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Qi Y, Nelson TS, Prasoon P, Norris C, Taylor BK. Contribution of µ Opioid Receptor-expressing Dorsal Horn Interneurons to Neuropathic Pain-like Behavior in Mice. Anesthesiology 2023; 139:840-857. [PMID: 37566700 PMCID: PMC10840648 DOI: 10.1097/aln.0000000000004735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2023]
Abstract
BACKGROUND Intersectional genetics have yielded tremendous advances in our understanding of molecularly identified subpopulations and circuits within the dorsal horn in neuropathic pain. The authors tested the hypothesis that spinal µ opioid receptor-expressing neurons (Oprm1-expressing neurons) contribute to behavioral hypersensitivity and neuronal sensitization in the spared nerve injury model in mice. METHODS The authors coupled the use of Oprm1Cre transgenic reporter mice with whole cell patch clamp electrophysiology in lumbar spinal cord slices to evaluate the neuronal activity of Oprm1-expressing neurons in the spared nerve injury model of neuropathic pain. The authors used a chemogenetic approach to activate or inhibit Oprm1-expressing neurons, followed by the assessment of behavioral signs of neuropathic pain. RESULTS The authors reveal that spared nerve injury yielded a robust neuroplasticity of Oprm1-expressing neurons. Spared nerve injury reduced Oprm1 gene expression in the dorsal horn as well as the responsiveness of Oprm1-expressing neurons to the selective µ agonist (D-Ala2, N-MePhe4, Gly-ol)-enkephalin (DAMGO). Spared nerve injury sensitized Oprm1-expressing neurons, as reflected by an increase in their intrinsic excitability (rheobase, sham 38.62 ± 25.87 pA [n = 29]; spared nerve injury, 18.33 ± 10.29 pA [n = 29], P = 0.0026) and spontaneous synaptic activity (spontaneous excitatory postsynaptic current frequency in delayed firing neurons: sham, 0.81 ± 0.67 Hz [n = 14]; spared nerve injury, 1.74 ± 1.68 Hz [n = 10], P = 0.0466), and light brush-induced coexpression of the immediate early gene product, Fos in laminae I to II (%Fos/tdTomato+: sham, 0.42 ± 0.57% [n = 3]; spared nerve injury, 28.26 ± 1.92% [n = 3], P = 0.0001). Chemogenetic activation of Oprm1-expressing neurons produced mechanical hypersensitivity in uninjured mice (saline, 2.91 ± 1.08 g [n = 6]; clozapine N-oxide, 0.65 ± 0.34 g [n = 6], P = 0.0006), while chemogenetic inhibition reduced behavioral signs of mechanical hypersensitivity (saline, 0.38 ± 0.37 g [n = 6]; clozapine N-oxide, 1.05 ± 0.42 g [n = 6], P = 0.0052) and cold hypersensitivity (saline, 6.89 ± 0.88 s [n = 5] vs. clozapine N-oxide, 2.31 ± 0.52 s [n = 5], P = 0.0017). CONCLUSIONS The authors conclude that nerve injury sensitizes pronociceptive µ opioid receptor-expressing neurons in mouse dorsal horn. Nonopioid strategies to inhibit these interneurons might yield new treatments for neuropathic pain. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Yanmei Qi
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tyler S. Nelson
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Christopher Norris
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to end Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Nelson TS, Allen HN, Basu P, Prasoon P, Nguyen E, Arokiaraj CM, Santos DF, Seal RP, Ross SE, Todd AJ, Taylor BK. Alleviation of neuropathic pain with neuropeptide Y requires spinal Npy1r interneurons that coexpress Grp. JCI Insight 2023; 8:e169554. [PMID: 37824208 PMCID: PMC10721324 DOI: 10.1172/jci.insight.169554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 10/04/2023] [Indexed: 10/14/2023] Open
Abstract
Neuropeptide Y targets the Y1 receptor (Y1) in the spinal dorsal horn (DH) to produce endogenous and exogenous analgesia. DH interneurons that express Y1 (Y1-INs; encoded by Npy1r) are necessary and sufficient for neuropathic hypersensitivity after peripheral nerve injury. However, as Y1-INs are heterogenous in composition in terms of morphology, neurophysiological characteristics, and gene expression, we hypothesized that a more precisely defined subpopulation mediates neuropathic hypersensitivity. Using fluorescence in situ hybridization, we found that Y1-INs segregate into 3 largely nonoverlapping subpopulations defined by the coexpression of Npy1r with gastrin-releasing peptide (Grp/Npy1r), neuropeptide FF (Npff/Npy1r), and cholecystokinin (Cck/Npy1r) in the superficial DH of mice, nonhuman primates, and humans. Next, we analyzed the functional significance of Grp/Npy1r, Npff/Npy1r, and Cck/Npy1r INs to neuropathic pain using a mouse model of peripheral nerve injury. We found that chemogenetic inhibition of Npff/Npy1r-INs did not change the behavioral signs of neuropathic pain. Further, inhibition of Y1-INs with an intrathecal Y1 agonist, [Leu31, Pro34]-NPY, reduced neuropathic hypersensitivity in mice with conditional deletion of Npy1r from CCK-INs and NPFF-INs but not from GRP-INs. We conclude that Grp/Npy1r-INs are conserved in higher order mammalian species and represent a promising and precise pharmacotherapeutic target for the treatment of neuropathic pain.
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Affiliation(s)
- Tyler S. Nelson
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Center for Neuroscience
| | - Heather N. Allen
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Pittsburgh Center for Pain Research, and
| | - Paramita Basu
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Pittsburgh Center for Pain Research, and
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Pittsburgh Center for Pain Research, and
| | - Eileen Nguyen
- Center for Neuroscience
- Pittsburgh Center for Pain Research, and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Cynthia M. Arokiaraj
- Center for Neuroscience
- Pittsburgh Center for Pain Research, and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Diogo F.S. Santos
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Pittsburgh Center for Pain Research, and
| | - Rebecca P. Seal
- Center for Neuroscience
- Pittsburgh Center for Pain Research, and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sarah E. Ross
- Center for Neuroscience
- Pittsburgh Center for Pain Research, and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Andrew J. Todd
- Spinal Cord Group, School of Psychology and Neuroscience, University of Glasgow, Glasgow, United Kingdom
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine
- Pittsburgh Project to end Opioid Misuse
- Center for Neuroscience
- Pittsburgh Center for Pain Research, and
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Nelson TS, Sinha GP, Santos DFS, Jukkola P, Prasoon P, Winter MK, McCarson KE, Smith BN, Taylor BK. Spinal neuropeptide Y Y1 receptor-expressing neurons are a pharmacotherapeutic target for the alleviation of neuropathic pain. Proc Natl Acad Sci U S A 2022; 119:e2204515119. [PMID: 36343228 PMCID: PMC9674229 DOI: 10.1073/pnas.2204515119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 09/25/2022] [Indexed: 11/09/2022] Open
Abstract
Peripheral nerve injury sensitizes a complex network of spinal cord dorsal horn (DH) neurons to produce allodynia and neuropathic pain. The identification of a druggable target within this network has remained elusive, but a promising candidate is the neuropeptide Y (NPY) Y1 receptor-expressing interneuron (Y1-IN) population. We report that spared nerve injury (SNI) enhanced the excitability of Y1-INs and elicited allodynia (mechanical and cold hypersensitivity) and affective pain. Similarly, chemogenetic or optogenetic activation of Y1-INs in uninjured mice elicited behavioral signs of spontaneous, allodynic, and affective pain. SNI-induced allodynia was reduced by chemogenetic inhibition of Y1-INs, or intrathecal administration of a Y1-selective agonist. Conditional deletion of Npy1r in DH neurons, but not peripheral afferent neurons prevented the anti-hyperalgesic effects of the intrathecal Y1 agonist. We conclude that spinal Y1-INs are necessary and sufficient for the behavioral symptoms of neuropathic pain and represent a promising target for future pharmacotherapeutic development of Y1 agonists.
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Affiliation(s)
- Tyler S. Nelson
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA 15261
| | - Ghanshyam P. Sinha
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Diogo F. S. Santos
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Peter Jukkola
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Michelle K. Winter
- Kansas Intellectual and Developmental Disabilities Research Center; Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160
| | - Ken E. McCarson
- Kansas Intellectual and Developmental Disabilities Research Center; Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160
| | - Bret N. Smith
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536
| | - Bradley K. Taylor
- Department of Anesthesiology and Perioperative Medicine, Center for Neuroscience, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
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Zhu M, Yan Y, Cao X, Zeng F, Xu G, Shen W, Li F, Luo L, Wang Z, Zhang Y, Zhang X, Zhang D, Liu T. Electrophysiological and Morphological Features of Rebound Depolarization Characterized Interneurons in Rat Superficial Spinal Dorsal Horn. Front Cell Neurosci 2021; 15:736879. [PMID: 34621158 PMCID: PMC8490703 DOI: 10.3389/fncel.2021.736879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 08/25/2021] [Indexed: 11/18/2022] Open
Abstract
Substantia gelatinosa (SG) neurons, which are located in the spinal dorsal horn (lamina II), have been identified as the “central gate” for the transmission and modulation of nociceptive information. Rebound depolarization (RD), a biophysical property mediated by membrane hyperpolarization that is frequently recorded in the central nervous system, contributes to shaping neuronal intrinsic excitability and, in turn, contributes to neuronal output and network function. However, the electrophysiological and morphological properties of SG neurons exhibiting RD remain unclarified. In this study, whole-cell patch-clamp recordings were performed on SG neurons from parasagittal spinal cord slices. RD was detected in 44.44% (84 out of 189) of the SG neurons recorded. We found that RD-expressing neurons had more depolarized resting membrane potentials, more hyperpolarized action potential (AP) thresholds, higher AP amplitudes, shorter AP durations, and higher spike frequencies in response to depolarizing current injection than neurons without RD. Based on their firing patterns and morphological characteristics, we propose that most of the SG neurons with RD mainly displayed tonic firing (69.05%) and corresponded to islet cell morphology (58.82%). Meanwhile, subthreshold currents, including the hyperpolarization-activated cation current (Ih) and T-type calcium current (IT), were identified in SG neurons with RD. Blockage of Ih delayed the onset of the first spike in RD, while abolishment of IT significantly blunted the amplitude of RD. Regarding synaptic inputs, SG neurons with RD showed lower frequencies in both spontaneous and miniature excitatory synaptic currents. Furthermore, RD-expressing neurons received either Aδ- or C-afferent-mediated monosynaptic and polysynaptic inputs. However, RD-lacking neurons received afferents from monosynaptic and polysynaptic Aδ fibers and predominantly polysynaptic C-fibers. These findings demonstrate that SG neurons with RD have a specific cell-type distribution, and may differentially process somatosensory information compared to those without RD.
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Affiliation(s)
- Mengye Zhu
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Yi Yan
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Xuezhong Cao
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Fei Zeng
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Gang Xu
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Wei Shen
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Fan Li
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Lingyun Luo
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Zhijian Wang
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Yong Zhang
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Xuexue Zhang
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Daying Zhang
- Department of Pain Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China.,Institute of Pain Medicine, Jiangxi Academy of Clinical and Medical Sciences, Nanchang, China
| | - Tao Liu
- Center for Experimental Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, China
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