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Singh K, Yadav A, Khan S, Shukla A, Alam M, Verma AK, Tiwari N, Khan F, Yadav PN, Dev K. Baicalein isolated from Oroxylum indicum acts as a potent µ- and κ-opioid receptor antagonist agent via the reversal of agonist-mediated cAMP inhibition. Nat Prod Res 2024:1-9. [PMID: 39205489 DOI: 10.1080/14786419.2024.2396452] [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: 01/09/2024] [Revised: 08/05/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024]
Abstract
The opioid receptors play a pivotal role in the treatment of several neuropsychiatric and neurological disorders. Oroxylum indicum (L.) Kurtz is a very important medicinal plant with several therapeutic applications. It is a main constituent of the Ayurvedic formulation 'Dashmool' used for multifaceted disorders by the Indians. However, the constituents of this plant in neurological conditions have not been well studied. Here, we performed activity-guided isolation of compounds for opioid receptor modulator activity. In the study, we found that the isolated compound baicalein (3) has shown the most potent and competitive antagonistic activity at 20 mg/kg dose in vivo experiments. The acute dose of 3 (20 mg/kg) and pan opioid receptor antagonist naloxone (20 mg/kg) block the morphine-induced antinociception and the paw withdrawal latency decreases up to 8.3 s and 9.6 s, respectively. The in silico studies also support our in vitro data that compound 3 binds with MOR and KOR.
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Affiliation(s)
- Kishan Singh
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
- Academy of Innovative and Scientific Research (AcSIR), Ghaziabad, India
| | - Anubhav Yadav
- Academy of Innovative and Scientific Research (AcSIR), Ghaziabad, India
- Neuroscience & Ageing Biology Division, CSIR-Central Drug Research Institute, Lucknow, India
| | - Sana Khan
- Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Arti Shukla
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Maksood Alam
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | | | - Neerja Tiwari
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Feroz Khan
- Academy of Innovative and Scientific Research (AcSIR), Ghaziabad, India
- Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Prem Narayan Yadav
- Academy of Innovative and Scientific Research (AcSIR), Ghaziabad, India
- Neuroscience & Ageing Biology Division, CSIR-Central Drug Research Institute, Lucknow, India
| | - Kapil Dev
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
- Academy of Innovative and Scientific Research (AcSIR), Ghaziabad, India
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2
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Schaffer J, Fogelman N, Seo D, Sinha R. Chronic pain, chronic stress and substance use: overlapping mechanisms and implications. FRONTIERS IN PAIN RESEARCH 2023; 4:1145934. [PMID: 37415830 PMCID: PMC10320206 DOI: 10.3389/fpain.2023.1145934] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 06/05/2023] [Indexed: 07/08/2023] Open
Abstract
Chronic pain is among the most common reasons adults in the U.S. seek medical care. Despite chronic pain's substantial impact on individuals' physical, emotional, and financial wellness, the biologic underpinnings of chronic pain remain incompletely understood. Such deleterious impact on an individuals' wellness is also manifested in the substantial co-occurrence of chronic stress with chronic pain. However, whether chronic stress and adversity and related alcohol and substance misuse increases risk of developing chronic pain, and, if so, what the overlapping psychobiological processes are, is not well understood. Individuals suffering with chronic pain find alleviation through prescription opioids as well as non-prescribed cannabis, alcohol, and other drugs to control pain, and use of these substances have grown significantly. Substance misuse also increases experience of chronic stress. Thus, given the evidence showing a strong correlation between chronic stress and chronic pain, we aim to review and identify overlapping factors and processes. We first explore the predisposing factors and psychologic features common to both conditions. This is followed by examining the overlapping neural circuitry of pain and stress in order to trace a common pathophysiologic processes for the development of chronic pain and its link to substance use. Based on the previous literature and our own findings, we propose a critical role for ventromedial prefrontal cortex dysfunction, an overlapping brain area associated with the regulation of both pain and stress that is also affected by substance use, as key in the risk of developing chronic pain. Finally, we identify the need for future research in exploring the role of medial prefrontal circuits in chronic pain pathology. Critically, in order to alleviate the enormous burden of chronic pain without exacerbating the co-occurring substance misuse crisis, we emphasize the need to find better approaches to treat and prevent chronic pain.
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Affiliation(s)
| | | | | | - R. Sinha
- Department of Psychiatry and the Yale Stress Center, Yale University School of Medicine, New Haven, CT, United States
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3
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Johnson BN, Kumar A, Su Y, Singh S, Sai KKS, Nader SH, Li S, Reboussin BA, Huang Y, Deep G, Nader MA. PET imaging of kappa opioid receptors and receptor expression quantified in neuron-derived extracellular vesicles in socially housed female and male cynomolgus macaques. Neuropsychopharmacology 2023; 48:410-417. [PMID: 36100655 PMCID: PMC9751296 DOI: 10.1038/s41386-022-01444-9] [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: 05/13/2022] [Revised: 07/27/2022] [Accepted: 08/24/2022] [Indexed: 12/26/2022]
Abstract
Recent positron emission tomography (PET) studies of kappa opioid receptors (KOR) in humans reported significant relationships between KOR availability and social status, as well as cocaine choice. In monkey models, social status influences physiology, receptor pharmacology and behavior; these variables have been associated vulnerability to cocaine abuse. The present study utilized PET imaging to examine KOR availability in socially housed, cocaine-naïve female and male monkeys, and peripheral measures of KORs with neuron-derived extracellular vesicles (NDE). KOR availability was assessed in dominant and subordinate female and male cynomolgus macaques (N = 4/rank/sex), using PET imaging with the KOR selective agonist [11C]EKAP. In addition, NDE from the plasma of socially housed monkeys (N = 13/sex; N = 6-7/rank) were isolated by immunocapture method and analyzed for OPRK1 protein expression by ELISA. We found significant interactions between sex and social rank in KOR availability across 12 of 15 brain regions. This was driven by female data, in which KOR availability was significantly higher in subordinate monkeys compared with dominant monkeys; the opposite relationship was observed among males, but not statistically significant. No sex or rank differences were observed for NDE OPRK1 concentrations. In summary, the relationship between brain KOR availability and social rank was different in female and male monkeys. This was particularly true in female monkeys. We hypothesize that lower [11C]EKAP binding potentials were due to higher concentrations of circulating dynorphin, which is consistent with greater vulnerability in dominant compared with subordinate females. These findings suggest that the KOR is an important target for understanding the neurobiology associated with vulnerability to abused drugs and sex differences, and detectable in peripheral circulation.
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Affiliation(s)
- Bernard N Johnson
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
- Center for Addiction Research, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Ashish Kumar
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Yixin Su
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Sangeeta Singh
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Kiran Kumar Solingapuram Sai
- Center for Addiction Research, Wake Forest University School of Medicine, Winston-Salem, NC, USA
- Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Susan H Nader
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Songye Li
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Beth A Reboussin
- Department of Biostatistics and Data Sciences, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Gagan Deep
- Center for Addiction Research, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
| | - Michael A Nader
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
- Center for Addiction Research, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
- Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
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Ji MJ, Gao ZQ, Yang J, Cai JH, Li KX, Wang J, Zhang H, Zhou CH, Cao JL, Liu C. Dynorphin promotes stress-induced depressive behaviors by inhibiting ventral pallidal neurons in rats. Acta Physiol (Oxf) 2022; 236:e13882. [PMID: 36039689 DOI: 10.1111/apha.13882] [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] [Received: 03/27/2022] [Revised: 08/24/2022] [Accepted: 08/26/2022] [Indexed: 01/29/2023]
Abstract
AIM Endogenous dynorphin signaling via kappa opioid receptors (KORs) plays a key role in producing the depressive and aversive consequences of stress. We investigated the behavioral effects of the dynorphin/KOR system in the ventral pallidum (VP) and studied the underlying mechanisms. METHODS To investigate the effects of dynorphin on the VP, we conducted behavioral experiments after microinjection of drugs or shRNA and brain-slice electrophysiological recordings. Histological tracing and molecular biological experiments were used to identify the distribution of KORs and the possible sources of dynorphin projections to the VP. RESULTS An elevated dynorphin concentration and increased KOR activity were observed in the VP after acute stress. Infusion of dynorphin-A into the VP produced depressive-like phenotypes including anhedonia and despair and anxiety behaviors, but did not alter locomotor behavior. Mechanistically, dynorphin had an inhibitory effect on VP neurons-reducing their firing rate and inhibiting excitatory transmission-through direct activation of KORs and modulation of downstream G-protein-gated inwardly rectifying potassium (GIRK) channels and high-voltage gated calcium channels (VGCCs). Tracing revealed direct innervation of VP neurons by dynorphin-positive projections; potential sources of these dynorphinergic projections include the nucleus accumbens, amygdala, and hypothalamus. Blockade of dynorphin/KOR signaling in the VP by drugs or viral knock-down of KORs significantly reduced despair behavior in rats. CONCLUSIONS Endogenous dynorphinergic modulation of the VP plays a critical role in mediating depressive reactions to stress.
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Affiliation(s)
- Miao-Jin Ji
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Zhi-Qiang Gao
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Jiao Yang
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Ji-Heng Cai
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Ke-Xue Li
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
| | - Jie Wang
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Hongxing Zhang
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Cheng-Hua Zhou
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Jun-Li Cao
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
| | - Chao Liu
- 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, School of Anesthesiology, Xuzhou Medical University, Xuzhou, China
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5
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Shevick S, Freeman SM, Tong G, Russo RJ, Bohn LM, Shenvi RA. Asymmetric Syntheses of (+)- and (-)-Collybolide Enable Reevaluation of kappa-Opioid Receptor Agonism. ACS CENTRAL SCIENCE 2022; 8:948-954. [PMID: 35912357 PMCID: PMC9335922 DOI: 10.1021/acscentsci.2c00442] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The fungal metabolite collybolide has attracted attention as a non-nitrogenous, potent, and biased agonist of the kappa-opioid receptor (KOR). Here, we report a 10-step asymmetric synthesis of this complex sesquiterpene that enables facile access to either enantiomer. The synthesis relies on a diastereoselective α-benzoyloxylation to install the buried C6 benzoate and avoid irreversible translactonization of the congested, functionally dense core. Neither enantiomer, however, exhibited KOR agonism, indicating that collybolide has been mischaracterized as a KOR agonist. Given the pharmaceutical, medical, and societal interest in collybolide as a next-generation antipruritic and analgesic, this refutation of KOR activity has important ramifications for ongoing studies. Classification of collybolide as a new non-nitrogenous, KOR-selective, potent agonist with the same clinical potential as salvinorin A seems to have been premature.
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Affiliation(s)
- Sophia
L. Shevick
- Department
of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
- Skaggs
Graduate School of Chemical and Biological Sciences, Scripps Research, 10550
North Torrey Pines Road, La Jolla, California 92037, United States
| | - Stephan M. Freeman
- Department
of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
- Skaggs
Graduate School of Chemical and Biological Sciences, Scripps Research, 10550
North Torrey Pines Road, La Jolla, California 92037, United States
| | - Guanghu Tong
- Department
of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Robin J. Russo
- Department
of Molecular Medicine, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
- Skaggs
Graduate School of Chemical and Biological Sciences, Scripps Research, 130
Scripps Way, Jupiter, Florida 33458, United States
| | - Laura M. Bohn
- Department
of Molecular Medicine, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Ryan A. Shenvi
- Department
of Chemistry, Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Turan Yücel N, Evren AE, Kandemir Ü, Can ÖD. Antidepressant-like effect of tofisopam in mice: A behavioural, molecular docking and MD simulation study. J Psychopharmacol 2022; 36:819-835. [PMID: 35638175 DOI: 10.1177/02698811221095528] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Depression is a disease that affects millions of people worldwide, and the discovery and development of effective and safe antidepressant drugs is one of the important topics of psychopharmacology. OBJECTIVES In this study, it was aimed to investigate the antidepressant-like activity potential of tofisopam, an anxiolytic drug with 2,3-benzodiazepine structure, and to elucidate the pharmacological mechanisms mediating this effect. METHODS The antidepressant-like activity of tofisopam was investigated using tail suspension and modified forced swimming tests. Possible interactions of tofisopam with µ- and δ-opioid receptor subtypes were clarified by pharmacological antagonism, molecular docking and molecular dynamics simulation studies. RESULTS Tofisopam (50 and 100 mg/kg) significantly shortened the immobility time of mice in both the tail suspension and the modified forced swimming tests. The drug, at the same doses, prolonged the duration of swimming and climbing behaviours measured in modified forced swimming tests. A dosage of 25 mg/kg was ineffective. Mechanistic studies showed that the pretreatment with p-chlorophenylalanine methyl ester (serotonin synthesis inhibitor; 4 consecutive days, 100 mg/kg), α-methyl-para-tyrosine methyl ester (catecholamine synthesis inhibitor; 100 mg/kg), naloxonazine (selective µ-opioid receptor blocker, 7 mg/kg) and naltrindole (a selective δ-opioid receptor blocker, 0.99 mg/kg) abolished the anti-immobility effect induced by the 50 mg/kg dose of tofisopam in the tail suspension tests. Our in silico studies supported the behavioural findings that the antidepressant-like effect of tofisopam is mediated by μ- and δ-opioid receptors. CONCLUSION This study is the first to show that tofisopam has antidepressant-like activity mediated by the serotonergic, catecholaminergic and opioidergic systems.
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Affiliation(s)
- Nazlı Turan Yücel
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskişehir, Turkey
| | - Asaf Evrim Evren
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Anadolu University, Eskişehir, Turkey.,Pharmacy Services, Vocational School of Health Services, Bilecik Şeyh Edebali University, Bilecik, Turkey
| | - Ümmühan Kandemir
- Department of Pharmacology, Institute of Health Sciences, Anadolu University, Eskişehir, Turkey
| | - Özgür Devrim Can
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskişehir, Turkey
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Yang S, Xu K, Xu X, Zhu J, Jin Y, Liu Q, Xu R, Gu X, Liu Y, Huang Y, Ma Z. S-Ketamine Pretreatment Alleviates Anxiety-Like Behaviors and Mechanical Allodynia and Blocks the Pro-inflammatory Response in Striatum and Periaqueductal Gray From a Post-traumatic Stress Disorder Model. Front Behav Neurosci 2022; 16:848232. [PMID: 35493953 PMCID: PMC9047507 DOI: 10.3389/fnbeh.2022.848232] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/11/2022] [Indexed: 01/21/2023] Open
Abstract
This study aims to explore the regulatory effect of S-ketamine on the mechanical allodynia, anxiety-like behaviors and microglia activation in adult male rats exposed to an animal model of post-traumatic stress disorder (PTSD). The rat PTSD model was established by the exposure to single-prolonged stress (SPS), and 1 day later, rats were intraperitoneally injected with 5 mg/kg S-ketamine or normal saline, respectively. Paw withdrawal mechanical threshold was measured 2 days before, and 1, 3, 5, 7, 10, 14, 21 and 28 days after injection to assess mechanical allodynia in the SPS-exposed rats. For anxiety-like behaviors, the open field test and elevated plus maze test were performed at 7 and 14 days after S-ketamine treatment in the SPS-exposed rats, respectively. SPS-induced rats presented pronounced mechanical allodynia and anxiety-like behaviors, which were alleviated by S-ketamine treatment. After behavioral tests, rats were sacrificed for collecting the anterior cingulate cortex (ACC), prefrontal cortex (PFC), dorsal striatum, and periaqueductal gray (PAG). Protein levels of TNF-α, IL-1β, p-NF-κB, and NF-κB in brain regions were examined by Western blot. In addition, microglia activation in each brain region was determined by immunofluorescence staining of the microglia-specific biomarker Iba-1. Interestingly, pro-inflammatory cytokines were significantly upregulated in the dorsal striatum and PAG, rather than ACC and PFC. Activated microglia was observed in the dorsal striatum and PAG as well, and upregulated p-NF-κB was detected in the dorsal striatum. Inflammatory response, phosphorylation of NF-κB and microglia activation in certain brain regions were significantly alleviated by S-ketamine treatment. Collectively, S-ketamine is a promising drug in alleviating mechanical allodynia, anxiety-like behaviors, and pro-inflammatory responses in discrete brain regions in a model of PTSD.
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8
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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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