1
|
Niella RV, Corrêa JMX, dos Santos JFR, Lima LF, Marques CSDC, Santos LC, Santana LR, Silva ÁJC, Farias KS, Pirovani CP, Silva JF, de Lavor MSL. Post-treatment with maropitant reduces oxidative stress, endoplasmic reticulum stress and neuroinflammation on peripheral nerve injury in rats. PLoS One 2024; 19:e0287390. [PMID: 38507417 PMCID: PMC10954158 DOI: 10.1371/journal.pone.0287390] [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] [Received: 01/04/2023] [Accepted: 06/05/2023] [Indexed: 03/22/2024] Open
Abstract
OBJECTIVE To determine the effective dose and therapeutic potential of maropitant using through expression of mediators of oxidative stress, inflammatory and of the unfolded protein response (UPR) (bio) markers on spinal cord using a model of neuropathic pain induced through chronic constriction injury (CCI) in rats. STUDY DESIGN Randomized, blinded, prospective experimental study. ANIMALS 98 male Wistar rats. METHODS Rats were anesthetized with sevoflurane and after CCI, they were randomly assigned to the following groups that received: vehicle, 3, 6, 15, 30 e 50 mg/kg/24q of maropitant. The effect on inflammatory mediators (IL10, TNFα), oxidative stress (GPx, CAT, SOD), microglial (IBA-1) and neuronal (NeuN, TACR1) markers was evaluated though immunohistochemistry and expression levels of markers of hypoxia (HIF1α, Nrf2), antioxidant enzymes (Catalse, Sod1 and GPx1), and endoplasmic reticulum stress mediators (GRP78, CHOP and PERK) through qRT-PCR. RESULTS Intraperitoneal injection (IP) of maropitant inhibited nociception with ID50 values of 4,1 mg/kg (5,85-19,36) in a neuropathic pain model through CCI. A dose of 30 mg/kg/24q was significantly effective in reducing mechanical allodynia 1 to 4h after treatment with nociception inhibition (145,83%). A reduction in the expression of hypoxia factors (HIF1α, Nrf2) was observed, along with an increase in antioxidant activity (CAT, SOD and GPX). Additionally, there was a reduction in inflammatory markes (IL10, TNFα), microglial (IBA-1), and neuronal markers (NeuN, TACR1). CONCLUSION AND CLINICAL RELEVANCE These findings demonstrate that the determined dose, administered daily for seven days, had an antinociceptive effect, as well as anti-inflammatory and antioxidant activity.
Collapse
Affiliation(s)
- Raquel Vieira Niella
- Department of Agricultural and Environmental Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | | | | | - Larissa Ferreira Lima
- Department of Agricultural and Environmental Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | | | | | - Larissa Rodrigues Santana
- Department of Agricultural and Environmental Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | - Álvaro José Chávez Silva
- Department of Agricultural and Environmental Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | - Keilane Silva Farias
- Department of Biological Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | | | - Juneo Freitas Silva
- Department of Biological Sciences, State University of Santa Cruz, Ilhéus, Brazil
| | | |
Collapse
|
2
|
Cooper AH, Hedden NS, Prasoon P, Qi Y, Taylor BK. Postsurgical Latent Pain Sensitization Is Driven by Descending Serotonergic Facilitation and Masked by µ-Opioid Receptor Constitutive Activity in the Rostral Ventromedial Medulla. J Neurosci 2022; 42:5870-5881. [PMID: 35701159 PMCID: PMC9337598 DOI: 10.1523/jneurosci.2038-21.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 05/22/2022] [Accepted: 05/27/2022] [Indexed: 01/29/2023] Open
Abstract
Following tissue injury, latent sensitization (LS) of nociceptive signaling can persist indefinitely, kept in remission by compensatory µ-opioid receptor constitutive activity (MORCA) in the dorsal horn of the spinal cord. To demonstrate LS, we conducted plantar incision in mice and then waited 3-4 weeks for hypersensitivity to resolve. At this time (remission), systemic administration of the opioid receptor antagonist/inverse agonist naltrexone reinstated mechanical and heat hypersensitivity. We first tested the hypothesis that LS extends to serotonergic neurons in the rostral ventral medulla (RVM) that convey pronociceptive input to the spinal cord. We report that in male and female mice, hypersensitivity was accompanied by increased Fos expression in serotonergic neurons of the RVM, abolished on chemogenetic inhibition of RVM 5-HT neurons, and blocked by intrathecal injection of the 5-HT3R antagonist ondansetron; the 5-HT2AR antagonist MDL-11 939 had no effect. Second, to test for MORCA, we microinjected the MOR inverse agonist d-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP) and/or neutral opioid receptor antagonist 6β-naltrexol. Intra-RVM CTAP produced mechanical hypersensitivity at both hindpaws; 6β-naltrexol had no effect by itself, but blocked CTAP-induced hypersensitivity. This indicates that MORCA, rather than an opioid ligand-dependent mechanism, maintains LS in remission. We conclude that incision establishes LS in descending RVM 5-HT neurons that drives pronociceptive 5-HT3R signaling in the dorsal horn, and this LS is tonically opposed by MORCA in the RVM. The 5-HT3 receptor is a promising therapeutic target for the development of drugs to prevent the transition from acute to chronic postsurgical pain.SIGNIFICANCE STATEMENT Surgery leads to latent pain sensitization and a compensatory state of endogenous pain control that is maintained long after tissue healing. Here, we show that either chemogenetic inhibition of serotonergic neuron activity in the RVM or pharmacological inhibition of 5-HT3 receptor signaling at the spinal cord blocks behavioral signs of postsurgical latent sensitization. We conclude that MORCA in the RVM opposes descending serotonergic facilitation of LS and that the 5-HT3 receptor is a promising therapeutic target for the development of drugs to prevent the transition from acute to chronic postsurgical pain.
Collapse
Affiliation(s)
- Andrew H Cooper
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Naomi S Hedden
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Pranav Prasoon
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Yanmei Qi
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Bradley K Taylor
- Department of Anesthesiology and Perioperative Medicine, Pittsburgh Center for Pain Research, Pittsburgh Project to End Opioid Misuse, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| |
Collapse
|
3
|
Liedtke W. Long March Toward Safe and Effective Analgesia by Enhancing Gene Expression of Kcc2: First Steps Taken. Front Mol Neurosci 2022; 15:865600. [PMID: 35645734 PMCID: PMC9137411 DOI: 10.3389/fnmol.2022.865600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 03/08/2022] [Indexed: 11/15/2022] Open
Abstract
Low intraneuronal chloride in spinal cord dorsal horn pain relay neurons is critical for physiologic transmission of primary pain afferents because low intraneuronal chloride dictates whether GABA-ergic and glycin-ergic neurotransmission is inhibitory. If the neuronal chloride elevates to pathologic levels, then spinal cord primary pain relay becomes leaky and exhibits the behavioral hallmarks of pathologic pain, namely hypersensitivity and allodynia. Low chloride in spinal cord dorsal horn neurons is maintained by proper gene expression of Kcc2 and sustained physiologic function of the KCC2 chloride extruding electroneutral transporter. Peripheral nerve injury and other forms of neural injury evoke greatly diminished Kcc2 gene expression and subsequent corruption of inhibitory neurotransmission in the spinal cord dorsal horn, thus causing derailment of the gate function for pain. Here I review key discoveries that have helped us understand these fundamentals, and focus on recent insights relating to the discovery of Kcc2 gene expression enhancing compounds via compound screens in neurons. One such study characterized the kinase inhibitor, kenpaullone, more in-depth, revealing its function as a robust and long-lasting analgesic in preclinical models of nerve injury and cancer bone pain, also elucidating its mechanism of action via GSK3β inhibition, diminishing delta-catenin phosphorylation, and facilitating its nuclear transfer and subsequent enhancement of Kcc2 gene expression by de-repressing Kaiso epigenetic transcriptional regulator. Future directions re Kcc2 gene expression enhancement are discussed, namely combination with other analgesics and analgesic methods, such as spinal cord stimulation and electroacupuncture, gene therapy, and leveraging Kcc2 gene expression-enhancing nanomaterials.
Collapse
|
4
|
WeiWei Y, WenDi F, Mengru C, Tuo Y, Chen G. The cellular mechanism by which the rostral ventromedial medulla acts on the spinal cord during chronic pain. Rev Neurosci 2021; 32:545-558. [PMID: 33565739 DOI: 10.1515/revneuro-2020-0121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 12/18/2020] [Indexed: 11/15/2022]
Abstract
Clinical therapies for chronic pain are limited. While targeted drugs are promising therapies for chronic pain, they exhibit insufficient efficacy and poor targeting. The occurrence of chronic pain partly results from central changes caused by alterations in neurons in the rostral ventromedial medulla (RVM) in the brainstem regulatory pathway. The RVM, which plays a key role in the descending pain control pathway, greatly contributes to the development and maintenance of pain. However, the exact roles of the RVM in chronic pain remain unclear, making it difficult to develop new drugs targeting the RVM and related pathways. Here, we first discuss the roles of the RVM and related circuits in chronic pain. Then, we analyze synaptic transmission between RVM neurons and spinal cord neurons, specifically focusing on the release of neurotransmitters, to explore the cellular mechanisms by which the RVM regulates chronic pain. Finally, we propose some ideas for the development of drugs targeting the RVM.
Collapse
Affiliation(s)
- Yu WeiWei
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong226001, China
| | - Fei WenDi
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong226001, China
| | - Cui Mengru
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong226001, China
| | - Yang Tuo
- Department of Hand Surgery, China-Japan Union Hospital of Jilin University, Changchun130033, China
| | - Gang Chen
- Department of Anesthesiology, Affiliated Hospital of Nantong University, Nantong226001, China.,Department of Tissue and Embryology, Medical School of Nantong University, Co-innovation Center of Neuroregeneration, Nantong University, Nantong226001, China
| |
Collapse
|
5
|
Continuous Infusion of Ketamine and Lidocaine Either with or without Maropitant as an Adjuvant Agent for Analgesia in Female Dogs Undergoing Mastectomy. Vet Med Int 2021; 2021:4747301. [PMID: 33575023 PMCID: PMC7857926 DOI: 10.1155/2021/4747301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 11/26/2020] [Accepted: 01/02/2021] [Indexed: 11/17/2022] Open
Abstract
Maropitant, an antagonist of neurokinin-1 (NK-1) receptors, blocks the pharmacological action of substance P on the central and peripheral nervous systems. The objective of this study was to compare the antinociceptive and cardiorespiratory effects of the continuous intraoperative infusion of maropitant with ketamine and lidocaine in female dogs undergoing unilateral radical mastectomy. Twenty-four female dogs were used and were divided randomly into two groups (n = 12). The GLK group received ketamine bolus (1.0 mg/kg), lidocaine bolus (1.5 mg/kg), and continuous infusion of ketamine and lidocaine (10 mcg/kg/min and 50 mcg/kg/min), respectively; the GLKM group received the same anesthetic protocol combined with maropitant bolus (1.5 mg/kg/IV) and continuous infusion of maropitant (100 mcg/kg/h). Continuous infusion was initiated at the start of surgery and was maintained until 1 hour postoperatively. Pain was evaluated in the postoperative period using four scales and a digital analgesimeter. Data were analysed using analysis of variance, Student's t-test, Mann–Whitney test, and Friedman's test (P < 0.05). Kaplan–Meier curves were compared using the log-rank test. The results indicated lower pain scores, better survival curves with a lower number of patients requiring rescue analgesia, and lower peripheral sensitization, in the GLKM group than in the GLK group. It was concluded that the coadministration of maropitant with ketamine and lidocaine had an adjuvant effect with minimal cardiorespiratory effects and effective analgesia, improving pain management and patient comfort.
Collapse
|
6
|
Li ZL, Xue Y, Tao ZY, Du WZ, Jiang YG, Cao DY. Spinal 5-HT 3 receptor contributes to somatic hyperalgesia induced by sub-chronic stress. Mol Pain 2020; 15:1744806919859723. [PMID: 31184246 PMCID: PMC6613060 DOI: 10.1177/1744806919859723] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Zhuo-Lin Li
- 1 Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China.,2 Department of Endodontics, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Yang Xue
- 1 Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Zhuo-Ying Tao
- 1 Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Wen-Zhi Du
- 1 Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Yue-Gui Jiang
- 2 Department of Endodontics, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Dong-Yuan Cao
- 1 Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| |
Collapse
|
7
|
Nakamura Y, Fukushige R, Watanabe K, Kishida Y, Hisaoka-Nakashima K, Nakata Y, Morioka N. Continuous infusion of substance P into rat striatum relieves mechanical hypersensitivity caused by a partial sciatic nerve ligation via activation of striatal muscarinic receptors. Behav Brain Res 2020; 391:112714. [PMID: 32461131 DOI: 10.1016/j.bbr.2020.112714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 05/12/2020] [Accepted: 05/16/2020] [Indexed: 12/14/2022]
Abstract
Previous studies have demonstrated that continuous substance P (SP) infusion into the rat striatum attenuated hind paw formalin-induced nociceptive behaviors and mechanical hypersensitivity via a neurokinin-1 (NK1) receptor dependent mechanism. However, whether there is a role of striatal infusion of SP on chronic, neuropathic pain has yet to be demonstrated. The present study investigated the effect of continuous SP infusion into the rat striatum using a reverse microdialysis method is antinociceptive in a rat model of chronic, mononeuropathic pain. Two weeks after partial sciatic nerve injury, the ipsilateral hind paw demonstrated mechanical hypersensitivity. Infusion of SP (0.2, 0.4, or 0.8 μg/mL, 1 μL/min) for 120 min into the contralateral striatum dose-dependently relieved mechanical hypersensitivity. The antinociceptive effect of SP infusion was inhibited by co-infusion with the NK1 receptor antagonist CP96345 (10 μM). Neither ipsilateral continuous infusion nor acute microinjection of SP (10 ng) into the contralateral striatum was antinociceptive. A role of striatal muscarinic cholinergic neurons is suggested since co-infusion of SP with atropine (10 μM), but not the nicotinic receptor mecamylamine (10 μM), blocked antinociception. The current study suggests that activation of striatal muscarinic receptors through NK1 receptors could be a novel approach to managing chronic pain.
Collapse
Affiliation(s)
- Yoki Nakamura
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Ryo Fukushige
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Kohei Watanabe
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Yuki Kishida
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan
| | - Norimitsu Morioka
- Department of Pharmacology, Graduate School of Biomedical & Health Sciences, Hiroshima University, Japan.
| |
Collapse
|
8
|
Ion Channels Involved in Substance P-Mediated Nociception and Antinociception. Int J Mol Sci 2019; 20:ijms20071596. [PMID: 30935032 PMCID: PMC6479580 DOI: 10.3390/ijms20071596] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 03/26/2019] [Accepted: 03/27/2019] [Indexed: 02/07/2023] Open
Abstract
Substance P (SP), an 11-amino-acid neuropeptide, has long been considered an effector of pain. However, accumulating studies have proposed a paradoxical role of SP in anti-nociception. Here, we review studies of SP-mediated nociception and anti-nociception in terms of peptide features, SP-modulated ion channels, and differential effector systems underlying neurokinin 1 receptors (NK1Rs) in differential cell types to elucidate the effect of SP and further our understanding of SP in anti-nociception. Most importantly, understanding the anti-nociceptive SP-NK1R pathway would provide new insights for analgesic drug development.
Collapse
|
9
|
Increase of histone acetylation in the GABAergic neurons in the rostral ventromedial medulla associated with mechanical hypersensitivity after repeated restraint stress. Brain Res Bull 2018; 142:394-402. [DOI: 10.1016/j.brainresbull.2018.09.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 01/31/2023]
|
10
|
NMDA Receptor Dependent Long-term Potentiation in Chronic Pain. Neurochem Res 2018; 44:531-538. [PMID: 30109556 PMCID: PMC6420414 DOI: 10.1007/s11064-018-2614-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/08/2018] [Accepted: 08/11/2018] [Indexed: 02/06/2023]
Abstract
Since the discovery of NMDA receptor (NMDAR) dependent long-term potentiation (LTP) in the hippocampus, many studies have demonstrated that NMDAR dependent LTP exists throughout central synapses, including those involved in sensory transmission and perception. NMDAR LTP has been reported in spinal cord dorsal horn synapses, anterior cingulate cortex and insular cortex. Behavioral, genetic and pharmacological studies show that inhibiting or reducing NMDAR LTP produced analgesic effects in animal models of chronic pain. Investigation of signalling mechanisms for NMDAR LTP may provide novel targets for future treatment of chronic pain.
Collapse
|
11
|
Khasabov SG, Malecha P, Noack J, Tabakov J, Giesler GJ, Simone DA. Hyperalgesia and sensitization of dorsal horn neurons following activation of NK-1 receptors in the rostral ventromedial medulla. J Neurophysiol 2017; 118:2727-2744. [PMID: 28794197 PMCID: PMC5675905 DOI: 10.1152/jn.00478.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 08/04/2017] [Accepted: 08/06/2017] [Indexed: 11/22/2022] Open
Abstract
Neurons in the rostral ventromedial medulla (RVM) project to the spinal cord and are involved in descending modulation of pain. Several studies have shown that activation of neurokinin-1 (NK-1) receptors in the RVM produces hyperalgesia, although the underlying mechanisms are not clear. In parallel studies, we compared behavioral measures of hyperalgesia to electrophysiological responses of nociceptive dorsal horn neurons produced by activation of NK-1 receptors in the RVM. Injection of the selective NK-1 receptor agonist Sar9,Met(O2)11-substance P (SSP) into the RVM produced dose-dependent mechanical and heat hyperalgesia that was blocked by coadministration of the selective NK-1 receptor antagonist L-733,060. In electrophysiological studies, responses evoked by mechanical and heat stimuli were obtained from identified high-threshold (HT) and wide dynamic range (WDR) neurons. Injection of SSP into the RVM enhanced responses of WDR neurons, including identified neurons that project to the parabrachial area, to mechanical and heat stimuli. Since intraplantar injection of capsaicin produces robust hyperalgesia and sensitization of nociceptive spinal neurons, we examined whether this sensitization was dependent on NK-1 receptors in the RVM. Pretreatment with L-733,060 into the RVM blocked the sensitization of dorsal horn neurons produced by capsaicin. c-Fos labeling was used to determine the spatial distribution of dorsal horn neurons that were sensitized by NK-1 receptor activation in the RVM. Consistent with our electrophysiological results, administration of SSP into the RVM increased pinch-evoked c-Fos expression in the dorsal horn. It is suggested that targeting this descending pathway may be effective in reducing persistent pain.NEW & NOTEWORTHY It is known that activation of neurokinin-1 (NK-1) receptors in the rostral ventromedial medulla (RVM), a main output area for descending modulation of pain, produces hyperalgesia. Here we show that activation of NK-1 receptors produces hyperalgesia by sensitizing nociceptive dorsal horn neurons. Targeting this pathway at its origin or in the spinal cord may be an effective approach for pain management.
Collapse
Affiliation(s)
- Sergey G Khasabov
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, Minnesota; and
| | - Patrick Malecha
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, Minnesota; and
| | - Joseph Noack
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, Minnesota; and
| | - Janneta Tabakov
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, Minnesota; and
| | - Glenn J Giesler
- Department of Neuroscience, University of Minnesota, School of Medicine, Minneapolis, Minnesota
| | - Donald A Simone
- Department of Diagnostic and Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, Minnesota; and
| |
Collapse
|
12
|
Optogenetic Evidence for a Direct Circuit Linking Nociceptive Transmission through the Parabrachial Complex with Pain-Modulating Neurons of the Rostral Ventromedial Medulla (RVM). eNeuro 2017; 4:eN-NWR-0202-17. [PMID: 28660248 PMCID: PMC5483601 DOI: 10.1523/eneuro.0202-17.2017] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 06/09/2017] [Indexed: 11/28/2022] Open
Abstract
The parabrachial complex (PB) is a functionally and anatomically complex structure involved in a range of homeostatic and sensory functions, including nociceptive transmission. There is also evidence that PB can engage descending pain-modulating systems, the best characterized of which is the rostral ventromedial medulla (RVM). Two distinct classes of RVM neurons, “ON-cells” and “OFF-cells,” exert net pronociceptive and anti-nociceptive effects, respectively. PB was recently shown to be a relay of nociceptive information to RVM ON- and OFF-cells. The present experiments used optogenetic methods in a lightly anesthetized rat and an adult RVM slice to determine whether there are direct, functionally relevant inputs to RVM pain-modulating neurons from PB. Whole-cell patch-clamp recordings demonstrated that PB conveys direct glutamatergic and GABAergic inputs to RVM neurons. Consistent with this, in vivo recording showed that nociceptive-evoked responses of ON- and OFF-cells were suppressed by optogenetic inactivation of archaerhodopsin (ArchT)-expressing PB terminals in RVM, demonstrating that a net inhibitory input to OFF-cells and net excitatory input to ON-cells are engaged by acute noxious stimulation. Further, the majority of ON- and OFF-cells responded to optogenetic activation of channelrhodopsin (ChR2)-expressing terminals in the RVM, confirming a direct PB influence on RVM pain-modulating neurons. These data show that a direct connection from the PB to the RVM conveys nociceptive information to the pain-modulating neurons of RVM under basal conditions. They also reveal additional inputs from PB with the capacity to activate both classes of RVM pain-modulating neurons and the potential to be recruited under different physiological and pathophysiological conditions.
Collapse
|
13
|
A role for neurokinin-1 receptor neurons in the rostral ventromedial medulla in the development of chronic postthoracotomy pain. Pain 2017. [DOI: 10.1097/j.pain.0000000000000919] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
14
|
Boadas-Vaello P, Homs J, Reina F, Carrera A, Verdú E. Neuroplasticity of Supraspinal Structures Associated with Pathological Pain. Anat Rec (Hoboken) 2017; 300:1481-1501. [PMID: 28263454 DOI: 10.1002/ar.23587] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/27/2016] [Accepted: 10/18/2016] [Indexed: 12/19/2022]
Abstract
Peripheral nerve and spinal cord injuries, along with other painful syndromes such as fibromyalgia, diabetic neuropathy, chemotherapeutic neuropathy, trigeminal neuralgia, complex regional pain syndrome, and/or irritable bowel syndrome, cause several neuroplasticity changes in the nervous system along its entire axis affecting the different neuronal nuclei. This paper reviews these changes, focusing on the supraspinal structures that are involved in the modulation and processing of pain, including the periaqueductal gray matter, red nucleus, locus coeruleus, rostral ventromedial medulla, thalamus, hypothalamus, basal ganglia, cerebellum, habenula, primary, and secondary somatosensory cortex, motor cortex, mammillary bodies, hippocampus, septum, amygdala, cingulated, and prefrontal cortex. Hyperexcitability caused by the modification of postsynaptic receptor expression, central sensitization, and potentiation of presynaptic delivery of neurotransmitters, as well as the reduction of inhibitory inputs, changes in dendritic spine, neural circuit remodeling, alteration of gray matter, and upregulation of proinflammatory mediators (e.g., cytokines) by reactivation of astrocytes and microglial cells are the main functional, structural, and molecular neuroplasticity changes observed in the above supraspinal structures, associated with pathological pain. Studying these changes in greater depth may lead to the implementation and improvement of new therapeutic strategies against pathological pain. Anat Rec, 300:1481-1501, 2017. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Pere Boadas-Vaello
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Judit Homs
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain.,Department of Physical Therapy EUSES-Universitat of Girona, Salt (Girona), Catalonia, 17190, Spain
| | - Francisco Reina
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Ana Carrera
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Enrique Verdú
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| |
Collapse
|
15
|
Mustafa G, Hou J, Tsuda S, Nelson R, Sinharoy A, Wilkie Z, Pandey R, Caudle RM, Neubert JK, Thompson FJ, Bose P. Trigeminal neuroplasticity underlies allodynia in a preclinical model of mild closed head traumatic brain injury (cTBI). Neuropharmacology 2016; 107:27-39. [PMID: 26972829 DOI: 10.1016/j.neuropharm.2016.03.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 03/07/2016] [Accepted: 03/08/2016] [Indexed: 01/10/2023]
Abstract
Post-traumatic headache (PTH) following TBI is a common and often persisting pain disability. PTH is often associated with a multimodal central pain sensitization on the skin surface described as allodynia. However, the particular neurobiology underlying cTBI-induced pain disorders are not known. These studies were performed to assess trigeminal sensory sensitization and to determine if sensitization measured behaviorally correlated with detectable changes in portions of the trigeminal sensory system (TSS), particularly trigeminal nucleus, thalamus, and sensory cortex. Thermal stimulation is particularly well suited to evaluate sensitization and was used in these studies. Recent advances in the use of reward/conflict paradigms permit use of operant measures of behavior, versus reflex-driven response behaviors, for thermal sensitization studies. Thus, to quantitate facial thermal sensitization (allodynia) in the setting of acute TBI, the current study utilized an operant orofacial pain reward/conflict testing paradigm to assess facial thermal sensitivity in uninjured control animals compared with those two weeks after cTBI in a rodent model. Significant reductions in facial contact/lick behaviors were observed in the TBI animals using either cool or warm challenge temperatures compared with behaviors in the normal animals. These facial thermal sensitizations correlated with detectable changes in multiple levels of the TSS. The immunohistochemical (IHC) studies revealed significant alterations in the expression of the serotonin (5-HT), neurokinin 1 receptor (NK1R), norepinephrine (NE), and gamma-aminobutyric acid (GABA) in the caudal trigeminal nucleus, thalamic VPL/VPM nucleus, and sensory cortex of the orofacial pain pathways. There was a strong correlation between increased expression of certain IHC markers and increased behavioral markers for facial sensitization. The authors conclude that TBI-induced changes observed in the TSS are consistent with the expression of generalized facial allodynia following cTBI. To our knowledge, this is the first report of orofacial sensitization correlated with changes in selected neuromodulators/neurotransmitters in the TSS following experimental mild TBI.
Collapse
Affiliation(s)
- Golam Mustafa
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA; Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0144, USA
| | - Jiamei Hou
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA; Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0144, USA
| | - Shigeharu Tsuda
- Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0144, USA
| | - Rachel Nelson
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA
| | - Ankita Sinharoy
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA
| | - Zachary Wilkie
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA
| | - Rahul Pandey
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA
| | - Robert M Caudle
- Department of Oral and Maxillofacial Surgery, College of Dentistry, University of Florida, Gainesville, FL 32610-0244, USA
| | - John K Neubert
- Department of Orthodontics, College of Dentistry, University of Florida, Gainesville, FL 32610-0244, USA
| | - Floyd J Thompson
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA; Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0144, USA; Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610-0244, USA
| | - Prodip Bose
- Brain Rehabilitation Research Center of Excellence, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608-1197, USA; Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0144, USA; Department of Neurology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610-0236, USA.
| |
Collapse
|
16
|
Boadas-Vaello P, Castany S, Homs J, Álvarez-Pérez B, Deulofeu M, Verdú E. Neuroplasticity of ascending and descending pathways after somatosensory system injury: reviewing knowledge to identify neuropathic pain therapeutic targets. Spinal Cord 2016; 54:330-40. [DOI: 10.1038/sc.2015.225] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 11/25/2015] [Accepted: 11/28/2015] [Indexed: 12/16/2022]
|
17
|
Maduka UP, Hamity MV, Walder RY, White SR, Li Y, Hammond DL. Changes in the disposition of substance P in the rostral ventromedial medulla after inflammatory injury in the rat. Neuroscience 2016; 317:1-11. [PMID: 26762802 DOI: 10.1016/j.neuroscience.2015.12.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 12/22/2015] [Accepted: 12/30/2015] [Indexed: 12/21/2022]
Abstract
This study examined whether peripheral inflammatory injury increases the levels or changes the disposition of substance P (SubP) in the rostral ventromedial medulla (RVM), which serves as a central relay in bulbospinal pathways of pain modulation. Enzyme immunoassay and reverse transcriptase quantitative polymerase chain reaction were used to measure SubP protein and transcript, respectively, in tissue homogenates prepared from the RVM and the periaqueductal gray (PAG) and cuneiform nuclei of rats that had received an intraplantar injection of saline or complete Freund's adjuvant (CFA). Matrix-Assisted Laser Desorption/Ionization Time of Flight analysis confirmed that the RVM does not contain hemokinin-1 (HK-1), which can confound measurements of SubP because it is recognized equally well by commercial antibodies for SubP. Levels of SubP protein in the RVM were unchanged four hours, four days and two weeks after injection of CFA. Tac1 transcripts were similarly unchanged in the RVM four days or two weeks after CFA. In contrast, the density of SubP immunoreactive processes in the RVM increased 2-fold within four hours and 2.7-fold four days after CFA injection; it was unchanged at two weeks. SubP-immunoreactive processes in the RVM include axon terminals of neurons located in the PAG and cuneiform nucleus. SubP content in homogenates of the PAG and cuneiform nucleus was significantly increased four days after CFA, but not at four hours or two weeks. Tac1 transcripts in homogenates of these nuclei were unchanged four days and two weeks after CFA. These findings suggest that there is an increased mobilization of SubP within processes in the RVM shortly after injury accompanied by an increased synthesis of SubP in neurons that project to the RVM. These findings are consonant with the hypothesis that an increase in SubP release in the RVM contributes to the hyperalgesia that develops after peripheral inflammatory injury.
Collapse
Affiliation(s)
- U P Maduka
- Departments of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - M V Hamity
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - R Y Walder
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - S R White
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - Y Li
- Proteomics Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States
| | - D L Hammond
- Departments of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
| |
Collapse
|
18
|
Hamity MV, Walder RY, Hammond DL. Increased neuronal expression of neurokinin-1 receptor and stimulus-evoked internalization of the receptor in the rostral ventromedial medulla of the rat after peripheral inflammatory injury. J Comp Neurol 2015; 522:3037-51. [PMID: 24639151 DOI: 10.1002/cne.23564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/31/2014] [Accepted: 02/18/2014] [Indexed: 12/28/2022]
Abstract
This study examined possible mechanisms by which Substance P (Sub P) assumes a pronociceptive role in the rostral ventromedial medulla (RVM) under conditions of peripheral inflammatory injury, in this case produced by intraplantar (ipl) injection of complete Freund's adjuvant (CFA). In saline- and CFA-treated rats, neurokinin-1 receptor (NK1R) immunoreactivity was localized to neurons in the RVM. Four days after ipl injection of CFA, the number of NK1R-immunoreactive neurons in the RVM was increased by 30%, and there was a concomitant increase in NK1R-immunoreactive processes in CFA-treated rats. Although NK1R immunoreactivity was increased, tachykinin-1 receptor (Tacr1) mRNA was not increased in the RVM of CFA-treated rats. To assess changes in Sub P release, the number of RVM neurons that exhibited NK1R internalization was examined in saline- and CFA-treated rats following noxious heat stimulation of the hind paws. Only CFA-treated rats that experienced noxious heat stimulation exhibited a significant increase in the number of neurons showing NK1R internalization. These data suggest that tonic Sub P release is not increased as a simple consequence of peripheral inflammation, but that phasic or evoked release of Sub P in the RVM is increased in response to noxious peripheral stimulation in a persistent inflammatory state. These data support the proposal that an upregulation of the NK1R in the RVM, as well as enhanced release of Sub P following noxious stimulation, underlie the pronociceptive role of Sub P under conditions of persistent inflammatory injury.
Collapse
Affiliation(s)
- Marta V Hamity
- Department of Anesthesia, University of Iowa, Iowa City, Iowa, 52242
| | | | | |
Collapse
|
19
|
Hall JD, DeWitte C, Ness TJ, Robbins MT. Serotonin enhances urinary bladder nociceptive processing via a 5-HT3 receptor mechanism. Neurosci Lett 2015; 604:97-102. [PMID: 26247537 DOI: 10.1016/j.neulet.2015.07.048] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 07/30/2015] [Accepted: 07/31/2015] [Indexed: 12/15/2022]
Abstract
Serotonin from the descending pain modulatory pathway is critical to nociceptive processing. Its effects on pain modulation may either be inhibitory or facilitatory, depending on the type of pain and which receptors are involved. Little is known about the role of serotonergic systems in bladder nociceptive processing. These studies examined the effect of systemic administration of the serotonin precursor, 5-hydroxytryptophan (5-HTP), on normal bladder and somatic sensation in rats. ELISA was used to quantify peripheral and central changes in serotonin and its major metabolite following 5-HTP administration, and the potential role of the 5-HT3 receptor on changes in bladder sensation elicited by 5-HTP was investigated. 5-HTP produced bladder hypersensitivity and somatic analgesia. The pro-nociceptive effect of 5-HTP was attenuated by intrathecal, but not systemic, ondansetron. Peripheral increases in serotonin, its metabolism and rate of turnover were detectable within 30min of 5-HTP administration. Significant enhancement of serotonin metabolism was observed centrally. These findings suggest that 5-HTP increases serotonin, which may then affect descending facilitatory systems to produce bladder hypersensitivity via activation of spinal 5-HT3 receptors.
Collapse
Affiliation(s)
- Jason D Hall
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, 901 19th Street South, BMR2-Room 202, Birmingham, AL 35294, USA
| | - Cary DeWitte
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, 901 19th Street South, BMR2-Room 202, Birmingham, AL 35294, USA
| | - Timothy J Ness
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, 901 19th Street South, BMR2-Room 202, Birmingham, AL 35294, USA
| | - Meredith T Robbins
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, 901 19th Street South, BMR2-Room 202, Birmingham, AL 35294, USA.
| |
Collapse
|
20
|
Guo W, Miyoshi K, Dubner R, Gu M, Li M, Liu J, Yang J, Zou S, Ren K, Noguchi K, Wei F. Spinal 5-HT3 receptors mediate descending facilitation and contribute to behavioral hypersensitivity via a reciprocal neuron-glial signaling cascade. Mol Pain 2014; 10:35. [PMID: 24913307 PMCID: PMC4067691 DOI: 10.1186/1744-8069-10-35] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 05/30/2014] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND It has been recently recognized that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT3 receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT3 receptor and its contribution to facilitation of pain remain unclear. RESULTS In the present study, activation of spinal 5-HT3 receptors by intrathecal injection of a selective 5-HT3 receptor agonist SR 57227 induced spinal glial hyperactivity, neuronal hyperexcitability and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via the chemokine fractalkine, microglia to astrocyte signaling via cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of NMDA receptors in the spinal dorsal horn. Glial hyperactivation in spinal dorsal horn after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. CONCLUSIONS These findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neurons and glia.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Feng Wei
- Department of Neural and Pain Sciences, Dental School; Program in Neuroscience, University of Maryland, 650 W, Baltimore St, Baltimore, Maryland 21201, USA.
| |
Collapse
|
21
|
Abstract
PURPOSE OF REVIEW Chronic pain is an important public health problem that negatively impacts quality of life of affected individuals and exacts an enormous socio-economic cost. Currently available therapeutics provide inadequate management of pain in many patients. Acute pain states generally resolve in most patients. However, for reasons that are poorly understood, in some individuals, acute pain can transform to a chronic state. Our understanding of the risk factors that underlie the development of chronic pain is limited. Recent studies have suggested an important contribution of dysfunction in descending pain modulatory circuits to pain 'chronification'. Human studies provide insights into possible endogenous and exogenous factors that may promote the conversion of pain into a chronic condition. RECENT FINDINGS Descending pain modulatory systems have been studied and characterized in animal models. Human brain imaging techniques, deep brain stimulation and the mechanisms of action of drugs that are effective in the treatment of pain confirm the clinical relevance of top-down pain modulatory circuits. Growing evidence supports the concept that chronic pain is associated with a dysregulation in descending pain modulation. Disruption of the balance of descending modulatory circuits to favour facilitation may promote and maintain chronic pain. Recent findings suggest that diminished descending inhibition is likely to be an important element in determining whether pain may become chronic. This view is consistent with the clinical success of drugs that enhance spinal noradrenergic activity, such as serotonin/norepinephrine reuptake inhibitors (SNRIs), in the treatment of chronic pain states. Consistent with this concept, a robust descending inhibitory system may be normally engaged to protect against the development of chronic pain. Imaging studies show that higher cortical and subcortical centres that govern emotional, motivational and cognitive processes communicate directly with descending pain modulatory circuits providing a mechanistic basis to explain how exogenous factors can influence the expression of chronic pain in a susceptible individual. SUMMARY Preclinical studies coupled with clinical pharmacologic and neuroimaging investigations have advanced our understanding of brain circuits that modulate pain. Descending pain facilitatory and inhibitory circuits arising ultimately in the brainstem provide mechanisms that can be engaged to promote or protect against pain 'chronification'. These systems interact with higher centres, thus providing a means through which exogenous factors can influence the risk of pain chronification. A greater understanding of the role of descending pain modulation can lead to novel therapeutic directions aimed at normalizing aberrant processes that can lead to chronic pain.
Collapse
Affiliation(s)
- Michael H Ossipov
- Department of Pharmacology, Arizona Health Sciences Center, University of Arizona, Tucson, Arizona, USA
| | | | | |
Collapse
|
22
|
Lee HK, Ahmed MM, King KC, Miranpuri GS, Kahle KT, Resnick DK, Sun D. Persistent phosphorylation of NKCC1 and WNK1 in the epicenter of the spinal cord following contusion injury. Spine J 2014; 14:777-81. [PMID: 24239489 DOI: 10.1016/j.spinee.2013.06.100] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 03/19/2013] [Accepted: 06/29/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT NKCC1 regulates neuronal homeostasis of chloride ions and mediates GABAergic activities in nociceptive processing. WNK1 is an upstream regulator of NKCC1 and acts via SPAK (STE20/SPS1-related proline/alanine-rich kinase) and oxidative stress-responsive kinase 1. NKCC1 activity has been shown to be important in edema formation and nociception following spinal cord injury (SCI). PURPOSE To determine the role of NKCC1 and WNK1 in spinal cord tissues in the acute and chronic phases following contusional SCI. STUDY DESIGN An experimental study investigating the phosphorylation profile of an important Cl-regulatory protein Na+-K+-Cl- cotransporter 1 (NKCC1) and its regulatory-kinase WNK1 (kinase with-no-lysine). METHODS Sprague-Dawley rats underwent a contusive SCI at T9. The epicenter spinal cord tissues were harvested at Days 1, 3, and 7 for acute phase of injury or Days 35 and 42 in the chronic phase of injury. Western blot was used to compare phosphorylated levels of both NKCC1 and WNK1 in injured tissues compared with those of sham. RESULTS A sustained increase in phosphorylation of NKCC1 and WNK1 was detected in the lesion epicenter in spinal cord during both acute and chronic phases following SCI. CONCLUSIONS These results suggest that persistent activation of NKCC1 and WNK1 may play an important role in SCI.
Collapse
Affiliation(s)
- Hyun Kyung Lee
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA
| | - Mostafa M Ahmed
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA
| | - Kevin C King
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA
| | - Gurwattan S Miranpuri
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA
| | - Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Parkman St, Boston, MA 02114, USA
| | - Daniel K Resnick
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA.
| | - Dandan Sun
- Department of Neurosurgery, University of Wisconsin School of Medicine and Public Health, Box 8600 Clinical Science Center, 600 Highland Ave., Madison, WI 53792, USA; Waisman Center, 1500 Highland Ave, Madison, WI 53705, USA
| |
Collapse
|
23
|
Kim YS, Chu Y, Han L, Li M, Li Z, LaVinka PC, Sun S, Tang Z, Park K, Caterina MJ, Ren K, Dubner R, Wei F, Dong X. Central terminal sensitization of TRPV1 by descending serotonergic facilitation modulates chronic pain. Neuron 2014; 81:873-887. [PMID: 24462040 DOI: 10.1016/j.neuron.2013.12.011] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2013] [Indexed: 01/05/2023]
Abstract
The peripheral terminals of primary nociceptive neurons play an essential role in pain detection mediated by membrane receptors like TRPV1, a molecular sensor of heat and capsaicin. However, the contribution of central terminal TRPV1 in the dorsal horn to chronic pain has not been investigated directly. Combining primary sensory neuron-specific GCaMP3 imaging with a trigeminal neuropathic pain model, we detected robust neuronal hyperactivity in injured and uninjured nerves in the skin, soma in trigeminal ganglion, and central terminals in the spinal trigeminal nucleus. Extensive TRPV1 hyperactivity was observed in central terminals innervating all dorsal horn laminae. The central terminal TRPV1 sensitization was maintained by descending serotonergic (5-HT) input from the brainstem. Central blockade of TRPV1 or 5-HT/5-HT3A receptors attenuated central terminal sensitization, excitatory primary afferent inputs, and mechanical hyperalgesia in the territories of injured and uninjured nerves. Our results reveal central mechanisms facilitating central terminal sensitization underlying chronic pain.
Collapse
Affiliation(s)
- Yu Shin Kim
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yuxia Chu
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201
| | - Liang Han
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Man Li
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201.,Department of Anesthesiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhe Li
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Pamela Colleen LaVinka
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shuohao Sun
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | | | - Kyoungsook Park
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Michael J Caterina
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Biological Chemistry, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ke Ren
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201
| | - Ronald Dubner
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201
| | - Feng Wei
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201
| | - Xinzhong Dong
- Department of Neuroscience, Center of Sensory Biology, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Howard Hughes Medical Institute, the Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| |
Collapse
|
24
|
Kang Y, Zhao Y, Guo R, Zhang M, Wang Y, Mu Y, Wu A, Yue Y, Wu J, Wang Y. Activation of ERK signaling in rostral ventromedial medulla is dependent on afferent input from dorsal column pathway and contributes to acetic acid-induced visceral nociception. Neurochem Int 2013; 63:389-96. [DOI: 10.1016/j.neuint.2013.07.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/26/2013] [Accepted: 07/13/2013] [Indexed: 12/30/2022]
|
25
|
Zhu Y, Zhang XL, Gold MS. Activity-dependent hyperpolarization of EGABA is absent in cutaneous DRG neurons from inflamed rats. Neuroscience 2013; 256:1-9. [PMID: 24135545 DOI: 10.1016/j.neuroscience.2013.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 12/22/2022]
Abstract
A shift in GABA(A) signaling from inhibition to excitation in primary afferent neurons appears to contribute to the inflammation-induced increase in afferent input to the CNS. An activity-dependent depolarization of the GABA(A) current equilibrium potential (E(GABA)) has been described in CNS neurons which drives a shift in GABA(A) signaling from inhibition to excitation. The purpose of the present study was to determine if such an activity-dependent depolarization of E(GABA) occurs in primary afferents and whether the depolarization is amplified with persistent inflammation. Acutely dissociated retrogradely labeled cutaneous dorsal root ganglion (DRG) neurons from naïve and inflamed rats were studied with gramicidin perforated patch recording. Rather than a depolarization, 200 action potentials delivered at 2 Hz resulted in a ∼10 mV hyperpolarization of E(GABA) in cutaneous neurons from naïve rats. No such hyperpolarization was observed in neurons from inflamed rats. The shift in E(GABA) was not blocked by 10 μM bumetanide. Furthermore, because activity-dependent hyperpolarization of E(GABA) was fully manifest in the absence of HCO₃⁻ in the bath solution, this shift was not dependent on a change in HCO₃⁻-Cl⁻ exchanger activity, despite evidence of HCO₃⁻-Cl⁻ exchangers in DRG neurons that may contribute to the establishment of E(GABA) in the presence of HCO₃⁻. While the mechanism underlying the activity-dependent hyperpolarization of E(GABA) has yet to be identified, because this mechanism appears to function as a form of feedback inhibition, facilitating GABA-mediated inhibition of afferent activity, it may serve as a novel target for the treatment of inflammatory pain.
Collapse
Affiliation(s)
- Y Zhu
- Department of Neural and Pain Sciences, University of Maryland, Baltimore School of Dentistry, Baltimore, MD, USA; Department of Anesthesiology, Division of Gastroenterology Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA
| | - X-L Zhang
- Department of Anesthesiology, Division of Gastroenterology Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA; Department of Pharmacology and Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - M S Gold
- Department of Anesthesiology, Division of Gastroenterology Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA; Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA; Department of Medicine, Division of Gastroenterology Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA; Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
26
|
Khasabov SG, Simone DA. Loss of neurons in rostral ventromedial medulla that express neurokinin-1 receptors decreases the development of hyperalgesia. Neuroscience 2013; 250:151-65. [PMID: 23831426 PMCID: PMC3769426 DOI: 10.1016/j.neuroscience.2013.06.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/22/2013] [Accepted: 06/25/2013] [Indexed: 12/22/2022]
Abstract
It is well known that neurons in the rostral ventromedial medulla (RVM) are involved in descending modulation of nociceptive transmission in the spinal cord. It has been shown that activation of neurokinin-1 receptors (NK-1Rs) in the RVM, which are presumably located on pain facilitating ON cells, produces hyperalgesia whereas blockade of NK-1Rs attenuates hyperalgesia. To obtain a better understanding of the functions of NK-1R expressing neurons in the RVM, we selectively ablated these neurons by injecting the stable analog of substance P (SP), Sar(9),Met(O2)(11)-Substance P, conjugated to the ribosomal toxin saporin (SSP-SAP) into the RVM. Rats received injections of SSP-SAP (1 μM) or an equal volume of 1 μM of saporin conjugated to artificial peptide (Blank-SAP). Stereological analysis of NK-1R- and NeuN-labeled neurons in the RVM was determined 21-24 days after treatment. Withdrawal responses to mechanical and heat stimuli applied to the plantar hindpaw were determined 5-28 days after treatment. Withdrawal responses were also determined before and after intraplantar injection of capsaicin (acute hyperalgesia) or complete Freund's adjuvant (CFA) (prolonged hyperalgesia). The proportion of NK-1R-labeled neurons in the RVM was 8.8 ± 1.3% in naïve rats and 8.1 ± 0.8% in rats treated with Blank-SAP. However, injection of SSP-SAP into the RVM resulted in a 90% decrease in NK-1R-labeled neurons. SSP-SAP did not alter withdrawal responses to mechanical or heat stimuli under normal conditions, and did not alter analgesia produced by morphine administered into the RVM. In contrast, the duration of nocifensive behaviors produced by capsaicin and mechanical and heat hyperalgesia produced by capsaicin and CFA were decreased in rats pretreated with SSP-SAP as compared to those that received Blank-SAP. These data support our earlier studies using NK-1R antagonists in the RVM and demonstrate that RVM neurons that possess the NK-1R do not play a significant role in modulating acute pain or morphine analgesia, but rather are involved in pain facilitation and the development and maintenance of hyperalgesia.
Collapse
Affiliation(s)
- S G Khasabov
- Department of Diagnostic & Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | | |
Collapse
|
27
|
Pinto-Ribeiro F, Amorim D, David-Pereira A, Monteiro AM, Costa P, Pertovaara A, Almeida A. Pronociception from the dorsomedial nucleus of the hypothalamus is mediated by the rostral ventromedial medulla in healthy controls but is absent in arthritic animals. Brain Res Bull 2013; 99:100-8. [PMID: 24121166 DOI: 10.1016/j.brainresbull.2013.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 09/27/2013] [Accepted: 10/01/2013] [Indexed: 12/23/2022]
Abstract
The dorsomedial nucleus of the hypothalamus (DMH) has been proposed to participate in stress-induced hyperalgesia through facilitation of pronociceptive cells in the rostroventromedial medulla (RVM). We hypothesized that the DMH participates in hyperalgesia induced by arthritis. The DMH was pharmacologically manipulated while assessing heat-evoked nociceptive behavior or the discharge rates of pronociceptive RVM ON- and antinociceptive RVM OFF-like cells in NAIVE, SHAM and monoarthritic (ARTH) animals. In NAIVE and SHAM animals, the changes in nociceptive behavior induced by activation of the DMH by glutamate and inhibition by lidocaine were in line with earlier evidence indicating that the DMH has a nociceptive facilitating role. However, in ARTH animals, neither activation nor inhibition of the DMH influenced pain-like behavior evoked by stimulation of an uninflamed skin region (paw and tail). In accordance with these behavioral results, activation or inhibition of the DMH induced pronociceptive changes in the discharge rates of RVM cells in NAIVE and SHAM animals, which suggests that the DMH has a pronociceptive role mediated by the RVM in normal animals. However, in ARTH animals, both glutamate and lidocaine in the DMH failed to influence either pain-like behavior or noxious stimulation-evoked responses of RVM cells, while blocking the DMH increased spontaneous activity in the pronociceptive RVM ON cells. Our data indicate that the DMH participates in descending facilitation of cutaneous nociception in healthy controls, but it is not engaged in the regulation of cutaneous nociception in monoarthritic animals, while a minor role in tonic suppression of nociception in arthritis cannot be discarded.
Collapse
Affiliation(s)
- Filipa Pinto-Ribeiro
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences (ECS), Campus of Gualtar, University of Minho, 4750-057 Braga, Portugal; ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | | | | | | | | | | | | |
Collapse
|
28
|
Chen T, Wang XL, Qu J, Wang W, Zhang T, Yanagawa Y, Wu SX, Li YQ. Neurokinin-1 Receptor-Expressing Neurons That Contain Serotonin and Gamma-Aminobutyric Acid in the Rat Rostroventromedial Medulla Are Involved in Pain Processing. THE JOURNAL OF PAIN 2013; 14:778-92. [DOI: 10.1016/j.jpain.2013.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/24/2012] [Accepted: 02/06/2013] [Indexed: 01/22/2023]
|
29
|
Facial pain with localized and widespread manifestations: separate pathways of vulnerability. Pain 2013; 154:2335-2343. [PMID: 23867732 DOI: 10.1016/j.pain.2013.07.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 06/24/2013] [Accepted: 07/09/2013] [Indexed: 02/06/2023]
Abstract
Human association studies of common genetic polymorphisms have identified many loci that are associated with risk of complex diseases, although individual loci typically have small effects. However, by envisaging genetic associations in terms of cellular pathways, rather than any specific polymorphism, combined effects of many biologically relevant alleles can be detected. The effects are likely to be most apparent in investigations of phenotypically homogenous subtypes of complex diseases. We report findings from a case-control, genetic association study of relationships between 2925 single nucleotide polymorphisms (SNPs) and 2 subtypes of a commonly occurring chronic facial pain condition, temporomandibular disorder (TMD): 1) localized TMD and 2) TMD with widespread pain. When compared to healthy controls, cases with localized TMD differed in allelic frequency of SNPs that mapped to a serotonergic receptor pathway (P=0.0012), while cases of TMD with widespread pain differed in allelic frequency of SNPs that mapped to a T-cell receptor pathway (P=0.0014). A risk index representing combined effects of 6 SNPs from the serotonergic pathway was associated with greater odds of localized TMD (odds ratio 2.7, P=1.3 E-09), and the result was reproduced in a replication case-control cohort study of 639 people (odds ratio 1.6, P=0.014). A risk index representing combined effects of 8 SNPs from the T-cell receptor pathway was associated with greater odds of TMD with widespread pain (P=1.9 E-08), although the result was not significant in the replication cohort. These findings illustrate potential for clinical classification of chronic pain based on distinct molecular profiles and genetic background.
Collapse
|
30
|
Teodoro FC, Tronco Júnior MF, Zampronio AR, Martini AC, Rae GA, Chichorro JG. Peripheral substance P and neurokinin-1 receptors have a role in inflammatory and neuropathic orofacial pain models. Neuropeptides 2013. [PMID: 23177733 DOI: 10.1016/j.npep.2012.10.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is accumulating evidence that substance P released from peripheral sensory neurons participates in inflammatory and neuropathic pain. In this study it was investigated the ability of substance P to induce orofacial nociception and thermal and mechanical hyperalgesia, as well as the role of NK1 receptors on models of orofacial inflammatory and neuropathic pain. Substance P injected into the upper lip at 1, 10 and 100 μg/50 μL failed to induce nociceptive behavior. Also, substance P (0.1-10 μg/50 μL) injected into the upper lip did not evoke orofacial cold hyperalgesia and when injected at 1 μg/50 μL did not induce mechanical hyperalgesia. However, substance P at this latter dose induced orofacial heat hyperalgesia, which was reduced by the pre-treatment of rats with a non-peptide NK1 receptor antagonist (SR140333B, 3mg/kg). Systemic treatment with SR140333B (3 mg/kg) also reduced carrageenan-induced heat hyperalgesia, but did not exert any influence on carrageenan-induced cold hyperalgesia. Blockade of NK1 receptors with SR140333B also reduced by about 50% both phases of the formalin response evaluated in the orofacial region. Moreover, heat, but not cold or mechanical, hyperalgesia induced by constriction of the infraorbital nerve, a model of trigeminal neuropathic pain, was abolished by pretreatment with SR140333B. Considering that substance P was peripherally injected (i.e. upper lip) and the NK1 antagonist used lacks the ability to cross the blood-brain-barrier, our results demonstrate that the peripheral SP/NK1 system participates in the heat hyperalgesia associated with inflammation or nerve injury and in the persistent pain evoked by formalin in the orofacial region.
Collapse
Affiliation(s)
- Fernanda C Teodoro
- Department of Pharmacology, Federal University of Parana, Curitiba, PR, Brazil
| | | | | | | | | | | |
Collapse
|
31
|
Cleary DR, Heinricher MM. Adaptations in responsiveness of brainstem pain-modulating neurons in acute compared with chronic inflammation. Pain 2013; 154:845-55. [PMID: 23588008 PMCID: PMC3661698 DOI: 10.1016/j.pain.2013.02.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 01/15/2013] [Accepted: 02/19/2013] [Indexed: 12/23/2022]
Abstract
Despite similar behavioral hypersensitivity, acute and chronic pain have distinct neural bases. We used intraplantar injection of complete Freund's adjuvant to directly compare activity of pain-modulating neurons in the rostral ventromedial medulla (RVM) in acute vs chronic inflammation. Heat-evoked and von Frey-evoked withdrawal reflexes and corresponding RVM neuronal activity were recorded in lightly anesthetized animals either during the first hour after complete Freund's adjuvant injection (acute) or 3 to 10 days later (chronic). Thermal and modest mechanical hyperalgesia during acute inflammation were associated with increases in the spontaneous activity of pain-facilitating ON-cells and suppression of pain-inhibiting OFF-cells. Acute hyperalgesia was reversed by RVM block, showing that the increased activity of RVM ON-cells is necessary for acute behavioral hypersensitivity. In chronic inflammation, thermal hyperalgesia had resolved but mechanical hyperalgesia had become pronounced. The spontaneous discharges of ON- and OFF-cells were not different from those in control subjects, but the mechanical response thresholds for both cell classes were reduced into the innocuous range. RVM block in the chronic condition worsened mechanical hyperalgesia. These studies identify distinct contributions of RVM ON- and OFF-cells to acute and chronic inflammatory hyperalgesia. During early immune-mediated inflammation, ON-cell spontaneous activity promotes hyperalgesia. After inflammation is established, the antinociceptive influence of OFF-cells is dominant, yet the lowered threshold for the OFF-cell pause allows behavioral responses to stimuli that would normally be considered innocuous. The efficacy of OFF-cells in counteracting sensitization of ascending transmission pathways could therefore be an important determining factor in development of chronic inflammatory pain.
Collapse
Affiliation(s)
- Daniel R Cleary
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA.
| | | |
Collapse
|
32
|
Zhang RX, Yan XB, Gu YH, Huang D, Gan L, Han R, Huang LH. Gene silencing of NR2B-containing NMDA receptor by intrathecal injection of short hairpin RNA reduces formalin-induced nociception in C57BL/6 mouse. Int J Neurosci 2013; 123:650-6. [PMID: 23528046 DOI: 10.3109/00207454.2013.789873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Spinal NR2B-containing N-methyl-D-aspartate receptors (NR2B) play a critical role in the formation of central sensitization and persistent pain. Previous studies show that gene silencing of the spinal NR2B subunit by small interfering RNA (siRNA) could alleviate nociception in animals. The siRNA is a 19- to 23-nt RNA duplex, which can be synthesized in vitro or derived from short hairpin RNAs (shRNAs). In the present study, we investigated whether intrathecal injection of shRNAs targeting NR2B (GRIN2B shRNA) could affect nociception on formalin-induced pain in mice. Our results showed that intrathecal injection of GRIN2B shRNA could decrease NR2B mRNA and protein expression levels and hence effectively relieve formalin-induced nociception in mice, suggesting that intrathecal delivery of GRIN2B shRNA can be an efficient way to silence the target gene and provide new insights into the treatment of chronic pain.
Collapse
Affiliation(s)
- Rao-Xiang Zhang
- Department of Anesthesiology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | | | | | | | | | | | | |
Collapse
|
33
|
Okubo M, Castro A, Guo W, Zou S, Ren K, Wei F, Keller A, Dubner R. Transition to persistent orofacial pain after nerve injury involves supraspinal serotonin mechanisms. J Neurosci 2013; 33:5152-61. [PMID: 23516281 PMCID: PMC3640487 DOI: 10.1523/jneurosci.3390-12.2013] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The orofacial region is a major focus of chronic neuropathic pain conditions characterized by primary hyperalgesia at the site of injury and secondary hyperalgesia outside the injured zone. We have used a rat model of injury to the maxillary branch (V2) of the trigeminal nerve to produce constant and long-lasting primary hyperalgesia in the V2 territory and secondary hyperalgesia in territories innervated by the mandibular branch (V3). Our findings indicate that the induction of primary and secondary hyperalgesia depended on peripheral input from the injured nerve. In contrast, the maintenance of secondary hyperalgesia depended on central mechanisms. The centralization of the secondary hyperalgesia involved descending 5-HT drive from the rostral ventromedial medulla and the contribution of 5-HT3 receptors in the trigeminal nucleus caudalis (Vc), the homolog of the spinal dorsal horn. Electrophysiological studies further indicate that after nerve injury spontaneous responses and enhanced poststimulus discharges in Vc nociresponsive neurons were time-dependent on descending 5-HT drive and peripheral input. The induction phase of secondary hyperalgesia involved central sensitization mechanisms in Vc neurons that were dependent on peripheral input, whereas the maintenance phase of secondary hyperalgesia involved central sensitization in Vc neurons conducted by a delayed descending 5-HT drive and a persistence of peripheral inputs. Our results are the first to show that the maintenance of secondary hyperalgesia and underlying central sensitization associated with persistent pain depend on a transition to supraspinal mechanisms involving the serotonin system in rostral ventromedial medulla-dorsal horn circuits.
Collapse
Affiliation(s)
| | - Alberto Castro
- 2Department of Anatomy and Neurobiology, Medical School; Program in Neuroscience, University of Maryland, Baltimore, Maryland 21201
| | - Wei Guo
- 1Department of Neural and Pain Sciences, Dental School and
| | - Shiping Zou
- 1Department of Neural and Pain Sciences, Dental School and
| | - Ke Ren
- 1Department of Neural and Pain Sciences, Dental School and
| | - Feng Wei
- 1Department of Neural and Pain Sciences, Dental School and
| | - Asaf Keller
- 2Department of Anatomy and Neurobiology, Medical School; Program in Neuroscience, University of Maryland, Baltimore, Maryland 21201
| | - Ronald Dubner
- 1Department of Neural and Pain Sciences, Dental School and
| |
Collapse
|
34
|
Khasabov SG, Brink TS, Schupp M, Noack J, Simone DA. Changes in response properties of rostral ventromedial medulla neurons during prolonged inflammation: modulation by neurokinin-1 receptors. Neuroscience 2012; 224:235-48. [PMID: 22917610 PMCID: PMC3498481 DOI: 10.1016/j.neuroscience.2012.08.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/10/2012] [Accepted: 08/14/2012] [Indexed: 01/05/2023]
Abstract
Activation of neurokinin-1 (NK-1) receptors in the rostral ventromedial medulla (RVM) can facilitate pain transmission in conditions such as inflammation, and thereby contribute to hyperalgesia. Since blockade of NK-1 receptors in the RVM can attenuate hyperalgesia produced by prolonged inflammation, we examined the role of NK-1 receptors in changes of response properties of RVM neurons following four days of hind paw inflammation with complete Freund's adjuvant. Recordings were made from functionally identified ON, OFF and NEUTRAL cells in the RVM. Spontaneous activity and responses evoked by a series of mechanical (10, 15, 26, 60, 100, and 180 g) and heat (34-50 °C) stimuli applied to the inflamed and non-inflamed hind paws were determined before and at 15 and 60 min after injection of the NK-1-antagonist L-733,060 or vehicle into the RVM. Prolonged inflammation did not alter the proportions of functionally-identified ON, OFF and NEUTRAL cells. ON cells exhibited enhanced responses to mechanical (60-100g) and heat (48-50 °C) stimuli applied to the inflamed paw, which were attenuated by L-733,060 but not by vehicle. Inhibitory responses of OFF cells evoked by mechanical stimuli applied to the inflamed paw were also inhibited by L-733,060, but responses evoked by stimulation of the contralateral paw were increased. Heat-evoked responses of OFF cells were not altered by L-733,060. Also, neither L-733,060 nor vehicle altered spontaneous ongoing discharge rate of RVM neurons. These data indicate that NK-1 receptors modulate excitability of ON cells which contribute to both mechanical and heat hyperalgesia, whereas NK-1 modulation of OFF cells contributes to mechanical hyperalgesia during prolonged inflammation.
Collapse
Affiliation(s)
- S G Khasabov
- Department of Diagnostic & Biological Sciences, University of Minnesota, School of Dentistry, Minneapolis, MN 55455, United States
| | | | | | | | | |
Collapse
|
35
|
Chai B, Guo W, Wei F, Dubner R, Ren K. Trigeminal-rostral ventromedial medulla circuitry is involved in orofacial hyperalgesia contralateral to tissue injury. Mol Pain 2012; 8:78. [PMID: 23092240 PMCID: PMC3484042 DOI: 10.1186/1744-8069-8-78] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/16/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Our previous studies have shown that complete Freund's adjuvant (CFA)-induced masseter inflammation and microinjection of the pro-inflammatory cytokine interleukin-1β (IL-1β) into the subnucleus interpolaris/subnucleus caudalis transition zone of the spinal trigeminal nucleus (Vi/Vc) can induce contralateral orofacial hyperalgesia in rat models. We have also shown that contralateral hyperalgesia is attenuated with a lesion of the rostral ventromedial medulla (RVM), a critical site of descending pain modulation. Here we investigated the involvement of the RVM-Vi/Vc circuitry in mediating contralateral orofacial hyperalgesia after an injection of CFA into the masseter muscle. RESULTS Microinjection of the IL-1 receptor antagonist (5 nmol, n=6) into the ipsilateral Vi/Vc attenuated the CFA-induced contralateral hyperalgesia but not the ipsilateral hyperalgesia. Intra-RVM post-treatment injection of the NK1 receptor antagonists, RP67580 (0.5-11.4 nmol) and L-733,060 (0.5-11.4 nmol), attenuated CFA-induced bilateral hyperalgesia and IL-1β induced bilateral hyperalgesia. Serotonin depletion in RVM neurons prior to intra-masseter CFA injection prevented the development of contralateral hyperalgesia 1-3 days after CFA injection. Inhibition of 5-HT(3) receptors in the contralateral Vi/Vc with direct microinjection of the select 5-HT(3) receptor antagonist, Y-25130 (2.6-12.9 nmol), attenuated CFA-induced contralateral hyperalgesia. Lesions to the ipsilateral Vc prevented the development of ipsilateral hyperalgesia but did not prevent the development of contralateral hyperalgesia. CONCLUSIONS These results suggest that the development of CFA-induced contralateral orofacial hyperalgesia is mediated through descending facilitatory mechanisms of the RVM-Vi/Vc circuitry.
Collapse
Affiliation(s)
- Bryan Chai
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
- Program in Neuroscience, University of Maryland, Baltimore, MD, 21201, USA
| | - Wei Guo
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
- Program in Neuroscience, University of Maryland, Baltimore, MD, 21201, USA
| | - Feng Wei
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
- Program in Neuroscience, University of Maryland, Baltimore, MD, 21201, USA
| | - Ronald Dubner
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
- Program in Neuroscience, University of Maryland, Baltimore, MD, 21201, USA
| | - Ke Ren
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA
- Program in Neuroscience, University of Maryland, Baltimore, MD, 21201, USA
| |
Collapse
|
36
|
Zhu Y, Lu S, Gold MS. Persistent inflammation increases GABA-induced depolarization of rat cutaneous dorsal root ganglion neurons in vitro. Neuroscience 2012; 220:330-40. [PMID: 22728089 PMCID: PMC3412885 DOI: 10.1016/j.neuroscience.2012.06.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/07/2012] [Accepted: 06/09/2012] [Indexed: 11/18/2022]
Abstract
Persistent inflammation is associated with a shift in spinal GABA(A) signaling from inhibition to excitation such that GABA(A)-receptor activation contributes to inflammatory hyperalgesia. We tested the hypothesis that the primary afferent is the site of the persistent inflammation-induced shift in GABA(A) signaling which is due to a Na(+)-K(+)-Cl(-)-co-transporter (NKCC1)-dependent depolarization of the GABA(A) current equilibrium potential (E(GABA)). Acutely dissociated retrogradely labeled cutaneous dorsal root ganglion (DRG) neurons from naïve and inflamed (3 days after a subcutaneous injection of complete Freund's adjuvant) adult male rats were studied with Ca(2+) imaging, western blot and gramicidin-perforated patch recording. GABA evoked a Ca(2+) transient in a subpopulation of small- to medium-diameter capsaicin-sensitive cutaneous neurons. Inflammation was associated with a significant increase in the magnitude of GABA-induced depolarization as well as the percentage of neurons in which GABA evoked a Ca(2+) transient. There was no detectable change in NKCC1 protein or phosphoprotein at the whole ganglia level. Furthermore, the increase in excitatory response was comparable in both HEPES- and HCO(3)(-)-buffered solutions, but was only associated with a depolarization of E(GABA) in HCO(3)(-)-based solution. In contrast, under both recording conditions, the excitatory response was associated with an increase in GABA(A) current density, a decrease in low threshold K(+) current density, and resting membrane potential depolarization. Our results suggest that increasing K(+) conductance in afferents innervating a site of persistent inflammation may have greater efficacy in the inhibition of inflammatory hyperalgesia than attempting to drive a hyperpolarizing shift in E(GABA).
Collapse
Affiliation(s)
- Yi Zhu
- Dept of Neural and Pain Sciences, University of Maryland, Baltimore School of Dentistry, Baltimore, Maryland
- Dept of Anesthesiology, University of Pittsburgh, Pittsburgh, USA
| | - Shaogang Lu
- Dept of Medicine (Division of Gastroenterology Hepatology and Nutrition), University of Pittsburgh, Pittsburgh, USA
| | - Michael S. Gold
- Dept of Anesthesiology, University of Pittsburgh, Pittsburgh, USA
- Dept of Neurobiology, University of Pittsburgh, Pittsburgh, USA
- Dept of Medicine (Division of Gastroenterology Hepatology and Nutrition), University of Pittsburgh, Pittsburgh, USA
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, USA
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, USA
| |
Collapse
|
37
|
Role of peripheral and spinal 5-HT3 receptors in development and maintenance of formalin-induced long-term secondary allodynia and hyperalgesia. Pharmacol Biochem Behav 2012; 101:246-57. [DOI: 10.1016/j.pbb.2012.01.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 01/13/2012] [Accepted: 01/16/2012] [Indexed: 12/19/2022]
|
38
|
Meng QW, Xu SC. Advances in research of esophageal visceral hypersensitivity. Shijie Huaren Xiaohua Zazhi 2012; 20:568-573. [DOI: 10.11569/wcjd.v20.i7.568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gastroesophageal reflux disease (GERD) is a common disorder that is often associated with unpleasant symptoms requiring utilization of health care resource. Both animal and clinical studies suggest that a variety of receptors on afferent nerves sensitized upon exposure to acid increase afferent input to the spinal cord dorsal horn neurons and lead to a reduction in threshold of these neurons together with an increase in their receptive field. This increased sensitivity of primary afferent nerves is described as peripheral sensitization, whereas the consequent increase in sensitivity of the spinal dorsal horn neurons is described as central sensitization. Once these mechanisms have been established, they can cause a long-term increase in sensitivity of tissues to previously innocuous stimuli. Furthermore, psychological stress and mechanical stimulation both have been shown to increase DIS and may therefore facilitate peripheral sensitization. Currently peripheral and central sensitizations are considered to be important mechanisms of esophageal pain hypersensitivity and occurrence of symptoms to even physiological amounts of acid. In these patients treatments aimed at reducing neuronal sensitivity may be effective. This article mainly focuses on the recent advances in research of esophageal visceral hypersensitivity.
Collapse
|
39
|
Larsson MBO, Tillisch K, Craig A(B, Engström M, Labus J, Naliboff B, Lundberg P, Ström M, Mayer EA, Walter SA. Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome. Gastroenterology 2012; 142:463-472.e3. [PMID: 22108191 PMCID: PMC3288538 DOI: 10.1053/j.gastro.2011.11.022] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 10/31/2011] [Accepted: 11/02/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Only a fraction of patients with irritable bowel syndrome (IBS) have increased perceptual sensitivity to rectal distension, indicating differences in processing and/or modulation of visceral afferent signals. We investigated the brain mechanisms of these perceptual differences. METHODS We analyzed data from 44 women with IBS and 20 female healthy subjects (controls). IBS symptom severity was determined by a severity scoring system. Anxiety and depression symptoms were assessed using the hospital anxiety and depression score. Blood oxygen level-dependent signals were measured by functional magnetic resonance imaging during expectation and delivery of high (45 mmHg) and low (15 mmHg) intensity rectal distensions. Perception thresholds to rectal distension were determined in the scanner. Brain imaging data were compared among 18 normosensitive and 15 hypersensitive patients with IBS and 18 controls. Results were reported significant if peak P-values were ≤.05, with family-wise error correction in regions of interest. RESULTS The subgroups of patients with IBS were similar in age, symptom duration, psychological symptoms, and IBS symptom severity. Although brain responses to distension were similar between normosensitive patients and controls, hypersensitive patients with IBS had greater activation of insula and reduced deactivation in pregenual anterior cingulate cortex during noxious rectal distensions, compared to controls and normosensitive patients with IBS. During expectation of rectal distension, normosensitive patients with IBS had more activation in right hippocampus than controls. CONCLUSIONS Despite similarities in symptoms, hyper- and normosensitive patients with IBS differ in cerebral responses to standardized rectal distensions and their expectation, consistent with differences in ascending visceral afferent input.
Collapse
Affiliation(s)
- MBO Larsson
- Department of Clinical and Experimental Medicine/Gastroenterology, Center for Medical Image Science and Visualization (CMIV), Linköping University; Department of Gastroenterology, UHL, County Council of Östergötland, Linköping, Sweden
| | - K Tillisch
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive, Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - A.D. (Bud) Craig
- Barrow Neurological Institute, Phoenix, AZ, USA; Visiting Professor at the Department of Clinical and Experimental Medicine, Linköping University, Sweden
| | - M Engström
- Department of Medical and Health Sciences (IMH)/Radiology, Linköping University, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Sweden
| | - J Labus
- Oppenheimer Family Center for Neurobiology of Stress, Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - B Naliboff
- Oppenheimer Family Center for Neurobiology of Stress, Department of Psychiatry, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - P Lundberg
- Center for Medical Image Science and Visualization, CMIV; Radiation Physics, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University; Department of Radiation Physics UHL, County Council of Östergötland, Linköping, Sweden; Center for Medical Image Science and Visualization, CMIV; Radiology, Department of Medical and Health Sciences, Faculty of Health Sciences, Linköping University; Department of Radiology UHL, County Council of Östergötland, Linköping, Sweden
| | - M Ström
- Department of Clinical and Experimental Medicine/Gastroenterology, Linköping University; Department of Gastroenterology, UHL, County Council of Östergötland, Linköping, Sweden
| | - EA Mayer
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - SA Walter
- Department of Clinical and Experimental Medicine/Gastroenterology, Center for Medical Image Science and Visualization (CMIV), Linköping University; Department of Gastroenterology, UHL, County Council of Östergötland, Linköping, Sweden
| |
Collapse
|
40
|
Tillisch K, Labus J, Nam B, Bueller J, Smith S, Suyenobu B, Siffert J, McKelvy J, Naliboff B, Mayer E. Neurokinin-1-receptor antagonism decreases anxiety and emotional arousal circuit response to noxious visceral distension in women with irritable bowel syndrome: a pilot study. Aliment Pharmacol Ther 2012; 35:360-7. [PMID: 22221140 PMCID: PMC4073664 DOI: 10.1111/j.1365-2036.2011.04958.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Irritable bowel syndrome is characterised by chronic abdominal pain and frequent comorbid anxiety. The substance P ⁄ neurokinin-1 receptor system is implicated in the regulation of both pain and anxiety, suggesting a potential therapeutic target in IBS. AIM To determine whether inhibition of the neurokinin-1 receptor (NK1R) will change pain ratings and brain responses to experimental visceral pain and anxiety symptoms in women with IBS or not. METHODS Rome II positive IBS women were recruited for a double-blind, placebo-controlled, cross-over study of NK1R antagonist AV608. Treatment periods were 3 weeks with a 2-week washout period. Functional MRI during a visceral distension paradigm was performed before first treatment and after treatment blocks. SPM8 was used to compare brain activity during painful and nonpainful visceral stimuli in regions associated with emotional arousal and interoception. Negative affect, anxiety symptoms and pain ratings were assessed. RESULTS Eleven subjects completed the study and eight subjects provided fMRI data. AV608, compared with placebo, was associated with reduced anxiety, negative affect, and pain ratings. During AV608 treatment, the amygdala, hippocampus and anterior cingulate gyrus showed decreased activity during visceral distension. AV608 was also associated with decreases in activity in brain regions associated with interoception (posterior insula, anterior mid-cingulate gyrus). CONCLUSIONS Chronic treatment with AV608 in IBS is associated with improved mood and pain ratings and activity of emotional arousal related brain regions. This suggests that further exploration of NK1R antagonists is warranted in visceral pain disorders, particularly in patients with comorbid anxiety symptoms.
Collapse
Affiliation(s)
- K Tillisch
- Center for Neurobiology of Stress, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Brink TS, Pacharinsak C, Khasabov SG, Beitz AJ, Simone DA. Differential modulation of neurons in the rostral ventromedial medulla by neurokinin-1 receptors. J Neurophysiol 2011; 107:1210-21. [PMID: 22031765 DOI: 10.1152/jn.00678.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The rostral ventromedial medulla (RVM) is part of descending circuitry that modulates nociceptive processing at the level of the spinal cord. RVM output can facilitate pain transmission under certain conditions such as inflammation, and thereby contribute to hyperalgesia. Evidence suggests that substance P and activation of neurokinin-1 (NK-1) receptors in the RVM are involved in descending facilitation of nociception. We showed previously that injection of NK-1 receptor antagonists into the RVM attenuated mechanical and heat hyperalgesia produced by intraplantar injection of capsaicin. Furthermore, intraplantar injection of capsaicin excited ON cells in the RVM and inhibited ongoing activity of OFF cells. In the present studies, we therefore examined changes in responses of RVM neurons to mechanical and heat stimuli after intraplantar injection of capsaicin and determined the role of NK-1 receptors by injecting a NK-1 receptor antagonist into the RVM prior to capsaicin. After capsaicin injection, excitatory responses of ON cells and inhibitory responses of OFF cells evoked by mechanical and heat stimuli applied to the injected, but not contralateral, paw were increased. Injection of the NK-1 antagonist L-733,060 did not alter evoked responses of ON or OFF cells but attenuated the capsaicin-evoked enhanced responses of ON cells to mechanical and heat stimuli with less of an effect on the enhanced inhibitory responses of OFF cells. These data support the notion that descending facilitation from RVM contributes to hyperalgesia and that NK-1 receptors, presumably located on ON cells, play an important role in initiating descending facilitation of nociceptive transmission.
Collapse
Affiliation(s)
- Thaddeus S Brink
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis 55455, USA
| | | | | | | | | |
Collapse
|
42
|
Yang K, Takeuchi K, Wei F, Dubner R, Ren K. Activation of group I mGlu receptors contributes to facilitation of NMDA receptor membrane current in spinal dorsal horn neurons after hind paw inflammation in rats. Eur J Pharmacol 2011; 670:509-18. [PMID: 21951968 DOI: 10.1016/j.ejphar.2011.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/10/2011] [Accepted: 09/10/2011] [Indexed: 10/17/2022]
Abstract
The interaction between the group I metabotropic glutamate (mGlu) receptors and N-methyl-D-aspartate (NMDA) receptors plays a critical role in spinal hyperexcitability and hyperalgesia. The cellular mechanisms underlying this interaction remain unknown. Utilizing an ex vivo spinal slice preparation from young adult rats, we investigated the group I mGlu receptor modulation of NMDA receptor-mediated current in superficial dorsal horn neurons by patch clamp recording after complete Freund's adjuvant (CFA)-induced hind paw inflammation. We show that NMDA receptor-mediated dorsal root stimulation-evoked EPSC (eEPSC) and NMDA-induced current was enhanced in the inflamed rats, compared to naïve rats and this effect was attenuated by AIDA (1 mM), a group I mGlu receptor antagonist. There were also increases in the frequency and amplitude of miniature excitatory postsynaptic currents in the presence of tetrodotoxin, suggesting enhanced presynaptic glutamate release probability and postsynaptic membrane responsiveness in inflamed rats. DHPG (10 μM), a selective group I mGlu receptor agonist, further facilitated NMDA receptor-mediated eEPSC and NMDA-induced current in inflamed rats. The DHPG-produced facilitation of NMDA-induced current was blocked by intracellular dialysis of GDP-beta-S (1 mM), a G protein antagonist, and BAPTA (15 mM), an intracellular calcium chelating agent; and by pretreatment with U73,122 (10 μM), a PLC inhibitor, or 2-APB (100 μM), an IP₃-receptor antagonist. These findings support the hypothesis that signal transduction coupling between group I mGlu receptors and NMDA receptors underlies the activation of NMDA receptors in spinal hyperexcitability and hyperalgesia.
Collapse
Affiliation(s)
- Kun Yang
- Department of Neural and Pain Sciences, School of Dentistry and Program in Neuroscience, University of Maryland, Baltimore, MD 21201, USA
| | | | | | | | | |
Collapse
|
43
|
Gu M, Miyoshi K, Dubner R, Guo W, Zou S, Ren K, Noguchi K, Wei F. Spinal 5-HT(3) receptor activation induces behavioral hypersensitivity via a neuronal-glial-neuronal signaling cascade. J Neurosci 2011; 31:12823-36. [PMID: 21900561 PMCID: PMC3199304 DOI: 10.1523/jneurosci.1564-11.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 07/15/2011] [Accepted: 07/18/2011] [Indexed: 01/15/2023] Open
Abstract
Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT(3) receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT(3) receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT(3) receptor by intrathecal injection of a selective 5-HT(3) receptor agonist, SR57227, induced spinal glial hyperactivity, neuronal hyperexcitability, and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via the cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous brain-derived neurotrophic factor-induced descending pain facilitation was accompanied by upregulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, and these events were significantly prevented by functional blockade of spinal 5-HT(3) receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia.
Collapse
Affiliation(s)
- Ming Gu
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| | - Kan Miyoshi
- Department of Anatomy and Neuroscience, Institute for Advanced Medical Sciences, Hyogo University, Hyogo 663-8501, Japan
| | - Ronald Dubner
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| | - Wei Guo
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| | - Shiping Zou
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| | - Ke Ren
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| | - Koichi Noguchi
- Department of Anatomy and Neuroscience, Institute for Advanced Medical Sciences, Hyogo University, Hyogo 663-8501, Japan
| | - Feng Wei
- Department of Neural and Pain Sciences, Program in Neuroscience, Dental School, University of Maryland, Baltimore, Maryland 21201 and
| |
Collapse
|