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Kim S, Barry DM, Liu XY, Yin S, Munanairi A, Meng QT, Cheng W, Mo P, Wan L, Liu SB, Ratnayake K, Zhao ZQ, Gautam N, Zheng J, Karunarathne WKA, Chen ZF. Facilitation of TRPV4 by TRPV1 is required for itch transmission in some sensory neuron populations. Sci Signal 2016; 9:ra71. [PMID: 27436359 DOI: 10.1126/scisignal.aaf1047] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The transient receptor potential channels (TRPs) respond to chemical irritants and temperature. TRPV1 responds to the itch-inducing endogenous signal histamine, and TRPA1 responds to the itch-inducing chemical chloroquine. We showed that, in sensory neurons, TRPV4 is important for both chloroquine- and histamine-induced itch and that TRPV1 has a role in chloroquine-induced itch. Chloroquine-induced scratching was reduced in mice in which TRPV1 was knocked down or pharmacologically inhibited. Both TRPV4 and TRPV1 were present in some sensory neurons. Pharmacological blockade of either TRPV4 or TRPV1 significantly attenuated the Ca(2+) response of sensory neurons exposed to histamine or chloroquine. Knockout of Trpv1 impaired Ca(2+) responses and reduced scratching behavior evoked by a TRPV4 agonist, whereas knockout of Trpv4 did not alter TRPV1-mediated capsaicin responses. Electrophysiological analysis of human embryonic kidney (HEK) 293 cells coexpressing TRPV4 and TRPV1 revealed that the presence of both channels enhanced the activation kinetics of TRPV4 but not of TRPV1. Biochemical and biophysical studies suggested a close proximity between TRPV4 and TRPV1 in dorsal root ganglion neurons and in cultured cells. Thus, our studies identified TRPV4 as a channel that contributes to both histamine- and chloroquine-induced itch and indicated that the function of TRPV4 in itch signaling involves TRPV1-mediated facilitation. TRP facilitation through the formation of heteromeric complexes could be a prevalent mechanism by which the vast array of somatosensory information is encoded in sensory neurons.
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Affiliation(s)
- Seungil Kim
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Devin M Barry
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xian-Yu Liu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shijin Yin
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Admire Munanairi
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Qing-Tao Meng
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Wei Cheng
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian 116044, P.R. China
| | - Ping Mo
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Nanhai Hospital of Southern Medical University, Foshan 528000, P.R. China
| | - Li Wan
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shen-Bin Liu
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - Zhong-Qiu Zhao
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Narasimhan Gautam
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jie Zheng
- Department of Physiology and Membrane Biology, University of California School of Medicine, Davis, CA 95616, USA
| | | | - Zhou-Feng Chen
- Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA. Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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202
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Guo W, Chu YX, Imai S, Yang JL, Zou S, Mohammad Z, Wei F, Dubner R, Ren K. Further observations on the behavioral and neural effects of bone marrow stromal cells in rodent pain models. Mol Pain 2016; 12:12/0/1744806916658043. [PMID: 27329776 PMCID: PMC4956005 DOI: 10.1177/1744806916658043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Bone marrow stromal cells (BMSCs) have shown potential to treat chronic pain, although much still needs to be learned about their efficacy and mechanisms of action under different pain conditions. Here, we provide further convergent evidence on the effects of BMSCs in rodent pain models. RESULTS In an orofacial pain model involving injury of a tendon of the masseter muscle, BMSCs attenuated behavioral pain conditions assessed by von Frey filaments and a conditioned place avoidance test in female Sprague-Dawley rats. The antihyperalgesia of BMSCs in females lasted for <8 weeks, which is shorter than that seen in males. To relate preclinical findings to human clinical conditions, we used human BMSCs. Human BMSCs (1.5 M cells, i.v.) attenuated mechanical and thermal hyperalgesia induced by spinal nerve ligation and suppressed spinal nerve ligation-induced aversive behavior, and the effect persisted through the 8-week observation period. In a trigeminal slice preparation, BMSC-treated and nerve-injured C57B/L mice showed reduced amplitude and frequency of spontaneous excitatory postsynaptic currents, as well as excitatory synaptic currents evoked by electrical stimulation of the trigeminal nerve root, suggesting inhibition of trigeminal neuronal hyperexcitability and primary afferent input by BMSCs. Finally, we observed that GluN2A (N-methyl-D-aspartate receptor subunit 2A) tyrosine phosphorylation and protein kinase Cgamma (PKCg) immunoreactivity in rostral ventromedial medulla was suppressed at 8 weeks after BMSC in tendon-injured rats. CONCLUSIONS Collectively, the present work adds convergent evidence supporting the use of BMSCs in pain control. As PKCg activity related to N-methyl-D-aspartate receptor activation is critical in opioid tolerance, these results help to understand the mechanisms of BMSC-produced long-term antihyperalgesia, which requires opioid receptors in rostral ventromedial medulla and apparently lacks the development of tolerance.
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Affiliation(s)
- Wei Guo
- University of Maryland School of Denstistry
| | - Yu-Xia Chu
- University of Maryland School of DenstistryUniversity of Maryland School of DentistryUniversity of Maryland School of DentristryUniversity of Maryland School of DentistryUniversity of Maryland School of Dentistry
| | - Satoshi Imai
- University of Maryland School of DenstistryUniversity of Maryland School of DentistryUniversity of Maryland School of DentristryUniversity of Maryland School of DentistryUniversity of Maryland School of Dentistry
| | | | | | | | - Feng Wei
- University of Maryland School of DenstistryUniversity of Maryland School of DentistryUniversity of Maryland School of DentristryUniversity of Maryland School of DentistryUniversity of Maryland School of Dentistry
| | | | - Ke Ren
- University of Maryland School of DenstistryUniversity of Maryland School of DentistryUniversity of Maryland School of DentristryUniversity of Maryland School of DentistryUniversity of Maryland School of Dentistry
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203
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Malek N, Kostrzewa M, Makuch W, Pajak A, Kucharczyk M, Piscitelli F, Przewlocka B, Di Marzo V, Starowicz K. The multiplicity of spinal AA-5-HT anti-nociceptive action in a rat model of neuropathic pain. Pharmacol Res 2016; 111:251-263. [PMID: 27326920 DOI: 10.1016/j.phrs.2016.06.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/25/2016] [Accepted: 06/11/2016] [Indexed: 11/27/2022]
Abstract
There is considerable evidence to support the role of anandamide (AEA), an endogenous ligand of cannabinoid receptors, in neuropathic pain modulation. AEA also produces effects mediated by other biological targets, of which the transient receptor potential vanilloid type 1 (TRPV1) has been the most investigated. Both, inhibition of AEA breakdown by fatty acid amide hydrolase (FAAH) and blockage of TRPV1 have been shown to produce anti-nociceptive effects. Recent research suggests the usefulness of dual-action compounds, which may afford greater anti-allodynic efficacy. Therefore, in the present study, we examined the effect of N-arachidonoyl-serotonin (AA-5-HT), a blocker of FAAH and TRPV1, in a rat model of neuropathic pain after intrathecal administration. We found that treatment with AA-5-HT increased the pain threshold to mechanical and thermal stimuli, with highest effect at the dose of 500nM, which was most strongly attenuated by AM-630, CB2 antagonist, administration. The single action blockers PF-3845 (1000nM, for FAAH) and I-RTX (1nM, for TRPV1) showed lower efficacy than AA-5-HT. Moreover AA-5-HT (500nM) elevated AEA and palmitoylethanolamide (PEA) levels. Among the possible targets of these mediators, only the mRNA levels of CB2, GPR18 and GPR55, which are believed to be novel cannabinoid receptors, were upregulated in the spinal cord and/or DRG of CCI rats. It was previously reported that AA-5-HT acts in CB1 and TRPV1-dependent manner after systemic administration, but here for the first time we show that AA-5-HT action at the spinal level involves CB2, with potential contributions from GRP18 and/or GPR55 receptors.
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Affiliation(s)
- Natalia Malek
- Laboratory of Pain Pathophysiology, Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland; Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Magdalena Kostrzewa
- Laboratory of Pain Pathophysiology, Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland; Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Wioletta Makuch
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Agnieszka Pajak
- Laboratory of Pain Pathophysiology, Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland; Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Mateusz Kucharczyk
- Laboratory of Pain Pathophysiology, Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland; Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Fabiana Piscitelli
- Endocannabinoid Research Group, Institute of Biomolecular ChemistryC.N.R., Via Campi Flegrei 34, Comprensorio Olivetti, 80078 Pozzuoli (NA), Italy.
| | - Barbara Przewlocka
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
| | - Vincenzo Di Marzo
- Endocannabinoid Research Group, Institute of Biomolecular ChemistryC.N.R., Via Campi Flegrei 34, Comprensorio Olivetti, 80078 Pozzuoli (NA), Italy.
| | - Katarzyna Starowicz
- Laboratory of Pain Pathophysiology, Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland; Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12 Street, 31-343 Krakow, Poland.
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204
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Simultaneous optical and electrical in vivo analysis of the enteric nervous system. Nat Commun 2016; 7:11800. [PMID: 27270085 PMCID: PMC4899629 DOI: 10.1038/ncomms11800] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/28/2016] [Indexed: 01/16/2023] Open
Abstract
The enteric nervous system (ENS) is a major division of the nervous system and vital to the gastrointestinal (GI) tract and its communication with the rest of the body. Unlike the brain and spinal cord, relatively little is known about the ENS in part because of the inability to directly monitor its activity in live animals. Here, we integrate a transparent graphene sensor with a customized abdominal window for simultaneous optical and electrical recording of the ENS in vivo. The implanted device captures ENS responses to neurotransmitters, drugs and optogenetic manipulation in real time. The enteric nervous system (ENS) plays a key role in regulating gut motility and homeostasis yet it remains a challenging system to record from. Here, the authors develop a novel abdominal window permitting simultaneous optical and electrical recording of mouse ENS system activity over prolonged time periods.
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205
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Williams EK, Chang RB, Strochlic DE, Umans BD, Lowell BB, Liberles SD. Sensory Neurons that Detect Stretch and Nutrients in the Digestive System. Cell 2016; 166:209-21. [PMID: 27238020 DOI: 10.1016/j.cell.2016.05.011] [Citation(s) in RCA: 378] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 04/11/2016] [Accepted: 04/22/2016] [Indexed: 12/25/2022]
Abstract
Neural inputs from internal organs are essential for normal autonomic function. The vagus nerve is a key body-brain connection that monitors the digestive, cardiovascular, and respiratory systems. Within the gastrointestinal tract, vagal sensory neurons detect gut hormones and organ distension. Here, we investigate the molecular diversity of vagal sensory neurons and their roles in sensing gastrointestinal inputs. Genetic approaches allowed targeted investigation of gut-to-brain afferents involved in homeostatic responses to ingested nutrients (GPR65 neurons) and mechanical distension of the stomach and intestine (GLP1R neurons). Optogenetics, in vivo ganglion imaging, and genetically guided anatomical mapping provide direct links between neuron identity, peripheral anatomy, central anatomy, conduction velocity, response properties in vitro and in vivo, and physiological function. These studies clarify the roles of vagal afferents in mediating particular gut hormone responses. Moreover, genetic control over gut-to-brain neurons provides a molecular framework for understanding neural control of gastrointestinal physiology.
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Affiliation(s)
- Erika K Williams
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Rui B Chang
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - David E Strochlic
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Benjamin D Umans
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Stephen D Liberles
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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206
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Yu G, Yang N, Li F, Chen M, Guo CJ, Wang C, Hu D, Yang Y, Zhu C, Wang Z, Shi H, Gegen T, Tang M, He Q, Liu Q, Tang Z. Enhanced itch elicited by capsaicin in a chronic itch model. Mol Pain 2016; 12:12/0/1744806916645349. [PMID: 27118771 PMCID: PMC4956172 DOI: 10.1177/1744806916645349] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/20/2016] [Indexed: 11/17/2022] Open
Abstract
Chronic itch (pruritus) is an important clinical problem. However, the underlying molecular basis has yet to be understood. The Transient Receptor Potential Vanilloid 1 channel is a heat-sensitive cation channel expressed in primary sensory neurons and involved in both thermosensation and pain, but its role in chronic itch remains elusive. Here, we for the first time revealed an increased innervation density of Transient Receptor Potential Vanilloid 1-expressing sensory fibers in the skin afflicted with chronic itch. Further analysis indicated that this phenomenon is due to an expansion of Transient Receptor Potential Vanilloid 1-expressing sensory neurons under chronic itch conditions. As a functional correlates of this neuronal expansion, we observed an enhanced neuronal responsiveness to capsaicin under the dry skin conditions. Importantly, the neuronal hypersensitivity to capsaicin results in itch, rather than pain sensation, suggesting that the up-regulated Transient Receptor Potential Vanilloid 1 underlies the pain-to-itch switch under chronic itchy conditions. The study shows that there are different mechanisms of chronic pain and itching, and Transient Receptor Potential Vanilloid 1 plays an important role in chronic itch.
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Affiliation(s)
- Guang Yu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Niuniu Yang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Fengxian Li
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, China
| | - Meijuan Chen
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Changxiong J Guo
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Changming Wang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Danyou Hu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Yan Yang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Chan Zhu
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Zhongli Wang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Hao Shi
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Tana Gegen
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Ming Tang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Qian He
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
| | - Qin Liu
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Zongxiang Tang
- College of Basic Medicine, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China
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207
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Role of the RVM in Descending Pain Regulation Originating from the Cerebrospinal Fluid-Contacting Nucleus. Neurochem Res 2016; 41:1651-61. [DOI: 10.1007/s11064-016-1880-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/25/2016] [Accepted: 02/29/2016] [Indexed: 01/09/2023]
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208
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Kaji K, Shinoda M, Honda K, Unno S, Shimizu N, Iwata K. Connexin 43 contributes to ectopic orofacial pain following inferior alveolar nerve injury. Mol Pain 2016; 12:12/0/1744806916633704. [PMID: 27030716 PMCID: PMC4955997 DOI: 10.1177/1744806916633704] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Accepted: 12/29/2015] [Indexed: 12/22/2022] Open
Abstract
Background Clinically, it is well known that injury of mandibular nerve fiber induces persistent ectopic pain which can spread to a wide area of the orofacial region innervated by the uninjured trigeminal nerve branches. However, the exact mechanism of such persistent ectopic orofacial pain is not still known. The present study was undertaken to determine the role of connexin 43 in the trigeminal ganglion on mechanical hypersensitivity in rat whisker pad skin induced by inferior alveolar nerve injury. Here, we examined changes in orofacial mechanical sensitivity following inferior alveolar nerve injury. Furthermore, changes in connexin 43 expression in the trigeminal ganglion and its localization in the trigeminal ganglion were also examined. In addition, we investigated the functional significance of connexin 43 in relation to mechanical allodynia by using a selective gap junction blocker (Gap27). Results Long-lasting mechanical allodynia in the whisker pad skin and the upper eyelid skin, and activation of satellite glial cells in the trigeminal ganglion, were induced after inferior alveolar nerve injury. Connexin 43 was expressed in the activated satellite glial cells encircling trigeminal ganglion neurons innervating the whisker pad skin, and the connexin 43 protein expression was significantly increased after inferior alveolar nerve injury. Administration of Gap27 in the trigeminal ganglion significantly reduced satellite glial cell activation and mechanical hypersensitivity in the whisker pad skin. Moreover, the marked activation of satellite glial cells encircling trigeminal ganglion neurons innervating the whisker pad skin following inferior alveolar nerve injury implies that the satellite glial cell activation exerts a major influence on the excitability of nociceptive trigeminal ganglion neurons. Conclusions These findings indicate that the propagation of satellite glial cell activation throughout the trigeminal ganglion via gap junctions, which are composed of connexin 43, plays a pivotal role in ectopic mechanical hypersensitivity in whisker pad skin following inferior alveolar nerve injury.
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Affiliation(s)
- Kaori Kaji
- Department of Orthodontics, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
| | - Masamichi Shinoda
- Department of Physiology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
| | - Kuniya Honda
- Department of Physiology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
| | - Syumpei Unno
- Department of Physiology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
| | - Noriyoshi Shimizu
- Department of Orthodontics, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
| | - Koichi Iwata
- Department of Physiology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
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Patel R, Dickenson AH. Mechanisms of the gabapentinoids and α 2 δ-1 calcium channel subunit in neuropathic pain. Pharmacol Res Perspect 2016; 4:e00205. [PMID: 27069626 PMCID: PMC4804325 DOI: 10.1002/prp2.205] [Citation(s) in RCA: 161] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 11/17/2015] [Accepted: 11/19/2015] [Indexed: 12/18/2022] Open
Abstract
The gabapentinoid drugs gabapentin and pregabalin are key front‐line therapies for various neuropathies of peripheral and central origin. Originally designed as analogs of GABA, the gabapentinoids bind to the α2δ‐1 and α2δ‐2 auxiliary subunits of calcium channels, though only the former has been implicated in the development of neuropathy in animal models. Transgenic approaches also identify α2δ‐1 as key in mediating the analgesic effects of gabapentinoids, however the precise molecular mechanisms remain unclear. Here we review the current understanding of the pathophysiological role of the α2δ‐1 subunit, the mechanisms of analgesic action of gabapentinoid drugs and implications for efficacy in the clinic. Despite widespread use, the number needed to treat for gabapentin and pregabalin averages from 3 to 8 across neuropathies. The failure to treat large numbers of patients adequately necessitates a novel approach to treatment selection. Stratifying patients by sensory profiles may imply common underlying mechanisms, and a greater understanding of these mechanisms could lead to more direct targeting of gabapentinoids.
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Affiliation(s)
- Ryan Patel
- Department of Neuroscience, Physiology and Pharmacology University College London Gower Street London WC1E 6BT UK
| | - Anthony H Dickenson
- Department of Neuroscience, Physiology and Pharmacology University College London Gower Street London WC1E 6BT UK
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Miller RE, Belmadani A, Ishihara S, Tran PB, Ren D, Miller RJ, Malfait AM. Damage-associated molecular patterns generated in osteoarthritis directly excite murine nociceptive neurons through Toll-like receptor 4. Arthritis Rheumatol 2016; 67:2933-43. [PMID: 26245312 DOI: 10.1002/art.39291] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 07/16/2015] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To determine whether selected damage-associated molecular patterns (DAMPs) present in the osteoarthritic (OA) joints of mice excite nociceptors through Toll-like receptor 4 (TLR-4). METHODS The ability of S100A8 and α2 -macroglobulin to excite nociceptors was determined by measuring the release of monocyte chemoattractant protein 1 (MCP-1) by cultured dorsal root ganglion (DRG) cells as well as by measuring the intracellular calcium concentration ([Ca(2+) ]i ) in cultured DRG neurons from naive mice or from mice that had undergone surgical destabilization of the medial meniscus (DMM) 8 weeks previously. The role of TLR-4 was assessed using TLR-4(-/-) cells or a TLR-4 inhibitor. The [Ca(2+) ]i in neurons within ex vivo intact DRGs was measured in samples from Pirt-GCaMP3 mice. Neuronal expression of the Tlr4 gene was determined by in situ hybridization. DMM surgery was performed in wild-type and TLR-4(-/-) mice; mechanical allodynia was monitored, and joint damage was assessed histologically after 16 weeks. RESULTS DRG neurons from both naive and DMM mice expressed Tlr4. Both S100A8 and α2 -macroglobulin stimulated release of the proalgesic chemokine MCP-1 in DRG cultures, and the neurons rapidly responded to S100A8 and α2 -macroglobulin with increased [Ca(2+) ]i . Blocking TLR-4 inhibited these effects. Neurons within intact DRGs responded to the TLR-4 agonist lipopolysaccharide. In both of the calcium-imaging assays, it was primarily the nociceptor population of neurons that responded to TLR-4 ligands. TLR-4(-/-) mice were not protected from mechanical allodynia or from joint damage associated with DMM. CONCLUSION Our experiments suggest a role of TLR-4 signaling in the excitation of nociceptors by selected DAMPs. Further research is needed to delineate the importance of this pathway in relation to OA pain.
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Emerging Role of Spinal Cord TRPV1 in Pain Exacerbation. Neural Plast 2016; 2016:5954890. [PMID: 26885404 PMCID: PMC4738952 DOI: 10.1155/2016/5954890] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 07/20/2015] [Accepted: 08/12/2015] [Indexed: 12/25/2022] Open
Abstract
TRPV1 is well known as a sensor ion channel that transduces a potentially harmful environment into electrical depolarization of the peripheral terminal of the nociceptive primary afferents. Although TRPV1 is also expressed in central regions of the nervous system, its roles in the area remain unclear. A series of recent reports on the spinal cord synapses have provided evidence that TRPV1 plays an important role in synaptic transmission in the pain pathway. Particularly, in pathologic pain states, TRPV1 in the central terminal of sensory neurons and interneurons is suggested to commonly contribute to pain exacerbation. These observations may lead to insights regarding novel synaptic mechanisms revealing veiled roles of spinal cord TRPV1 and may offer another opportunity to modulate pathological pain by controlling TRPV1. In this review, we introduce historical perspectives of this view and details of the recent promising results. We also focus on extended issues and unsolved problems to fully understand the role of TRPV1 in pathological pain. Together with recent findings, further efforts for fine analysis of TRPV1's plastic roles in pain synapses at different levels in the central nervous system will promote a better understanding of pathologic pain mechanisms and assist in developing novel analgesic strategies.
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Nagy-Grócz G, Tar L, Bohár Z, Fejes-Szabó A, Laborc KF, Spekker E, Vécsei L, Párdutz Á. The modulatory effect of anandamide on nitroglycerin-induced sensitization in the trigeminal system of the rat. Cephalalgia 2015; 36:849-61. [PMID: 26512068 DOI: 10.1177/0333102415613766] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 09/18/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND One of the human and animal models of migraine is the systemic administration of the nitric oxide donor (NO) nitroglycerin (NTG). NO can provoke migraine-like attacks in migraineurs and initiates a self-amplifying process in the trigeminal system, probably leading to central sensitization. Recent studies suggest that the endocannabinoid system is involved in nociceptive signal processing and cannabinoid receptor (CB) agonists are able to attenuate nociception in animal models of pain. AIM The purpose of the present study was to investigate the modulatory effects of a CB agonist anandamide (AEA) on the NTG-induced expression of transient receptor potential vanilloid type 1 (TRPV1), neuronal nitric oxide synthase (nNOS), nuclear factor kappa B (NF-κB), cyclooxygenase-2 (COX-2) and kynurenine aminotransferase-II (KAT-II) in the upper cervical spinal cord (C1-C2) of the rat, where most of the trigeminal nociceptive afferents convey. METHODS A half hour before and one hour after NTG (10 mg/kg) or placebo injection, adult male Sprague-Dawley rats (n = 44) were treated with AEA (2 × 5 mg/kg). Four hours after placebo/NTG injection, the animals were perfused and the cervical spinal cords were removed for immunohistochemistry and Western blotting. RESULTS AND CONCLUSION Our results show that NTG is able to increase TRPV1, nNOS, NF-κB and COX-2 and decrease KAT-II expression in the C1-C2 segments. On the other hand, we have found that AEA modulates the NTG-induced changes, thus it influences the activation and central sensitization process in the trigeminal system, probably via CBs.
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Affiliation(s)
- Gábor Nagy-Grócz
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
| | - Lilla Tar
- Department of Neurology, University of Ulm, Germany
| | - Zsuzsanna Bohár
- MTA-SZTE Neuroscience Research Group, University of Szeged, Hungary
| | - Annamária Fejes-Szabó
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
| | - Klaudia Flóra Laborc
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
| | - Eleonóra Spekker
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
| | - László Vécsei
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary MTA-SZTE Neuroscience Research Group, University of Szeged, Hungary
| | - Árpád Párdutz
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Hungary
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213
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Silva M, Martins D, Tavares I, Morgado C. Inhibition of spinal 5-HT3R reverted diabetes-induced mechanical hypersensitivity in a GABAAR-mediated neurotransmission-dependent manner. Neuroscience 2015. [PMID: 26210577 DOI: 10.1016/j.neuroscience.2015.07.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Spinal 5-HT3 receptor (5-HT3R) has been implicated in chronic pain development. The extent to which 5-HT3R contributes to spinal sensitization and diabetic neuropathic pain (DNP) remains elusive and the mechanisms subserving the effects of 5-HT3R activation on spinal pain processing during chronic pain are still unclear. In this study, we evaluated the contribution of spinal 5-HT3R to pain facilitation and spinal sensitization during DNP, exploiting the role of GABAAR-mediated neurotransmission and glial activation in the effects elicited by intrathecal administration of a 5-HT3R antagonist. Mechanical nociception was evaluated by paw pressure test in streptozotocin (STZ)-diabetic and control rats after intrathecal (i.t.) administration of a 5-HT3R antagonist (Y25130). The spinal activation of extracellular signal-regulated kinases (ERKs) pathway and the expression of 5-HT3R, glial fibrillary acidic protein (GFAP; marker of astroglia activation) and ionized calcium binding adaptor molecule 1 (IBA-1; marker of microglia activation) were evaluated at the peak maximum effect of Y25130. The involvement of GABAAR-mediated neurotransmission in the behavioral pain effect of Y25130, was assessed in STZ-diabetic animals receiving i.t. administrations of muscimol (GABAAR agonist). Intrathecal administration of Y25130 reverted mechanical hyperalgesia and decreased the activation of ERKs in STZ-diabetic rats, while no effects were observed in control animals. The spinal activation of GABAAR by i.t. administration of muscimol abolished Y25130-driven antinociception. The expression of IBA-1, GFAP and 5-HT3R was unaltered by treatment. These findings point to a GABA-mediated pronociceptive role of spinal 5-HT3R during DNP.
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Affiliation(s)
- M Silva
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; i3S - Instituto de Inovação e investigação em Saúde, Universidade do Porto, Portugal
| | - D Martins
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; i3S - Instituto de Inovação e investigação em Saúde, Universidade do Porto, Portugal
| | - I Tavares
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; i3S - Instituto de Inovação e investigação em Saúde, Universidade do Porto, Portugal.
| | - C Morgado
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; i3S - Instituto de Inovação e investigação em Saúde, Universidade do Porto, Portugal
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214
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Breadth of tuning in taste afferent neurons varies with stimulus strength. Nat Commun 2015; 6:8171. [PMID: 26373451 PMCID: PMC4573454 DOI: 10.1038/ncomms9171] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/27/2015] [Indexed: 12/20/2022] Open
Abstract
Gustatory stimuli are detected by taste buds and transmitted to the hindbrain via sensory afferent neurons. Whether each taste quality (sweet, bitter and so on) is encoded by separate neurons (‘labelled lines') remains controversial. We used mice expressing GCaMP3 in geniculate ganglion sensory neurons to investigate taste-evoked activity. Using confocal calcium imaging, we recorded responses to oral stimulation with prototypic taste stimuli. Up to 69% of neurons respond to multiple tastants. Moreover, neurons tuned to a single taste quality at low concentration become more broadly tuned when stimuli are presented at higher concentration. Responses to sucrose and monosodium glutamate are most related. Although mice prefer dilute NaCl solutions and avoid concentrated NaCl, we found no evidence for two separate populations of sensory neurons that encode this distinction. Altogether, our data suggest that taste is encoded by activity in patterns of peripheral sensory neurons and challenge the notion of strict labelled line coding. How taste information is encoded and transmitted from the periphery to the cortex is not well understood. Here the authors provide evidence for population-based coding of taste by demonstrating that more than half of individual geniculate ganglion neurons are broadly tuned to basic taste stimuli.
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215
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Hao Y, Liu TT, He ZG, Wu W, Xiang HB. Hypothesis: CeM-PAG GABAergic circuits may be implicated in sudden unexpected death in epilepsy by melanocortinergic signaling. Epilepsy Behav 2015; 50:25-8. [PMID: 26101104 DOI: 10.1016/j.yebeh.2015.04.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 04/29/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Yan Hao
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, People's Republic of China
| | - Tao-Tao Liu
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, People's Republic of China
| | - Zhi-Gang He
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, People's Republic of China
| | - Wei Wu
- Department of Orthopaedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, Hubei, People's Republic of China.
| | - Hong-Bing Xiang
- Department of Anesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, People's Republic of China.
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216
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Luo J, Feng J, Liu S, Walters ET, Hu H. Molecular and cellular mechanisms that initiate pain and itch. Cell Mol Life Sci 2015; 72:3201-23. [PMID: 25894692 PMCID: PMC4534341 DOI: 10.1007/s00018-015-1904-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/20/2015] [Accepted: 04/07/2015] [Indexed: 12/17/2022]
Abstract
Somatosensory neurons mediate our sense of touch. They are critically involved in transducing pain and itch sensations under physiological and pathological conditions, along with other skin-resident cells. Tissue damage and inflammation can produce a localized or systemic sensitization of our senses of pain and itch, which can facilitate our detection of threats in the environment. Although acute pain and itch protect us from further damage, persistent pain and itch are debilitating. Recent exciting discoveries have significantly advanced our knowledge of the roles of membrane-bound G protein-coupled receptors and ion channels in the encoding of information leading to pain and itch sensations. This review focuses on molecular and cellular events that are important in early stages of the biological processing that culminates in our senses of pain and itch.
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Affiliation(s)
- Jialie Luo
- Department of Anesthesiology, The Center for the Study of Itch, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA
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217
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Zhang Y, Zhao S, Rodriguez E, Takatoh J, Han BX, Zhou X, Wang F. Identifying local and descending inputs for primary sensory neurons. J Clin Invest 2015; 125:3782-94. [PMID: 26426077 DOI: 10.1172/jci81156] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 07/23/2015] [Indexed: 12/25/2022] Open
Abstract
Primary pain and touch sensory neurons not only detect internal and external sensory stimuli, but also receive inputs from other neurons. However, the neuronal derived inputs for primary neurons have not been systematically identified. Using a monosynaptic rabies viruses-based transneuronal tracing method combined with sensory-specific Cre-drivers, we found that sensory neurons receive intraganglion, intraspinal, and supraspinal inputs, the latter of which are mainly derived from the rostroventral medulla (RVM). The viral-traced central neurons were largely inhibitory but also consisted of some glutamatergic neurons in the spinal cord and serotonergic neurons in the RVM. The majority of RVM-derived descending inputs were dual GABAergic and enkephalinergic (opioidergic). These inputs projected through the dorsolateral funiculus and primarily innervated layers I, II, and V of the dorsal horn, where pain-sensory afferents terminate. Silencing or activation of the dual GABA/enkephalinergic RVM neurons in adult animals substantially increased or decreased behavioral sensitivity, respectively, to heat and mechanical stimuli. These results are consistent with the fact that both GABA and enkephalin can exert presynaptic inhibition of the sensory afferents. Taken together, this work provides a systematic view of and a set of tools for examining peri- and extrasynaptic regulations of pain-afferent transmission.
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218
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Huang WX, Yu F, Sanchez RM, Liu YQ, Min JW, Hu JJ, Bsoul NB, Han S, Yin J, Liu WH, He XH, Peng BW. TRPV1 promotes repetitive febrile seizures by pro-inflammatory cytokines in immature brain. Brain Behav Immun 2015; 48:68-77. [PMID: 25801060 DOI: 10.1016/j.bbi.2015.01.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/22/2015] [Accepted: 01/26/2015] [Indexed: 10/23/2022] Open
Abstract
Febrile seizure (FS) is the most common seizure disorder in children, and children with FS are regarded as a high risk for the eventual development of epilepsy. Brain inflammation may be implicated in the mechanism of FS. Transient receptor potential vanilloid 1 (TRPV1) is believed to act as a monitor and regulator of body temperature. The role of inflammation in synaptic plasticity mediation indicates that TRPV1 is relevant to several nervous system diseases, such as epilepsy. Here, we report a critical role for TRPV1 in a febrile seizure mouse model and reveal increased levels of pro-inflammatory factors in the immature brain. Animals were subjected to hyperthermia for 30 min, which generates seizures lasting approximately 20 min, and then were used for experiments. To invoke frequently repetitive febrile seizures, mice are exposed to hyperthermia for three times daily at an interval of 4h between every time induced seizure, and a total of 4 days to induce. Behavioral testing for febrile seizures revealed that a TRPV1 knock-out mouse model demonstrated a prolonged onset latency and a shortened duration and seizure grade of febrile seizure when compared with wild type (WT) mice. The expression levels of both TRPV1 mRNA and protein increased after a hyperthermia-induced febrile seizure in WT mice. Notably, TRPV1 activation resulted in a significant elevation in the expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and HMGB1) in the hippocampus and cortex. These data indicate that the reduction of TRPV1 expression parallels a decreased susceptibility to febrile seizures. Thus, preventative strategies might be developed for use during febrile seizures.
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Affiliation(s)
- Wen-Xian Huang
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Fang Yu
- Department of Pathology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China
| | - Russell M Sanchez
- Dept of Surgery, College of Medicine, Texas A&M Health Science Center, Neuroscience Institute, Scott & White Hospital, & Central Texas Veterans Health Care System, Temple, TX, United States
| | - Yu-Qiang Liu
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Jia-Wei Min
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Jiang-Jian Hu
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Najeeb Bassam Bsoul
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Song Han
- Department of Pathophysiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Jun Yin
- Department of Pathophysiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Wan-Hong Liu
- Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China
| | - Xiao-Hua He
- Department of Pathophysiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China.
| | - Bi-Wen Peng
- Department of Physiology, Hubei Provincial Key Laboratory of Developmentally Originated Disorder, School of Basic Medical Sciences, Wuhan University, Wuhan 430071, China.
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219
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Lin JJ, Du Y, Cai WK, Kuang R, Chang T, Zhang Z, Yang YX, Sun C, Li ZY, Kuang F. Toll-like receptor 4 signaling in neurons of trigeminal ganglion contributes to nociception induced by acute pulpitis in rats. Sci Rep 2015. [PMID: 26224622 PMCID: PMC4519790 DOI: 10.1038/srep12549] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Pain caused by acute pulpitis (AP) is a common symptom in clinical settings. However, its underlying mechanisms have largely remained unknown. Using AP model, we demonstrated that dental injury caused severe pulp inflammation with up-regulated serum IL-1β. Assessment from head-withdrawal reflex thresholds (HWTs) and open-field test demonstrated nociceptive response at 1 day post injury. A consistent up-regulation of Toll-like receptor 4 (TLR4) in the trigeminal ganglion (TG) ipsilateral to the injured pulp was found; and downstream signaling components of TLR4, including MyD88, TRIF and NF-κB, and cytokines such as TNF-α and IL-1β, were also increased. Retrograde labeling indicated that most TLR4 positve neuron in the TG innnervated the pulp and TLR4 immunoreactivity was mainly in the medium and small neurons. Double labeling showed that the TLR4 expressing neurons in the ipsilateral TG were TRPV1 and CGRP positive, but IB4 negative. Furthermore, blocking TLR4 by eritoran (TLR4 antagonist) in TGs of the AP model significantly down-regulated MyD88, TRIF, NF-κB, TNF-α and IL-1β production and behavior of nociceptive response. Our findings suggest that TLR4 signaling in TG cells, particularly the peptidergic TRPV1 neurons, plays a key role in AP-induced nociception, and indicate that TLR4 signaling could be a potential therapeutic target for orofacial pain.
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Affiliation(s)
- Jia-Ji Lin
- 1] Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China [2] Department of Neurobiology and Collaborative Innovation Center for Brain Science, School of Basic Medicine, The Fourth Military Medical University, Xi'an, 710032, China
| | - Yi Du
- 1] State Key Laboratory of Military Stomatology, Department of Operative Dentistry and Endodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032,China [2] Department of Endodontics, Jinan Stomatological Hospital, Jinan, 250001, China
| | - Wen-Ke Cai
- 1] Department of Cardio-Thoracic Surgery, Kunming General Hospital of Chengdu Military Region, Kunming, 650000, China [2] Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Rong Kuang
- State Key Laboratory of Military Stomatology, Department of Operative Dentistry and Endodontics, School of Stomatology, The Fourth Military Medical University, Xi'an, 710032,China
| | - Ting Chang
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Zhuo Zhang
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Yong-Xiang Yang
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Chao Sun
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Zhu-Yi Li
- Department of Neurology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, 710004, China
| | - Fang Kuang
- Department of Neurobiology and Collaborative Innovation Center for Brain Science, School of Basic Medicine, The Fourth Military Medical University, Xi'an, 710032, China
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220
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Redefining the concept of protease-activated receptors: cathepsin S evokes itch via activation of Mrgprs. Nat Commun 2015. [PMID: 26216096 PMCID: PMC4520244 DOI: 10.1038/ncomms8864] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Sensory neurons expressing Mas-related G protein coupled receptors (Mrgprs) mediate histamine-independent itch. We show that the cysteine protease cathepsin S activates MrgprC11 and evokes receptor-dependent scratching in mice. In contrast to its activation of conventional protease-activated receptors, cathepsin S mediated activation of MrgprC11 did not involve the generation of a tethered ligand. We demonstrate further that different cysteine proteases selectively activate specific mouse and human Mrgpr family members. This expansion of our understanding by which proteases interact with GPCRs redefines the concept of what constitutes a protease-activated receptor. The findings also implicate proteases as ligands to members of this orphan receptor family while providing new insights into how cysteine proteases contribute to itch.
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221
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Zakharov A, Vitale C, Kilinc E, Koroleva K, Fayuk D, Shelukhina I, Naumenko N, Skorinkin A, Khazipov R, Giniatullin R. Hunting for origins of migraine pain: cluster analysis of spontaneous and capsaicin-induced firing in meningeal trigeminal nerve fibers. Front Cell Neurosci 2015; 9:287. [PMID: 26283923 PMCID: PMC4516892 DOI: 10.3389/fncel.2015.00287] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Accepted: 07/13/2015] [Indexed: 12/19/2022] Open
Abstract
Trigeminal nerves in meninges are implicated in generation of nociceptive firing underlying migraine pain. However, the neurochemical mechanisms of nociceptive firing in meningeal trigeminal nerves are little understood. In this study, using suction electrode recordings from peripheral branches of the trigeminal nerve in isolated rat meninges, we analyzed spontaneous and capsaicin-induced orthodromic spiking activity. In control, biphasic single spikes with variable amplitude and shapes were observed. Application of the transient receptor potential vanilloid 1 (TRPV1) agonist capsaicin to meninges dramatically increased firing whereas the amplitudes and shapes of spikes remained essentially unchanged. This effect was antagonized by the specific TRPV1 antagonist capsazepine. Using the clustering approach, several groups of uniform spikes (clusters) were identified. The clustering approach combined with capsaicin application allowed us to detect and to distinguish "responder" (65%) from "non-responder" clusters (35%). Notably, responders fired spikes at frequencies exceeding 10 Hz, high enough to provide postsynaptic temporal summation of excitation at brainstem and spinal cord level. Almost all spikes were suppressed by tetrodotoxin (TTX) suggesting an involvement of the TTX-sensitive sodium channels in nociceptive signaling at the peripheral branches of trigeminal neurons. Our analysis also identified transient (desensitizing) and long-lasting (slowly desensitizing) responses to the continuous application of capsaicin. Thus, the persistent activation of nociceptors in capsaicin-sensitive nerve fibers shown here may be involved in trigeminal pain signaling and plasticity along with the release of migraine-related neuropeptides from TRPV1 positive neurons. Furthermore, cluster analysis could be widely used to characterize the temporal and neurochemical profiles of other pain transducers likely implicated in migraine.
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Affiliation(s)
- A. Zakharov
- Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
- Department of Physiology, Kazan State Medical UniversityKazan, Russia
| | - C. Vitale
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - E. Kilinc
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
- Medical Faculty, Department of Physiology, Abant Izzet Baysal UniversityBolu, Turkey
| | - K. Koroleva
- Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - D. Fayuk
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - I. Shelukhina
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RASMoscow, Russia
| | - N. Naumenko
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
| | - A. Skorinkin
- Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
- Kazan Institute of Biochemistry and BiophysicsKazan, Russia
| | - R. Khazipov
- Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
- INSERM U901/Aix Marseille UniversityMarseille, France
| | - R. Giniatullin
- Laboratory of Neurobiology, Kazan Federal UniversityKazan, Russia
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern FinlandKuopio, Finland
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222
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Spinal dopaminergic projections control the transition to pathological pain plasticity via a D1/D5-mediated mechanism. J Neurosci 2015; 35:6307-17. [PMID: 25904784 DOI: 10.1523/jneurosci.3481-14.2015] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The mechanisms that lead to the maintenance of chronic pain states are poorly understood, but their elucidation could lead to new insights into how pain becomes chronic and how it can potentially be reversed. We investigated the role of spinal dorsal horn neurons and descending circuitry in plasticity mediating a transition to pathological pain plasticity suggesting the presence of a chronic pain state using hyperalgesic priming. We found that when dorsal horn neurokinin 1 receptor-positive neurons or descending serotonergic neurons were ablated before hyperalgesic priming, IL-6- and carrageenan-induced mechanical hypersensitivity was impaired, and subsequent prostaglandin E2 (PGE2) response was blunted. However, when these neurons were lesioned after the induction of priming, they had no effect on the PGE2 response, reflecting differential mechanisms driving plasticity in a primed state. In stark contrast, animals with a spinally applied dopaminergic lesion showed intact IL-6- and carrageenan-induced mechanical hypersensitivity, but the subsequent PGE2 injection failed to cause mechanical hypersensitivity. Moreover, ablating spinally projecting dopaminergic neurons after the resolution of the IL-6- or carrageenan-induced response also reversed the maintenance of priming as assessed through mechanical hypersensitivity and the mouse grimace scale. Pharmacological antagonism of spinal dopamine D1/D5 receptors reversed priming, whereas D1/D5 agonists induced mechanical hypersensitivity exclusively in primed mice. Strikingly, engagement of D1/D5 coupled with anisomycin in primed animals reversed a chronic pain state, consistent with reconsolidation-like effects in the spinal dorsal horn. These findings demonstrate a novel role for descending dopaminergic neurons in the maintenance of pathological pain plasticity.
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223
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Kirkpatrick DR, McEntire DM, Hambsch ZJ, Kerfeld MJ, Smith TA, Reisbig MD, Youngblood CF, Agrawal DK. Therapeutic Basis of Clinical Pain Modulation. Clin Transl Sci 2015; 8:848-56. [PMID: 25962969 DOI: 10.1111/cts.12282] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Pain is a hallmark of almost all bodily ailments and can be modulated by agents, including analgesics and anesthetics that suppress pain signals in the central nervous system. Defects in the modulatory systems, including the endogenous pain-inhibitory pathways, are a major factor in the initiation and chronicity of pain. Thus, pain modulation is particularly applicable to the practice of medicine. This review summarizes the existing literature on pain modulation. Here, we critically reviewed the literature from PubMed on pain modulation published primarily within the past 5 years in high impact journals. Specifically, we have discussed important anatomical landmarks of pain modulation and outlined the endogenous networks and underlying mechanisms of clinically relevant pain modulatory methods. The Gate Control Theory is briefly presented with discussion on the capacity of pain modulation to cause both hyper- and hypoalgesia. An emphasis has been given to highlight key areas in pain research that, because of unanswered questions or therapeutic potential, merit additional scientific scrutiny. The information presented in this paper would be helpful in developing novel therapies, metrics, and interventions for improved patient management.
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Affiliation(s)
- Daniel R Kirkpatrick
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Dan M McEntire
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Zakary J Hambsch
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Mitchell J Kerfeld
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Tyler A Smith
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Mark D Reisbig
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Charles F Youngblood
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
| | - Devendra K Agrawal
- Center for Clinical & Translational Science and Department of Anesthesiology, Creighton University School of Medicine, Omaha, Nebraska, USA
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224
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Okamoto K, Katagiri A, Rahman M, Thompson R, Bereiter DA. Inhibition of temporomandibular joint input to medullary dorsal horn neurons by 5HT3 receptor antagonist in female rats. Neuroscience 2015; 299:35-44. [PMID: 25913635 DOI: 10.1016/j.neuroscience.2015.04.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/17/2015] [Accepted: 04/16/2015] [Indexed: 12/19/2022]
Abstract
Repeated forced swim (FS) conditioning enhances nociceptive responses to temporomandibular joint (TMJ) stimulation in female rats. The basis for FS-induced TMJ hyperalgesia remains unclear. To test the hypothesis that serotonin 3 receptor (5HT3R) mechanisms contribute to enhanced TMJ nociception after FS, ovariectomized female rats were treated with estradiol and subjected to FS for three days. On day 4, rats were anesthetized with isoflurane and TMJ-responsive neurons were recorded from superficial and deep laminae at the trigeminal subnucleus caudalis/upper cervical (Vc/C1-2) region and electromyographic (EMG) activity was recorded from the masseter muscle. Only Vc/C1-2 neurons activated by intra-TMJ injections of ATP were included for further analysis. Although neurons in both superficial and deep laminae were activated by ATP, only neurons in deep laminae displayed enhanced responses after FS. Local application of the 5HT3R antagonist, ondansetron (OND), at the Vc/C1-2 region reduced the ATP-evoked responses of neurons in superficial and deep laminae and reduced the EMG response in both sham and FS rats. OND also decreased the spontaneous firing rate of neurons in deep laminae and reduced the high-threshold convergent cutaneous receptive field area of neurons in superficial and deep laminae in both sham and FS rats. These results revealed that central application of a 5HT3R antagonist, had widespread effects on the properties of TMJ-responsive neurons at the Vc/C1-2 region and on jaw muscle reflexes under sham and FS conditions. It is concluded that 5HT3R does not play a unique role in mediating stress-induced hyperalgesia related to TMJ nociception.
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Affiliation(s)
- K Okamoto
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States.
| | - A Katagiri
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - M Rahman
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - R Thompson
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
| | - D A Bereiter
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN 55455, United States
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225
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Zeidler C, Lüling H, Dieckhöfer A, Osada N, Schedel F, Steinke S, Augustin M, Ständer S. Capsaicin 8% cutaneous patch: a promising treatment for brachioradial pruritus? Br J Dermatol 2015; 172:1669-1671. [PMID: 25354282 DOI: 10.1111/bjd.13501] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C Zeidler
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
| | - H Lüling
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
| | - A Dieckhöfer
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
| | - N Osada
- Institute for Medical Informatics, University Hospital of Münster, Münster, Germany
| | - F Schedel
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
| | - S Steinke
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
| | - M Augustin
- Institute and German Center for Health Services Research in Dermatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - S Ständer
- Department of Dermatology, Competence Center Chronic Pruritus, University Hospital of Münster, Münster, Germany
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226
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Mika J, Jurga AM, Starnowska J, Wasylewski M, Rojewska E, Makuch W, Kwiatkowski K, Malek N, Przewlocka B. Effects of chronic doxepin and amitriptyline administration in naïve mice and in neuropathic pain mice model. Neuroscience 2015; 294:38-50. [PMID: 25769941 DOI: 10.1016/j.neuroscience.2015.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 02/02/2023]
Abstract
Neuropathic pain is a severe clinical problem, often appearing as a co-symptom of many diseases or manifesting as a result of damage to the nervous system. Many drugs and agents are currently used for the treatment of neuropathic pain, such as tricyclic antidepressants (TCAs). The aims of this paper were to test the effects of two classic TCAs, doxepin and amitriptyline, in naïve animals and in a model of neuropathic pain and to determine the role of cytokine activation in the effects of these drugs. All experiments were carried out with Albino-Swiss mice using behavioral tests (von Frey test and the cold plate test) and biochemical analyses (qRT-PCR and Western blot). In the mice subjected to chronic constriction injury (CCI), doxepin and amitriptyline attenuated the symptoms of neuropathic pain and diminished the CCI-induced increase in the levels of spinal interleukin (IL)-6 and -1β mRNA, but not the protein levels of these cytokines, measured on day 12. Unexpectedly, chronic administration of doxepin or amitriptyline for 12 days produced allodynia and hyperalgesia in naïve mice. The treatment with these drugs did not influence the spinal levels of IL-1β and IL-6 mRNA, however, the protein levels of these pronociceptive factors were increased. The administration of ondansetron (5-HT3 receptor antagonist) significantly weakened the allodynia and hyperalgesia induced by both antidepressants in naïve mice; in contrast, yohimbine (α2-adrenergic receptors antagonist) did not influence these effects. Allodynia and hyperalgesia induced in naïve animals by amitriptyline and doxepin may be associated with an increase in the levels of pronociceptive cytokines resulting from 5-HT3-induced hypersensitivity. Our results provide new and important information about the possible side effects of antidepressants. Further investigation of these mechanisms may help to guide decisions about the use of classic TCAs for therapy.
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Affiliation(s)
- J Mika
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland.
| | - A M Jurga
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - J Starnowska
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - M Wasylewski
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - E Rojewska
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - W Makuch
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - K Kwiatkowski
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - N Malek
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland
| | - B Przewlocka
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, Krakow, Poland.
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227
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The influence of microglia activation on the efficacy of amitriptyline, doxepin, milnacipran, venlafaxine and fluoxetine in a rat model of neuropathic pain. Eur J Pharmacol 2015; 749:115-23. [DOI: 10.1016/j.ejphar.2014.11.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 11/12/2014] [Accepted: 11/17/2014] [Indexed: 01/18/2023]
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228
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Dussor G, Yan J, Xie JY, Ossipov MH, Dodick DW, Porreca F. Targeting TRP channels for novel migraine therapeutics. ACS Chem Neurosci 2014; 5:1085-96. [PMID: 25138211 PMCID: PMC4240253 DOI: 10.1021/cn500083e] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
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Migraine is increasingly understood
to be a disorder of the brain.
In susceptible individuals, a variety of “triggers”
may influence altered central excitability, resulting in the activation
and sensitization of trigeminal nociceptive afferents surrounding
blood vessels (i.e., the trigeminovascular system), leading to migraine
pain. Transient receptor potential (TRP) channels are expressed in
a subset of dural afferents, including those containing calcitonin
gene related peptide (CGRP). Activation of TRP channels promotes excitation
of nociceptive afferent fibers and potentially lead to pain. In addition
to pain, allodynia to mechanical and cold stimuli can result from
sensitization of both peripheral afferents and of central pain pathways.
TRP channels respond to a variety of endogenous conditions including
chemical mediators and low pH. These channels can be activated by
exogenous stimuli including a wide range of chemical and environmental
irritants, some of which have been demonstrated to trigger migraine
in humans. Activation of TRP channels can elicit CGRP release, and
blocking the effects of CGRP through receptor antagonism or antibody
strategies has been demonstrated to be effective in the treatment
of migraine. Identification of approaches that can prevent activation
of TRP channels provides an additional novel strategy for discovery
of migraine therapeutics.
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Affiliation(s)
- Gregory Dussor
- School
of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, Texas 75080, United States
| | - J. Yan
- Department
of Pharmacology, University of Washington, Seattle, Washington 98195, United States
| | - Jennifer Y. Xie
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
| | - Michael H. Ossipov
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
| | - David W. Dodick
- Department
of Neurology, Mayo Clinic Arizona, Phoenix, Arizona 85054, United States
| | - Frank Porreca
- Department
of Pharmacology, University of Arizona College of Medicine, Tucson, Arizona 85724, United States
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229
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Cai YQ, Wang W, Hou YY, Pan ZZ. Optogenetic activation of brainstem serotonergic neurons induces persistent pain sensitization. Mol Pain 2014; 10:70. [PMID: 25410898 PMCID: PMC4247651 DOI: 10.1186/1744-8069-10-70] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 06/18/2014] [Indexed: 02/07/2023] Open
Abstract
Background The rostral ventromedial medulla (RVM) is a key brainstem structure that conveys powerful descending influence of the central pain-modulating system on spinal pain transmission and processing. Serotonergic (5-HT) neurons are a major component in the heterogeneous populations of RVM neurons and in the descending pathways from RVM. However, the descending influence of RVM 5-HT neurons on pain behaviors remains unclear. Results In this study using optogenetic stimulation in tryptophan hydroxylase 2 (TPH2)- Channelrhodopsin 2 (ChR2) transgenic mice, we determined the behavioral effects of selective activation of RVM 5-HT neurons on mechanical and thermal pain behaviors in vivo. We found that ChR2-EYFP-positive neurons strongly co-localized with TPH2-positive (5-HT) neurons in RVM. Optogenetic stimulation significantly increased c-fos expression in 5-HT cells in the RVM of TPH2-ChR2 mice, but not in wild type mice. Behaviorally, the optogenetic stimulation decreased both mechanical and thermal pain threshold in an intensity-dependent manner, with repeated stimulation producing sensitized pain behavior for up to two weeks. Conclusions These results suggest that selective activation of RVM 5-HT neurons exerts a predominant effect of pain facilitation under control conditions.
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Affiliation(s)
| | | | | | - Zhizhong Z Pan
- Department of Anesthesiology and Pain Medicine, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA.
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230
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Hegarty DM, Hermes SM, Largent-Milnes TM, Aicher SA. Capsaicin-responsive corneal afferents do not contain TRPV1 at their central terminals in trigeminal nucleus caudalis in rats. J Chem Neuroanat 2014; 61-62:1-12. [PMID: 24996127 DOI: 10.1016/j.jchemneu.2014.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 06/23/2014] [Accepted: 06/23/2014] [Indexed: 10/25/2022]
Abstract
We examined the substrates for ocular nociception in adult male Sprague-Dawley rats. Capsaicin application to the ocular surface in awake rats evoked nocifensive responses and suppressed spontaneous grooming responses. Thus, peripheral capsaicin was able to activate the central pathways encoding ocular nociception. Our capsaicin stimulus evoked c-Fos expression in a select population of neurons within rostral trigeminal nucleus caudalis in anesthetized rats. These activated neurons also received direct contacts from corneal afferent fibers traced with cholera toxin B from the corneal surface. However, the central terminals of the corneal afferents that contacted capsaicin-activated trigeminal neurons did not contain TRPV1. To determine if TRPV1 expression had been altered by capsaicin stimulation, we examined TRPV1 content of corneal afferents in animals that did not receive capsaicin stimulation. These studies confirmed that while TRPV1 was present in 30% of CTb-labeled corneal afferent neurons within the trigeminal ganglion, TRPV1 was only detected in 2% of the central terminals of these corneal afferents within the trigeminal nucleus caudalis. Other TRP channels were also present in low proportions of central corneal afferent terminals in unstimulated animals (TRPM8, 2%; TRPA1, 10%). These findings indicate that a pathway from the cornea to rostral trigeminal nucleus caudalis is involved in corneal nociceptive transmission, but that central TRP channel expression is unrelated to the type of stimulus transduced by the peripheral nociceptive endings.
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Affiliation(s)
- Deborah M Hegarty
- Department of Physiology and Pharmacology, Oregon Health & Science University, Mail code: L334, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, United States.
| | - Sam M Hermes
- Department of Physiology and Pharmacology, Oregon Health & Science University, Mail code: L334, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, United States.
| | - Tally M Largent-Milnes
- Department of Physiology and Pharmacology, Oregon Health & Science University, Mail code: L334, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, United States.
| | - Sue A Aicher
- Department of Physiology and Pharmacology, Oregon Health & Science University, Mail code: L334, 3181 Sam Jackson Park Road, Portland, OR 97239-3098, United States.
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231
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Nilius B, Szallasi A. Transient Receptor Potential Channels as Drug Targets: From the Science of Basic Research to the Art of Medicine. Pharmacol Rev 2014; 66:676-814. [DOI: 10.1124/pr.113.008268] [Citation(s) in RCA: 348] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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232
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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.
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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.
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233
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Martins D, Tavares I, Morgado C. "Hotheaded": the role OF TRPV1 in brain functions. Neuropharmacology 2014; 85:151-7. [PMID: 24887171 DOI: 10.1016/j.neuropharm.2014.05.034] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/12/2014] [Accepted: 05/20/2014] [Indexed: 12/24/2022]
Abstract
The TRPV1 (vanilloid 1) channel is best known for its role in sensory transmission in the nociceptive neurons of the peripheral nervous system. Although first studied in the dorsal root ganglia as the receptor for capsaicin, TRPV1 has been recently recognized to have a broader distribution in the central nervous system, where it is likely to constitute an atypical neurotransmission system involved in several functions through modulation of both neuronal and glial activities. The endovanilloid-activated brain TRPV1 channels seem to be involved in somatosensory, motor and visceral functions. Recent studies suggested that TRPV1 channels also account for more complex functions, as addiction, anxiety, mood and cognition/learning. However, more studies are needed before the relevance of TRPV1 in brain activity can be clearly stated. This review highlights the increasing importance of TRPV1 as a regulator of brain function and discusses possible bases for the future development of new therapeutic approaches that by targeting brain TRPV1 receptors might be used for the treatment of several neurological disorders.
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Affiliation(s)
- D Martins
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
| | - I Tavares
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal
| | - C Morgado
- Departamento de Biologia Experimental, Faculdade de Medicina, Universidade do Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal.
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234
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235
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Kim YS, Chu Y, Han L, Park K, Li M, Li Z, LaVinka P, Caterina MJ, Ren K, Dubner R, Wei F, Dong X. Imaging orofacial pain in mice. Mol Pain 2014. [PMCID: PMC4304368 DOI: 10.1186/1744-8069-10-s1-o2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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