1
|
Okolo CA, Maran JJ, Watts A, Maripillan J, Harkiolaki M, Martínez AD, Green CR, Mugisho OO. Correlative light and X-ray tomography jointly unveil the critical role of connexin43 channels on inflammation-induced cellular ultrastructural alterations. Heliyon 2024; 10:e27888. [PMID: 38560181 PMCID: PMC10979075 DOI: 10.1016/j.heliyon.2024.e27888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 04/04/2024] Open
Abstract
Non-junctional connexin43 (Cx43) plasma membrane hemichannels have been implicated in several inflammatory diseases, particularly playing a role in ATP release that triggers activation of the inflammasome. Therapies targeting the blocking of the hemichannels to prevent the pathological release or uptake of ions and signalling molecules through its pores are of therapeutic interest. To date, there is no close-to-native, high-definition documentation of the impact of Cx43 hemichannel-mediated inflammation on cellular ultrastructure, neither is there a robust account of the ultrastructural changes that occur following treatment with selective Cx43 hemichannel blockers such as Xentry-Gap19 (XG19). A combination of same-sample correlative high-resolution three-dimensional fluorescence microscopy and soft X-ray tomography at cryogenic temperatures, enabled in the identification of novel 3D molecular interactions within the cellular milieu when comparing behaviour in healthy states and during the early onset or late stages under inflammatory conditions. Notably, our findings suggest that XG19 blockage of connexin hemichannels under pro-inflammatory conditions may be crucial in preventing the direct degradation of connexosomes by lysosomes, without affecting connexin protein translation and trafficking. We also delineated fine and gross cellular phenotypes, characteristic of inflammatory insult or road-to-recovery from inflammation, where XG19 could indirectly prevent and reverse inflammatory cytokine-induced mitochondrial swelling and cellular hypertrophy through its action on Cx43 hemichannels. Our findings suggest that XG19 might have prophylactic and therapeutic effects on the inflammatory response, in line with functional studies.
Collapse
Affiliation(s)
- Chidinma Adanna Okolo
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jack Jonathan Maran
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Amy Watts
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jaime Maripillan
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Maria Harkiolaki
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, New Zealand
| | - Odunayo Omolola Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| |
Collapse
|
2
|
Song Y, Xue T, Guo S, Yu Z, Yun C, Zhao J, Song Z, Liu Z. Inhibition of aquaporin-4 and its subcellular localization attenuates below-level central neuropathic pain by regulating astrocyte activation in a rat spinal cord injury model. Neurotherapeutics 2024; 21:e00306. [PMID: 38237380 DOI: 10.1016/j.neurot.2023.e00306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 11/19/2023] [Indexed: 03/24/2024] Open
Abstract
The mechanisms of central neuropathic pain (CNP) caused by spinal cord injury have not been sufficiently studied. We have found that the upregulation of astrocytic aquaporin-4 (AQP4) aggravated peripheral neuropathic pain after spinal nerve ligation in rats. Using a T13 spinal cord hemisection model, we showed that spinal AQP4 was markedly upregulated after SCI and mainly expressed in astrocytes in the spinal dorsal horn (SDH). Inhibition of AQP4 with TGN020 suppressed astrocyte activation, attenuated the development and maintenance of below-level CNP and promoted motor function recovery in vivo. In primary astrocyte cultures, TGN020 also changed cell morphology, diminished cell proliferation and suppressed astrocyte activation. Moreover, T13 spinal cord hemisection induced cell-surface abundance of the AQP4 channel and perivascular localization in the SDH. Targeted inhibition of AQP4 subcellular localization with trifluoperazine effectively diminished astrocyte activation in vitro and further ablated astrocyte activation, attenuated the development and maintenance of below-level CNP, and accelerated functional recovery in vivo. Together, these results provide mechanistic insights into the roles of AQP4 in the development and maintenance of below-level CNP. Intervening with AQP4, including targeting AQP4 subcellular localization, might emerge as a promising agent to prevent chronic CNP after SCI.
Collapse
Affiliation(s)
- Yu Song
- Department of Spinal Surgery, The Third Affiliated Hospital of Soochow University, Changzhou 213003, China
| | - Tao Xue
- Department of Orthopedics, Wujin Hospital Affiliated with Jiangsu University, Changzhou 213003, China
| | - Shiwu Guo
- Department of Orthopedics, Suzhou Kowloon Hospital, Shanghai Jiao Tong University School of Medicine, Suzhou, 215028, China
| | - Zhen Yu
- Department of Spinal Surgery, The Third Affiliated Hospital of Soochow University, Changzhou 213003, China
| | - Chengming Yun
- Department of Orthopedics, Wujin Hospital Affiliated with Jiangsu University, Changzhou 213003, China
| | - Jie Zhao
- Department of Orthopedics, Wujin Hospital Affiliated with Jiangsu University, Changzhou 213003, China
| | - Zhiwen Song
- Department of Spinal Surgery, The Third Affiliated Hospital of Soochow University, Changzhou 213003, China
| | - Zhiyuan Liu
- Department of Orthopedics, Wujin Hospital Affiliated with Jiangsu University, Changzhou 213003, China; Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, China; The Wujin Clinical College of Xuzhou Medical University, Changzhou 213003, China.
| |
Collapse
|
3
|
Toro CA, Johnson K, Hansen J, Siddiq MM, Vásquez W, Zhao W, Graham ZA, Sáez JC, Iyengar R, Cardozo CP. Boldine modulates glial transcription and functional recovery in a murine model of contusion spinal cord injury. Front Cell Neurosci 2023; 17:1163436. [PMID: 37416508 PMCID: PMC10321410 DOI: 10.3389/fncel.2023.1163436] [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: 06/01/2023] [Indexed: 07/08/2023] Open
Abstract
Membrane channels such as those formed by connexins (Cx) and P2X7 receptors (P2X7R) are permeable to calcium ions and other small molecules such as adenosine triphosphate (ATP) and glutamate. Release of ATP and glutamate through these channels is a key mechanism driving tissue response to traumas such as spinal cord injury (SCI). Boldine, an alkaloid isolated from the Chilean boldo tree, blocks both Cx and Panx1 hemichannels (HCs). To test if boldine could improve function after SCI, boldine or vehicle was administered to treat mice with a moderate severity contusion-induced SCI. Boldine led to greater spared white matter and increased locomotor function as determined by the Basso Mouse Scale and horizontal ladder rung walk tests. Boldine treatment reduced immunostaining for markers of activated microglia (Iba1) and astrocytic (GFAP) markers while increasing that for axon growth and neuroplasticity (GAP-43). Cell culture studies demonstrated that boldine blocked glial HC, specifically Cx26 and Cx30, in cultured astrocytes and blocked calcium entry through activated P2X7R. RT-qPCR studies showed that boldine treatment reduced expression of the chemokine Ccl2, cytokine IL-6 and microglial gene CD68, while increasing expression of the neurotransmission genes Snap25 and Grin2b, and Gap-43. Bulk RNA sequencing revealed that boldine modulated a large number of genes involved in neurotransmission in spinal cord tissue just caudal from the lesion epicenter at 14 days after SCI. Numbers of genes regulated by boldine was much lower at 28 days after injury. These results indicate that boldine treatment ameliorates injury and spares tissue to increase locomotor function.
Collapse
Affiliation(s)
- Carlos A. Toro
- Spinal Cord Damage Research Center, James J. Peters VA Medical Center, Bronx, NY, United States
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Kaitlin Johnson
- Spinal Cord Damage Research Center, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Jens Hansen
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Mustafa M. Siddiq
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Walter Vásquez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile
- Instituto de Neurociencias, Centro Interdisciplinario De Neurociencia De Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Wei Zhao
- Spinal Cord Damage Research Center, James J. Peters VA Medical Center, Bronx, NY, United States
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Zachary A. Graham
- Florida Institute for Human and Machine Cognition, Pensacola, FL, United States
- Department of Cell, Developmental, and Integrative Biology, University of Alabama, Birmingham, AL, United States
- Research Service, Birmingham Veterans Affairs Health Care System, Birmingham, AL, United States
| | - Juan C. Sáez
- Instituto de Neurociencias, Centro Interdisciplinario De Neurociencia De Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Ravi Iyengar
- Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Christopher P. Cardozo
- Spinal Cord Damage Research Center, James J. Peters VA Medical Center, Bronx, NY, United States
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- Rehabilitative Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| |
Collapse
|
4
|
Yang Q, Jiang M, Xu S, Yang L, Yang P, Song Y, Zhu H, Wang Y, Sun Y, Yan C, Yuan Z, Liu X, Bai Z. Mirror image pain mediated by D2 receptor regulation of astrocytic Cx43 phosphorylation and channel opening. Biochim Biophys Acta Mol Basis Dis 2023; 1869:166657. [PMID: 36716897 DOI: 10.1016/j.bbadis.2023.166657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/21/2022] [Accepted: 01/20/2023] [Indexed: 01/29/2023]
Abstract
Mirror image pain (MIP), a clinical syndrome of contralateral pain hypersensitivity caused by unilateral injury, has been identified in various neuropathological conditions. Gap junctional protein Connexin 43 (Cx43), its phosphorylation levels and dopamine D2 receptor (DRD2) play key integrating roles in pain processing. We presume D2DR activity may affect Cx43 hemichannel opening via Cx43 phosphorylation levels to regulate MIP. This study shows that spinal astrocytic Cx43 directly interacts with DRD2 to mediate MIP. DRD2 and Cx43 expression levels were asymmetrically elevated in bilateral spinal during MIP, and DRD2 modulated the opening of primary astrocytic Cx43 hemichannels. Furthermore, Cx43 phosphorylation at Ser373 was increased during MIP, but decreased in DRD2 knockout (KO) mice. Finally, activation of spinal protein kinase A (PKA) altered the expression of Cx43 and its phosphorylation bilaterally, thus reversing the analgesic effect in DRD2 KO mice. Together, these data reveal that spinal Cx43 phosphorylation and channel opening are regulated by DRD2 via PKA activation, and that spinal Cx43 and DRD2 are key molecular sensors mediating mirror image pain.
Collapse
Affiliation(s)
- Qinghu Yang
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China; Yanan Engineering & Technological Research Centre for Resource Peptide Drugs, Yanan 716000, China; Yanan Key Laboratory for Neural Immuno-Tumor and Stem Cell, Yanan 716000, China
| | - Ming Jiang
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China; Yanan Engineering & Technological Research Centre for Resource Peptide Drugs, Yanan 716000, China; Yanan Key Laboratory for Neural Immuno-Tumor and Stem Cell, Yanan 716000, China
| | - Sen Xu
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Liang Yang
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China; Yanan Engineering & Technological Research Centre for Resource Peptide Drugs, Yanan 716000, China; Yanan Key Laboratory for Neural Immuno-Tumor and Stem Cell, Yanan 716000, China
| | - Pan Yang
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Yutian Song
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Hongni Zhu
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Yu Wang
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Yahan Sun
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Chengxiang Yan
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Zhaoyue Yuan
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China
| | - Xia Liu
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China; Yanan Engineering & Technological Research Centre for Resource Peptide Drugs, Yanan 716000, China; Yanan Key Laboratory for Neural Immuno-Tumor and Stem Cell, Yanan 716000, China.
| | - Zhantao Bai
- School of Life Science & Research Center for Natural Peptide Drugs, Shaanxi Engineering & Technological Research Centre for Conservation & Utilization of Regional Biological Resources, Yanan University, Yanan 716000, China; Yanan Engineering & Technological Research Centre for Resource Peptide Drugs, Yanan 716000, China; Yanan Key Laboratory for Neural Immuno-Tumor and Stem Cell, Yanan 716000, China.
| |
Collapse
|
5
|
Toro CA, Johnson K, Hansen J, Siddiq MM, Vásquez W, Zhao W, Graham ZA, Sáez JC, Iyengar R, Cardozo CP. Boldine modulates glial transcription and functional recovery in a murine model of contusion spinal cord injury. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528337. [PMID: 36824813 PMCID: PMC9949031 DOI: 10.1101/2023.02.15.528337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Membrane channels such as connexins (Cx), pannexins (Panx) and P2X 7 receptors (P2X 7 R) are permeable to calcium ions and other small molecules such as ATP and glutamate. Release of ATP and glutamate through these channels is a key mechanism driving tissue response to traumas such as spinal cord injury (SCI). Boldine, an alkaloid isolated from the Chilean boldo tree, blocks both Cx hemichannels (HC) and Panx. To test if boldine could improve function after SCI, boldine or vehicle was administered to treat mice with a moderate severity contusion-induced SCI. Boldine led to greater spared white matter and increased locomotor function as determined by the Basso Mouse Scale and horizontal ladder rung walk tests. Boldine treatment reduced immunostaining for markers of activated microglia (Iba1) and astrocytic (GFAP) markers while increasing that for axon growth and neuroplasticity (GAP-43). Cell culture studies demonstrated that boldine blocked glial HC, specifically Cx26 and Cx30, in cultured astrocytes and blocked calcium entry through activated P2X 7 R. RT-qPCR studies showed that boldine treatment reduced expression of the chemokine Ccl2, cytokine IL-6 and microglial gene CD68, while increasing expression of the neurotransmission genes Snap25 and Grin2b, and Gap-43. Bulk RNA sequencing (of the spinal cord revealed that boldine modulated a large number of genes involved in neurotransmission in in spinal cord tissue just below the lesion epicenter at 14 days after SCI. Numbers of genes regulated by boldine was much lower at 28 days after injury. These results indicate that boldine treatment ameliorates injury and spares tissue to increase locomotor function.
Collapse
|
6
|
Chin JS, Milbreta U, Becker DL, Chew SY. Targeting connexin 43 expression via scaffold mediated delivery of antisense oligodeoxynucleotide preserves neurons, enhances axonal extension, reduces astrocyte and microglial activation after spinal cord injury. J Tissue Eng 2023; 14:20417314221145789. [PMID: 36798907 PMCID: PMC9926388 DOI: 10.1177/20417314221145789] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Accepted: 12/01/2022] [Indexed: 02/12/2023] Open
Abstract
Injury to the central nervous system (CNS) provokes an inflammatory reaction and secondary damage that result in further tissue damage and destruction of neurons away from the injury site. Upon injury, expression of connexin 43 (Cx43), a gap junction protein, upregulates and is responsible for the spread and amplification of cell death signals through these gap junctions. In this study, we hypothesise that the downregulation of Cx43 by scaffold-mediated controlled delivery of antisense oligodeoxynucleotide (asODN), would minimise secondary injuries and cell death, and thereby support tissue regeneration after nerve injuries. Specifically, using spinal cord injury (SCI) as a proof-of-principle, we utilised a fibre-hydrogel scaffold for sustained delivery of Cx43asODN, while providing synergistic topographical cues to guide axonal ingrowth. Correspondingly, scaffolds loaded with Cx43asODN, in the presence of NT-3, suppressed Cx43 up-regulation after complete transection SCI in rats. These scaffolds facilitated the sustained release of Cx43asODN for up to 25 days. Importantly, asODN treatment preserved neurons around the injury site, promoted axonal extension, decreased glial scarring, and reduced microglial activation after SCI. Our results suggest that implantation of such scaffold-mediated asODN delivery platform could serve as an effective alternative SCI therapeutic approach.
Collapse
Affiliation(s)
- Jiah Shin Chin
- Nanyang Institute of Health Technologies, Interdisciplinary Graduate School, Nanyang Technological University, Singapore,School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore
| | - Ulla Milbreta
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore
| | - David L Becker
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore,Skin Research Institute Singapore, Clinical Sciences Building, Singapore
| | - Sing Yian Chew
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore,School of Materials Science and Engineering, Nanyang Technological University, Singapore,Sing Yian Chew, School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 62 Nanyang Drive, 639798, Singapore.
| |
Collapse
|
7
|
Nakajima N, Ohnishi Y, Yamamoto M, Setoyama D, Imai H, Takenaka T, Matsumoto M, Hosomi K, Saitoh Y, Furue H, Kishima H. Excess intracellular ATP causes neuropathic pain following spinal cord injury. Cell Mol Life Sci 2022; 79:483. [PMID: 35972649 PMCID: PMC11072579 DOI: 10.1007/s00018-022-04510-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/16/2022] [Accepted: 08/01/2022] [Indexed: 11/03/2022]
Abstract
Intractable neuropathic pain following spinal cord injury (NP-SCI) reduces a patient's quality of life. Excessive release of ATP into the extracellular space evokes neuroinflammation via purinergic receptor. Neuroinflammation plays an important role in the initiation and maintenance of NP. However, little is known about whether or not extracellular ATP cause NP-SCI. We found in the present study that excess of intracellular ATP at the lesion site evokes at-level NP-SCI. No significant differences in the body weight, locomotor function, or motor behaviors were found in groups that were negative and positive for at-level allodynia. The intracellular ATP level at the lesion site was significantly higher in the allodynia-positive mice than in the allodynia-negative mice. A metabolome analysis revealed that there were no significant differences in the ATP production or degradation between allodynia-negative and allodynia-positive mice. Dorsal horn neurons in allodynia mice were found to be inactivated in the resting state, suggesting that decreased ATP consumption due to neural inactivity leads to a build-up of intracellular ATP. In contrast to the findings in the resting state, mechanical stimulation increased the neural activity of dorsal horn and extracellular ATP release at lesion site. The forced production of intracellular ATP at the lesion site in non-allodynia mice induced allodynia. The inhibition of P2X4 receptors in allodynia mice reduced allodynia. These results suggest that an excess buildup of intracellular ATP in the resting state causes at-level NP-SCI as a result of the extracellular release of ATP with mechanical stimulation.
Collapse
Affiliation(s)
- Nobuhiko Nakajima
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yuichiro Ohnishi
- Department of Research Promotion and Management, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka, 564-8565, Japan.
- Department of Neurosurgery, Osaka Gyoumeikan Hospital, Osaka, Japan.
| | - Masamichi Yamamoto
- Department of Research Promotion and Management, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka, 564-8565, Japan.
| | - Daiki Setoyama
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hirohiko Imai
- Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan
| | - Tomofumi Takenaka
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Mari Matsumoto
- Department of Research Promotion and Management, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka, 564-8565, Japan
| | - Koichi Hosomi
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
- Department of Neuromodulation and Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Yoichi Saitoh
- Department of Neuromodulation and Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Hidemasa Furue
- Department of Neurophysiology, Hyogo College of Medicine, Hyogo, Japan
| | - Haruhiko Kishima
- Department of Neurosurgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| |
Collapse
|
8
|
Zhang C, Yan Z, Maknojia A, Riquelme MA, Gu S, Booher G, Wallace DJ, Bartanusz V, Goswami A, Xiong W, Zhang N, Mader MJ, An Z, Sayre NL, Jiang JX. Inhibition of astrocyte hemichannel improves recovery from spinal cord injury. JCI Insight 2021; 6:134611. [PMID: 33682795 PMCID: PMC8021110 DOI: 10.1172/jci.insight.134611] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/27/2021] [Indexed: 11/25/2022] Open
Abstract
Spinal cord injury (SCI) causes severe disability, and the current inability to restore function to the damaged spinal cord leads to lasting detrimental consequences to patients. One strategy to reduce SCI morbidity involves limiting the spread of secondary damage after injury. Previous studies have shown that connexin 43 (Cx43), a gap junction protein richly expressed in spinal cord astrocytes, is a potential mediator of secondary damage. Here, we developed a specific inhibitory antibody, mouse-human chimeric MHC1 antibody (MHC1), that inhibited Cx43 hemichannels, but not gap junctions, and reduced secondary damage in 2 incomplete SCI mouse models. MHC1 inhibited the activation of Cx43 hemichannels in both primary spinal astrocytes and astrocytes in situ. In both SCI mouse models, administration of MHC1 after SCI significantly improved hind limb locomotion function. Remarkably, a single administration of MHC1 30 minutes after injury improved the recovery up to 8 weeks post-SCI. Moreover, MHC1 treatment decreased gliosis and lesion sizes, increased white and gray matter sparing, and improved neuronal survival. Together, these results suggest that inhibition of Cx43 hemichannel function after traumatic SCI reduces secondary damage, limits perilesional gliosis, and improves functional recovery. By targeting hemichannels specifically with an antibody, this study provides a potentially new, innovative therapeutic approach in treating SCI.
Collapse
Affiliation(s)
- Chao Zhang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- The Second Xiangya Hospital of Central South University, Changsha, China
| | - Zhao Yan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- The Second Xiangya Hospital of Central South University, Changsha, China
| | - Asif Maknojia
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Manuel A Riquelme
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Grant Booher
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - David J Wallace
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Viktor Bartanusz
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Akshay Goswami
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Wei Xiong
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Ningyan Zhang
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Michael J Mader
- Audie L. Murphy VA Hospital, South Texas Veteran's Health Care System, San Antonio, Texas, USA
| | - Zhiqiang An
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Naomi L Sayre
- Department of Neurosurgery, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- Audie L. Murphy VA Hospital, South Texas Veteran's Health Care System, San Antonio, Texas, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| |
Collapse
|
9
|
Kwiecien JM, Dąbrowski W, Yaron JR, Zhang L, Delaney KH, Lucas AR. The Role of Astrogliosis in Formation of the Syrinx in Spinal Cord Injury. Curr Neuropharmacol 2021; 19:294-303. [PMID: 32691715 PMCID: PMC8033977 DOI: 10.2174/1570159x18666200720225222] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/09/2020] [Accepted: 07/16/2020] [Indexed: 12/28/2022] Open
Abstract
A massive localized trauma to the spinal cord results in complex pathologic events driven by necrosis and vascular damage which in turn leads to hemorrhage and edema. Severe, destructive and very protracted inflammatory response is characterized by infiltration by phagocytic macrophages of a site of injury which is converted into a cavity of injury (COI) surrounded by astroglial reaction mounted by the spinal cord. The tissue response to the spinal cord injury (SCI) has been poorly understood but the final outcome appears to be a mature syrinx filled with the cerebrospinal fluid with related neural tissue loss and permanent neurologic deficits. This paper reviews known pathologic mechanisms involved in the formation of the COI after SCI and discusses the integrative role of reactive astrogliosis in mechanisms involved in the removal of edema after the injury. A large proportion of edema fluid originating from the trauma and then from vasogenic edema related to persistent severe inflammation, may be moved into the COI in an active process involving astrogliosis and specifically over-expressed aquaporins.
Collapse
Affiliation(s)
- Jacek M. Kwiecien
- Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada
| | - Wojciech Dąbrowski
- Department of Anaesthesiology and Intensive Therapy, Medical University of Lublin, ul. Jaczewskiego 8, Lublin 20-090 Poland
| | - Jordan R Yaron
- Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ, U.S.A
| | - Liqiang Zhang
- Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ, U.S.A
| | - Kathleen H. Delaney
- Department of Pathology and Molecular Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada
| | - Alexandra R. Lucas
- Center for Personalized Diagnostics and Center for Immunotherapy, Vaccines and Virotherapy, Biodesign Institute, Arizona State University, Tempe, AZ, U.S.A
| |
Collapse
|
10
|
Abou-Mrad Z, Alomari SO, Bsat S, Moussalem CK, Alok K, El Houshiemy MN, Alomari AO, Minassian GB, Omeis IA. Role of connexins in spinal cord injury: An update. Clin Neurol Neurosurg 2020; 197:106102. [DOI: 10.1016/j.clineuro.2020.106102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/16/2020] [Accepted: 07/18/2020] [Indexed: 01/25/2023]
|
11
|
Papaneophytou C, Georgiou E, Kleopa KA. The role of oligodendrocyte gap junctions in neuroinflammation. Channels (Austin) 2020; 13:247-263. [PMID: 31232168 PMCID: PMC6602578 DOI: 10.1080/19336950.2019.1631107] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Gap junctions (GJs) provide channels for direct cell-to-cell connectivity serving the homeostasis in several organs of vertebrates including the central (CNS) and peripheral (PNS) nervous systems. GJs are composed of connexins (Cx), which show a highly distinct cellular and subcellular expression pattern. Oligodendrocytes, the myelinating cells of the CNS, are characterized by extensive GJ connectivity with each other as well as with astrocytes. The main oligodendrocyte connexins forming these GJ channels are Cx47 and Cx32. The importance of these channels has been highlighted by the discovery of human diseases caused by mutations in oligodendrocyte connexins, manifesting with leukodystrophy or transient encephalopathy. Experimental models have provided further evidence that oligodendrocyte GJs are essential for CNS myelination and homeostasis, while a strong inflammatory component has been recognized in the absence of oligodendrocyte connexins. Further studies revealed that connexins are also disrupted in multiple sclerosis (MS) brain, and in experimental models of induced inflammatory demyelination. Moreover, induced demyelination was more severe and associated with higher degree of CNS inflammation in models with oligodendrocyte GJ deficiency, suggesting that disrupted connexin expression in oligodendrocytes is not only a consequence but can also drive a pro-inflammatory environment in acquired demyelinating disorders such as MS. In this review, we summarize the current insights from human disorders as well as from genetic and acquired models of demyelination related to oligodendrocyte connexins, with the remaining challenges and perspectives.
Collapse
Affiliation(s)
- Christos Papaneophytou
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus.,b Department of Life and Health Sciences, School of Sciences and Engineering , University of Nicosia , Nicosia , Cyprus
| | - Elena Georgiou
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus
| | - Kleopas A Kleopa
- a Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine , Nicosia , Cyprus.,c Neurology Clinics , the Cyprus Institute of Neurology and Genetics, and the Cyprus School of Molecular Medicine , Nicosia , Cyprus
| |
Collapse
|
12
|
Vicario N, Turnaturi R, Spitale FM, Torrisi F, Zappalà A, Gulino R, Pasquinucci L, Chiechio S, Parenti C, Parenti R. Intercellular communication and ion channels in neuropathic pain chronicization. Inflamm Res 2020; 69:841-850. [PMID: 32533221 DOI: 10.1007/s00011-020-01363-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/13/2020] [Accepted: 05/17/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Neuropathic pain is caused by primary lesion or dysfunction of either peripheral or central nervous system. Due to its complex pathogenesis, often related to a number of comorbidities, such as cancer, neurodegenerative and neurovascular diseases, neuropathic pain still represents an unmet clinical need, lacking long-term effective treatment and complex case-by-case approach. AIM AND METHODS We analyzed the recent literature on the role of selective voltage-sensitive sodium, calcium and potassium permeable channels and non-selective gap junctions (GJs) and hemichannels (HCs) in establishing and maintaining chronic neuropathic conditions. We finally focussed our review on the role of extracellular microenvironment modifications induced by resident glial cells and on the recent advances in cell-to-cell and cell-to-extracellular environment communication in chronic neuropathies. CONCLUSION In this review, we provide an update on the current knowledge of neuropathy chronicization processes with a focus on both neuronal and glial ion channels, as well as on channel-mediated intercellular communication.
Collapse
Affiliation(s)
- Nunzio Vicario
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rita Turnaturi
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Federica Maria Spitale
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Filippo Torrisi
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Agata Zappalà
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Rosario Gulino
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy
| | - Lorella Pasquinucci
- Section of Medicinal Chemistry, Department of Drug Sciences, University of Catania, Catania, Italy
| | - Santina Chiechio
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy
- Oasi Research Institute IRCCS, Troina, Italy
| | - Carmela Parenti
- Section of Pharmacology, Department of Drug Sciences, University of Catania, Catania, Italy.
| | - Rosalba Parenti
- Section of Physiology, Department of Biomedical and Biotechnological Sciences, University of Catania, Catania, Italy.
| |
Collapse
|
13
|
Debarba LK, Marangon PB, Borges BC, Veida-Silva H, Venâncio JC, Almeida-Pereira G, Antunes-Rodrigues J, Elias LLK. Neonatal nutritional programming induces gliosis and alters the expression of T-cell protein tyrosine phosphatase and connexins in male rats. Horm Behav 2020; 120:104690. [PMID: 31954709 DOI: 10.1016/j.yhbeh.2020.104690] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 12/20/2019] [Accepted: 01/12/2020] [Indexed: 01/17/2023]
Abstract
Changes to neonatal nutrition result in long-lasting impairments in energy balance, which may be described as metabolic programing. Astrocytes, which are interconnected by gap junctions, have emerged as important players in the hypothalamic control of food intake. In order to study the effects of nutritional programming on glial morphology and protein expression, cross-fostered male Wistar rats at postnatal day 3 were assigned to three groups based on litter size: small litter (3 pups per dam, SL), normal litter (10 pups per dam, NL), and large litter (16 pups per dam, LL). Rats from the SL group exhibited higher body weight throughout the study and hyperphagia after weaning. LL animals exhibited hyperphagia, high energy efficiency and catch-up of body weight after weaning. Both the SL and LL groups at postnatal day 60 (PN60) exhibited increased levels of plasma leptin, the Lee index (as an index of obesity), adiposity content, immunoreactivity toward T-cell protein tyrosine phosphatase (TCPTP), and glial fibrillary acidic protein (GFAP) in the arcuate nucleus (ARC) of the hypothalamus. Astrocyte morphology was altered in the ARC of SL and LL animals, and this effect occurred in parallel with a reduction in immunoreactivity toward connexin 30 (CX30). The data obtained demonstrate that both neonatal over- and underfeeding promote not only alterations in the metabolic status but also morphological changes in glial cells in parallel with increasing TCPTP and changes in connexin expression.
Collapse
Affiliation(s)
- Lucas Kniess Debarba
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900.
| | - Paula Beatriz Marangon
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - Beatriz C Borges
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - Hellen Veida-Silva
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - Jade Cabestre Venâncio
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - Gislaine Almeida-Pereira
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - José Antunes-Rodrigues
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| | - Lucila Leico Kagohara Elias
- Department of Physiology, Ribeirao Preto Medical School, University of Sao Paulo, Sao Paulo, Brazil. 14049-900
| |
Collapse
|
14
|
Mat Nor MN, Rupenthal ID, Green CR, Acosta ML. Connexin Hemichannel Block Using Orally Delivered Tonabersat Improves Outcomes in Animal Models of Retinal Disease. Neurotherapeutics 2020; 17:371-387. [PMID: 31637594 PMCID: PMC7007471 DOI: 10.1007/s13311-019-00786-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Increased Connexin43 hemichannel opening is associated with inflammasome pathway activation and inflammation in a range of pathologies including ocular disorders, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). In this study, the effect on retinal function and morphology of clinically safe doses of orally delivered tonabersat, a small molecule connexin hemichannel blocker, was investigated in the light-damaged retina animal model of dry AMD and in a spontaneous rat model of DR. Clinical parameters (fundus imaging, optical coherence tomography (OCT), and electroretinography) and inflammatory markers (immunohistochemistry for Iba-1 microglial marker, astrocyte marker glial fibrillary acidic protein, and Connexin43 protein expression) were assessed. Tonabersat treatment reduced inflammation in the retina in parallel with preservation of retinal photoreceptor function when assessed up to 3 months post light damage in the dry AMD model. In the DR model, clinical signs, including the presence of aneurysms confirmed using Evans blue dye perfusion, were reduced after daily tonabersat treatment for 2 weeks. Inflammation was also reduced and retinal electrical function restored. Tonabersat regulates assembly of the inflammasome (NLRP3) through Connexin43 hemichannel block, with the potential to reduce inflammation, restore vascular integrity and improve anatomical along with some functional outcomes in retinal disease.
Collapse
Affiliation(s)
- Mohd Nasir Mat Nor
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Faculty of Medicine, University of Sultan Zainal Abidin, Kuala Terengganu, Malaysia
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
| |
Collapse
|
15
|
Vicario N, Pasquinucci L, Spitale FM, Chiechio S, Turnaturi R, Caraci F, Tibullo D, Avola R, Gulino R, Parenti R, Parenti C. Simultaneous Activation of Mu and Delta Opioid Receptors Reduces Allodynia and Astrocytic Connexin 43 in an Animal Model of Neuropathic Pain. Mol Neurobiol 2019; 56:7338-7354. [PMID: 31030416 DOI: 10.1007/s12035-019-1607-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 04/12/2019] [Indexed: 12/27/2022]
Abstract
Neuropathic pain is a chronic condition triggered by lesions to the somatosensory nervous system in which pain stimuli occur spontaneously or as pathologically amplified responses. In this scenario, the exchange of signaling molecules throughout cell-to-cell and cell-to-extracellular environment communications plays a key role in the transition from acute to chronic pain. As such, connexin 43 (Cx43), the core glial gap junction and hemichannel-forming protein, is considered a triggering factor for disease chronicization in the central nervous system (CNS). Drugs targeting μ opioid receptors (MOR) are currently used for moderate to severe pain conditions, but their use in chronic pain is limited by the tolerability profile. δ opioid receptors (DOR) have become attractive targets for the treatment of persistent pain and have been associated with the inhibition of pain-sustaining factors. Moreover, it has been shown that simultaneous targeting of MOR and DOR leads to an improved pharmacological fingerprint. Herein, we aimed to study the effects of the benzomorphan ligand LP2, a multitarget MOR/DOR agonist, in an experimental model of neuropathic pain induced by the unilateral sciatic nerve chronic constriction injury (CCI) on male Sprague-Dawley rats. Results showed that LP2 significantly ameliorated mechanical allodynia from the early phase of treatment up to 21 days post-ligatures. We additionally showed that LP2 prevented CCI-induced Cx43 alterations and pro-apoptotic signaling in the CNS. These findings increase the knowledge of neuropathic pain development and the role of spinal astrocytic Cx43, suggesting new approaches for the treatment of neuropathic pain.
Collapse
Affiliation(s)
- Nunzio Vicario
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95123, Catania, Italy
| | - Lorella Pasquinucci
- Department of Drug Sciences, Section of Medicinal Chemistry, University of Catania, 95125, Catania, Italy
| | - Federica M Spitale
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95123, Catania, Italy
| | - Santina Chiechio
- Department of Drug Sciences, Section of Pharmacology and Toxicology, University of Catania, 95125, Catania, Italy.,Oasi Research Institute-IRCCS, 94018, Troina, Italy
| | - Rita Turnaturi
- Department of Drug Sciences, Section of Medicinal Chemistry, University of Catania, 95125, Catania, Italy
| | - Filippo Caraci
- Department of Drug Sciences, Section of Pharmacology and Toxicology, University of Catania, 95125, Catania, Italy.,Oasi Research Institute-IRCCS, 94018, Troina, Italy
| | - Daniele Tibullo
- Department of Biomedical and Biotechnological Sciences, Section of Biochemistry, University of Catania, 95123, Catania, Italy
| | - Roberto Avola
- Department of Biomedical and Biotechnological Sciences, Section of Biochemistry, University of Catania, 95123, Catania, Italy
| | - Rosario Gulino
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95123, Catania, Italy
| | - Rosalba Parenti
- Department of Biomedical and Biotechnological Sciences, Section of Physiology, University of Catania, 95123, Catania, Italy.
| | - Carmela Parenti
- Department of Drug Sciences, Section of Pharmacology and Toxicology, University of Catania, 95125, Catania, Italy
| |
Collapse
|
16
|
Dispelling myths about connexins, pannexins and P2X7 in hypoxic-ischemic central nervous system. Neurosci Lett 2019; 695:76-85. [PMID: 29195910 DOI: 10.1016/j.neulet.2017.11.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 10/07/2017] [Accepted: 11/21/2017] [Indexed: 01/17/2023]
Abstract
In membrane physiology, as in other fields, myths or speculations may be repeated so often and so widely that they are perceived as facts. To some extent, this has occurred with regard to gap junctions, hemichannels, pannexin channels and P2X7 (ionotropic receptors), especially concerning the interpretation of the individual role of these channels in hypoxic-ischemic CNS since these channels may be closed by the same pharmacological blockers. Significance of existing controversial data are highlighted and contradictory views from different groups are critically discussed herein.
Collapse
|
17
|
Abstract
Due to strong electrical coupling, syncytial isopotentiality emerges as a physiological mechanism that coordinates astrocytes into a highly efficient system in brain homeostasis. Although this electrophysiological phenomenon has now been observed in astrocyte networks established by different astrocyte subtypes, the spinal cord remains a brain region that is still unexplored. In ALDH1L1-eGFP transgenic mice, astrocytes can be visualized by confocal microscopy and the spinal cord astrocytes in grey matter are organized in a distinctive pattern. Namely, each astrocyte resides with more directly coupled neighbors at shorter interastrocytic distances compared to protoplasmic astrocytes in the hippocampal CA1 region. In whole-cell patch clamp recording, the spinal cord grey matter astrocytes exhibit passive K+ conductance and a highly hyperpolarized membrane potential of −80 mV. To answer whether syncytial isopotentiality is a shared feature of astrocyte networks in the spinal cord, the K+ content in a physiological recording solution was substituted by equimolar Na+ for whole-cell recording in spinal cord slices. In uncoupled single astrocytes, this substitution of endogenous K+ with Na+ is known to depolarize astrocytes to around 0 mV as predicted by Goldman–Hodgkin–Katz (GHK) equation. In contrast, the existence of syncytial isopotentiality is indicated by a disobedience of the GHK predication as the recorded astrocyte’s membrane potential remains at a quasi-physiological level that is comparable to its neighbors due to strong electrical coupling. We showed that the strength of syncytial isopotentiality in spinal cord grey matter is significantly stronger than that of astrocyte network in the hippocampal CA1 region. Thus, this study corroborates the notion that syncytial isopotentiality most likely represents a system-wide electrical feature of astrocytic networks throughout the brain.
Collapse
|
18
|
Mugisho OO, Green CR, Zhang J, Binz N, Acosta ML, Rakoczy E, Rupenthal ID. Immunohistochemical Characterization of Connexin43 Expression in a Mouse Model of Diabetic Retinopathy and in Human Donor Retinas. Int J Mol Sci 2017; 18:ijms18122567. [PMID: 29186067 PMCID: PMC5751170 DOI: 10.3390/ijms18122567] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 11/21/2017] [Accepted: 11/24/2017] [Indexed: 12/25/2022] Open
Abstract
Diabetic retinopathy (DR) develops due to hyperglycemia and inflammation-induced vascular disruptions in the retina with connexin43 expression patterns in the disease still debated. Here, the effects of hyperglycemia and inflammation on connexin43 expression in vitro in a mouse model of DR and in human donor tissues were evaluated. Primary human retinal microvascular endothelial cells (hRMECs) were exposed to high glucose (HG; 25 mM) or pro-inflammatory cytokines IL-1β and TNF-α (10 ng/mL each) or both before assessing connexin43 expression. Additionally, connexin43, glial fibrillary acidic protein (GFAP), and plasmalemma vesicular associated protein (PLVAP) were labeled in wild-type (C57BL/6), Akita (diabetic), and Akimba (DR) mouse retinas. Finally, connexin43 and GFAP expression in donor retinas with confirmed DR was compared to age-matched controls. Co-application of HG and cytokines increased connexin43 expression in hRMECs in line with results seen in mice, with no significant difference in connexin43 or GFAP expression in Akita but higher expression in Akimba compared to wild-type mice. On PLVAP-positive vessels, connexin43 was higher in Akimba but unchanged in Akita compared to wild-type mice. Connexin43 expression appeared higher in donor retinas with confirmed DR compared to age-matched controls, similar to the distribution seen in Akimba mice and correlating with the in vitro results. Although connexin43 expression seems reduced in diabetes, hyperglycemia and inflammation present in the pathology of DR seem to increase connexin43 expression, suggesting a causal role of connexin43 channels in the disease progression.
Collapse
Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Jie Zhang
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Nicolette Binz
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth 6009, Western Australia, Australia.
| | - Monica L Acosta
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Elizabeth Rakoczy
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth 6009, Western Australia, Australia.
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| |
Collapse
|
19
|
Kim Y, Griffin JM, Nor MNM, Zhang J, Freestone PS, Danesh-Meyer HV, Rupenthal ID, Acosta M, Nicholson LFB, O'Carroll SJ, Green CR. Tonabersat Prevents Inflammatory Damage in the Central Nervous System by Blocking Connexin43 Hemichannels. Neurotherapeutics 2017; 14:1148-1165. [PMID: 28560708 PMCID: PMC5722754 DOI: 10.1007/s13311-017-0536-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The cis benzopyran compound tonabersat (SB-220453) has previously been reported to inhibit connexin26 expression in the brain by attenuating the p38-mitogen-activated protein kinase pathway. We show here that tonabersat directly inhibits connexin43 hemichannel opening. Connexin43 hemichannels have been called "pathological pores" based upon their role in secondary lesion spread, edema, inflammation, and neuronal loss following central nervous system injuries, as well as in chronic inflammatory disease. Both connexin43 hemichannels and pannexin channels released adenosine triphosphate (ATP) during ischemia in an in vitro ischemia model, but only connexin43 hemichannels contributed to ATP release during reperfusion. Tonabersat inhibited connexin43 hemichannel-mediated ATP release during both ischemia and reperfusion phases, with direct channel block confirmed using electrophysiology. Tonabersat also reduced connexin43 gap junction coupling in vitro, but only at higher concentrations, with junctional plaques internalized and degraded via the lysosomal pathway. Systemic delivery of tonabersat in a rat bright-light retinal damage model (a model for dry age-related macular degeneration) resulted in significantly improved functional outcomes assessed using electroretinography. Tonabersat also prevented thinning of the retina, especially the outer nuclear layer and choroid, assessed using optical coherence tomography. We conclude that tonabersat, already given orally to over 1000 humans in clinical trials (as a potential treatment for, and prophylactic treatment of, migraine because it was thought to inhibit cortical spreading depression), is a connexin hemichannel inhibitor and may have the potential to be a novel treatment of central nervous system injury and chronic neuroinflammatory disease.
Collapse
Affiliation(s)
- Yeri Kim
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Jarred M Griffin
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Mohd N Mat Nor
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- School of Optometry and Vision Science, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- Faculty of Medicine, University Sultan Zainal Abidin, Kuala Terengganu, Malaysia
| | - Jie Zhang
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Peter S Freestone
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Helen V Danesh-Meyer
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Ilva D Rupenthal
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- Buchanan Ocular Therapeutics Unit, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Monica Acosta
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
- School of Optometry and Vision Science, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Louise F B Nicholson
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Simon J O'Carroll
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Colin R Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand.
- New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand.
| |
Collapse
|
20
|
Mao Y, Nguyen T, Tonkin RS, Lees JG, Warren C, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Characterisation of Peptide5 systemic administration for treating traumatic spinal cord injured rats. Exp Brain Res 2017; 235:3033-3048. [PMID: 28725925 DOI: 10.1007/s00221-017-5023-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/03/2017] [Indexed: 11/27/2022]
Abstract
Systemic administration of a Connexin43 mimetic peptide, Peptide5, has been shown to reduce secondary tissue damage and improve functional recovery after spinal cord injury (SCI). This study investigated safety measures and potential off-target effects of Peptide5 systemic administration. Rats were subjected to a mild contusion SCI using the New York University impactor. One cohort was injected intraperitoneally with a single dose of fluorescently labelled Peptide5 and euthanised at 2 or 4 h post-injury for peptide distribution analysis. A second cohort received intraperitoneal injections of Peptide5 or a scrambled peptide and was culled at 8 or 24 h post-injury for the analysis of connexin proteins and systemic cytokine profile. We found that Peptide5 did not cross the blood-spinal cord barrier in control animals, but reached the lesion area in the spinal cord-injured animals without entering non-injured tissue. There was no evidence that the systemic administration of Peptide5 modulates Connexin43 protein expression or hemichannel closure in the heart and lung tissue of SCI animals. The expression levels of other major connexin proteins including Connexin30 in astrocytes, Connexin36 in neurons and Connexin47 in oligodendrocytes were also unaltered by systemic delivery of Peptide5 in either the injured or non-injured spinal cords. In addition, systemic delivery of Peptide5 had no significant effect on the plasma levels of cytokines, chemokines or growth factors. These data indicate that the systemic delivery of Peptide5 is unlikely to cause any off-target or adverse effects and may thus be a safe treatment option for traumatic SCI.
Collapse
Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Ryan S Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Justin G Lees
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Caitlyn Warren
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Louise F B Nicholson
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Colin R Green
- Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Catherine A Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia.
| |
Collapse
|
21
|
Mao Y, Tonkin RS, Nguyen T, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Systemic Administration of Connexin43 Mimetic Peptide Improves Functional Recovery after Traumatic Spinal Cord Injury in Adult Rats. J Neurotrauma 2017; 34:707-719. [DOI: 10.1089/neu.2016.4625] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Ryan S. Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Simon J. O'Carroll
- Department of Anatomy and Medical Imaging and the Centre for Brain Research, University of Auckland, Grafton, Auckland, New Zealand
| | - Louise F. B. Nicholson
- Department of Anatomy and Medical Imaging and the Centre for Brain Research, University of Auckland, Grafton, Auckland, New Zealand
| | - Colin R. Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Catherine A. Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
22
|
Choi SR, Roh DH, Yoon SY, Kwon SG, Choi HS, Han HJ, Beitz AJ, Lee JH. Astrocyte sigma-1 receptors modulate connexin 43 expression leading to the induction of below-level mechanical allodynia in spinal cord injured mice. Neuropharmacology 2016; 111:34-46. [PMID: 27567941 DOI: 10.1016/j.neuropharm.2016.08.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/21/2016] [Accepted: 08/23/2016] [Indexed: 01/13/2023]
Abstract
We have previously shown using a spinal cord injury (SCI) model that gap junctions contribute to the early spread of astrocyte activation in the lumbar spinal cord and that this astrocyte communication plays critical role in the induction of central neuropathic pain. Sigma-1 receptors (Sig-1Rs) have been implicated in spinal astrocyte activation and the development of peripheral neuropathic pain, yet their contribution to central neuropathic pain remains unknown. Thus, we investigated whether SCI upregulates spinal Sig-1Rs, which in turn increase the expression of the astrocytic gap junction protein, connexin 43 (Cx43) leading to the induction of central neuropathic pain. A thoracic spinal cord hemisection significantly increased both astrocyte activation and Cx43 expression in lumbar dorsal horn. Sig-1Rs were also increased in lumbar dorsal horn astrocytes, but not neurons or microglia. Intrathecal injection of an astrocyte metabolic inhibitor (fluorocitrate); a gap junction/hemichannel blocker (carbenoxolone); or a Cx43 mimetic peptide (43Gap26) significantly reduced SCI-induced bilateral below-level mechanical allodynia. Blockade of Sig-1Rs with BD1047 during the induction phase of pain significantly suppressed the SCI-induced development of mechanical allodynia, astrocyte activation, increased expression of Cx43 in both total and membrane levels, and increased association of Cx43 with Sig-1R. However, SCI did not change the expression of oligodendrocyte (Cx32) or neuronal (Cx36) gap junction proteins. These findings demonstrate that SCI activates astrocyte Sig-1Rs leading to increases in the expression of the gap junction protein, Cx43 and astrocyte activation in the lumbar dorsal horn, and ultimately contribute to the induction of bilateral below-level mechanical allodynia.
Collapse
Affiliation(s)
- Sheu-Ran Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Dae-Hyun Roh
- Department of Maxillofacial Tissue Regeneration and Research Center for Tooth and Periodontal Tissue Regeneration, School of Dentistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Seo-Yeon Yoon
- Pain Cognitive Function Research Center, Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Soon-Gu Kwon
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Hoon-Seong Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Ho-Jae Han
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Alvin J Beitz
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA
| | - Jang-Hern Lee
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea.
| |
Collapse
|
23
|
Connexin43 in retinal injury and disease. Prog Retin Eye Res 2016; 51:41-68. [DOI: 10.1016/j.preteyeres.2015.09.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/25/2015] [Accepted: 09/27/2015] [Indexed: 12/26/2022]
|
24
|
Kim Y, Davidson JO, Gunn KC, Phillips AR, Green CR, Gunn AJ. Role of Hemichannels in CNS Inflammation and the Inflammasome Pathway. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 104:1-37. [DOI: 10.1016/bs.apcsb.2015.12.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
25
|
Rodriguez-Jimenez FJ, Alastrue-Agudo A, Stojkovic M, Erceg S, Moreno-Manzano V. Connexin 50 Expression in Ependymal Stem Progenitor Cells after Spinal Cord Injury Activation. Int J Mol Sci 2015; 16:26608-18. [PMID: 26561800 PMCID: PMC4661840 DOI: 10.3390/ijms161125981] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/26/2015] [Accepted: 10/30/2015] [Indexed: 12/28/2022] Open
Abstract
Ion channels included in the family of Connexins (Cx) help to control cell proliferation and differentiation of neuronal progenitors. Here we explored the role of Connexin 50 (Cx50) in cell fate modulation of adult spinal cord derived neural precursors located in the ependymal canal (epSPC). epSPC from non-injured animals showed high expression levels of Cx50 compared to epSPC from animals with spinal cord injury (SCI) (epSPCi). When epSPC or epSPCi were induced to spontaneously differentiate in vitro we found that Cx50 favors glial cell fate, since higher expression levels, endogenous or by over-expression of Cx50, augmented the expression of the astrocyte marker GFAP and impaired the neuronal marker Tuj1. Cx50 was found in both the cytoplasm and nucleus of glial cells, astrocytes and oligodendrocyte-derived cells. Similar expression patterns were found in primary cultures of mature astrocytes. In addition, opposite expression profile for nuclear Cx50 was observed when epSPC and activated epSPCi were conducted to differentiate into mature oligodendrocytes, suggesting a different role for this ion channel in spinal cord beyond cell-to-cell communication. In vivo detection of Cx50 by immunohistochemistry showed a defined location in gray matter in non-injured tissues and at the epicenter of the injury after SCI. epSPCi transplantation, which accelerates locomotion regeneration by a neuroprotective effect after acute SCI is associated with a lower signal of Cx50 within the injured area, suggesting a minor or detrimental contribution of this ion channel in spinal cord regeneration by activated epSPCi.
Collapse
Affiliation(s)
| | - Ana Alastrue-Agudo
- Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
| | - Miodrag Stojkovic
- Spebo Medical, 16000 Leskovac, Serbia.
- Human Genetics, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia.
| | - Slaven Erceg
- Stem Cell Therapies in Neurodegenerative Diseases Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
| | - Victoria Moreno-Manzano
- Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
| |
Collapse
|
26
|
Jeon YH, Youn DH. Spinal Gap Junction Channels in Neuropathic Pain. Korean J Pain 2015; 28:231-5. [PMID: 26495077 PMCID: PMC4610936 DOI: 10.3344/kjp.2015.28.4.231] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 06/17/2015] [Accepted: 06/25/2015] [Indexed: 11/26/2022] Open
Abstract
Damage to peripheral nerves or the spinal cord is often accompanied by neuropathic pain, which is a complex, chronic pain state. Increasing evidence indicates that alterations in the expression and activity of gap junction channels in the spinal cord are involved in the development of neuropathic pain. Thus, this review briefly summarizes evidence that regulation of the expression, coupling, and activity of spinal gap junction channels modulates pain signals in neuropathic pain states induced by peripheral nerve or spinal cord injury. We particularly focus on connexin 43 and pannexin 1 because their regulation vastly attenuates symptoms of neuropathic pain. We hope that the study of gap junction channels eventually leads to the development of a suitable treatment tool for patients with neuropathic pain.
Collapse
Affiliation(s)
- Young Hoon Jeon
- Department of Anesthesiology and Pain Medicine, School of Dentistry, Kyungpook National University, Daegu, Korea
| | - Dong Ho Youn
- Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| |
Collapse
|
27
|
Decrock E, De Bock M, Wang N, Bultynck G, Giaume C, Naus CC, Green CR, Leybaert L. Connexin and pannexin signaling pathways, an architectural blueprint for CNS physiology and pathology? Cell Mol Life Sci 2015; 72:2823-51. [PMID: 26118660 PMCID: PMC11113968 DOI: 10.1007/s00018-015-1962-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 02/06/2023]
Abstract
The central nervous system (CNS) is composed of a highly heterogeneous population of cells. Dynamic interactions between different compartments (neuronal, glial, and vascular systems) drive CNS function and allow to integrate and process information as well as to respond accordingly. Communication within this functional unit, coined the neuro-glio-vascular unit (NGVU), typically relies on two main mechanisms: direct cell-cell coupling via gap junction channels (GJCs) and paracrine communication via the extracellular compartment, two routes to which channels composed of transmembrane connexin (Cx) or pannexin (Panx) proteins can contribute. Multiple isoforms of both protein families are present in the CNS and each CNS cell type is characterized by a unique Cx/Panx portfolio. Over the last two decades, research has uncovered a multilevel platform via which Cxs and Panxs can influence different cellular functions within a tissue: (1) Cx GJCs enable a direct cell-cell communication of small molecules, (2) Cx hemichannels and Panx channels can contribute to autocrine/paracrine signaling pathways, and (3) different structural domains of these proteins allow for channel-independent functions, such as cell-cell adhesion, interactions with the cytoskeleton, and the activation of intracellular signaling pathways. In this paper, we discuss current knowledge on their multifaceted contribution to brain development and to specific processes in the NGVU, including synaptic transmission and plasticity, glial signaling, vasomotor control, and blood-brain barrier integrity in the mature CNS. By highlighting both physiological and pathological conditions, it becomes evident that Cxs and Panxs can play a dual role in the CNS and that an accurate fine-tuning of each signaling mechanism is crucial for normal CNS physiology.
Collapse
Affiliation(s)
- Elke Decrock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Louvain, Belgium
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France
- University Pierre et Marie
Curie, ED, N°158, 75005 Paris, France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Colin R. Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| |
Collapse
|
28
|
Manich G, Cabezón I, Camins A, Pallàs M, Liberski PP, Vilaplana J, Pelegrí C. Clustered granules present in the hippocampus of aged mice result from a degenerative process affecting astrocytes and their surrounding neuropil. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9690. [PMID: 25070375 PMCID: PMC4150886 DOI: 10.1007/s11357-014-9690-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 07/13/2014] [Indexed: 06/03/2023]
Abstract
Clusters of pathological granular structures appear and progressively increase in number with age in the hippocampus of several mice strains, markedly in the senescence-accelerated mouse prone 8 mice. In the present work, we performed an ultrastructural study of these granules paying special attention to the first stages of their formation, which have not been previously explored. The analysis of the immature granules allowed concluding that granules are not simple accumulations of molecular waste but the result of a degenerative process involving principally astrocytic processes, although nearby neuronal structures can be also affected. The granule generation includes the instability of the plasmatic membranes and the appearance of abnormal membranous structures that form intracellular bubbles or blebs of variable sizes and irregular shapes. These structures and some organelles degenerate producing some membranous fragments, and an assembly process of the resulting fragments generates the dense-core nucleus of the mature granule. Moreover, we found out that the neo-epitope recently described in the mature granules and localised abundantly in the membranous fragments of their dense-core nucleus emerges in the first stages of the granule formation. On the other hand, with this study, we increase the evidences that each cluster of granules is formed by the granules comprised in one astrocyte. A better knowledge of the causes of the granule formation and the function of the neo-epitope will help in both the interpretation of the physiological significance of the granules and their contribution to the degenerating processes in aging brain.
Collapse
Affiliation(s)
- Gemma Manich
- />Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Itsaso Cabezón
- />Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Antoni Camins
- />Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
- />Centros de Biomedicina en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| | - Mercè Pallàs
- />Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Institut de Biomedicina (IBUB), Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
- />Centros de Biomedicina en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| | - Pawel P. Liberski
- />Department of Molecular Pathology and Neuropathology, Medical University of Lodz, Lodz, Poland
| | - Jordi Vilaplana
- />Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
- />Centros de Biomedicina en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| | - Carme Pelegrí
- />Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
- />Centros de Biomedicina en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| |
Collapse
|
29
|
Goncharenko K, Eftekharpour E, Velumian AA, Carlen PL, Fehlings MG. Changes in gap junction expression and function following ischemic injury of spinal cord white matter. J Neurophysiol 2014; 112:2067-75. [PMID: 25080569 DOI: 10.1152/jn.00037.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gap junctions are widely present in spinal cord white matter; however, their role in modulating the dynamics of axonal dysfunction remains largely unexplored. We hypothesized that inhibition of gap junctions reduces the loss of axonal function during oxygen and glucose deprivation (OGD). The functional role of gap junctions was assessed by electrophysiological recordings of compound action potentials (CAPs) in Wistar rat spinal cord slices with the sucrose gap technique. The in vitro slices were subjected to 30-min OGD. Gap junction connexin (Cx) mRNA expression was determined by qPCR and normalized to β-actin. A 30-min OGD resulted in reduction of CAPs to 14.8 ± 4.6% of their pre-OGD amplitude (n = 5). In the presence of gap junction blockers carbenoxolone (Cbx; 100 μM) and 1-octanol (Oct; 300 μM), the CAP reduction in OGD was to only 35.7 ± 5.7% of pre-OGD amplitude in Cbx (n = 9) and to 37.4 ± 8.9% of pre-OGD amplitude in Oct (n = 10). Both drugs also noticeably prolonged the half-decline time of CAP amplitudes in OGD from 6.0 min in no-drug conditions to 9.6 min in the presence of Cbx and to 7.7 min in the presence of Oct, suggesting that blocking gap junctions reduces conduction loss during OGD. With application of Cbx and Oct in the setting of OGD, expression of Cx30 and Cx43 mRNA was downregulated. Our data provide new insights into the role of gap junctions in white matter ischemia and reveal the necessity of a cautious approach in determining detrimental or beneficial effects of gap junction blockade in white matter ischemia.
Collapse
Affiliation(s)
- Karina Goncharenko
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and
| | - Eftekhar Eftekharpour
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada
| | - Alexander A Velumian
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Peter L Carlen
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Departments of Physiology and
| | - Michael G Fehlings
- Division of Neurosurgery and Division of Genetics and Development, Toronto Western Research Institute, Krembil Neuroscience Centre, University Health Network and University of Toronto, Toronto, Ontario, Canada; Surgery, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
30
|
O'Carroll SJ, Becker DL, Davidson JO, Gunn AJ, Nicholson LFB, Green CR. The use of connexin-based therapeutic approaches to target inflammatory diseases. Methods Mol Biol 2014; 1037:519-46. [PMID: 24029957 DOI: 10.1007/978-1-62703-505-7_31] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Alterations in Connexin43 (Cx43) expression levels have been shown to play a role in inflammatory processes including skin wounding and neuroinflammation. Cx43 protein levels increase following a skin wound and can inhibit wound healing. Increased Cx43 has been observed following stroke, epilepsy, ischemia, optic nerve damage, and spinal cord injury with gap junctional communication and hemichannel opening leading to increased secondary damage via the inflammatory response. Connexin43 modulation has been identified as a potential target for protection and repair in neuroinflammation and skin wound repair. This review describes the use of a Cx43 specific antisense oligonucleotide (Cx43 AsODN) and peptide mimetics of the connexin extracellular loop domain to modulate Cx43 expression and/or function in inflammatory disorders of the skin and central nervous system. An overview of the role of connexin43 in inflammatory conditions, how antisense and peptide have allowed us to elucidate the role of Cx43 in these diseases, create models of diseases to test interventions and their potential for use clinically or in current clinical trials is presented. Antisense oligonucleotides are applied topically and have been used to improve wound healing following skin injury. They have also been used to develop ex vivo models of neuroinflammatory diseases that will allow testing of intervention strategies. The connexin mimetic peptides have shown potential in a number of neuroinflammatory disorders in ex vivo models as well as in vivo when delivered directly to the injury site or when delivered systemically.
Collapse
Affiliation(s)
- Simon J O'Carroll
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | | | | | | | | | | |
Collapse
|
31
|
De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
Collapse
Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| |
Collapse
|
32
|
Effect of VEGF and CX43 on the promotion of neurological recovery by hyperbaric oxygen treatment in spinal cord-injured rats. Spine J 2014; 14:119-27. [PMID: 24183749 DOI: 10.1016/j.spinee.2013.06.084] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 05/13/2013] [Accepted: 06/24/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Spinal cord injury (SCI) is a serious health issue that may result in high health care costs, with additional social and psychological burdens. Hyperbaric oxygen (HBO) treatment has been found to be beneficial for neurological recovery; however, the underlying mechanisms are yet to be characterized. PURPOSE The aim of this study was to investigate the mechanisms of HBO treatment in SCI by measuring the expression levels of vascular endothelial growth factor (VEGF) and Connexin43 (CX43) in the injured spinal cord tissue. STUDY DESIGN/SETTING An experiment animal study of rats undergoing SCI and HBO treatment. METHODS The spinal cord injury model was established in rats, which were randomly divided into the following four groups: (1) the sham-operated group (SH), (2) the sham-operated and hyperbaric oxygen treatment group (SH+HBO), (3) the spinal cord injury group (SCI), and (4) the spinal cord injury and hyperbaric oxygen treatment group (SCI+HBO). For groups of SH+HBO and SCI+HBO, the animals received 1 hour of HBO at 2.0 ATA in 100% O2 twice per day for 3 days and then daily for the following days consecutively after surgery. After operation, neurological assessments were performed, the spinal cord tissue samples were harvested for histopathological evaluation, Western blot and real-time polymerase chain reaction analysis. RESULTS The Basso-Bettie-Bresnahan scores were significantly improved in the SCI+HBO group compared with the SCI group on the postoperative 7th and 14th days. The histology scores were significantly decreased by HBO treatment compared with that in the SCI group on the postoperative 3rd, 7th, and 14th days. Western blot analysis and real-time polymerase chain reaction revealed that the expression level of vascular endothelial growth factor (VEGF) in the SCI+HBO group was significantly increased compared with the SCI group. The protein expression level of CX43 and its mRNA level in the SCI+HBO group were significantly decreased on the postoperative 3rd and 7th days, whereas its expression was significantly increased by HBO treatment on the postoperative 14th day compared with the SCI group. CONCLUSIONS HBO treatment improved neurological recovery when applied after SCI. The expression level changes of VEGF and CX43 may contribute to the further understanding on the molecular mechanisms of HBO treatment on SCI.
Collapse
|
33
|
Ji RR, Berta T, Nedergaard M. Glia and pain: is chronic pain a gliopathy? Pain 2013; 154 Suppl 1:S10-S28. [PMID: 23792284 PMCID: PMC3858488 DOI: 10.1016/j.pain.2013.06.022] [Citation(s) in RCA: 815] [Impact Index Per Article: 74.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 05/23/2013] [Accepted: 06/12/2013] [Indexed: 12/22/2022]
Abstract
Activation of glial cells and neuro-glial interactions are emerging as key mechanisms underlying chronic pain. Accumulating evidence has implicated 3 types of glial cells in the development and maintenance of chronic pain: microglia and astrocytes of the central nervous system (CNS), and satellite glial cells of the dorsal root and trigeminal ganglia. Painful syndromes are associated with different glial activation states: (1) glial reaction (ie, upregulation of glial markers such as IBA1 and glial fibrillary acidic protein (GFAP) and/or morphological changes, including hypertrophy, proliferation, and modifications of glial networks); (2) phosphorylation of mitogen-activated protein kinase signaling pathways; (3) upregulation of adenosine triphosphate and chemokine receptors and hemichannels and downregulation of glutamate transporters; and (4) synthesis and release of glial mediators (eg, cytokines, chemokines, growth factors, and proteases) to the extracellular space. Although widely detected in chronic pain resulting from nerve trauma, inflammation, cancer, and chemotherapy in rodents, and more recently, human immunodeficiency virus-associated neuropathy in human beings, glial reaction (activation state 1) is not thought to mediate pain sensitivity directly. Instead, activation states 2 to 4 have been demonstrated to enhance pain sensitivity via a number of synergistic neuro-glial interactions. Glial mediators have been shown to powerfully modulate excitatory and inhibitory synaptic transmission at presynaptic, postsynaptic, and extrasynaptic sites. Glial activation also occurs in acute pain conditions, and acute opioid treatment activates peripheral glia to mask opioid analgesia. Thus, chronic pain could be a result of "gliopathy," that is, dysregulation of glial functions in the central and peripheral nervous system. In this review, we provide an update on recent advances and discuss remaining questions.
Collapse
Affiliation(s)
- Ru-Rong Ji
- Department of Anesthesiology and Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Temugin Berta
- Department of Anesthesiology and Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, USA
| |
Collapse
|
34
|
Castejón OJ. Electron microscopy of astrocyte changes and subtypes in traumatic human edematous cerebral cortex: a review. Ultrastruct Pathol 2013; 37:417-24. [PMID: 24134799 DOI: 10.3109/01913123.2013.831157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The astrocyte subtypes in moderate and severe human brain trauma complicated with subdural hematoma or hygroma are described. Clear and dense edematous and hypertrophic reactive astrocytes are distinguished in severe vasogenic brain edema. Swollen perineuronal astrocytes appear compressing and indenting dark, degenerated pyramidal and nonpyramidal nerve cells. Glycogen-depleted and glycogen-rich astrocytes also are seen. Reactive hypertrophic astrocytes exhibit increased amounts of dilated smooth and rough endoplasmic reticulum, microtubules, and gliofilaments. Perisynaptic astrocyte ensheathments of neuropil synaptic contacts are lost, and the perivascular astrocyte end-feet appear dissociated from the capillary basement membrane. The interastrocytary gap junctions appear fragmented.
Collapse
Affiliation(s)
- Orlando J Castejón
- Biological Research Institute, "Drs. Orlando Castejón and Haydée Viloria de Castejón," Faculty of Medicine, Zulia University , Maracaibo , Venezuela
| |
Collapse
|
35
|
Connexin43 mimetic peptide is neuroprotective and improves function following spinal cord injury. Neurosci Res 2013; 75:256-67. [PMID: 23403365 DOI: 10.1016/j.neures.2013.01.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 12/07/2012] [Accepted: 01/13/2013] [Indexed: 12/29/2022]
Abstract
Connexin43 (Cx43) is a gap junction protein up-regulated after spinal cord injury and is involved in the on-going spread of secondary tissue damage. To test whether a connexin43 mimetic peptide (Peptide5) reduces inflammation and tissue damage and improves function in an in vivo model of spinal cord injury, rats were subjected to a 10g, 12.5mm weight drop injury at the vertebral level T10 using a MASCIS impactor. Vehicle or connexin43 mimetic peptide was delivered directly to the lesion via intrathecal catheter and osmotic mini-pump for up to 24h after injury. Treatment with Peptide5 led to significant improvements in hindlimb function as assessed using the Basso-Beattie-Bresnahan scale. Peptide5 caused a reduction in Cx43 protein, increased Cx43 phosphorylation and decreased levels of TNF-α and IL-1β as assessed by Western blotting. Immunohistochemistry of tissue sections 5 weeks after injury showed reductions in astrocytosis and activated microglia as well as an increase in motor neuron survival. These results show that administration of a connexin mimetic peptide reduces secondary tissue damage after spinal cord injury by reducing gliosis and cytokine release and indicate the clinical potential for mimetic peptides in the treatment of spinal cord patients.
Collapse
|
36
|
Chen MJ, Kress B, Han X, Moll K, Peng W, Ji RR, Nedergaard M. Astrocytic CX43 hemichannels and gap junctions play a crucial role in development of chronic neuropathic pain following spinal cord injury. Glia 2012; 60:1660-70. [PMID: 22951907 DOI: 10.1002/glia.22384] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 06/14/2012] [Indexed: 12/31/2022]
Abstract
Chronic neuropathic pain is a frequent consequence of spinal cord injury (SCI). Yet despite recent advances, upstream releasing mechanisms and effective therapeutic options remain elusive. Previous studies have demonstrated that SCI results in excessive ATP release to the peritraumatic regions and that purinergic signaling, among glial cells, likely plays an essential role in facilitating inflammatory responses and nociceptive sensitization. We sought to assess the role of connexin 43 (Cx43) as a mediator of CNS inflammation and chronic pain. To determine the extent of Cx43 involvement in chronic pain, a weight-drop SCI was performed on transgenic mice with Cx43/Cx30 deletions. SCI induced robust and persistent neuropathic pain including heat hyperalgesia and mechanical allodynia in wild-type control mice, which developed after 4 weeks and was maintained after 8 weeks. Notably, SCI-induced heat hyperalgesia and mechanical allodynia were prevented in transgenic mice with Cx43/Cx30 deletions, but fully developed in transgenic mice with only Cx30 deletion. SCI-induced gliosis, detected as upregulation of glial fibrillary acidic protein in the spinal cord astrocytes at different stages of the injury, was also reduced in the knockout mice with Cx43/Cx30 deletions, when compared with littermate controls. In comparison, a standard regimen of post-SCI treatment of minocycline attenuated neuropathic pain to a significantly lesser degree than Cx43 deletion. These findings suggest Cx43 is critically linked to the development of central neuropathic pain following acute SCI. Since Cx43/Cx30 is expressed by astrocytes, these findings also support an important role of astrocytes in the development of chronic pain.
Collapse
Affiliation(s)
- Michael J Chen
- Department of Neurosurgery, Center for Translational Neuromedicine, University of Rochester Medical School, Rochester, New York, USA
| | | | | | | | | | | | | |
Collapse
|
37
|
Gwak YS, Kang J, Unabia GC, Hulsebosch CE. Spatial and temporal activation of spinal glial cells: role of gliopathy in central neuropathic pain following spinal cord injury in rats. Exp Neurol 2011; 234:362-72. [PMID: 22036747 DOI: 10.1016/j.expneurol.2011.10.010] [Citation(s) in RCA: 199] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 10/05/2011] [Accepted: 10/13/2011] [Indexed: 01/27/2023]
Abstract
In the spinal cord, neuron and glial cells actively interact and contribute to neurofunction. Surprisingly, both cell types have similar receptors, transporters and ion channels and also produce similar neurotransmitters and cytokines. The neuroanatomical and neurochemical similarities work synergistically to maintain physiological homeostasis in the normal spinal cord. However, in trauma or disease states, spinal glia become activated, dorsal horn neurons become hyperexcitable contributing to sensitized neuronal-glial circuits. The maladaptive spinal circuits directly affect synaptic excitability, including activation of intracellular downstream cascades that result in enhanced evoked and spontaneous activity in dorsal horn neurons with the result that abnormal pain syndromes develop. Recent literature reported that spinal cord injury produces glial activation in the dorsal horn; however, the majority of glial activation studies after SCI have focused on transient and/or acute time points, from a few hours to 1 month, and peri-lesion sites, a few millimeters rostral and caudal to the lesion site. In addition, thoracic spinal cord injury produces activation of astrocytes and microglia that contributes to dorsal horn neuronal hyperexcitability and central neuropathic pain in above-level, at-level and below-level segments remote from the lesion in the spinal cord. The cellular and molecular events of glial activation are not simple events, rather they are the consequence of a combination of several neurochemical and neurophysiological changes following SCI. The ionic imbalances, neuroinflammation and alterations of cell cycle proteins after SCI are predominant components for neuroanatomical and neurochemical changes that result in glial activation. More importantly, SCI induced release of glutamate, proinflammatory cytokines, ATP, reactive oxygen species (ROS) and neurotrophic factors trigger activation of postsynaptic neuron and glial cells via their own receptors and channels that, in turn, contribute to neuronal-neuronal and neuronal-glial interaction as well as microglia-astrocytic interactions. However, a systematic review of temporal and spatial glial activation following SCI has not been done. In this review, we describe time and regional dependence of glial activation and describe activation mechanisms in various SCI models in rats. These data are placed in the broader context of glial activation mechanisms and chronic pain states. Our work in the context of work by others in SCI models demonstrates that dysfunctional glia, a condition called "gliopathy", is a key contributor in the underlying cellular mechanisms contributing to neuropathic pain.
Collapse
Affiliation(s)
- Young S Gwak
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch at Galveston, TX 77555, USA.
| | | | | | | |
Collapse
|
38
|
Wu A, Green CR, Rupenthal ID, Moalem-Taylor G. Role of gap junctions in chronic pain. J Neurosci Res 2011; 90:337-45. [DOI: 10.1002/jnr.22764] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/15/2011] [Accepted: 07/15/2011] [Indexed: 11/10/2022]
|
39
|
Kerr NM, Johnson CS, Green CR, Danesh-Meyer HV. Gap junction protein connexin43 (GJA1) in the human glaucomatous optic nerve head and retina. J Clin Neurosci 2010; 18:102-8. [PMID: 20934339 DOI: 10.1016/j.jocn.2010.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Accepted: 06/09/2010] [Indexed: 11/19/2022]
Abstract
Primary open angle glaucoma is characterised by the progressive and irreversible death of retinal ganglion cells. Experimental evidence suggests that the initial site of injury to the retinal ganglion cell is at or near the lamina cribrosa or in the peripapillary retina. However, the mediators of axonal injury remain poorly understood. The purpose of this study was to investigate the expression of the gap junction protein connexin43 (GJA1) in the human glaucomatous optic nerve head and retina as a potential mediator of axonal injury. Using affinity isolated polyclonal antibodies to the C-terminal segment of human connexin43, the expression of connexin43 was determined in post-mortem human eyes with primary open angle glaucoma and age-matched controls. In normal eyes, connexin43 was present on glial fibrillary acidic protein (GFAP)-positive astrocytes in the retinal ganglion cell layer and optic nerve head. In glaucomatous eyes, increased connexin43 immunoreactivity was observed at the level of the lamina cribrosa and in the peripapillary and mid-peripheral retina in association with glial activation. This novel finding may suggest that gap junction communication is a potential mediator of retinal ganglion cell injury in glaucoma.
Collapse
Affiliation(s)
- Nathan M Kerr
- Department of Ophthalmology, University of Auckland, Faculty of Medical and Health Sciences, Private Bag 92019, Auckland 1142, New Zealand
| | | | | | | |
Collapse
|
40
|
Role of connexin43 in central nervous system injury. Exp Neurol 2010; 225:250-61. [DOI: 10.1016/j.expneurol.2010.07.014] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 06/09/2010] [Accepted: 07/15/2010] [Indexed: 01/03/2023]
|
41
|
Nesic O, Guest JD, Zivadinovic D, Narayana PA, Herrera JJ, Grill RJ, Mokkapati VUL, Gelman BB, Lee J. Aquaporins in spinal cord injury: the janus face of aquaporin 4. Neuroscience 2010; 168:1019-35. [PMID: 20109536 PMCID: PMC2885549 DOI: 10.1016/j.neuroscience.2010.01.037] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/16/2010] [Accepted: 01/19/2010] [Indexed: 02/07/2023]
Abstract
Although malfunction of spinal cord water channels (aquaporins, AQP) likely contributes to severe disturbances in ion/water homeostasis after spinal cord injury (SCI), their roles are still poorly understood. Here we report and discuss the potential significance of changes in the AQP4 expression in human SCI that generates glial fibrillary acidic protein (GFAP)-labeled astrocytes devoid of AQP4, and GFAP-labeled astroglia that overexpress AQP4. We used a rat model of contusion SCI to study observed changes in human SCI. AQP4-negative astrocytes are likely generated during the process of SCI-induced replacement of lost astrocytes, but their origin and role in SCI remains to be investigated. We found that AQP4-overexpression is likely triggered by hypoxia. Our transcriptional profiling of injured rat cords suggests that elevated AQP4-mediated water influx accompanies increased uptake of chloride and potassium ions which represents a protective astrocytic reaction to hypoxia. However, unbalanced water intake also results in astrocytic swelling that can contribute to motor impairment, but likely only in milder injuries. In severe rat SCI, a low abundance of AQP4-overexpressing astrocytes was found during the motor recovery phase. Our results suggest that severe rat contusion SCI is a better model to analyze AQP4 functions after SCI. We found that AQP4 increases in the chronic post-injury phase are associated with the development of pain-like behavior in SCI rats, while possible mechanisms underlying pain development may involve astrocytic swelling-induced glutamate release. In contrast, the formation and size of fluid-filled cavities occurring later after SCI does not appear to be affected by the extent of increased AQP4 levels. Therefore, the effect of therapeutic interventions targeting AQP4 will depend not only on the time interval after SCI or animal models, but also on the balance between protective role of increased AQP4 in hypoxia and deleterious effects of ongoing astrocytic swelling.
Collapse
Affiliation(s)
- O Nesic
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Zhang J, O'Carroll SJ, Wu A, Nicholson LFB, Green CR. A model for ex vivo spinal cord segment culture--a tool for analysis of injury repair strategies. J Neurosci Methods 2010; 192:49-57. [PMID: 20654650 DOI: 10.1016/j.jneumeth.2010.07.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 06/18/2010] [Accepted: 07/11/2010] [Indexed: 11/28/2022]
Abstract
Most spinal cord injury research is undertaken using in vivo animal models but the extensive care associated with spinalized animals, inherent variability between animals, and complex surgeries makes alternative models especially valuable. Here we present a novel ex vivo model that enables culture of intact post-natal spinal cord segments for up to five days and the assessment of peripheral nerve grafting repair, enhanced with connexin43 antisense oligodeoxynucleotides (Cx43 AsODN), in this model. Down-regulating Cx43 expression with Cx43 AsODN in cultured spinal cord segments prevents cell death and inhibits inflammation spreading from the site of injury to neighbouring tissue, hence maintaining culture viability. Reduction in segment swelling and improvement in neuron survival were evident after Cx43 AsODN treatment. Furthermore, the combination of Cx43 AsODN with peripheral nerve graft implants into cultured spinal cords promoted axon sprouting from the spinal cord into the peripheral nerve graft. This ex vivo spinal cord segment culture model provides a valuable addition to tools currently available for spinal cord injury research.
Collapse
Affiliation(s)
- Jie Zhang
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
| | | | | | | | | |
Collapse
|
43
|
Giaume C, Koulakoff A, Roux L, Holcman D, Rouach N. Astroglial networks: a step further in neuroglial and gliovascular interactions. Nat Rev Neurosci 2010; 11:87-99. [DOI: 10.1038/nrn2757] [Citation(s) in RCA: 562] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
44
|
O'Carroll SJ, Alkadhi M, Nicholson LFB, Green CR. Connexin43 Mimetic Peptides Reduce Swelling, Astrogliosis, and Neuronal Cell Death after Spinal Cord Injury. ACTA ACUST UNITED AC 2009; 15:27-42. [DOI: 10.1080/15419060802014164] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
45
|
Cronin M, Anderson PN, Cook JE, Green CR, Becker DL. Blocking connexin43 expression reduces inflammation and improves functional recovery after spinal cord injury. Mol Cell Neurosci 2008; 39:152-60. [PMID: 18617007 DOI: 10.1016/j.mcn.2008.06.005] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 06/01/2008] [Accepted: 06/04/2008] [Indexed: 11/17/2022] Open
Abstract
After traumatic CNS injury, a cascade of secondary events expands the initial lesion. The gap-junction protein connexin43 (Cx43), which is transiently up-regulated, has been implicated in the spread of 'bystander' damage. We have used an antisense oligodeoxynucleotide (asODN) to suppress Cx43 up-regulation in two rat models of spinal cord injury. Within 24 h of compression injury, rats treated with Cx43-asODN scored higher than sense-ODN and vehicle-treated controls on behavioural tests of locomotion. Their spinal cords showed less swelling and tissue disruption, less up-regulation of astrocytic GFAP, and less extravasation of fluorescently-labelled bovine serum albumin and neutrophils. The locomotor improvement was sustained over at least 4 weeks. Following partial spinal cord transection, Cx43-asODN treatment reduced GFAP immunoreactivity, neutrophil recruitment, and the activity of OX42(+) microglia in and around the lesion site. Cx43 has many potential roles in the pathophysiology of CNS injury and may be a valuable target for therapeutic intervention.
Collapse
Affiliation(s)
- Michael Cronin
- Research Department of Cell and Developmental Biology, University College London, London, UK
| | | | | | | | | |
Collapse
|
46
|
Persistent Borna Disease Virus infection changes expression and function of astroglial gap junctions in vivo and in vitro. Brain Res 2007; 1184:316-32. [PMID: 18028885 DOI: 10.1016/j.brainres.2007.09.062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 09/23/2007] [Accepted: 09/24/2007] [Indexed: 11/21/2022]
Abstract
Neonatal Borna Disease Virus (BDV) infection of the Lewis rat brain leads to dentate gyrus (DG) degeneration, underlying mechanisms are not fully understood. Since astroglial gap junction (GJ) coupling is known to influence neurodegenerative processes, the question arose whether persistent BDV infection influences astroglial connexins (Cx) Cx43 and Cx30 in the hippocampal formation (HiF) of Lewis rats. RT-PCR and Western blot analysis of forebrain (FB) samples revealed a virus dependent reduction of both Cx types 8 but not 4 weeks post infection (p.i.). Immunohistochemistry revealed an increase of Cx43 in the DG and a decrease in the CA3 region 4 and 8 weeks p.i. Cx30, which was detectable only 8 weeks p.i., revealed a BDV dependent increase in DG and CA3 regions. BDV dependent astrogliosis as revealed by immunodetection of glial fibrillary acidic protein (GFAP) correlated not with astroglial connexin expression. With regard to functional coupling as revealed by scrape loading, BDV infection resulted in increased spreading of the GJ permeant dye Lucifer yellow in primary hippocampal astroglial cultures, and in increased expression of Cx43 and Cx30 as revealed by immunocytochemistry. In conclusion, persistent BDV infection of the Lewis rat brain leads to changes in astroglial Cx expression both in vivo and in vitro and of functional coupling in vitro. Distribution and time course of these changes suggest them to be a direct result of neurodegeneration in the DG and an indirect effect of neuronal deafferentiation in the CA3 region.
Collapse
|
47
|
Lee IH, Lindqvist E, Kiehn O, Widenfalk J, Olson L. Glial and neuronal connexin expression patterns in the rat spinal cord during development and following injury. J Comp Neurol 2005; 489:1-10. [PMID: 15977163 DOI: 10.1002/cne.20567] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Spinal cord injury induces a complex cascade of degenerative and remodeling events evolving over time. The possible roles of changed intercellular communication via gap junctions after spinal cord injury (SCI) have remained relatively unexplored. We investigated the temporospatial expression patterns of gap junctional genes and proteins, connexin 43 (Cx43), Cx36, and Cx32, by in situ hybridization and immunohistochemistry in the rat neonatal, adult normal, and adult injured spinal cord. Cx36 was strongly expressed in immature neurons, and levels declined markedly during development, whereas Cx43 and Cx32 persisted throughout adulthood. After a complete transection of the adult spinal cord, the levels of Cx43 mRNA and protein were up-regulated within hours, especially in gray matter rostral to the lesion, reaching over three times normal levels at 4 weeks postinjury. Cx43 immunoreactivity was seen primarily in astrocytes and rarely in microglia. In contrast, Cx36 and Cx32 mRNA and proteins were relatively sparse and unchanged after spinal cord injury along the entire axis of the spinal cord. Cx43 is the most abundant gap junctional protein in the adult CNS and has been shown to form channels between astrocytes as well as between astrocytes and oligodendrocytes. Long-term up-regulation of Cx43 in reactive astrocytes may be one critical component in the rearrangement of the local astroglial network following SCI.
Collapse
Affiliation(s)
- I-Hui Lee
- Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden.
| | | | | | | | | |
Collapse
|
48
|
Brand-Schieber E, Werner P, Iacobas DA, Iacobas S, Beelitz M, Lowery SL, Spray DC, Scemes E. Connexin43, the major gap junction protein of astrocytes, is down-regulated in inflamed white matter in an animal model of multiple sclerosis. J Neurosci Res 2005; 80:798-808. [PMID: 15898103 PMCID: PMC1226319 DOI: 10.1002/jnr.20474] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE), its animal model, involve inflammatory attack on central nervous system (CNS) white matter, leading to demyelination and axonal damage. Changes in astrocytic morphology and function are also prominent features of MS and EAE. Resting astrocytes form a network that is interconnected through gap junctions, composed mainly of connexin43 (Cx43) protein. Although astrocytic gap junctional connectivity is known to be altered in many CNS pathologies, little is known about Cx43 expression in inflammatory demyelinating disease. Therefore, we evaluated the expression of Cx43 in spinal cords of EAE mice compared with healthy controls. Lumbar ventral white matter areas were heavily infiltrated with CD11beta-immunoreactive monocytes, and within these infiltrated regions loss of Cx43 immunoreactivity was evident. These regions also showed axonal dystrophy, demonstrated by the abnormally dephosphorylated heavy-chain neurofilament proteins. Astrocytes in these Cx43-depleted lesions were strongly glial fibrillary acidic protein reactive. Significant loss (38%) of Cx43 protein in EAE mouse at the lumbar portion of spinal cords was confirmed by Western blot analysis. Decreased Cx43 transcript level was also observed on cDNA microarray analysis. In addition to changes in Cx43 expression, numerous other genes were altered, including those encoding adhesion and extracellular matrix proteins. Our data support the notion that, in addition to damage of myelinating glia, altered astrocyte connectivity is a prominent feature of inflammatory demyelination.
Collapse
|
49
|
Van Bockstaele EJ, Garcia-Hernandez F, Fox K, Alvarez VA, Williams JT. Expression of connexins during development and following manipulation of afferent input in the rat locus coeruleus. Neurochem Int 2004; 45:421-8. [PMID: 15145556 DOI: 10.1016/j.neuint.2003.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2003] [Revised: 08/25/2003] [Accepted: 08/28/2003] [Indexed: 10/26/2022]
Abstract
Synchronous activity of locus coeruleus (LC) neurons during early postnatal development is regulated, in part, by electrotonic coupling. Connexin (Cx) proteins that make up gap junction channels are localized to both neurons and glia in the LC during this period. In adult rats, however, synchrony exists only under certain experimental conditions. The expression of Cx proteins was examined using western blot analysis at several developmental time points. Immunoblot analysis revealed little to no expression of Cx26 while Cx32, Cx43 and Cx36 were present at all time points examined. A progressive increase in Cx43 was identified from the first postnatal week through adulthood. Immunocytochemical detection of Cx36 and Cx43 in adult LC showed that Cx36 was associated with neuronal processes while Cx43 was localized to glia. In adult LC, in vitro intracellular recordings combined with neurobiotin injections confirmed the presence of gap junctional communication albeit to a lesser extent than in early postnatal periods. The degree to which synaptic inputs to LC neurons impact on Cx protein expression was also evaluated. Samples of the LC from rats that received an electrolytic lesion of the amygdala were processed for western blot analysis of Cx36 and Cx43. The predominantly neuronal Cx36 exhibited an increase in expression while the glial Cx43 was unchanged. The present results indicate that, despite subtype-specific changes during development, several Cx proteins are expressed in the adult LC. In addition, manipulating afferent input to the LC, in adult rats, results in increases in neuronal Cx protein levels but not in glial Cx levels suggesting that altering synaptic inputs to the LC may alter synchronous activity in noradrenergic neurons.
Collapse
Affiliation(s)
- E J Van Bockstaele
- Department of Neurosurgery, Farber Institute of Neurosciences, Thomas Jefferson University, 1020 Locust Street, Suite 520, Philadelphia, PA 19107, USA.
| | | | | | | | | |
Collapse
|
50
|
Mills LR, Velumian AA, Agrawal SK, Theriault E, Fehlings MG. Confocal imaging of changes in glial calcium dynamics and homeostasis after mechanical injury in rat spinal cord white matter. Neuroimage 2004; 21:1069-82. [PMID: 15006675 DOI: 10.1016/j.neuroimage.2003.10.041] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 10/29/2003] [Accepted: 10/31/2003] [Indexed: 11/20/2022] Open
Abstract
Periaxonal glia play an important role in maintaining axonal function in white matter. However, little is known about the changes that occur in glial cells in situ immediately after traumatic injury. We used fluo-3 and confocal microscopy to examine the effects of localized (<0.5 mm) mechanical trauma on intracellular calcium (Ca(i)(2+)) levels in glial cells in a mature rat spinal cord white matter preparation in vitro. At the injury site, the glial Ca(i)(2+) signal increased by 300-400% within 5 min and then irreversibly declined indicating cell lysis and death. In glial cells at sites adjacent to the injury (1.5-2 mm from epicenter), Ca(i)(2+) levels peaked at 10-15 min, and thereafter declined but remained significantly above rest levels. At distal sites (6-9 mm), Ca(i)(2+) levels rose and declined even slower, peaking at 80-90 min. Injury in zero calcium dampened Ca(i)(2+) responses, indicating a role for calcium influx in the generation and propagation of the injury-induced Ca(i)(2+) signal. By 50-80 min post-injury, surviving glial cells demonstrated an enhanced ability to withstand supraphysiological Ca(i)(2+) loads induced by the calcium ionophore A-23187. Glial fibrillary acidic protein (GFAP) and CNPase immunolabeling determined that the glial cells imaged with fluo-3 included both astrocytes and oligodendrocytes. These data provide the first direct evidence that the effects of localized mechanical trauma include a glial calcium signal that can spread along white matter tracts for up to 9 mm within less than 3 h. The results further show that trauma can enhance calcium regulation in surviving glial cells in the acute post-injury period.
Collapse
Affiliation(s)
- Linda R Mills
- Division of Cellular and Molecular Biology, The Toronto Western Hospital Research Institute, University Health Network, Toronto, Canada.
| | | | | | | | | |
Collapse
|