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Nelson TS, Taylor BK. Targeting spinal neuropeptide Y1 receptor-expressing interneurons to alleviate chronic pain and itch. Prog Neurobiol 2020; 196:101894. [PMID: 32777329 DOI: 10.1016/j.pneurobio.2020.101894] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/08/2020] [Accepted: 08/03/2020] [Indexed: 02/06/2023]
Abstract
An accelerating basic science literature is providing key insights into the mechanisms by which spinal neuropeptide Y (NPY) inhibits chronic pain. A key target of pain inhibition is the Gi-coupled neuropeptide Y1 receptor (Y1). Y1 is located in key sites of pain transmission, including the peptidergic subpopulation of primary afferent neurons and a dense subpopulation of small, excitatory, glutamatergic/somatostatinergic interneurons (Y1-INs) that are densely expressed in the dorsal horn, particularly in superficial lamina I-II. Selective ablation of spinal Y1-INs with an NPY-conjugated saporin neurotoxin attenuates the development of peripheral nerve injury-induced mechanical and cold hypersensitivity. Conversely, conditional knockdown of NPY expression or intrathecal administration of Y1 antagonists reinstates hypersensitivity in models of chronic latent pain sensitization. These and other results indicate that spinal NPY release and the consequent inhibition of pain facilitatory Y1-INs represent an important mechanism of endogenous analgesia. This mechanism can be mimicked with exogenous pharmacological approaches (e.g. intrathecal administration of Y1 agonists) to inhibit mechanical and thermal hypersensitivity and spinal neuron activity in rodent models of neuropathic, inflammatory, and postoperative pain. Pharmacological activation of Y1 also inhibits mechanical- and histamine-induced itch. These immunohistochemical, pharmacological, and cell type-directed lesioning data, in combination with recent transcriptomic findings, point to Y1-INs as a promising therapeutic target for the development of spinally directed NPY-Y1 agonists to treat both chronic pain and itch.
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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, USA; Center for the Neural Basis of Cognition, University of Pittsburgh, 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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Marvizon JC, Chen W, Fu W, Taylor BK. Neuropeptide Y release in the rat spinal cord measured with Y1 receptor internalization is increased after nerve injury. Neuropharmacology 2019; 158:107732. [PMID: 31377198 DOI: 10.1016/j.neuropharm.2019.107732] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 07/31/2019] [Indexed: 12/18/2022]
Abstract
Neuropeptide Y (NPY) modulates nociception in the spinal cord, but little is known about its mechanisms of release. We measured NPY release in situ using the internalization of its Y1 receptor in dorsal horn neurons. Y1 receptor immunoreactivity was normally localized to the cell surface, but addition of NPY to spinal cord slices increased the number of neurons with Y1 internalization in a biphasic fashion (EC50s of 1 nM and 1 μM). Depolarization with KCl, capsaicin, or the protein kinase A activator 6-benzoyl-cAMP also induced Y1 receptor internalization, presumably by releasing NPY. NMDA receptor activation in the presence of BVT948, an inhibitor of protein tyrosine phosphatases, also released NPY. Electrical stimulation of the dorsal horn frequency-dependently induced NPY release; and this was decreased by the Y1 antagonist BIBO3304, the Nav channel blocker lidocaine, or the Cav2 channel blocker ω-conotoxin MVIIC. Dorsal root immersion in capsaicin, but not its electrical stimulation, also induced NPY release. This was blocked by CNQX, suggesting that part of the NPY released by capsaicin was from dorsal horn neurons receiving synapses from primary afferents and not from the afferent themselves. Mechanical stimulation in vivo, with rub or clamp of the hindpaw, elicited robust Y1 receptor internalization in rats with spared nerve injury but not sham surgery. In summary, NPY is released from dorsal horn interneurons or primary afferent terminals by electrical stimulation and by activation of TRPV1, PKA or NMDA receptors in. Furthermore, NPY release evoked by noxious and tactile stimuli increases after peripheral nerve injury.
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Affiliation(s)
- Juan Carlos Marvizon
- Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA; Veteran Affairs Greater Los Angeles Healthcare System, 11310 Wilshire Blvd., Building 115, Los Angeles, CA, 90073, USA.
| | - Wenling Chen
- Vatche and Tamar Manoukian Division of Digestive Diseases, 900 Veterans Ave., Warren Hall Building, Department of Medicine, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA, 90095, USA; Veteran Affairs Greater Los Angeles Healthcare System, 11310 Wilshire Blvd., Building 115, Los Angeles, CA, 90073, USA.
| | - Weisi Fu
- Department of Physiology, University of Kentucky Medical Center, Lexington, KY, USA.
| | - Bradley K Taylor
- Department of Physiology, University of Kentucky Medical Center, Lexington, KY, USA; Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research and the Pittsburgh Project to end Opioid Misuse, University of Pittsburgh, Pittsburgh, PA, USA.
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Abstract
Hyperalgesia and allodynia are frequent symptoms of disease and may be useful adaptations to protect vulnerable tissues. Both may, however, also emerge as diseases in their own right. Considerable progress has been made in developing clinically relevant animal models for identifying the most significant underlying mechanisms. This review deals with experimental models that are currently used to measure (sect. II) or to induce (sect. III) hyperalgesia and allodynia in animals. Induction and expression of hyperalgesia and allodynia are context sensitive. This is discussed in section IV. Neuronal and nonneuronal cell populations have been identified that are indispensable for the induction and/or the expression of hyperalgesia and allodynia as summarized in section V. This review focuses on highly topical spinal mechanisms of hyperalgesia and allodynia including intrinsic and synaptic plasticity, the modulation of inhibitory control (sect. VI), and neuroimmune interactions (sect. VII). The scientific use of language improves also in the field of pain research. Refined definitions of some technical terms including the new definitions of hyperalgesia and allodynia by the International Association for the Study of Pain are illustrated and annotated in section I.
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Affiliation(s)
- Jürgen Sandkühler
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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Tsai YJ, Lin CT, Lue JH. Characterization of the Induced Neuropeptide Y–Like Immunoreactivity in Primary Sensory Neurons following Complete Median Nerve Transection. J Neurotrauma 2007; 24:1878-88. [DOI: 10.1089/neu.2007.3488] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Yi-Ju Tsai
- School of Medicine, College of Medicine, Fu Jen Catholic University, Taipei, Taiwan
| | - Chi-Te Lin
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - June-Horng Lue
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Guedes RP, Marchi MI, Achaval M, Partata WA. Complete sciatic nerve transection induces increase of neuropeptide Y-like immunoreactivity in primary sensory neurons and spinal cord of frogs. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:461-7. [PMID: 15596391 DOI: 10.1016/j.cbpb.2004.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2004] [Revised: 10/02/2004] [Accepted: 10/03/2004] [Indexed: 01/06/2023]
Abstract
Neuropeptide Y (NPY) was immunohistochemically investigated in the frog spinal cord and dorsal root ganglia after axotomy. In normal ganglia, moderate NPY-like immunoreactivity (NPY-IR) prevailed in large and medium cells. In the spinal cord, the NPY-IR was densest in the dorsal part of the lateral funiculus. Other fibers and neurons NPY-IR were observed in the dorsal and ventral terminal fields and mediolateral band. NPY-IR fibers were also found in the ventral horn and in the ventral and lateral funiculi. The sciatic nerve transection increased the NPY-IR in large and medium neurons of the ipsilateral and contralateral dorsal root ganglia at 3 and 7 days, but no clear change was found at 15 days. In the spinal cord, there was a bilateral increase in the NPY-IR of the dorsal part of the lateral funiculus. In the ipsilateral side, the NPY-IR was increased at 3 and 7 days but was decreased at 15 days. In the contralateral side, a significant reduction at 15 days occurred. These findings seem to favor the role of NPY in the modulation of pain-related information in frogs, suggesting that this role of NPY may have appeared early in vertebrate evolution.
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Affiliation(s)
- Renata P Guedes
- Laboratório de Neurobiologia Comparada, Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite, 500, 90050-170, Porto Alegre, RS, Brazil.
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Bao L, Wang HF, Cai HJ, Tong YG, Jin SX, Lu YJ, Grant G, Hökfelt T, Zhang X. Peripheral axotomy induces only very limited sprouting of coarse myelinated afferents into inner lamina II of rat spinal cord. Eur J Neurosci 2002; 16:175-85. [PMID: 12169100 DOI: 10.1046/j.1460-9568.2002.02080.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peripheral axotomy-induced sprouting of thick myelinated afferents (A-fibers) from laminae III-IV into laminae I-II of the spinal cord is a well-established hypothesis for the structural basis of neuropathic pain. However, we show here that the cholera toxin B subunit (CTB), a neuronal tracer used to demonstrate the sprouting of A-fibers in several earlier studies, also labels unmyelinated afferents (C-fibers) in lamina II and thin myelinated afferents in lamina I, when applied after peripheral nerve transection. The lamina II afferents also contained vasoactive intestinal polypeptide and galanin, two neuropeptides mainly expressed in small dorsal root ganglion (DRG) neurons and C-fibers. In an attempt to label large DRG neurons and A-fibers selectively, CTB was applied four days before axotomy (pre-injury-labelling), and sprouting was monitored after axotomy. We found that only a small number of A-fibers sprouted into inner lamina II, a region normally innervated by C-fibers, but not into outer lamina II or lamina I. Such sprouts made synaptic contact with dendrites in inner lamina II. Neuropeptide Y (NPY) was found in these sprouts in inner lamina II, an area very rich in Y1 receptor-positive processes. These results suggest that axotomy-induced sprouting from deeper to superficial layers is much less pronounced than previously assumed, in fact it is only marginal. This limited reorganization involves large NPY immunoreactive DRG neurons sprouting into the Y1 receptor-rich inner lamina II. Even if quantitatively small, it cannot be excluded that this represents a functional circuitry involved in neuropathic pain.
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MESH Headings
- Afferent Pathways/physiology
- Afferent Pathways/ultrastructure
- Animals
- Cells, Cultured
- Cholera Toxin/metabolism
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Immunohistochemistry
- Male
- Microscopy, Electron
- Nerve Crush
- Nerve Fibers, Myelinated/physiology
- Nerve Fibers, Myelinated/ultrastructure
- Nerve Fibers, Unmyelinated/physiology
- Nerve Fibers, Unmyelinated/ultrastructure
- Nerve Regeneration/physiology
- Neurofilament Proteins/metabolism
- Neuronal Plasticity/physiology
- Neuropeptide Y/metabolism
- Posterior Horn Cells/physiology
- Posterior Horn Cells/ultrastructure
- Presynaptic Terminals/physiology
- Presynaptic Terminals/ultrastructure
- Rats
- Rats, Sprague-Dawley
- Receptors, Neuropeptide Y/metabolism
- Sciatic Nerve/injuries
- Sciatic Nerve/physiology
- Sciatic Nerve/surgery
- Spinal Nerve Roots/physiology
- Spinal Nerve Roots/ultrastructure
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Affiliation(s)
- Lan Bao
- Laboratory of Sensory System, Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, P. R. China
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