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Hori A, Fukazawa A, Katanosaka K, Mizuno M, Hotta N. Mechanosensitive channels in the mechanical component of the exercise pressor reflex. Auton Neurosci 2023; 250:103128. [PMID: 37925831 DOI: 10.1016/j.autneu.2023.103128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 10/24/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023]
Abstract
The cardiovascular response is appropriately regulated during exercise to meet the metabolic demands of the active muscles. The exercise pressor reflex is a neural feedback mechanism through thin-fiber muscle afferents activated by mechanical and metabolic stimuli in the active skeletal muscles. The mechanical component of this reflex is referred to as skeletal muscle mechanoreflex. Its initial step requires mechanotransduction mediated by mechanosensors, which convert mechanical stimuli into biological signals. Recently, various mechanosensors have been identified, and their contributions to muscle mechanoreflex have been actively investigated. Nevertheless, the mechanosensitive channels responsible for this muscular reflex remain largely unknown. This review discusses progress in our understanding of muscle mechanoreflex under healthy conditions, focusing on mechanosensitive channels.
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Affiliation(s)
- Amane Hori
- College of Life and Health Sciences, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan; Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-8472, Japan; Department of Applied Clinical Research, UT Southwestern Medical Center, Dallas, TX 75390-9174, USA
| | - Ayumi Fukazawa
- Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-8472, Japan; Department of Applied Clinical Research, UT Southwestern Medical Center, Dallas, TX 75390-9174, USA
| | - Kimiaki Katanosaka
- College of Life and Health Sciences, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | - Masaki Mizuno
- Department of Applied Clinical Research, UT Southwestern Medical Center, Dallas, TX 75390-9174, USA
| | - Norio Hotta
- College of Life and Health Sciences, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
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2
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Cui JJ, Wang J, Xu DS, Wu S, Guo YT, Su YX, Liu YH, Wang YQ, Jing XH, Bai WZ. Alexa Fluor 488-conjugated cholera toxin subunit B optimally labels neurons 3-7 days after injection into the rat gastrocnemius muscle. Neural Regen Res 2022; 17:2316-2320. [PMID: 35259856 PMCID: PMC9083145 DOI: 10.4103/1673-5374.337055] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Neural tract tracing is used to study neural pathways and evaluate neuronal regeneration following nerve injuries. However, it is not always clear which tracer should be used to yield optimal results. In this study, we examined the use of Alexa Fluor 488-conjugated cholera toxin subunit B (AF488-CTB). This was injected into the gastrocnemius muscle of rats, and it was found that motor, sensory, and sympathetic neurons were labeled in the spinal ventral horn, dorsal root ganglia, and sympathetic chain, respectively. Similar results were obtained when we injected AF594-CTB into the tibialis anterior muscle. The morphology and number of neurons were evaluated at different time points following the AF488-CTB injection. It was found that labeled motor and sensory neurons could be observed 12 hours post-injection. The intensity was found to increase over time, and the morphology appeared clear and complete 3-7 days post-injection, with clearly distinguishable motor neuron axons and dendrites. However, 14 days after the injection, the quality of the images decreased and the neurons appeared blurred and incomplete. Nissl and immunohistochemical staining showed that the AF488-CTB-labeled neurons retained normal neurochemical and morphological features, and the surrounding microglia were also found to be unaltered. Overall, these results imply that the cholera toxin subunit B, whether unconjugated or conjugated with Alexa Fluor, is effective for retrograde tracing in muscular tissues and that it would also be suitable for evaluating the regeneration or degeneration of injured nerves.
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Affiliation(s)
- Jing-Jing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Dong-Sheng Xu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Shuang Wu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Ya-Ting Guo
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Xin Su
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yi-Han Liu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yu-Qing Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Xiang-Hong Jing
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wan-Zhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
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3
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Borghi SM, Bussulo SKD, Pinho-Ribeiro FA, Fattori V, Carvalho TT, Rasquel-Oliveira FS, Zaninelli TH, Ferraz CR, Casella AMB, Cunha FQ, Cunha TM, Casagrande R, Verri WA. Intense Acute Swimming Induces Delayed-Onset Muscle Soreness Dependent on Spinal Cord Neuroinflammation. Front Pharmacol 2022; 12:734091. [PMID: 35069187 PMCID: PMC8776654 DOI: 10.3389/fphar.2021.734091] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/25/2021] [Indexed: 12/27/2022] Open
Abstract
Unaccustomed exercise involving eccentric contractions, high intensity, or long duration are recognized to induce delayed-onset muscle soreness (DOMS). Myocyte damage and inflammation in affected peripheral tissues contribute to sensitize muscle nociceptors leading to muscle pain. However, despite the essential role of the spinal cord in the regulation of pain, spinal cord neuroinflammatory mechanisms in intense swimming-induced DOMS remain to be investigated. We hypothesized that spinal cord neuroinflammation contributes to DOMS. C57BL/6 mice swam for 2 h to induce DOMS, and nociceptive spinal cord mechanisms were evaluated. DOMS triggered the activation of astrocytes and microglia in the spinal cord 24 h after exercise compared to the sham group. DOMS and DOMS-induced spinal cord nuclear factor κB (NFκB) activation were reduced by intrathecal treatments with glial inhibitors (fluorocitrate, α-aminoadipate, and minocycline) and NFκB inhibitor [pyrrolidine dithiocarbamate (PDTC)]. Moreover, DOMS was also reduced by intrathecal treatments targeting C-X3-C motif chemokine ligand 1 (CX3CL1), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β or with recombinant IL-10. In agreement, DOMS induced the mRNA and protein expressions of CX3CR1, TNF-α, IL-1β, IL-10, c-Fos, and oxidative stress in the spinal cord. All these immune and cellular alterations triggered by DOMS were amenable by intrathecal treatments with glial and NFκB inhibitors. These results support a role for spinal cord glial cells, via NFκB, cytokines/chemokines, and oxidative stress, in DOMS. Thus, unveiling neuroinflammatory mechanisms by which unaccustomed exercise induces central sensitization and consequently DOMS.
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Affiliation(s)
- Sergio M Borghi
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil.,Centro de Pesquisa Em Ciências da Saúde, Universidade Norte do Paraná, Londrina, Brazil
| | - Sylvia K D Bussulo
- Centro de Pesquisa Em Ciências da Saúde, Universidade Norte do Paraná, Londrina, Brazil
| | - Felipe A Pinho-Ribeiro
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Victor Fattori
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Thacyana T Carvalho
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Fernanda S Rasquel-Oliveira
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Tiago H Zaninelli
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Camila R Ferraz
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
| | - Antônio M B Casella
- Departamento de Clínica Médica, Centro de Ciências da Saúde, Universidade Estadual de Londrina, Londrina, Brazil
| | - Fernando Q Cunha
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Thiago M Cunha
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Rubia Casagrande
- Departamento de Ciências Farmacêuticas, Centro de Ciências de Saúde, Hospital Universitário, Universidade Estadual de Londrina, Londrina, Brazil
| | - Waldiceu A Verri
- Departamento de Ciências Patológicas, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, Brazil
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4
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Li Y, Hari K, Lucas-Osma AM, Fenrich KK, Bennett DJ, Hammar I, Jankowska E. Branching points of primary afferent fibers are vital for the modulation of fiber excitability by epidural DC polarization and by GABA in the rat spinal cord. J Neurophysiol 2020; 124:49-62. [PMID: 32459560 DOI: 10.1152/jn.00161.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The aim of the study was to examine whether the sustained increases in the excitability of afferent fibers traversing the dorsal columns evoked by their polarization depend on the branching points of these fibers. To this end, the effects of epidural polarization were compared in four spinal regions in deeply anesthetized rats; two with the densest collateralization of muscle afferent fibers (above motor nuclei and Clarke's column) and two where the collateralization is more sparse (rostral and caudal to motor nuclei, respectively. The degree of collateralization in different segments was reconstructed in retrogradely labeled afferent fibers in the rat. Nerve volleys evoked in peripheral nerves by electrical stimulation of the dorsal columns within these regions were used as a measure of the excitability of the stimulated fibers. Potent increases in the excitability were evoked by polarization above motor nuclei and Clarke's column, both during constant direct current (DC) polarization (1 µA for 1 min) and for at least 30 min following DC polarization. Smaller excitability increases occurred during the polarization within other regions and were thereafter either absent or rapidly declined after its termination. The postpolarization increases in excitability were counteracted by the GABAA receptor antagonist bicuculline and the α5GABAA extrasynaptic receptor antagonist L655708 and enhanced by the GABAA receptor agonist muscimol and by ionophoretically applied GABA. As extrasynaptic α5GABAA receptors have been found close to Na channels within branching points, these results are consistent with the involvement of branching points in the induction of the sustained postpolarization increases in fiber excitability.NEW & NOTEWORTHY Polarization of sensory fibers traversing dorsal columns of the spinal cord may considerably increase the excitability of these fibers. We show that this involves the effects of current at branching points of afferent fibers and depends on extrasynaptic effects of GABA. These results contribute to our understanding of the mechanism underlying plasticity of activation of nerve fibers and may be used to increase the effectiveness of epidural stimulation in humans and recovery of spinal functions.
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Affiliation(s)
- Yaqing Li
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Krishnapriya Hari
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.,Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute and Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Ingela Hammar
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
| | - Elzbieta Jankowska
- Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
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5
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Cui J, Wang J, Bai W. Innervated Properties of Acupuncture Points LI 4 and LR 3 in the Rat: Neural Pathway Tracing with Cholera Toxin Subunit B. Med Acupunct 2019; 31:169-175. [PMID: 31312288 DOI: 10.1089/acu.2019.1334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Objective: Increasing evidence from acupuncture research suggests that the nervous system corresponds closely with classical acupuncture points. The aim of this research was to provide neuroanatomical evidence for revealing the innervated properties of different acupuncture points through comparing the sensory and motor pathways associated with Hegu (LI 4) and Taichong (LR 3) in rat extremities. Materials and Methods: Cholera toxin subunit B (CTB) was injected into LI 4 and LR 3 in different rats, and CTB neural labeling was examined using fluorescent immunohistochemistry and observed under fluorescent microscopy in the corresponding areas from the peripheral nervous system to the central nervous system, including the dorsal root ganglia (DRG), spinal cord, and brainstem. Results: When LI 4 was injected with CTB, CTB-labeled sensory neurons ranged from C-5 to T-1 DRG, and their transganglionic axons terminated in the C-5 to C-8 spinal dorsal horn as far as the cuneate nucleus, while labeled motor neurons were located in the C-7 to T-1 spinal ventral horn. In contrast, similar neural labeling was observed for LR 3 CTB injection, with an orderly arrangement in the L-3 to L-5 DRG, L-3 to L-5 spinal dorsal horn, gracile nucleus, and L-4 to L-6 spinal ventral horn. Conclusions: The present results provide further evidence to aid understanding of the differential innervation of acupuncture points LI 4 and LR 3. This innervation establishes its connection with the nervous system in a distinct segmental and regional pattern through the spinal sensory and motor pathways.
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Affiliation(s)
- Jingjing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Jia Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
| | - Wanzhu Bai
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing, China
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6
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Mueller PJ, Clifford PS, Crandall CG, Smith SA, Fadel PJ. Integration of Central and Peripheral Regulation of the Circulation during Exercise: Acute and Chronic Adaptations. Compr Physiol 2017; 8:103-151. [DOI: 10.1002/cphy.c160040] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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7
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Panneton WM, Pan B, Gan Q. Somatotopy in the Medullary Dorsal Horn As a Basis for Orofacial Reflex Behavior. Front Neurol 2017; 8:522. [PMID: 29066998 PMCID: PMC5641296 DOI: 10.3389/fneur.2017.00522] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 09/19/2017] [Indexed: 11/24/2022] Open
Abstract
The somatotopy of the trigeminocervical complex of the rat was defined as a basis for describing circuitry for reflex behaviors directed through the facial motor nucleus. Thus, transganglionic transport of horseradish peroxidase conjugates applied to individual nerves/peripheral receptive fields showed that nerves innervating oropharyngeal structures projected most rostrally, followed by nerves innervating snout, periocular, and then periauricular receptive fields most caudally. Nerves innervating mucosae or glabrous receptive fields terminated densely in laminae I, II, and V of the trigeminocervical complex, while those innervating hairy skin terminated in laminae I-V. Projections to lamina II exhibited the most focused somatotopy when individual cases were compared. Retrograde transport of FluoroGold (FG) deposited into the facial motor nucleus resulted in labeled neurons almost solely in lamina V of the trigeminocervical complex. The distribution of these labeled neurons paralleled the somatotopy of primary afferent fibers, e.g., those labeled after FG injections into a functional group of motoneurons innervating lip musculature were found most rostrally while those labeled after injections into motoneurons innervating snout, periocular and preauricular muscles, respectively, were found at progressively more caudal levels. Anterograde transport of injections of biotinylated dextran amine into lamina V at different rostrocaudal levels of the trigeminocervical complex confirmed the notion that the somatotopy of orofacial sensory fields parallels the musculotopy of facial motor neurons. These data suggest that neurons in lamina V are important interneurons in a simple orofacial reflex circuit consisting of a sensory neuron, interneuron and motor neuron. Moreover, the somatotopy of primary afferent fibers from the head and neck confirms the "onion skin hypothesis" and suggests rostral cervical dermatomes blend seamlessly with "cranial dermatomes." The transition area between subnucleus interpolaris and subnucleus caudalis is addressed while the paratrigeminal nucleus is discussed as an interface between the somatic and visceral nervous systems.
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Affiliation(s)
- W. Michael Panneton
- Department of Anesthesiology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - BingBing Pan
- Department of Anesthesiology, School of Medicine, Washington University in St. Louis, St. Louis, MO, United States
- Department of Anesthesiology, Hunan Provincial People’s Hospital, Changsha, China
| | - Qi Gan
- Department of Pharmacological and Physiological Science, School of Medicine, Saint Louis University, St. Louis, MO, United States
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Rosa A, Freitas M, Rocha I, Chacur M. Gabapentin decreases microglial cells and reverses bilateral hyperalgesia and allodynia in rats with chronic myositis. Eur J Pharmacol 2017; 799:111-117. [DOI: 10.1016/j.ejphar.2017.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 01/26/2017] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
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9
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Functional Organization of Cutaneous and Muscle Afferent Synapses onto Immature Spinal Lamina I Projection Neurons. J Neurosci 2017; 37:1505-1517. [PMID: 28069928 DOI: 10.1523/jneurosci.3164-16.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/13/2016] [Accepted: 12/24/2016] [Indexed: 11/21/2022] Open
Abstract
It is well established that sensory afferents innervating muscle are more effective at inducing hyperexcitability within spinal cord circuits compared with skin afferents, which likely contributes to the higher prevalence of chronic musculoskeletal pain compared with pain of cutaneous origin. However, the mechanisms underlying these differences in central nociceptive signaling remain incompletely understood, as nothing is known about how superficial dorsal horn neurons process sensory input from muscle versus skin at the synaptic level. Using a novel ex vivo spinal cord preparation, here we identify the functional organization of muscle and cutaneous afferent synapses onto immature rat lamina I spino-parabrachial neurons, which serve as a major source of nociceptive transmission to the brain. Stimulation of the gastrocnemius nerve and sural nerve revealed significant convergence of muscle and cutaneous afferent synaptic input onto individual projection neurons. Muscle afferents displayed a higher probability of glutamate release, although short-term synaptic plasticity was similar between the groups. Importantly, muscle afferent synapses exhibited greater relative expression of Ca2+-permeable AMPARs compared with cutaneous inputs. In addition, the prevalence and magnitude of spike timing-dependent long-term potentiation were significantly higher at muscle afferent synapses, where it required Ca2+-permeable AMPAR activation. Collectively, these results provide the first evidence for afferent-specific properties of glutamatergic transmission within the superficial dorsal horn. A larger propensity for activity-dependent strengthening at muscle afferent synapses onto developing spinal projection neurons could contribute to the enhanced ability of these sensory inputs to sensitize central nociceptive networks and thereby evoke persistent pain in children following injury.SIGNIFICANCE STATEMENT The neurobiological mechanisms underlying the high prevalence of chronic musculoskeletal pain remain poorly understood, in part because little is known about why sensory neurons innervating muscle appear more capable of sensitizing nociceptive pathways in the CNS compared with skin afferents. The present study identifies, for the first time, the functional properties of muscle and cutaneous afferent synapses onto immature lamina I projection neurons, which convey nociceptive information to the brain. Despite many similarities, an enhanced relative expression of Ca2+-permeable AMPA receptors at muscle afferent synapses drives greater LTP following repetitive stimulation. A preferential ability of the dorsal horn synaptic network to amplify nociceptive input arising from muscle is predicted to favor the generation of musculoskeletal pain following injury.
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10
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Zhang J, Hoheisel U, Klein T, Magerl W, Mense S, Treede RD. High-frequency modulation of rat spinal field potentials: effects of slowly conducting muscle vs. skin afferents. J Neurophysiol 2015; 115:692-700. [PMID: 26561600 DOI: 10.1152/jn.00415.2015] [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: 04/30/2015] [Accepted: 11/03/2015] [Indexed: 11/22/2022] Open
Abstract
Long-term potentiation (LTP) in rat spinal dorsal horn neurons was induced by electrical high-frequency stimulation (HFS) of afferent C fibers. LTP is generally assumed to be a key mechanism of spinal sensitization. To determine the contribution of skin and muscle afferents to LTP induction, the sural nerve (SU, pure skin nerve) or the gastrocnemius-soleus nerve (GS, pure muscle nerve) were stimulated individually. As a measure of spinal LTP, C-fiber-induced synaptic field potentials (SFPs) evoked by the GS and by the SU were recorded in the dorsal horn. HFS induced a sustained increase of SFPs of the same nerve for at least 3 h, indicating the elicitation of homosynaptic nociceptive spinal LTP. LTP after muscle nerve stimulation (HFS to GS) was more pronounced (increase to 248%, P < 0.05) compared with LTP after skin nerve stimulation (HFS applied to SU; increase to 151% of baseline, P < 0.05). HFS applied to GS also increased the SFPs of the unconditioned SU (heterosynaptic LTP) significantly, whereas HFS applied to SU had no significant impact on the SFP evoked by the GS. Collectively, the data indicate that HFS of a muscle or skin nerve evoked nociceptive spinal LTP with large effect sizes for homosynaptic LTP (Cohen's d of 0.8-1.9) and small to medium effect sizes for heterosynaptic LTP (Cohen's d of 0.4-0.65). The finding that homosynaptic and heterosynaptic LTP after HFS of the muscle nerve were more pronounced than those after HFS of a skin nerve suggests that muscle pain may be associated with more extensive LTP than cutaneous pain.
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Affiliation(s)
- Juanjuan Zhang
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and
| | - Ulrich Hoheisel
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and
| | - Thomas Klein
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and Mundipharma Research GmbH & Co., Limburg, Germany
| | - Walter Magerl
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and
| | - Siegfried Mense
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and
| | - Rolf-Detlef Treede
- Chair of Neurophysiology, Centre for Biomedicine and Medical Technology (CBTM), Medical Faculty Mannheim, Heidelberg University, Germany; and
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11
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Bui TV, Stifani N, Panek I, Farah C. Genetically identified spinal interneurons integrating tactile afferents for motor control. J Neurophysiol 2015; 114:3050-63. [PMID: 26445867 DOI: 10.1152/jn.00522.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/28/2015] [Indexed: 11/22/2022] Open
Abstract
Our movements are shaped by our perception of the world as communicated by our senses. Perception of sensory information has been largely attributed to cortical activity. However, a prior level of sensory processing occurs in the spinal cord. Indeed, sensory inputs directly project to many spinal circuits, some of which communicate with motor circuits within the spinal cord. Therefore, the processing of sensory information for the purpose of ensuring proper movements is distributed between spinal and supraspinal circuits. The mechanisms underlying the integration of sensory information for motor control at the level of the spinal cord have yet to be fully described. Recent research has led to the characterization of spinal neuron populations that share common molecular identities. Identification of molecular markers that define specific populations of spinal neurons is a prerequisite to the application of genetic techniques devised to both delineate the function of these spinal neurons and their connectivity. This strategy has been used in the study of spinal neurons that receive tactile inputs from sensory neurons innervating the skin. As a result, the circuits that include these spinal neurons have been revealed to play important roles in specific aspects of motor function. We describe these genetically identified spinal neurons that integrate tactile information and the contribution of these studies to our understanding of how tactile information shapes motor output. Furthermore, we describe future opportunities that these circuits present for shedding light on the neural mechanisms of tactile processing.
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Affiliation(s)
- Tuan V Bui
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada; Center for Neural Dynamics, University of Ottawa, Ottawa, Ontario, Canada; and
| | - Nicolas Stifani
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Izabela Panek
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Carl Farah
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
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12
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Panneton WM, Gan Q, Ariel M. Injections of Algesic Solutions into Muscle Activate the Lateral Reticular Formation: A Nociceptive Relay of the Spinoreticulothalamic Tract. PLoS One 2015; 10:e0130939. [PMID: 26154308 PMCID: PMC4496070 DOI: 10.1371/journal.pone.0130939] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/26/2015] [Indexed: 02/07/2023] Open
Abstract
Although musculoskeletal pain disorders are common clinically, the central processing of muscle pain is little understood. The present study reports on central neurons activated by injections of algesic solutions into the gastrocnemius muscle of the rat, and their subsequent localization by c-Fos immunohistochemistry in the spinal cord and brainstem. An injection (300μl) of an algesic solution (6% hypertonic saline, pH 4.0 acetate buffer, or 0.05% capsaicin) was made into the gastrocnemius muscle and the distribution of immunolabeled neurons compared to that obtained after control injections of phosphate buffered saline [pH 7.0]. Most labeled neurons in the spinal cord were found in laminae IV-V, VI, VII and X, comparing favorably with other studies, with fewer labeled neurons in laminae I and II. This finding is consistent with the diffuse pain perception due to noxious stimuli to muscles mediated by sensory fibers to deep spinal neurons as compared to more restricted pain localization during noxious stimuli to skin mediated by sensory fibers to superficial laminae. Numerous neurons were immunolabeled in the brainstem, predominantly in the lateral reticular formation (LRF). Labeled neurons were found bilaterally in the caudalmost ventrolateral medulla, where neurons responsive to noxious stimulation of cutaneous and visceral structures lie. Immunolabeled neurons in the LRF continued rostrally and dorsally along the intermediate reticular nucleus in the medulla, including the subnucleus reticularis dorsalis caudally and the parvicellular reticular nucleus more rostrally, and through the pons medial and lateral to the motor trigeminal nucleus, including the subcoerulear network. Immunolabeled neurons, many of them catecholaminergic, were found bilaterally in the nucleus tractus solitarii, the gracile nucleus, the A1 area, the CVLM and RVLM, the superior salivatory nucleus, the nucleus locus coeruleus, the A5 area, and the nucleus raphe magnus in the pons. The external lateral and superior lateral subnuclei of the parabrachial nuclear complex were consistently labeled in experimental data, but they also were labeled in many control cases. The internal lateral subnucleus of the parabrachial complex was labeled moderately. Few immunolabeled neurons were found in the medial reticular formation, however, but the rostroventromedial medulla was labeled consistently. These data are discussed in terms of an interoceptive, multisynaptic spinoreticulothalamic path, with its large receptive fields and role in the motivational-affective components of pain perceptions.
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Affiliation(s)
- W. Michael Panneton
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO, United States of America
- * E-mail:
| | - Qi Gan
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO, United States of America
| | - Michael Ariel
- Department of Pharmacological and Physiological Science, Saint Louis University, St. Louis, MO, United States of America
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Laurin J, Pertici V, Dousset E, Marqueste T, Decherchi P. Group III and IV muscle afferents: Role on central motor drive and clinical implications. Neuroscience 2015; 290:543-51. [DOI: 10.1016/j.neuroscience.2015.01.065] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 12/12/2022]
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Koizumi H, Goto S, Okita S, Morigaki R, Akaike N, Torii Y, Harakawa T, Ginnaga A, Kaji R. Spinal Central Effects of Peripherally Applied Botulinum Neurotoxin A in Comparison between Its Subtypes A1 and A2. Front Neurol 2014; 5:98. [PMID: 25002857 PMCID: PMC4066301 DOI: 10.3389/fneur.2014.00098] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 05/31/2014] [Indexed: 01/28/2023] Open
Abstract
Because of its unique ability to exert long-lasting synaptic transmission blockade, botulinum neurotoxin A (BoNT/A) is used to treat a wide variety of disorders involving peripheral nerve terminal hyperexcitability. However, it has been a matter of debate whether this toxin has central or peripheral sites of action. We employed a rat model in which BoNT/A1 or BoNT/A2 was unilaterally injected into the gastrocnemius muscle. On time-course measurements of compound muscle action potential (CMAP) amplitudes after injection of BoNT/A1 or BoNT/A2 at doses ranging from 1.7 to 13.6 U, CMAP amplitude for the ipsilateral hind leg was markedly decreased on the first day, and this muscle flaccidity persisted up to the 14th day. Of note, both BoNT/A1 and BoNT/A2 administrations also resulted in decreased CMAP amplitudes for the contralateral leg in a dose-dependent manner ranging from 1.7 to 13.6 U, and this muscle flaccidity increased until the fourth day and then slowly recovered. Immunohistochemical results revealed that BoNT/A-cleaved synaptosomal-associated protein of 25 kDa (SNAP-25) appeared in the bilateral ventral and dorsal horns 4 days after injection of BoNT/A1 (10 U) or BoNT/A2 (10 U), although there seemed to be a wider spread of BoNT/A-cleaved SNAP-25 associated with BoNT/A1 than BoNT/A2 in the contralateral spinal cord. This suggests that the catalytically active BoNT/A1 and BoNT/A2 were axonally transported via peripheral motor and sensory nerves to the spinal cord, where they spread through a transcytosis (cell-to-cell trafficking) mechanism. Our results provide evidence for the central effects of intramuscularly administered BoNT/A1 and BoNT/A2 in the spinal cord, and a new insight into the clinical effects of peripheral BoNT/A applications.
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Affiliation(s)
- Hidetaka Koizumi
- Department of Clinical Neuroscience, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan ; Department of Motor Neuroscience and Neurotherapeutics, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan
| | - Satoshi Goto
- Department of Motor Neuroscience and Neurotherapeutics, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan
| | - Shinya Okita
- Department of Motor Neuroscience and Neurotherapeutics, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan
| | - Ryoma Morigaki
- Department of Motor Neuroscience and Neurotherapeutics, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan
| | - Norio Akaike
- Research Division for Life Science, Kumamoto Health Science University , Kumamoto , Japan
| | - Yasushi Torii
- The Chemo-Sero-Therapeutic Research Institute (KAKETSUKEN) , Kumamoto , Japan ; Graduate School of Medicine, Osaka University , Osaka , Japan
| | - Tetsuhiro Harakawa
- The Chemo-Sero-Therapeutic Research Institute (KAKETSUKEN) , Kumamoto , Japan
| | - Akihiro Ginnaga
- The Chemo-Sero-Therapeutic Research Institute (KAKETSUKEN) , Kumamoto , Japan
| | - Ryuji Kaji
- Department of Clinical Neuroscience, Institute of Health Biosciences, Graduate School of Medical Sciences, University of Tokushima , Tokushima , Japan
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Panneton WM, Gan Q. Direct reticular projections of trigeminal sensory fibers immunoreactive to CGRP: potential monosynaptic somatoautonomic projections. Front Neurosci 2014; 8:136. [PMID: 24926231 PMCID: PMC4046267 DOI: 10.3389/fnins.2014.00136] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 05/14/2014] [Indexed: 11/30/2022] Open
Abstract
Few trigeminal sensory fibers project centrally beyond the trigeminal sensory complex, with only projections of fibers carried in its sensory anterior ethmoidal (AEN) and intraoral nerves described. Fibers of the AEN project into the brainstem reticular formation where immunoreactivity against substance P and CGRP are found. We investigated whether the source of these peptides could be from trigeminal ganglion neurons by performing unilateral rhizotomies of the trigeminal root and looking for absence of label. After an 8–14 days survival, substance P immunoreactivity in the trigeminal sensory complex was diminished, but we could not conclude that the sole source of this peptide in the lateral parabrachial area and lateral reticular formation arises from primary afferent fibers. Immunoreactivity to CGRP after rhizotomy however was greatly diminished in the trigeminal sensory complex, confirming the observations of others. Moreover, CGRP immunoreactivity was nearly eliminated in fibers in the lateral parabrachial area, the caudal ventrolateral medulla, both the peri-ambiguus and ventral parts of the rostral ventrolateral medulla, in the external formation of the nucleus ambiguus, and diminished in the caudal pressor area. The nearly complete elimination of CGRP in the lateral reticular formation after rhizotomy suggests this peptide is carried in primary afferent fibers. Moreover, the arborization of CGRP immunoreactive fibers in these areas mimics that of direct projections from the AEN. Since electrical stimulation of the AEN induces cardiorespiratory adjustments including an apnea, peripheral vasoconstriction, and bradycardia similar to those seen in the mammalian diving response, we suggest these perturbations of autonomic behavior are enhanced by direct somatic primary afferent projections to these reticular neurons. We believe this to be first description of potential direct somatoautonomic projections to brainstem neurons regulating autonomic activity.
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Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University Medical School , St. Louis, MO, USA
| | - Qi Gan
- Department of Pharmacological and Physiological Science, St. Louis University Medical School , St. Louis, MO, USA
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Quiroz-González S, Segura-Alegría B, Jiménez-Estrada I. Depressing effect of electroacupuncture on the spinal non-painful sensory input of the rat. Exp Brain Res 2014; 232:2721-9. [DOI: 10.1007/s00221-014-3965-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 04/12/2014] [Indexed: 01/27/2023]
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17
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Smith SA, Downey RM, Williamson JW, Mizuno M. Autonomic dysfunction in muscular dystrophy: a theoretical framework for muscle reflex involvement. Front Physiol 2014; 5:47. [PMID: 24600397 PMCID: PMC3927082 DOI: 10.3389/fphys.2014.00047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 01/24/2014] [Indexed: 01/16/2023] Open
Abstract
Muscular dystrophies are a heterogeneous group of genetically inherited disorders whose most prominent clinical feature is progressive degeneration of skeletal muscle. In several forms of the disease, the function of cardiac muscle is likewise affected. The primary defect in this group of diseases is caused by mutations in myocyte proteins important to cellular structure and/or performance. That being stated, a growing body of evidence suggests that the development of autonomic dysfunction may secondarily contribute to the generation of skeletal and cardio-myopathy in muscular dystrophy. Indeed, abnormalities in the regulation of both sympathetic and parasympathetic nerve activity have been reported in a number of muscular dystrophy variants. However, the mechanisms mediating this autonomic dysfunction remain relatively unknown. An autonomic reflex originating in skeletal muscle, the exercise pressor reflex, is known to contribute significantly to the control of sympathetic and parasympathetic activity when stimulated. Given the skeletal myopathy that develops with muscular dystrophy, it is logical to suggest that the function of this reflex might also be abnormal with the pathogenesis of disease. As such, it may contribute to or exacerbate the autonomic dysfunction that manifests. This possibility along with a basic description of exercise pressor reflex function in health and disease are reviewed. A better understanding of the mechanisms that possibly underlie autonomic dysfunction in muscular dystrophy may not only facilitate further research but could also lead to the identification of new therapeutic targets for the treatment of muscular dystrophy.
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Affiliation(s)
- Scott A Smith
- Department of Health Care Sciences, University of Texas Southwestern Medical Center Dallas, TX, USA ; Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Ryan M Downey
- Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Jon W Williamson
- Department of Health Care Sciences, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Masaki Mizuno
- Department of Health Care Sciences, University of Texas Southwestern Medical Center Dallas, TX, USA
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Cui JJ, Ha LJ, Zhu XL, Shi H, Wang FC, Jing XH, Bai WZ. Neuroanatomical basis for acupuncture point PC8 in the rat: neural tracing study with cholera toxin subunit B. Acupunct Med 2013; 31:389-94. [PMID: 23956381 DOI: 10.1136/acupmed-2013-010400] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES This study was performed to investigate the innervations related to acupuncture point PC8 in rats using a neural tracing technique. METHODS After 6 μL of 1% cholera toxin subunit B (CTB) was injected into the site between the second and third metacarpal bone in rats, a corresponding site to acupuncture point PC8 in the human body, CTB labelling was examined with immunofluorescence and immunohistochemistry in the dorsal root ganglia (DRG), spinal cord and brainstem. RESULTS All CTB labelling appeared on the ipsilateral side of the injection. The labelled sensory neurons distributed from cervical (C)6 to thoracic (T)1 DRG, while the labelled motor neurons were located on the dorsolateral part of the spinal ventral horn ranging from the C6 to T1 segments. In addition, the transganglionically-labelled axonal terminals were found to be dense in the medial part of laminae 3-4 from C6 to the T1 spinal dorsal horn, as far as in the cuneate nucleus. CONCLUSIONS These results indicate that sensory and motor neurons associated with PC8 distribute in a distinct segmental pattern. The sensory information from PC8 could be transganglionically transported to the spinal dorsal horn and cuneate nucleus.
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Affiliation(s)
- Jing-Jing Cui
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, , Beijing, China
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Taguchi T, Yasui M, Kubo A, Abe M, Kiyama H, Yamanaka A, Mizumura K. Nociception originating from the crural fascia in rats. Pain 2013; 154:1103-14. [DOI: 10.1016/j.pain.2013.03.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 02/21/2013] [Accepted: 03/12/2013] [Indexed: 10/26/2022]
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Okamoto K, Thompson R, Katagiri A, Bereiter DA. Estrogen status and psychophysical stress modify temporomandibular joint input to medullary dorsal horn neurons in a lamina-specific manner in female rats. Pain 2013; 154:1057-64. [PMID: 23607965 DOI: 10.1016/j.pain.2013.03.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 02/20/2013] [Accepted: 03/08/2013] [Indexed: 12/12/2022]
Abstract
Estrogen status and psychological stress contribute to the expression of several chronic pain conditions including temporomandibular muscle and joint disorders (TMJD). Sensory neurons that supply the temporomandibular joint (TMJ) region terminate in laminae I and V of the spinal trigeminal nucleus (Vc/C1-2 region); however, little is known about lamina-specificity and environmental influences on the encoding properties of TMJ brainstem neurons. To test the hypothesis that Vc/C1-2 neurons integrate both interoceptive and exteroceptive signals relevant for TMJ nociception, we recorded TMJ-evoked activity in superficial and deep laminae of ovariectomized rats under high and low estradiol (E2) and stress conditions. Rats received daily injections of low (LE) or high (HE) dose E2 and were subjected to forced swim (FS) or sham swim conditioning for 3days. The results revealed marked lamina-specificity in that HE rats displayed enhanced TMJ-evoked activity in superficial, but not deep, laminae independent of stress conditioning. By contrast, FS conditioned rats displayed increased background firing and TMJ-evoked activity of neurons in deep, but not superficial, laminae independent of E2 status. FS also enhanced TMJ-evoked masseter muscle activity and suggested the importance of deep dorsal horn neurons in mediating evoked jaw muscle activity. In conclusion, E2 status and psychophysical stress play a significant role in modifying the encoding properties of TMJ-responsive medullary dorsal horn neurons with a marked lamina-specificity.
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Affiliation(s)
- Keiichiro Okamoto
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, SE Minneapolis, MN 55455, USA.
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21
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Tetrodotoxin-resistant fibres and spinal Fos expression: differences between input from muscle and skin. Exp Brain Res 2012. [PMID: 23178907 DOI: 10.1007/s00221-012-3337-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nociceptive information from muscle and skin is differently processed at many levels of the central nervous system. In most articles on this issue, noxious stimuli were used that also excited non-nociceptive receptors. The effects of a pure nociceptive input from muscle or skin on spinal neurones are largely unknown. The aim of the study was to find out whether the Fos-protein expression in dorsal horn neurones induced by an exclusively nociceptive muscle input differs from that of the skin. Fos-proteins are transcription factors that regulate neuronal gene expression and induce neuroplastic effects that are involved in the development of chronic pain. A pure nociceptive input was achieved by tetrodotoxin (TTX) that is known to block all TTX-sensitive afferents and leave the TTX-resistant (TTX-r), presumably nociceptive, afferent fibres intact. We studied the c-Fos and FosB expression in the spinal cord following electrical stimulation of TTX-r afferent fibres in the gastrocnemius-soleus nerve (muscle) and compared it to the sural nerve (skin). In the spinal dorsal horn, the main effect of a TTX-r input from muscle was an increase in FosB (P < 0.05), but not in c-Fos expression (P = 0.51). In contrast, an input from the skin induced both FosB (P < 0.01) and c-Fos expression (P < 0.05). The data indicate that in the spinal, dorsal horn nociceptive input from skin and muscle has different effects on the Fos expression. The only effect of muscle input was an increase in FosB expression while skin input increased both c-Fos and FosB expression.
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22
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Chen YK, Lei J, Jin L, Tan YX, You HJ. Dynamic variations of c-Fos expression in the spinal cord exposed to intramuscular hypertonic saline-induced muscle nociception. Eur J Pain 2012; 17:336-46. [DOI: 10.1002/j.1532-2149.2012.00207.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2012] [Indexed: 12/19/2022]
Affiliation(s)
- Y.-K. Chen
- Center for Biomedical Research on Pain (CBRP); College of Medicine; Xi'an Jiaotong University; China
| | - J. Lei
- Center for Biomedical Research on Pain (CBRP); College of Medicine; Xi'an Jiaotong University; China
| | - L. Jin
- Department of Neurosurgery; The First Hospital affiliated to Xi'an Medical College; China
| | - Y.-X. Tan
- Center for Biomedical Research on Pain (CBRP); College of Medicine; Xi'an Jiaotong University; China
| | - H.-J. You
- Center for Biomedical Research on Pain (CBRP); College of Medicine; Xi'an Jiaotong University; China
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IB4-saporin attenuates acute and eliminates chronic muscle pain in the rat. Exp Neurol 2011; 233:859-65. [PMID: 22206923 DOI: 10.1016/j.expneurol.2011.12.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 11/02/2011] [Accepted: 12/11/2011] [Indexed: 12/29/2022]
Abstract
The function of populations of nociceptors in muscle pain syndromes remain poorly understood. We compared the contribution of two major classes, isolectin B4-positive (IB4(+)) and IB4-negative (IB4(-)) nociceptors, in acute and chronic inflammatory and ergonomic muscle pain. Baseline mechanical nociceptive threshold was assessed in the gastrocnemius muscle of rats treated with IB4-saporin, which selectively destroys IB4(+) nociceptors. Rats were then submitted to models of acute inflammatory (intramuscular carrageenan)- or ergonomic intervention (eccentric exercise or vibration)-induced muscle pain, and each of the three models also evaluated for the transition from acute to chronic pain, manifest as prolongation of prostaglandin E2 (PGE(2))-induced hyperalgesia, after recovery from the hyperalgesia induced by acute inflammation or ergonomic interventions. IB4-saporin treatment did not affect baseline mechanical nociceptive threshold. However, compared to controls, IB4-saporin treated rats exhibited shorter duration mechanical hyperalgesia in all three models and attenuated peak hyperalgesia in the ergonomic pain models. And, IB4-saporin treatment completely prevented prolongation of PGE(2)-induced mechanical hyperalgesia. Thus, IB4(+) and IB4(-) neurons contribute to acute muscle hyperalgesia induced by diverse insults. However, only IB4+ nociceptors participate in the long term consequence of acute hyperalgesia.
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Takahashi Y, Ohtori S, Takahashi K. Somatotopic organization of lumbar muscle-innervating neurons in the ventral horn of the rat spinal cord. J Anat 2010; 216:489-95. [PMID: 20136668 DOI: 10.1111/j.1469-7580.2009.01203.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The ventral horn of the rat spinal cord was investigated with respect to the somatotopic organization of the motor neurons that innervate the lumbar muscles. Neurotracer 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) was applied to specific sites in lumbar muscles. Spinal cord segments at L1 through L4 levels were cut into 40-mum serial transverse sections. Labeled neurons were located in the ventromedial nucleus (VM) and lateromedial nucleus (LM) nuclei of Rexed's lamina IX. Motor neurons innervating the m. interspinales lumborum and m. multifidus were without exception present in the VM, whereas all motor neurons innervating the m. rectus abdominis were present in the LM. Forty percent of motor neurons innervating the m. quadratus lumborum were present in the VM and the other 60% were in the LM. Although most of the motor neurons innervating the m. psoas major were present in the LM, a few labeled neurons existed in the VM. These results suggest that the border zone demarcating the areas of innervation of the dorsal and ventral rami of spinal nerves crosses the m. quadratus lumborum.
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Affiliation(s)
- Yuzuru Takahashi
- Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
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Distinct central representations for sensory fibers innervating either the conjunctiva or cornea of the rat. Exp Eye Res 2009; 90:388-96. [PMID: 20004193 DOI: 10.1016/j.exer.2009.11.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 11/19/2009] [Accepted: 11/30/2009] [Indexed: 10/20/2022]
Abstract
The laminar sheet of epithelium (e.g., skin and mucous membrane) enclosing our bodies is represented in the dorsal horns of the medulla and spinal cord. The eyeball however indents this laminar sheet and is shrouded by different layers: the cornea/sclera, the conjunctiva, and hairy skin. This involution of the orb confounds defining the central representation of the cornea and its surrounding mucosa and skin. We used herein the transganglionic transport of a cocktail of HRP conjugated to cholera toxin and wheat germ agglutinin to determine the central representation of these epithelia in the dorsal horns of the rat. The HRP cocktail was injected either into the stroma of the cornea, the mucosa of the conjunctiva, or the supraorbital and infraorbital nerves. Injections of the cornea produced dense label in the interstitial islands in the ventral medullary dorsal horn (MDH), probably lamina I, and in neuropil in the ventromedial tip of the MDH, probably lamina II. There sometimes was variable, diffuse label in the C1 dorsal horn after corneal injections but more rostral parts of the trigeminal sensory complex were never labeled. Injections of the conjunctiva densely labeled laminae I-III in the C1 dorsal horn, while laminae IV-V were diffusely labeled. Sparser reaction product also was seen in lamina I in positions similar to the cornea projection. Label was seen ventrally in subnuclei interpolaris and oralis, as well as the principal trigeminal nucleus. Projections of the infraorbital nerve included all laminae in the trigeminocervical complex as well as large portions of the rostral subnuclei in the spinal trigeminal nucleus. The projections of the supraorbital nerve were similar, but were restricted to ventral parts of the trigeminal sensory complex. In other cases the cornea was injected either after cutting the supraorbital and infraorbital nerves or the conjunctiva was injected after enucleating the eyeball. Any reaction product from corneal injections was reduced dramatically in the C1 dorsal horn after transection of the infraorbital and supraorbital nerves. Injecting the conjunctiva after enucleating the eyeball densely labeled the C1 projection to the dorsal horn, a small patch in lamina I in the MDH, as well as the rostral trigeminal complex. We propose that the cornea has but a single representation in the trigeminocervical complex in its ventral part near the caudal end of the medulla. We also propose the palpebral conjunctiva mucosa is represented in the C1 dorsal horn, and speculate that the bulbar conjunctiva overlaps with that of the cornea in lamina I. We discuss these projections in relation to the circuitry for the supraorbital-evoked and corneal-evoked blink reflexes. The relationship of the cornea and conjunctiva is intimate, and investigators must be very careful when attempting to stimulate them in isolation.
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Furuta S, Shimizu T, Narita M, Matsumoto K, Kuzumaki N, Horie S, Suzuki T, Narita M. Subdiaphragmatic vagotomy promotes nociceptive sensitivity of deep tissue in rats. Neuroscience 2009; 164:1252-62. [PMID: 19772896 DOI: 10.1016/j.neuroscience.2009.09.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2009] [Accepted: 09/10/2009] [Indexed: 11/30/2022]
Abstract
To verify whether vagal dysfunction is associated with chronic pain, we evaluated the effects of subdiaphragmatic vagotomy (vgx) on the sensitivity toward noxious stimuli in rats. Vgx rats showed sustained hyperalgesia in the gastrocnemius muscle without tissue damage (no increase in vgx-induced plasma creatine phosphokinase or lactose dehydrogenase levels) accompanied by hypersensitivity to colonic distension. We found a dramatic increase in the levels of metabotropic glutamate receptor 5, protein kinase C (PKC) gamma and phosphorylated-PKCgamma within the spinal cord dorsal horn in vgx rats, which suggests that vgx may evoke sensory nerve plasticity. Morphine produced a dose-dependent increase in the withdrawal threshold in both vgx and sham-operated rats, but the effect of a lower dose in vgx rats was weaker than that in sham-operated rats. Muscle hyperalgesia in vgx rats was also attenuated by gabapentin and amitriptyline, but was not affected by diclofenac, dexamethasone or diazepam. These findings indicate that subdiaphragmatic vagal dysfunction caused chronic muscle hyperalgesia accompanied by visceral pain and both gabapentin and amitriptyline were effective for subdiaphragmatic vagotomy-induced pain, which are partially similar to fibromyalgia syndrome. Furthermore, this chronic muscle pain may result from nociceptive neuroplasticity of the spinal cord dorsal horn.
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Affiliation(s)
- S Furuta
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo, 142-8501, Japan
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Hollandsworth MP, DiNovo KM, McCulloch PF. Unmyelinated fibers of the anterior ethmoidal nerve in the rat co-localize with neurons in the medullary dorsal horn and ventrolateral medulla activated by nasal stimulation. Brain Res 2009; 1298:131-44. [PMID: 19732757 DOI: 10.1016/j.brainres.2009.08.077] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Accepted: 08/19/2009] [Indexed: 11/18/2022]
Abstract
The anterior ethmoidal nerve (AEN) innervates the nasal passages and external nares, and serves as the afferent limb of the nasopharyngeal and diving responses. However, although 65% of the AEN is composed of unmyelinated fibers, it has not been determined whether this afferent signal is carried by unmyelinated or myelinated fibers. We used the transganglionic tracers WGA-HRP, IB4-HRP, and CTB-HRP to trace the central projections of the AEN of the rat. Interpretation of the labeling patterns suggests that AEN unmyelinated fibers project primarily to the ventral tip of the ipsilateral medullary dorsal horn (MDH) at the level of the area postrema. Other unmyelinated projections were to the ventral paratrigeminal nucleus and ventrolateral medulla, specifically the Bötzinger and RVLM/C1 regions. Myelinated AEN fibers projected to the ventral paratrigeminal and mesencephalic trigeminal nuclei. Stimulating the nasal passages of urethane-anesthetized rats with ammonia vapors produced the nasopharyngeal response that included apnea, bradycardia and an increase in arterial blood pressure. Central projections of the AEN co-localized with neurons within both MDH and RVLM/C1 that were activated by nasal stimulation. Within the ventral MDH the density of AEN terminal projections positively correlated with the rostral-caudal location of activated neurons, especially at and just caudal to the obex. We conclude that unmyelinated AEN terminal projections are involved in the activation of neurons in the MDH and ventrolateral medulla that participate in the nasopharyngeal response in the rat. We also found that IB4-HRP was a much less robust tracer than WGA-HRP.
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Affiliation(s)
- Michael P Hollandsworth
- Department of Physiology, Midwestern University, 555 31st Street, Downers Grove, IL 60515, USA
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28
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Shin DS, Kim EH, Song KY, Hong HJ, Kong MH, Hwang SJ. Neurochemical Characterization of the TRPV1-Positive Nociceptive Primary Afferents Innervating Skeletal Muscles in the Rats. J Korean Neurosurg Soc 2008; 43:97-104. [PMID: 19096612 DOI: 10.3340/jkns.2008.43.2.97] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Accepted: 01/14/2008] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Transient receptor potential vanilloid subfamily type 1 (TRPV1), a most specific marker of the nociceptive primary afferent, is expressed in peptidergic and non-pepetidergic primary afferents innervating skin and viscera. However, its expression in sensory fibers to skeletal muscle is not well known. In this study, we studied the neurochemical characteristics of TRPV1-positive primary afferents to skeletal muscles. METHODS Sprague-Dawley rats were injected with total 20 microl of 1% fast blue (FB) into the gastrocnemius and erector spinae muscle and animals were perfused 4 days after injection. FB-positive cells were traced in the L4-L5 (for gastrocnemius muscle) and L2-L4 (for erector spinae muscle) dorsal root ganglia. The neurochemical characteristics of the muscle afferents were studied with multiple immunofluorescence with TRPV1, calcitonin gene-related peptide (CGRP) and P2X(3). To identify spinal neurons responding to noxious stimulus to the skeletal muscle, 10% acetic acids were injected into the gastrocnemius and erector spinae muscles and expression of phospho extracellular signal-regulated kinase (pERK) in spinal cords were identified with immunohistochemical method. RESULTS TRPV1 was expressed in about 49% of muscle afferents traced from gastrocnemius and 40% of erector spinae. Sixty-five to 60% of TRPV1-positive muscles afferents also expressed CGRP. In contrast, expression of P2X(3) immnoreaction in TRPV1-positive muscle afferents were about 20%. TRPV1-positive primary afferents were contacted with spinal neurons expressing pERK after injection of acetic acid into the muscles. CONCLUSION It is consequently suggested that nociception from skeletal muscles are mediated by TRPV1-positive primary afferents and majority of them are also peptidergic.
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Affiliation(s)
- Dong Su Shin
- Department of Neurosurgery , Seoul Medical Center, Seoul, Korea
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29
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Lambertz D, Hoheisel U, Mense S. Influence of a chronic myositis on rat spinal field potentials evoked by TTX-resistant unmyelinated skin and muscle afferents. Eur J Pain 2007; 12:686-95. [PMID: 18078769 DOI: 10.1016/j.ejpain.2007.10.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/22/2007] [Accepted: 10/24/2007] [Indexed: 11/16/2022]
Abstract
A recent study of our group has shown that in the segments L4 and L5 of the rat, the synaptic field potentials (SFPs) evoked by tetrodotoxin-resistant (TTX-r, presumably nociceptive) muscle afferents differ in size and peak location from those of cutaneous afferents from the same body region [Lambertz D, Hoheisel U, Mense S. Distribution of synaptic field potentials induced by TTX-resistant skin and muscle afferents in rat segment L4 and L5. Neurosci Lett 2006;409:14-8]. Here, we investigated the influence of a muscle inflammation on the distribution of SFPs of TTX-r afferent fibres from muscle and skin in the thoracic and lumbar spinal cord. During a TTX block of the dorsal roots L3-L6, a skin nerve (sural, SU) or a muscle nerve (gastrocnemius-soleus, GS) were electrically stimulated at an intensity supramaximal for unmyelinated afferents and the SFPs recorded with tungsten microelectrodes. In control (non-inflamed) rats, the largest SFPs evoked by TTX-r GS afferents were recorded in laminae IV-VI with a maximum in segment L4, whereas the largest SU-induced SFPs were more superficially located with a maximum in L3. In chronic myositis animals, SFPs induced by GS TTX-r fibres exhibited significant decreases in lamina IV-VI of Th 12 and L5 as well as in lamina VII of L5. In contrast, SFPs evoked by SU TTX-r afferents showed significant increases in lamina IV-VI in L1 and in lamina VII in L4. The results demonstrate that a chronic myositis has a strong influence also on the synaptic effects of nociceptive afferents from the skin, which may explain the subjective cutaneous sensations during a pathological alteration of muscle.
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Affiliation(s)
- D Lambertz
- Institute of Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, D-69120 Heidelberg, Germany.
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30
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Majcher K, Tomanek B, Tuor UI, Jasinski A, Foniok T, Rushforth D, Hess G. Functional magnetic resonance imaging within the rat spinal cord following peripheral nerve injury. Neuroimage 2007; 38:669-76. [PMID: 17904387 DOI: 10.1016/j.neuroimage.2007.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 07/31/2007] [Accepted: 08/06/2007] [Indexed: 11/20/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) was used to detect the effects of graded peripheral nerve injury at the spinal level. Graded peripheral nerve injury in rats was accomplished by transection of nerves entering the spinal cord at the L3 and L4 levels of the spinal cord segments. Electrical stimulation of the hindpaw was used to elicit activity within the spinal cord. The stimulation experimental paradigm consisted of 62 functional images, 5 slices each, with a total of 3 rest and 2 stimulation periods. A 9.4 T MRI system and a quadrature volume rf coil covering the lumbar spinal cord were used for the fMRI study. Sets of fast spin echo images were acquired repeatedly following sham preparatory surgery under control conditions and in rats following sham surgery (pre nerve cut), followed by L3 nerve and then L4 nerve section. In rats with sham surgery, there was a significant activation within the dorsal horn of slices corresponding to L3 and L4 spinal cord segments. Following section of the L3 nerve, there was a reduction in the number of active voxels in the L3 and L4 spinal cord segments. The activation was reduced further by sectioning of the L4 nerve. Thus, following an increasing loss of axonal connections to the spinal cord, there was a decreasing number of active voxels within the spinal cord. The results demonstrate that spinal fMRI in the rat has sufficient sensitivity to detect within the spinal cord the effects of a graded reduction in peripheral connectivity.
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Affiliation(s)
- Katarzyna Majcher
- Institute of Nuclear Physics, Polish Academy of Sciences, Krakow, Poland
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31
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Taguchi T, John V, Hoheisel U, Mense S. Neuroanatomical pathway of nociception originating in a low back muscle (multifidus) in the rat. Neurosci Lett 2007; 427:22-7. [PMID: 17928140 DOI: 10.1016/j.neulet.2007.08.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/13/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
The neural mechanisms of low back pain (LBP) are still enigmatic. Presently, low back muscles are being discussed as an important source of LBP. Here, the neuroanatomical pathway of the nociceptive information from the caudal multifidus muscle (MF) was studied. True blue was injected into the MF at the level L5 to visualize the dorsal root ganglion (DRG) cells that supply this muscle. The distribution of the stained cells had a maximum in the DRG L3, not in L5. Injection of 5% formalin into the MF at levels L4 and L5 induced a significant increase in the number of c-Fos-immunoreactive (-ir) nuclei in the dorsal horn in many lumbar segments. Cells expressing c-Fos were particularly numerous in the most lateral part of the ipsilateral laminae I-II. The number of c-Fos-ir nuclei in the dorsal horn of segment L3 was significantly higher than that in segment L5. To visualize supraspinal projections, fluorogold (FG) was injected into the contralateral ventrolateral periaqueductal gray (vlPAG) 6 days prior to formalin or saline injection into the MF. The number of double-labeled dorsal horn neurons (FG-positive plus c-Fos-ir) in all lumbar segments was significantly higher in the formalin group than in the saline group. These results show that (1) the origin of the sensory supply of the MF is shifted two segments cranially relative to the location of the muscle, (2) the spinal cells processing nociceptive input from the caudal MF are widely distributed, and (3) the vlPAG is a supraspinal center of nociception from the MF.
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Affiliation(s)
- Toru Taguchi
- Department of Anatomy and Cell Biology, University of Heidelberg, Im Neuenheimer Feld 307, D-69120 Heidelberg, Germany
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Dessem D, Moritani M, Ambalavanar R. Nociceptive craniofacial muscle primary afferent neurons synapse in both the rostral and caudal brain stem. J Neurophysiol 2007; 98:214-23. [PMID: 17493918 DOI: 10.1152/jn.00990.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Limited information is available on muscle afferent neurons with fine fibers despite their presumed participation in musculoskeletal disorders, including temporomandibular disorders. To study these neurons, intracellular recordings were made from the central axons of slowly conducting muscle afferent neurons in anesthetized rats. After intraaxonal impalement, axons were characterized by masseter nerve stimulation, receptive field testing, muscle stretching and intramuscular injection of hypertonic saline. Intracellular recordings were made from 310 axons (conduction velocity: 6.5-60(M)/s, mean = 27.3(M)/s; following frequency: 27-250 Hz, mean = 110Hz). No neurons responded to cutaneous palpation or muscle stretching. Some axons (n = 34) were intracellularly stained with biotinamide. These neurons were classified as group II/III noxious mechanoreceptors because their mechanical threshold exceeded 15 mN, and conduction velocities ranged from 12 to 40.2(M)/s (mean = 25.3(M)/s). Two morphological types were recognized by using an object-based, three-dimensional colocalization methodology to locate synapses. One type (IIIHTM(Vp-Vc)) possessed axon collaterals that emerged along the entire main axon and synapsed in the trigeminal principal sensory nucleus and spinal trigeminal subnuclei oralis (Vo), interpolaris (Vi), and caudalis (Vc). A second type (IIIHTM(Vo-Vc)) possessed axon collaterals that synapsed only in caudal Vo, Vi, and Vc. Our previous studies show that muscle spindle afferent neurons are activated by innocuous stimuli and synapse in the rostral and caudal brain stem; here we demonstrate that nociceptive muscle mechanoreceptor afferent axons also synapse in rostral and caudal brain stem regions. Traditional dogma asserts that the most rostral trigeminal sensory complex exclusively processes innocuous somatosensory information, whereas caudal portions receive nociceptive sensory input; the data reported here do not support this paradigm.
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Affiliation(s)
- Dean Dessem
- Dept of Biomedical Sciences, University of Maryland, Baltimore, MD 21201, USA.
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Degtyarenko AM, Kaufman MP. Barosensory cells in the nucleus tractus solitarius receive convergent input from group III muscle afferents and central command. Neuroscience 2006; 140:1041-50. [PMID: 16626870 DOI: 10.1016/j.neuroscience.2006.02.050] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 02/09/2006] [Accepted: 02/23/2006] [Indexed: 11/23/2022]
Abstract
Some neural mechanism must prevent the full expression of the baroreceptor reflex during static exercise because arterial blood pressure increases even though the baroreceptors are functioning. Two likely candidates are central command and input from the thin fiber muscle afferents evoking the exercise pressor reflex. Recently, activation of the mesencephalic locomotor region, an anatomical locus for central command, was found to inhibit the discharge of nucleus tractus solitarius cells that were stimulated by arterial baroreceptors in decerebrated cats. In contrast, the effect of thin fiber muscle afferent input on the discharge of nucleus tractus solitarius cells stimulated by baroreceptors is not known. Consequently in decerebrated unanesthetized cats, we examined the responses of barosensory nucleus tractus solitarius cells to stimulation of thin fiber muscle afferents and to stimulation of the mesencephalic locomotor region, a maneuver which evoked fictive locomotion. We found that electrical stimulation of either the mesencephalic locomotor region or the gastrocnemius nerve at current intensities that recruited group III afferents inhibited the discharge of nucleus tractus solitarius cells receiving baroreceptor input. We also found that the inhibitory effects of both gastrocnemius nerve stimulation and mesencephalic locomotor region stimulation converged onto the same barosensory nucleus tractus solitarius cells. We conclude that the nucleus tractus solitarius is probably the site whereby input from both central command and thin fiber muscle afferents function to reset the baroreceptor reflex during exercise.
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Affiliation(s)
- A M Degtyarenko
- Division of Cardiovascular Medicine TB-172, One Shields Drive, University of California, Davis, Davis, CA 95616, USA.
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Perreault MC, Pastor-Bernier A, Renaud JS, Roux S, Glover JC. C fragment of tetanus toxin hybrid proteins evaluated for muscle-specific transsynaptic mapping of spinal motor circuitry in the newborn mouse. Neuroscience 2006; 141:803-816. [PMID: 16713105 DOI: 10.1016/j.neuroscience.2006.04.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/08/2006] [Accepted: 04/02/2006] [Indexed: 11/17/2022]
Abstract
We investigated whether the non-toxic C fragment of tetanus toxin (TTC) fused to either beta-galactosidase or green fluorescent protein could be utilized to transsynaptically trace muscle-specific spinal circuitry in the neonatal mouse after i.m. injection into a single hindlimb muscle. We found that even with careful low volume injection (0.2-1.0 microl) into a single muscle (medial gastrocnemius), the TTC hybrid proteins spread rapidly to many other hindlimb muscles and to trunk musculature such that retrograde labeling of motoneurons could not be constrained to a single motoneuron pool. Retrogradely labeled motoneurons in the lower lumbar segments harboring the medial gastrocnemius motoneuron pool were first observed two hours after the medial gastrocnemius injection. Within the next 10 h, additional lumbar and lower thoracic motoneurons became labeled, and punctate labeling in the neuropil surrounding the motoneurons appeared. Many of the TTC hybrid protein-labeled puncta in the neuropil co-localized synaptotagmin, indicating that they represent presynaptic axon terminals onto motoneurons. Although this is consistent with retrograde transsynaptic passage, we found no evidence that the TTC hybrid proteins were transported further along premotor axons to label interneuron somata. The i.m. TTC injection procedure described here therefore provides an important tool for the study of presynaptic terminals onto motoneurons. However, additional technical modifications will be required to utilize TTC tracers for transsynaptic mapping of muscle-specific spinal motor circuitry in the neonatal mouse. We provide here a set of criteria for assessing the i.m. delivery of TTC tracers as a basis for future improvements in this technique.
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Affiliation(s)
- M-C Perreault
- Department of Physiology, University of Oslo, Domus Medica, Sognsvannsveien 9, POB 1103 Blindern, N-0317 Oslo, Norway.
| | - A Pastor-Bernier
- Department of Physiology, University of Oslo, Domus Medica, Sognsvannsveien 9, POB 1103 Blindern, N-0317 Oslo, Norway
| | - J-S Renaud
- Department of Physiology, University of Oslo, Domus Medica, Sognsvannsveien 9, POB 1103 Blindern, N-0317 Oslo, Norway
| | - S Roux
- Unité d'Embryologie Moléculaire, Institut Pasteur, Unités de Recherche Associées 2578, Centre National de la Recherche Scientifique, 25 rue du Dr roux, 75724 Paris, France
| | - J C Glover
- Department of Physiology, University of Oslo, Domus Medica, Sognsvannsveien 9, POB 1103 Blindern, N-0317 Oslo, Norway
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Panneton WM, Gan Q, Juric R. Brainstem projections from recipient zones of the anterior ethmoidal nerve in the medullary dorsal horn. Neuroscience 2006; 141:889-906. [PMID: 16753263 DOI: 10.1016/j.neuroscience.2006.04.055] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 04/13/2006] [Accepted: 04/14/2006] [Indexed: 11/29/2022]
Abstract
Stimulation of the anterior ethmoidal nerve or the nasal mucosa induces cardiorespiratory responses similar to those seen in diving mammals. We have utilized the transganglionic transport of a cocktail of horseradish peroxidase conjugates and anterograde and retrograde tract tracing techniques to elucidate pathways which may be important for these responses in the rat. Label was seen throughout the trigeminal sensory complex after the horseradish peroxidase conjugates were applied to the anterior ethmoidal nerve peripherally. Reaction product was most dense in the medullary dorsal horn, especially in laminae I and II. Injections were made of biotinylated dextran amine into the recipient zones of the medullary dorsal horn from the anterior ethmoidal nerve, and the anterogradely transported label documented. Label was found in many brainstem areas, but fibers with varicosities were noted in specific subdivisions of the nucleus tractus solitarii and parabrachial nucleus, as well as parts of the caudal and rostral ventrolateral medulla and A5 (noradrenergic cell group in ventrolateral pons) area. The retrograde transport of FluoroGold into the medullary dorsal horn after injections into these areas showed most neurons in laminae I, II, and V. Label was especially dense in areas which received primary afferent fibers from the anterior ethmoidal nerve. These data identify potential neural circuits for the diving response of the rat.
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Affiliation(s)
- W M Panneton
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, 1402 S. Grand Boulevard, St. Louis, MO 63104-1004, USA.
| | - Q Gan
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, 1402 S. Grand Boulevard, St. Louis, MO 63104-1004, USA
| | - R Juric
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, 1402 S. Grand Boulevard, St. Louis, MO 63104-1004, USA
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Abstract
The exercise pressor reflex (a peripheral neural reflex originating in skeletal muscle) contributes significantly to the regulation of the cardiovascular system during exercise. Exercise-induced signals that comprise the afferent arm of the reflex are generated by activation of mechanically (muscle mechanoreflex) and chemically sensitive (muscle metaboreflex) skeletal muscle receptors. Activation of these receptors and their associated afferent fibres reflexively adjusts sympathetic and parasympathetic nerve activity during exercise. In heart failure, the cardiovascular response to exercise is augmented. Owing to the peripheral skeletal myopathy that develops in heart failure (e.g. muscle atrophy, decreased peripheral blood flow, fibre-type transformation and reduced oxidative capacity), the exercise pressor reflex has been implicated as a possible mechanism by which the cardiovascular response to physical activity is exaggerated in this disease. Accumulating evidence supports this conclusion. This review therefore focuses on the role of the exercise pressor reflex in regulating the cardiovascular system during exercise in both health and disease. Updates on our current understanding of the exercise pressor reflex neural pathway as well as experimental models used to study this reflex are presented. In addition, special emphasis is placed on the changes in exercise pressor reflex activity that develop in heart failure, including the contributions of the muscle mechanoreflex and metaboreflex to this pressor reflex dysfunction.
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Affiliation(s)
- Scott A Smith
- Department of Physical Therapy, Harry S. Moss Heart Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-9174 USA
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