1
|
Michinaga S, Hishinuma S, Koyama Y. Roles of Astrocytic Endothelin ET B Receptor in Traumatic Brain Injury. Cells 2023; 12:cells12050719. [PMID: 36899860 PMCID: PMC10000579 DOI: 10.3390/cells12050719] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 02/08/2023] [Accepted: 02/22/2023] [Indexed: 03/02/2023] Open
Abstract
Traumatic brain injury (TBI) is an intracranial injury caused by accidents, falls, or sports. The production of endothelins (ETs) is increased in the injured brain. ET receptors are classified into distinct types, including ETA receptor (ETA-R) and ETB receptor (ETB-R). ETB-R is highly expressed in reactive astrocytes and upregulated by TBI. Activation of astrocytic ETB-R promotes conversion to reactive astrocytes and the production of astrocyte-derived bioactive factors, including vascular permeability regulators and cytokines, which cause blood-brain barrier (BBB) disruption, brain edema, and neuroinflammation in the acute phase of TBI. ETB-R antagonists alleviate BBB disruption and brain edema in animal models of TBI. The activation of astrocytic ETB receptors also enhances the production of various neurotrophic factors. These astrocyte-derived neurotrophic factors promote the repair of the damaged nervous system in the recovery phase of patients with TBI. Thus, astrocytic ETB-R is expected to be a promising drug target for TBI in both the acute and recovery phases. This article reviews recent observations on the role of astrocytic ETB receptors in TBI.
Collapse
Affiliation(s)
- Shotaro Michinaga
- Department of Pharmacodynamics, Meiji Pharmaceutical University, 2-522-1 Noshio, Tokyo 204-8588, Japan
| | - Shigeru Hishinuma
- Department of Pharmacodynamics, Meiji Pharmaceutical University, 2-522-1 Noshio, Tokyo 204-8588, Japan
| | - Yutaka Koyama
- Laboratory of Pharmacology, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kita Higashinada, Kobe 668-8558, Japan
- Correspondence: ; Tel.: +81-78-441-7572
| |
Collapse
|
2
|
Koyama Y. Endothelin ET B Receptor-Mediated Astrocytic Activation: Pathological Roles in Brain Disorders. Int J Mol Sci 2021; 22:ijms22094333. [PMID: 33919338 PMCID: PMC8122402 DOI: 10.3390/ijms22094333] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/11/2022] Open
Abstract
In brain disorders, reactive astrocytes, which are characterized by hypertrophy of the cell body and proliferative properties, are commonly observed. As reactive astrocytes are involved in the pathogenesis of several brain disorders, the control of astrocytic function has been proposed as a therapeutic strategy, and target molecules to effectively control astrocytic functions have been investigated. The production of brain endothelin-1 (ET-1), which increases in brain disorders, is involved in the pathophysiological response of the nervous system. Endothelin B (ETB) receptors are highly expressed in reactive astrocytes and are upregulated by brain injury. Activation of astrocyte ETB receptors promotes the induction of reactive astrocytes. In addition, the production of various astrocyte-derived factors, including neurotrophic factors and vascular permeability regulators, is regulated by ETB receptors. In animal models of Alzheimer’s disease, brain ischemia, neuropathic pain, and traumatic brain injury, ETB-receptor-mediated regulation of astrocytic activation has been reported to improve brain disorders. Therefore, the astrocytic ETB receptor is expected to be a promising drug target to improve several brain disorders. This article reviews the roles of ETB receptors in astrocytic activation and discusses its possible applications in the treatment of brain disorders.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Kobe Pharmaceutical University, 4-19-1 Motoyama-Kita Higashinada, Kobe 668-8558, Japan
| |
Collapse
|
3
|
Koyama Y, Sumie S, Nakano Y, Nagao T, Tokumaru S, Michinaga S. Endothelin-1 stimulates expression of cyclin D1 and S-phase kinase-associated protein 2 by activating the transcription factor STAT3 in cultured rat astrocytes. J Biol Chem 2019; 294:3920-3933. [PMID: 30670587 DOI: 10.1074/jbc.ra118.005614] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 01/17/2019] [Indexed: 01/04/2023] Open
Abstract
Brain injury-mediated induction of reactive astrocytes often leads to glial scar formation in damaged brain regions. Activation of signal transducer and activator of transcription 3 (STAT3), a member of the STAT family of transcription factors, plays a pivotal role in inducing reactive astrocytes and glial scar formation. Endothelin-1 (ET-1) is a vasoconstrictor peptide, and its levels increase in brain disorders and promote astrocytic proliferation through ETB receptors. To clarify the mechanisms underlying ET-1-mediated astrocytic proliferation, here we examined its effects on STAT3 in cultured rat astrocytes. ET-1 treatment stimulated Ser-727 phosphorylation of STAT3 in the astrocytes, but Tyr-705 phosphorylation was unaffected, and ET-induced STAT3 Ser-727 phosphorylation was reduced by the ETB antagonist BQ788. ET-1 stimulated STAT3 binding to its consensus DNA-binding motifs. Monitoring G1/S phase cell cycle transition through bromodeoxyuridine (BrdU) incorporation, we found that ET-1 increases BrdU incorporation into the astrocytic nucleus, indicating cell cycle progression. Of note, STAT3 chemical inhibition (with stattic or 5,15-diphenyl-porphine (5,15-DPP)) or siRNA-mediated STAT3 silencing reduced ET-induced BrdU incorporation. Moreover, ET-1 increased astrocytic expression levels of cyclin D1 and S-phase kinase-associated protein 2 (SKP2), which were reduced by stattic, 5,15-DPP, and STAT3 siRNA. ChIP-based PCR analysis revealed that ET-1 promotes the binding of SAT3 to the 5'-flanking regions of rat cyclin D1 and SKP2 genes. Our results suggest that STAT3-mediated regulation of cyclin D1 and SKP2 expression underlies ET-induced astrocytic proliferation.
Collapse
Affiliation(s)
- Yutaka Koyama
- From the Laboratory of Pharmacology, Kobe Pharmaceutical University, 4-19-1 Motoyamakita, Higashinada, Kobe, 658-8558, Japan and
| | - Satoshi Sumie
- the Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| | - Yasutaka Nakano
- the Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| | - Tomoya Nagao
- the Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| | - Shiho Tokumaru
- the Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| | - Shotaro Michinaga
- the Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| |
Collapse
|
4
|
Abstract
Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.
Collapse
|
5
|
Koyama Y, Ukita A, Abe K, Iwamae K, Tokuyama S, Tanaka K, Kotake Y. Dexamethasone Downregulates Endothelin Receptors and Reduces Endothelin-Induced Production of Matrix Metalloproteinases in Cultured Rat Astrocytes. Mol Pharmacol 2017; 92:57-66. [PMID: 28461586 DOI: 10.1124/mol.116.107300] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 04/25/2017] [Indexed: 12/31/2022] Open
Abstract
In brain disorders, astrocytes change phenotype to reactive astrocytes and are involved in the induction of neuroinflammation and brain edema. The administration of glucocorticoids (GCs), such as dexamethasone (Dex), reduces astrocytic activation, but the mechanisms underlying this inhibitory action are not well understood. Endothelins (ETs) promote astrocytic activation. Therefore, the effects of Dex on ET receptor expressions were examined in cultured rat astrocytes. Treatment with 300 nM Dex for 6-48 hours reduced the mRNA expression of astrocytic ETA and ETB receptors to 30-40% of nontreated cells. Levels of ETA and ETB receptor proteins became about 50% of nontreated cells after Dex treatment. Astrocytic ETA and ETB receptor mRNAs were decreased by 300 nM hydrocortisone. The effects of Dex and hydrocortisone on astrocytic ET receptors were abolished in the presence of mifepristone, a GC receptor antagonist. Although Dex did not decrease the basal levels of matrix metalloproteinase (MMP) 3 and MMP9 mRNAs, pretreatment with Dex reduced ET-induced increases in MMP mRNAs. The effects of ET-1 on the release of MMP3 and MMP9 proteins were attenuated by pretreatment with Dex. ET-1 stimulated the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in cultured astrocytes. Pretreatment with Dex reduced the ET-induced increases in ERK1/2 phosphorylation. In contrast, pretreatment with Dex did not affect MMP production or ERK1/2 phosphorylation induced by phorbol myristate acetate, a protein kinase C activator. These results indicate that Dex downregulates astrocytic ET receptors and reduces ET-induced MMP production.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Ayano Ukita
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Kana Abe
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Kuniaki Iwamae
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Shogo Tokuyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Keisuke Tanaka
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| | - Yuki Kotake
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan (Y.Koy., A.U., K.A., K.I., K.T., Y.Kot.); and Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Kobe Gakuin University, Minatojima, Kobe, Japan (S.T.)
| |
Collapse
|
6
|
Xie D, Croaker GDH, Li J, Song ZM. Reduced cell proliferation and increased apoptosis in the hippocampal formation in a rat model of Hirschsprung's disease. Brain Res 2016; 1642:79-86. [PMID: 27017960 DOI: 10.1016/j.brainres.2016.03.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/26/2016] [Accepted: 03/15/2016] [Indexed: 12/22/2022]
Abstract
Hirschsprung's disease (HSCR) is a congenital malformation characterized by the absence of enteric ganglia in the distal intestine and gut obstruction. Some HSCR patients also have associated neurological symptoms. We studied a rat model of HSCR, also known as spotting lethal (sl/sl) rat, which carries a spontaneous deletion in the gene of endothelin receptor B (EDNRB) and a similar phenotype as humans with HSCR. We focused on the changes in cell proliferation and apoptosis in the hippocampal formation of the sl/sl rat. Proliferating cells in wildtype (+/+), heterozygous (+/sl) and homozygous (sl/sl) rats were labelled by intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) at postnatal day 2. The density of proliferating cells in the CA1 and CA3 regions of the hippocampus and dentate gyrus of sl/sl rats was significantly reduced compared to +/+ rats. The effect of EDNRB mutation on cell apoptosis was examined by using terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling assay. This showed that the density of apoptotic cells in the hippocampal formation, particularly in the CA1 region of sl/sl rats, was significantly increased compared to +/+ rats. The expression of brain derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) was measured with ELISA in the hippocampal formation, but no difference was revealed between genotypes. These results suggest that EDNRB mutation reduces cell proliferation and increases apoptosis in the hippocampal formation of the sl/sl rat, but does not alter the levels of BDNF and GDNF. Our findings provide an insight into the cellular changes in the brains of HSCR patients caused by EDNRB mutation.
Collapse
Affiliation(s)
- Dan Xie
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China; Eccles Institute of Neuroscience, John Curtin School of Medical Research, the Australian National University, Canberra, ACT, Australia
| | - G David H Croaker
- Department of Paediatric Surgery, The Canberra Hospital, Canberra, ACT, Australia
| | - Jimei Li
- Department of Neurology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China
| | - Zan-Min Song
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, the Australian National University, Canberra, ACT, Australia; Medical School, the Australian National University, Canberra, ACT, Australia.
| |
Collapse
|
7
|
Forner S, Martini A, de Andrade E, Rae G. Neuropathic pain induced by spinal cord injury: Role of endothelin ETA and ETB receptors. Neurosci Lett 2016; 617:14-21. [DOI: 10.1016/j.neulet.2016.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/21/2015] [Accepted: 02/02/2016] [Indexed: 01/25/2023]
|
8
|
Michinaga S, Seno N, Fuka M, Yamamoto Y, Minami S, Kimura A, Hatanaka S, Nagase M, Matsuyama E, Yamanaka D, Koyama Y. Improvement of cold injury-induced mouse brain edema by endothelin ETBantagonists is accompanied by decreases in matrixmetalloproteinase 9 and vascular endothelial growth factor-A. Eur J Neurosci 2015; 42:2356-70. [DOI: 10.1111/ejn.13020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 01/08/2023]
Affiliation(s)
- Shotaro Michinaga
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Naoki Seno
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Mayu Fuka
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Yui Yamamoto
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Shizuho Minami
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Akimasa Kimura
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Shunichi Hatanaka
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Marina Nagase
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Emi Matsuyama
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Daisuke Yamanaka
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| | - Yutaka Koyama
- Laboratory of Pharmacology; Faculty of Pharmacy; Osaka Ohtani University; 3-11-1 Nishikiori-Kita, Tonda-bayashi Osaka 584-8540 Japan
| |
Collapse
|
9
|
Koyama Y. Endothelin systems in the brain: involvement in pathophysiological responses of damaged nerve tissues. Biomol Concepts 2015; 4:335-47. [PMID: 25436584 DOI: 10.1515/bmc-2013-0004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 05/14/2013] [Indexed: 12/22/2022] Open
Abstract
In addition to their potent vasoconstriction effects, endothelins (ETs) show multiple actions in various tissues including the brain. The brain contains high levels of ETs, and their production is stimulated in many brain disorders. Accumulating evidence indicates that activation of brain ET receptors is involved in several pathophysiological responses in damaged brains. In this article, the roles of brain ET systems in relation to brain disorders are reviewed. In the acute phase of stroke, prolonged vasospasm of cerebral arteries and brain edema occur, both of which aggravate brain damage. Studies using ET antagonists show that activation of ETA receptors in the brain vascular smooth muscle induces vasospasm after stroke. Brain edema is induced by increased activity of vascular permeability factors, such as vascular endothelial growth factor and matrix metalloproteinases. Activation of ETB receptors stimulates astrocytic production of these permeability factors. Increases in reactive astrocytes are observed in neurodegenerative diseases and in the chronic phase of stroke, where they facilitate the repair of damaged nerve tissues by releasing neurotrophic factors. ETs promote the induction of reactive astrocytes through ETB receptors. ETs also stimulate the production of astrocytic neurotrophic factors. Recent studies have shown high expression of ETB receptors in neural progenitors. Activation of ETB receptors in neural progenitors promotes their proliferation and migration, suggesting roles for ETB receptors in neurogenesis. Much effort has been invested in the pursuit of novel drugs to induce protection or repair of damaged nerve tissues. From these studies, the pharmacological significance of brain ET systems as a possible target of neuroprotective drugs is anticipated.
Collapse
|
10
|
Pathogenesis of brain edema and investigation into anti-edema drugs. Int J Mol Sci 2015; 16:9949-75. [PMID: 25941935 PMCID: PMC4463627 DOI: 10.3390/ijms16059949] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/15/2015] [Accepted: 04/27/2015] [Indexed: 12/18/2022] Open
Abstract
Brain edema is a potentially fatal pathological state that occurs after brain injuries such as stroke and head trauma. In the edematous brain, excess accumulation of extracellular fluid results in elevation of intracranial pressure, leading to impaired nerve function. Despite the seriousness of brain edema, only symptomatic treatments to remove edema fluid are currently available. Thus, the development of novel anti-edema drugs is required. The pathogenesis of brain edema is classified as vasogenic or cytotoxic edema. Vasogenic edema is defined as extracellular accumulation of fluid resulting from disruption of the blood-brain barrier (BBB) and extravasations of serum proteins, while cytotoxic edema is characterized by cell swelling caused by intracellular accumulation of fluid. Various experimental animal models are often used to investigate mechanisms underlying brain edema. Many soluble factors and functional molecules have been confirmed to induce BBB disruption or cell swelling and drugs targeted to these factors are expected to have anti-edema effects. In this review, we discuss the mechanisms and involvement of factors that induce brain edema formation, and the possibility of anti-edema drugs targeting them.
Collapse
|
11
|
Signaling molecules regulating phenotypic conversions of astrocytes and glial scar formation in damaged nerve tissues. Neurochem Int 2014; 78:35-42. [DOI: 10.1016/j.neuint.2014.08.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/17/2014] [Accepted: 08/22/2014] [Indexed: 12/21/2022]
|
12
|
Koyama Y, Michinaga S. [Roles of astroglia in the regulations of brain vascular permeability]. Nihon Yakurigaku Zasshi 2014; 144:115-119. [PMID: 25213611 DOI: 10.1254/fpj.144.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
|
13
|
Koyama Y, Hayashi M, Nagae R, Tokuyama S, Konishi T. Endothelin-1 increases the expression of VEGF-R1/Flt-1 receptors in rat cultured astrocytes through ETB receptors. J Neurochem 2014; 130:759-69. [PMID: 24862165 DOI: 10.1111/jnc.12770] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 05/22/2014] [Accepted: 05/23/2014] [Indexed: 01/04/2023]
Abstract
Expressions of vascular endothelial growth factor (VEGF) receptors in astrocytes are increased in damaged brains. To clarify the regulatory mechanisms of VEGF receptors, the effects of endothelin-1 (ET-1) were examined in rat cultured astrocytes. Expressions of VEGF-R1 and -R2 receptor mRNA were at similar levels, whereas the mRNA expressions of VEGF-R3 and Tie-2, a receptor for angiopoietins, were lower. Placenta growth factor, a selective agonist of the VEGF-R1 receptor, induced phosphorylation of focal adhesion kinase (FAK) and extracellular signal regulated kinase 1/2 (ERK1/2). Phosphorylations of FAK and ERK 1/2 were also stimulated by VEGF-E, a selective VEGF-R2 agonist. Increased phosphorylations of FAK and ERK1/2 by VEGF165 were reduced by selective antagonists for VEGF-R1 and -R2. Treatment with ET-1 increased VEGF-R1 mRNA and protein levels. The effects of ET-1 on VEGF-R1 mRNA were mimicked by Ala(1,3,11,15) -ET-1, a selective agonist for ETB receptors, and inhibited by BQ788, an ETB antagonist. ET-1 did not affect the mRNA levels of VEGF-R2, -R3, and Tie-2. Pre-treatment with ET-1 potentiated the effects of placenta growth factor on phosphorylations of FAK and ERK1/2. These findings suggest that ET-1 induces up-regulation of VEGF-R1 receptors in astrocytes, and potentiates VEGF signals in damaged nerve tissues. To clarify the regulatory mechanisms of vascular endothelial growth factor (VEGF) receptors, the effects of endothelin-1 (ET-1) were examined in rat cultured astrocytes. Effects of selective VEGF-R1 and R2 agonist showed that these receptors were linked to focal adhesion kinase (FAK) and extracellular signal regulated kinase 1/2 (ERK1/2). Treatment with ET-1 increased expression of VEGF-R1, which was mediated by ETB receptors. Pre-treatment with ET-1 potentiated the VEGF-R1-mediated activations of FAK and ERK1/2. These findings suggest that ET-1 induces up-regulation of VEGF-R1 receptors in astrocytes.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Osaka, Japan
| | | | | | | | | |
Collapse
|
14
|
Michinaga S, Nagase M, Matsuyama E, Yamanaka D, Seno N, Fuka M, Yamamoto Y, Koyama Y. Amelioration of cold injury-induced cortical brain edema formation by selective endothelin ETB receptor antagonists in mice. PLoS One 2014; 9:e102009. [PMID: 25000290 PMCID: PMC4084986 DOI: 10.1371/journal.pone.0102009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/13/2014] [Indexed: 12/13/2022] Open
Abstract
Brain edema is a potentially fatal pathological condition that often occurs in stroke and head trauma. Following brain insults, endothelins (ETs) are increased and promote several pathophysiological responses. This study examined the effects of ETB antagonists on brain edema formation and disruption of the blood-brain barrier in a mouse cold injury model (Five- to six-week-old male ddY mice). Cold injury increased the water content of the injured cerebrum, and promoted extravasation of both Evans blue and endogenous albumin. In the injury area, expression of prepro-ET-1 mRNA and ET-1 peptide increased. Intracerebroventricular (ICV) administration of BQ788 (ETB antagonist), IRL-2500 (ETB antagonist), or FR139317 (ETA antagonist) prior to cold injury significantly attenuated the increase in brain water content. Bolus administration of BQ788, IRL-2500, or FR139317 also inhibited the cold injury-induced extravasation of Evans blue and albumin. Repeated administration of BQ788 and IRL-2500 beginning at 24 h after cold injury attenuated both the increase in brain water content and extravasation of markers. In contrast, FR139317 had no effect on edema formation when administrated after cold injury. Cold injury stimulated induction of glial fibrillary acidic protein-positive reactive astrocytes in the injured cerebrum. Induction of reactive astrocytes after cold injury was attenuated by ICV administration of BQ788 or IRL-2500. These results suggest that ETB receptor antagonists may be an effective approach to ameliorate brain edema formation following brain insults.
Collapse
Affiliation(s)
- Shotaro Michinaga
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Marina Nagase
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Emi Matsuyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Daisuke Yamanaka
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Naoki Seno
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Mayu Fuka
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Yui Yamamoto
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
| | - Yutaka Koyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka, Japan
- * E-mail:
| |
Collapse
|
15
|
Michinaga S, Ishida A, Takeuchi R, Koyama Y. Endothelin-1 stimulates cyclin D1 expression in rat cultured astrocytes via activation of Sp1. Neurochem Int 2013; 63:25-34. [PMID: 23619396 DOI: 10.1016/j.neuint.2013.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/25/2013] [Accepted: 04/08/2013] [Indexed: 11/16/2022]
Abstract
Endothelins (ETs), a family of vasoconstrictor peptides, are up-regulated in several pathological conditions in the brain, and induce astrocytic proliferation. We previously observed that ET-1 increased the expression of cyclin D1 protein. Thus, we confirmed the intracellular up-regulation of cyclin D1 by ET-1 in rat cultured astrocytes. Real-time PCR analysis indicated that ET-1 (100 nM) and Ala(1,3,11,15)-ET-1 (100 nM), a selective agonist of the ETB receptor, induced a time-dependent and transient increase in cyclin D1 mRNA. The effect of ET-1 was diminished by an ETB antagonist (1 μM BQ788) or inhibitors of Sp1 (500 nM mithramycin), ERK (50 μM PD98059), p38 (20 μM SB203580) and JNK (1 μM SP600125), but not inhibitors of NF-κB (10 μM SN50 and 100 μM pyrrolidine dithiocarbamate). The binding assay for Sp1 indicated that ET-1 increased the binding activity of Sp1 to consensus sequences, and two oligonucleotides of the cyclin D1 promoter including the Sp1-binding sites diminished the effect of ET-1. Western blot analysis showed that ET-1 induced time-dependent and transient phosphorylation of Sp1 on Thr453 and Thr739 via the ETB receptor. ET-1-induced phosphorylation of Sp1 was attenuated by PD98059 and SP600125. Additionally, ET-1 increased the incorporation of bromodeoxyuridine (BrdU) in cultured astrocytes and the number of BrdU-positive cells decreased in the presence of PD98059, SP600125 and mithramycin. These results suggest that ET-1 increases the expression of cyclin D1 via activation of Sp1 and induces astrocytic proliferation.
Collapse
Affiliation(s)
- Shotaro Michinaga
- Faculty of Pharmacy, Laboratory of Pharmacology, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tonda-bayashi, Osaka 584-8540, Japan
| | | | | | | |
Collapse
|
16
|
Filosa JA, Naskar K, Perfume G, Iddings JA, Biancardi VC, Vatta MS, Stern JE. Endothelin-mediated calcium responses in supraoptic nucleus astrocytes influence magnocellular neurosecretory firing activity. J Neuroendocrinol 2012; 24:378-92. [PMID: 22007724 DOI: 10.1111/j.1365-2826.2011.02243.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In addition to their peripheral vasoactive effects, accumulating evidence supports an important role for endothelins (ETs) in the regulation of the hypothalamic magnocellular neurosecretory system, which produces and releases the neurohormones vasopressin (VP) and oxytocin (OT). Still, the precise cellular substrates, loci and mechanisms underlying the actions of ETs on the magnocellular system are poorly understood. In the present study, we combined patch-clamp electrophysiology, confocal Ca(2+) imaging and immunohistochemistry to study the actions of ETs on supraoptic nucleus (SON) magnocellular neurosecretory neurones and astrocytes. Our studies show that ET-1 evoked rises in [Ca(2+) ](i) levels in SON astrocytes (but not neurones), an effect largely mediated by the activation of ET(B) receptors and mobilisation of thapsigargin-sensitive Ca(2+) stores. The presence of ET(B) receptors in SON astrocytes was also verified immunohistochemically. ET(B) receptor activation either increased (75%) or decreased (25%) SON firing activity, both in VP and putative OT neurones, and these effects were prevented when slices were preincubated in glutamate receptor blockers or nitric oxide synthase blockers, respectively. Moreover, ET(B) -mediated effects in SON neurones were also prevented by a gliotoxin compound, and when changes in [Ca(2+) ](i) were prevented with bath-applied BAPTA-AM or thapsigargin. Conversely, intracellular Ca(2+) chelation in the recorded SON neurones failed to block ET(B) -mediated effects. In summary, our results indicate that ET(B) receptor activation in SON astrocytes induces the mobilisation of [Ca(2+) ](i) , likely resulting in the activation of glutamate and nitric oxide signalling pathways, evoking in turn excitatory and inhibitory SON neuronal responses, respectively. Taken together, our study supports an important role for astrocytes in mediating the actions of ETs on the magnocellular neurosecretory system.
Collapse
Affiliation(s)
- J A Filosa
- Department of Physiology, Georgia Health Sciences University, Augusta, GA 30912, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Koyama Y, Michinaga S. Regulations of Astrocytic Functions by Endothelins: Roles in the Pathophysiological Responses of Damaged Brains. J Pharmacol Sci 2012; 118:401-7. [DOI: 10.1254/jphs.11r13cp] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
|
18
|
I.c.v administration of an endothelin ETB receptor agonist stimulates vascular endothelial growth factor-A production and activates vascular endothelial growth factor receptors in rat brain. Neuroscience 2011; 192:689-98. [DOI: 10.1016/j.neuroscience.2011.05.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/25/2011] [Accepted: 05/25/2011] [Indexed: 11/17/2022]
|
19
|
Prasanna G, Krishnamoorthy R, Yorio T. Endothelin, astrocytes and glaucoma. Exp Eye Res 2011; 93:170-7. [PMID: 20849847 PMCID: PMC3046320 DOI: 10.1016/j.exer.2010.09.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 09/02/2010] [Accepted: 09/07/2010] [Indexed: 12/25/2022]
Abstract
It has become increasingly clear that astrocytes may play an important role in the genesis of glaucoma. Astrogliosis occurs in response to ocular stress or the presence of noxious stimuli. Agents that appear to stimulate reactive gliosis are becoming increasingly clear. One class of agents that is emerging is the endothelins (ETs; specifically, ET-1). In this review we examine the interactions of ET-1 with astrocytes and provide examples where ET-1 appears to contribute to activation of astrocytes and play a role in the neurodegenerative effects that accompany such reactivation resulting in astrogliosis. These actions are presented in the context of glaucoma although information is also presented with respect to ET-1's role in the central nervous system and brain. While much has been learned with respect to ET-1/astrocyte interactions, there are still a number of questions concerning the potential therapeutic implications of these findings. Hopefully this review will stimulate others to examine this potential.
Collapse
Affiliation(s)
- Ganesh Prasanna
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
| | | | | |
Collapse
|
20
|
Tanaka K, Koyama Y. Endothelins decrease the expression of aquaporins and plasma membrane water permeability in cultured rat astrocytes. J Neurosci Res 2010; 89:320-8. [DOI: 10.1002/jnr.22559] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 10/20/2010] [Accepted: 10/25/2010] [Indexed: 11/09/2022]
|
21
|
Koyama Y, Tanaka K. Intracerebroventricular administration of an endothelin ET(B)-receptor agonist increases expression of matrix metalloproteinase-2 and -9 in rat brain. J Pharmacol Sci 2010; 114:433-43. [PMID: 21127388 DOI: 10.1254/jphs.10195fp] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Matrix metalloproteinases (MMPs), a family of zinc-endopeptidases, have a critical role in the pathophysiological responses in damaged brains. MMPs are up-regulated in brain pathologies. To clarify the extracellular signals involved in brain MMP production, the effects of endothelins (ETs), a family of vasoconstricting peptides, were examined. Intracerebroventricular administration of 500 pmol/day Ala(1,3,11,15)-ET-1, an ET(B)-receptor agonist, increased the mRNAs of MMP2 and MMP9 in rat hippocampus and cerebrum. Ala(1,3,11,15)-ET-1 did not affect mRNA levels of MMP 1, 12, and 14. Administration of Ala(1,3,11,15)-ET-1 for 7 days also increased the protein content and proteolytic activities of MMP2 and MMP9 in the cerebrum. Immunohistochemical observations showed that astrocytes in the hippocampus and the cerebrum of ET-infused rats had MMP2 and MMP9 reactivities. In rat cultured astrocytes, both Ala(1,3,11,15)-ET-1 (100 nM) and ET-1 (100 nM) increased MMP2 and MMP9 mRNAs. ET-1 stimulated the protein releases and the proteolytic activities of MMP2 and MMP9 from cultured astrocytes. BQ788, an ET(B) antagonist, inhibited the effects of ET-1 on astrocytic MMP2 and MMP9. The ET-induced expression of MMP9, but not MMP2, was inhibited by pyrrolidine dithiocarbamate, proteasome inhibitor I, and MG132. These results suggest that ET stimulates astrocytic MMP2 and MMP9 production through ET(B) receptors.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Faculty of Pharmacy, Osaka Ohtani University, Tonda-bayashi, Osaka 584-8540, Japan.
| | | |
Collapse
|
22
|
Ståhlberg A, Andersson D, Aurelius J, Faiz M, Pekna M, Kubista M, Pekny M. Defining cell populations with single-cell gene expression profiling: correlations and identification of astrocyte subpopulations. Nucleic Acids Res 2010; 39:e24. [PMID: 21112872 PMCID: PMC3045576 DOI: 10.1093/nar/gkq1182] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Single-cell gene expression levels show substantial variations among cells in seemingly homogenous populations. Astrocytes perform many control and regulatory functions in the central nervous system. In contrast to neurons, we have limited knowledge about functional diversity of astrocytes and its molecular basis. To study astrocyte heterogeneity and stem/progenitor cell properties of astrocytes, we used single-cell gene expression profiling in primary mouse astrocytes and dissociated mouse neurosphere cells. The transcript number variability for astrocytes showed lognormal features and revealed that cells in primary cultures to a large extent co-express markers of astrocytes and neural stem/progenitor cells. We show how subpopulations of cells can be identified at single-cell level using unsupervised algorithms and that gene correlations can be used to identify differences in activity of important transcriptional pathways. We identified two subpopulations of astrocytes with distinct gene expression profiles. One had an expression profile very similar to that of neurosphere cells, whereas the other showed characteristics of activated astrocytes in vivo.
Collapse
Affiliation(s)
- Anders Ståhlberg
- Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy at University of Gothenburg, Medicinaregatan 9A, 413 90 Gothenburg, Sweden.
| | | | | | | | | | | | | |
Collapse
|
23
|
Li J, Wu L, Cao Q, Yuan Y, Yang L, Guo Z, Kaur C, Sivakumar V, Ling E, Wu C. Endothelins-1/3 and endothelin-A/B receptors expressing glial cells with special reference to activated microglia in experimentally induced cerebral ischemia in the adult rats. Neuroscience 2010; 167:665-77. [DOI: 10.1016/j.neuroscience.2010.02.062] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 02/11/2010] [Accepted: 02/23/2010] [Indexed: 01/23/2023]
|
24
|
Castañeda MM, Cubilla MA, López-Vicchi MM, Suburo AM. Endothelinergic cells in the subependymal region of mice. Brain Res 2010; 1321:20-30. [DOI: 10.1016/j.brainres.2010.01.056] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 01/14/2010] [Accepted: 01/20/2010] [Indexed: 10/19/2022]
|
25
|
Rachid MA, Teixeira AL, Barcelos LS, Machado CRS, Chiari E, Tanowitz HB, Camargos ERS, Teixeira MM. Role of endothelin receptors in the control of central nervous system parasitism in Trypanosoma cruzi infection in rats. J Neuroimmunol 2010; 220:64-8. [PMID: 20116865 DOI: 10.1016/j.jneuroim.2010.01.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 12/02/2009] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
Abstract
Endothelin has been implicated in the pathogenesis of experimental and human Chagas disease. In the present study, we investigated whether the treatment with bosentan, an antagonist of both ET(A)/ET(B) endothelin receptors, modified parasite load and inflammation in the central nervous system (CNS) of Trypanosomacruzi-infected rats. The cerebellum was the most affected region in the CNS with marked parasitism and inflammation. Treatment with bosentan enhanced parasitemia and CNS parasitism, but control of infection was eventually attained. There was also an increase in the levels of the cytokines TNF-alpha, IL-10, IFN-gamma, CCL2/MCP-1, CCL3/MIP-1alpha and CCL5/RANTES in the brain of infected animals at days 9, 13 and 18 after infection. Overall, bosentan has some effects on the expression of certain cytokines and this may be related to the initial enhanced parasite load. Altogether, our data suggest that endothelin action via ET(A) and ET(B) receptors may play a role in the initial resistance of the CNS to T. cruzi infection in rats.
Collapse
Affiliation(s)
- Milene A Rachid
- Departamento de Patologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31270901, Belo Horizonte, MG, Brazil.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Endothelin-1 reverses the histone deacetylase inhibitor-induced increase in glial glutamate transporter transcription without affecting histone acetylation levels. Neurochem Int 2009; 55:22-7. [DOI: 10.1016/j.neuint.2008.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 12/19/2008] [Accepted: 12/22/2008] [Indexed: 12/21/2022]
|
27
|
Vidovic M, Chen MM, Lu QY, Kalloniatis KF, Martin BM, Tan AHY, Lynch C, Croaker GDH, Cass DT, Song ZM. Deficiency in endothelin receptor B reduces proliferation of neuronal progenitors and increases apoptosis in postnatal rat cerebellum. Cell Mol Neurobiol 2008; 28:1129-38. [PMID: 18683040 DOI: 10.1007/s10571-008-9292-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 06/17/2008] [Indexed: 12/19/2022]
Abstract
Endothelins regulate cellular functions in the mammalian brain through the endothelin receptors A and B (EDNRA and EDNRB). In this study, we investigated the role of EDNRB on cell proliferation in the cerebellum by using the spotting lethal (sl) rat, which carries a naturally occurring deletion in the EDNRB gene. Proliferating cells in the three genotypes, wild-type (+/+), heterozygous (+/sl) and homozygous mutant (sl/sl) rats were labelled by intraperitoneal injection of 5-bromo-2'-deoxyuridine (BrdU) at postnatal day 2. The density of BrdU-positive cells (per mm(2)) in the external germinal layer of sl/sl rats (Mean +/- SEM, 977 +/- 388) was significantly reduced compared to +/+ (4915 +/- 631) and +/sl (2304 +/- 557) rats. Subsequently, we examined the effects of EDNRB mutation on neural apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP nick end-labelling assay. This showed that the density of apoptotic cells in the cerebella of sl/sl rats (9.3 +/- 0.5/mm(2)) was significantly more increased than +/+ rats (4 +/- 0.7). The expression of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) were measured with standard ELISA, but were unchanged in all genotypes. These results suggest that ENDRB mediates neural proliferation and have anti-apoptotic effects in the cerebellum of the postnatal rat, and that these effects are independent of changes in the expression of BDNF and GDNF. Our findings will lead to better understanding of the morphological changes in the cerebellum of Hirschsprung's disease patients with congenital EDNRB mutation.
Collapse
Affiliation(s)
- Maria Vidovic
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Koyama Y, Baba A, Matsuda T. Production of monocyte chemoattractant protein-1 and cytokine-induced neutrophil chemoattractant-1 in rat brain is stimulated by intracerebroventricular administration of an endothelin ETB receptor agonist. Neuroreport 2007; 18:1275-9. [PMID: 17632282 DOI: 10.1097/wnr.0b013e32825a67f1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The role of endothelin (ET)B receptors in chemokine production in the brain of rats was examined. Intracerebroventricular administration of 500 pmol/day of Ala(1,3,11,15)-ET-1, a selective ETB agonist, for 3 or 7 days increased monocyte chemoattractant protein (MCP)-1 and cytokine-induced neutrophil chemoattractant (CINC)-1 mRNA in the caudate-putamen and cerebrum, whereas it had no effects on regulated on activation normal T-cell expressed and secreted (RANTES), fractalkine and stromal cell-derived factor (SDF)-1alpha mRNA expression. Immunoreactive MCP-1 and CINC-1 in the caudate-putamen and the cerebrum were increased by the ETB agonist. Immunohistochemical observations on the Ala(1,3,11,15)-ET-1-infused rats showed that glial fibrillary acidic protein-positive astrocytes had immunoreactivity for MCP-1 and CINC-1. These findings indicate that the activation of brain ETB receptors causes the production of MCP-1 and CINC-1, and suggest a pathophysiological role for brain ETB receptors in nervous system damage.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Pharmacology, Osaka Ohtani University, Tonda-bayashi Laboratories, Osaka, Japan.
| | | | | |
Collapse
|
29
|
Stokely ME, Bhat MA, Koulen P. Microfluorimetry defines early axonal damage in a rat model of optic neuritis: a novel method targeting early CNS autoimmunity. J Neurosci Methods 2007; 166:217-28. [PMID: 17719649 DOI: 10.1016/j.jneumeth.2007.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/29/2007] [Accepted: 07/13/2007] [Indexed: 01/28/2023]
Abstract
Autoimmune optic neuritis is a common early manifestation of multiple sclerosis (MS), yet early therapeutic interventions for MS often have high ocular toxicity associated with increased risks for glaucoma, cataract, or retinopathy. This need to discover better early treatment options prompted our development of a sensitive and reliable means to quantify the broad range of pathologies that potentially develop very early in autoimmune optic neuritis. Tissue microfluorimetry was used to measure seven established markers for human MS pathology in normal and autoimmune optic nerves 13 days after antigen exposure, in a Brown Norway rat model of myelin oligodendrocyte glycoprotein (MOG) peptide (35-55)-induced autoimmune optic neuritis. Optic neuritis rats demonstrated early and significant pathologic changes in five established indices for neuroinflammation, immune infiltration, and demyelination that accurately modeled pathologies characteristic of MS. Two indices of MS-like axon damage advanced significantly within 13 days of antigen exposure. Fluorimetrically measured immunoreactivity (-ir) was significantly decreased for paranodin (PN, the requisite axonal paranodal junction protein) and significantly increased for amyloid precursor protein (APP), indicating loss of paranodal junctions and impaired fast axonal transport, respectively. Measurements showing decreased PN-ir with increased APP-ir quantitatively defined a pattern of early axonal damage in autoimmune optic neuritis.
Collapse
Affiliation(s)
- Martha E Stokely
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107, USA
| | | | | |
Collapse
|
30
|
Pekny M, Wilhelmsson U, Bogestål YR, Pekna M. The role of astrocytes and complement system in neural plasticity. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:95-111. [PMID: 17678957 DOI: 10.1016/s0074-7742(07)82005-8] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In neurotrauma, brain ischemia or neurodegenerative diseases, astrocytes become reactive (which is known as reactive gliosis) and this is accompanied by an altered expression of many genes. Two cellular hallmarks of reactive gliosis are hypertrophy of astrocyte processes and the upregulation of the part of the cytoskeleton known as intermediate filaments, which are composed of nestin, vimentin, and GFAP. Our aim has been to better understand the function of reactive astrocytes in CNS diseases. Using mice deficient for astrocyte intermediate filaments (GFAP(-/-)Vim(-/-)), we were able to attenuate reactive gliosis and slow down the healing process after neurotrauma. We demonstrated the key role of reactive astrocytes in neurotrauma-at an early stage after neurotrauma, reactive astrocytes have a neuroprotective effect; at a later stage, they facilitate the formation of posttraumatic glial scars and inhibit CNS regeneration, specifically, they seem to compromise neural graft survival and integration, reduce the extent of synaptic regeneration, inhibit neurogenesis in the old age, and inhibit regeneration of severed CNS axons. We propose that reactive astrocytes are the future target for the therapeutic strategies promoting regeneration and plasticity in the brain and spinal cord in various disease conditions. Through its involvement in inflammation, opsonization, and cytolysis, complement protects against infectious agents. Although most of the complement proteins are synthesized in CNS, the role of the complement system in the normal or ischemic CNS remains unclear. Complement activiation in the CNS has been generally considered as contributing to tissue damage. However, growing body of evidence suggests that complement may be a physiological neuroprotective mechanism as well as it may participate in maintenance and repair of the adult brain.
Collapse
Affiliation(s)
- Milos Pekny
- Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute for Neuroscience and Physiology at Sahlgrenska Academy Göteborg University, 405 30 Göteborg, Sweden
| | | | | | | |
Collapse
|
31
|
Hagemann TL, Connor JX, Messing A. Alexander disease-associated glial fibrillary acidic protein mutations in mice induce Rosenthal fiber formation and a white matter stress response. J Neurosci 2006; 26:11162-73. [PMID: 17065456 PMCID: PMC6674663 DOI: 10.1523/jneurosci.3260-06.2006] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mutations in the gene for the astrocyte specific intermediate filament, glial fibrillary acidic protein (GFAP), cause the rare leukodystrophy Alexander disease (AxD). To study the pathology of this primary astrocyte defect, we have generated knock-in mice with missense mutations homologous to those found in humans. In this report, we show that mice with GFAP-R76H and -R236H mutations develop Rosenthal fibers, the hallmark protein aggregates observed in astrocytes in AxD, in the hippocampus, corpus callosum, olfactory bulbs, subpial, and periventricular regions. Astrocytes in these areas appear reactive and total GFAP expression is elevated. Although general white matter architecture and myelination appear normal, when crossed with an antioxidant response element reporter line, the mutant mice show a distinct pattern of reporter-gene induction that is especially prominent in the corpus callosum, and histochemical staining reveals accumulation of iron in the same region. The mutant mice have a normal lifespan and show no overt behavioral defects, but are more susceptible to kainate-induced seizures. Although these mice demonstrate increased GFAP expression by themselves, further elevation of GFAP via crosses to GFAP transgenic animals leads to a shift in GFAP solubility, an increased stress response, and ultimately death. The mice do not display the full spectrum of pathology observed in human infantile AxD, but may more closely resemble the adult form of the disease. These studies provide formal proof linking GFAP mutations with Rosenthal fibers and oxidative stress, and correlate gliosis and GFAP protein levels to the severity of the disease.
Collapse
Affiliation(s)
- Tracy L Hagemann
- Waisman Center, University of Wisconsin, Madison, Wisconsin 53705, USA.
| | | | | |
Collapse
|
32
|
Rattner A, Nathans J. The genomic response to retinal disease and injury: evidence for endothelin signaling from photoreceptors to glia. J Neurosci 2006; 25:4540-9. [PMID: 15872101 PMCID: PMC6725023 DOI: 10.1523/jneurosci.0492-05.2005] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Regardless of proximal cause, photoreceptor injury or disease almost invariably leads to the activation of Muller cells, the principal glial cells in the retina. This observation implies the existence of signaling systems that inform Muller cells of the health status of photoreceptors. It further suggests that diverse types of photoreceptor damage elicit a limited range of biochemical responses. Using the mouse retina, we show by microarray, RNA blot, and in situ hybridization that the genomic responses to both light damage and inherited photoreceptor degeneration involve a relatively small number of genes and that the genes activated by these two insults overlap substantially with one another and with the genes activated by retinal detachment. Among the induced transcripts, those coding for endothelin2 (Edn2) are unusual in that they are localized to photoreceptors and are also highly induced in all of the tested models of photoreceptor disease or injury. Acute light damage also leads to a >10-fold increase in endothelin receptor B (Ednrb) in Muller cells 24 h after injury. These observations suggest that photoreceptor-derived EDN2 functions as a general stress signal, that EDN2 signals to Muller cells by binding to EDNRB, and that Muller cells can increase their sensitivity to EDN2 as part of the injury response.
Collapse
Affiliation(s)
- Amir Rattner
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
| | | |
Collapse
|
33
|
Syed H, Safa R, Chidlow G, Osborne NN. Sulfisoxazole, an endothelin receptor antagonist, protects retinal neurones from insults of ischemia/reperfusion or lipopolysaccharide. Neurochem Int 2006; 48:708-17. [PMID: 16464516 DOI: 10.1016/j.neuint.2005.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 12/07/2005] [Accepted: 12/19/2005] [Indexed: 12/29/2022]
Abstract
Endothelins exert pathological effects in the eye and much interest centres on their role in causing retinal neuronal death in ischemic diseases like glaucoma. In the present study the influence of the non-selective endothelin antagonist, sulfisoxazole on raised intraocular pressure-induced ischemia to the rat retina was investigated. Moreover, in vitro studies on primary rat retinal cultures were undertaken to see whether sulfisoxazole is able to blunt the toxic effect of lipopolysaccharide (LPS) to retinal neurones. In order to determine whether sulfisoxazole provides protection to the retina the a- and b-wave amplitudes of the electroretinogram (ERG), the localisation of retinal choline acetyltransferase (ChAT), nitric oxide synthase (nNOS) and Thy-1 and the retinal mRNA levels of Thy-1 and FGF-2 were deduced in retinas subjected to ischemia in the absence or presence of sulfisoxazole. The results showed that the ischemia-induced changes to the a- and b-wave amplitudes of the ERG and changes associated with the localisation of ChAT, nNOS and Thy-1 to be significantly blunted by sulfisoxazole. However, while the ischemia-induced changes to Thy-1 and FGF-2 mRNAs were reduced by sulfisoxazole, the reduction was non-significant. The in vitro studies provided support for the protective effect of sulfisoxazole. Here, it was clearly shown that sulfisoxazole attenuated the elevation of nitric oxide (deduced by measuring nitrite) and the reduction in numbers of GABA-containing neurones caused by LPS. The present study provides evidence for the first time that endothelin antagonist can protect the retina from ischemic-like insults as occurs in glaucoma.
Collapse
Affiliation(s)
- Husnain Syed
- Nuffield Laboratory of Ophthalmology, Oxford University, Walton Street, Oxford OX2 6AW, UK
| | | | | | | |
Collapse
|
34
|
Koyama Y, Baba A, Matsuda T. Endothelins stimulate the expression of neurotrophin-3 in rat brain and rat cultured astrocytes. Neuroscience 2005; 136:425-33. [PMID: 16181740 DOI: 10.1016/j.neuroscience.2005.08.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 07/31/2005] [Accepted: 08/01/2005] [Indexed: 10/25/2022]
Abstract
Endothelins play a role in the regulation of astrocytic functions in brain pathologies such as hyperplasia and neurotrophic factor production. The present study examined the effects of endothelins on production of neurotrophin-3, a member of the neurotrophin family of neurotrophic factors, in cultured astrocytes and rat brain. Quantitative reverse transcription-PCR analysis of mRNA copy numbers showed that cultured astrocytes expressed comparable numbers of neurotrophin-3 and neurotrophin-4/5 mRNA copies to nerve growth factor and brain-derived neurotrophic factor. Endothelin-1 (100 nM) and Ala1,3,11,15-endothelin-1 (an endothelinB receptor agonist, 100 nM) caused a transient increase in neurotrophin-3 mRNA levels, but not in neurotrophin-4/5 levels, in cultured astrocytes. The increases in mRNA levels were accompanied with that in extracellular release of neurotrophin-3. The effects of endothelin-1 on neurotrophin-3 mRNA levels were reduced by BQ788, an endothelinB receptor antagonist. I.c.v. administration of 500 pmol/day Ala1,3,11,15-endothelin-1 increased mRNA and peptide levels of neurotrophin-3 in rat caudate putamen and cerebrum. On the other hand, neurotrophin-3 production in hippocampus was not affected by Ala1,3,11,15-endothelin-1. Immunohistochemical examination of Ala1,3,11,15-endothelin-1-infused rats showed that neurotrophin-3 was mainly expressed in glial fibrillary acidic protein-positive astrocytes in caudate putamen and cerebrum. endothelin-induced increases in neurotrophin-3 expression in cultured astrocytes were inhibited by chelation of intracellular Ca2+ and PD98095 (an ERK inhibitor). These results suggest that endothelin is an extracellular signal that stimulates astrocytic neurotrophin-3 production in brain pathologies.
Collapse
Affiliation(s)
- Y Koyama
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-Oka 1-6 Suita, 565-0871, Japan
| | | | | |
Collapse
|
35
|
Koyama Y, Tsujikawa K, Matsuda T, Baba A. Endothelin increases expression of exon III- and exon IV-containing brain-derived neurotrophic factor transcripts in cultured astrocytes and rat brain. J Neurosci Res 2005; 80:809-16. [PMID: 15898104 DOI: 10.1002/jnr.20512] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effects of endothelins (ETs) on brain-derived neurotrophic factor (BDNF) production in astrocytes were investigated. ET-1 (100 nM) increased the mRNA level and extracellular release of BDNF in cultured astrocytes. RT-PCR analyses using primer pairs that amplified exon-specific BDNF transcripts revealed that exon III- and exon IV-containing BDNF transcripts existed in cultured astrocytes, whereas exon I- and exon II-containing BDNF transcripts did not. ET-1 and Ala(1,3,11,15)-ET-1, an ET(B) receptor agonist, increased the expressions of the exon III and exon IV transcripts in cultured astrocytes. Intracerebroventricular administration of 500 pmol/day of Ala(1,3,11,15)-ET-1 increased exon III and exon IV BDNF transcripts in the rat striatum. In cultured astrocytes, Ca(2+)-chelation, W-7 (a calmodulin inhibitor), and KN93 (a Ca(2+)/calmodulin kinase inhibitor) inhibited the increases in exon IV BDNF mRNA and CCAAT enhancer-binding protein beta (C/EBPbeta) levels induced by ET-1. The ET-induced increases in exon III BDNF mRNA expression and phosphorylation of cAMP response element binding protein (CREB) were reduced by Ca(2+) chelation, W-7, KN93, PD98059 (a MEK inhibitor), and wortmannin (a phosphatidylinositol 3-kinase inhibitor). These results suggest that ETs stimulate the expressions of exon III and exon IV BDNF transcripts in astrocytes through CREB and C/EBPbeta-mediated mechanisms, respectively.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan.
| | | | | | | |
Collapse
|
36
|
Iandiev I, Uhlmann S, Pietsch UC, Biedermann B, Reichenbach A, Wiedemann P, Bringmann A. Endothelin receptors in the detached retina of the pig. Neurosci Lett 2005; 384:72-5. [PMID: 15885900 DOI: 10.1016/j.neulet.2005.04.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 04/08/2005] [Accepted: 04/16/2005] [Indexed: 11/28/2022]
Abstract
Endothelin-1 (ET-1) is a potent vasoconstrictor that causes hypoperfusion of the neurosensory retina. We investigated immunohistochemically the expression of the receptors for ET-1, ET(A) and ET(B), in control and locally detached retinas of the pig. Immunoreactivity for ET(A) was expressed in the innermost retinal layers and in the outer plexiform layer in control retinas, and was additionally strongly expressed by retinal blood vessels at 7 days after detachment of the sensory retina from the pigment epithelium. Immunoreactivity for ET(B) was expressed by the innermost retinal layers, by ganglion cell somata, and by Müller glial cells in the control tissue, and was not altered in its expression after detachment. The vascular expression of ET(A) may suggest a hypoperfusion of the retina after detachment.
Collapse
Affiliation(s)
- Ianors Iandiev
- Paul Flechsig Institute of Clinical Brain Research, University of Leipzig Medical Faculty, D-04109 Leipzig, Germany
| | | | | | | | | | | | | |
Collapse
|
37
|
Abstract
Astrocytes become activated (reactive) in response to many CNS pathologies, such as stroke, trauma, growth of a tumor, or neurodegenerative disease. The process of astrocyte activation remains rather enigmatic and results in so-called "reactive gliosis," a reaction with specific structural and functional characteristics. In stroke or in CNS trauma, the lesion itself, the ischemic environment, disrupted blood-brain barrier, the inflammatory response, as well as in metabolic, excitotoxic, and in some cases oxidative crises--all affect the extent and quality of reactive gliosis. The fact that astrocytes function as a syncytium of interconnected cells both in health and in disease, rather than as individual cells, adds yet another dimension to this picture. This review focuses on several aspects of astrocyte activation and reactive gliosis and discusses its possible roles in the CNS trauma and ischemia. Particular emphasis is placed on the lessons learnt from mouse genetic models in which the absence of intermediate filament proteins in astrocytes leads to attenuation of reactive gliosis with distinct pathophysiological and clinical consequences.
Collapse
Affiliation(s)
- Milos Pekny
- The Arvid Carlsson Institute for Neuroscience, Institute of Clinical Neuroscience, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
| | - Michael Nilsson
- The Arvid Carlsson Institute for Neuroscience, Institute of Clinical Neuroscience, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
| |
Collapse
|
38
|
Koyama Y, Matsui S, Itoh S, Osakada M, Baba A, Matsuda T. The selective Na+-Ca2+ exchange inhibitor attenuates brain edema after radiofrequency lesion in rats. Eur J Pharmacol 2005; 489:193-6. [PMID: 15087242 DOI: 10.1016/j.ejphar.2004.03.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Revised: 02/12/2004] [Accepted: 03/05/2004] [Indexed: 11/21/2022]
Abstract
2-[4-[(2,5-Difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400), a specific inhibitor of the Na+-Ca2+ exchanger, exerts cytoprotective action and reduces brain infarct volume after cerebral ischemia. We examined the effect of SEA0400 on vasogenic brain edema in rats. Histological observations showed that radiofrequency current caused brain infarct and extravasation of endogenous albumin in the brain. SEA0400 (3 and 10 mg/kg, i.v.) significantly suppressed the increase in brain water content with attenuation of Evans blue dye and sodium fluorescein extravasation after radiofrequency lesion. The findings suggest that the Na+-Ca2+ exchanger plays a role in vasogenic edema formation after radiofrequency lesion.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565-0871, Japan
| | | | | | | | | | | |
Collapse
|
39
|
Wilhelmsson U, Li L, Pekna M, Berthold CH, Blom S, Eliasson C, Renner O, Bushong E, Ellisman M, Morgan TE, Pekny M. Absence of glial fibrillary acidic protein and vimentin prevents hypertrophy of astrocytic processes and improves post-traumatic regeneration. J Neurosci 2005; 24:5016-21. [PMID: 15163694 PMCID: PMC6729371 DOI: 10.1523/jneurosci.0820-04.2004] [Citation(s) in RCA: 337] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The regenerative capacity of the CNS is extremely limited. The reason for this is unclear, but glial cell involvement has been suspected, and oligodendrocytes have been implicated as inhibitors of neuroregeneration (Chen et al., 2000, GrandPre et al., 2000; Fournier et al., 2001). The role of astrocytes in this process was proposed but remains incompletely understood (Silver and Miller, 2004). Astrocyte activation (reactive gliosis) accompanies neurotrauma, stroke, neurodegenerative diseases, or tumors. Two prominent hallmarks of reactive gliosis are hypertrophy of astrocytic processes and upregulation of intermediate filaments. Using the entorhinal cortex lesion model in mice, we found that reactive astrocytes devoid of the intermediate filament proteins glial fibrillary acidic protein and vimentin (GFAP-/-Vim-/-), and consequently lacking intermediate filaments (Colucci-Guyon et al., 1994; Pekny et al., 1995; Eliasson et al., 1999), showed only a limited hypertrophy of cell processes. Instead, many processes were shorter and not straight, albeit the volume of neuropil reached by a single astrocyte was the same as in wild-type mice. This was accompanied by remarkable synaptic regeneration in the hippocampus. On a molecular level, GFAP-/-Vim-/- reactive astrocytes could not upregulate endothelin B receptors, suggesting that the upregulation is intermediate filament dependent. These findings show a novel role for intermediate filaments in astrocytes and implicate reactive astrocytes as potent inhibitors of neuroregeneration.
Collapse
Affiliation(s)
- Ulrika Wilhelmsson
- Department of Medical Biochemistry, Sahlgrenska Academy at Göteborg University, SE-405 30 Göteborg, Sweden
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Abstract
Astroglial cells are the most abundant cells in the mammalian central nervous system (CNS), yet our knowledge about their function in health and disease has been limited. This review focuses on the recent work addressing the function of intermediate filaments in astroglial cells under severe mechanical or osmotic stress, in hypoxia, and in brain and spinal cord injury. Recent data show that when astrocyte intermediate filaments are genetically ablated in mice, reactive gliosis is attenuated and the course of several CNS pathologies is altered, while the signs of CNS regeneration become more prominent. GFAP is the principal astrocyte intermediate filament protein and dominant mutations in the GFAP gene have been shown to lead to Alexander disease, a fatal neurodegenerative condition in humans.
Collapse
Affiliation(s)
- Milos Pekny
- Department of Medical Biochemistry, Sahlgrenska Academy at Göteborg University, Box 430, 405 30 Göteborg, Sweden.
| | | |
Collapse
|
41
|
Koyama Y, Yoshioka Y, Matsuda T, Baba A. Focal adhesion kinase is required for endothelin-induced cell cycle progression of cultured astrocytes. Glia 2003; 43:185-9. [PMID: 12838510 DOI: 10.1002/glia.10240] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
When the brain is damaged, astrocytes often cause hyperplasia resulting in glial scar formation at the injured sites. Endothelins (ETs) have been shown to be involved in the pathophysiologic responses of astrocytes, including proliferation. In this study, we examined the mechanisms underlying the ET-induced astrocytic G1/S-phase cell cycle transition by focusing on focal adhesion kinase (FAK). A transient transfection with wild-type FAK was followed by an increase in bromodeoxyuridine (BrdU) incorporation into cultured rat astrocytes. The increases in BrdU incorporation induced by 100 nM ET-1 were not found in astrocytes transfected with dominant-negative FAK mutants (FRNK and dC14-FAK). The increases in BrdU incorporation induced by 10 nM phorbol 12-myristate 13-acetate (PMA) were not affected by the FAK mutants. Wild-type FAK did not induce stress fiber formation in cultured astrocytes. The dominant negative FAK mutant dC14-FAK did not prevent ET-induced astrocytic stress fiber formation. These results suggest that FAK mediated the astrocytic G1/S cell cycle transition induced by ET-1 downstream of the cytoskeletal actin reorganization.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan
| | | | | | | |
Collapse
|
42
|
Koyama Y, Tsujikawa K, Matsuda T, Baba A. Intracerebroventricular administration of an endothelin ETB receptor agonist increases expressions of GDNF and BDNF in rat brain. Eur J Neurosci 2003; 18:887-94. [PMID: 12925014 DOI: 10.1046/j.1460-9568.2003.02797.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Endothelins (ETs) are suggested to be involved in functional alterations of astrocytes after brain injury, including proliferation, hypertrophy and production of neurotrophic factors. In this study, effects of Ala1,3,11,15-endothelin-1 (Ala1,3,11,15-ET-1), an ETB receptor selective agonist, on neurotrophic factor production were examined in rat brain. A continuous intracerebroventricular administration of Ala1,3,11,15-ET-1 (500 pmol/day for 7 days) increased the numbers of GFAP- and vimentin-positive astrocytes in the hippocampus, caudate putamen and cerebrum. Ala1,3,11,15-ET-1 did not induce neuronal degeneration and activation of microglia/macrophage in these brain regions. The intracerebroventricular administration of Ala1,3,11,15-ET-1 for 7 days caused two- to three-fold increases in glial cell line-derived neurotrophic factors (GDNF) mRNA in the hippocampus and cerebrum. The mRNA levels of brain-derived neurotrophic factors (BDNF) in caudate putamen were increased by Ala1,3,11,15-ET-1. Expressions of nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) mRNA in these regions were not largely affected by Ala1,3,11,15-ET-1, except cerebral NGF mRNA level was increased. The Ala1,3,11,15-ET-1-induced increases in GDNF and BDNF mRNA levels were accompanied by increases in immunoreactive GDNF and BDNF. Immunohistochemical observations showed that GFAP-positive astrocytes expressed GDNF and BDNF in the brain regions of Ala1,3,11,15-ET-1-infused rats. In cultured rat astrocytes, Ala1,3,11,15-ET-1 (100 nm) increased mRNA levels of GDNF and BDNF. These results suggest that activation of brain ETB receptors induced GDNF and BDNF expression in astrocytes.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-Oka 1-6 Suita, Osaka 565-0871, Japan
| | | | | | | |
Collapse
|
43
|
Peters CM, Rogers SD, Pomonis JD, Egnaczyk GF, Keyser CP, Schmidt JA, Ghilardi JR, Maggio JE, Mantyh PW, Egnazyck GF. Endothelin receptor expression in the normal and injured spinal cord: potential involvement in injury-induced ischemia and gliosis. Exp Neurol 2003; 180:1-13. [PMID: 12668144 DOI: 10.1016/s0014-4886(02)00023-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The endothelins (ETs) are a family of peptides that exert their biological effects via two distinct receptors, the endothelin A receptor (ET(A)R) and the endothelin B receptor (ET(B)R). To more clearly define the potential actions of ETs following spinal cord injury, we used immunohistochemistry and confocal microscopy to examine the protein expression of ET(A)R and ET(B)R in the normal and injured rat spinal cord. In the normal spinal cord, ET(A)R immunoreactivity (IR) is expressed by vascular smooth muscle cells and a subpopulation of primary afferent nerve fibers. ET(B)R-IR is expressed primarily by radial glia, a small population of gray and white matter astrocytes, ependymal cells, vascular endothelial cells, and to a lesser extent in smooth muscle cells. Fourteen days following compression injury to the spinal cord, there was a significant upregulation in both the immunoexpression and number of astrocytes expressing the ET(B)R in both gray and white matter and a near disappearance of ET(B)R-IR in ependymal cells and ET(A)R-IR in primary afferent fibers. Conversely, the vascular expression of ET(A)R and ET(B)R did not appear to change. As spinal cord injury has been shown to induce an immediate increase in plasma ET levels and a sustained increase in tissue ET levels, ETs would be expected to induce an initial marked vasoconstriction via activation of vascular ET(A)R/ET(B)R and then days later a glial hypertrophy via activation of the ET(B)R expressed by astrocytes. Strategies aimed at blocking vascular ET(A)R/ET(B)R and astrocyte ET(B)Rs following spinal cord injury may reduce the resulting ischemia and astrogliosis and in doing so increase neuronal survival, regeneration, and function.
Collapse
MESH Headings
- Animals
- Disease Models, Animal
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Female
- Gliosis/etiology
- Gliosis/pathology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Neuroglia/metabolism
- Neuroglia/pathology
- Rats
- Rats, Sprague-Dawley
- Receptor, Endothelin A
- Receptor, Endothelin B
- Receptors, Endothelin/biosynthesis
- Spinal Cord/metabolism
- Spinal Cord/pathology
- Spinal Cord Injuries/complications
- Spinal Cord Injuries/metabolism
- Spinal Cord Injuries/pathology
- Spinal Cord Ischemia/etiology
- Spinal Cord Ischemia/pathology
Collapse
Affiliation(s)
- Christopher M Peters
- Department of Preventive Science, University of Minnesota, Minneapolis, MN 55455, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Rogers SD, Peters CM, Pomonis JD, Hagiwara H, Ghilardi JR, Mantyh PW. Endothelin B receptors are expressed by astrocytes and regulate astrocyte hypertrophy in the normal and injured CNS. Glia 2003; 41:180-90. [PMID: 12509808 DOI: 10.1002/glia.10173] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ability of mammalian central nervous system (CNS) neurons to survive and/or regenerate following injury is influenced by surrounding glial cells. To identify the factors that control glial cell function following CNS injury, we have focused on the endothelin B receptor (ET(B)R), which we show is expressed by the majority of astrocytes that are immunoreactive for glial acid fibrillary protein (GFAP) in both the normal and crushed rabbit optic nerve. Optic nerve crush induces a marked increase in ET(B)R and GFAP immunoreactivity (IR) without inducing a significant increase in the number of GFAP-IR astrocytes, suggesting that the crush-induced astrogliosis is due primarily to astrocyte hypertrophy. To define the role that endothelins play in driving this astrogliosis, artificial cerebrospinal fluid (CSF), ET-1 (an ET(A)R and ET(B)R agonist), or Bosentan (a mixed ET(A)R and ET(B)R antagonist) were infused via osmotic minipumps into noninjured and crushed optic nerves for 14 days. Infusion of ET-1 induced a hypertrophy of ET(B)R/GFAP-IR astrocytes in the normal optic nerve, with no additional hypertrophy in the crushed nerve, whereas infusion of Bosentan induced a significant decrease in the hypertrophy of ET(B)R/GFAP-IR astrocytes in the crushed but not in the normal optic nerve. These data suggest that pharmacological blockade of astrocyte ET(B)R receptors following CNS injury modulates glial scar formation and may provide a more permissive substrate for neuronal survival and regeneration.
Collapse
Affiliation(s)
- Scott D Rogers
- Molecular Neurobiology Laboratory, Veterans Affairs Medical Center, Minneapolis, Minnesota 55455, USA
| | | | | | | | | | | |
Collapse
|
45
|
Chuquet J, Benchenane K, Toutain J, MacKenzie ET, Roussel S, Touzani O. Selective blockade of endothelin-B receptors exacerbates ischemic brain damage in the rat. Stroke 2002; 33:3019-25. [PMID: 12468806 DOI: 10.1161/01.str.0000039401.48915.9f] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND AND PURPOSE Endothelins act through 2 receptors, namely, ET(A) and ET(B). In the cerebral circulation, ET(A) mediates marked and prolonged vasoconstriction, and its blockade increases cerebral blood flow (CBF) and reduces ischemic brain damage. However, the role of ET(B) receptors remains unclear. In this study we examined, in rats, the kinetics of expression of ET(B) and the effects of ET(B) blockade on changes in CBF and brain damage after focal cerebral ischemia and N-methyl-D-aspartate (NMDA)-induced excitotoxic injury. METHODS Rats were subjected to transient (60 minutes) focal cerebral ischemia or cortical injection of NMDA. The selective ET(B) antagonist BQ-788 was injected intracerebroventricularly 30 minutes before and 30 minutes after the onset of ischemia. Cortical perfusion was monitored by laser-Doppler flowmetry. The volume of infarction or NMDA-induced cortical lesion was assessed at 24 hours after the insult. The reverse transcription-polymerase chain reaction technique was used to assess ET(B) expression. RESULTS Cerebral ischemia failed to alter the expression of ET(B) mRNA in both acute and chronic stages. Administration of BQ-788 resulted in an increase in infarction volume (178%; P<0.05) accompanied by a decrease in residual CBF (-26.7% versus control; P<0.01). In these animals we found a positive correlation between the volume of infarction and the severity of the decrease in CBF. NMDA-induced cortical lesions were not affected by the administration of BQ-788. CONCLUSIONS Our results suggest that the ET(B) antagonist BQ-788 induces deleterious effects that are mediated by the reduction of residual blood flow after ischemia and argue that the optimal therapeutic strategy in stroke would be to target the use of selective ET(A) antagonists and not mixed ET(A)/ET(B) antagonists.
Collapse
|
46
|
Abstract
Endothelin is a vasoactive peptide that has been shown to play an important role in vascular homeostasis. Recently, endothelin and its receptors have been found in ocular tissues where it appears to have a regulatory function. Endothelin is found in both the aqueous and vitreous humors and its concentration is elevated in glaucoma patients and in animal models of glaucoma. In the current review, the authors present information about the distribution of endothelin and endothelin receptors in the eye and the ocular actions of endothelins. Specifically, endothelin/aqueous humor dynamics, endothelin/nitric oxide interactions, endothelin and ischemia, and endothelin/optic nerve head effects. Observations concerning the potential role of endothelin in glaucoma pathophysiology is presented and discussed relative to its effects on the optic nerve head and in relation to glaucoma theories.
Collapse
Affiliation(s)
- Thomas Yorio
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, North Texas Eye Research Institute, Fort Worth, Texas 76107, USA.
| | | | | |
Collapse
|
47
|
Koyama Y. [Functional alterations of astroglia on brain pathologies and their intracellular mechanisms]. Nihon Yakurigaku Zasshi 2002; 119:135-43. [PMID: 11915515 DOI: 10.1254/fpj.119.135] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
A phenotypic alteration of astroglia, "astroglial activation", is a common phenomenon observed on brain pathologies. The hypertrophy/hyperplasia of activated astroglia causes a glial scar, which prevents synaptic re-generation. In contrast, many neurotrophic substances are produced by the activated astroglia. Thus, the functional alteration of astroglia is important in tissue repair processes of the damaged CNS. Endothelins (ETs) are involved in the pathophysiological responses of the CNS. We found that injection of ETs into rat brain induced activated astroglia. A selective ETB-receptor antagonist attenuated the induction of activated astroglia. In cultured astroglia, ETs reproduce the functional alterations characterizing activated astroglia; i.e., increases in proliferation, morphological changes and stimulation of several gene transcriptions. ETs re-organized astroglial cytoskeletal actin through a small GTP-binding protein, rho, which may underlie the astroglial hypertrophy. Analysis of gene expression showed that transcriptions of neurotrophic factors (GDNF and BDNF) were stimulated by ETs. ETs stimulated astroglial proliferation by both adhesion-dependent and -independent mechanisms, where FAK and ERK plays key roles, respectively. These findings suggest important roles of ETs in the regulation of astroglial functions.
Collapse
Affiliation(s)
- Yutaka Koyama
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Science, Osaka University, Yamada-Oka, Suita 565-0871, Japan.
| |
Collapse
|
48
|
Koyama Y, Yoshioka Y, Hashimoto H, Matsuda T, Baba A. Endothelins increase tyrosine phosphorylation of astrocytic focal adhesion kinase and paxillin accompanied by their association with cytoskeletal components. Neuroscience 2001; 101:219-27. [PMID: 11068150 DOI: 10.1016/s0306-4522(00)00330-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Astrocytic endothelin receptors are involved in the appearance of activated astrocytes upon injury of the brain [Ishikawa N. et al. (1997) Eur. J. Neurosci. 9, 895-901; Koyama Y. et al. (1999) Glia 26, 268-271]. To clarify signal transduction triggered by endothelin receptors, we examined the effects of endothelins on protein tyrosine phosphorylation in cultured rat astrocytes. Endothelin-1 (1 nM) increased tyrosine phosphorylation of focal adhesion kinase and paxillin. The tyrosine phosphorylation was also induced by endothelin-1 (1 nM) and Ala(1,3,11,15)-endothelin-1 (10nM), an endothelin-B receptor agonist. BQ788 (100 nM), an endothelin-B receptor antagonist, inhibited the effects of endothelin-3. Orthovanadate (VO(4)(3-)), a tyrosine phosphatase inhibitor, but not bradykinin (1 microM), angiotensin II (100 nM), A23187 (5 microM) and phorbol 12-myristate 13-acetate (100 nM), increased tyrosine phosphorylation of focal adhesion kinase and paxillin. The tyrosine phosphorylation by endothelin-3 was not prevented by pertussis toxin, Ca(2+) chelation, protein kinase C inhibitors (calphostin C and staurosporine) or wortmannin. Immunocytochemical staining showed that endothelin-3 and VO(4)(3-) induced redistribution of focal adhesion kinase and paxillin to focal adhesions concomitant with stress fiber formation in dibutyryl cyclic-AMP-treated astrocytes. Treatment with endothelin-3 and VO(4)(3-) increased focal adhesion kinase and paxillin associated with astrocytic cytoskeletal fraction. In the presence of cytochalasin B, an actin disrupting agent, endothelin-3 and VO(4)(3-) did not phosphorylate focal adhesion kinase and paxillin. Application of cytochalasin B after treatment with endothelin-3 and VO(4)(3-) stimulated dephosphorylation of focal adhesion kinase and paxillin. These results suggest that the associations of focal adhesion kinase and paxillin with cytoskeletal components are required in the endothelin-induced tyrosine phosphorylation of the astrocytic proteins.
Collapse
Affiliation(s)
- Y Koyama
- Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-Oka 1-6, Suita 565-0871, Japan
| | | | | | | | | |
Collapse
|
49
|
Ho MC, Lo AC, Kurihara H, Yu AC, Chung SS, Chung SK. Endothelin-1 protects astrocytes from hypoxic/ischemic injury. FASEB J 2001; 15:618-26. [PMID: 11259380 DOI: 10.1096/fj.99-1022com] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Under pathological conditions such as ischemia (I), subarachnoid hemorrhage, and Alzheimer's disease, astrocytes show a large increase in endothelin (ET) -like immunoreactivity. However, it is not clear whether ET is protective or destructive to these cells during brain injury. Using astrocytes from ET-1-deficient mice, we determined the effect of ET-1 on these cells under normal, hypoxic (H), and hypoxic/ischemic (H/I) conditions. Under normal culture conditions, astrocytes from wild-type and ET-1-deficient mice showed no difference in their morphology and cell proliferation rates. ET-3 and ETA receptor mRNAs were up-regulated whereas ETB receptor mRNA was down-regulated in ET-1-deficient astrocytes, suggesting that ET-1 and ET-3 may complement each other's functions and that the expressions of these endothelins and their receptors are regulated by a complex feedback mechanism. Under H and H/I conditions, ET-1 peptide and mRNA were up-regulated in wild-type astrocytes, and the astrocytes without ET-1 died faster than the wild-type astrocytes, as indicated by greater efflux of lactate dehydrogenase. The present study suggests that astrocytes without ET-1 are more vulnerable to H and H/I injuries and that the up-regulation of astrocytic ET-1 is essential for the survival of astrocytes.
Collapse
Affiliation(s)
- M C Ho
- Institute of Molecular Biology, The University of Hong Kong, Pokfulam
| | | | | | | | | | | |
Collapse
|
50
|
Nakagomi S, Kiryu-Seo S, Kiyama H. Endothelin-converting enzymes and endothelin receptor B messenger RNAs are expressed in different neural cell species and these messenger RNAs are coordinately induced in neurons and astrocytes respectively following nerve injury. Neuroscience 2001; 101:441-9. [PMID: 11074166 DOI: 10.1016/s0306-4522(00)00345-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
There is some evidence that endothelins may be a signal mediator between neuronal and glial cells, at least in some regions of the brain. To evaluate this possibility, the localization of messenger RNAs for endothelin-converting enzymes and endothelin receptor B in the rat brain were examined using in situ hybridization histochemistry. The messenger RNAs for endothelin-converting enzyme-1 and endothelin-converting enzyme-2 were expressed mainly in neurons located in various brain regions, whereas the messenger RNA for endothelin receptor B was mainly localized in the astrocytes located throughout the brainstem, Bergmann glia, choroid plexus and ependymal cells. The localization patterns of endothelin-converting enzyme and endothelin receptor B messenger RNAs were strikingly different. For instance, in the cerebellum, endothelin-converting enzyme-1 messenger RNA was localized in Purkinje cells, and endothelin-converting enzyme-2 mRNA was expressed in Purkinje cells and granule cells. On the other hand, endothelin receptor B messenger RNA was expressed in Bergmann glia and the astrocytes located in the granule cell layer. This suggests that final cleavages of big endothelins are performed on neuronal cells, and the major target of the processed endothelins could be astrocytes, which express endothelin receptor B most abundantly in the brain. Since evidence that endothelin is implicated in brain injury has also accumulated, we examined whether the expressions of endothelin-converting enzymes and endothelin receptor B are regulated by nerve injury. Following hypoglossal nerve injury, expression of messenger RNA for endothelin-converting enzymes-1 and -2 and endothelin receptor B was enhanced in the injured motor neurons and astrocytes respectively. The up-regulation of these messenger RNAs was also confirmed by a reverse transcription-polymerase chain reaction based strategyThese results lead us to suggest that endothelin can be an inducible intercellular mediator between injured neurons and astrocytes in response to nerve injury.
Collapse
Affiliation(s)
- S Nakagomi
- Department of Anatomy, Asahikawa Medical College, Midorigaoka-Higashi, Hokkaido 078-8510, Asahikawa, Japan
| | | | | |
Collapse
|