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Masuoka T, Yamashita Y, Yoshida J, Nakano K, Tawa M, Nishio M, Ishibashi T. Sensitization of glutamate receptor-mediated pain behaviour via nerve growth factor-dependent phosphorylation of transient receptor potential V1 under inflammatory conditions. Br J Pharmacol 2020; 177:4223-4241. [PMID: 32579702 DOI: 10.1111/bph.15176] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 05/19/2020] [Accepted: 06/16/2020] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Glutamate and metabotropic glutamate (mGlu) receptors on primary sensory neurons are crucial in modulating pain sensitivity. However, it is unclear how inflammation affects mGlu receptor-mediated nociceptive responses. We therefore investigated the effects of mGlu1/5 receptor agonists on pain-related behaviour during persistent inflammation and their underlying mechanisms. EXPERIMENTAL APPROACH Effects of a mGlu1/5 receptor agonist on pain-related behaviour during inflammation was assessed in mice. Intracellular calcium responses, membrane current responses, and protein expression in primary sensory neurons were examined using cultured dorsal root ganglion (DRG) neurons, dissociated from wild-type and gene knockout mice. KEY RESULTS Persistent inflammation induced by complete Freund's adjuvant increased the duration of mGlu1/5 receptor-mediated pain behaviour, which was antagonized by inhibition of nerve growth factor (NGF)-tropomyosin receptor kinase A (TrkA) signalling. Calcium imaging revealed that NGF treatment increased the number of cultured DRG neurons responding to mGlu1/5 receptor activation. Stimulation of mGlu1/5 receptors in NGF-treated DRG neurons induced inward currents through TRPV1 channels in association with PLC but not with IP3 receptors. NGF treatment also increased the number of neurons responding to a DAG analogue via TRPV1 channel activation. Furthermore, NGF up-regulated expression of TRPV1 and A-kinase anchoring protein 5 (AKAP5), resulting in increased AKAP5-dependent TRPV1 phosphorylation. AKAP5 knockout mice did not exhibit mGlu1/5 receptor-mediated excitation in NGF-treated DRG neurons or pain response facilitation under inflammatory conditions. CONCLUSIONS AND IMPLICATIONS NGF augments glutamate- and mGlu1/5 receptor-mediated excitation of nociceptive neurons by AKAP5-dependent phosphorylation of TRPV1 channels, potentiating hypersensitivity to glutamate in inflamed tissues.
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Affiliation(s)
- Takayoshi Masuoka
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan.,Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa, Japan
| | - Yuka Yamashita
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Junko Yoshida
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Katsuya Nakano
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Masashi Tawa
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Matomo Nishio
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
| | - Takaharu Ishibashi
- Department of Pharmacology, School of Medicine, Kanazawa Medical University, Uchinada, Ishikawa, Japan
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2
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Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
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3
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Shenoy PA, Kuo A, Khan N, Gorham L, Nicholson JR, Corradini L, Vetter I, Smith MT. The Somatostatin Receptor-4 Agonist J-2156 Alleviates Mechanical Hypersensitivity in a Rat Model of Breast Cancer Induced Bone Pain. Front Pharmacol 2018; 9:495. [PMID: 29867498 PMCID: PMC5962878 DOI: 10.3389/fphar.2018.00495] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 04/25/2018] [Indexed: 12/12/2022] Open
Abstract
In the majority of patients with breast cancer in the advanced stages, skeletal metastases are common, which may cause excruciating pain. Currently available drug treatments for relief of breast cancer-induced bone pain (BCIBP) include non-steroidal anti-inflammatory drugs and strong opioid analgesics along with inhibitors of osteoclast activity such as bisphosphonates and monoclonal antibodies such as denosumab. However, these medications often lack efficacy and/or they may produce serious dose-limiting side effects. In the present study, we show that J-2156, a somatostatin receptor type 4 (SST4 receptor) selective agonist, reverses pain-like behaviors in a rat model of BCIBP induced by unilateral intra-tibial injection of Walker 256 breast cancer cells. Following intraperitoneal administration, the ED50 of J-2156 for the relief of mechanical allodynia and mechanical hyperalgesia in the ipsilateral hindpaws was 3.7 and 8.0 mg/kg, respectively. Importantly, the vast majority of somatosensory neurons in the dorsal root ganglia including small diameter C-fibers and medium-large diameter fibers, that play a crucial role in cancer pain hypersensitivities, expressed the SST4 receptor. J-2156 mediated pain relief in BCIBP-rats was confirmed by observations of a reduction in the levels of phosphorylated extracellular signal-regulated kinase (pERK), a protein essential for central sensitization and persistent pain, in the spinal dorsal horn. Our results demonstrate the potential of the SST4 receptor as a pharmacological target for relief of BCIBP and we anticipate the present work to be a starting point for further mechanism-based studies.
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Affiliation(s)
- Priyank A Shenoy
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Andy Kuo
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Nemat Khan
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Louise Gorham
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany
| | - Janet R Nicholson
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany
| | - Laura Corradini
- Department of CNS Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.,Faculty of Health and Behavioural Sciences, School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
| | - Maree T Smith
- Faculty of Medicine, School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia.,Faculty of Health and Behavioural Sciences, School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia
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Li JH, He PY, Fan DN, Alemujiang D, Huo FQ, Zhao Y, Cao DY. Peripheral ionotropic glutamate receptors contribute to Fos expression increase in the spinal cord through antidromic electrical stimulation of sensory nerves. Neurosci Lett 2018; 678:1-7. [PMID: 29705538 DOI: 10.1016/j.neulet.2018.04.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/24/2018] [Accepted: 04/25/2018] [Indexed: 10/17/2022]
Abstract
Previous studies have shown that peripheral ionotropic glutamate receptors are involved in the increase in sensitivity of a cutaneous branch of spinal dorsal ramus (CBDR) through antidromic electrical stimulation (ADES) of another CBDR in the adjacent segment. CBDR in the thoracic segments run parallel to each other and no synaptic contact at the periphery is reported. The present study investigated whether the increased sensitivity of peripheral sensory nerves via ADES of a CBDR induced Fos expression changes in the adjacent segments of the spinal cord. Fos expression increased in the T8 - T12 segments of the spinal cord evoked by ADES of the T10 CBDR in rats. The increased Fos expression in the T11 and T12, but not T8 - T10 spinal cord segments, was significantly blocked by local application of either N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine maleate (MK-801) or non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (DNQX) into the receptive field of T11 CBDR. The results suggest that endogenous glutamate released by ADES of sensory nerve may bind to peripheral ionotropic glutamate receptors and activate adjacent sensory nerve endings to increase the sensitivity of the spinal cord. These data reveal the potential mechanisms of neuron activation in the spinal cord evoked by peripheral sensitization.
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Affiliation(s)
- Jia-Heng Li
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, 98 West 5th Road, Xi'an, Shaanxi 710004, P. R. China
| | - Pei-Yao He
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, 98 West 5th Road, Xi'an, Shaanxi 710004, P. R. China
| | - Dan-Ni Fan
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, 98 West 5th Road, Xi'an, Shaanxi 710004, P. R. China
| | - Dilinapa Alemujiang
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, 98 West 5th Road, Xi'an, Shaanxi 710004, P. R. China
| | - Fu-Quan Huo
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an, Shaanxi 710061, P. R. China
| | - Yan Zhao
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University Health Science Center, 76 West Yanta Road, Xi'an, Shaanxi 710061, P. R. China
| | - Dong-Yuan Cao
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, 98 West 5th Road, Xi'an, Shaanxi 710004, P. R. China.
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Pethő G, Bölcskei K, Füredi R, Botz B, Bagoly T, Pintér E, Szolcsányi J. Evidence for a novel, neurohumoral antinociceptive mechanism mediated by peripheral capsaicin-sensitive nociceptors in conscious rats. Neuropeptides 2017; 62:1-10. [PMID: 28291541 DOI: 10.1016/j.npep.2017.02.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 12/16/2016] [Accepted: 02/07/2017] [Indexed: 11/20/2022]
Abstract
Stimulation of capsaicin-sensitive peripheral sensory nerve terminals induces remote anti-inflammatory effects throughout the body of anesthetized rats and guinea-pigs mediated by somatostatin. As somatostatin has also antinociceptive effects, the study aimed at investigating whether similar remote antinociceptive effects can be demonstrated in awake animals. In conscious rats, nociceptive nerve endings of the right hind paw decentralized by cutting the sciatic and saphenous nerves 18h before were chemically stimulated, and drop of the noxious heat threshold (heat hyperalgesia) induced by prior (18h before) plantar incision was measured on the contralateral, left hind paw using an increasing-temperature water bath. 18h after nerve transection, mustard oil-evoked plasma extravasation was not significantly reduced in the right hind paw as tested by in vivo fluorescence imaging. Applying agonist of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptor (capsaicin or mustard oil, respectively) to the nerve-transected paw inhibited the plantar incision-induced drop of the noxious heat threshold on the contralateral paw. The onset of these remote antihyperalgesic effects was 10-20min. A similar contralateral inhibitory effect of capsaicin or mustard oil treatment was observed on neuropathic mechanical hyperalgesia evoked by partial sciatic nerve injury 2days before nerve transection and measured by a Randall-Selitto apparatus. The remote thermal antihyperalgesic effect was prevented by chronic (5days) denervation or local capsaicin desensitization of the stimulated paw; reduced by intraperitoneally applied antagonist of somatostatin (cyclosomatostatin) or opioid receptors (naloxone). The response was mimicked by intraperitoneally applied somatostatin and associated with a 72±27% increase in plasma somatostatin-like immunoreactivity that was absent after chronic (5days) denervation. In conclusion, chemical activation of decentralized peripheral capsaicin-sensitive nociceptors evokes remote antihyperalgesic responses initiated outside the central nervous system and mediated by somatostatin and endogenous opioids.
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Affiliation(s)
- Gábor Pethő
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary.
| | - Kata Bölcskei
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary; Molecular Pharmacology Research Team, János Szentágothai Research Centre, University of Pécs, Ifjúság útja 20, H-7624 Pécs, Hungary
| | - Réka Füredi
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - Bálint Botz
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary; Molecular Pharmacology Research Team, János Szentágothai Research Centre, University of Pécs, Ifjúság útja 20, H-7624 Pécs, Hungary
| | - Teréz Bagoly
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - Erika Pintér
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
| | - János Szolcsányi
- Department of Pharmacology and Pharmacotherapy, University of Pécs, Szigeti út 12, H-7624 Pécs, Hungary
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6
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Guo Y, Cao DY, Zhang ZJ, Yao FR, Wang HS, Zhao Y. Electrical signal propagated across acupoints along Foot Taiyang Bladder Meridian in rats. Chin J Integr Med 2015; 22:537-44. [PMID: 26631142 DOI: 10.1007/s11655-015-2300-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate the electrical signals propagated along Foot Taiyang Bladder Meridian (BL) in a rat model. METHODS The experiments were performed on Dark-Agouti (DA), DA.1U and Sprague Dawley (SD) rats. The antidromic electrical stimulation was applied on the nerve innervating "Pishu" (BL 20) to mimic the acupoint electro-acupuncture (EA). The activities recording from adjacent nerve innervating acupoint "Danshu" (BL 19) or "Weishu" (BL 21) were recorded as indics for acupoint, including the mechanical threshold and discharge rate. RESULTS After mimic EA on BL 20, C and Aδ units from adjacent BL 19 or BL 21 were sensitized including the decrease in mechanical threshold and increase in discharge rates in DA, DA.1U and SD rats, especially in DA rats. The average discharge rate increased from 2.40±0.26 to 6.06±0.55 and from 1.92±0.42 to 6.17±1.10 impulse/min (P<0.01), and the mechanical threshold decreased from 0.52±0.12 to 0.24±0.05 and from 0.27±0.02 to 0.16±0.01 mmol/L (P<0.01) in C (n=15) and Aδ (n=18) units in DA rats. The net change in discharge rates from C units were 152.5%, 144.7% and 42.4% in DA, DA.1U and SD rats, respectively, among which DA rat's was the highest (P<0.05). In Aδ units, the net change in DA rats were also the highest (221.5%, 139.2% and 49.2% in DA, DA.1U and SD rats). CONCLUSIONS These results showed that mimic acupoint EA activated adjacent acupoints along BL in three rat strains, which might be related to propagated sensation along meridians (PSM). In addition, DA rats were more sensitive and might be a good model animal for PSM research.
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Affiliation(s)
- Yuan Guo
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Dong-Yuan Cao
- Research Center for Stomatology, Stomatological Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, 710004, China
| | - Zhang-Jin Zhang
- School of Chinese Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Fan-Rong Yao
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Hui-Sheng Wang
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Yan Zhao
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China.
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7
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Guo Y, Yao FR, Cao DY, Li L, Wang HS, Xie W, Zhao Y. The major histocompatibility complex genes impact pain response in DA and DA.1U rats. Physiol Behav 2015; 147:30-7. [PMID: 25861730 DOI: 10.1016/j.physbeh.2015.04.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 03/13/2015] [Accepted: 04/04/2015] [Indexed: 12/29/2022]
Abstract
Our recent studies have shown that the difference in basal pain sensitivity to mechanical and thermal stimulation between Dark-Agouti (DA) rats and a novel congenic DA.1U rats is major histocompatibility complex (MHC) genes dependent. In the present study, we further used DA and DA.1U rats to investigate the role of MHC genes in formalin-induced pain model by behavioral, electrophysiological and immunohistochemical methods. Behavioral results showed biphasic nociceptive behaviors increased significantly following the intraplantar injection of formalin in the hindpaw of DA and DA.1U rats. The main nociceptive behaviors were lifting and licking, especially in DA rats (P<0.001 and P<0.01). The composite pain scores (CPS) in DA rats were significantly higher than those in DA.1U rats in both phases of the formalin test (P<0.01). Electrophysiological results also showed the biphasic increase in discharge rates of C and Aδ fibers of L5 dorsal root in the two strains, and the net change of the discharge rate of DA rats was significantly higher than that of DA.1U rats (P<0.05). The mechanical thresholds decreased after formalin injection in both strains (P<0.01), and the net change in the mechanical threshold in DA was greater than that in DA.1U rats (P<0.05). The expression of RT1-B, representation of MHC class II molecule, in laminae I-II of L4/5 spinal cord in DA rats was significantly higher than that in DA.1U rats in the respective experimental group (P<0.05). These results suggested that both DA and DA.1U rats exhibited nociceptive responses in formalin-induced pain model and DA rats were more sensitive to noxious chemical stimulus than DA.1U rats, indicating that MHC genes might contribute to the difference in pain sensitivity.
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Affiliation(s)
- Yuan Guo
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China
| | - Fan-Rong Yao
- Department of Pharmacology and Toxicology in the Brody School of Medicine at East Carolina University, Greenville, NC, USA
| | - Dong-Yuan Cao
- Research Center, Stomatological Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710004, PR China; Department of Neural and Pain Sciences, University of Maryland Dental School, 650 West, Baltimore Street, Baltimore, MD 21201, USA
| | - Li Li
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China
| | - Hui-Sheng Wang
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China
| | - Wen Xie
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China
| | - Yan Zhao
- Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China.
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On the g-protein-coupled receptor heteromers and their allosteric receptor-receptor interactions in the central nervous system: focus on their role in pain modulation. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:563716. [PMID: 23956775 PMCID: PMC3730365 DOI: 10.1155/2013/563716] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/20/2013] [Accepted: 05/24/2013] [Indexed: 12/16/2022]
Abstract
The modulatory role of allosteric receptor-receptor interactions in the pain pathways of the Central Nervous System and the peripheral nociceptors has become of increasing interest. As integrators of nociceptive and antinociceptive wiring and volume transmission signals, with a major role for the opioid receptor heteromers, they likely have an important role in the pain circuits and may be involved in acupuncture. The delta opioid receptor (DOR) exerts an antagonistic allosteric influence on the mu opioid receptor (MOR) function in a MOR-DOR heteromer. This heteromer contributes to morphine-induced tolerance and dependence, since it becomes abundant and develops a reduced G-protein-coupling with reduced signaling mainly operating via β-arrestin2 upon chronic morphine treatment. A DOR antagonist causes a return of the Gi/o binding and coupling to the heteromer and the biological actions of morphine. The gender- and ovarian steroid-dependent recruitment of spinal cord MOR/kappa opioid receptor (KOR) heterodimers enhances antinociceptive functions and if impaired could contribute to chronic pain states in women. MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, mediating morphine induced itch. Other mechanism for the antinociceptive actions of acupuncture along meridians may be that it enhances the cross-desensitization of the TRPA1 (chemical nociceptor)-TRPV1 (capsaicin receptor) heteromeric channel complexes within the nociceptor terminals located along these meridians. Selective ionotropic cannabinoids may also produce cross-desensitization of the TRPA1-TRPV1 heteromeric nociceptor channels by being negative allosteric modulators of these channels leading to antinociception and antihyperalgesia.
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Zhang WB, Zhao Y, Kjell F. Understanding propagated sensation along meridians by volume transmission in peripheral tissue. Chin J Integr Med 2013; 19:330-9. [PMID: 23674110 DOI: 10.1007/s11655-013-1456-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Indexed: 02/03/2023]
Abstract
Propagated sensation along meridians (PSM) is a phenomenon that a sensation moves along meridians during stimulation of an acupoint. PSM has an appearance rate of 1.3% among people and have characteristics of low speed, going toward afflicted sites and being blocked by physical pressure which is difficult to be explained by known neural and blood transmission. Volume transmission (VT) is a widespread mode of intercellular communication in the central nervous system that occurs in the extracellular fluid and in the cerebrospinal fluid. VT signals moves from source to target cells via energy gradients leading to diffusion and convection (flow) which is slow, long distance and much less space filling. VT channel diffuse forming a plexus in the extracellular space with two parameters of volume fraction and tortuosity. Some experiments showed an information transmission between adjacent and distant acupoints along meridians cross spinal segments. This process is a cross-excitation between peripheral nerve terminals which is related to nonsynaptic transmission. Some neurotransmitters or neuropeptides such as glutamate, adenosine triphosphate (ATP) and neuropeptide such as substance P, neurokinin A and calcitonin gene-related peptide relate with the cross-excitation which can be regards as VT signals. Comparing the characteristics of PSM and VT, many similar aspects can be found leading to an assumption that PSM is a process of VT in peripheral tissue along meridians. The reason why VT signals transmit along meridians is that the meridian is rich in interstitial fluid under the condition of low hydraulic resistance which has been proven experimentally. According to Darcy's law which descript the flow of interstitial fluid and conservation equation, interstitial fluid will move toward meridians and flow along meridians that restrict the VT signals within the channel and accelerate the flow according to Fick's diffusion law. During the process, a degranulation of histamine from mast cells happens on the route which can expand capillary and increase the blood perfusion and interstitial fluid which had already been observed. The mechanism of PSM is featured by alternative axon reflex (wired transmission, WT) and VT in peripheral tissue along meridians, sending simultaneously a continuous sensate signal to control nerve system which can be felt like a PSM.
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Affiliation(s)
- Wei-Bo Zhang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Science, Beijing 100700, China.
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10
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Neural acupuncture unit: a new concept for interpreting effects and mechanisms of acupuncture. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:429412. [PMID: 22474503 PMCID: PMC3310280 DOI: 10.1155/2012/429412] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Revised: 11/30/2011] [Accepted: 12/01/2011] [Indexed: 12/12/2022]
Abstract
When an acupuncture needle is inserted into a designated point on the body and
mechanical or electrical stimulation is delivered, various neural and neuroactive
components are activated. The collection of the activated neural and neuroactive
components distributed in the skin, muscle, and connective tissues surrounding the
inserted needle is defined as a neural acupuncture unit (NAU). The traditionally defined
acupoints represent an anatomical landmark system that indicates local sites where NAUs
may contain relatively dense and concentrated neural and neuroactive components, upon
which acupuncture stimulation would elicit a more efficient therapeutic response. The
NAU-based local mechanisms of biochemical and biophysical reactions play an important
role in acupuncture-induced analgesia. Different properties of NAUs are associated with
different components of needling sensation. There exist several central pathways to
convey NAU-induced acupuncture signals, Electroacupuncture (EA) frequency-specific
neurochemical effects are related to different peripheral and central pathways transmitting
afferent signals from different frequency of NAU stimulation. More widespread and intense
neuroimaging responses of brain regions to acupuncture may be a consequence of more
efficient NAU stimulation modes. The introduction of the conception of NAU provides a
new theoretical approach to interpreting effects and mechanisms of acupuncture in
modern biomedical knowledge framework.
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Wang J, Cao DY, Guo Y, Ma SJ, Luo R, Pickar JG, Zhao Y. Octreotide inhibits capsaicin-induced activation of C and Aδ afferent fibres in rat hairy skin in vivo. Clin Exp Pharmacol Physiol 2012; 38:521-7. [PMID: 21595740 DOI: 10.1111/j.1440-1681.2011.05542.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
1. The present study investigated whether the somatostatin receptor (SSTR) agonist, octreotide, could inhibit the activation of dorsal skin afferent fibres induced by local injection of capsaicin in the rat. 2. Single unit activity from Aδ mechano-heat sensitive (AMH; n = 41) and C mechano-heat sensitive (CMH; n = 30) afferents was recorded after their isolation in thin filaments from the dorsal cutaneous nerve branches. The effect of subcutaneous octreotide injection on the change in discharge rate and mechanical threshold induced by capsaicin was determined. 3. Capsaicin (0.05%) injection into the edge of the receptive field of both AMH and CMH units increased their discharge rate and decreased their mechanical threshold. Pre-injection of octreotide inhibited these responses, and co-application of SSTR antagonist, cyclosomatostatin, reversed the inhibitory effect of octreotide. 4. The present study provides electrophysiological evidence that the signal evoked by the somatostatin receptor inhibits the activation and mechanical sensitization evoked by capsaicin in the terminals in small-diameter sensory neurons.
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Affiliation(s)
- Jun Wang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Shaanxi, China
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Luo R, Guo Y, Cao DY, Pickar JG, Li L, Wang J, Zhao Y. Local effects of octreotide on glutamate-evoked activation of Aδ and C afferent fibers in rat hairy skin. Brain Res 2010; 1322:50-8. [DOI: 10.1016/j.brainres.2010.01.058] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 01/19/2010] [Accepted: 01/22/2010] [Indexed: 10/19/2022]
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Tonic inhibition of somatostatin on C and Aδ afferent fibers in rat dorsal skin in vivo. Brain Res 2009; 1288:50-9. [DOI: 10.1016/j.brainres.2009.06.088] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 06/11/2009] [Accepted: 06/30/2009] [Indexed: 11/18/2022]
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