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Yuan Y, Xu T, Huang Y, Shi J. Strategies for developing μ opioid receptor agonists with reduced adverse effects. Bioorg Chem 2024; 149:107507. [PMID: 38850778 DOI: 10.1016/j.bioorg.2024.107507] [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] [Received: 03/22/2024] [Revised: 05/02/2024] [Accepted: 05/28/2024] [Indexed: 06/10/2024]
Abstract
Opioids are currently the most effective and widely used painkillers in the world. Unfortunately, the clinical use of opioid analgesics is limited by serious adverse effects. Many researchers have been working on designing and optimizing structures in search of novel μ opioid receptor(MOR) agonists with improved analgesic activity and reduced incidence of adverse effects. There are many strategies to develop MOR drugs, mainly focusing on new low efficacy agonists (potentially G protein biased agonists), MOR agonists acting on different Gα subtype, targeting opioid receptors in the periphery, acting on multiple opioid receptor, and targeting allosteric sites of opioid receptors, and others. This review summarizes the design methods, clinical applications, and structure-activity relationships of small-molecule agonists for MOR based on these different design strategies, providing ideas for the development of safer novel opioid ligands with therapeutic potential.
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Affiliation(s)
- Yan Yuan
- College of Life Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 611756, China
| | - Ting Xu
- Department of Anesthesiology, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Yu Huang
- College of Life Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 611756, China
| | - Jianyou Shi
- Department of Pharmacy, Personalized Drug Therapy Key Laboratory of Sichuan Province, Sichuan Academy of Medical Science & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China.
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2
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Younes S. The relationship between gender and pharmacology. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2024; 7:100192. [PMID: 39101002 PMCID: PMC11295939 DOI: 10.1016/j.crphar.2024.100192] [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: 04/14/2024] [Revised: 05/28/2024] [Accepted: 06/11/2024] [Indexed: 08/05/2024] Open
Abstract
The part of sexuality in pharmacology research was not acknowledged, and it was not thought-out to be a determinant that could impact strength and disease. For decades research has mainly contained male, women and animals, leading to a lack of news about syndromes in females. Still, it is critical to guarantee equal likeness so that determine the security, influence, and resistance of healing agents for all individuals. The underrepresentation of female models in preclinical studies over various decades has surpassed to disparities in the understanding, disease, and treatment of ailments 'tween genders. The closeness of sexuality bias has happened recognized as a contributing determinant to the restricted interpretation and replicability of preclinical research. Many demands operation have stressed the significance of including sexuality as a organic changeable, and this view is acquire growing support. Regardless of important progress in incorporating more female models into preclinical studies, differences prevail contemporary. The current review focuses on the part of sexuality and common in biomedical research and, therefore, their potential function in pharmacology and analyze the potential risks guide.
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Affiliation(s)
- Samer Younes
- Department of Pharmacy, Tartous University, Syria
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3
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Zhang M, Xu B, Li N, Zhang Q, Chen D, Wu S, Yu B, Zhang X, Hu X, Zhang S, Jing Y, Yang Z, Jiang J, Fang Q. All-Hydrocarbon Stapled Peptide Multifunctional Agonists at Opioid and Neuropeptide FF Receptors: Highly Potent, Long-Lasting Brain Permeant Analgesics with Diminished Side Effects. J Med Chem 2023; 66:17138-17154. [PMID: 38095323 DOI: 10.1021/acs.jmedchem.3c02093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Our previous study reported the multifunctional agonist for opioid and neuropeptide FF receptors DN-9, along with its cyclic peptide analogues c[D-Cys2, Cys5]-DN-9 and c[D-Lys2, Asp5]-DN-9. These analogues demonstrated potent antinociceptive effects with reduced opioid-related side effects. To develop more stable and effective analgesics, we designed, synthesized, and evaluated seven hydrocarbon-stapled cyclic peptides based on DN-9. In vitro calcium mobilization assays revealed that most of the stapled peptides, except 3, displayed multifunctional agonistic activities at opioid and neuropeptide FF receptors. Subcutaneous administration of all stapled peptides resulted in effective and long-lasting antinociceptive activities lasting up to 360 min. Among these stapled peptides, 1a and 1b emerged as the optimized compounds, producing potent central antinociception following subcutaneous, intracerebroventricular, and oral administrations. Additionally, subcutaneous administration of 1a and 1b caused nontolerance antinociception, with limited occurrence of constipation and addiction. Furthermore, 1a was selected as the final optimized compound due to its wider safety window compared to 1b.
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Affiliation(s)
- Mengna Zhang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Biao Xu
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Ning Li
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Qinqin Zhang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Dan Chen
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Shuyuan Wu
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Bowen Yu
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Xiaodi Zhang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Xuanran Hu
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Shichao Zhang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Yuhong Jing
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Zhenyun Yang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
| | - Jinhong Jiang
- Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, 209 Tongshan Rd, Xuzhou, Jiangsu 221004, China
| | - Quan Fang
- Institute of Physiology, School of Basic Medical Sciences, and State Key Laboratory of Animal Disease Control and Prevention, College of Veterinary Medicine, Lanzhou University, 199 Donggang West Road, Lanzhou 730000, PR China
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Allegra S, Chiara F, Di Grazia D, Gaspari M, De Francia S. Evaluation of Sex Differences in Preclinical Pharmacology Research: How Far Is Left to Go? Pharmaceuticals (Basel) 2023; 16:786. [PMID: 37375734 DOI: 10.3390/ph16060786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/10/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Until the last quarter of the 20th century, sex was not recognized as a variable in health research, nor was it believed to be a factor that could affect health and illness. Researchers preferred studying male models for a variety of reasons, such as simplicity, lower costs, hormone confounding effects, and fear of liability from perinatal exposure in case of pregnancy. Equitable representation is imperative for determining the safety, effectiveness, and tolerance of therapeutic agents for all consumers. Decades of female models' underrepresentation in preclinical studies has resulted in inequality in the understanding, diagnosis, and treatment of disease between the sexes. Sex bias has been highlighted as one of the contributing factors to the poor translation and replicability of preclinical research. There have been multiple calls for action, and the inclusion of sex as a biological variable is increasingly supported. However, although there has been substantial progress in the efforts to include more female models in preclinical studies, disparities today remain. In the present review, we consider the current standard practice of the preclinical research setting, why the sex bias exists, why there is the need to include female models, and what risks may arise from continuing this exclusion from experimental design.
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Affiliation(s)
- Sarah Allegra
- Department of Biological and Clinical Sciences, University of Turin, S. Luigi Gonzaga Hospital, 10043 Orbassano, Italy
| | - Francesco Chiara
- Department of Biological and Clinical Sciences, University of Turin, S. Luigi Gonzaga Hospital, 10043 Orbassano, Italy
| | - Daniela Di Grazia
- Department of Biological and Clinical Sciences, University of Turin, S. Luigi Gonzaga Hospital, 10043 Orbassano, Italy
| | - Marco Gaspari
- Department of Biological and Clinical Sciences, University of Turin, S. Luigi Gonzaga Hospital, 10043 Orbassano, Italy
| | - Silvia De Francia
- Department of Biological and Clinical Sciences, University of Turin, S. Luigi Gonzaga Hospital, 10043 Orbassano, Italy
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Altarifi AA, Younis BA, Nuseir KQ, Al-Mousa AA, Qaoud AK, Alsalem MI, Neubert JK. Preclinical comparison of antinociceptive effects between ibuprofen, diclofenac, naproxen, and acetaminophen on acid-stimulated body stretching and acid-depressed feeding behaviors in rats. Behav Pharmacol 2022; 33:567-574. [PMID: 36256732 DOI: 10.1097/fbp.0000000000000704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Pain is a major problem that burdens the health and economy of societies worldwide. Nonsteroidal anti-inflammatory drugs (NSAIDs) are over-the-counter medications that are widely indicated for mild to moderate pain conditions. Clinically, the selection of a medication among this class is mainly based according to both patient's and doctor's previous experiences. Herein, we studied differences in therapeutic efficacies among the most commonly prescribed NSAIDs and acetaminophen in inflammatory pain rat model. Body stretching and food consumption behaviors were assessed after intraperitoneal administration of lactic acid. Initially, different concentrations of lactic acid were evaluated in adult male rats in both behavioral models. Acid concentrations of 1.8 and 3.2% were selected to assess the effects of ibuprofen, diclofenac, naproxen, and acetaminophen in body stretching and feeding behaviors, respectively. In the feeding study, food restriction for 1-24 h prior to feeding studies was assessed at first, and 24 h was selected for further tests. Acetaminophen (100 mg/kg), diclofenac (10 mg/kg), ibuprofen (10-32 mg/kg), and naproxen (3.2-10 mg/kg) significantly decreased acid-stimulated body stretching. Likewise, acetaminophen (100 mg/kg), diclofenac (10 mg/kg), and ibuprofen (32 mg/kg) increased food consumption significantly after 3.2% lactic acid. There were no significant differences between different test drugs efficacies in both stretching and feeding behaviors. In conclusion, feeding behavior provides a good appraisal for pain and analgesic drugs in preclinical studies. There were comparable efficacies between all tested medications in both lactic acid-stimulated body stretching and -depressed feeding behaviors.
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Affiliation(s)
- Ahmad A Altarifi
- Department of Pharmacology, Faculty of Medicine, Jordan University of Science and Technology
| | - Bassel A Younis
- Department of Pharmacology, Faculty of Medicine, Jordan University of Science and Technology
| | - Khawla Q Nuseir
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology
| | - Arwa A Al-Mousa
- Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology
| | - Ahmad K Qaoud
- Department of Anesthesia and Recovery, Faculty of Medicine, Jordan University of Science and Technology, Irbid
| | - Mohammad I Alsalem
- Department of Anatomy and Histology, School of Medicine, The University of Jordan, Amman, Jordan
| | - John K Neubert
- Department of Orthodontics, College of Dentistry, University of Florida, Gainesville, Florida, USA
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Lee AS, Tiwari S, Bishop I, Matossian V, Romaneschi N, Miyazaki T, VanderVeen L, Zalevsky J, DeFea K, Cahill CM, Walwyn WM. In vivo and in vitro Characterization of a Partial Mu Opioid Receptor Agonist, NKTR-181, Supports Future Therapeutic Development. FRONTIERS IN PAIN RESEARCH 2021; 2:695962. [PMID: 35295409 PMCID: PMC8915576 DOI: 10.3389/fpain.2021.695962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/15/2021] [Indexed: 11/13/2022] Open
Abstract
Mu opioid receptor (MOPr) agonists are well-known and frequently used clinical analgesics but are also rewarding due to their highly addictive and often abusive properties. This may lead to opioid use disorder (OUD) a disorder that effects millions of people worldwide. Therefore, novel compounds are urgently needed to treat OUD. As opioids are effective analgesics and OUD often occurs in conjunction with chronic pain, these novel compounds may be opioids, but they must have a low abuse liability. This could be mediated by diminishing or slowing blood-brain barrier transport, slowing target receptor binding kinetics, and showing a long half-life. NKTR-181 is a PEGylated oxycodol and a MOPr agonist that has slowed blood-brain barrier transport, a long half-life, and diminished likeability in clinical trials. In this study, we examined the signaling and behavioral profile of NKTR-181 in comparison with oxycodone to determine whether further therapeutic development of this compound may be warranted. For this preclinical study, we used a number of in vitro and in vivo assays. The signaling profile of NKTR-181 was determined by the electrophysiological assessment of MOPr-Ca2+ channel inhibition in the nociceptive neurons of rodent dorsal root ganglia. Heterologous cell-based assays were used to assess biased agonism and receptor trafficking. Different rodent behavioral models were used to define the NKTR-181-induced relief of effective and reflexive nociception and drug-seeking behavior as assessed by an intravenous self-administration (IVSA) of NKTR-181. We found that NKTR-181 and oxycodone are partial agonists in G-protein signaling and Ca2+ channel inhibition assays and promote limited MOPr desensitization. However, NKTR-181 inhibits Ca2+ channels by a different mechanism than oxycodone and induces a different pattern of arrestin recruitment. In addition, NKTR-181 has a slower receptor on-rate and a slower rate of Ca2+ channel coupling than oxycodone. This signaling profile is coupled with a slower onset of antinociception and limited drug-seeking behavior in comparison with oxycodone. Together with its known long half-life and slow blood-brain barrier transport, these data suggest that NKTR-181 could be further studied as a pharmacotherapeutic treatment modality for OUD.
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Affiliation(s)
- Alex S. Lee
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Suchi Tiwari
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Isabel Bishop
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Vartan Matossian
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | - Nicole Romaneschi
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
| | | | | | | | - Kathryn DeFea
- KiloDalton Consulting, Orinda, CA, United States
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Catherine M. Cahill
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Shirley & Stefen Hatos Center for Neuropharmacology, University of California, Los Angeles, Los Angeles, CA, United States
- Jane & Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, United States
| | - Wendy M. Walwyn
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Shirley & Stefen Hatos Center for Neuropharmacology, University of California, Los Angeles, Los Angeles, CA, United States
- Jane & Terry Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, United States
- *Correspondence: Wendy M. Walwyn
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Kibaly C, Alderete JA, Liu SH, Nasef HS, Law PY, Evans CJ, Cahill CM. Oxycodone in the Opioid Epidemic: High 'Liking', 'Wanting', and Abuse Liability. Cell Mol Neurobiol 2021; 41:899-926. [PMID: 33245509 PMCID: PMC8155122 DOI: 10.1007/s10571-020-01013-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/17/2020] [Indexed: 12/13/2022]
Abstract
It is estimated that nearly a third of people who abuse drugs started with prescription opioid medicines. Approximately, 11.5 million Americans used prescription drugs recreationally in 2016, and in 2018, 46,802 Americans died as the result of an opioid overdose, including prescription opioids, heroin, and illicitly manufactured fentanyl (National Institutes on Drug Abuse (2020) Opioid Overdose Crisis. https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis . Accessed 06 June 2020). Yet physicians will continue to prescribe oral opioids for moderate-to-severe pain in the absence of alternative therapeutics, underscoring the importance in understanding how drug choice can influence detrimental outcomes. One of the opioid prescription medications that led to this crisis is oxycodone, where misuse of this drug has been rampant. Being one of the most highly prescribed opioid medications for treating moderate-to-severe pain as reflected in the skyrocketed increase in retail sales of 866% between 1997 and 2007, oxycodone was initially suggested to be less addictive than morphine. The false-claimed non-addictive formulation of oxycodone, OxyContin, further contributed to the opioid crisis. Abuse was often carried out by crushing the pills for immediate burst release, typically by nasal insufflation, or by liquefying the pills for intravenous injection. Here, we review oxycodone pharmacology and abuse liability as well as present the hypothesis that oxycodone may exhibit a unique pharmacology that contributes to its high likability and abuse susceptibility. We will discuss various mechanisms that likely contribute to the high abuse rate of oxycodone including clinical drug likability, pharmacokinetics, pharmacodynamics, differences in its actions within mesolimbic reward circuity compared to other opioids, and the possibility of differential molecular and cellular receptor interactions that contribute to its selective effects. We will also discuss marketing strategies and drug difference that likely contributes to the oxycodone opioid use disorders and addiction.
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Affiliation(s)
- Cherkaouia Kibaly
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA.
| | - Jacob A Alderete
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Steven H Liu
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Hazem S Nasef
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Ping-Yee Law
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Christopher J Evans
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA
| | - Catherine M Cahill
- Department of Psychiatry and Biobehavioral Sciences, Jane & Terry Semel Institute for Neuroscience and Human Behavior, Shirley and Stefan Hatos Center for Neuropharmacology, University of California, Los Angeles, CA, USA.
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Understanding Opioid Actions, Pain and Analgesia: A Tribute to Dr. Gavril Pasternak. Cell Mol Neurobiol 2021; 41:827-834. [PMID: 33978862 DOI: 10.1007/s10571-021-01097-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
This special issue is a tribute to our mentor, colleague and friend, Gavril W. Pasternak, MD, PhD. Homage to the breadth and depth of his work (~ 450 publications) over a 40 career in pharmacology and medicine cannot be captured fully in one special issue, but the 22 papers collected herein represent seven of the topics near and dear to Gav's heart, and the colleagues, friends and mentees who held him near to theirs. The seven themes include: (1) sites and mechanisms of opioid actions in vivo; (2) development of novel analgesic agents; (3) opioid tolerance, withdrawal and addiction: mechanisms and treatment; (4) opioid receptor splice variants; (5) novel research tools and approaches; (6) receptor signaling and crosstalk in vitro; and (7) mentorship. This introduction to the issue summarizes contributions and includes formal and personal remembrances of Gav that illustrate his personality, warmth, and dedication to making a difference in patient care and people's lives.
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