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O'Brien JA, Austin PJ. Minocycline Abrogates Individual Differences in Nerve Injury-Evoked Affective Disturbances in Male Rats and Prevents Associated Supraspinal Neuroinflammation. J Neuroimmune Pharmacol 2024; 19:30. [PMID: 38878098 PMCID: PMC11180027 DOI: 10.1007/s11481-024-10132-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 06/08/2024] [Indexed: 06/19/2024]
Abstract
Chronic neuropathic pain precipitates a complex range of affective and behavioural disturbances that differ markedly between individuals. While the reasons for differences in pain-related disability are not well understood, supraspinal neuroimmune interactions are implicated. Minocycline has antidepressant effects in humans and attenuates affective disturbances in rodent models of pain, and acts by reducing neuroinflammation in both the spinal cord and brain. Previous studies, however, tend not to investigate how minocycline modulates individual affective responses to nerve injury, or rely on non-naturalistic behavioural paradigms that fail to capture the complexity of rodent behaviour. We investigated the development and resolution of pain-related affective disturbances in nerve-injured male rats by measuring multiple spontaneous ethological endpoints on a longitudinal naturalistic foraging paradigm, and the effect of chronic oral minocycline administration on these changes. Disrupted foraging behaviours appeared in 22% of nerve-injured rats - termed 'affected' rats - and were present at day 14 but partially resolved by day 21 post-injury. Minocycline completely prevented the emergence of an affected subgroup while only partly attenuating mechanical allodynia, dissociating the relationship between pain and affect. This was associated with a lasting downregulation of ΔFosB expression in ventral hippocampal neurons at day 21 post-injury. Markers of microglia-mediated neuroinflammation were not present by day 21, however proinflammatory microglial polarisation was apparent in the medial prefrontal cortex of affected rats and not in CCI minocycline rats. Individual differences in affective disturbances following nerve injury are therefore temporally related to altered microglial morphology and hippocampal neuronal activation, and are abrogated by minocycline.
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Affiliation(s)
- Jayden A O'Brien
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia
| | - Paul J Austin
- Brain and Mind Centre, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia.
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2
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Emvalomenos GM, Kang JWM, Jupp B, Mychasiuk R, Keay KA, Henderson LA. Recent developments and challenges in positron emission tomography imaging of gliosis in chronic neuropathic pain. Pain 2024:00006396-990000000-00597. [PMID: 38713812 DOI: 10.1097/j.pain.0000000000003247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/05/2024] [Indexed: 05/09/2024]
Abstract
ABSTRACT Understanding the mechanisms that underpin the transition from acute to chronic pain is critical for the development of more effective and targeted treatments. There is growing interest in the contribution of glial cells to this process, with cross-sectional preclinical studies demonstrating specific changes in these cell types capturing targeted timepoints from the acute phase and the chronic phase. In vivo longitudinal assessment of the development and evolution of these changes in experimental animals and humans has presented a significant challenge. Recent technological advances in preclinical and clinical positron emission tomography, including the development of specific radiotracers for gliosis, offer great promise for the field. These advances now permit tracking of glial changes over time and provide the ability to relate these changes to pain-relevant symptomology, comorbid psychiatric conditions, and treatment outcomes at both a group and an individual level. In this article, we summarize evidence for gliosis in the transition from acute to chronic pain and provide an overview of the specific radiotracers available to measure this process, highlighting their potential, particularly when combined with ex vivo/in vitro techniques, to understand the pathophysiology of chronic neuropathic pain. These complementary investigations can be used to bridge the existing gap in the field concerning the contribution of gliosis to neuropathic pain and identify potential targets for interventions.
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Affiliation(s)
- Gaelle M Emvalomenos
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - James W M Kang
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Bianca Jupp
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Kevin A Keay
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Luke A Henderson
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
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3
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Mussetto V, Moen A, Trofimova L, Sandkühler J, Hogri R. Differential activation of spinal and parabrachial glial cells in a neuropathic pain model. Front Cell Neurosci 2023; 17:1163171. [PMID: 37082205 PMCID: PMC10110840 DOI: 10.3389/fncel.2023.1163171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 03/17/2023] [Indexed: 04/22/2023] Open
Abstract
The clinical burden faced by chronic pain patients is compounded by affective comorbidities, such as depression and anxiety disorders. Emerging evidence suggests that reactive glial cells in the spinal cord dorsal horn play a key role in the chronification of pain, while supraspinal glia are important for psychological aspects of chronic pain. The lateral parabrachial nucleus (LPBN) in the brainstem is a key node in the ascending pain system, and is crucial for the emotional dimension of pain. Yet, whether astrocytes and microglia in the LPBN are activated during chronic pain is unknown. Here, we evaluated the occurrence of glial activation in the LPBN of male Sprague-Dawley rats 1, 4, and 7 weeks after inducing a chronic constriction injury (CCI) of the sciatic nerve, a prevalent neuropathic pain model. CCI animals developed mechanical and thermal hypersensitivity that persisted for at least 4 weeks, and was mostly reversed after 7 weeks. Using immunohistochemical staining and confocal imaging, we found that CCI caused a strong increase in the expression of the astrocytic marker GFAP and the microglial marker Iba1 in the ipsilateral spinal dorsal horn, with peak expression observed 1 week post-injury. Moreover, morphology analysis revealed changes in microglial phenotype, indicative of microglia activation. In contrast, CCI did not induce any detectable changes in either astrocytes or microglia in the LPBN, at any time point. Thus, our results indicate that while neuropathic pain induces a robust glial reaction in the spinal dorsal horn, it fails to activate glial cells in the LPBN.
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Affiliation(s)
| | | | | | | | - Roni Hogri
- Department of Neurophysiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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4
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Malange KF, Navia-Pelaez JM, Dias EV, Lemes JBP, Choi SH, Dos Santos GG, Yaksh TL, Corr M. Macrophages and glial cells: Innate immune drivers of inflammatory arthritic pain perception from peripheral joints to the central nervous system. FRONTIERS IN PAIN RESEARCH 2022; 3:1018800. [PMID: 36387416 PMCID: PMC9644179 DOI: 10.3389/fpain.2022.1018800] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 10/03/2022] [Indexed: 07/22/2023] Open
Abstract
Millions of people suffer from arthritis worldwide, consistently struggling with daily activities due to debilitating pain evoked by this disease. Perhaps the most intensively investigated type of inflammatory arthritis is rheumatoid arthritis (RA), where, despite considerable advances in research and clinical management, gaps regarding the neuroimmune interactions that guide inflammation and chronic pain in this disease remain to be clarified. The pain and inflammation associated with arthritis are not isolated to the joints, and inflammatory mechanisms induced by different immune and glial cells in other tissues may affect the development of chronic pain that results from the disease. This review aims to provide an overview of the state-of-the-art research on the roles that innate immune, and glial cells play in the onset and maintenance of arthritis-associated pain, reviewing nociceptive pathways from the joint through the dorsal root ganglion, spinal circuits, and different structures in the brain. We will focus on the cellular mechanisms related to neuroinflammation and pain, and treatments targeting these mechanisms from the periphery and the CNS. A comprehensive understanding of the role these cells play in peripheral inflammation and initiation of pain and the central pathways in the spinal cord and brain will facilitate identifying new targets and pathways to aide in developing therapeutic strategies to treat joint pain associated with RA.
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Affiliation(s)
- Kaue Franco Malange
- Department of Anesthesiology, University of California, San Diego, CA, United States
| | | | - Elayne Vieira Dias
- Department of Neurology, University of California, San Francisco, CA, United States
| | | | - Soo-Ho Choi
- Department of Medicine, University of California, San Diego, CA, United States
| | | | - Tony L. Yaksh
- Department of Anesthesiology, University of California, San Diego, CA, United States
| | - Maripat Corr
- Department of Medicine, University of California, San Diego, CA, United States
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5
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Boorman DC, Keay KA. Sex differences in morphine sensitivity are associated with differential glial expression in the brainstem of rats with neuropathic pain. J Neurosci Res 2022; 100:1890-1907. [PMID: 35853016 PMCID: PMC9543783 DOI: 10.1002/jnr.25103] [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: 03/15/2022] [Revised: 06/20/2022] [Accepted: 06/22/2022] [Indexed: 11/11/2022]
Abstract
Chronic pain is more prevalent and reported to be more severe in women. Opioid analgesics are less effective in women and result in stronger nauseant effects. The neurobiological mechanisms underlying these sex differences have yet to be clearly defined, though recent research has suggested neuronal–glial interactions are likely involved. We have previously shown that similar to people, morphine is less effective at reducing pain behaviors in female rats. In this study, we used the immunohistochemical detection of glial fibrillary acidic protein (GFAP) expression to investigate sex differences in astrocyte density and morphology in six medullary regions known to be modulated by pain and/or opioids. Morphine administration had small sex‐dependent effects on overall GFAP expression, but not on astrocyte morphology, in the rostral ventromedial medulla, the subnucleus reticularis dorsalis, and the area postrema. Significant sex differences in the density and morphology of GFAP immunopositive astrocytes were detected in all six regions. In general, GFAP‐positive cells in females showed smaller volumes and reduced complexity than those observed in males. Furthermore, females showed lower overall GFAP expression in all regions except for the area postrema, the critical medullary region responsible for opioid‐induced nausea and emesis. These data support the possibility that differences in astrocyte activity might underlie the sex differences seen in the processing of opioids in the context of chronic neuropathic pain.
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Affiliation(s)
- Damien C. Boorman
- School of Medical Sciences and the Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
| | - Kevin A. Keay
- School of Medical Sciences and the Brain and Mind Centre The University of Sydney Camperdown New South Wales Australia
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6
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Sosa MK, Boorman DC, Keay KA. Sciatic nerve injury rebalances the hypothalamic-pituitary-adrenal axis in rats with persistent changes to their social behaviours. J Neuroendocrinol 2022; 34:e13131. [PMID: 35487591 PMCID: PMC9286784 DOI: 10.1111/jne.13131] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/31/2022] [Accepted: 03/24/2022] [Indexed: 11/29/2022]
Abstract
Increased glucocorticoids characterise acute pain responses, but not the chronic pain state, suggesting specific modifications to the hypothalamic-pituitary-adrenal (HPA)-axis preventing the persistent nature of chronic pain from elevating basal glucocorticoid levels. Individuals with chronic pain mount normal HPA-axis responses to acute stressors, indicating a rebalancing of the circuits underpinning these responses. Preclinical models of chronic neuropathic pain generally recapitulate these clinical observations, but few studies have considered that the underlying neuroendocrine circuitry may be altered. Additionally, individual differences in the behavioural outcomes of these pain models, which are strikingly similar to the range of behavioural subpopulations that manifest in response to stress, threat and motivational cues, may also be reflected in divergent patterns of HPA-axis activity, which characterises these other behavioural subpopulations. We investigated the effects of sciatic nerve chronic constriction injury (CCI) on adrenocortical and hypothalamic markers of HPA-axis activity in the subpopulation of rats showing persistent changes in social interactions after CCI (Persistent Effect) and compared them with rats that do not show these changes (No Effect). Basal plasma corticosterone did not change after CCI and did not differ between groups. However, adrenocortical sensitivity to adrenocorticotropic hormone (ACTH) diverged between these groups. No Effect rats showed large increases in basal plasma ACTH with no change in adrenocortical melanocortin 2 receptor (MC2 R) expression, whereas Persistent Effect rats showed modest decreases in plasma ACTH and large increases in MC2 R expression. In the paraventricular nucleus of the hypothalamus of Persistent Effect rats, single labelling revealed significantly increased numbers of corticotropin releasing factor (CRF) +ve and glucocorticoid receptor (GR) +ve neurons. Double-labelling revealed fewer GR +ve CRF +ve neurons, suggesting a decreased hypothalamic sensitivity of CRF neurons to circulating corticosterone in Persistent Effect rats. We suggest that in addition to rebalancing the HPA-axis, the increased CRF expression in Persistent Effect rats contributes to changes in complex behaviours, and in particular social interactions.
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Affiliation(s)
- M. Karmina Sosa
- School of Medical Sciences and the Brain and Mind CentreThe University of SydneyCamperdownNew South WalesAustralia
| | - Damien C. Boorman
- School of Medical Sciences and the Brain and Mind CentreThe University of SydneyCamperdownNew South WalesAustralia
| | - Kevin A. Keay
- School of Medical Sciences and the Brain and Mind CentreThe University of SydneyCamperdownNew South WalesAustralia
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7
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Fiore NT, Yin Z, Guneykaya D, Gauthier CD, Hayes J, D’hary A, Butovsky O, Moalem-Taylor G. Sex-specific transcriptome of spinal microglia in neuropathic pain due to peripheral nerve injury. Glia 2022; 70:675-696. [PMID: 35050555 PMCID: PMC8852349 DOI: 10.1002/glia.24133] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/13/2022]
Abstract
Neuropathic pain is a prevalent and debilitating chronic disease that is characterized by activation in glial cells in various pain-related regions within the central nervous system. Recent studies have suggested a sexually dimorphic role of microglia in the maintenance of neuropathic pain in rodents. Here, we utilized RNA sequencing analysis and in vitro primary cultures of microglia to identify whether there is a common neuropathic microglial signature and characterize the sex differences in microglia in pain-related regions in nerve injury and chemotherapy-induced peripheral neuropathy mouse models. While mechanical allodynia and behavioral changes were observed in all models, transcriptomic analysis of microglia revealed no common transcriptional changes in spinal and supraspinal regions and in the different neuropathic models. However, there was a substantial change in microglial gene expression within the ipsilateral lumbar spinal cord 7 days after chronic constriction injury (CCI) of the sciatic nerve. Both sexes upregulated genes associated with inflammation, phagosome, and lysosome activation, though males revealed a prominent global transcriptional shift not observed in female mice. Transcriptomic comparison between male spinal microglia after CCI and data from other nerve injury models and neurodegenerative microglia demonstrated a unique CCI-induced signature reflecting acute activation of microglia. Further, in vitro studies revealed that only male microglia from nerve-injured mice developed a reactive phenotype with increased phagocytotic activity. This study demonstrates a lack of a common neuropathic microglial signature and indicates distinct sex differences in spinal microglia, suggesting they contribute to the sex-specific pain processing following nerve injury.
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Affiliation(s)
- Nathan T Fiore
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Zhuoran Yin
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Dilansu Guneykaya
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Christian D Gauthier
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Jessica Hayes
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Aaron D’hary
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Oleg Butovsky
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA,Evergrande Center for Immunologic Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Gila Moalem-Taylor
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia,Correspondence: A/Prof. Gila Moalem-Taylor, Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, Wallace Wurth Building, Level 3, room 355B, The University of New South Wales, UNSW Sydney, NSW, 2052, Australia, +61-2-90658014,
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8
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Abstract
Tensioning techniqueswere the first neurodynamic techniques used therapeutically in the management of people with neuropathies. This article aims to provide a balanced evidence-informed view on the effects of optimal tensile loading on peripheral nerves and the use of tensioning techniques. Whilst the early use of neurodynamics was centered within a mechanical paradigm, research into the working mechanisms of tensioning techniques revealed neuroimmune, neurophysiological, and neurochemical effects. In-vitro and ex-vivo research confirms that tensile loading is required for mechanical adaptation of healthy and healing neurons and nerves. Moreover, elimination of tensile load can have detrimental effects on the nervous system. Beneficial effects of tensile loading and tensioning techniques, contributing to restored homeostasis at the entrapment site, dorsal root ganglia and spinal cord, include neuronal cell differentiation, neurite outgrowth and orientation, increased endogenous opioid receptors, reduced fibrosis and intraneural scar formation, improved nerve regeneration and remyelination, increased muscle power and locomotion, less mechanical and thermal hyperalgesia and allodynia, and improved conditioned pain modulation. However, animal and cellular models also show that ‘excessive’ tensile forces have negative effects on the nervous system. Although robust and designed to withstand mechanical load, the nervous system is equally a delicate system. Mechanical loads that can be easily handled by a healthy nervous system, may be sufficient to aggravate clinical symptoms in patients. This paper aims to contribute to a more balanced view regarding the use of neurodynamics and more specifically tensioning techniques.
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Affiliation(s)
- Richard Ellis
- School of Clinical Sciences, Active Living and Rehabilitation: Aotearoa, Health and Rehabilitation Research Institute, Auckland University of Technology, Auckland, New Zealand.,Department of Physiotherapy, School of Clinical Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Giacomo Carta
- Department of Clinical and Biological Sciences, University of Torino, Orbassano, Italy.,Neuroscience Institute Cavalieri Ottolenghi (Nico), University of Torino, Orbassano, Italy.,ASST Nord Milano, Sesto San Giovanni Hospital, Milan, Italy
| | - Ricardo J Andrade
- Menzies Health Institute Queensland, Griffith University, Brisbane and Gold Coast, Australia.,School of Health Sciences and Social Work, Griffith University, Queensland, USA
| | - Michel W Coppieters
- Menzies Health Institute Queensland, Griffith University, Brisbane and Gold Coast, Australia.,Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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9
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Mills EP, Keay KA, Henderson LA. Brainstem Pain-Modulation Circuitry and Its Plasticity in Neuropathic Pain: Insights From Human Brain Imaging Investigations. FRONTIERS IN PAIN RESEARCH 2021; 2:705345. [PMID: 35295481 PMCID: PMC8915745 DOI: 10.3389/fpain.2021.705345] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/23/2021] [Indexed: 11/17/2022] Open
Abstract
Acute pain serves as a protective mechanism that alerts us to potential tissue damage and drives a behavioural response that removes us from danger. The neural circuitry critical for mounting this behavioural response is situated within the brainstem and is also crucial for producing analgesic and hyperalgesic responses. In particular, the periaqueductal grey, rostral ventromedial medulla, locus coeruleus and subnucleus reticularis dorsalis are important structures that directly or indirectly modulate nociceptive transmission at the primary nociceptive synapse. Substantial evidence from experimental animal studies suggests that plasticity within this system contributes to the initiation and/or maintenance of chronic neuropathic pain, and may even predispose individuals to developing chronic pain. Indeed, overwhelming evidence indicates that plasticity within this circuitry favours pro-nociception at the primary synapse in neuropathic pain conditions, a process that ultimately contributes to a hyperalgesic state. Although experimental animal investigations have been crucial in our understanding of the anatomy and function of the brainstem pain-modulation circuitry, it is vital to understand this system in acute and chronic pain states in humans so that more effective treatments can be developed. Recent functional MRI studies have identified a key role of this system during various analgesic and hyperalgesic responses including placebo analgesia, offset analgesia, attentional analgesia, conditioned pain modulation, central sensitisation and temporal summation. Moreover, recent MRI investigations have begun to explore brainstem pain-modulation circuitry plasticity in chronic neuropathic pain conditions and have identified altered grey matter volumes and functioning throughout the circuitry. Considering the findings from animal investigations, it is likely that these changes reflect a shift towards pro-nociception that ultimately contributes to the maintenance of neuropathic pain. The purpose of this review is to provide an overview of the human brain imaging investigations that have improved our understanding of the pain-modulation system in acute pain states and in neuropathic conditions. Our interpretation of the findings from these studies is often guided by the existing body of experimental animal literature, in addition to evidence from psychophysical investigations. Overall, understanding the plasticity of this system in human neuropathic pain conditions alongside the existing experimental animal literature will ultimately improve treatment options.
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10
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Keay KA, Argueta MA, Zafir DN, Wyllie PM, Michael GJ, Boorman DC. Evidence that increased cholecystokinin (CCK) in the periaqueductal gray (PAG) facilitates changes in Resident-Intruder social interactions triggered by peripheral nerve injury. J Neurochem 2021; 158:1151-1171. [PMID: 34287873 DOI: 10.1111/jnc.15476] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/26/2022]
Abstract
Individual differences in the effects of a chronic neuropathic injury on social behaviours characterize both the human experience and pre-clinical animal models. The impacts of these changes to the well-being of the individual are often underappreciated. Earlier work from our laboratory using GeneChip® microarrays identified increased cholecystokinin (CCK) gene expression in the periaqueductal gray (PAG) of rats that showed persistent changes in social interactions during a Resident-Intruder encounter following sciatic nerve chronic constriction injury (CCI). In this study, we confirmed these gene regulation patterns using RT-PCR and identified the anatomical location of the CCK-mRNA as well as the translated CCK peptides in the midbrains of rats with a CCI. We found that rats with persistent CCI-induced changes in social behaviours had increased CCK-mRNA in neurons of the ventrolateral PAG and dorsal raphe nuclei, as well as increased CCK-8 peptide expression in terminal boutons located in the lateral and ventrolateral PAG. The functional significance of these changes was explored by microinjecting small volumes of CCK-8 into the PAG of uninjured rats and observing their Resident-Intruder social interactions. Disturbances to social interactions identical to those observed in CCI rats were evoked when injection sites were located in the rostral lateral and ventrolateral PAG. We suggest that CCI-induced changes in CCK expression in these PAG regions contributes to the disruptions to social behaviours experienced by a subset of individuals with neuropathic injury.
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Affiliation(s)
- Kevin A Keay
- School of Medical Sciences and the Brain and Mind Centre, The University of Sydney, New South Wales, Australia
| | - Manuel A Argueta
- School of Medical Sciences and the Brain and Mind Centre, The University of Sydney, New South Wales, Australia
| | - Daniel N Zafir
- School of Medical Sciences and the Brain and Mind Centre, The University of Sydney, New South Wales, Australia
| | - Peter M Wyllie
- School of Medical Sciences and the Brain and Mind Centre, The University of Sydney, New South Wales, Australia
| | - Gregory J Michael
- Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Damien C Boorman
- School of Medical Sciences and the Brain and Mind Centre, The University of Sydney, New South Wales, Australia
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11
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Tang J, Bair M, Descalzi G. Reactive Astrocytes: Critical Players in the Development of Chronic Pain. Front Psychiatry 2021; 12:682056. [PMID: 34122194 PMCID: PMC8192827 DOI: 10.3389/fpsyt.2021.682056] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 05/03/2021] [Indexed: 12/16/2022] Open
Abstract
Chronic pain is associated with long term plasticity of nociceptive pathways in the central nervous system. Astrocytes can profoundly affect synaptic function and increasing evidence has highlighted how altered astrocyte activity may contribute to the pathogenesis of chronic pain. In response to injury, astrocytes undergo a shift in form and function known as reactive astrogliosis, which affects their release of cytokines and gliotransmitters. These neuromodulatory substances have been implicated in driving the persistent changes in central nociceptive activity. Astrocytes also release lactate which neurons can use to produce energy during synaptic plasticity. Furthermore, recent research has provided insight into lactate's emerging role as a signaling molecule in the central nervous system, which may be involved in directly modulating neuronal and astrocytic activity. In this review, we present evidence for the involvement of astrocyte-derived tumor necrosis factor alpha in pain-associated plasticity, in addition to research suggesting the potential involvement of gliotransmitters D-serine and adenosine-5'-triphosphate. We also discuss work implicating astrocyte-neuron metabolic coupling, and the possible role of lactate, which has been sparsely studied in the context of chronic pain, in supporting pathological changes in central nociceptive activity.
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Affiliation(s)
| | | | - Giannina Descalzi
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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12
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Gao W, Wang Z, Wang H, Li H, Huang C, Shen Y, Ma X, Sun H. Neurons and Astrocytes in Ventrolateral Periaqueductal Gray Contribute to Restraint Water Immersion Stress-Induced Gastric Mucosal Damage via the ERK1/2 Signaling Pathway. Int J Neuropsychopharmacol 2021; 24:666-676. [PMID: 34000028 PMCID: PMC8378083 DOI: 10.1093/ijnp/pyab028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 03/15/2021] [Accepted: 05/12/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The restraint water immersion stress (RWIS) model includes both psychological and physical stimulation, which may lead to gastrointestinal disorders and cause gastric mucosal damage. The ventrolateral periaqueductal gray (VLPAG) contributes to gastrointestinal function, but whether it is involved in RWIS-induced gastric mucosal damage has not yet been reported. METHODS The expression of glial fibrillary acidic protein, neuronal c-Fos, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG after RWIS was assessed using western blotting and immunocytochemical staining methods. Lateral ventricle injection of astrocytic toxin L-a-aminoadipate and treatment with extracellular signal-regulated kinase (ERK)1/2 signaling pathway inhibitor PD98059 were further used to study protein expression and distribution in the VLPAG after RWIS. RESULTS The expression of c-Fos, glial fibrillary acidic protein, and phosphorylated extracellular signal regulated kinase 1/2 in the VLPAG significantly increased following RWIS and peaked at 1 hour after RWIS. Lateral ventricle injection of the astrocytic toxin L-a-aminoadipate significantly alleviated gastric mucosal injury and decreased the activation of neurons and astrocytes. Treatment with the ERK1/2 signaling pathway inhibitor PD98059 obviously suppressed gastric mucosal damage as well as the RWIS-induced activation of neurons and astrocytes in the VLPAG. CONCLUSIONS These results suggested that activation of VLPAG neurons and astrocytes induced by RWIS through the ERK1/2 signaling pathway may play a critical role in RWIS-induced gastric mucosa damage.
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Affiliation(s)
- Wenting Gao
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Zepeng Wang
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Hui Wang
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Huimin Li
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Chenxu Huang
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Yangyang Shen
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China
| | - Xiaoli Ma
- Research Center of Basic Medicine, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China,Correspondence: Xiaoli Ma, PhD, Jinan Central Hospital, Cheeloo College of Medicine, Shandong University ()
| | - Haiji Sun
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Science, Shandong Normal University, Jinan, China,Haiji Sun, PhD, College of Life Science, Shandong Normal University ()
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13
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Hwang SN, Lee JS, Seo K, Lee H. Astrocytic Regulation of Neural Circuits Underlying Behaviors. Cells 2021; 10:cells10020296. [PMID: 33535587 PMCID: PMC7912785 DOI: 10.3390/cells10020296] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/23/2021] [Accepted: 01/29/2021] [Indexed: 02/07/2023] Open
Abstract
Astrocytes, characterized by a satellite-like morphology, are the most abundant type of glia in the central nervous system. Their main functions have been thought to be limited to providing homeostatic support for neurons, but recent studies have revealed that astrocytes actually actively interact with local neural circuits and play a crucial role in information processing and generating physiological and behavioral responses. Here, we review the emerging roles of astrocytes in many brain regions, particularly by focusing on intracellular changes in astrocytes and their interactions with neurons at the molecular and neural circuit levels.
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Affiliation(s)
- Sun-Nyoung Hwang
- Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
| | - Jae Seung Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
| | - Kain Seo
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
| | - Hyosang Lee
- Convergence Research Advanced Centre for Olfaction, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Korea;
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea; (J.S.L.); (K.S.)
- Korea Brain Research Institute (KBRI), Daegu 41062, Korea
- Correspondence: ; Tel.: +82-53-785-6147
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14
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Chronic pain impact on rodents’ behavioral repertoire. Neurosci Biobehav Rev 2020; 119:101-127. [DOI: 10.1016/j.neubiorev.2020.09.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 07/14/2020] [Accepted: 09/21/2020] [Indexed: 12/20/2022]
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15
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Austin PJ, Fiore NT. Supraspinal neuroimmune crosstalk in chronic pain states. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Ni HD, Xu LS, Wang Y, Li H, An K, Liu M, Liu Q, Deng H, He Q, Huang B, Fang J, Yao M. Astrocyte activation in the periaqueductal gray promotes descending facilitation to cancer-induced bone pain through the JNK MAPK signaling pathway. Mol Pain 2019; 15:1744806919831909. [PMID: 30700204 PMCID: PMC6388461 DOI: 10.1177/1744806919831909] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Descending nociceptive modulation from the supraspinal structures has an important role in cancer-induced bone pain (CIBP). Midbrain ventrolateral periaqueductal gray (vlPAG) is a critical component of descending nociceptive circuits; nevertheless, its precise cellular and molecular mechanisms involved in descending facilitation remain elusive. Our previous study has shown that the activation of p38 MAPK in vlPAG microglia is essential for the neuropathic pain sensitization. However, the existence of potential connection between astrocytes and c-Jun N-terminal kinase (JNK) pathway in CIBP has not yet been elucidated. The following study examines the involvement of astrocyte activation and upregulation of p-JNK in vlPAG, using a CIBP rat model. Briefly, CIBP was mimicked by an intramedullary injection of Walker 256 mammary gland carcinoma cells into the animal tibia. A significant increase in expression levels of astrocytes in the vlPAG of CIBP rats was observed. Furthermore, stereotaxic microinjection of the astrocytic cytotoxin L-α-aminoadipic acid decreased the mechanical allodynia as well as established and reversed the astrocyte activation in CIBP rats. A significant increase in expression levels of p-JNK in astrocytes in vlPAG of CIBP rats was also observed. Moreover, the intrathecal administration of JNK inhibitors SP600125 reduced the expression of glial fibrillary acidic protein, while microinjection of the SP600125 decreased the mechanical allodynia of CIBP rats. These results suggested that CIBP is associated with astrocyte activation in the vlPAG that probably participates in driving descending pain facilitation through the JNK MAPK signaling pathway. To sum up, these findings reveal a novel site of astrocytes modulation of CIBP.
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Affiliation(s)
- Hua-Dong Ni
- 1 The Second Clinical Medical College, Zhejiang Chinese Medicine University, Hangzhou, China.,2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Long Sheng Xu
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Yungong Wang
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Hongbo Li
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Kang An
- 3 Department of Anesthesiology, Bengbu Medical College, Bengbu, China
| | - Mingjuan Liu
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Qianying Liu
- 3 Department of Anesthesiology, Bengbu Medical College, Bengbu, China
| | - Houshen Deng
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Qiuli He
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Bing Huang
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Jianqiao Fang
- 1 The Second Clinical Medical College, Zhejiang Chinese Medicine University, Hangzhou, China
| | - Ming Yao
- 2 Department of Anesthesiology and Pain Research Center, The First Affiliated Hospital of Jiaxing University, Jiaxing, China
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17
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Castorina A, Vogiatzis M, Kang JWM, Keay KA. PACAP and VIP expression in the periaqueductal grey of the rat following sciatic nerve constriction injury. Neuropeptides 2019; 74:60-69. [PMID: 30579677 DOI: 10.1016/j.npep.2018.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 12/13/2018] [Accepted: 12/13/2018] [Indexed: 11/24/2022]
Abstract
Nerve injuries often result in neuropathic pain with co-morbid changes in social behaviours, motivation, sleep-wake cycles and neuroendocrine function. In an animal model of neuropathic injury (CCI) similar co-morbid changes are evoked in a subpopulation (~30%) of injured rats. In addition to anatomical evidence of altered neuronal and glial function, the periaqueductal grey (PAG) of these rats shows evidence of cell death. These changes in the PAG may play a role in the disruption of the normal emotional coping responses triggered by nerve injury. Cell death can occur via a number of mechanisms, including the disruption of neuroprotective mechanisms. Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two endogenous neuropeptides whose activities are tightly regulated by two receptors subtypes, namely the PAC1 and VPAC receptors. These peptides and their receptors exert robust neuroprotective roles. In these studies, we hypothesized that rats expressing disabilities following CCI showed altered expression of PACAP and VIP in the PAG. Rats were categorized as having either Pain alone, Transient or Persistent disability, based on changes in social behaviours pre- and post-CCI. Social interaction behavioural tested (BT), sham-injured and naïve untested rats were also included. For measurements of mRNA and protein expression we utilised micro-dissected PAGs blocks taken from each group. At the mRNA level, VIP was downregulated and PAC1 was upregulated in BT animals, whilst VPAC1 mRNA was specifically increased in the Pain alone group. Interestingly, protein levels of both PACAP and VIP were remarkably increased in the Persistent Disability group. Taken together, sciatic nerve CCI that triggers neuropathic pain and persistent disability results in abnormally increased VIP and PACAP expression in the PAG. Our data also suggest that these effects are likely to be governed by post-transcriptional mechanisms.
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Affiliation(s)
- Alessandro Castorina
- School of Medical Sciences (Anatomy and Histology), The University of Sydney, Sydney, NSW 2006, Australia.
| | - Monica Vogiatzis
- School of Medical Sciences (Anatomy and Histology), The University of Sydney, Sydney, NSW 2006, Australia
| | - James W M Kang
- School of Medical Sciences (Anatomy and Histology), The University of Sydney, Sydney, NSW 2006, Australia
| | - Kevin A Keay
- School of Medical Sciences (Anatomy and Histology), The University of Sydney, Sydney, NSW 2006, Australia
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18
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Ni H, Wang Y, An K, Liu Q, Xu L, Zhu C, Deng H, He Q, Wang T, Xu M, Zheng Y, Huang B, Fang J, Yao M. Crosstalk between NFκB-dependent astrocytic CXCL1 and neuron CXCR2 plays a role in descending pain facilitation. J Neuroinflammation 2019; 16:1. [PMID: 30606213 PMCID: PMC6317220 DOI: 10.1186/s12974-018-1391-2] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 12/17/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Despite accumulating evidence on the role of glial cells and their associated chemicals in mechanisms of pain, few studies have addressed the potential role of chemokines in the descending facilitation of chronic pain. We aimed to study the hypothesis that CXCL1/CXCR2 axis in the periaqueductal gray (PAG), a co-restructure of the descending nociceptive system, is involved in descending pain facilitation. METHODS Intramedullary injection of Walker 256 mammary gland carcinoma cells of adult female Sprague Dawley rats was used to establish a bone cancer pain (BCP) model. RT-PCR, Western blot, and immunohistochemistry were performed to detect pNfkb, Cxcl1, and Cxcr2 and their protein expression in the ventrolateral PAG (vlPAG). Immunohistochemical co-staining with NeuN, GFAP, and CD11 were used to examine the cellular location of pNFκB, CXCL1, and CXCR2. The effects of NFκB and CXCR2 antagonists and CXCL1 neutralizing antibody on pain hypersensitivity were evaluated by behavioral testing. RESULTS BCP induced cortical bone damage and persistent mechanical allodynia and increased the expression of pNFκB, CXCL1, and CXCR2 in vlPAG. The induced phosphorylation of NFκB was co-localized with GFAP and NeuN, but not with CD11. Micro-injection of BAY11-7082 attenuated BCP and reduced CXCL1 increase in the spinal cord. The expression level of CXCL1 in vlPAG showed co-localization with GFAP, but not with CD11 and NeuN. Micro-administration of CXCL1 neutralizing antibody from 6 to 9 days after inoculation attenuated mechanical allodynia. Furthermore, vlPAG application of CXCL1 elicited pain hypersensitivity in normal rats. Interestingly, CXCR2 was upregulated in vlPAG neurons (not with CD11 and GFAP) after BCP. CXCR2 antagonist SB225002 completely blocked the CXCL1-induced mechanical allodynia and attenuated BCP-induced pain hypersensitivity. CONCLUSION The NFκB-dependent CXCL1-CXCR2 signaling cascade played a role in glial-neuron interactions and in descending facilitation of BCP.
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Affiliation(s)
- Huadong Ni
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Yungong Wang
- Department of Anesthesiology, Zhuzhou Central Hospital, Zhuzhou, 412000 China
| | - Kang An
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, 210004 China
| | - Qianying Liu
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Longsheng Xu
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Chunyan Zhu
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Housheng Deng
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Qiuli He
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Tingting Wang
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Miao Xu
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Ying Zheng
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Bing Huang
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
| | - Jianqiao Fang
- Zhejiang Chinese Medicine University, Hangzhou, 310053 China
| | - Ming Yao
- Department of Anesthesiology and Pain Research center, The First Affiliated Hospital of Jiaxing University, Jiaxing, 314001 China
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19
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Guimarães MR, Soares AR, Cunha AM, Esteves M, Borges S, Magalhães R, Moreira PS, Rodrigues AJ, Sousa N, Almeida A, Leite‐Almeida H. Evidence for lack of direct causality between pain and affective disturbances in a rat peripheral neuropathy model. GENES BRAIN AND BEHAVIOR 2018; 18:e12542. [DOI: 10.1111/gbb.12542] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/22/2018] [Accepted: 11/26/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Marco R. Guimarães
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Ana R. Soares
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Ana M. Cunha
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Madalena Esteves
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Sónia Borges
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Ricardo Magalhães
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
- Clinical Academic Center – Braga Braga Portugal
| | - Pedro S. Moreira
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
- Clinical Academic Center – Braga Braga Portugal
| | - Ana J. Rodrigues
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
- Clinical Academic Center – Braga Braga Portugal
| | - Armando Almeida
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
| | - Hugo Leite‐Almeida
- Life and Health Sciences Research Institute, School of Health Sciences University of Minho Braga Portugal
- ICVS/3B's – PT Government Associate Laboratory Braga Portugal
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20
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Henderson LA. Trigeminal neuropathic pain: Evidence of central changes from human brain imaging investigations. AUST ENDOD J 2018. [DOI: 10.1111/aej.12250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Luke A. Henderson
- Department of Anatomy and Histology; University of Sydney; Sydney New South Wales Australia
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21
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Waschek JA, Baca SM, Akerman S. PACAP and migraine headache: immunomodulation of neural circuits in autonomic ganglia and brain parenchyma. J Headache Pain 2018. [PMID: 29536279 PMCID: PMC5849772 DOI: 10.1186/s10194-018-0850-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The discovery that intravenous (IV) infusions of the neuropeptide PACAP-38 (pituitary adenylyl cyclase activating peptide-38) induced delayed migraine-like headaches in a large majority of migraine patients has resulted in considerable excitement in headache research. In addition to suggesting potential therapeutic targets for migraine, the finding provides an opportunity to better understand the pathological events from early events (aura) to the headache itself. Although PACAP-38 and the closely related peptide VIP (vasoactive intestinal peptide) are well-known as vasoactive molecules, the dilation of cranial blood vessels per se is no longer felt to underlie migraine headaches. Thus, more recent research has focused on other possible PACAP-mediated mechanisms, and has raised some important questions. For example, (1) are endogenous sources of PACAP (or VIP) involved in the triggering and/or propagation of migraine headaches?; (2) which receptor subtypes are involved in migraine pathophysiology?; (3) can we identify specific anatomical circuit(s) where PACAP signaling is involved in the features of migraine? The purpose of this review is to discuss the possibility, and supportive evidence, that PACAP acts to induce migraine-like symptoms not only by directly modulating nociceptive neural circuits, but also by indirectly regulating the production of inflammatory mediators. We focus here primarily on postulated extra-dural sites because potential mechanisms of PACAP action in the dura are discussed in detail elsewhere (see X, this edition).
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Affiliation(s)
- James A Waschek
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA.
| | - Serapio M Baca
- Department of Pharmacy and Pharmaceutical Sciences, University of Colorado, Anschutz Medical Campus, Aurora, CO, 80045, USA.
| | - Simon Akerman
- Department of Oral and Maxillofacial Pathology, Radiology and Medicine, New York University College of Dentistry, New York, NY, 10010, USA. .,Department of Neural and Pain Sciences, University of Maryland Baltimore, Maryland, Baltimore, MD, 21201, USA.
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22
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Dubový P, Klusáková I, Hradilová-Svíženská I, Joukal M, Boadas-Vaello P. Activation of Astrocytes and Microglial Cells and CCL2/CCR2 Upregulation in the Dorsolateral and Ventrolateral Nuclei of Periaqueductal Gray and Rostral Ventromedial Medulla Following Different Types of Sciatic Nerve Injury. Front Cell Neurosci 2018; 12:40. [PMID: 29515373 PMCID: PMC5825898 DOI: 10.3389/fncel.2018.00040] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 02/01/2018] [Indexed: 12/18/2022] Open
Abstract
Peripheral nerve injuries (PNIs) may result in cellular and molecular changes in supraspinal structures possibly involved in neuropathic pain (NPP) maintenance. Activated glial cells in specific supraspinal subregions may affect the facilitatory role of descending pathways. Sterile chronic compression injury (sCCI) and complete sciatic nerve transection (CSNT) in rats were used as NPP models to study the activation of glial cells in the subregions of periaqueductal gray (PAG) and rostral ventromedial medulla (RVM). Molecular markers for activated astrocytes (glial fibrillary acidic protein, GFAP) and microglial cells (OX42) were assessed by quantitative immunohistochemistry and western blotting. The cellular distribution of CCL2/CCR2 was monitored using immunofluorescence. sCCI induced both mechanical and thermal hypersensitivity from day 1 up to 3 weeks post-injury. Unilateral sCCI or CSNT for 3 weeks induced significant activation of astrocytes bilaterally in both dorsolateral (dlPAG) and ventrolateral PAG (vlPAG) compared to naïve or sham-operated rats. More extensive astrocyte activation by CSNT compared to sCCI was induced bilaterally in dlPAG and ipsilaterally in vlPAG. Significantly more extensive activation of astrocytes was also found in RVM after CSNT than sCCI. The CD11b immunopositive region, indicating activated microglial cells, was remarkably larger in dlPAG and vlPAG of both sides from sCCI- and CSNT-operated rats compared to naïve or sham-operated controls. No significant differences in microglial activation were detected in dlPAG or vlPAG after CSNT compared to sCCI. Both nerve injury models induced no significant differences in microglial activation in the RVM. Neurons and activated GFAP+ astrocytes displayed CCL2-immunoreaction, while activated OX42+ microglial cells were CCR2-immunopositive in both PAG and RVM after sCCI and CSNT. Overall, while CSNT induced robust astrogliosis in both PAG and RVM, microglial cell activation was similar in the supraspinal structures in both injury nerve models. Activated astrocytes in PAG and RVM may sustain facilitation of the descending system maintaining NPP, while microglial activation may be associated with a reaction to long-lasting peripheral injury. Microglial activation via CCR2 may be due to neuronal and astrocytal release of CCL2 in PAG and RVM following injury.
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Affiliation(s)
- Petr Dubový
- Department of Anatomy, Division of Neuroanatomy, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ilona Klusáková
- Department of Anatomy, Division of Neuroanatomy, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ivana Hradilová-Svíženská
- Department of Anatomy, Division of Neuroanatomy, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Marek Joukal
- Department of Anatomy, Division of Neuroanatomy, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Pere Boadas-Vaello
- Department of Anatomy, Division of Neuroanatomy, Faculty of Medicine, Masaryk University, Brno, Czechia
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Universitat de Girona, Girona, Spain
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23
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Abstract
Entrapment neuropathies are the most prevalent type of peripheral neuropathy and often a challenge to diagnose and treat. To a large extent, our current knowledge is based on empirical concepts and early (often biomechanical) studies. This Viewpoint will challenge some of the current beliefs with recent advances in both basic and clinical neurosciences. J Orthop Sports Phys Ther 2018;48(2):58-62. doi:10.2519/jospt.2018.0603.
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Henderson LA, Keay KA. Imaging Acute and Chronic Pain in the Human Brainstem and Spinal Cord. Neuroscientist 2017; 24:84-96. [PMID: 28447501 DOI: 10.1177/1073858417703911] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
While acute pain serves as a protective mechanism designed to warn an individual of potential or actual damaging stimuli, chronic pain provides no benefit and is now considered a disease in its own right. Since the advent of human brain imaging techniques, many investigations that have explored the central representation of acute and chronic pain have focused on changes in higher order brain regions. In contrast, far fewer have explored brainstem and spinal cord function, mainly due to significant technical difficulties. In this review, we present some of the recent human brain imaging studies that have specifically explored brainstem and spinal cord function during acute noxious stimuli and in individuals with chronic pain. We focus particularly on investigations that explore changes in areas that receive nociceptor afferents and compare humans and experimental animal data in an attempt to describe both microscopic and macroscopic changes associated with acute and chronic pain.
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Affiliation(s)
- Luke A Henderson
- 1 Department of Anatomy and Histology, University of Sydney, Sydney, New South Wales, Australia
| | - Kevin A Keay
- 1 Department of Anatomy and Histology, University of Sydney, Sydney, New South Wales, Australia
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25
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Boadas-Vaello P, Homs J, Reina F, Carrera A, Verdú E. Neuroplasticity of Supraspinal Structures Associated with Pathological Pain. Anat Rec (Hoboken) 2017; 300:1481-1501. [PMID: 28263454 DOI: 10.1002/ar.23587] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 09/27/2016] [Accepted: 10/18/2016] [Indexed: 12/19/2022]
Abstract
Peripheral nerve and spinal cord injuries, along with other painful syndromes such as fibromyalgia, diabetic neuropathy, chemotherapeutic neuropathy, trigeminal neuralgia, complex regional pain syndrome, and/or irritable bowel syndrome, cause several neuroplasticity changes in the nervous system along its entire axis affecting the different neuronal nuclei. This paper reviews these changes, focusing on the supraspinal structures that are involved in the modulation and processing of pain, including the periaqueductal gray matter, red nucleus, locus coeruleus, rostral ventromedial medulla, thalamus, hypothalamus, basal ganglia, cerebellum, habenula, primary, and secondary somatosensory cortex, motor cortex, mammillary bodies, hippocampus, septum, amygdala, cingulated, and prefrontal cortex. Hyperexcitability caused by the modification of postsynaptic receptor expression, central sensitization, and potentiation of presynaptic delivery of neurotransmitters, as well as the reduction of inhibitory inputs, changes in dendritic spine, neural circuit remodeling, alteration of gray matter, and upregulation of proinflammatory mediators (e.g., cytokines) by reactivation of astrocytes and microglial cells are the main functional, structural, and molecular neuroplasticity changes observed in the above supraspinal structures, associated with pathological pain. Studying these changes in greater depth may lead to the implementation and improvement of new therapeutic strategies against pathological pain. Anat Rec, 300:1481-1501, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Pere Boadas-Vaello
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Judit Homs
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain.,Department of Physical Therapy EUSES-Universitat of Girona, Salt (Girona), Catalonia, 17190, Spain
| | - Francisco Reina
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Ana Carrera
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
| | - Enrique Verdú
- Research Group of Clinical Anatomy, Embryology and Neuroscience (NEOMA), Department of Medical Sciences, Faculty of Medicine, Universitat de Girona, Girona, Catalonia, 17003, Spain
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26
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Fiore NT, Austin PJ. Are the emergence of affective disturbances in neuropathic pain states contingent on supraspinal neuroinflammation? Brain Behav Immun 2016; 56:397-411. [PMID: 27118632 DOI: 10.1016/j.bbi.2016.04.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/11/2016] [Accepted: 04/22/2016] [Indexed: 12/28/2022] Open
Abstract
Neuro-immune interactions contribute to the pathogenesis of neuropathic pain due to peripheral nerve injury. A large body of preclinical evidence supports the idea that the immune system acts to modulate the sensory symptoms of neuropathy at both peripheral and central nervous system sites. The potential involvement of neuro-immune interactions in the highly debilitating affective disturbances of neuropathic pain, such as depression, anhedonia, impaired cognition and reduced motivation has received little attention. This is surprising given the widely accepted view that sickness behaviour, depression, cognitive impairment and other neuropsychiatric conditions can arise from inflammatory mechanisms. Moreover, there is a set of well-described immune-to-brain transmission mechanisms that explain how peripheral inflammation can lead to supraspinal neuroinflammation. In the last 5years increasing evidence has emerged that peripheral nerve injury induces supraspinal changes in cytokine or chemokine expression and alters glial cell activity. In this systematic review, based on strong preclinical evidence, we advance the argument that the emergence of affective disturbances in neuropathic pain states are contingent on pro-inflammatory mediators in the interconnected hippocampal-medial prefrontal circuitry that subserve affective behaviours. We explore how dysregulation of inflammatory mediators in these networks may result in affective disturbances through a wide variety of neuromodulatory mechanisms. There are also promising results from clinical trials showing that anti-inflammatory agents have efficacy in the treatment of a variety of neuropsychiatric conditions including depression and appear suited to sub-groups of patients with elevated pro-inflammatory profiles. Thus, although further research is required, aggressively targeting supraspinal pro-inflammatory mediators at critical time-points in appropriate clinical populations is likely to be a novel avenue to treat debilitating affective disturbances in neuropathic conditions.
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Affiliation(s)
- Nathan T Fiore
- Discipline of Anatomy & Histology, School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Paul J Austin
- Discipline of Anatomy & Histology, School of Medical Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
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Mor D, Kang JWM, Wyllie P, Thirunavukarasu V, Houlton H, Austin PJ, Keay KA. Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities. Mol Pain 2015; 11:50. [PMID: 26283658 PMCID: PMC4538917 DOI: 10.1186/s12990-015-0049-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 07/28/2015] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep-wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a 'TH-naïve' population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain. RESULTS Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG. CONCLUSIONS Our data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.
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Affiliation(s)
- David Mor
- School of Medical Sciences, Discipline of Biomedical Sciences, The University of Sydney, C42, Cumberland Campus, Lidcombe, NSW, 2141, Australia.
| | - James W M Kang
- School of Medical Sciences, Discipline of Biomedical Sciences, The University of Sydney, C42, Cumberland Campus, Lidcombe, NSW, 2141, Australia.
| | - Peter Wyllie
- School of Medical Sciences, Discipline of Anatomy and Histology, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Vignaraja Thirunavukarasu
- School of Medical Sciences, Discipline of Anatomy and Histology, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Hayden Houlton
- School of Medical Sciences, Discipline of Anatomy and Histology, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Paul J Austin
- School of Medical Sciences, Discipline of Anatomy and Histology, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Kevin A Keay
- School of Medical Sciences, Discipline of Anatomy and Histology, The University of Sydney, Sydney, NSW, 2006, Australia.
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Evidence for a distinct neuro-immune signature in rats that develop behavioural disability after nerve injury. J Neuroinflammation 2015; 12:96. [PMID: 25986444 PMCID: PMC4506439 DOI: 10.1186/s12974-015-0318-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/05/2015] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Chronic neuropathic pain is a neuro-immune disorder, characterised by allodynia, hyperalgesia and spontaneous pain, as well as debilitating affective-motivational disturbances (e.g., reduced social interactions, sleep-wake cycle disruption, anhedonia, and depression). The role of the immune system in altered sensation following nerve injury is well documented. However, its role in the development of affective-motivational disturbances remains largely unknown. Here, we aimed to characterise changes in the immune response at peripheral and spinal sites in a rat model of neuropathic pain and disability. METHODS Sixty-two rats underwent sciatic nerve chronic constriction injury (CCI) and were characterised as either Pain and disability, Pain and transient disability or Pain alone on the basis of sensory threshold testing and changes in post-CCI dominance behaviour in resident-intruder interactions. Nerve ultrastructure was assessed and the number of T lymphocytes and macrophages were quantified at the site of injury on day six post-CCI. ATF3 expression was quantified in the dorsal root ganglia (DRG). Using a multiplex assay, eight cytokines were quantified in the sciatic nerve, DRG and spinal cord. RESULTS All CCI rats displayed equal levels of mechanical allodynia, structural nerve damage, and reorganisation. All CCI rats had significant infiltration of macrophages and T lymphocytes to both the injury site and the DRG. Pain and disability rats had significantly greater numbers of T lymphocytes. CCI increased IL-6 and MCP-1 in the sciatic nerve. Examination of disability subgroups revealed increases in IL-6 and MCP-1 were restricted to Pain and disability rats. Conversely, CCI led to a decrease in IL-17, which was restricted to Pain and transient disability and Pain alone rats. CCI significantly increased IL-6 and MCP-1 in the DRG, with IL-6 restricted to Pain and disability rats. CCI rats had increased IL-1β, IL-6 and MCP-1 in the spinal cord. Amongst subgroups, only Pain and disability rats had increased IL-1β. CONCLUSIONS This study has defined individual differences in the immune response at peripheral and spinal sites following CCI in rats. These changes correlated with the degree of disability. Our data suggest that individual immune signatures play a significant role in the different behavioural trajectories following nerve injury, and in some cases may lead to persistent affective-motivational disturbances.
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Austin PJ, Bembrick AL, Denyer GS, Keay KA. Injury-Dependent and Disability-Specific Lumbar Spinal Gene Regulation following Sciatic Nerve Injury in the Rat. PLoS One 2015; 10:e0124755. [PMID: 25905723 PMCID: PMC4408097 DOI: 10.1371/journal.pone.0124755] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 03/06/2015] [Indexed: 12/23/2022] Open
Abstract
Allodynia, hyperalgesia and spontaneous pain are cardinal sensory signs of neuropathic pain. Clinically, many neuropathic pain patients experience affective-motivational state changes, including reduced familial and social interactions, decreased motivation, anhedonia and depression which are severely debilitating. In earlier studies we have shown that sciatic nerve chronic constriction injury (CCI) disrupts social interactions, sleep-wake-cycle and endocrine function in one third of rats, a subgroup reliably identified six days after injury. CCI consistently produces allodynia and hyperalgesia, the intensity of which was unrelated either to the altered social interactions, sleep-wake-cycle or endocrine changes. This decoupling of the sensory consequences of nerve injury from the affective-motivational changes is reported in both animal experiments and human clinical data. The sensory changes triggered by CCI are mediated primarily by functional changes in the lumbar dorsal horn, however, whether lumbar spinal changes may drive different affective-motivational states has never been considered. In these studies, we used microarrays to identify the unique transcriptomes of rats with altered social behaviours following sciatic CCI to determine whether specific patterns of lumbar spinal adaptations characterised this subgroup. Rats underwent CCI and on the basis of reductions in dominance behaviour in resident-intruder social interactions were categorised as having Pain & Disability, Pain & Transient Disability or Pain alone. We examined the lumbar spinal transcriptomes two and six days after CCI. Fifty-four ‘disability-specific’ genes were identified. Sixty-five percent were unique to Pain & Disability rats, two-thirds of which were associated with neurotransmission, inflammation and/or cellular stress. In contrast, 40% of genes differentially regulated in rats without disabilities were involved with more general homeostatic processes (cellular structure, transcription or translation). We suggest that these patterns of gene expression lead to either the expression of disability, or to resilience and recovery, by modifying local spinal circuitry at the origin of ascending supraspinal pathways.
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Affiliation(s)
- Paul J. Austin
- School of Medical Sciences (Anatomy & Histology), The University of Sydney, Sydney, NSW, Australia
| | - Alison L. Bembrick
- School of Medical Sciences (Anatomy & Histology), The University of Sydney, Sydney, NSW, Australia
| | - Gareth S. Denyer
- School of Molecular Bioscience, The University of Sydney, Sydney, NSW, Australia
| | - Kevin A. Keay
- School of Medical Sciences (Anatomy & Histology), The University of Sydney, Sydney, NSW, Australia
- * E-mail:
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Kalman E, Keay KA. Different patterns of morphological changes in the hippocampus and dentate gyrus accompany the differential expression of disability following nerve injury. J Anat 2014; 225:591-603. [PMID: 25269883 DOI: 10.1111/joa.12238] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2014] [Indexed: 12/11/2022] Open
Abstract
Physical and psychological trauma which results in mood disorders and the disruption of complex behaviours is associated with reductions in hippocampal volume. Clinical evaluation of neuropathic pain reveals mood and behavioural change in a significant number of patients. A rat model of neuropathic injury results in complex behavioural changes in a subpopulation (~30%) of injured rats; these changes are co-morbid with a range of other 'disabilities'. The specific objective of this study was to determine in rats the morphology of the hippocampus and dentate gyrus in individuals with and without complex behavioural disruptions following a constriction injury of the sciatic nerve, and to determine whether rats that develop disabilities following nerve injury have a reduced hippocampal volume compared with injured rats with no disabilities. The social behaviours of nerve-injured rats were evaluated before and after nerve injury. The morphology of the hippocampus of rats with and without behavioural disruptions was compared in serial histological sections. Single-housing and repeated social-interaction testing had no effect on the morphology of either the hippocampus or the dentate gyrus. Rats with transient or ongoing disability identified by behavioural disruption following sciatic nerve injury, show bilateral reductions in hippocampal volume, and lateralised reduction in the dentate gyrus (left side). Disabled rats display a combination of behavioural and physiological changes, which resemble many of the criteria used clinically to diagnose mood disorders. They also show reductions in the volume of the hippocampus similar to people with clinically diagnosed mood disorders. The sciatic nerve injury model reveals a similarity to the human neuropathic pain presentation presenting an anatomically specific focus for the investigation of the neural mechanisms underpinning the co-morbidity of chronic pain and mood disorder.
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Affiliation(s)
- Eszter Kalman
- School of Medical Sciences (Anatomy & Histology), University of Sydney, Sydney, NSW, Australia
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Yalcin I, Barthas F, Barrot M. Emotional consequences of neuropathic pain: insight from preclinical studies. Neurosci Biobehav Rev 2014; 47:154-64. [PMID: 25148733 DOI: 10.1016/j.neubiorev.2014.08.002] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 07/15/2014] [Accepted: 08/03/2014] [Indexed: 01/12/2023]
Abstract
Mood disorders such as depression and anxiety are frequently observed in patients suffering from chronic pain, including neuropathic pain. While this comorbidity is clinically well established, the underlying mechanism(s) remained unclear. The recent development of animal models now allows addressing the consequences of neuropathic pain. In this review, we report the preclinical evidences from anatomical, neuroimaging, behavioral, pharmacological and biochemical studies that address the anxiodepressive consequences of neuropathic pain. We present an overview of rodent models of these consequences and we discuss the challenges and parameters to consider for generating these models. We then discuss the possible mechanism(s) underlying anxiodepressive consequences by describing morphological and functional changes. Information is provided concerning neuroanatomical changes and plasticity, including LTP and LTD, in the anterior cingulate cortex, the insula, the hippocampus, the amygdala and the mesolimbic system, neuroendocrine parameters concerning the hypothalamo-pituitary-adrenal axis, neuroimmune response including the role of glial cells and cytokines, monoamine systems and changes in locus coeruleus noradrenergic system, and neurotrophic factors such as BDNF.
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Affiliation(s)
- Ipek Yalcin
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, 67084 Strasbourg, France.
| | - Florent Barthas
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, 67084 Strasbourg, France; Université de Strasbourg, 67084 Strasbourg, France
| | - Michel Barrot
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, 67084 Strasbourg, France
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Kilburn-Watt E, Banati RB, Keay KA. Rats with altered behaviour following nerve injury show evidence of centrally altered thyroid regulation. Brain Res Bull 2014; 107:110-8. [PMID: 25069097 DOI: 10.1016/j.brainresbull.2014.07.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 01/20/2023]
Abstract
The co-morbidity of mood disturbance, in a proportion of patients, is now described across a wide range of chronic disease states. Similarly, a 'Low Thyroid Syndrome' is also reported in a proportion of individuals with chronic diseases. Here, we report on central changes in an animal model of inflammatory stress in which altered social behaviour, representing social disability, persists in a sub-group of rats following injury. We showed in an earlier study that rats with social disability following injury have significantly decreased peripheral thyroid hormones, with no increase in Thyroid Stimulating Hormone (TSH). Only rats identified by behavioural change showed changes in hypothalamic gene expression. In whole hypothalamus extracted RNA, relative expression of mRNA for Thyrotrophin-releasing hormone (TRH) was significantly down-regulated in disabled rats (p=0.039) and deiodinase 3 up-regulated (p=0.006) compared to controls. Specifically in the paraventricular nucleus (PVN), numbers of immunoreactive cells for deiodinase 3-like and thyroid hormone receptor beta-like proteins were decreased in the sub-group with disability compared to the control group (p=0.031 and p=0.011 respectively). In rats with behavioural change post-injury, down-regulation of TRH provides an explanation for the failure of the hypothalamo-pituitary-thyroid (HPT) axis to respond to the post-injury decrease in thyroxine. Decreased local expression of deiodinase 3 protein, resulting in a local increase in T3, offers an explanation for down regulation of TRH in the hypophysiotrophic TRH neurons. It is possible that, in a sub-group of animals identified behaviourally, a mechanism resulting in hypothalamic down-regulation of the HPT axis persists following inflammatory injury.
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Affiliation(s)
- E Kilburn-Watt
- School of Medical Sciences, Faculty of Medicine, The University of Sydney, Australia.
| | - R B Banati
- Medical Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Australia; Australian Nuclear Science and Technology Organisation, Australia.
| | - K A Keay
- School of Medical Sciences, Faculty of Medicine, The University of Sydney, Australia.
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Sutton BC, Opp MR. Musculoskeletal sensitization and sleep: chronic muscle pain fragments sleep of mice without altering its duration. Sleep 2014; 37:505-13. [PMID: 24587573 DOI: 10.5665/sleep.3486] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
STUDY OBJECTIVES Musculoskeletal pain in humans is often associated with poor sleep quality. We used a model in which mechanical hypersensitivity was induced by injection of acidified saline into muscle to study the impact of musculoskeletal sensitization on sleep of mice. DESIGN A one month pre-clinical study was designed to determine the impact of musculoskeletal sensitization on sleep of C57BL/6J mice. METHODS We instrumented mice with telemeters to record the electroencephalogram (EEG) and body temperature. We used an established model of musculoskeletal sensitization in which mechanical hypersensitivity was induced using two unilateral injections of acidified saline (pH 4.0). The injections were given into the gastrocnemius muscle and spaced five days apart. EEG and body temperature recordings started prior to injections (baseline) and continued for three weeks after musculoskeletal sensitization was induced by the second injection. Mechanical hypersensitivity was assessed using von Frey filaments at baseline (before any injections) and on days 1, 3, 7, 14, and 21 after the second injection. RESULTS Mice injected with acidified saline developed bilateral mechanical hypersensitivity at the hind paws as measured by von Frey testing and as compared to control mice and baseline data. Sleep during the light period was fragmented in experimental mice injected with acidified saline, and EEG spectra altered. Musculoskeletal sensitization did not alter the duration of time spent in wakefulness, non-rapid eye movement sleep, or rapid eye movement sleep. CONCLUSIONS Musculoskeletal sensitization in this model results in a distinct sleep phenotype in which sleep is fragmented during the light period, but the overall duration of sleep is not changed. This study suggests the consequences of musculoskeletal pain include sleep disruption, an observation that has been made in the clinical literature but has yet to be studied using preclinical models.
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Affiliation(s)
- Blair C Sutton
- Anesthesiology & Pain Medicine University of Washington, Seattle, WA ; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI
| | - Mark R Opp
- Anesthesiology & Pain Medicine University of Washington, Seattle, WA ; Program of Neurobiology and Behavior University of Washington, Seattle, WA
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Xu JJ, Diaz P, Bie B, Astruc-Diaz F, Wu J, Yang H, Brown DL, Naguib M. Spinal gene expression profiling and pathways analysis of a CB2 agonist (MDA7)-targeted prevention of paclitaxel-induced neuropathy. Neuroscience 2013; 260:185-94. [PMID: 24361916 DOI: 10.1016/j.neuroscience.2013.12.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 11/20/2013] [Accepted: 12/11/2013] [Indexed: 01/07/2023]
Abstract
AIMS Patients receiving paclitaxel often develop peripheral neuropathies. We found that a novel selective cannabinoid CB2 receptor agonist (MDA7) prevents paclitaxel-induced mechanical allodynia in rats and mice. Here we investigated gene expression profiling in the lumbar spinal cord after 14-day treatment of MDA7 in paclitaxel animals and analyzed possible signaling pathways underlying the preventive effect of MDA7 on paclitaxel-induced neuropathy. METHODS Peripheral mechanical allodynia was induced in rats or mice receiving intraperitoneal (i.p.) injection of paclitaxel at a dose of 1mg/kg daily for four consecutive days. MDA7 was administered at a dose of 15mg/kg 15min before paclitaxel and then continued daily for another 10days. Whole-genome gene expression profiling in the lumbar spinal cord of MDA7 and paclitaxel-treated rats was investigated using microarray analysis. The Ingenuity pathway analysis was performed to determine the potential relevant canonical pathways responsible for the effect of MDA7 on paclitaxel-induced peripheral neuropathy. RESULTS We observed that the inflammatory molecular networks including tumor necrosis factor (TNF), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), transforming growth factor beta (TGFβ), and mitogen-activated protein kinases (MAPK) signaling are most relevant to the preventive effect of MDA7 on paclitaxel-induced peripheral neuropathy. In addition, genes encoding molecules that are important in central sensitization such as glutamate transporters and N-methyl-d-aspartate receptor 2B (NMDAR2B), and neuro-immune-related genes such as neuronal nitric oxide synthase (nNOS1), chemokine CX3CL1 (a mediator for microglial activation), toll-like receptor 2 (TLR2), and leptin were differentially modulated by MDA7. CONCLUSION The preventive effect of MDA7 on paclitaxel-induced peripheral allodynia in rats may be associated with genes involved in signal pathways in central sensitization, microglial activation, and neuroinflammation in the spinal cord.
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Affiliation(s)
- J J Xu
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
| | - P Diaz
- The Department of Biomedical and Pharmaceutical Sciences, Core Laboratory for Neuromolecular Production, The University of Montana, Missoula, MT 59812, USA.
| | - B Bie
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
| | - F Astruc-Diaz
- The Department of Biomedical and Pharmaceutical Sciences, Core Laboratory for Neuromolecular Production, The University of Montana, Missoula, MT 59812, USA.
| | - J Wu
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
| | - H Yang
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
| | - D L Brown
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
| | - M Naguib
- Anesthesiology Institute, Cleveland Clinic, 9500 Euclid Avenue - E-31, Cleveland, OH 44195, USA.
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Axonal regeneration after sciatic nerve lesion is delayed but complete in GFAP- and vimentin-deficient mice. PLoS One 2013; 8:e79395. [PMID: 24223940 PMCID: PMC3815133 DOI: 10.1371/journal.pone.0079395] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 09/30/2013] [Indexed: 12/12/2022] Open
Abstract
Peripheral axotomy of motoneurons triggers Wallerian degeneration of injured axons distal to the lesion, followed by axon regeneration. Centrally, axotomy induces loss of synapses (synaptic stripping) from the surface of lesioned motoneurons in the spinal cord. At the lesion site, reactive Schwann cells provide trophic support and guidance for outgrowing axons. The mechanisms of synaptic stripping remain elusive, but reactive astrocytes and microglia appear to be important in this process. We studied axonal regeneration and synaptic stripping of motoneurons after a sciatic nerve lesion in mice lacking the intermediate filament (nanofilament) proteins glial fibrillary acidic protein (GFAP) and vimentin, which are upregulated in reactive astrocytes and Schwann cells. Seven days after sciatic nerve transection, ultrastructural analysis of synaptic density on the somata of injured motoneurons revealed more remaining boutons covering injured somata in GFAP(-/-)Vim(-/-) mice. After sciatic nerve crush in GFAP(-/-)Vim(-/-) mice, the fraction of reinnervated motor endplates on muscle fibers of the gastrocnemius muscle was reduced 13 days after the injury, and axonal regeneration and functional recovery were delayed but complete. Thus, the absence of GFAP and vimentin in glial cells does not seem to affect the outcome after peripheral motoneuron injury but may have an important effect on the response dynamics.
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Schmid AB, Nee RJ, Coppieters MW. Reappraising entrapment neuropathies--mechanisms, diagnosis and management. ACTA ACUST UNITED AC 2013; 18:449-57. [PMID: 24008054 DOI: 10.1016/j.math.2013.07.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/10/2013] [Accepted: 07/13/2013] [Indexed: 12/13/2022]
Abstract
The diagnosis of entrapment neuropathies can be difficult because symptoms and signs often do not follow textbook descriptions and vary significantly between patients with the same diagnosis. Signs and symptoms which spread outside of the innervation territory of the affected nerve or nerve root are common. This Masterclass provides insight into relevant mechanisms that may account for this extraterritorial spread in patients with entrapment neuropathies, with an emphasis on neuroinflammation at the level of the dorsal root ganglia and spinal cord, as well as changes in subcortical and cortical regions. Furthermore, we describe how clinical tests and technical investigations may identify these mechanisms if interpreted in the context of gain or loss of function. The management of neuropathies also remains challenging. Common treatment strategies such as joint mobilisation, neurodynamic exercises, education, and medications are discussed in terms of their potential to influence certain mechanisms at the site of nerve injury or in the central nervous system. The mechanism-oriented approach for this Masterclass seems warranted given the limitations in the current evidence for the diagnosis and management of entrapment neuropathies.
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Affiliation(s)
- Annina B Schmid
- The University of Queensland, Division of Physiotherapy, School of Health and Rehabilitation Sciences, Brisbane (St Lucia), Australia; University of Oxford, Nuffield Department of Clinical Neurosciences, Oxford, United Kingdom.
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Mor D, Keay KA. Differential Regulation of Glucocorticoid Receptor Expression in Distinct Columns of Periaqueductal Grey in Rats with Behavioural Disability Following Nerve Injury. Cell Mol Neurobiol 2013; 33:953-63. [DOI: 10.1007/s10571-013-9962-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 07/03/2013] [Indexed: 10/26/2022]
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Mika J, Zychowska M, Popiolek-Barczyk K, Rojewska E, Przewlocka B. Importance of glial activation in neuropathic pain. Eur J Pharmacol 2013; 716:106-19. [PMID: 23500198 DOI: 10.1016/j.ejphar.2013.01.072] [Citation(s) in RCA: 325] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/17/2012] [Accepted: 01/09/2013] [Indexed: 12/13/2022]
Abstract
Glia plays a crucial role in the maintenance of neuronal homeostasis in the central nervous system. The microglial production of immune factors is believed to play an important role in nociceptive transmission. Pain may now be considered a neuro-immune disorder, since it is known that the activation of immune and immune-like glial cells in the dorsal root ganglia and spinal cord results in the release of both pro- and anti-inflammatory cytokines, as well as algesic and analgesic mediators. In this review we presented an important role of cytokines (IL-1alfa, IL-1beta, IL-2, IL-4, IL-6, IL-10, IL-15, IL-18, TNFalpha, IFNgamma, TGF-beta 1, fractalkine and CCL2); complement components (C1q, C3, C5); metaloproteinases (MMP-2,-9) and many other factors, which become activated on spinal cord and DRG level under neuropathic pain. We discussed the role of the immune system in modulating chronic pain. At present, unsatisfactory treatment of neuropathic pain will seek alternative targets for new drugs and it is possible that anti-inflammatory factors like IL-10, IL-4, IL-1alpha, TGF-beta 1 would fulfill this role. Another novel approach for controlling neuropathic pain can be pharmacological attenuation of glial and immune cell activation. It has been found that propentofylline, pentoxifylline, minocycline and fluorocitrate suppress the development of neuropathic pain. The other way of pain control can be the decrease of pro-nociceptive agents like transcription factor synthesis (NF-kappaB, AP-1); kinase synthesis (MEK, p38MAPK, JNK) and protease activation (cathepsin S, MMP9, MMP2). Additionally, since it is known that the opioid-induced glial activation opposes opioid analgesia, some glial inhibitors, which are safe and clinically well tolerated, are proposed as potential useful ko-analgesic agents for opioid treatment of neuropathic pain. This review pointed to some important mechanisms underlying the development of neuropathic pain, which led to identify some possible new approaches to the treatment of neuropathic pain, based on the more comprehensive knowledge of the interaction between the nervous system and glial and immune cells.
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Affiliation(s)
- Joanna Mika
- Department of Pain Pharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland.
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Marcello L, Cavaliere C, Colangelo A, Bianco M, Cirillo G, Alberghina L, Papa M. Remodelling of supraspinal neuroglial network in neuropathic pain is featured by a reactive gliosis of the nociceptive amygdala. Eur J Pain 2012. [DOI: 10.1002/j.1532-2149.2012.00255.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- L. Marcello
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | - C. Cavaliere
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | | | - M.R. Bianco
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
| | - G. Cirillo
- Laboratory of Morphology of Neural Networks; Department of Medicina Pubblica Clinica e Preventiva; Second University of Napoli; Italy
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Chu H, Sun J, Xu H, Niu Z, Xu M. Effect of periaqueductal gray melanocortin 4 receptor in pain facilitation and glial activation in rat model of chronic constriction injury. Neurol Res 2012; 34:871-88. [PMID: 22889616 DOI: 10.1179/1743132812y.0000000085] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES Substantial evidence shows that spinal melanocortin 4 receptor (MC4R) may participate in regulation of central sensitization and chronic pain condition induced by peripheral nerve injury. Periaqueductal gray (PAG) is an important component of descending pain facilitatory system and takes part in spinal nociceptive information. This research will choose PAG to discuss the effect of MC4R in pain facilitation induced by chronic constriction injury (CCI) and further discuss its effect in glial activity and inflammatory factor levels in nerve injury. METHODS Behavior tests (von Frey test and hot-plate test), semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), and immunohistochemistry were used in this research. RESULTS PAG injection of HS014 (a selective inhibitor of MC4R), not only significantly reduced the established mechanical allodynia and thermal hyperalgesia, but also delayed the development of pain facilitation. Semi-quantitative RT-PCR analysis revealed that MC4R and proopiomelanocortin (POMC) expression in PAG was significantly increased after CCI, but agouti-related protein (AgRP) expression decreased. Immunohistochemistry analysis showed that protein levels of astrocytic marker (GFAP), microglial marker (OX-42), tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were significantly increased, but there was little change of the protein levels of IL-10 following CCI. Furthermore, blockade of MC4R decreased immunoreactivity of glia cells and protein levels of pro-inflammatory cytokines, and increased protein levels of anti-inflammatory cytokine IL-10 after CCI. DISCUSSION This research suggests that activation of MC4R in PAG after peripheral nerve injury participates in pain facilitation by regulating the glial activation and inflammatory cytokines secretion.
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Affiliation(s)
- Haichen Chu
- Department of Anesthesiology, Affiliated Hospital of Medical College, Qingdao University, China.
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Imbe H, Kimura A, Donishi T, Kaneoke Y. Chronic restraint stress decreases glial fibrillary acidic protein and glutamate transporter in the periaqueductal gray matter. Neuroscience 2012; 223:209-18. [PMID: 22890077 DOI: 10.1016/j.neuroscience.2012.08.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 08/01/2012] [Accepted: 08/02/2012] [Indexed: 12/22/2022]
Abstract
Stress affects brain activity and promotes long-term changes in multiple neural systems. Exposure to stressors causes substantial effects on the perception and response to pain. In several animal models, chronic stress produces lasting hyperalgesia. Postmortem studies of stress-related psychiatric disorders have demonstrated a decrease in the number of astrocytes and the level of glial fibrillary acidic protein (GFAP), a marker for astrocyte, in the cerebral cortex. Since astrocytes play vital roles in maintaining neuroplasticity via synapse maintenance and secretion of neurotrophins, impairment of astrocytes is thought to be involved in the neuropathology. In the present study we examined GFAP and excitatory amino acid transporter 2 (EAAT2) protein levels in the periaqueductal gray matter (PAG) after subacute and chronic restraint stresses to clarify changes in descending pain modulatory system in the rat with stress-induced hyperalgesia. Chronic restraint stress (6h/day for 3 weeks), but not subacute restraint stress (6h/day for 3 days), caused a marked mechanical hypersensitivity and aggressive behavior. The chronic restraint stress induced a significant decrease of GFAP protein level in the PAG (32.0 ± 8.9% vs. control group, p<0.05). In immunohistochemical analysis the remarkable decrease of GFAP was observed in the ventrolateral PAG. The EAAT2 protein level in the 3 weeks stress group (79.6 ± 6.8%) was significantly lower compared to that in the control group (100.0 ± 6.1%, p<0.05). In contrast there was no significant difference in the GFAP and EAAT2 protein levels between the control and 3 days stress groups These findings suggest a dysfunction of the PAG that plays pivotal roles in the organization of strategies for coping with stressors and in pain modulation after chronic restraint stress.
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Affiliation(s)
- H Imbe
- Department of Physiology, Wakayama Medical University, Kimiidera 811-1, Wakayama City 641-8509, Japan.
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Naguib M, Xu JJ, Diaz P, Brown DL, Cogdell D, Bie B, Hu J, Craig S, Hittelman WN. Prevention of paclitaxel-induced neuropathy through activation of the central cannabinoid type 2 receptor system. Anesth Analg 2012; 114:1104-20. [PMID: 22392969 DOI: 10.1213/ane.0b013e31824b0191] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Peripheral neuropathy is a major dose-limiting toxicity of chemotherapy, especially after multiple courses of paclitaxel. The development of paclitaxel-induced neuropathy is associated with the activation of microglia followed by the activation and proliferation of astrocytes, and the expression and release of proinflammatory cytokines in the spinal dorsal horn. Cannabinoid type 2 (CB(2)) receptors are expressed in the microglia in neurodegenerative disease models. METHODS To explore the potential of CB(2) agonists for preventing paclitaxel-induced neuropathy, we designed and synthesized a novel CB(2)-selective agonist, namely, MDA7. The effect of MDA7 in preventing paclitaxel-induced allodynia was assessed in rats and in CB(2)(+/+) and CB(2)(-/-) mice. We hypothesized that the CB(2) receptor functions in a negative-feedback loop and that early MDA7 administration can blunt the neuroinflammatory response to paclitaxel and prevent mechanical allodynia through interference with specific signaling pathways. RESULTS We found that MDA7 prevents paclitaxel-induced mechanical allodynia in rats and mice in a dose- and time-dependent manner without compromising paclitaxel's antineoplastic effect. MDA7's neuroprotective effect was absent in CB(2)(-/-) mice and was blocked by CB(2) antagonists, suggesting that MDA7's action directly involves CB(2) receptor activation. MDA7 treatment was found to interfere with early events in the paclitaxel-induced neuroinflammatory response as evidenced by relatively reduced toll-like receptor and CB(2) expression in the lumbar spinal cord, reduced levels of extracellular signal-regulated kinase 1/2 activity, reduced numbers of activated microglia and astrocytes, and reduced secretion of proinflammatory mediators in vivo and in in vitro models. CONCLUSIONS Our findings suggest an innovative therapeutic approach to prevent chemotherapy-induced neuropathy and may permit more aggressive use of active chemotherapeutic regimens with reduced long-term sequelae.
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Affiliation(s)
- Mohamed Naguib
- Institute of Anesthesiology, Cleveland Clinic, 9500 Euclid Ave., NE6-306, Cleveland, OH 44195, USA.
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Wu XF, Liu WT, Liu YP, Huang ZJ, Zhang YK, Song XJ. Reopening of ATP-sensitive potassium channels reduces neuropathic pain and regulates astroglial gap junctions in the rat spinal cord. Pain 2011; 152:2605-2615. [PMID: 21907492 DOI: 10.1016/j.pain.2011.08.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/26/2011] [Accepted: 08/02/2011] [Indexed: 01/27/2023]
Abstract
Adenosine triphosphate-sensitive potassium (K(ATP)) channels are suggested to be involved in pathogenesis of neuropathic pain, but remain underinvestigated in primary afferents and in the spinal cord. We examined alterations of K(ATP) channels in rat spinal cord and tested whether and how they could contribute to neuropathic pain. The results showed that protein expression for K(ATP) channel subunits SUR1, SUR2, and Kir6.1, but not Kir6.2, were significantly downregulated and associated with thermal hyperalgesia and mechanical allodynia after sciatic nerve injury. Spinal administration of a K(ATP) channel opener cromakalim (CRO, 5, 10, and 20 μg, respectively) prevented or suppressed, in a dose-dependent manner, the hyperalgesia and allodynia. Nerve injury also significantly increased expression and phosphorylation of connexin 43, an astroglial gap junction protein. Such an increase of phosphorylation of connexin 43 was inhibited by CRO treatment. Furthermore, preadministration of an astroglial gap junction decoupler carbenoxolone (10 μg) completely reversed the inhibitory effects of CRO treatment on the hyperalgesia and allodynia and phosphorylation of NR1 and NR2B receptors and the subsequent activation of Ca(2+)-dependent signals Ca(2+)/calmodulin-dependent kinase II and cyclic adenosine monophosphate (cAMP) response element binding protein. These findings suggest that nerve injury-induced downregulation of the K(ATP) channels in the spinal cord may interrupt the astroglial gap junctional function and contribute to neuropathic pain, thus the K(ATP) channels opener can reduce neuropathic pain probably partly via regulating the astroglial gap junctions. This study may provide a new strategy for treating neuropathic pain using K(ATP) channel openers in the clinic.
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Affiliation(s)
- Xue-Feng Wu
- Department of Neurobiology, Parker University Research Institute, Dallas, TX, USA State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, Jiangsu, China
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Role of different brain areas in peripheral nerve injury-induced neuropathic pain. Brain Res 2011; 1381:187-201. [DOI: 10.1016/j.brainres.2011.01.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 12/16/2010] [Accepted: 01/03/2011] [Indexed: 02/07/2023]
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Evidence for cellular injury in the midbrain of rats following chronic constriction injury of the sciatic nerve. J Chem Neuroanat 2011; 41:158-69. [PMID: 21291996 DOI: 10.1016/j.jchemneu.2011.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 01/23/2011] [Accepted: 01/24/2011] [Indexed: 01/19/2023]
Abstract
Complex behavioural disabilities, as well as pain, characterise neuropathic pain conditions for which clinical treatment is sought. In rats, chronic constriction injury (CCI) of the sciatic nerve evokes, allodynia and hyperalgesia as well as three distinct patterns of disability, characterised by changes in social and sleep-wake behaviours: (i) Pain & Disability; (ii) Pain & Transient Disability and (iii) Pain alone. Importantly, the degree of allodynia and hyperalgesia is identical for each of these groups. Social-interactions and sleep-wake behaviours are regulated by neural networks, which converge on the periaqueductal grey (PAG). Rats with Pain & Disability show astrocyte activation restricted to the lateral and ventrolateral PAG. Reactive astrocytes are a hallmark of cell death (apoptosis and necrosis). Quantitative real-time RT-PCR for the mRNAs encoding Bax, Bcl-2, heat shock protein 60 (HSP60), mitogen activated kinase kinase (MEK2) and iNOS was performed on the dorsal midbrains of individual, disability characterised rats, extending our earlier Gene-Chip data, showing a select up-regulation of Bax and MEK2 mRNA, and a down-regulation of HSP60 mRNA, in Pain & Disability rats. The anatomical location of TUNEL and cleaved-caspase-3 immunoreactive profiles in the midbrain was also identified. Rats with Pain & Disability showed: (i) pro-apoptotic ratios of Bax:Bcl-2 mRNAs; (ii) decreased HSP60 mRNA; (iii) increased iNOS and MEK2 mRNAs; (iv) TUNEL-positive profiles in the lateral and ventrolateral PAG; and (v) caspase-3 immunoreactive neurons in the mesencephalic nucleus of the trigeminal nerve. Cell death in these specific midbrain regions may underlie the disabilities characterising this subgroup of nerve-injured rats.
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Austin P, Beyer K, Bembrick A, Keay K. Peripheral nerve injury differentially regulates dopaminergic pathways in the nucleus accumbens of rats with either ‘pain alone’ or ‘pain and disability’. Neuroscience 2010; 171:329-43. [DOI: 10.1016/j.neuroscience.2010.08.040] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 08/18/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
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