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Zheng H, Kim M, Kim C, Kim Y, Cho PS, Lim JY, Lee H, Yun HI, Choi J, Hwang SW. GnRH peripherally modulates nociceptor functions, exacerbating mechanical pain. Front Mol Neurosci 2024; 17:1160435. [PMID: 38783903 PMCID: PMC11111891 DOI: 10.3389/fnmol.2024.1160435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 04/22/2024] [Indexed: 05/25/2024] Open
Abstract
The function of peripheral nociceptors, the neurons that relay pain signals to the brain, are frequently tuned by local and systemic modulator substances. In this context, neurohormonal effects are emerging as an important modulatory mechanism, but many aspects remain to be elucidated. Here we report that gonadotropin-releasing hormone (GnRH), a brain-specific neurohormone, can aggravate pain by acting on nociceptors in mice. GnRH and GnRHR, the receptor for GnRH, are expressed in a nociceptor subpopulation. Administration of GnRH and its analogue, localized for selectively affecting the peripheral neurons, deteriorated mechanical pain, which was reproducible in neuropathic conditions. Nociceptor function was promoted by GnRH treatment in vitro, which appears to involve specific sensory transient receptor potential ion channels. These data suggest that peripheral GnRH can positively modulate nociceptor activities in its receptor-specific manner, contributing to pain exacerbation. Our study indicates that GnRH plays an important role in neurohormonal pain modulation via a peripheral mechanism.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Sun Wook Hwang
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, Republic of Korea
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Xu C, Wang Y, Ni H, Yao M, Cheng L, Lin X. The role of orphan G protein-coupled receptors in pain. Heliyon 2024; 10:e28818. [PMID: 38590871 PMCID: PMC11000026 DOI: 10.1016/j.heliyon.2024.e28818] [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: 10/26/2023] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/10/2024] Open
Abstract
G protein-coupled receptors (GPCRs), which form the largest family of membrane protein receptors in humans, are highly complex signaling systems with intricate structures and dynamic conformations and locations. Among these receptors, a specific subset is referred to as orphan GPCRs (oGPCRs) and has garnered significant interest in pain research due to their role in both central and peripheral nervous system function. The diversity of GPCR functions is attributed to multiple factors, including allosteric modulators, signaling bias, oligomerization, constitutive signaling, and compartmentalized signaling. This review primarily focuses on the recent advances in oGPCR research on pain mechanisms, discussing the role of specific oGPCRs including GPR34, GPR37, GPR65, GPR83, GPR84, GPR85, GPR132, GPR151, GPR160, GPR171, GPR177, and GPR183. The orphan receptors among these receptors associated with central nervous system diseases are also briefly described. Understanding the functions of these oGPCRs can contribute not only to a deeper understanding of pain mechanisms but also offer a reference for discovering new targets for pain treatment.
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Affiliation(s)
- Chengfei Xu
- Department of Anesthesiology, The Third People's Hospital of Bengbu, Bengbu, 233000, PR China
| | - Yahui Wang
- Department of Anesthesiology, The First Affiliated Hospital of Bengbu Medical University, Bengbu, 233000, PR China
| | - Huadong Ni
- Department of Anesthesiology and Pain Research Center, Affiliated Hospital of Jiaxing University, Jiaxing, 314000, PR China
| | - Ming Yao
- Department of Anesthesiology and Pain Research Center, Affiliated Hospital of Jiaxing University, Jiaxing, 314000, PR China
| | - Liang Cheng
- Department of Anesthesiology, The Third People's Hospital of Bengbu, Bengbu, 233000, PR China
| | - Xuewu Lin
- Department of Anesthesiology, The First Affiliated Hospital of Bengbu Medical University, Bengbu, 233000, PR China
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Kim C, Kim Y, Lim JY, Kim M, Zheng H, Kim M, Hwang SW. Pamoic acid-induced peripheral GPR35 activation improves pruritus and dermatitis. Br J Pharmacol 2023; 180:3059-3070. [PMID: 37501600 DOI: 10.1111/bph.16201] [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: 03/03/2022] [Revised: 07/12/2023] [Accepted: 07/16/2023] [Indexed: 07/29/2023] Open
Abstract
BACKGROUND AND PURPOSE Pruritic dermatitis is a disease with a considerable unmet need for treatment and appears to present with not only epidermal but also peripheral neuronal complications. Here, we propose a novel pharmacological modulation targeting both peripheral dorsal root ganglion (DRG) sensory neurons and skin keratinocytes. GPR35 is an orphan G-protein-coupled receptor expressed in DRG neurons and has been predicted to downregulate neuronal excitability when activated. Modulator information is currently increasing for GPR35, and pamoic acid (PA), a salt-forming agent for drugs, has been shown to be an activator solely specific for GPR35. Here, we investigated its effects on dermatitic pathology. EXPERIMENTAL APPROACH We confirmed GPR35 expression in peripheral neurons and tissues. The effect of PA treatment was pharmacologically evaluated in cultured cells in vitro and in in vivo animal models for acute and chronic pruritus. KEY RESULTS Local PA application mitigated acute non-histaminergic itch and, consistently, obstructed DRG neuronal responses. Keratinocyte fragmentation under dermatitic simulation was also dampened following PA incubation. Chronic pruritus in 1-chloro-2,4-dinitrobenzene and psoriasis models were also moderately but significantly reversed by the repeated applications of PA. Dermatitic scores in the 1-chloro-2,4-dinitrobenzene and psoriatic models were also improved by its application, indicating that it is beneficial for mitigating disease pathology. CONCLUSION AND IMPLICATIONS Our findings suggest that pamoic acid activation of peripheral GPR35 can contribute to the improvement of pruritus and its associated diseases.
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Affiliation(s)
- Chaeeun Kim
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Yerin Kim
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Ji Yeon Lim
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Minseok Kim
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Haiyan Zheng
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Miri Kim
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
| | - Sun Wook Hwang
- Department of Biomedical Sciences and Department of Physiology, College of Medicine, Korea University, Seoul, Korea
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McDermott MV, Ram A, Mattoon MT, Haderlie EE, Raddatz MC, Thomason MK, Bobeck EN. A small molecule ligand for the novel pain target, GPR171, produces minimal reward in mice. Pharmacol Biochem Behav 2023; 224:173543. [PMID: 36933620 DOI: 10.1016/j.pbb.2023.173543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 03/19/2023]
Abstract
ProSAAS is one of the most abundant proteins in the brain and is processed into several smaller peptides. One of which, BigLEN, is an endogenous ligand for the G protein-coupled receptor, GPR171. Recent work in rodent models has shown that a small-molecule ligand for GPR171, MS15203, increases morphine antinociception and is effective in lessening chronic pain. While these studies provide evidence for GPR171 as a possible pain target, its abuse liability has not yet been assessed and was evaluated in the current study. We first mapped the distribution of GPR171 and ProSAAS throughout the reward circuit of the brain using immunohistochemistry and showed that GPR171 and ProSAAS are localized in the hippocampus, basolateral amygdala, nucleus accumbens, prefrontal cortex. In the major dopaminergic structure, the ventral tegmental area (VTA), GPR171 appeared to be primarily localized in dopamine neurons while ProSAAS is outside of dopamine neurons. Next, MS15203 was administered to mice with or without morphine, and VTA slices were stained for the immediate early gene c-Fos as a marker of neuronal activation. Quantification of c-Fos-positive cells revealed no statistical difference between MS15203 and saline, suggesting that MS15203 does not increase VTA activation and dopamine release. The results of a conditioned place preference experiment showed that treatment with MS15203 produced no place preference indicating a lack of reward-related behavior. Taken together this data provides evidence that the novel pain therapeutic, MS15203, has minimal reward liability. Therefore, GPR171 deserves further exploration as a pain target. SIGNIFICANCE STATEMENT: MS15203, a drug that activates the receptor GPR171, was previously shown to increase morphine analgesia. The authors use in vivo and histological techniques to show that it fails to activate the rodent reward circuitry, providing support for the continued exploration of MS15203 as a novel pain drug, and GPR171 a novel pain target.
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Affiliation(s)
- Max V McDermott
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America; Interdisciplinary Neuroscience Program, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Akila Ram
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Matthew T Mattoon
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Emmaline E Haderlie
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Megan C Raddatz
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America; Interdisciplinary Neuroscience Program, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Madi K Thomason
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America
| | - Erin N Bobeck
- Dept. of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America; Interdisciplinary Neuroscience Program, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, United States of America.
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Kim Y, Kim C, Lee H, Kim M, Zheng H, Lim JY, Yun HI, Jeon M, Choi J, Hwang SW. Gpr83 Tunes Nociceptor Function, Controlling Pain. Neurotherapeutics 2023; 20:325-337. [PMID: 36352334 PMCID: PMC10119354 DOI: 10.1007/s13311-022-01327-3] [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] [Accepted: 10/27/2022] [Indexed: 11/10/2022] Open
Abstract
The function of peripheral nociceptors is frequently tuned by the action of G protein-coupled receptors (GPRs) that are expressed in them, which contribute to pain alteration. Expanding new information on such GPRs and predicting their potential outcomes can help to construct new analgesic strategies based on their modulations. In this context, we attempted to present a new GPR not yet acknowledged for its pain association. Gpr83 exhibits relatively high expressions in the peripheral nervous system compared to other tissues when we mined and reconstructed Gene Expression Omnibus (GEO) metadata, which we confirmed using immunohistochemistry on murine dorsal root ganglia (DRG). When Gpr83 expression was silenced in DRG, neuronal and behavioral nociception were all downregulated. Pathologic pain in hind paw inflammation and chemotherapy-induced peripheral neuropathy were also alleviated by this Gpr83 knockdown. Dependent on exposure time, the application of a known endogenous Gpr83 ligand PEN showed differential effects on nociceptor responses in vitro. Localized PEN administration mitigated pain in vivo, probably following Gq/11-involved GPR downregulation caused by the relatively constant exposure. Collectively, this study suggests that Gpr83 action contributes to the tuning of peripheral pain sensitivity and thus indicates that Gpr83 can be among the potential GPR targets for pain modulation.
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Affiliation(s)
- Yerin Kim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Chaeeun Kim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Hojin Lee
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Minseok Kim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Haiyan Zheng
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Ji Yeon Lim
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Hye-In Yun
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Minji Jeon
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Jungmin Choi
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea
| | - Sun Wook Hwang
- Department of Biomedical Sciences, Korea University College of Medicine, Seoul, 02841, Korea.
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Afrose L, McDermott MV, Bhuiyan AI, Pathak SK, Bobeck EN. GPR171 activation regulates morphine tolerance but not withdrawal in a test-dependent manner in mice. Behav Pharmacol 2022; 33:442-451. [PMID: 35942845 PMCID: PMC9477863 DOI: 10.1097/fbp.0000000000000692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/07/2022] [Indexed: 11/26/2022]
Abstract
A newly deorphanized G protein-coupled receptor, GPR171, is found to be highly expressed within the periaqueductal gray, a pain-modulating region in the brain. Our recent research has shown that a GPR171 agonist increases morphine antinociception in male mice and opioid signaling in vitro . The objective of this study was to evaluate the effects of combination treatment in females as well as whether chronic treatment can be used without exacerbating morphine-induced tolerance and withdrawal in female and male mice. Our results demonstrate that activation of GPR171 with an agonist attenuates morphine tolerance in both female and male mice on the tail-flick test, but not the hotplate test. Importantly, the GPR171 agonist in combination with morphine does not exacerbate morphine-induced tolerance and withdrawal during long-term morphine treatment. Taken together, these data suggest that the GPR171 agonist may be combined with morphine to maintain antinociception while reducing the dose of morphine and therefore reducing side effects and abuse liability. The outcome of this study is clearly an important step toward understanding the functional interactions between opioid receptors and GPR171 and developing safer therapeutics for long-term pain management.
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Affiliation(s)
| | - Max V. McDermott
- Department of Biology
- Interdisciplinary Neuroscience Program, Utah State University, Logan, Utah
| | - Ashif I. Bhuiyan
- Chemistry and Biochemistry Department, Queens College of The City University of New York, Flushing, New York
- Chemistry Doctoral Program
| | - Sanjai K. Pathak
- Chemistry and Biochemistry Department, Queens College of The City University of New York, Flushing, New York
- Chemistry Doctoral Program
- Biochemistry Doctoral Program, The Graduate Center of The City University of New York, New York
| | - Erin N. Bobeck
- Department of Biology
- Interdisciplinary Neuroscience Program, Utah State University, Logan, Utah
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Ram A, Edwards T, McCarty A, Afrose L, McDermott MV, Bobeck EN. GPR171 Agonist Reduces Chronic Neuropathic and Inflammatory Pain in Male, But Not Female Mice. FRONTIERS IN PAIN RESEARCH (LAUSANNE, SWITZERLAND) 2022; 2:695396. [PMID: 35295419 PMCID: PMC8915562 DOI: 10.3389/fpain.2021.695396] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/17/2021] [Indexed: 12/22/2022]
Abstract
Chronic pain is a growing public health crisis that requires exigent and efficacious therapeutics. GPR171 is a promising therapeutic target that is widely expressed through the brain, including within the descending pain modulatory regions. Here, we explore the therapeutic potential of the GPR171 agonist, MS15203, in its ability to alleviate chronic pain in male and female mice using a once-daily systemic dose (10 mg/kg, i.p.) of MS15203 over the course of 5 days. We found that in our models of Complete Freund's Adjuvant (CFA)-induced inflammatory pain and chemotherapy-induced peripheral neuropathy (CIPN), MS15203 did not alleviate thermal hypersensitivity and allodynia, respectively, in female mice. On the other hand, MS15203 treatment decreased the duration of thermal hypersensitivity in CFA-treated male mice following 3 days of once-daily administration. MS15203 treatment also produced an improvement in allodynia in male mice, but not female mice, in neuropathic pain after 5 days of treatment. Gene expression of GPR171 and that of its endogenous ligand BigLEN, encoded by the gene PCSK1N, were unaltered within the periaqueductal gray (PAG) in both male and female mice following inflammatory and neuropathic pain. However, following neuropathic pain in male mice, the protein levels of GPR171 were decreased in the PAG. Treatment with MS15203 then rescued the protein levels of GPR171 in the PAG of these mice. Taken together, our results identify GPR171 as a GPCR that displays sexual dimorphism in alleviation of chronic pain. Further, our results suggest that GPR171 and MS15203 have demonstrable therapeutic potential in the treatment of chronic pain.
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Affiliation(s)
- Akila Ram
- Department of Biology, Utah State University, Logan, UT, United States
| | - Taylor Edwards
- Department of Biology, Utah State University, Logan, UT, United States
| | - Ashley McCarty
- Department of Biology, Utah State University, Logan, UT, United States
| | - Leela Afrose
- Department of Biology, Utah State University, Logan, UT, United States
| | - Max V McDermott
- Department of Biology, Utah State University, Logan, UT, United States.,Interdisciplinary Neuroscience Program, Utah State University, Logan, UT, United States
| | - Erin N Bobeck
- Department of Biology, Utah State University, Logan, UT, United States.,Interdisciplinary Neuroscience Program, Utah State University, Logan, UT, United States
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