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Inami C, Haruta M, Ohta Y, Tanaka M, So M, Sobue K, Akay Y, Kume K, Ohta J, Akay M, Ohsawa M. Real-time monitoring of cortical brain activity in response to acute pain using wide-area Ca 2+ imaging. Biochem Biophys Res Commun 2024; 708:149800. [PMID: 38522402 DOI: 10.1016/j.bbrc.2024.149800] [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: 02/15/2024] [Accepted: 03/16/2024] [Indexed: 03/26/2024]
Abstract
Previous human and rodent studies indicated that nociceptive stimuli activate many brain regions that is involved in the somatosensory and emotional sensation. Although these studies have identified several important brain regions involved in pain perception, it has been a challenge to observe neural activity directly and simultaneously in these multiple brain regions during pain perception. Using a transgenic mouse expressing G-CaMP7 in majority of astrocytes and a subpopulation of excitatory neurons, we recorded the brain activity in the mouse cerebral cortex during acute pain stimulation. Both of hind paw pinch and intraplantar administration of formalin caused strong transient increase of the fluorescence in several cortical regions, including primary somatosensory, motor and retrosplenial cortex. This increase of the fluorescence intensity was attenuated by the pretreatment with morphine. The present study provides important insight into the cortico-cortical network during pain perception.
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Affiliation(s)
- Chihiro Inami
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan
| | - Makito Haruta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma-shi, Nara, Japan
| | - Yasumi Ohta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma-shi, Nara, Japan
| | - Motoshi Tanaka
- Department of Anesthesiology and Intensive Care Medicine, Graduate School of Medicine. Nagoya City University, 1 Kawasumi, Mizuho-ku, Nagoya, 467-8601, Japan
| | - MinHye So
- Department of Anesthesiology and Intensive Care Medicine, Graduate School of Medicine. Nagoya City University, 1 Kawasumi, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Kazuya Sobue
- Department of Anesthesiology and Intensive Care Medicine, Graduate School of Medicine. Nagoya City University, 1 Kawasumi, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Yasemin Akay
- Biomedical Engineering Department, University of Houston, 3517 Cullen Blvd, Houston, TX, 77204, USA
| | - Kazuhiko Kume
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan
| | - Jun Ohta
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma-shi, Nara, Japan
| | - Metin Akay
- Biomedical Engineering Department, University of Houston, 3517 Cullen Blvd, Houston, TX, 77204, USA
| | - Masahiro Ohsawa
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan; Department of Integrative Neuroscience, National Center for Geriatrics and Gerontology, Obu, Aichi, 474-8511, Japan; Laboratory of Systems Pharmacology, Faculty of Pharma-Sciences, Teikyo University, Itabashi, Tokyo, 173-8603, Japan.
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Diniz DM, Malamut C, Araújo MR, Ferreira AV, Silva JF, Cordeiro MDN, Borges MH, Romano Silva MA, Gomez MV, Castro Junior CJ. Mapping of Brain Activity in the Analgesia Induced by Phα1β and Morphine. Front Mol Biosci 2022; 8:770471. [PMID: 35187065 PMCID: PMC8855152 DOI: 10.3389/fmolb.2021.770471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/27/2021] [Indexed: 12/03/2022] Open
Abstract
Preclinical evidence suggests the potential of Phα1β, a toxin obtained from the venom of spider Phoneutria nigriventer, as a new analgesic drug. Molecular brain imaging techniques have afforded exciting opportunities to examine brain processes in clinical pain conditions. This paper aims to study the brain regions involved in the analgesic effects of Phα1β compared with Morphine, in a model of acute pain induced by formalin in Sprague Dawley rats. We used 18F-fluorodeoxyglucose as a metabolic radiotracer to perform brain imaging of rats pretreated with Phα1β or Morphine in a model of acute inflammatory pain caused by intraplantar injection of formalin. The rats’ hind paw’s formalin stimulation resulted in a brain metabolic increase at the bilateral motor cortex, visual cortex, somatosensory cortex, thalamus, and cingulate cortex.In rats treated with Phα1β, selective inhibition of unilateral motor cortex and cingulate cortex was observed. Morphine treatment leads to small and selective inhibition at the bilateral amygdala striatum and accumbens. Our results indicate that the analgesic effect of Phα1β and Morphine possesses a differential profile of central processing in the pain state.
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Affiliation(s)
- Danuza Montijo Diniz
- Department of Neurotransmitters, Santa Casa, Institute of Education and Research, Belo Horizonte, Brazil
| | - Carlos Malamut
- Radiobiology Department, Center for the Development of Nuclear Technology, National Commission of Nuclear Energy (CDTN/CNEN), Belo Horizonte, Brazil
| | - Marina Rios Araújo
- Radiobiology Department, Center for the Development of Nuclear Technology, National Commission of Nuclear Energy (CDTN/CNEN), Belo Horizonte, Brazil
| | - Andrea Vidal Ferreira
- Radiobiology Department, Center for the Development of Nuclear Technology, National Commission of Nuclear Energy (CDTN/CNEN), Belo Horizonte, Brazil
| | - Juliana Figueira Silva
- Department of Neurotransmitters, Santa Casa, Institute of Education and Research, Belo Horizonte, Brazil
| | | | | | - Marco Aurélio Romano Silva
- Department of Mental Health, Faculty of Medicine, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Marcus Vinicius Gomez
- Department of Neurotransmitters, Santa Casa, Institute of Education and Research, Belo Horizonte, Brazil
| | - Célio Jose Castro Junior
- Department of Neurotransmitters, Santa Casa, Institute of Education and Research, Belo Horizonte, Brazil
- *Correspondence: Célio Jose Castro Junior,
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Wu CY, Lin YH, Hsieh HH, Lin JJ, Peng SL. Sex Differences in the Effect of Diabetes on Cerebral Glucose Metabolism. Biomedicines 2021; 9:1661. [PMID: 34829890 PMCID: PMC8615590 DOI: 10.3390/biomedicines9111661] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 12/25/2022] Open
Abstract
The neuroimaging literature indicates that brain structure and function both deteriorate with diabetes, but information on sexual dimorphism in diabetes-related brain alterations is limited. This study aimed to ascertain whether brain metabolism is influenced by sex in an animal model of diabetes. Eleven rats (male, n = 5; female, n = 6) received a single intraperitoneal injection of 70 mg/kg streptozotocin (STZ) to develop diabetes. Another 11 rats (male, n = 5; female, n = 6) received the same amount of solvent through a single intraperitoneal injection. Longitudinal positron emission tomography scans were used to assess cerebral glucose metabolism before and 4 weeks after STZ or solvent administration. Before STZ or solvent injections, there was no evidence of sexual dimorphism in cerebral metabolism (p > 0.05). Compared with healthy control animals, rats with diabetes had significantly decreased brain metabolism in all brain regions (all p < 0.05). In addition, female diabetic rats exhibited further reduction in cerebral metabolism, relative to male diabetic rats (p < 0.05). The results of this study may provide some biological evidence, supporting the existence of a sexual dimorphism in diabetes-related complications.
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Affiliation(s)
- Chun-Yi Wu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei Branch, Taipei 112304, Taiwan; (C.-Y.W.); (H.-H.H.)
| | - Yu-Hsin Lin
- Department of Pharmacy, National Yang Ming Chiao Tung University, Taipei Branch, Taipei 112304, Taiwan;
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 404333, Taiwan
| | - Hsin-Hua Hsieh
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei Branch, Taipei 112304, Taiwan; (C.-Y.W.); (H.-H.H.)
| | - Jia-Jia Lin
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, Taoyuan 404333, Taiwan;
| | - Shin-Lei Peng
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung 404332, Taiwan
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D'Elia A, Schiavi S, Soluri A, Massari R, Soluri A, Trezza V. Role of Nuclear Imaging to Understand the Neural Substrates of Brain Disorders in Laboratory Animals: Current Status and Future Prospects. Front Behav Neurosci 2020; 14:596509. [PMID: 33362486 PMCID: PMC7759612 DOI: 10.3389/fnbeh.2020.596509] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
Molecular imaging, which allows the real-time visualization, characterization and measurement of biological processes, is becoming increasingly used in neuroscience research. Scintigraphy techniques such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) provide qualitative and quantitative measurement of brain activity in both physiological and pathological states. Laboratory animals, and rodents in particular, are essential in neuroscience research, providing plenty of models of brain disorders. The development of innovative high-resolution small animal imaging systems together with their radiotracers pave the way to the study of brain functioning and neurotransmitter release during behavioral tasks in rodents. The assessment of local changes in the release of neurotransmitters associated with the performance of a given behavioral task is a turning point for the development of new potential drugs for psychiatric and neurological disorders. This review addresses the role of SPECT and PET small animal imaging systems for a better understanding of brain functioning in health and disease states. Brain imaging in rodent models faces a series of challenges since it acts within the boundaries of current imaging in terms of sensitivity and spatial resolution. Several topics are discussed, including technical considerations regarding the strengths and weaknesses of both technologies. Moreover, the application of some of the radioligands developed for small animal nuclear imaging studies is discussed. Then, we examine the changes in metabolic and neurotransmitter activity in various brain areas during task-induced neural activation with special regard to the imaging of opioid, dopaminergic and cannabinoid receptors. Finally, we discuss the current status providing future perspectives on the most innovative imaging techniques in small laboratory animals. The challenges and solutions discussed here might be useful to better understand brain functioning allowing the translation of preclinical results into clinical applications.
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Affiliation(s)
- Annunziata D'Elia
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy.,Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Sara Schiavi
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
| | - Andrea Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Roberto Massari
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Alessandro Soluri
- Institute of Biochemistry and Cell Biology, National Research Council of Italy (CNR), Rome, Italy
| | - Viviana Trezza
- Section of Biomedical Sciences and Technologies, Department of Science, University "Roma Tre", Rome, Italy
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Peng SL, Chiu H, Wu CY, Huang CW, Chung YH, Shih CT, Shen WC. The effect of caffeine on cerebral metabolism during alpha-chloralose anesthesia differs from isoflurane anesthesia in the rat brain. Psychopharmacology (Berl) 2019; 236:1749-1757. [PMID: 30604185 DOI: 10.1007/s00213-018-5157-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 12/19/2018] [Indexed: 10/27/2022]
Abstract
RATIONALE Caffeine is a widely studied psychostimulant, even though its exact effect on brain activity remains to be elucidated. Positron emission tomography (PET) allows studying mechanisms underlying cerebral metabolic responses to caffeine in caffeine-naïve rats. Rodent studies are typically performed under anesthesia. However, the anesthesia may affect neurotransmitter systems targeted by tested drugs. OBJECTIVES The scope of the present study was to address the impairing or enhancing effect of two common anesthetics, alpha-chloralose and isoflurane, on the kinetics of caffeine. METHODS The first group of rats (n = 15) were anesthetized under 1.5% isoflurane anesthesia. The second group of rats (n = 15) were anesthetized under alpha-chloralose (80 mg/kg). These rats received an intravenous injection of saline (n = 5) or of 2.5 mg/kg (n = 5) or 40 mg/kg (n = 5) caffeine for both groups. RESULTS With 2.5 mg/kg or 40 mg/kg caffeine, whole-brain cerebral metabolism was significantly reduced by 17.2% and 17% (both P < 0.01), respectively, under alpha-chloralose anesthesia. However, the lower dose of caffeine (2.5 mg/kg) had a limited effect on brain metabolism, whereas its higher dose (40 mg/kg) produced enhancements in brain metabolism in the striatum, hippocampus, and thalamus (all P < 0.05) under isoflurane anesthesia. CONCLUSION These findings demonstrate significant differences in brain responses to caffeine on the basic of the anesthesia regimen used, which highlights the importance of attention to the anesthetic used when interpreting findings from animal pharmacological studies because of possible interactions between the anesthetic and the drug under study.
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Affiliation(s)
- Shin-Lei Peng
- Department of Biomedical Imaging and Radiological Science, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan.
| | - Han Chiu
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Chun-Yi Wu
- Department of Biomedical Imaging and Radiological Science, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan
| | - Chiun-Wei Huang
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Yi-Hsiu Chung
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Cheng-Ting Shih
- Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Wu-Chung Shen
- Department of Biomedical Imaging and Radiological Science, China Medical University, 91 Hsueh-Shih Road, Taichung, 40402, Taiwan.,Department of Radiology, China Medical University Hospital, Taichung, Taiwan
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Chen A, Chen Y, Tang Y, Bao C, Cui Z, Xiao M, Lin C. Hippocampal AMPARs involve the central sensitization of rats with irritable bowel syndrome. Brain Behav 2017; 7:e00650. [PMID: 28293483 PMCID: PMC5346530 DOI: 10.1002/brb3.650] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/29/2016] [Accepted: 12/22/2016] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE The roles of hippocampal AMPARs were investigated in irritable bowel syndrome (IBS)-like rats to clarify the central sensitization mechanisms. METHODS IBS model was induced by neonatal maternal separation. The effects of AMPARs on visceral hypersensitivity were examined by the responses of abdominal muscle to colorectal distension after the bilateral intrahippocampal injections of CNQX (an AMPAR inhibitor). The expressions of hippocampal AMPARs (GluR1 and GluR2) were determined by Western blot. RESULTS The IBS-like rats showed visceral hypersensitivity when compared with controls. Bilateral intrahippocampal injections of CNQX alleviated the visceral pain in IBS-like rats. The maximal effect appeared at the time point of 30 min, and the duration lasted for 90 min after CNQX application, under 40 and 60 mmHg CRD. The expressions of hippocampal GluR2 significantly increased in IBS-like rats when compared with controls (p < .05). However, the levels of hippocampal GluR1 had no significant differences in rats. Hippocampal LTP induced by HFS was significantly enhanced when compared with controls (p < .05). The expressions of GluR2 significantly increased in the control and IBS-like rats after 60 min LTP of recordings (p < .05), but not GluR1. CONCLUSION Neonatal maternal separation enhances the expression of GluR2 and facilitates the LTP in the hippocampus, which could lead to the formation of visceral hypersensitivity when grown up.
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Affiliation(s)
- Aiqin Chen
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
| | - Yu Chen
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
| | - Ying Tang
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
| | - Chengjia Bao
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
| | - Zizhi Cui
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
| | - Meng Xiao
- 2013 Seven‐year Clinical MedicineFujian Medical UniversityFuzhouFujianChina
| | - Chun Lin
- Fujian Provincial Key Laboratory of Neuroglia and DiseasesLaboratory of Pain ResearchDepartment of Physiology and PathophysiologyFujian Medical UniversityFuzhouFujianChina
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GABA acting on GABAB receptors located in a medullary pain facilitatory area enhances nociceptive behaviors evoked by intraplantar formalin injection. Pain 2016; 156:1555-1565. [PMID: 25932688 DOI: 10.1097/j.pain.0000000000000203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The dorsal reticular nucleus (DRt) plays a key role in facilitation of nociceptive transmission at the spinal cord. In this study, we evaluated the mechanisms involved in GABA-mediated control of the DRt focusing on the role of local GABAB receptors. First, we used in vivo microdialysis to study the release of GABA in the DRt during the course of the formalin test. An increase of GABA levels in comparison with baseline values was detected in the second phase of the test. Because we previously showed that GABAB receptors are expressed by opioidergic DRt neurons, which respond to nociceptive stimuli and inhibit spinally projecting DRt neurons involved in descending pronociception, we then interfered with local GABAB receptors using gene transfer and pharmacological approaches. Lentiviral-mediated knockdown of GABAB1a expression decreased nociceptive responses during the second phase of the test. Local administration of the GABAB receptor antagonist CGP 35348 also decreased nociceptive responses in the second phase of the test, whereas the opposite was detected after injection of the GABAB agonist baclofen. Finally, we determined the GABAergic afferents of the DRt, namely those arising from its main brain afferents, which are located at the telencephalon and diencephalon. For that purpose, we combined retrograde tract-tracing from the DRt with immunodetection of glutamate decarboxylase, the GABA-synthesizing enzyme. The higher numbers of retrogradely labelled glutamate decarboxylase-immunoreactive neurons were located at insular, somatosensory, and motor cortices. Collectively, the results suggest that GABA acting on GABAB receptors may enhance pain facilitation from the DRt during inflammatory pain.
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Malheiros JM, Guinsburg R, Covolan L. Cortical modulation of pain: comments on "exacerbation of tonic but not phasic pain by entorhinal cortex lesions". Neurosci Lett 2014; 581:135-6. [PMID: 25128752 DOI: 10.1016/j.neulet.2014.08.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 08/05/2014] [Indexed: 01/21/2023]
Affiliation(s)
| | - Ruth Guinsburg
- Department of Pediatrics, Universidade Federal de São Paulo - UNIFESP, São Paulo 04023-062, Brazil
| | - Luciene Covolan
- Departmento of Phyisiology, Universidade Federal de São Paulo - UNIFESP, São Paulo 04023-062, Brazil.
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Lin HC, Huang YH, Chao THH, Lin WY, Sun WZ, Yen CT. Gabapentin reverses central hypersensitivity and suppresses medial prefrontal cortical glucose metabolism in rats with neuropathic pain. Mol Pain 2014; 10:63. [PMID: 25253440 PMCID: PMC4182821 DOI: 10.1186/1744-8069-10-63] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 09/10/2014] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Gabapentin (GBP) is known to suppress neuropathic hypersensitivity of primary afferents and the spinal cord dorsal horn. However, its supra-spinal action sites are unclear. We identify the brain regions where GBP changes the brain glucose metabolic rate at the effective dose that alleviates mechanical allodynia using 18 F-fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning. RESULTS Comparing the PET imaging data before and after the GBP treatment, the spared nerve injury-induced increases of glucose metabolism in the thalamus and cerebellar vermis were reversed, and a significant decrease occurred in glucose metabolism in the medial prefrontal cortex (mPFC), including the anterior cingulate cortex. GBP treatment also reversed post-SNI connectivity increases between limbic cortices and thalamus. CONCLUSIONS Our results indicate that GBP analgesic effect may be mediated by reversing central hypersensitivity, and suppressing mPFC, a crucial part of the cortical representation of pain, in the brain.
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Affiliation(s)
- Hsiao-Chun Lin
- />Department of Life Science, National Taiwan University, No 1, Section 4, Roosevelt Road, Taipei, 10617 Taiwan
| | - Yu-Hsin Huang
- />Department of Anesthesiology, National Taiwan University Hospital, Taipei, 10002 Taiwan
| | - Tzu-Hao Harry Chao
- />Department of Life Science, National Taiwan University, No 1, Section 4, Roosevelt Road, Taipei, 10617 Taiwan
| | - Wen-Ying Lin
- />Department of Life Science, National Taiwan University, No 1, Section 4, Roosevelt Road, Taipei, 10617 Taiwan
- />Department of Anesthesiology, National Taiwan University Hospital, Taipei, 10002 Taiwan
| | - Wei-Zen Sun
- />Department of Anesthesiology, National Taiwan University Hospital, Taipei, 10002 Taiwan
| | - Chen-Tung Yen
- />Department of Life Science, National Taiwan University, No 1, Section 4, Roosevelt Road, Taipei, 10617 Taiwan
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Imaging neurovascular function and functional recovery after stroke in the rat striatum using forepaw stimulation. J Cereb Blood Flow Metab 2014; 34:1483-92. [PMID: 24917039 PMCID: PMC4158660 DOI: 10.1038/jcbfm.2014.103] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 05/05/2014] [Accepted: 05/07/2014] [Indexed: 12/19/2022]
Abstract
Negative functional magnetic resonance imaging (fMRI) response in the striatum has been observed in several studies during peripheral sensory stimulation, but its relationship between local field potential (LFP) remains to be elucidated. We performed cerebral blood volume (CBV) fMRI and LFP recordings in normal rats during graded noxious forepaw stimulation at nine stimulus pulse widths. Albeit high LFP-CBV correlation was found in the ipsilateral and contralateral sensory cortices (r=0.89 and 0.95, respectively), the striatal CBV responses were neither positively, nor negatively correlated with LFP (r=0.04), demonstrating that the negative striatal CBV response is not originated from net regional inhibition. To further identify whether this negative CBV response can serve as a marker for striatal functional recovery, two groups of rats (n=5 each) underwent 20- and 45-minute middle cerebral artery occlusion (MCAO) were studied. No CBV response was found in the ipsilateral striatum in both groups immediately after stroke. Improved striatal CBV response was observed on day 28 in the 20-minute MCAO group compared with the 45-minute MCAO group (P<0.05). This study shows that fMRI signals could differ significantly from LFP and that the observed negative CBV response has potential to serve as a marker for striatal functional integrity in rats.
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Lu YF, Wang Y, He Y, Zhang FK, He T, Wang RR, Chen XF, Yang F, Gong KR, Chen J. Spatial and temporal plasticity of synaptic organization in anterior cingulate cortex following peripheral inflammatory pain: multi-electrode array recordings in rats. Neurosci Bull 2014; 30:1-20. [PMID: 23686522 PMCID: PMC5561851 DOI: 10.1007/s12264-013-1344-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 04/19/2013] [Indexed: 12/23/2022] Open
Abstract
To explore whether experiencing inflammatory pain has an impact upon intracortical synaptic organization, the planar multi-electrode array (MEA) technique and 2-dimensional current source density (2D-CSD) imaging were used in slice preparations of the anterior cingulate cortex (ACC) from rats. Synaptic activity across different layers of the ACC was evoked by deep layer stimulation through one electrode. The layer-localization of both local field potentials (LFPs) and the spread of current sink calculated by 2D-CSD analysis was characterized pharmacologically. Moreover, the induction of long-term potentiation (LTP) and changes in LTP magnitude were also evaluated. We found that under naïve conditions, the current sink was initially generated in layer VI, then spread to layer V and finally confined to layers II-III. This spatial pattern of current sink movement typically reflected changes in depolarized sites from deep layers (V-VI) to superficial layers (II-III) where intra- and extracortical inputs terminate. In the ACC slices from rats in an inflamed state (for 2 h) caused by intraplantar bee-venom injection, the spatial profile of intra-ACC synaptic organization was significantly changed, showing an enlarged current sink distribution and a leftward shift of the stimulus-response curves relative to the naïve and saline controls. The change was more distinct in the superficial layers (II-III) than in the deep site. In terms of temporal properties, the rate of LTP induction was significantly increased in layers II-III by inflammatory pain. However, the magnitude of LTP was not significantly enhanced by this treatment. Taken together, these results show that inflammatory pain results in distinct spatial and temporal plasticity of synaptic organization in the ACC, which may lead to altered synaptic transmission and modulation.
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Affiliation(s)
- Yun-Fei Lu
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
| | - Yan Wang
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
| | - Ying He
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, 100069 China
| | - Fu-Kang Zhang
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, 100069 China
| | - Ting He
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
| | - Rui-Rui Wang
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, 100069 China
| | - Xue-Feng Chen
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
| | - Fei Yang
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
| | - Ke-Rui Gong
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, 100069 China
| | - Jun Chen
- Institute for Biomedical Sciences of Pain and Institute for Functional Brain Disorders, Tangdu Hospital, The Fourth Military Medical University, Xi’an, 710038 China
- Key Laboratory of Brain Stress and Behavior, PLA, Xi’an, 710038 China
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, 100069 China
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Yen CT, Lu PL. Thalamus and pain. ACTA ACUST UNITED AC 2013; 51:73-80. [DOI: 10.1016/j.aat.2013.06.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 05/13/2013] [Indexed: 02/02/2023]
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13
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Li J, Gu L, Feng DF, Ding F, Zhu G, Rong J. Exploring temporospatial changes in glucose metabolic disorder, learning, and memory dysfunction in a rat model of diffuse axonal injury. J Neurotrauma 2013; 29:2635-46. [PMID: 22880625 DOI: 10.1089/neu.2012.2411] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Diffuse axonal injury (DAI) is the predominant effect of severe traumatic brain injury and contributes significantly to cognitive deficits. The mechanisms underlying these cognitive deficits are often associated with complex metabolic alterations. However, the relationships between temporospatial alterations in cerebral glucose metabolism and the pathophysiology of DAI-related learning and memory dysfunction are not yet completely understood. We used a small animal positron emission tomography (PET) scanner with 2-[F-18]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) as a molecular probe to evaluate temporospatial glucose metabolism in vulnerable areas of rats with DAI. The Morris water maze (MWM) was used to evaluate the development and progression of learning and memory dysfunction. Compared to the sham-treated group, PET-MRI fusion images showed that glucose metabolism was reduced in animals with DAI. In addition, the standardized uptake value (SUV) of ¹⁸F-FDG was significantly decreased in the sensorimotor cortex, hippocampus, corpus callosum, caudate putamen, brain stem, and cerebellum at days 1, 3, and 7 after injury. SUV returned to baseline levels by 30 days after injury. The escape latency of the injured group was significantly increased, and the percentages of distance travelled and time spent in the target quadrant were significantly decreased 1 month after injury. These effects persisted for 3 months. SUVs in the hippocampus at the acute stage were significantly correlated with MWM performance during the recovery stage of DAI. These results demonstrate that microstructural injury-induced hypometabolism in the hippocampus at the acute stage are all significantly correlated with learning and memory dysfunctions during the recovery stage of DAI.
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Affiliation(s)
- Jia Li
- Department of Neurosurgery, No. 3 People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
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14
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Paldy E, Borcel E, Higuera-Matas A, López-Montoya G, Wenger T, Toth G, Borsodi A, Ambrosio E. CNR1 gene deletion affects the density of endomorphin-2 binding sites in the mouse brain in a hemisphere-specific manner. Eur J Pharmacol 2013; 698:220-7. [DOI: 10.1016/j.ejphar.2012.10.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Revised: 10/27/2012] [Accepted: 10/31/2012] [Indexed: 11/29/2022]
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Hayes DJ, Northoff G. Common brain activations for painful and non-painful aversive stimuli. BMC Neurosci 2012; 13:60. [PMID: 22676259 PMCID: PMC3464596 DOI: 10.1186/1471-2202-13-60] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 04/18/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Identification of potentially harmful stimuli is necessary for the well-being and self-preservation of all organisms. However, the neural substrates involved in the processing of aversive stimuli are not well understood. For instance, painful and non-painful aversive stimuli are largely thought to activate different neural networks. However, it is presently unclear whether there is a common aversion-related network of brain regions responsible for the basic processing of aversive stimuli. To help clarify this issue, this report used a cross-species translational approach in humans (i.e. meta-analysis) and rodents (i.e. systematic review of functional neuroanatomy). RESULTS Animal and human data combined to show a core aversion-related network, consisting of similar cortical (i.e. MCC, PCC, AI, DMPFC, RTG, SMA, VLOFC; see results section or abbreviation section for full names) and subcortical (i.e. Amyg, BNST, DS, Hab, Hipp/Parahipp, Hyp, NAc, NTS, PAG, PBN, raphe, septal nuclei, Thal, LC, midbrain) regions. In addition, a number of regions appeared to be more involved in pain-related (e.g. sensory cortex) or non-pain-related (e.g. amygdala) aversive processing. CONCLUSIONS This investigation suggests that aversive processing, at the most basic level, relies on similar neural substrates, and that differential responses may be due, in part, to the recruitment of additional structures as well as the spatio-temporal dynamic activity of the network. This network perspective may provide a clearer understanding of why components of this circuit appear dysfunctional in some psychiatric and pain-related disorders.
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Affiliation(s)
- Dave J Hayes
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
| | - Georg Northoff
- Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health Research, University of Ottawa, 1145 Carling Avenue, Ottawa, K1Z 7K4, Canada
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16
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Thompson SJ, Bushnell MC. Rodent functional and anatomical imaging of pain. Neurosci Lett 2012; 520:131-9. [PMID: 22445887 DOI: 10.1016/j.neulet.2012.03.015] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 03/06/2012] [Accepted: 03/07/2012] [Indexed: 02/07/2023]
Abstract
Human brain imaging has provided much information about pain processing and pain modulation, but brain imaging in rodents can provide information not attainable in human studies. First, the short lifespan of rats and mice, as well as the ability to have homogenous genetics and environments, allows for longitudinal studies of the effects of chronic pain on the brain. Second, brain imaging in animals allows for the testing of central actions of novel pharmacological and nonpharmacological analgesics before they can be tested in humans. The two most commonly used brain imaging methods in rodents are magnetic resonance imaging (MRI) and positron emission tomography (PET). MRI provides better spatial and temporal resolution than PET, but PET allows for the imaging of neurotransmitters and non-neuronal cells, such as astrocytes, in addition to functional imaging. One problem with rodent brain imaging involves methods for keeping the subject still in the scanner. Both anesthetic agents and restraint techniques have potential confounds. Some PET methods allow for tracer uptake before the animal is anesthetized, but imaging a moving animal also has potential confounds. Despite the challenges associated with the various techniques, the 31 studies using either functional MRI or PET to image pain processing in rodents have yielded surprisingly consistent results, with brain regions commonly activated in human pain imaging studies (somatosensory cortex, cingulate cortex, thalamus) also being activated in the majority of these studies. Pharmacological imaging in rodents shows overlapping activation patterns with pain and opiate analgesics, similar to what is found in humans. Despite the many structural imaging studies in human chronic pain patients, only one study has been performed in rodents, but that study confirmed human findings of decreased cortical thickness associated with chronic pain. Future directions in rodent pain imaging include miniaturized PET for the freely moving animal, as well as new MRI techniques that enable ongoing chronic pain imaging.
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Affiliation(s)
- Scott J Thompson
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC H3A 2T5, Canada
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Johnston IN, Maier SF, Rudy JW, Watkins LR. Post-conditioning experience with acute or chronic inflammatory pain reduces contextual fear conditioning in the rat. Behav Brain Res 2011; 226:361-8. [PMID: 21920390 DOI: 10.1016/j.bbr.2011.08.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 08/27/2011] [Accepted: 08/31/2011] [Indexed: 11/26/2022]
Abstract
There is evidence that pain can impact cognitive function in people. The present study evaluated whether Pavlovian fear conditioning in rats would be reduced if conditioning were followed by persistent inflammatory pain induced by a subcutaneous injection of dilute formalin or complete Freund's adjuvant (CFA) on the dorsal lumbar surface of the back. Formalin-induced pain specifically impaired contextual fear conditioning but not auditory cue conditioning (Experiment 1A). Moreover, formalin pain only impaired contextual fear conditioning if it was initiated within 1h of conditioning and did not have a significant effect if initiated 2, 8 or 32 h after (Experiments 1A and 1B). Experiment 2 showed that formalin pain initiated after a session of context pre-exposure reduced the ability of that pre-exposure to facilitate contextual fear when the rat was limited to a brief exposure to the context during conditioning. Similar impairments in context- but not CS-fear conditioning were also observed if the rats received an immediate post-conditioning injection with CFA (Experiment 3). Finally, we confirmed that formalin and CFA injected s.c. on the back induced pain-indicative behaviours, hyperalgesia and allodynia with a similar timecourse to intraplantar injections (Experiment 4). These results suggest that persistent pain impairs learning in a hippocampus-dependent task, and may disrupt processes that encode experiences into long-term memory.
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Affiliation(s)
- Ian N Johnston
- School of Psychology, The University of Sydney, NSW 2006, Australia.
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18
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Zhao F, Welsh D, Williams M, Coimbra A, Urban MO, Hargreaves R, Evelhoch J, Williams DS. fMRI of pain processing in the brain: a within-animal comparative study of BOLD vs. CBV and noxious electrical vs. noxious mechanical stimulation in rat. Neuroimage 2011; 59:1168-79. [PMID: 21856430 DOI: 10.1016/j.neuroimage.2011.08.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 07/01/2011] [Accepted: 08/02/2011] [Indexed: 11/19/2022] Open
Abstract
This study aims to identify fMRI signatures of nociceptive processing in whole brain of anesthetized rats during noxious electrical stimulation (NES) and noxious mechanical stimulation (NMS) of paw. Activation patterns for NES were mapped with blood oxygen level dependent (BOLD) and cerebral blood volume (CBV) fMRI, respectively, to investigate the spatially-dependent hemodynamic responses during nociception processing. A systematic evaluation of fMRI responses to varying frequencies of electrical stimulus was carried out to optimize the NES protocol. Both BOLD and CBV fMRI showed widespread activations, but with different spatial characteristics. While BOLD and CBV showed well-localized activations in ipsilateral dorsal column nucleus, contralateral primary somatosensory cortex (S1), and bilateral caudate putamen (CPu), CBV fMRI showed additional bilateral activations in the regions of pons, midbrain and thalamus compared to BOLD fMRI. CBV fMRI that offers higher sensitivity compared to BOLD was then used to compare the nociception processing during NES and NMS in the same animal. The activations in most regions were similar. In the medulla, however, NES induced a robust activation in the ipsilateral dorsal column nucleus while NMS showed no activation. This study demonstrates that (1) the hemodynamic response to nociception is spatial-dependent; (2) the widespread activations during nociception in CBV fMRI are similar to what have been observed in (14)C-2-deoxyglucose (2DG) autoradiography and PET; (3) the bilateral activations in the brain originate from the divergence of neural responses at supraspinal level; and (4) the similarity of activation patterns suggests that nociceptive processing in rats is similar during NES and NMS.
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Affiliation(s)
- Fuqiang Zhao
- Imaging Department, Merck Research Laboratories, West Point, PA 19486, USA.
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Differential roles of ERK, JNK and p38 MAPK in pain-related spatial and temporal enhancement of synaptic responses in the hippocampal formation of rats: Multi-electrode array recordings. Brain Res 2011; 1382:57-69. [DOI: 10.1016/j.brainres.2011.01.076] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/21/2010] [Accepted: 01/24/2011] [Indexed: 12/30/2022]
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Striatal and cortical BOLD, blood flow, blood volume, oxygen consumption, and glucose consumption changes in noxious forepaw electrical stimulation. J Cereb Blood Flow Metab 2011; 31:832-41. [PMID: 20940730 PMCID: PMC3063626 DOI: 10.1038/jcbfm.2010.173] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Recent reports showed noxious forepaw stimulation in rats evoked an unexpected sustained decrease in cerebral blood volume (CBV) in the bilateral striatum, whereas increases in spike activity and Fos-immunoreactive cells were observed. This study aimed to further evaluate the hemodynamic and metabolic needs in this model and the sources of negative functional magnetic resonance imaging (fMRI) signals by measuring blood oxygenation-level-dependent (BOLD), cerebral-blood-flow (CBF), CBV, and oxygen-consumption (i.e., cerebral metabolic rate of oxygen (CMRO(2))) changes using an 11.7-T MRI scanner, and glucose-consumption (i.e., cerebral metabolic rate of glucose (CMRglc)) changes using micro-positron emission tomography. In the contralateral somatosensory cortex, BOLD, CBF, CBV, CMRO(2) (n=7, P<0.05), and CMRglc (n=5, P<0.05) increased. In contrast, in the bilateral striatum, BOLD, CBF, and CBV decreased (P<0.05), CMRO(2) decreased slightly, although not significantly from baseline, and CMRglc was not statistically significant from baseline (P>0.05). These multimodal functional imaging findings corroborate the unexpected negative hemodynamic changes in the striatum during noxious forepaw stimulation, and support the hypothesis that striatal hemodynamic response is dominated by neurotransmitter-mediated vasoconstriction, overriding the stimulus-evoked fMRI signal increases commonly accompany elevated neuronal activity. Multimodal functional imaging approach offers a means to probe the unique attributes of the striatum, providing novel insights into the neurovascular coupling in the striatum. These findings may have strong implications in fMRI studies of pain.
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Involvement of the heme oxygenase-carbon monoxide-cGMP pathway in the nociception induced by acute painful stimulus in rats. Brain Res 2011; 1385:107-13. [PMID: 21349250 DOI: 10.1016/j.brainres.2011.02.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 01/28/2011] [Accepted: 02/14/2011] [Indexed: 11/23/2022]
Abstract
Heme oxygenase-carbon monoxide-cGMP (HO-CO-cGMP) pathway has been reported to be involved in peripheral and spinal modulation of inflammatory pain. However, the involvement of this pathway in the modulation of acute painful stimulus in the absence of inflammation remains unknown. Thus, we evaluated the involvement of the HO-CO-cGMP pathway in nociception by means the of analgesia index (AI) in the tail flick test. Rats underwent surgery for implantation of unilateral guide cannula directed toward the lateral ventricle and after the recovery period (5-7 days) were subjected to the measures of baseline tail flick test. Animals were divided into groups to assess the effect of intracerebroventricular administration (i.c.v.) of the following compounds: ZnDPBG (HO inhibitor) or vehicle (Na(2)CO(3)), heme-lysinate (substrate overload) or vehicle (l-lysine), or the selective inhibitor of soluble guanilate cyclase ODQ or vehicle (DMSO 1%) following the administration of heme-lysinate or vehicle. Heme overload increased AI, indicating an antinociceptive role of the pathway. This response was attenuated by i.c.v. pretreatment with the HO inhibitor ZnDPBG. In addition, this effect was dependent on cGMP activity, since the pretreatment with ODQ blocked the increase in the AI. Because CO produces most of its actions via cGMP, these data strongly imply that CO is the HO product involved in the antinociceptive response. This modulation seems to be phasic rather than tonic, since i.c.v. treatment with ZnDPBG or ODQ did not alter the AI. Therefore, we provide evidence consistent with the notion that HO-CO-cGMP pathway plays a key phasic antinociceptive role modulating noninflammatory acute pain.
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Yang PF, Chen DY, Hu JW, Chen JH, Yen CT. Functional tracing of medial nociceptive pathways using activity-dependent manganese-enhanced MRI. Pain 2011; 152:194-203. [DOI: 10.1016/j.pain.2010.10.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 10/09/2010] [Accepted: 10/20/2010] [Indexed: 11/30/2022]
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Abstract
Pain is a complex experience consisting of sensory-discriminative, affective-motivational, and cognitive-evaluative dimensions. Now it has been gradually known that noxious information is processed by a widely-distributed, hierarchically- interconnected neural network, referred to as neuromatrix, in the brain. Thus, identifying the multiple neural networks subserving these functional aspects and harnessing this knowledge to manipulate the pain response in new and beneficial ways are challenging tasks. Albeit with elaborate research efforts on the cortical responses to painful stimuli or clinical pain, involvement of the hippocampal formation (HF) in pain is still a matter of controversy. Here, we integrate previous animal and human studies from the viewpoint of HF and pain, sequentially representing anatomical, behavioral, electrophysiological, molecular/biochemical and functional imaging evidence supporting the role of HF in pain processing. At last, we further expound on the relationship between pain and memory and present some unresolved issues.
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Affiliation(s)
- Ming-Gang Liu
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing 100069, China
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Central sensitization: a generator of pain hypersensitivity by central neural plasticity. THE JOURNAL OF PAIN 2009; 10:895-926. [PMID: 19712899 DOI: 10.1016/j.jpain.2009.06.012] [Citation(s) in RCA: 2220] [Impact Index Per Article: 148.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 06/08/2009] [Accepted: 06/08/2009] [Indexed: 02/08/2023]
Abstract
UNLABELLED Central sensitization represents an enhancement in the function of neurons and circuits in nociceptive pathways caused by increases in membrane excitability and synaptic efficacy as well as to reduced inhibition and is a manifestation of the remarkable plasticity of the somatosensory nervous system in response to activity, inflammation, and neural injury. The net effect of central sensitization is to recruit previously subthreshold synaptic inputs to nociceptive neurons, generating an increased or augmented action potential output: a state of facilitation, potentiation, augmentation, or amplification. Central sensitization is responsible for many of the temporal, spatial, and threshold changes in pain sensibility in acute and chronic clinical pain settings and exemplifies the fundamental contribution of the central nervous system to the generation of pain hypersensitivity. Because central sensitization results from changes in the properties of neurons in the central nervous system, the pain is no longer coupled, as acute nociceptive pain is, to the presence, intensity, or duration of noxious peripheral stimuli. Instead, central sensitization produces pain hypersensitivity by changing the sensory response elicited by normal inputs, including those that usually evoke innocuous sensations. PERSPECTIVE In this article, we review the major triggers that initiate and maintain central sensitization in healthy individuals in response to nociceptor input and in patients with inflammatory and neuropathic pain, emphasizing the fundamental contribution and multiple mechanisms of synaptic plasticity caused by changes in the density, nature, and properties of ionotropic and metabotropic glutamate receptors.
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Zhao XY, Liu MG, Yuan DL, Wang Y, He Y, Wang DD, Chen XF, Zhang FK, Li H, He XS, Chen J. Nociception-induced spatial and temporal plasticity of synaptic connection and function in the hippocampal formation of rats: a multi-electrode array recording. Mol Pain 2009; 5:55. [PMID: 19772643 PMCID: PMC2759921 DOI: 10.1186/1744-8069-5-55] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 09/22/2009] [Indexed: 12/12/2022] Open
Abstract
Background Pain is known to be processed by a complex neural network (neuromatrix) in the brain. It is hypothesized that under pathological state, persistent or chronic pain can affect various higher brain functions through ascending pathways, leading to co-morbidities or mental disability of pain. However, so far the influences of pathological pain on the higher brain functions are less clear and this may hinder the advances in pain therapy. In the current study, we studied spatiotemporal plasticity of synaptic connection and function in the hippocampal formation (HF) in response to persistent nociception. Results On the hippocampal slices of rats which had suffered from persistent nociception for 2 h by receiving subcutaneous bee venom (BV) or formalin injection into one hand paw, multisite recordings were performed by an 8 × 8 multi-electrode array probe. The waveform of the field excitatory postsynaptic potential (fEPSP), induced by perforant path electrical stimulation and pharmacologically identified as being activity-dependent and mediated by ionotropic glutamate receptors, was consistently positive-going in the dentate gyrus (DG), while that in the CA1 was negative-going in shape in naïve and saline control groups. For the spatial characteristics of synaptic plasticity, BV- or formalin-induced persistent pain significantly increased the number of detectable fEPSP in both DG and CA1 area, implicating enlargement of the synaptic connection size by the injury or acute inflammation. Moreover, the input-output function of synaptic efficacy was shown to be distinctly enhanced by the injury with the stimulus-response curve being moved leftward compared to the control. For the temporal plasticity, long-term potentiation produced by theta burst stimulation (TBS) conditioning was also remarkably enhanced by pain. Moreover, it is strikingly noted that the shape of fEPSP waveform was drastically deformed or split by a TBS conditioning under the condition of persistent nociception, while that in naïve or saline control state was not affected. All these changes in synaptic connection and function, confirmed by the 2-dimentional current source density imaging, were found to be highly correlated with peripheral persistent nociception since pre-blockade of nociceptive impulses could eliminate all of them. Finally, the initial pharmacological investigation showed that AMPA/KA glutamate receptors might play more important roles in mediation of pain-associated spatiotemporal plasticity than NMDA receptors. Conclusion Peripheral persistent nociception produces great impact upon the higher brain structures that lead to not only temporal plasticity, but also spatial plasticity of synaptic connection and function in the HF. The spatial plasticity of synaptic activities is more complex than the temporal plasticity, comprising of enlargement of synaptic connection size at network level, deformed fEPSP at local circuit level and, increased synaptic efficacy at cellular level. In addition, the multi-synaptic model established in the present investigation may open a new avenue for future studies of pain-related brain dysfunctions at the higher level of the neuromatrix.
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Affiliation(s)
- Xiao-Yan Zhao
- Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing, PR China.
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A new scenario for negative functional magnetic resonance imaging signals: endogenous neurotransmission. J Neurosci 2009; 29:3036-44. [PMID: 19279240 DOI: 10.1523/jneurosci.3447-08.2009] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) has revolutionized investigations of brain functions. Increases in fMRI signals are usually correlated with neuronal activation, but diverse explanations have been proposed for negative fMRI responses, including decreases in neuronal activity, the vascular-steal effect, and large increases in oxygen consumption. These possible scenarios, although encompassing a wide range of potential neurovascular responses, cannot yet be used to interpret certain types of negative fMRI signals. Recent studies have found that intravenous injection of dopamine D(2) receptor (D2DR) agonist reduced the hemodynamic responses in the caudate-putamen (CPu); however, whether endogenous dopaminergic neurotransmission contributes to fMRI signals remains obscure. Since it has been suggested that the D2DR is involved in pain modulation, and the CPu shows equivocal fMRI signals during noxious stimulation, the present study established an animal model based on graded electrical stimulation to elicit different levels of nociception, and aimed to determine whether nociception-induced endogenous dopaminergic neurotransmission is sufficient to generate negative fMRI responses. Our results from cerebral blood volume (CBV)-weighted fMRI, Fos immunohistochemistry, and electrophysiological recording demonstrated a salient bilateral CBV decreases associated with heightened neuronal activity in the CPu induced by unilateral noxious electrical stimulation. In addition, preinjection of D2DR antagonist reduced the observed CBV decreases. Our findings reveal the role of the D2DR in regulating striatal vascular responses and suggest that endogenous neurotransmission-induced CBV decreases underlie negative fMRI signals. Hence, the influence of endogenous neurotransmission should be considered when interpreting fMRI data, especially in an area involved in strong vasoactive neurotransmission.
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