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Islam J, Rahman MT, Kc E, Park YS. Deciphering the functional role of insular cortex stratification in trigeminal neuropathic pain. J Headache Pain 2024; 25:76. [PMID: 38730344 PMCID: PMC11084050 DOI: 10.1186/s10194-024-01784-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 05/06/2024] [Indexed: 05/12/2024] Open
Abstract
Trigeminal neuropathic pain (TNP) is a major concern in both dentistry and medicine. The progression from normal to chronic TNP through activation of the insular cortex (IC) is thought to involve several neuroplastic changes in multiple brain regions, resulting in distorted pain perception and associated comorbidities. While the functional changes in the insula are recognized contributors to TNP, the intricate mechanisms underlying the involvement of the insula in TNP processing remain subjects of ongoing investigation. Here, we have overviewed the most recent advancements regarding the functional role of IC in regulating TNP alongside insights into the IC's connectivity with other brain regions implicated in trigeminal pain pathways. In addition, the review examines diverse modulation strategies that target the different parts of the IC, thereby suggesting novel diagnostic and therapeutic management of chronic TNP in the future.
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Affiliation(s)
- Jaisan Islam
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Md Taufiqur Rahman
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Elina Kc
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Korea
- Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Young Seok Park
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Korea.
- Department of Neurosurgery, Chungbuk National University Hospital, Cheongju, Korea.
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Kim K, Nan G, Bak H, Kim HY, Kim J, Cha M, Lee BH. Insular cortex stimulation alleviates neuropathic pain through changes in the expression of collapsin response mediator protein 2 involved in synaptic plasticity. Neurobiol Dis 2024; 194:106466. [PMID: 38471625 DOI: 10.1016/j.nbd.2024.106466] [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: 01/12/2024] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
In recent studies, brain stimulation has shown promising potential to alleviate chronic pain. Although studies have shown that stimulation of pain-related brain regions can induce pain-relieving effects, few studies have elucidated the mechanisms of brain stimulation in the insular cortex (IC). The present study was conducted to explore the changes in characteristic molecules involved in pain modulation mechanisms and to identify the changes in synaptic plasticity after IC stimulation (ICS). Following ICS, pain-relieving behaviors and changes in proteomics were explored. Neuronal activity in the IC after ICS was observed by optical imaging. Western blotting was used to validate the proteomics data and identify the changes in the expression of glutamatergic receptors associated with synaptic plasticity. Experimental results showed that ICS effectively relieved mechanical allodynia, and proteomics identified specific changes in collapsin response mediator protein 2 (CRMP2). Neuronal activity in the neuropathic rats was significantly decreased after ICS. Neuropathic rats showed increased expression levels of phosphorylated CRMP2, alpha amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR), and N-methyl-d-aspartate receptor (NMDAR) subunit 2B (NR2B), which were inhibited by ICS. These results indicate that ICS regulates the synaptic plasticity of ICS through pCRMP2, together with AMPAR and NR2B, to induce pain relief.
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Affiliation(s)
- Kyeongmin Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Guanghai Nan
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hyeji Bak
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hee Young Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Junesun Kim
- Rehabilitation Science Program, Department of Health Science, Graduate School, Korea University, Seoul 02841, Republic of Korea; Department of Health and Environment Science, College of Health Science, Korea University, Seoul 02841, Republic of Korea
| | - Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea.
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul 03722, Republic of Korea.
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Islam J, Kc E, Kim S, Chung MY, Park KS, Kim HK, Park YS. Optogenetic Inhibition of Glutamatergic Neurons in the Dysgranular Posterior Insular Cortex Modulates Trigeminal Neuropathic Pain in CCI-ION Rat. Neuromolecular Med 2023; 25:516-532. [PMID: 37700212 DOI: 10.1007/s12017-023-08752-3] [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: 06/02/2023] [Accepted: 08/15/2023] [Indexed: 09/14/2023]
Abstract
In individuals with chronic neuropathic pain, the posterior insular cortex (PIC) has been found to exhibit increased glutamatergic activity, and the dysgranular portion of PIC (DPIC) has been investigated as a novel cortical target for pain modulation. However, the role of DPIC glutamatergic neurons (DPICg) in trigeminal neuropathic pain (TNP) remains unclear. Here, we examined the outcomes of DPICg inhibition in a rat model of chronic constriction injury of the infraorbital nerve (CCI-ION). Animals were randomly divided into TNP, sham, and control groups. TNP animals underwent CCI-ION surgery. Either optogenetic or null viruses were delivered to the contralateral DPICg of TNP and sham animals. In vivo single-unit extracellular recordings from the ipsilateral spinal trigeminal nucleus caudalis (TNC) and contralateral ventral posteromedial (VPM) thalamus were obtained under both "ON" and "OFF" stimulation states. Behavioral responses during the stimulation-OFF and stimulation-ON phases were examined. Expression of c-Fos, pERK, and CREB immunopositive neurons were also observed. Optogenetic inhibition of contralateral DPICg decreased the neural firing rate in both TNC and VPM thalamus, the expression of sensory-responsive cell bodies, and transcriptional factors in the DPIC of TNP group. Improvements in hyperalgesia, allodynia, and anxiety-like responses in TNP animals were also observed during stimulation-ON condition. In fine, descending pain processing is influenced by neuroanatomical projections from the DPIC to the pain matrix areas, and DPICg could play a necessary role in this neural circuitry. Therefore, the antinociceptive effect of DPICg inhibition in this study may provide evidence for the therapeutic potential of DPICg in TNP.
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Affiliation(s)
- Jaisan Islam
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Chungbuk, Korea
| | - Elina Kc
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Chungbuk, Korea
| | - Soochong Kim
- Department of Veterinary Medicine, College of Veterinary Medicine, Chungbuk National University, Cheongju, Korea
| | - Moon Young Chung
- Department of Neurosurgery, Soonchunhyang University, Bucheon, Korea
| | - Ki Seok Park
- Department of Neurosurgery, Eulji University Hospital, Daejeon, Korea
| | - Hyong Kyu Kim
- Department of Medicine and Microbiology, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Young Seok Park
- Department of Medical Neuroscience, College of Medicine, Chungbuk National University, Cheongju, Chungbuk, Korea.
- Department of Neurosurgery, Chungbuk National University Hospital, 776, 1 Sunhwanro, Seowon-gu, Cheongju, 28644, Korea.
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Przybylowicz PK, Sokolowska KE, Rola H, Wojdacz TK. DNA Methylation Changes in Blood Cells of Fibromyalgia and Chronic Fatigue Syndrome Patients. J Pain Res 2023; 16:4025-4036. [PMID: 38054109 PMCID: PMC10695140 DOI: 10.2147/jpr.s439412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/13/2023] [Indexed: 12/07/2023] Open
Abstract
Purpose Fibromyalgia (FM) and Chronic Fatigue Syndrome (CFS) affect 0.4% and 1% of society, respectively, and the prevalence of these pain syndromes is increasing. To date, no strong association between these syndromes and the genetic background of affected individuals has been shown. Therefore, it is plausible that epigenetic changes might play a role in the development of these syndromes. Patients and Methods Three previous studies have attempted to elaborate the involvement of genome-wide methylation changes in blood cells in the development of fibromyalgia and chronic fatigue syndrome. These studies included 22 patients with fibromyalgia and 127 patients with CFS, and the results of the studies were largely discrepant. Contradicting results of those studies may be attributed to differences in the omics data analysis approaches used in each study. We reanalyzed the data collected in these studies using an updated and coherent data-analysis framework. Results Overall, the methylation changes that we observed overlapped with previous results only to some extent. However, the gene set enrichment analyses based on genes annotated to methylation changes identified in each of the analyzed datasets were surprisingly coherent and uniformly associated with the physiological processes that, when affected, may result in symptoms characteristic of fibromyalgia and chronic fatigue syndrome. Conclusion Methylomes of the blood cells of patients with FM and CFS in three independent studies have shown methylation changes that appear to be implicated in the pathogenesis of these syndromes.
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Affiliation(s)
| | | | - Hubert Rola
- Independent Clinical Epigenetics Laboratory, Pomeranian Medical University, Szczecin, Poland
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Neurocircuit of chronic pain and pain-induced negative emotions and regulatory mechanisms of electroacupuncture. WORLD JOURNAL OF ACUPUNCTURE-MOXIBUSTION 2022. [DOI: 10.1016/j.wjam.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
N-methyl-d-aspartate receptors (NMDARs) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) are excitatory neurotransmission receptors of the central nervous system and play vital roles in synaptic plasticity. Although not fully elucidated, visceral hypersensitivity is one of the most well-characterized pathophysiologic abnormalities of functional gastrointestinal diseases and appears to be associated with increased synaptic plasticity. In this study, we review the updated findings on the physiology of NMDARs and AMPARs and their relation to visceral hypersensitivity, which propose directions for future research in this field with evolving importance.
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Choi S, Kim K, Kwon M, Bai SJ, Cha M, Lee BH. Modulation of Neuropathic Pain by Glial Regulation in the Insular Cortex of Rats. Front Mol Neurosci 2022; 15:815945. [PMID: 35493331 PMCID: PMC9043281 DOI: 10.3389/fnmol.2022.815945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/22/2022] [Indexed: 12/12/2022] Open
Abstract
The insular cortex (IC) is known to process pain information. However, analgesic effects of glial inhibition in the IC have not yet been explored. The aim of this study was to investigate pain alleviation effects after neuroglia inhibition in the IC during the early or late phase of pain development. The effects of glial inhibitors in early or late phase inhibition in neuropathic pain were characterized in astrocytes and microglia expressions in the IC of an animal model of neuropathic pain. Changes in withdrawal responses during different stages of inhibition were compared, and morphological changes in glial cells with purinergic receptor expressions were analyzed. Inhibition of glial cells had an analgesic effect that persisted even after drug withdrawal. Both GFAP and CD11b/c expressions were decreased after injection of glial inhibitors. Morphological alterations of astrocytes and microglia were observed with expression changes of purinergic receptors. These findings indicate that inhibition of neuroglia activity in the IC alleviates chronic pain, and that purinergic receptors in glial cells are closely related to chronic pain development.
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Affiliation(s)
- Songyeon Choi
- Department of Physiology, Yonsei University College of Medicine, Seoul, South Korea
- Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, South Korea
| | - Kyeongmin Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul, South Korea
- Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, South Korea
| | - Minjee Kwon
- Department of Nursing, Kyungil University, Gyeongsan, South Korea
| | - Sun Joon Bai
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, Seoul, South Korea
- *Correspondence: Myeounghoon Cha,
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, Seoul, South Korea
- Department of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, South Korea
- Bae Hwan Lee,
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Current Understanding of the Involvement of the Insular Cortex in Neuropathic Pain: A Narrative Review. Int J Mol Sci 2021; 22:ijms22052648. [PMID: 33808020 PMCID: PMC7961886 DOI: 10.3390/ijms22052648] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 12/22/2022] Open
Abstract
Neuropathic pain is difficult to cure and is often accompanied by emotional and psychological changes. Exploring the mechanisms underlying neuropathic pain will help to identify a better treatment for this condition. The insular cortex is an important information integration center. Numerous imaging studies have documented increased activity of the insular cortex in the presence of neuropathic pain; however, the specific role of this region remains controversial. Early studies suggested that the insular lobe is mainly involved in the processing of the emotional motivation dimension of pain. However, increasing evidence suggests that the role of the insular cortex is more complex and may even be related to the neural plasticity, cognitive evaluation, and psychosocial aspects of neuropathic pain. These effects contribute not only to the development of neuropathic pain, but also to its comorbidity with neuropsychiatric diseases. In this review, we summarize the changes that occur in the insular cortex in the presence of neuropathic pain and analgesia, as well as the molecular mechanisms that may underlie these conditions. We also discuss potential sex-based differences in these processes. Further exploration of the involvement of the insular lobe will contribute to the development of new pharmacotherapy and psychotherapy treatments for neuropathic pain.
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Tøttrup L, Diaz-Valencia G, Kamavuako EN, Jensen W. Modulation of SI and ACC response to noxious and non-noxious electrical stimuli after the spared nerve injury model of neuropathic pain. Eur J Pain 2020; 25:612-623. [PMID: 33166003 DOI: 10.1002/ejp.1697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/14/2020] [Indexed: 11/07/2022]
Abstract
BACKGROUND The current knowledge on the role of SI and ACC in acute pain processing and how these contribute to the development of chronic pain is limited. Our objective was to investigate differences in and modulation of intracortical responses from SI and ACC in response to different intensities of peripheral presumed noxious and non-noxious stimuli in the acute time frame of a peripheral nerve injury in rats. METHODS We applied non-noxious and noxious electrical stimulation pulses through a cuff electrode placed around the sciatic nerve and measured the cortical responses (six electrodes in each cortical area) before and after the spared nerve injury model. RESULTS We found that the peak response correlated with the stimulation intensity and that SI and ACC differed in both amplitude and latency of cortical response. The cortical response to both noxious and non-noxious stimulation showed a trend towards faster processing of non-noxious stimuli in ACC and increased cortical processing of non-noxious stimuli in SI after SNI. CONCLUSIONS We found different responses in SI and ACC to different intensity electrical stimulations based on two features and changes in these features following peripheral nerve injury. We believe that these features may be able to assist to track cortical changes during the chronification of pain in future animal studies. SIGNIFICANCE This study showed distinct cortical processing of noxious and non-noxious peripheral stimuli in SI and ACC. The processing latency in ACC and accumulated spiking activity in SI appeared to be modulated by peripheral nerve injury, which elaborated on the function of these two areas in the processing of nociception.
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Affiliation(s)
- Lea Tøttrup
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Gabriela Diaz-Valencia
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Ernest N Kamavuako
- Department of Engineering, King's College London, London, UK.,Faculté de Médecine, Université de Kindu, Maniema, D.R Congo
| | - Winnie Jensen
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Li XH, Chen QY, Zhuo M. Neuronal Adenylyl Cyclase Targeting Central Plasticity for the Treatment of Chronic Pain. Neurotherapeutics 2020; 17:861-873. [PMID: 32935298 PMCID: PMC7609634 DOI: 10.1007/s13311-020-00927-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2020] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is a major health problem and the effective treatment for chronic pain is still lacking. The recent crisis created by the overuse of opioids for pain treatment has clearly shown the need for non-addictive novel pain medicine. Conventional pain medicines usually inhibit peripheral nociceptive transmission and reduce central transmission, especially pain-related excitatory transmission. For example, both opioids and gabapentin produce analgesic effects by inhibiting the release of excitatory transmitters and reducing neuronal excitability. Here, we will review recent studies of central synaptic plasticity contributing to central sensitization in chronic pain. Neuronal selective adenylyl cyclase subtype 1 (AC1) is proposed to be a key intracellular protein that causes both presynaptic and postsynaptic forms of long-term potentiation (LTP). Inhibiting the activity of AC1 by selective inhibitor NB001 blocks behavioral sensitization and injury-related anxiety in animal models of chronic pain. We propose that inhibiting injury-related LTPs will provide new mechanisms for designing novel medicines for the treatment of chronic pain and its related emotional disorders.
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Affiliation(s)
- Xu-Hui Li
- Institute of Brain Research, Qingdao International Academician Park, Qingdao, Shandong China
- Center for Neuron and Disease, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi China
- Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King’s College Circle, Toronto, Ontario M5S 1A8 Canada
| | - Qi-Yu Chen
- Institute of Brain Research, Qingdao International Academician Park, Qingdao, Shandong China
- Center for Neuron and Disease, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi China
| | - Min Zhuo
- Institute of Brain Research, Qingdao International Academician Park, Qingdao, Shandong China
- Center for Neuron and Disease, Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, 710049 Shaanxi China
- Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King’s College Circle, Toronto, Ontario M5S 1A8 Canada
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Kim K, Choi S, Cha M, Lee BH. Effects of mTOR inhibitors on neuropathic pain revealed by optical imaging of the insular cortex in rats. Brain Res 2020; 1733:146720. [PMID: 32061737 DOI: 10.1016/j.brainres.2020.146720] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 01/22/2020] [Accepted: 02/07/2020] [Indexed: 11/24/2022]
Abstract
In the pain matrix, the insular cortex (IC) is mainly involved in discriminative sensory and motivative emotion. Abnormal signal transmission from injury site causes neuropathic pain, which generates enhanced synaptic plasticity. The mammalian target of rapamycin (mTOR) complex is the key regulator of protein synthesis; it is involved in the modulation of synaptic plasticity. To date, there has been no report on the changes in optical signals in the IC under neuropathic condition after treatment with mTOR inhibitors, such as Torin1 and XL388. Therefore, we aimed to determine the pain-relieving effect of mTOR inhibitors (Torin1 and XL388) and observe the changes in optical signals in the IC after treatment. Mechanical threshold was measured in adult male Sprague-Dawley rats after neuropathic surgery, and therapeutic effect of inhibitors was assessed on post-operative day 7 following the microinjection of Torin1 or XL388 into the IC. Optical signals were acquired to observe the neuronal activity of the IC in response to peripheral stimulation before and after treatment with mTOR inhibitors. Consequently, the inhibitors showed the most effective alleviation 4 h after microinjection into the IC. In optical imaging, peak amplitudes of optical signals and areas of activated regions were reduced after treatment with Torin1 and XL388. However, there were no significant optical signal changes in the IC before and after vehicle application. These findings suggested that Torin1 and XL388 are associated with the alleviation of neuronal activity that is excessively manifested in the IC, and is assumed to diminish synaptic plasticity.
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Affiliation(s)
- Kyeongmin Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Songyeon Choi
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 03722, Republic of Korea.
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Choi S, Kim K, Cha M, Kim M, Lee BH. mTOR signaling intervention by Torin1 and XL388 in the insular cortex alleviates neuropathic pain. Neurosci Lett 2020; 718:134742. [PMID: 31917234 DOI: 10.1016/j.neulet.2020.134742] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/19/2019] [Accepted: 01/03/2020] [Indexed: 12/27/2022]
Abstract
Signaling by mammalian target of rapamycin (mTOR), a kinase regulator of protein synthesis, has been implicated in the development of chronic pain. The mTOR comprises two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Although effective inhibitors of mTORC1 and C2 have been developed, studies on the effect of these inhibitors related to pain modulation are still lacking. This study was conducted to determine the inhibitory effects of Torin1 and XL388 in an animal model of neuropathic pain. Seven days after neuropathic surgery, Torin1 or XL388 were microinjected into the insular cortex (IC) of nerve-injured animals and behavioral changes were assessed. Administration of Torin1 or XL388 into the IC significantly increased mechanical thresholds and reduced mechanical allodynia. At the immunoblotting results, Torin1 and XL388 significantly reduced phosphorylation of mTOR, 4E-BP1, p70S6K, and PKCα, without affecting Akt. These results strongly suggest that Torin1 and XL388 may attenuate neuropathic pain via inhibition of mTORC1 and mTORC2 in the IC.
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Affiliation(s)
- Songyeon Choi
- Department of Physiology, Yonsei University College of Medicine, Seoul, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Kyeongmin Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Minjee Kim
- Department of Physiology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of Medicine, Seoul, Republic of Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea.
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Bai Y, Ma LT, Chen YB, Ren D, Chen YB, Li YQ, Sun HK, Qiu XT, Zhang T, Zhang MM, Yi XN, Chen T, Li H, Fan BY, Li YQ. Anterior insular cortex mediates hyperalgesia induced by chronic pancreatitis in rats. Mol Brain 2019; 12:76. [PMID: 31484535 PMCID: PMC6727343 DOI: 10.1186/s13041-019-0497-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 08/23/2019] [Indexed: 12/11/2022] Open
Abstract
Central sensitization plays a pivotal role in the maintenance of chronic pain induced by chronic pancreatitis (CP), but cortical modulation of painful CP remains elusive. This study was designed to examine the role of anterior insular cortex (aIC) in the pathogenesis of hyperalgesia in a rat model of CP. CP was induced by intraductal administration of trinitrobenzene sulfonic acid (TNBS). Abdomen hyperalgesia and anxiety were assessed by von Frey filament and open field tests, respectively. Two weeks after surgery, the activation of aIC was indicated by FOS immunohistochemical staining and electrophysiological recordings. Expressions of VGluT1, NMDAR subunit NR2B and AMPAR subunit GluR1 were analyzed by immunoblottings. The regulatory roles of aIC in hyperalgesia and pain-related anxiety were detected via pharmacological approach and chemogenetics in CP rats. Our results showed that TNBS treatment resulted in long-term hyperalgesia and anxiety-like behavior in rats. CP rats exhibited increased FOS expression and potentiated excitatory synaptic transmission within aIC. CP rats also showed up-regulated expression of VGluT1, and increased membrane trafficking and phosphorylation of NR2B and GluR1 within aIC. Blocking excitatory synaptic transmission significantly attenuated abdomen mechanical hyperalgesia. Specifically inhibiting the excitability of insular pyramidal cells reduced both abdomen hyperalgesia and pain-related anxiety. In conclusion, our findings emphasize a key role for aIC in hyperalgesia and anxiety of painful CP, providing a novel insight into cortical modulation of painful CP and shedding light on aIC as a potential target for neuromodulation interventions in the treatment of CP.
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Affiliation(s)
- Yang Bai
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Li-Tian Ma
- Department of Gastroenterology, Tangdu Hospital, Fourth Military Medical University, Xi'an, 710032, China
| | - Yan-Bing Chen
- Department of Anatomy, Fujian Medical University, Fuzhou, 350108, China
| | - Dan Ren
- Department of Anatomy, Guangxi Medical University, Nanning, 530021, China
| | - Ying-Biao Chen
- Department of Anatomy, Fujian Health College, Fuzhou, 350101, China
| | - Ying-Qi Li
- Department of Cardiology, The Second Affiliated Hospital of Xian Jiaotong University, Xian Jiaotong University, Xi'an, 710004, China
| | - Hong-Ke Sun
- Department of Cardiology, The Second Affiliated Hospital of Xian Jiaotong University, Xian Jiaotong University, Xi'an, 710004, China
| | - Xin-Tong Qiu
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Ting Zhang
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Ming-Ming Zhang
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Xi-Nan Yi
- Joint Laboratory of Neuroscience at Hainan Medical University and Fourth Military Medical University, Hainan Medical University, Haikou, 571199, China
| | - Tao Chen
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Hui Li
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China
| | - Bo-Yuan Fan
- Department of Cardiology, The Second Affiliated Hospital of Xian Jiaotong University, Xian Jiaotong University, Xi'an, 710004, China.
| | - Yun-Qing Li
- Department of Anatomy, Histology and Embryology & K. K. Leung Brain Research Centre, Fourth Military Medical University, No. 169, West Chang-le Road, Xi'an, 710032, China. .,Joint Laboratory of Neuroscience at Hainan Medical University and Fourth Military Medical University, Hainan Medical University, Haikou, 571199, China.
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14
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Tracey I, Woolf CJ, Andrews NA. Composite Pain Biomarker Signatures for Objective Assessment and Effective Treatment. Neuron 2019; 101:783-800. [PMID: 30844399 PMCID: PMC6800055 DOI: 10.1016/j.neuron.2019.02.019] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/05/2019] [Accepted: 02/13/2019] [Indexed: 02/09/2023]
Abstract
Pain is a subjective sensory experience that can, mostly, be reported but cannot be directly measured or quantified. Nevertheless, a suite of biomarkers related to mechanisms, neural activity, and susceptibility offer the possibility-especially when used in combination-to produce objective pain-related indicators with the specificity and sensitivity required for diagnosis and for evaluation of risk of developing pain and of analgesic efficacy. Such composite biomarkers will also provide improved understanding of pain pathophysiology.
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Affiliation(s)
- Irene Tracey
- Nuffield Department of Clinical Neurosciences, University of Oxford, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK.
| | - Clifford J Woolf
- Kirby Neurobiology Center, Boston Children's Hospital and Department of Neurobiology, Harvard Medical School, Boston, 02115 MA, USA.
| | - Nick A Andrews
- Kirby Neurobiology Center, Boston Children's Hospital and Department of Neurobiology, Harvard Medical School, Boston, 02115 MA, USA
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15
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Abstract
Acute pain has an evolutionary role in the detection of physical harm and the response to it. In some cases, however, acute pain can impair function and lead to other morbidities. Chronic pain, meanwhile, can present as a psychopathological condition that significantly interferes with daily living. Most basic and translational pain research has focused on the molecular and cellular mechanisms in the spinal and peripheral nervous systems. In contrast, the brain plays a key role in the affective manifestation and cognitive control of pain. In particular, several cortical regions, such as the somatosensory cortex, prefrontal cortex, insular, and anterior cingulate cortex, are well known to be activated by acute pain signals, and neurons in these regions have been demonstrated to undergo changes in response to chronic pain. Furthermore, these cortical regions can project to a number of forebrain and limbic structures to exert powerful top-down control of not only sensory pain transmission but also affective pain expression, and such cortical regulatory mechanisms are particularly relevant in chronic pain states. Newer techniques have emerged that allow for detailed studies of central pain circuits in animal models, as well as how such circuits are modified by the presence of chronic pain and other predisposing psychosomatic factors. These mechanistic approaches can complement imaging in human studies. At the therapeutic level, a number of pharmacological and nonpharmacological interventions have recently been shown to engage these top-down control systems to provide analgesia. In this review, we will discuss how pain signals reach important cortical regions and how these regions in turn project to subcortical areas of the brain to exert profound modulation of the pain experience. In addition, we will discuss the clinical relevance of such top-down pain regulation mechanisms.
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16
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Chao THH, Chen JH, Yen CT. Plasticity changes in forebrain activity and functional connectivity during neuropathic pain development in rats with sciatic spared nerve injury. Mol Brain 2018; 11:55. [PMID: 30285801 PMCID: PMC6167811 DOI: 10.1186/s13041-018-0398-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/20/2018] [Indexed: 01/08/2023] Open
Abstract
Neuropathic pain is a major worldwide health problem. Although central sensitization has been reported in well-established neuropathic conditions, information on the acute brain activation patterns in response to peripheral nerve injury is lacking. This study first mapped the brain activity in rats immediately following spared nerve injury (SNI) of the sciatic nerve. Using blood-oxygenation-level-dependent functional magnetic resonance imaging (BOLD-fMRI), we observed sustained activation in the bilateral insular cortices (ICs), primary somatosensory cortex (S1), and cingulate cortex. Second, this study sought to link this sustained activation pattern with brain sensitization. Using manganese-enhanced magnetic resonance imaging (MEMRI), we observed enhanced activity in the ipsilateral anterior IC (AIC) in free-moving SNI rats on Days 1 and 8 post-SNI. Furthermore, enhanced functional connectivity between the ipsilateral AIC, bilateral rostral AIC, and S1 was observed on Day 8 post-SNI. Chronic electrophysiological recording experiments were conducted to confirm the tonic neuronal activation in selected brain regions. Our data provide evidence of tonic activation-dependent brain sensitization during neuropathic pain development and offer evidence that the plasticity changes in the IC and S1 may contribute to neuropathic pain development.
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Affiliation(s)
- Tzu-Hao Harry Chao
- Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan
| | - Jyh-Horng Chen
- Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan
| | - Chen-Tung Yen
- Department of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei, 10617, Taiwan.
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17
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NMDA Receptor Dependent Long-term Potentiation in Chronic Pain. Neurochem Res 2018; 44:531-538. [PMID: 30109556 PMCID: PMC6420414 DOI: 10.1007/s11064-018-2614-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/08/2018] [Accepted: 08/11/2018] [Indexed: 02/06/2023]
Abstract
Since the discovery of NMDA receptor (NMDAR) dependent long-term potentiation (LTP) in the hippocampus, many studies have demonstrated that NMDAR dependent LTP exists throughout central synapses, including those involved in sensory transmission and perception. NMDAR LTP has been reported in spinal cord dorsal horn synapses, anterior cingulate cortex and insular cortex. Behavioral, genetic and pharmacological studies show that inhibiting or reducing NMDAR LTP produced analgesic effects in animal models of chronic pain. Investigation of signalling mechanisms for NMDAR LTP may provide novel targets for future treatment of chronic pain.
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18
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Yoon MS, Koh CS, Lee J, Shin J, Kong C, Jung HH, Chang JW. Injecting NMDA and Ro 25-6981 in insular cortex induce neuroplastic changes and neuropathic pain-like behaviour. Eur J Pain 2018; 22:1691-1700. [PMID: 29862605 DOI: 10.1002/ejp.1254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Neuropathic pain is associated with abnormal sensitivity of the central nervous system. Although the mechanism underlying the development of sensitization remains to be fully elucidated, recent studies have reported that neuroplastic changes in the pain circuitry may be involved in hypersensitivity associated with neuropathic pain. However, it is difficult to investigate such phenomena in existing animal pain model. Therefore, in this study, we developed a novel animal model - the circuit plasticity reconstruction (CPR) model - to mimic central sensitization associated with neuroplastic changes. METHOD NMDA and Ro 25-6981 were injected into the right insular cortex of Sprague-Dawley rats, while electrical stimulation was delivered to the contralateral hind paw. Mechanical allodynia was tested by von Frey test with up-down method, and neuroplastic changes were confirmed by PSA-NCAM-positive immunostaining. RESULT The mechanical withdrawal threshold of the left hind paw decreased beginning 1 day after CPR modelling and persisted until day 21 comparing to the modified CPR 1 (mod-CPR 1) group (CPR: 91.68 ± 1.8%, mod-CPR 1: 42.71 ± 3.4%, p < 0.001). In contrast, mod-CPR 2 surgery without electrical stimulation did not induce mechanical allodynia. Immunostaining for PSA-NCAM also revealed that neuroplastic changes had occurred in the CPR group. CONCLUSION Our results demonstrated that CPR modelling induced neuroplasticity within the insular cortex, leading to alterations in the neural circuitry and central sensitization. SIGNIFICANCE This article represents that the CPR model can mimic the neuropathic pain derived by neuroplastic changes. Our findings indicate that the CPR model may aid the development of novel therapeutic strategies for neuropathic pain and in elucidating the mechanisms underlying pain induced by central sensitization and neuroplastic changes.
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Affiliation(s)
- M S Yoon
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - C S Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea
| | - J Lee
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - J Shin
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - C Kong
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea
| | - H H Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
| | - J W Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, South Korea.,Brain Korea 21 PLUS Project for Medical Science and Brain Research Institute, Yonsei University College of Medicine, Seoul, Korea
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19
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Jee Kim M, Tanioka M, Woo Um S, Hong SK, Hwan Lee B. Analgesic effects of FAAH inhibitor in the insular cortex of nerve-injured rats. Mol Pain 2018; 14:1744806918814345. [PMID: 30380982 PMCID: PMC6247483 DOI: 10.1177/1744806918814345] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/10/2018] [Accepted: 09/30/2018] [Indexed: 01/04/2023] Open
Abstract
The insular cortex is an important region of brain involved in the processing of pain and emotion. Recent studies indicate that lesions in the insular cortex induce pain asymbolia and reverse neuropathic pain. Endogenous cannabinoids (endocannabinoids), which have been shown to attenuate pain, are simultaneously degraded by fatty acid amide hydrolase (FAAH) that halts the mechanisms of action. Selective inhibitor URB597 suppresses FAAH activity by conserving endocannabinoids, which reduces pain. The present study examined the analgesic effects of URB597 treatment in the insular cortex of an animal model of neuropathic pain. Under pentobarbital anesthesia, male Sprague-Dawley rats were subjected to nerve injury and cannula implantation. On postoperative day 14, rodents received microinjection of URB597 into the insular cortex. In order to verify the analgesic mechanisms of URB597, cannabinoid 1 receptor (CB1R) antagonist AM251, peroxisome proliferator-activated receptor alpha (PPAR alpha) antagonist GW6471, and transient receptor potential vanilloid 1 (TRPV1) antagonist Iodoresiniferatoxin (I-RTX) were microinjected 15 min prior to URB597 injection. Changes in mechanical allodynia were measured using the von-Frey test. Expressions of CB1R, N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD), and TRPV1 significantly increased in the neuropathic pain group compared to the sham-operated control group. Mechanical threshold and expression of NAPE-PLD significantly increased in groups treated with 2 nM and 4 nM URB597 compared with the vehicle-injected group. Blockages of CB1R and PPAR alpha diminished the analgesic effects of URB597. Inhibition of TRPV1 did not effectively reduce the effects of URB597 but attenuated expression of NAPE-PLD compared with the URB597-injected group. In addition, optical imaging demonstrated that neuronal activity of the insular cortex was reduced following URB597 treatment. Our results suggest that microinjection of FAAH inhibitor into the insular cortex causes analgesic effects by decreasing neural excitability and increasing signals related to the endogenous cannabinoid pathway in the insular cortex.
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Affiliation(s)
- Min Jee Kim
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Motomasa Tanioka
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sun Woo Um
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seong-Karp Hong
- Division of Bio and Health Sciences, Mokwon University, Daejeon, Republic of Korea
| | - Bae Hwan Lee
- Department of Physiology and Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
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20
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The Effect of Electroacupuncture on PKMzeta in the ACC in Regulating Anxiety-Like Behaviors in Rats Experiencing Chronic Inflammatory Pain. Neural Plast 2017; 2017:3728752. [PMID: 29075535 PMCID: PMC5624165 DOI: 10.1155/2017/3728752] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/31/2017] [Accepted: 08/07/2017] [Indexed: 01/26/2023] Open
Abstract
Chronic inflammatory pain can induce emotional diseases. Electroacupuncture (EA) has effects on chronic pain and pain-related anxiety. Protein kinase Mzeta (PKMzeta) has been proposed to be essential for the maintenance of pain and may interact with GluR1 to maintain CNS plasticity in the anterior cingulate cortex (ACC). We hypothesized that the PKMzeta-GluR1 pathway in the ACC may be involved in anxiety-like behaviors of chronic inflammatory pain and that the mechanism of EA regulation of pain emotion may involve the PKMzeta pathway in the ACC. Our results showed that chronic inflammatory pain model decreased the paw withdrawal threshold (PWT) and increased anxiety-like behaviors. The protein expression of PKCzeta, p-PKCzeta (T560), PKMzeta, p-PKMzeta (T560), and GluR1 in the ACC of the model group were remarkably enhanced. EA increased PWT and alleviated anxiety-like behaviors. EA significantly inhibited the protein expression of p-PKMzeta (T560) in the ACC, and only a downward trend effect for other substances. Further, the microinjection of ZIP remarkably reversed PWT and anxiety-like behaviors. The present study provides direct evidence that the PKCzeta/PKMzeta-GluR1 pathway is related to pain and pain-induced anxiety-like behaviors. EA treatment both increases pain-related somatosensory behavior and decreases pain-induced anxiety-like behaviors by suppressing PKMzeta activity in the ACC.
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21
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Yamanaka M, Matsuura T, Pan H, Zhuo M. Calcium-stimulated adenylyl cyclase subtype 1 (AC1) contributes to LTP in the insular cortex of adult mice. Heliyon 2017; 3:e00338. [PMID: 28721398 PMCID: PMC5498404 DOI: 10.1016/j.heliyon.2017.e00338] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/11/2017] [Accepted: 06/22/2017] [Indexed: 12/27/2022] Open
Abstract
Long-term potentiation (LTP) of synaptic transmission in the central nervous system is a key form of cortical plasticity. The insular cortex (IC) is known to play important roles in pain perception, aversive memory and mood disorders. LTP has been recently reported in the IC, however, the signaling pathway for IC LTP remains unknown. Here, we investigated the synaptic mechanism of IC LTP. We found that IC LTP induced by the pairing protocol was N-methyl-D-aspartate receptors (NMDARs) dependent, and expressed postsynaptically, since paired-pulse ratio (PPR) was not affected. Postsynaptic calcium is important for the induction of post-LTP, since the postsynaptic application of BAPTA completely blocked the induction of LTP. Calcium-activated adenylyl cyclase subtype 1 (AC1) is required for potentiation. By contrast, AC8 is not required. Inhibition of Ca2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (CP-AMPARs) or protein kinase M zeta (PKMζ) reduced the expression of LTP. Our results suggest that calcium-stimulated AC1, but not AC8, can be a trigger of the induction and maintenance of LTP in the IC.
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Affiliation(s)
- Manabu Yamanaka
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, Shanxi 710049, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.,Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, 641-8509, Japan
| | - Takanori Matsuura
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, Shanxi 710049, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Haili Pan
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, Shanxi 710049, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
| | - Min Zhuo
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an, Shanxi 710049, China.,Department of Physiology, Faculty of Medicine, University of Toronto, Medical Science Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada
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22
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PKMζ Is Not Required for Development of Postsurgical Pain. Mol Neurobiol 2017; 55:2397-2402. [PMID: 28357808 DOI: 10.1007/s12035-017-0499-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/16/2017] [Indexed: 10/19/2022]
Abstract
Previous studies have shown that protein kinase M zeta (PKMζ), a brain-specific isoform of protein kinase C, is involved in the central processing of nociception in several pain models by using a synthetic zeta inhibitory peptide. In the present study, we investigated whether PKMζ contributes to the pathogenesis of postsurgical pain using both conditional and conventional PKMζ knockout mice. Our results showed that the expression of PKMζ in anterior cingulate cortex, but not spinal cord, of the conditional PKMζ knockout mice was inhibited following tamoxifen injection. And the conditional PKMζ knockout mice displayed similar plantar incision-produced postsurgical pain responses as those in wild-type mice. Moreover, the expression of PKMζ was inhibited in both anterior cingulate cortex and spinal cord of the conventional PKMζ knockout mice. And there were no significant differences in the development of postsurgical pain among wild-type, heterozygous, and homozygous conventional PKMζ knockout mice. These data suggest that PKMζ is not required for the development of postsurgical pain after plantar incision.
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23
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Kwon M, Han J, Kim UJ, Cha M, Um SW, Bai SJ, Hong SK, Lee BH. Inhibition of Mammalian Target of Rapamycin (mTOR) Signaling in the Insular Cortex Alleviates Neuropathic Pain after Peripheral Nerve Injury. Front Mol Neurosci 2017; 10:79. [PMID: 28377693 PMCID: PMC5359287 DOI: 10.3389/fnmol.2017.00079] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 03/06/2017] [Indexed: 12/30/2022] Open
Abstract
Injury of peripheral nerves can trigger neuropathic pain, producing allodynia and hyperalgesia via peripheral and central sensitization. Recent studies have focused on the role of the insular cortex (IC) in neuropathic pain. Because the IC is thought to store pain-related memories, translational regulation in this structure may reveal novel targets for controlling chronic pain. Signaling via mammalian target of rapamycin (mTOR), which is known to control mRNA translation and influence synaptic plasticity, has been studied at the spinal level in neuropathic pain, but its role in the IC under these conditions remains elusive. Therefore, this study was conducted to determine the role of mTOR signaling in neuropathic pain and to assess the potential therapeutic effects of rapamycin, an inhibitor of mTORC1, in the IC of rats with neuropathic pain. Mechanical allodynia was assessed in adult male Sprague-Dawley rats after neuropathic surgery and following microinjections of rapamycin into the IC on postoperative days (PODs) 3 and 7. Optical recording was conducted to observe the neural responses of the IC to peripheral stimulation. Rapamycin reduced mechanical allodynia and downregulated the expression of postsynaptic density protein 95 (PSD95), decreased neural excitability in the IC, thereby inhibiting neuropathic pain-induced synaptic plasticity. These findings suggest that mTOR signaling in the IC may be a critical molecular mechanism modulating neuropathic pain.
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Affiliation(s)
- Minjee Kwon
- Department of Physiology, Yonsei University College of MedicineSeoul, South Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of MedicineSeoul, South Korea
| | - Jeongsoo Han
- Department of Physiology, Yonsei University College of MedicineSeoul, South Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of MedicineSeoul, South Korea
| | - Un Jeng Kim
- Department of Physiology, Yonsei University College of Medicine Seoul, South Korea
| | - Myeounghoon Cha
- Department of Physiology, Yonsei University College of Medicine Seoul, South Korea
| | - Sun Woo Um
- Department of Physiology, Yonsei University College of MedicineSeoul, South Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of MedicineSeoul, South Korea
| | - Sun Joon Bai
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine Seoul, South Korea
| | - Seong-Karp Hong
- Division of Bio and Health Sciences, Mokwon University Daejeon, South Korea
| | - Bae Hwan Lee
- Department of Physiology, Yonsei University College of MedicineSeoul, South Korea; Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of MedicineSeoul, South Korea; Brain Research Institute and Epilepsy Research Institute, Yonsei University College of MedicineSeoul, South Korea
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24
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Zhang PA, Xu QY, Xue L, Zheng H, Yan J, Xiao Y, Xu GY. Neonatal Maternal Deprivation Enhances Presynaptic P2X7 Receptor Transmission in Insular Cortex in an Adult Rat Model of Visceral Hypersensitivity. CNS Neurosci Ther 2016; 23:145-154. [PMID: 27976523 DOI: 10.1111/cns.12663] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 10/06/2016] [Accepted: 11/11/2016] [Indexed: 12/12/2022] Open
Abstract
AIMS Insular cortex (IC) is involved in processing the information of pain. The aim of this study was to investigate roles and mechanisms of P2X7 receptors (P2X7Rs) in IC in development of visceral hypersensitivity of adult rats with neonatal maternal deprivation (NMD). METHODS Visceral hypersensitivity was quantified by abdominal withdrawal reflex threshold to colorectal distension (CRD). Expression of P2X7Rs was determined by qPCR and Western blot. Synaptic transmission in IC was recorded by patch-clamp recording. RESULTS The expression of P2X7Rs and glutamatergic neurotransmission in IC was significantly increased in NMD rats when compared with age-matched controls. Application of BzATP (P2X7R agonist) enhanced the frequency of spontaneous excitatory postsynaptic currents (sEPSC) and miniature excitatory postsynaptic currents (mEPSC) in IC slices of control rats. Application of BBG (P2X7R antagonist) suppressed the frequencies of sEPSC and mEPSC in IC slices of NMD rats. Microinjection of BzATP into right IC significantly decreased CRD threshold in control rats while microinjection of BBG or A438079 into right IC greatly increased CRD threshold in NMD rats. CONCLUSION Data suggested that the enhanced activities of P2X7Rs in IC, likely through a presynaptic mechanism, contributed to visceral hypersensitivity of adult rats with NMD.
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Affiliation(s)
- Ping-An Zhang
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China
| | - Qi-Ya Xu
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China
| | - Lu Xue
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China
| | - Hang Zheng
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China
| | - Jun Yan
- The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Ying Xiao
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China.,Chengdu Radio and TV University, Chengdu, China
| | - Guang-Yin Xu
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Laboratory of Translational Pain Medicine, Institute of Neuroscience, Soochow University, Suzhou, China
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25
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Zhuo M. Contribution of synaptic plasticity in the insular cortex to chronic pain. Neuroscience 2016; 338:220-229. [PMID: 27530697 DOI: 10.1016/j.neuroscience.2016.08.014] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/03/2016] [Accepted: 08/04/2016] [Indexed: 12/20/2022]
Abstract
Animal and human studies have consistently demonstrated that cortical regions are important for pain perception and pain-related emotional changes. Studies of the anterior cingulate cortex (ACC) have shown that adult cortical synapses can be modified after peripheral injuries, and long-term changes at synaptic level may contribute to long-lasting suffering in patients. It also explains why chronic pain is resistant to conventional analgesics that act by inhibiting synaptic transmission. Insular cortex (IC), another critical cortical area, is found to be highly plastic and can undergo long-term potentiation (LTP) after injury. Inhibiting IC LTP reduces behavioral sensitization caused by injury. LTP of glutamatergic transmission in pain related cortical areas serves as a key mechanism for chronic pain.
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Affiliation(s)
- Min Zhuo
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China; Centre for the Study of Pain, University of Toronto, Ontario M5S 1A8, Canada.
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