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El Daibani A, Madasu MK, Al-Hasani R, Che T. Limitations and potential of κOR biased agonists for pain and itch management. Neuropharmacology 2024; 258:110061. [PMID: 38960136 DOI: 10.1016/j.neuropharm.2024.110061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 06/20/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024]
Abstract
The concept of ligand bias is based on the premise that different agonists can elicit distinct responses by selectively activating the same receptor. These responses often determine whether an agonist has therapeutic or undesirable effects. Therefore, it would be highly advantageous to have agonists that specifically trigger the therapeutic response. The last two decades have seen a growing trend towards the consideration of ligand bias in the development of ligands to target the κ-opioid receptor (κOR). Most of these ligands selectively favor G-protein signaling over β-arrestin signaling to potentially provide effective pain and itch relief without adverse side effects associated with κOR activation. Importantly, the specific role of β-arrestin 2 in mediating κOR agonist-induced side effects remains unknown, and similarly the therapeutic and side-effect profiles of G-protein-biased κOR agonists have not been established. Furthermore, some drugs previously labeled as G-protein-biased may not exhibit true bias but may instead be either low-intrinsic-efficacy or partial agonists. In this review, we discuss the established methods to test ligand bias, their limitations in measuring bias factors for κOR agonists, as well as recommend the consideration of other systematic factors to correlate the degree of bias signaling and pharmacological effects. This article is part of the Special Issue on "Ligand Bias".
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Affiliation(s)
- Amal El Daibani
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Manish K Madasu
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Ream Al-Hasani
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
| | - Tao Che
- Center for Clinical Pharmacology, Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
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2
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Blaine AT, Miao Y, Yuan J, Palant S, Liu RJ, Zhang ZY, van Rijn RM. Exploration of beta-arrestin isoform signaling pathways in delta opioid receptor agonist-induced convulsions. Front Pharmacol 2022; 13:914651. [PMID: 36059958 PMCID: PMC9428791 DOI: 10.3389/fphar.2022.914651] [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: 04/07/2022] [Accepted: 07/13/2022] [Indexed: 11/17/2022] Open
Abstract
The δ-opioid receptor (δOR) has been considered as a therapeutic target in multiple neurological and neuropsychiatric disorders particularly as δOR agonists are deemed safer alternatives relative to the more abuse-liable µ-opioid receptor drugs. Clinical development of δOR agonists, however, has been challenging in part due to the seizure-inducing effects of certain δOR agonists. Especially agonists that resemble the δOR-selective agonist SNC80 have well-established convulsive activity. Close inspection suggests that many of those seizurogenic δOR agonists efficaciously recruit β-arrestin, yet surprisingly, SNC80 displays enhanced seizure activity in β-arrestin 1 knockout mice. This finding led us to hypothesize that perhaps β-arrestin 1 is protective against, whereas β-arrestin 2 is detrimental for δOR-agonist-induced seizures. To investigate our hypothesis, we characterized three different δOR agonists (SNC80, ADL5859, ARM390) in cellular assays and in vivo in wild-type and β-arrestin 1 and β-arrestin 2 knockout mice for seizure activity. We also investigated downstream kinases associated with β-arrestin-dependent signal transduction. We discovered that δOR agonist-induced seizure activity strongly and positively correlates with β-arrestin 2 efficacy for the agonist, but that indirect inhibition of ERK activation using the MEK inhibitor SL327 did not inhibit seizure potency and duration. Inhibition of the PI3K/AKT/mTOR signaling with honokiol but not PQR530, attenuated SNC80 seizure duration in β-arrestin 1 knockout, but honokiol did not reduce SNC80-induced seizures in wild-type mice. Ultimately, our results indicate that β-arrestin 2 is correlated with δOR agonist-induced seizure intensity, but that global β-arrestin 1 knockout mice are a poor model system to investigate their mechanism of action.
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Affiliation(s)
- Arryn T. Blaine
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
- Purdue Interdisciplinary Life Sciences Graduate Program, West Lafayette, IN, United States
| | - Yiming Miao
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Jinling Yuan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Sophia Palant
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Rebecca J. Liu
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Drug Discovery, West Lafayette, IN, United States
- Purdue University Cancer Center, West Lafayette, IN, United States
| | - Richard. M. van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
- Purdue Institute for Drug Discovery, West Lafayette, IN, United States
- Purdue University Cancer Center, West Lafayette, IN, United States
- Purdue Institute for Integrative Neuroscience, West Lafayette, IN, United States
- *Correspondence: Richard. M. van Rijn,
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3
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Phenotype Characterization of a Mice Genetic Model of Absolute Blindness. Int J Mol Sci 2022; 23:ijms23158152. [PMID: 35897728 PMCID: PMC9331777 DOI: 10.3390/ijms23158152] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 11/17/2022] Open
Abstract
Recent technological development requires new approaches to address the problem of blindness. Such approaches need to be able to ensure that no cells with photosensitive capability remain in the retina. The presented model, Opn4−/− × Pde6brd10/rd10 (O×Rd) double mutant murine, is a combination of a mutation in the Pde6b gene (photoreceptor degeneration) together with a deletion of the Opn4 gene (responsible for the expression of melanopsin in the intrinsically photosensitive retinal ganglion cells). This model has been characterized and compared with those of WT mice and murine animal models displaying both mutations separately. A total loss of pupillary reflex was observed. Likewise, behavioral tests demonstrated loss of rejection to illuminated spaces and a complete decrease in visual acuity (optomotor test). Functional recordings showed an absolute disappearance of various wave components of the full-field and pattern electroretinogram (fERG, pERG). Likewise, visual evoked potential (VEP) could not be recorded. Immunohistochemical staining showed marked degeneration of the outer retinal layers and the absence of melanopsin staining. The combination of both mutations has generated an animal model that does not show any photosensitive element in its retina. This model is a potential tool for the study of new ophthalmological approaches such as optosensitive agents.
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4
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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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5
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Karst H, den Boon FS, Vervoort N, Adrian M, Kapitein LC, Joëls M. Non-genomic steroid signaling through the mineralocorticoid receptor: Involvement of a membrane-associated receptor? Mol Cell Endocrinol 2022; 541:111501. [PMID: 34740745 DOI: 10.1016/j.mce.2021.111501] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 10/05/2021] [Accepted: 10/27/2021] [Indexed: 12/25/2022]
Abstract
Corticosteroid receptors in the mammalian brain mediate genomic as well as non-genomic actions. Although receptors mediating genomic actions were already cloned 35 years ago, it remains unclear whether the same molecules are responsible for the non-genomic actions or that the latter involve a separate class of receptors. Here we focus on one type of corticosteroid receptors, i.e. the mineralocorticoid receptor (MR). We summarize some of the known properties and the current insight in the localization of the MR in peripheral cells and neurons, especially in relation to non-genomic signaling. Previous studies from our own and other labs provided evidence that MRs mediating non-genomic actions are identical to the ones involved in genomic signaling, but may be translocated to the plasma cell membrane instead of the nucleus. With fixed cell imaging and live cell imaging techniques we tried to visualize these presumed membrane-associated MRs, using antibodies or overexpression of MR-GFP in COS7 and hippocampal cultured neurons. Despite the physiological evidence for MR location in or close to the cell membrane, we could not convincingly visualize membrane localization of endogenous MRs or GFP-MR molecules. However, we did find punctae of labeled antibodies intracellularly, which might indicate transactivating spots of MR near the membrane. We also found some evidence for trafficking of MR via beta-arrestins. In beta-arrestin knockout mice, we didn't observe metaplasticity in the basolateral amygdala anymore, indicating that internalization of MRs could play a role during corticosterone activation. Furthermore, we speculate that membrane-associated MRs could act indirectly via activating other membrane located structures like e.g. GPER and/or receptor tyrosine kinases.
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Affiliation(s)
- Henk Karst
- Dept Translational Neuroscience, University Medical Center Utrecht, Utrecht University, the Netherlands.
| | - Femke S den Boon
- Dept Translational Neuroscience, University Medical Center Utrecht, Utrecht University, the Netherlands
| | - Niek Vervoort
- University Utrecht, Faculty of Science, Division of Cell Biology, Utrecht, the Netherlands
| | - Max Adrian
- University Utrecht, Faculty of Science, Division of Cell Biology, Utrecht, the Netherlands
| | - Lukas C Kapitein
- University Utrecht, Faculty of Science, Division of Cell Biology, Utrecht, the Netherlands
| | - Marian Joëls
- Dept Translational Neuroscience, University Medical Center Utrecht, Utrecht University, the Netherlands; University Medical Center Groningen, University of Groningen, the Netherlands
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6
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Ko MJ, Chiang T, Mukadam AA, Mulia GE, Gutridge AM, Lin A, Chester JA, van Rijn RM. β-Arrestin-dependent ERK signaling reduces anxiety-like and conditioned fear-related behaviors in mice. Sci Signal 2021; 14:14/694/eaba0245. [PMID: 34344831 DOI: 10.1126/scisignal.aba0245] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
G protein-coupled receptors (GPCRs) are implicated in the regulation of fear and anxiety. GPCR signaling involves canonical G protein pathways but can also engage downstream kinases and effectors through scaffolding interactions mediated by β-arrestin. Here, we investigated whether β-arrestin signaling regulates anxiety-like and fear-related behavior in mice in response to activation of the GPCR δ-opioid receptor (δOR or DOR). Administration of β-arrestin-biased δOR agonists to male C57BL/6 mice revealed β-arrestin 2-dependent activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the dorsal hippocampus and amygdala and β-arrestin 1-dependent activation of ERK1/2 in the nucleus accumbens. In mice, β-arrestin-biased agonist treatment was associated with reduced anxiety-like and fear-related behaviors, with some overlapping and isoform-specific input. In contrast, applying a G protein-biased δOR agonist decreased ERK1/2 activity in all three regions as well as the dorsal striatum and was associated with increased fear-related behavior without effects on baseline anxiety. Our results indicate a complex picture of δOR neuromodulation in which β-arrestin 1- and 2-dependent ERK signaling in specific brain subregions suppresses behaviors associated with anxiety and fear and opposes the effects of G protein-biased signaling. Overall, our findings highlight the importance of noncanonical β-arrestin-dependent GPCR signaling in the regulation of these interrelated emotions.
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Affiliation(s)
- Mee Jung Ko
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA.,Purdue Institute for Integrative Neuroscience, West Lafayette, IN 47907, USA.,Purdue Interdisciplinary Life Sciences Graduate Program, West Lafayette, IN 47907, USA
| | - Terrance Chiang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Arbaaz A Mukadam
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA.,Department of Psychological Sciences, College of Health and Human Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Grace E Mulia
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA.,Purdue Interdisciplinary Life Sciences Graduate Program, West Lafayette, IN 47907, USA
| | - Anna M Gutridge
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA.,Purdue Institute for Integrative Neuroscience, West Lafayette, IN 47907, USA
| | - Angel Lin
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Julia A Chester
- Purdue Institute for Integrative Neuroscience, West Lafayette, IN 47907, USA.,Purdue Interdisciplinary Life Sciences Graduate Program, West Lafayette, IN 47907, USA.,Department of Psychological Sciences, College of Health and Human Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA. .,Purdue Institute for Integrative Neuroscience, West Lafayette, IN 47907, USA.,Purdue Interdisciplinary Life Sciences Graduate Program, West Lafayette, IN 47907, USA.,Purdue Institute for Drug Discovery, West Lafayette, IN 47907, USA
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7
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Mahmoodkhani M, Amini M, Derafshpour L, Ghasemi M, Mehranfard N. Negative relationship between brain α 1A-AR neurotransmission and βArr2 levels in anxious adolescent rats subjected to early life stress. Exp Brain Res 2020; 238:2833-2844. [PMID: 33025031 DOI: 10.1007/s00221-020-05937-1] [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: 07/02/2020] [Accepted: 09/27/2020] [Indexed: 01/06/2023]
Abstract
Early-life stress is correlated with the development of anxiety-related behavior in adolescence, but underlying mechanisms remain poorly known. The α1A-adrenergic receptor (AR) is linked to mood regulation and its function is assumed to be regulated by β-arrestins (βArrs) via desensitization and downregulation. Here, we investigated correlation between changes in α1A-AR and βArr2 levels in the prefrontal cortex (PFC) and hippocampus of adolescent and adult male rats subjected to maternal separation (MS) and their relationship with anxiety-like behavior in adolescence. MS was performed 3 h per day from postnatal days 2-11 and anxiety-like behavior was evaluated in the elevated plus-maze and open field tests. The protein levels were examined using western blot assay. MS decreased α1A-AR expression and increased βArr2 expression in both brain regions of adolescent rats, while induced reverse changes in adulthood. MS adolescent rats demonstrated higher anxiety-type behavior and lower activity in behavioral tests than controls. Decreased α1A-AR levels in MS adolescence strongly correlated with reduced time spent in the open field central area, consistent with increased anxiety-like behavior. An anxiety-like phenotype was mimicked by acute and chronic treatment of developing rats with prazosin, an α1A-AR antagonist, suggesting α1A-AR downregulation may facilitate anxiety behavior in MS adolescent rats. Together, our results indicate a negative correlation between α1A-AR neurotransmission and βArr2 levels in both adults and anxious-adolescent rats and suggest that increased βArr2 levels may contribute to posttranslational regulation of α1A-AR and modulation of anxiety-like behavior in adolescent rats. This may provide a path to develop more effective anxiolytic treatments.
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Affiliation(s)
- Maryam Mahmoodkhani
- Neurophysiology Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Mohammad Amini
- Neurophysiology Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Leila Derafshpour
- Neurophysiology Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Maedeh Ghasemi
- Department of Physiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Nasrin Mehranfard
- Neurophysiology Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran.
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8
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Gutridge AM, Robins MT, Cassell RJ, Uprety R, Mores KL, Ko MJ, Pasternak GW, Majumdar S, van Rijn RM. G protein-biased kratom-alkaloids and synthetic carfentanil-amide opioids as potential treatments for alcohol use disorder. Br J Pharmacol 2020; 177:1497-1513. [PMID: 31705528 PMCID: PMC7060366 DOI: 10.1111/bph.14913] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/12/2019] [Accepted: 10/15/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE Mitragyna speciosa, more commonly known as kratom, is a plant that contains opioidergic alkaloids but is unregulated in most countries. Kratom is used in the self-medication of chronic pain and to reduce illicit and prescription opioid dependence. Kratom may be less dangerous than typical opioids because of the stronger preference of kratom alkaloids to induce receptor interaction with G proteins over β-arrestin proteins. We hypothesized that kratom (alkaloids) can also reduce alcohol intake. EXPERIMENTAL APPROACH We pharmacologically characterized kratom extracts, kratom alkaloids (mitragynine, 7-hydroxymitragynine, paynantheine, and speciogynine) and synthetic carfentanil-amide opioids for their ability to interact with G proteins and β-arrestin at μ, δ, and κ opioid receptors in vitro. We used C57BL/6 mice to assess to which degree these opioids could reduce alcohol intake and whether they had rewarding properties. KEY RESULTS Kratom alkaloids were strongly G protein-biased at all three opioid receptors and reduced alcohol intake, but kratom and 7-hydroxymitragynine were rewarding. Several results indicated a key role for δ opioid receptors, including that the synthetic carfentanil-amide opioid MP102-a G protein-biased agonist with modest selectivity for δ opioid receptors-reduced alcohol intake, whereas the G protein-biased μ opioid agonist TRV130 did not. CONCLUSION AND IMPLICATIONS Our results suggest that kratom extracts can decrease alcohol intake but still carry significant risk upon prolonged use. Development of more δ opioid-selective synthetic opioids may provide a safer option than kratom to treat alcohol use disorder with fewer side effects.
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Affiliation(s)
- Anna M. Gutridge
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
| | - Meridith T. Robins
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
| | - Robert J. Cassell
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
| | - Rajendra Uprety
- Department of Neurology and Molecular PharmacologyMemorial Sloan Kettering Cancer CenterNew YorkNew York
| | - Kendall L. Mores
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
| | - Mee Jung Ko
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
- Purdue Interdisciplinary Life Sciences Graduate ProgramPurdue UniversityWest LafayetteIndiana
| | - Gavril W. Pasternak
- Department of Neurology and Molecular PharmacologyMemorial Sloan Kettering Cancer CenterNew YorkNew York
| | - Susruta Majumdar
- Department of Neurology and Molecular PharmacologyMemorial Sloan Kettering Cancer CenterNew YorkNew York
- Center for Clinical PharmacologySt. Louis College of Pharmacy and Washington University School of MedicineSt. LouisMissouri
| | - Richard M. van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, College of PharmacyPurdue UniversityWest LafayetteIndiana
- Purdue Institute for Drug DiscoveryPurdue UniversityWest LafayetteIndiana
- Purdue Institute for Integrative NeurosciencePurdue UniversityWest LafayetteIndiana
- Purdue Interdisciplinary Life Sciences Graduate ProgramPurdue UniversityWest LafayetteIndiana
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9
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Mores KL, Cassell RJ, van Rijn RM. Arrestin recruitment and signaling by G protein-coupled receptor heteromers. Neuropharmacology 2018; 152:15-21. [PMID: 30419245 DOI: 10.1016/j.neuropharm.2018.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/28/2018] [Accepted: 11/08/2018] [Indexed: 12/12/2022]
Abstract
G protein-coupled receptors (GPCR) have a long history of being considered a prime target for drug development to treat a plethora of diseases and disorders. In fact in 1827, the first approved therapeutic in the United States was morphine, a drug that targets a GPCR, namely the mu opioid receptor. However, with the rise in biologics over the last two decades, the market share of small molecules targeting GPCRs has declined. Still, two phenomena concerning GPCR pharmacology, specifically heteromerization and biased signaling, have bolstered new interests in this particular class of drug targets. Heteromerization, the process by which two distinct GPCRs come together to form a unique signaling complex, has been demonstrated between many different GPCRs and has spurred efforts to discover heteromer selective drugs. Additionally, the discovery of biased signaling, a concept by which a GPCR can transduce intracellular signaling by favoring a specific pathway (e.g. G-protein) over another pathway (e.g. arrestin), has led to the development of signal-biased drugs with potentially fewer side effects. Our goal for this review is to highlight studies that have investigated the interplay of these two phenomena by providing an overview of the current literature describing instances where GPCR heteromers have distinct arrestin recruitment profiles when compared to the individual GPCRs, with a focus on those GPCRs expressed in the central nervous system. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.
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Affiliation(s)
- Kendall L Mores
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, United States
| | - Robert J Cassell
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, United States
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, United States; Purdue Institute for Drug Discovery, United States; Purdue Institute for Integrative Neuroscience, West Lafayette, IN, 47907, United States.
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10
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Robins MT, Chiang T, Mores KL, Alongkronrusmee D, van Rijn RM. Critical Role for G i/o-Protein Activity in the Dorsal Striatum in the Reduction of Voluntary Alcohol Intake in C57Bl/6 Mice. Front Psychiatry 2018; 9:112. [PMID: 29686629 PMCID: PMC5900748 DOI: 10.3389/fpsyt.2018.00112] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/19/2018] [Indexed: 12/21/2022] Open
Abstract
The transition from non-dependent alcohol use to alcohol dependence involves increased activity of the dorsal striatum. Interestingly, the dorsal striatum expresses a large number of inhibitory G-protein-coupled receptors (GPCRs), which when activated may inhibit alcohol-induced increased activity and can decrease alcohol consumption. Here, we explore the hypothesis that dorsal striatal Gi/o-protein activation is sufficient to reduce voluntary alcohol intake. Using a voluntary, limited-access, two-bottle choice, drink-in-the-dark model of alcohol (10%) consumption, we validated the importance of Gi/o signaling in this region by locally expressing neuron-specific, adeno-associated-virus encoded Gi/o-coupled muscarinic M4 designer receptors exclusively activated by designer drugs (DREADD) in the dorsal striatum and observed a decrease in alcohol intake upon DREADD activation. We validated our findings by activating Gi/o-coupled delta-opioid receptors (DORs), which are natively expressed in the dorsal striatum, using either a G-protein biased agonist or a β-arrestin-biased agonist. Local infusion of TAN-67, an in vitro-determined Gi/o-protein biased DOR agonist, decreased voluntary alcohol intake in wild-type and β-arrestin-2 knockout (KO) mice. SNC80, a β-arrestin-2 biased DOR agonist, increased alcohol intake in wild-type mice; however, SNC80 decreased alcohol intake in β-arrestin-2 KO mice, thus resulting in a behavioral outcome generally observed for Gi/o-biased agonists and suggesting that β-arrestin recruitment is required for SNC80-increased alcohol intake. Overall, these results suggest that activation Gi/o-coupled GPCRs expressed in the dorsal striatum, such as the DOR, by G-protein biased agonists may be a potential strategy to decrease voluntary alcohol consumption and β-arrestin recruitment is to be avoided.
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Affiliation(s)
- Meridith T Robins
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue University Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Terrance Chiang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue University Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Kendall L Mores
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States
| | - Doungkamol Alongkronrusmee
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue University Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
| | - Richard M van Rijn
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN, United States.,Purdue University Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States
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