo D, Prisinzano TE, La Flamme AC, Kivell BM. The Salvinorin Analogue, Ethoxymethyl Ether Salvinorin B, Promotes Remyelination in Preclinical Models of Multiple Sclerosis. Front Neurol 2021; 12:782190. [PMID: 34987466 PMCID: PMC8721439 DOI: 10.3389/fneur.2021.782190] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/03/2021] [Indexed: 12/24/2022] Open
Abstract
Multiple sclerosis is a neurodegenerative disease associated with demyelination and neuroinflammation in the central nervous system. There is an urgent need to develop remyelinating therapies to better treat multiple sclerosis and other demyelinating diseases. The kappa opioid receptor (KOR) has been identified as a potential target for the development of remyelinating therapies; however, prototypical KOR agonists, such as U50,488 have side effects, which limit clinical use. In the current study, we investigated a Salvinorin A analog, ethoxymethyl ether Salvinorin B (EOM SalB) in two preclinical models of demyelination in C57BL/6J mice. We showed that in cellular assays EOM SalB was G-protein biased, an effect often correlated with fewer KOR-mediated side effects. In the experimental autoimmune encephalomyelitis model, we found that EOM SalB (0.1-0.3 mg/kg) effectively decreased disease severity in a KOR-dependent manner and led to a greater number of animals in recovery compared to U50,488 treatment. Furthermore, EOM SalB treatment decreased immune cell infiltration and increased myelin levels in the central nervous system. In the cuprizone-induced demyelination model, we showed that EOM SalB (0.3 mg/kg) administration led to an increase in the number of mature oligodendrocytes, the number of myelinated axons and the myelin thickness in the corpus callosum. Overall, EOM SalB was effective in two preclinical models of multiple sclerosis and demyelination, adding further evidence to show KOR agonists are a promising target for remyelinating therapies.
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Affiliation(s)
- Kelly F. Paton
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Katharina Robichon
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Nikki Templeton
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Lisa Denny
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Afnan Al Abadey
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
| | - Dan Luo
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, United States
| | - Thomas E. Prisinzano
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, United States
| | - Anne C. La Flamme
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
- Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Bronwyn M. Kivell
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
- Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand
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Zamarripa CA, Pareek T, Schrock HM, Prisinzano TE, Blough BE, Sufka KJ, Freeman KB. The kappa-opioid receptor agonist, triazole 1.1, reduces oxycodone self-administration and enhances oxycodone-induced thermal antinociception in male rats. Psychopharmacology (Berl) 2021; 238:3463-3476. [PMID: 34430992 PMCID: PMC8629928 DOI: 10.1007/s00213-021-05965-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 08/10/2021] [Indexed: 12/29/2022]
Abstract
RATIONALE Triazole 1.1 is a novel kappa-opioid receptor (KOR) agonist reported to produce antinociception without KOR-typical adverse effects. When combined with the mu-opioid receptor (MOR) agonist, oxycodone, triazole 1.1 blocks oxycodone-induced pruritis without producing sedation-like effects in nonhuman primates. However, it is unknown if triazole 1.1 can reduce the abuse-related effects or enhance the antinociceptive effects of oxycodone similarly to other KOR agonists. OBJECTIVES The aim of the present study was to quantitatively compare the behavioral effects of triazole 1.1 to the KOR agonists, U50,488h and nalfurafine, on oxycodone self-administration and oxycodone-induced thermal antinociception when administered as mixtures with oxycodone. METHODS In the self-administration study, male Sprague-Dawley (SD) rats (n = 6) self-administered intravenous (i.v.) oxycodone alone (0.056 mg/kg/inj) or combined with U50,488 h (0.032-0.32 mg/kg/inj), nalfurafine (0.00032-0.0032 mg/kg/inj), or triazole 1.1 (0.32-1.8 mg/kg/inj) under a progressive-ratio schedule of reinforcement. In a hot plate assay, male SD rats (n = 6) received i.v. injections of oxycodone (1.0-5.6 mg/kg), U50,488h (1.0-18.0 mg/kg), nalfurafine (0.01-1.0 mg/kg), or triazole 1.1 (3.2-32.0 mg/kg) alone or in combinations of fixed proportion with oxycodone based on the relative potencies of the single drugs. Each study concluded with administration of the KOR antagonist nor-BNI and some degree of retesting of the previous conditions to verify that the behavioral effects were mediated by KOR activation. RESULTS All KOR agonists reduced oxycodone self-administration in a dose-dependent manner. Moreover, all single drugs and drug combinations produced dose-dependent, fully efficacious thermal antinociception. All KOR agonist:oxycodone combinations produced either additive or super-additive thermal antinociception. Finally, each KOR agonist was blocked in effect by nor-BNI in both behavioral measures. CONCLUSION This study demonstrates that triazole 1.1 reduces oxycodone's reinforcing effects and enhances oxycodone-induced antinociception to degrees that are comparable to typical KOR agonists. Given triazole 1.1's mild adverse-effect profile, developing MOR-KOR agonist combinations from the triazole 1.1 series may render new pain therapeutics with reduced abuse liability.
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Affiliation(s)
- C Austin Zamarripa
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
| | - Tanya Pareek
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
| | - Hayley M Schrock
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
| | | | | | - Kenneth J Sufka
- Department of Psychology, University of Mississippi, Oxford, MS, USA
| | - Kevin B Freeman
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA.
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20
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Barker KE, Lecznar AJ, Schumacher JM, Morris JS, Gutstein HB. Subanalgesic morphine doses augment fentanyl analgesia by interacting with delta opioid receptors in male rats. J Neurosci Res 2021; 100:149-164. [PMID: 34520585 DOI: 10.1002/jnr.24944] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 08/05/2021] [Indexed: 12/12/2022]
Abstract
Opioids are commonly used for the treatment of postoperative and post-traumatic pain; however, their therapeutic effectiveness is limited by undesirable and life-threatening side effects. Researchers have long attempted to develop opioid co-administration therapies that enhance analgesia, but the complexity of opioid analgesia and our incomplete mechanistic understanding has made this a daunting task. We discovered that subanalgesic morphine doses (100 ng/kg-10 µg/kg) augmented the acute analgesic effect of fentanyl (20 µg/kg) following subcutaneous drug co-administration to male rats. In addition, administration of equivalent drug ratios to naïve rat spinal cord membranes induced a twofold increase in G protein activation. The rate of GTP hydrolysis remained unchanged. We demonstrated that these behavioral and biochemical effects were mediated by the delta opioid receptor (DOP). Subanalgesic doses of the DOP-selective agonist SNC80 also augmented the acute analgesic effect of fentanyl. Furthermore, co-administration of the DOP antagonist naltrindole with both fentanyl-morphine and fentanyl-SNC80 combinations prevented augmentation of both analgesia and G protein activation. The mu opioid receptor (MOP) antagonist cyprodime did not block augmentation. Confocal microscopy of the substantia gelatinosa of rats treated with fentanyl, subanalgesic morphine, or this combination showed that changes in MOP internalization did not account for augmentation effects. Together, these findings suggest that augmentation of fentanyl analgesia by subanalgesic morphine is mediated by increased G protein activation resulting from a synergistic interaction between or heterodimerization of MOPs and DOPs. This finding is of great therapeutic significance because it suggests a strategy for the development of DOP-selective ligands that can enhance the therapeutic index of clinically used MOP drugs.
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Affiliation(s)
- Katherine E Barker
- Department of Anesthesiology, The University of Texas - MD Anderson Cancer Center, Houston, TX, USA
| | - Alynn J Lecznar
- Department of Anesthesiology, The University of Texas - MD Anderson Cancer Center, Houston, TX, USA
| | - Jill M Schumacher
- Department of Genetics, The University of Texas - MD Anderson Cancer Center, Houston, TX, USA
| | - Jeffrey S Morris
- Biostatistics Division, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, PA, USA
| | - Howard B Gutstein
- Anesthesiology Institute, Allegheny Health Network, Pittsburgh, PA, USA
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21
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Abstract
This paper is the forty-second consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2019 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY, 11367, United States.
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22
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Zhou Y, Liang Y. Involvement of GRK2 in modulating nalfurafine-induced reduction of excessive alcohol drinking in mice. Neurosci Lett 2021; 760:136092. [PMID: 34197905 DOI: 10.1016/j.neulet.2021.136092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 11/24/2022]
Abstract
Though it is well known that G protein-coupled receptor kinase 2 [GRK2] is involved in regulation of mu opioid receptor [MOR] desensitization and morphine-related behaviors, the potential role of GRK2 in regulation of kappa opioid receptor [KOR] functions in vivo has not been established yet. A couple of recent studies have found that GRK2 activity desensitizes KOR functions via decreasing G protein-coupled signaling with sensitizing arrestin-coupled signaling. Nalfurafine, a G protein-biased KOR full agonist, produces an inhibitory effect on alcohol intake in mice, with fewer side effects (sedation, aversion, or anxiety/depression-like behaviors). Using RNA sequencing (RNA-seq) analysis, we first identified that nuclear transcript level of grk2 [adrbk1] (but not other grks) was significantly up-regulated in mouse nucleus accumbens shell (NAcs) after chronic excessive alcohol drinking, suggesting alcohol specifically increased NAcs grk2 expression. We then tested whether selective GRK2/3 inhibitor CMPD101 could alter alcohol intake and found that CMPD101 alone had no effect on alcohol drinking. Therefore, we hypothesized that the grk2 increase in the NAcs could modulate the nalfurafine effect on alcohol intake via interacting with the G protein-mediated KOR signaling. Nalfurafine decreased alcohol drinking in a dose-related manner, and pretreatment with CMPD101 enhanced the reduction in alcohol intake induced by nalfurafine, indicating an involvement of GRK2/3 blockade in modulating G protein-biased KOR agonism of nalfurafine. Together, our study provides initial evidence relevant to the transcriptional change of grk2 gene in the NAc shell after excessive alcohol drinking. Pharmacological GRK2/3 blockade enhanced nalfurafine's efficacy, suggesting a GRK2/3-mediated mechanism, probably through the G protein-mediated KOR signaling.
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Affiliation(s)
- Yan Zhou
- Laboratory of the Biology of Addictive Diseases, USA.
| | - Yupu Liang
- Research Bioinformatics, CCTS, The Rockefeller University, NY, USA
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Che T, Dwivedi-Agnihotri H, Shukla AK, Roth BL. Biased ligands at opioid receptors: Current status and future directions. Sci Signal 2021; 14:14/677/eaav0320. [PMID: 33824179 DOI: 10.1126/scisignal.aav0320] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The opioid crisis represents a major worldwide public health crisis that has accelerated the search for safer and more effective opioids. Over the past few years, the identification of biased opioid ligands capable of eliciting selective functional responses has provided an alternative avenue to develop novel therapeutics without the side effects of current opioid medications. However, whether biased agonism or other pharmacological properties, such as partial agonism (or low efficacy), account for the therapeutic benefits remains questionable. Here, we provide a summary of the current status of biased opioid ligands that target the μ- and κ-opioid receptors and highlight advances in preclinical and clinical trials of some of these ligands. We also discuss an example of structure-based biased ligand discovery at the μ-opioid receptor, an approach that could revolutionize drug discovery at opioid and other receptors. Last, we briefly discuss caveats and future directions for this important area of research.
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Affiliation(s)
- Tao Che
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.
| | - Hemlata Dwivedi-Agnihotri
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Arun K Shukla
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA. .,National Institute of Mental Health Psychoactive Drug Screening Program, School of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27599, USA.,Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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24
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Effects of kappa opioid receptor agonists on fentanyl vs. food choice in male and female rats: contingent vs. non-contingent administration. Psychopharmacology (Berl) 2021; 238:1017-1028. [PMID: 33404739 DOI: 10.1007/s00213-020-05749-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 12/08/2020] [Indexed: 01/07/2023]
Abstract
RATIONALE Strategies are needed to decrease the abuse liability of mu opioid receptor (MOR) agonists. One strategy under consideration is to combine MOR agonists with kappa opioid receptor (KOR) agonists. OBJECTIVES The effects of KOR agonists (U50488, nalfurafine) on fentanyl-vs.-food choice were compared under conditions where the KOR agonists were added to the intravenously self-administered fentanyl (contingent delivery) or administered as subcutaneous pretreatments (non-contingent delivery) in male and female rats. METHODS Rats were trained to respond under a concurrent schedule of fentanyl (0, 0.32-10 μg/kg/infusion) and food reinforcement. In experiment 1, U50488 and nalfurafine were co-administered with fentanyl as fixed-proportion mixtures (contingent administration). In experiment 2, U50488 (1-10 mg/kg) and nalfurafine (3.2-32 μg/kg) were administered as acute pretreatments (non-contingent administration). The selective KOR antagonist, nor-BNI (32 mg/kg), was administered prior to contingent and non-contingent KOR-agonist treatment in experiment 3. RESULTS Both U50488 and nalfurafine decreased fentanyl choice when administered contingently, demonstrating that KOR agonists punish opioid choice. However, evidence for punishment corresponded with an elimination of operant responding in the majority of rats. Non-contingent U50488 and nalfurafine administration only decreased the number of choices made during the behavioral session without altering fentanyl choice. Contingent and non-contingent KOR-agonist effects on fentanyl choice were both attenuated by nor-BNI. CONCLUSIONS These results illustrate that the effects of KOR agonists on fentanyl reinforcement are dependent upon the contingencies under which they are administered.
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25
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Chen J, Wang G, Sun T, Ma C, Huo X, Kong Y. Involvement of TCF7L2 in generation of morphine-induced antinociceptive tolerance and hyperalgesia by modulating TLR4/ NF-κB/NLRP3 in microglia. Toxicol Appl Pharmacol 2021; 416:115458. [PMID: 33607128 DOI: 10.1016/j.taap.2021.115458] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/29/2021] [Accepted: 02/10/2021] [Indexed: 12/28/2022]
Abstract
Morphine is an opioid agonist and a nonselective mu, kappa and delta receptor agonist. It is a commonly used analgesic drug for the treatment of acute and chronic pain as well as cancer pain. Morphine is particularly important to address the problem of morphine tolerance. Tcf7l2, known as a risk gene for schizophrenia and autism, encodes a member of the LEF1/TCF transcription factor family. TCF7L2 is an important transcription factor that is upregulated in neuropathic pain models. However, the relationship between TCF7L2 and morphine tolerance has not been reported. In this study, we found that morphine tolerance led to the upregulation of TCF7L2 in the spinal cord, and also led to the upregulation of TCF7L2 expression in glial cells, which promoted inflammation related signal, and activated TLR4 / NF-κB/NLRP3 pathway. In addition, TCF7L2 regulated microglial cell activation induced by chronic morphine treatment. Mechanically, we found that TCF7L2 transcriptionally regulated TLR4 expression, and the depletion of TCF7L2 alleviated morphine tolerance induced by chronic morphine treatment, and further alleviated pain hypersensitivity induced by chronic morphine treatment. We therefore suggested that TCF7L2 regulates the activation of TLR4/ NF-κB/NLRP3 pathway in microglia, and is involved in the formation of morphine tolerance. Our results provide a new idea for the regulation mechanism of morphine tolerance.
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Affiliation(s)
- Jing Chen
- Department of Anesthesiology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province 150081, China
| | - Guonian Wang
- Harbin Medical University Sino-Russian Research Center Pain Management Research Institute, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province 150001, China.
| | - Tingting Sun
- Department of Anesthesiology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province 150081, China
| | - Chao Ma
- Department of Anesthesiology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province 150081, China
| | - Xing Huo
- Department of Anesthesiology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province 150081, China
| | - Yiran Kong
- Department of Anesthesiology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province 150081, China
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26
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Kaski SW, White AN, Gross JD, Siderovski DP. Potential for Kappa-Opioid Receptor Agonists to Engineer Nonaddictive Analgesics: A Narrative Review. Anesth Analg 2021; 132:406-419. [PMID: 33332902 DOI: 10.1213/ane.0000000000005309] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A serious adverse effect of prescription opioid analgesics is addiction, both to these analgesics and to illicit drugs like heroin that also activate the µ-opioid receptor (MOR). Opioid use disorder (OUD) and opioid overdose deaths represent a current American health crisis, and the prescription of opioid analgesics has contributed significantly to this crisis. While prescription opioids are highly effective analgesics, there currently exists no facile way to use them for extended periods without the risk of addiction. If addiction caused by MOR-targeting analgesics could be blocked by blending in a new "antiaddiction" ingredient that does not diminish analgesia and does not introduce its own therapeutically limiting side effects, then continued clinical use of prescription opioids for treating pain could be maintained (or even enhanced) instead of curtailed. In this narrative review, we contextualize this hypothesis, first with a brief overview of the current American opioid addiction crisis. The neurobiology of 2 key receptors in OUD development, MOR and the κ-opioid receptor (KOR), is then discussed to highlight the neuroanatomical features and circuitry in which signal transduction from these receptors lie in opposition-creating opportunities for pharmacological intervention in curtailing the addictive potential of MOR agonism. Prior findings with mixed MOR/KOR agonists are considered before exploring new potential avenues such as biased KOR agonists. New preclinical data are highlighted, demonstrating that the G protein-biased KOR agonist nalfurafine reduces the rewarding properties of MOR-targeting analgesics and enhances MOR-targeting analgesic-induced antinociception. Finally, we discuss the recent discovery that a regulator of G protein signaling (namely, RGS12) is a key component of signaling bias at KOR, presenting another drug discovery target toward identifying a single agent or adjuvant to be added to traditional opioid analgesics that could reduce or eliminate the addictive potential of the latter drug.
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Affiliation(s)
- Shane W Kaski
- From the Departments of Neuroscience and Behavioral Medicine & Psychiatry, West Virginia University, Morgantown, West Virginia
| | - Allison N White
- From the Departments of Neuroscience and Behavioral Medicine & Psychiatry, West Virginia University, Morgantown, West Virginia
| | - Joshua D Gross
- Department of Cell Biology, Duke University Medical Center, Durham, North Carolina
| | - David P Siderovski
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas
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Evaluation of Antinociceptive Effects of Chitosan-Coated Liposomes Entrapping the Selective Kappa Opioid Receptor Agonist U50,488 in Mice. ACTA ACUST UNITED AC 2021; 57:medicina57020138. [PMID: 33557245 PMCID: PMC7913921 DOI: 10.3390/medicina57020138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 01/30/2021] [Accepted: 02/01/2021] [Indexed: 11/17/2022]
Abstract
Background and Objectives: The selective kappa opioid receptor agonist U50,488 was reported to have analgesic, cough suppressant, diuretic and other beneficial properties. The aim of our study was to analyze the effects of some original chitosan-coated liposomes entrapping U50,488 in somatic and visceral nociceptive sensitivity in mice. Materials and Methods: The influence on the somatic pain was assessed using a tail flick test by counting the tail reactivity to thermal noxious stimulation. The nociceptive visceral estimation was performed using the writhing test in order to evaluate the behavioral manifestations occurring as a reaction to the chemical noxious peritoneal irritation with 0.6% acetic acid (10 mL/kbw). The animals were treated orally, at the same time, with a single dose of: distilled water 0.1 mL/10 gbw; 50 mg/kbw U50,488; 50 mg/kbw U50,488 entrapped in chitosan-coated liposomes, according to the group they were randomly assigned. Results: The use of chitosan-coated liposomesas carriers for U50,488 induced antinociceptive effects that began to manifest after 2 h, andwere prolonged but with a lower intensity than those caused by the free selective kappa opioid in both tests. Conclusion: In this experimental model, the oral administration of nanovesicles containing the selective kappa opioid agonist U50,488 determined a prolonged analgesic outcome in the tail flick test, as well as in the writhing test.
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28
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Denny L, Al Abadey A, Robichon K, Templeton N, Prisinzano TE, Kivell BM, La Flamme AC. Nalfurafine reduces neuroinflammation and drives remyelination in models of CNS demyelinating disease. Clin Transl Immunology 2021; 10:e1234. [PMID: 33489124 PMCID: PMC7811802 DOI: 10.1002/cti2.1234] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/22/2020] [Accepted: 12/14/2020] [Indexed: 12/31/2022] Open
Abstract
Objectives Multiple sclerosis (MS) is a neurodegenerative disease characterised by inflammation and damage to the myelin sheath, resulting in physical and cognitive disability. There is currently no cure for MS, and finding effective treatments to prevent disease progression has been challenging. Recent evidence suggests that activating kappa opioid receptors (KOR) has a beneficial effect on the progression of MS. Although many KOR agonists like U50,488 are not suitable for clinical use because of a poor side‐effect profile, nalfurafine is a potent, clinically used KOR agonist with a favorable side‐effect profile. Methods Using the experimental autoimmune encephalomyelitis (EAE) model, the effect of therapeutically administered nalfurafine or U50,488 on remyelination, CNS infiltration and peripheral immune responses were compared. Additionally, the cuprizone model was used to compare the effects on non‐immune demyelination. Results Nalfurafine enabled recovery and remyelination during EAE. Additionally, it was more effective than U50,488 and promoted disease reduction when administered after chronic demyelination. Blocking KOR with the antagonist, nor‐BNI, impaired full recovery by nalfurafine, indicating that nalfurafine mediates recovery from EAE in a KOR‐dependent fashion. Furthermore, nalfurafine treatment reduced CNS infiltration (especially CD4+ and CD8+ T cells) and promoted a more immunoregulatory environment by decreasing Th17 responses. Finally, nalfurafine was able to promote remyelination in the cuprizone demyelination model, supporting the direct effect on remyelination in the absence of peripheral immune cell invasion. Conclusions Overall, our findings support the potential of nalfurafine to promote recovery and remyelination and highlight its promise for clinical use in MS.
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Affiliation(s)
- Lisa Denny
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand
| | - Afnan Al Abadey
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand
| | - Katharina Robichon
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand
| | - Nikki Templeton
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand
| | - Thomas E Prisinzano
- Department of Pharmaceutical Sciences University of Kentucky Lexington KY 40536 USA
| | - Bronwyn M Kivell
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand
| | - Anne C La Flamme
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand.,Centre for Biodiscovery Victoria University of Wellington Wellington New Zealand.,Malaghan Institute of Medical Research Wellington New Zealand
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29
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Abstract
Preclinical models that assess "pain" in rodents typically measure increases in behaviors produced by a "pain stimulus." A large literature exists showing that kappa opioid receptor (KOR) agonists can decrease these "pain-stimulated behaviors" following many different pain stimuli. Despite showing apparent antinociceptive properties in these preclinical models, KOR agonists failed as analgesics in clinical trials. Recent studies that assessed decreases in behavior due to a pain stimulus show that KOR agonists are not effective in restoring these "pain-depressed behaviors" to normal levels, which agrees with the lack of effectiveness for KOR agonists in clinical trials. One current explanation for the failure of previous KOR agonists in clinical trials is that those agonists activated beta-arrestin signaling and that KOR agonists with a greater bias for G protein signaling will be more successful. However, neither G protein-biased agonists nor beta-arrestin-biased agonists are very effective in assays of pain-depressed behavior, which suggests that novel biased agonists may still not be effective analgesics. This review provides a concise account of the effectiveness of KOR agonists in preclinical models of pain-stimulated and pain-depressed behaviors following the administration of different pain stimuli. Based on the previous results, it may be appropriate to include both behaviors when testing the analgesic potential of KOR agonists.
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Affiliation(s)
- Matthew F Lazenka
- Department of Biology and Chemistry, Liberty University, Lynchburg, VA, USA.
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30
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Cao D, Huang P, Chiu YT, Chen C, Wang H, Li M, Zheng Y, Ehlert FJ, Zhang Y, Liu-Chen LY. Comparison of Pharmacological Properties between the Kappa Opioid Receptor Agonist Nalfurafine and 42B, Its 3-Dehydroxy Analogue: Disconnect between in Vitro Agonist Bias and in Vivo Pharmacological Effects. ACS Chem Neurosci 2020; 11:3036-3050. [PMID: 32897695 DOI: 10.1021/acschemneuro.0c00407] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Nalfurafine, a moderately selective kappa opioid receptor (KOR) agonist, is used in Japan for treatment of itch without causing dysphoria or psychotomimesis. Here we characterized the pharmacology of compound 42B, a 3-dehydroxy analogue of nalfurafine and compared with that of nalfurafine. Nalfurafine and 42B acted as full KOR agonists and partial μ opioid receptor (MOR) agonists, but 42B showed much lower potency for both receptors and lower KOR/MOR selectivity, different from previous reports. Molecular modeling revealed that water-mediated hydrogen-bond formation between 3-OH of nalfurafine and KOR accounted for its higher KOR potency than 42B. The higher potency of both at KOR over MOR may be due to hydrogen-bond formation between nonconserved Y7.35 of KOR and their carbonyl groups. Both showed modest G protein signaling biases. In mice, like nalfurafine, 42B produced antinociceptive and antiscratch effects and did not cause conditioned place aversion (CPA) in the effective dose ranges. Unlike nalfurafine, 42B caused motor incoordination and hypolocomotion. As both agonists showed G protein biases, yet produced different effects on locomotor activity and motor incoordination, the findings and those in the literature suggest caution in correlating in vitro biochemical data with in vivo behavior effects. The factors contributing to the disconnect, including pharmacodynamic and pharmacokinetic issues, are discussed. In addition, our results suggest that among the KOR-induced adverse behaviors, CPA can be separated from motor incoordination and hypolocomotion.
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Affiliation(s)
- Danni Cao
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
- Beijing Key Laboratory of Neuropsychopharmacology, State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, 100850, China
| | - Peng Huang
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Yi-Ting Chiu
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Chongguang Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
| | - Huiqun Wang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Mengchu Li
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Yi Zheng
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Frederick J. Ehlert
- Department of Pharmaceutical Sciences, Center of Health Sciences, University of California, Irvine, California 92697, United States
| | - Yan Zhang
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Lee-Yuan Liu-Chen
- Center for Substance Abuse Research, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140, United States
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31
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Paton KF, Atigari DV, Kaska S, Prisinzano T, Kivell BM. Strategies for Developing κ Opioid Receptor Agonists for the Treatment of Pain with Fewer Side Effects. J Pharmacol Exp Ther 2020; 375:332-348. [PMID: 32913006 DOI: 10.1124/jpet.120.000134] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/27/2020] [Indexed: 12/21/2022] Open
Abstract
There is significant need to find effective, nonaddictive pain medications. κ Opioid receptor (KOPr) agonists have been studied for decades but have recently received increased attention because of their analgesic effects and lack of abuse potential. However, a range of side effects have limited the clinical development of these drugs. There are several strategies currently used to develop safer and more effective KOPr agonists. These strategies include identifying G-protein-biased agonists, developing peripherally restricted KOPr agonists without centrally mediated side effects, and developing mixed opioid agonists, which target multiple receptors at specific ratios to balance side-effect profiles and reduce tolerance. Here, we review the latest developments in research related to KOPr agonists for the treatment of pain. SIGNIFICANCE STATEMENT: This review discusses strategies for developing safer κ opioid receptor (KOPr) agonists with therapeutic potential for the treatment of pain. Although one strategy is to modify selective KOPr agonists to create peripherally restricted or G-protein-biased structures, another approach is to combine KOPr agonists with μ, δ, or nociceptin opioid receptor activation to obtain mixed opioid receptor agonists, therefore negating the adverse effects and retaining the therapeutic effect.
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Affiliation(s)
- Kelly F Paton
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Diana V Atigari
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Sophia Kaska
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Thomas Prisinzano
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
| | - Bronwyn M Kivell
- School of Biological Sciences, Centre for Biodiscovery, Victoria University of Wellington, Wellington, New Zealand (K.P., D.V.A., B.M.K.) and Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky (S.K., T.P.)
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The kappa-opioid receptor agonist, nalfurafine, blocks acquisition of oxycodone self-administration and oxycodone's conditioned rewarding effects in male rats. Behav Pharmacol 2020; 31:792-797. [PMID: 32804774 DOI: 10.1097/fbp.0000000000000581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mu-opioid receptor (MOR) agonists are highly efficacious for the treatment of pain but have significant abuse liability. Recently, we reported that nalfurafine, when combined with oxycodone at a certain ratio, reduced the reinforcing effects of oxycodone in rats while producing additive antinociceptive effects. Questions remain, however, including if the combination will function as a reinforcer in drug-naïve rats, and if the combination produces aversive effects that could explain nalfurafine's ability to reduce oxycodone self-administration? In the present study, we investigated nalfurafine's ability to reduce acquisition of oxycodone self-administration when the two were self-administered as a mixture in drug-naïve rats and nalfurafine's ability to attenuate a conditioned place preference (CPP) induced by oxycodone. In the self-administration study, male Sprague-Dawley rats self-administered intravenous injections of oxycodone (0.056 mg/kg/injection), an oxycodone/nalfurafine combination (0.056/0.0032 mg/kg/injection), or saline under fixed-ratio schedules of reinforcement for 20 days to compare rates of acquisition of drug taking. In the CPP assay, male Sprague-Dawley rats received subcutaneous injections of either saline, oxycodone (3.2 mg/kg), nalfurafine (0.18 mg/kg), or an oxycodone/nalfurafine combination at the same ratio used in the self-administration study (3.2 mg/kg/0.18 mg/kg). All subjects self-administering oxycodone alone met acquisition criteria. However, only 13% of subjects self-administering oxycodone/nalfurafine met criteria, and no subjects acquired self-administration of saline. Oxycodone, but not nalfurafine alone or the oxycodone/nalfurafine combination, produced rewarding effects in rats in the CPP test. These findings suggest that the combination of oxycodone and nalfurafine will be less habit forming in opioid-naïve patients than oxycodone alone.
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Paton KF, Biggerstaff A, Kaska S, Crowley RS, La Flamme AC, Prisinzano TE, Kivell BM. Evaluation of Biased and Balanced Salvinorin A Analogs in Preclinical Models of Pain. Front Neurosci 2020; 14:765. [PMID: 32792903 PMCID: PMC7385413 DOI: 10.3389/fnins.2020.00765] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 06/29/2020] [Indexed: 01/09/2023] Open
Abstract
In the search for safer, non-addictive analgesics, kappa opioid receptor (KOPr) agonists are a potential target, as unlike mu-opioid analgesics, they do not have abuse potential. Salvinorin A (SalA) is a potent and selective KOPr agonist, however, clinical utility is limited by the short duration of action and aversive side effects. Biasing KOPr signaling toward G-protein activation has been highlighted as a key cellular mechanism to reduce the side effects of KOPr agonists. The present study investigated KOPr signaling bias and the acute antinociceptive effects and side effects of two novel analogs of SalA, 16-Bromo SalA and 16-Ethynyl SalA. 16-Bromo SalA showed G-protein signaling bias, whereas 16-Ethynyl SalA displayed balanced signaling properties. In the dose-response tail-withdrawal assay, SalA, 16-Ethynyl SalA and 16-Bromo SalA were more potent than the traditional KOPr agonist U50,488, and 16-Ethynyl SalA was more efficacious. 16-Ethynyl SalA and 16-Bromo SalA both had a longer duration of action in the warm water tail-withdrawal assay, and 16-Ethynyl had greater antinociceptive effect in the hot-plate assay, compared to SalA. In the intraplantar 2% formaldehyde test, 16-Ethynyl SalA and 16-Bromo SalA significantly reduced both nociceptive and inflammatory pain-related behaviors. Moreover, 16-Ethynyl SalA and 16-Bromo SalA had no anxiogenic effects in the marble burying task, and 16-Bromo SalA did not alter behavior in the elevated zero maze. Overall, 16-Ethynyl SalA significantly attenuated acute pain-related behaviors in multiple preclinical models, while the biased KOPr agonist, 16-Bromo SalA, displayed modest antinociceptive effects, and lacked anxiogenic effects.
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Affiliation(s)
- Kelly F Paton
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
| | - Andrew Biggerstaff
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
| | - Sophia Kaska
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, United States
| | - Rachel S Crowley
- Department of Medicinal Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, United States
| | - Anne C La Flamme
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand.,Malaghan Institute of Medical Research, Wellington, New Zealand
| | - Thomas E Prisinzano
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, United States.,Department of Medicinal Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS, United States
| | - Bronwyn M Kivell
- School of Biological Sciences, Centre for Biodiscovery, Faculty of Science, Victoria University of Wellington, Wellington, New Zealand
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Huskinson SL, Platt DM, Brasfield M, Follett ME, Prisinzano TE, Blough BE, Freeman KB. Quantification of observable behaviors induced by typical and atypical kappa-opioid receptor agonists in male rhesus monkeys. Psychopharmacology (Berl) 2020; 237:2075-2087. [PMID: 32372348 PMCID: PMC7308209 DOI: 10.1007/s00213-020-05519-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 04/01/2020] [Indexed: 12/20/2022]
Abstract
RATIONALE Kappa-opioid receptor (KOR) agonists are antinociceptive but have side effects that limit their therapeutic utility. New KOR agonists have been developed that are fully efficacious at the KOR but may produce fewer or reduced side effects that are typical of KOR agonists. OBJECTIVES We determined behavioral profiles for typical and atypical KOR agonists purported to differ in intracellular-signaling profiles as well as a mu-opioid receptor (MOR) agonist, oxycodone, using a behavioral scoring system based on Novak et al. (Am J Primatol 28:124-138, 1992, Am J Primatol 46:213-227, 1998) and modified to quantify drug-induced effects (e.g., Duke et al. J Pharmacol Exp Ther 366:145-157, 2018). METHODS Six adult male rhesus monkeys were administered a range of doses of the typical KOR agonists, U50-488H (0.0032-0.1 mg/kg) and salvinorin A (0.00032-0.01 mg/kg); the atypical KOR agonists, nalfurafine (0.0001-0.001 mg/kg) and triazole 1.1 (0.01-0.32 mg/kg); the MOR agonist, oxycodone (0.0032-0.32 mg/kg); and as controls, cocaine (0.032-0.32 mg/kg) and ketamine (0.32-10 mg/kg). For time-course determinations, the largest dose of each KOR agonist or MOR agonist was administered across timepoints (10-320 min). In mixture conditions, oxycodone (0.1 mg/kg) was followed by KOR-agonist administration. RESULTS Typical KOR agonists produced sedative-like and motor-impairing effects. Nalfurafine was similar to typical KOR agonists on most outcomes, and triazole 1.1 produced no effects on its own except for reducing scratch during time-course determinations. In the mixture, all KOR agonists reduced oxycodone-induced scratching, U50-488H and nalfurafine reduced species-typical activity, and U50-488H increased rest/sleep posture. CONCLUSIONS Atypical "biased" KOR agonists produce side-effect profiles that are relatively benign (triazole 1.1) or reduced (nalfurafine) compared to typical KOR agonists.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Diterpenes, Clerodane/pharmacology
- Dose-Response Relationship, Drug
- Macaca mulatta
- Male
- Morphinans/pharmacology
- Motor Activity/drug effects
- Motor Activity/physiology
- Oxycodone/pharmacology
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/physiology
- Spiro Compounds/pharmacology
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Affiliation(s)
- S L Huskinson
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, 39216, USA.
| | - D M Platt
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - M Brasfield
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - M E Follett
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - T E Prisinzano
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, KY, 40536, USA
| | - B E Blough
- Research Triangle Institute, Research Triangle Park, NC, 27709, USA
| | - K B Freeman
- Division of Neurobiology and Behavior Research, Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, 39216, USA
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Kappa opioid agonists reduce oxycodone self-administration in male rhesus monkeys. Psychopharmacology (Berl) 2020; 237:1471-1480. [PMID: 32006048 PMCID: PMC7196516 DOI: 10.1007/s00213-020-05473-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 01/21/2020] [Indexed: 12/12/2022]
Abstract
RATIONALE Combinations of mu and kappa opioid receptor (KOR) agonists have been proposed as potential analgesic formulations with reduced abuse liability. The current studies extend previous work by investigating the typical KOR agonist, salvinorin A, and the atypical KOR agonist, nalfurafine, as deterrents of oxycodone self-administration using a progressive ratio (PR) schedule of reinforcement. METHODS In separate experiments, adult male rhesus monkeys (N = 4/experiment) were trained under a PR schedule of reinforcement to self-administer cocaine (0.1 mg/kg/injection) and saline on alternating days. Oxycodone (0.01-0.1 mg/kg/injection) alone and combined with salvinorin A (experiment 1; 0.006, 0.012 mg/kg/injection) or nalfurafine (experiment 2; 0.0001-0.00032 mg/kg/injection) were tested within the alternating cocaine and saline baseline. The mechanism of nalfurafine's effects on oxycodone self-administration was investigated via pretreatment with the KOR antagonist, nor-binaltorphimine (nor-BNI; 10 mg/kg; i.m.). RESULTS All subjects self-administered oxycodone alone above saline levels at sufficiently large doses, and combining salvinorin A or nalfurafine with oxycodone reduced the mean number of injections per session to saline levels (experiment 1) or to levels that were significantly lower than oxycodone alone (experiment 2). The ability of nalfurafine to reduce oxycodone self-administration was reversed by pretreatment with nor-BNI. CONCLUSIONS These results demonstrate that KOR agonists, including the clinically used KOR agonist, nalfurafine, can punish self-administration of a prescription opioid analgesic, oxycodone, in rhesus monkeys and that nalfurafine's punishing effect is KOR-dependent. Combinations of KOR agonists with prescription opioids may have reduced abuse liability.
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Brust TF. Biased Ligands at the Kappa Opioid Receptor: Fine-Tuning Receptor Pharmacology. Handb Exp Pharmacol 2020; 271:115-135. [PMID: 33140224 DOI: 10.1007/164_2020_395] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The kappa opioid receptor (KOR) is a G protein-coupled receptor (GPCR) that can signal through multiple signaling pathways. KOR agonists are known to relieve pain and itch, as well as induce dysphoria, sedation, hallucinations, and diuresis. As is the case with many other GPCRs, specific signaling pathways downstream of the KOR have been linked to certain physiological responses induced by the receptor. Those studies motivated the search and discovery of a number of KOR ligands that preferentially activate one signaling pathway over another. Such compounds are termed functionally selective or biased ligands, and may present a way of inducing desired receptor effects with reduced adverse reactions. In this chapter, I review the molecular intricacies of KOR signaling and discuss the studies that have used biased signaling through the KOR as a way to selectively modulate in vivo physiology.
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Affiliation(s)
- Tarsis F Brust
- Department of Pharmaceutical Sciences, Lloyd L. Gregory School of Pharmacy, Palm Beach Atlantic University, West Palm Beach, FL, USA.
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