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Edvinsson L, Krause DN. Switching Off Vascular MAPK Signaling: A Novel Strategy to Prevent Delayed Cerebral Ischemia Following Subarachnoid Hemorrhage. Transl Stroke Res 2024:10.1007/s12975-024-01234-z. [PMID: 38334872 DOI: 10.1007/s12975-024-01234-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/10/2024]
Abstract
Patients who initially survive the rupture and repair of a brain aneurysm often take a devastating turn for the worse some days later and die or suffer permanent neurologic deficits. This catastrophic sequela is attributed to a delayed phase of global cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH), but we lack effective treatment. Here we present our view, based on 20 years of research, that the initial drop in blood flow at the time of rupture triggers genomic responses throughout the brain vasculature that manifest days later as increased vasoconstriction and decreased cerebral blood flow. We propose a novel treatment strategy to prevent DCI by early inhibition of the vascular mitogen-activated protein kinase (MAPK) pathway that triggers expression of vasoconstrictor and inflammatory mediators. We summarize evidence from experimental SAH models showing early treatment with MAPK inhibitors "switches off" these detrimental responses, maintains flow, and improves neurological outcome. This promising therapy is currently being evaluated in clinical trials.
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Affiliation(s)
- Lars Edvinsson
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Sölvegatan 19, 22100, Lund, Sweden.
- Department of Experimental Research, Glostrup Research Institute, CopenhagenUniversity, Copenhagen, Denmark.
| | - Diana N Krause
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Sölvegatan 19, 22100, Lund, Sweden
- Department of Pharmaceutical Sciences, SchoolofPharmacy&PharmaceuticalSciences, University of California at Irvine, Irvine, CA, USA
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Bömers JP, Grell AS, Edvinsson L, Johansson SE, Haanes KA. The MEK Inhibitor Trametinib Improves Outcomes following Subarachnoid Haemorrhage in Female Rats. Pharmaceuticals (Basel) 2022; 15:ph15121446. [PMID: 36558896 PMCID: PMC9785726 DOI: 10.3390/ph15121446] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/18/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022] Open
Abstract
Aneurysmal subarachnoid haemorrhage (SAH) is a haemorrhagic stroke that causes approximately 5% of all stroke incidents. We have been working on a treatment strategy that targets changes in cerebrovascular contractile receptors, by blocking the MEK/ERK1/2 signalling pathway. Recently, a positive effect of trametinib was found in male rats, but investigations of both sexes in pre-clinical studies are an important necessity. In the current study, a SAH was induced in female rats, by autologous blood-injection into the pre-chiasmatic cistern. This produces a dramatic, transient increase in intracranial pressure (ICP) and an acute and prolonged decrease in cerebral blood flow. Rats were then treated with either vehicle or three doses of 0.5 mg/kg trametinib (specific MEK/ERK1/2 inhibitor) intraperitoneally at 3, 9, and 24 h after the SAH. The outcome was assessed by a panel of tests, including intracranial pressure (ICP), sensorimotor tests, a neurological outcome score, and myography. We observed a significant difference in arterial contractility and a reduction in subacute increases in ICP when the rats were treated with trametinib. The sensory motor and neurological outcomes in trametinib-treated rats were significantly improved, suggesting that the improved outcome in females is similar to that of males treated with trametinib.
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Affiliation(s)
- Jesper Peter Bömers
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital—Rigshospitalet, Nordstjernevej 42, DK-2600 Glostrup, Denmark
- Department of Neurosurgery, Copenhagen University Hospital—Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
| | - Anne-Sofie Grell
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital—Rigshospitalet, Nordstjernevej 42, DK-2600 Glostrup, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital—Rigshospitalet, Nordstjernevej 42, DK-2600 Glostrup, Denmark
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, 221 84 Lund, Sweden
| | - Sara Ellinor Johansson
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital—Rigshospitalet, Nordstjernevej 42, DK-2600 Glostrup, Denmark
| | - Kristian Agmund Haanes
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital—Rigshospitalet, Nordstjernevej 42, DK-2600 Glostrup, Denmark
- Correspondence:
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Khey KMW, Huard A, Mahmoud SH. Inflammatory Pathways Following Subarachnoid Hemorrhage. Cell Mol Neurobiol 2019; 40:675-693. [PMID: 31808009 DOI: 10.1007/s10571-019-00767-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 11/23/2019] [Indexed: 02/07/2023]
Abstract
Aneurysmal subarachnoid hemorrhage (SAH) is an acute cerebrovascular emergency resulting from the rupture of a brain aneurysm. Despite only accounting for 5% of all strokes, SAH imposes a significant health burden on society due to its relatively young age at onset. Those who survive the initial bleed are often afflicted with severe disabilities thought to result from delayed cerebral ischemia (DCI). Consequently, elucidating the underlying mechanistic pathways implicated in DCI development following SAH remains a priority. Neuroinflammation has recently been implicated as a promising new theory for the development of SAH complications. However, despite this interest, clinical trials have failed to provide consistent evidence for the use of anti-inflammatory agents in SAH patients. This may be explained by the complexity of SAH as a plethora of inflammatory pathways have been shown to be activated in the disease. By determining how these pathways may overlap and interact, we hope to better understand the developmental processes of SAH complications and how to prevent them. The goal of this review is to provide insight into the available evidence regarding the molecular pathways involved in the development of inflammation following SAH and how SAH complications may arise as a result of these inflammatory pathways.
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Affiliation(s)
- Kevin Min Wei Khey
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Alec Huard
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Sherif Hanafy Mahmoud
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada.
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Christensen ST, Johansson SE, Radziwon-Balicka A, Warfvinge K, Haanes KA, Edvinsson L. MEK1/2 inhibitor U0126, but not nimodipine, reduces upregulation of cerebrovascular contractile receptors after subarachnoid haemorrhage in rats. PLoS One 2019; 14:e0215398. [PMID: 30978262 PMCID: PMC6461292 DOI: 10.1371/journal.pone.0215398] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/02/2019] [Indexed: 12/19/2022] Open
Abstract
Vascular pathophysiological changes after haemorrhagic stroke, such as phenotypic modulation of the cerebral arteries and cerebral vasospasms, are associated with delayed cerebral ischemia (DCI) and poor outcome. The only currently approved drug treatment shown to reduce the risk of DCI and improve neurologic outcome after aneurysmal subarachnoid haemorrhage (SAH) is nimodipine, a dihydropyridine L-type voltage-gated Ca2+ channel blocker. MEK1/2 mediated transcriptional upregulation of contractile receptors, including endothelin-1 (ET-1) receptors, has previously been shown to be a factor in the pathology of SAH. The aim of the study was to compare intrathecal and subcutaneous treatment regimens of nimodipine and intrathecal treatment regimens of U0126, a MEK1/2 inhibitor, in a single injection experimental rat SAH model with post 48 h endpoints consisting of wire myography of cerebral arteries, flow cytometry of cerebral arterial tissue and behavioural evaluation. Following ET-1 concentration-response curves, U0126 exposed arteries had a significantly lower ET-1max than vehicle arteries. Arteries from both the intrathecal- and subcutaneous nimodipine treated animals had significantly higher ET-1max contractions than the U0126 arteries. Furthermore, Ca2+ concentration response curves (precontracted with ET-1 and in the presence of nimodipine) showed that nimodipine treatment could result in larger nimodipine insensitive contractions compared to U0126. Flow cytometry showed decreased protein expression of the ETB receptor in U0126 treated cerebral vascular smooth muscle cells compared to vehicle. Only U0126 treatment lowered ET-1max contractions and ETB receptor levels, as well as decreased the contractions involving nimodipine-insensitive Ca2+ channels, when compared to both intrathecal and subcutaneous nimodipine treatment. This indicate that targeting gene expression might be a better strategy than blocking specific receptors or ion channels in future treatments of SAH.
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Affiliation(s)
- Simon T. Christensen
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
| | - Sara E. Johansson
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
| | - Aneta Radziwon-Balicka
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
| | - Karin Warfvinge
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden
| | - Kristian A. Haanes
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
- * E-mail:
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Copenhagen University Hospital, Rigshospitalet-Glostrup, Denmark
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden
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The Acute Phase of Experimental Subarachnoid Hemorrhage: Intracranial Pressure Dynamics and Their Effect on Cerebral Blood Flow and Autoregulation. Transl Stroke Res 2018; 10:566-582. [PMID: 30443885 DOI: 10.1007/s12975-018-0674-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/11/2018] [Accepted: 11/07/2018] [Indexed: 02/07/2023]
Abstract
Clinical presentation and neurological outcome in subarachnoid hemorrhage (SAH) is highly variable. Aneurysmal SAH (aSAH) is hallmarked by sudden increase of intracranial pressure (ICP) and acute hypoperfusion contributing to early brain injury (EBI) and worse outcome, while milder or non-aneurysmal SAH with comparable amount of blood are associated with better neurological outcome, possibly due to less dramatic changes in ICP. Acute pressure dynamics may therefore be an important pathophysiological aspect determining neurological complications and outcome. We investigated the influence of ICP variability on acute changes after SAH by modulating injection velocity and composition in an experimental model of SAH. Five hundred microliters of arterial blood (AB) or normal saline (NS) were injected intracisternally over 1 (AB1, NS1), 10 (AB10, NS10), or 30 min (AB30) with monitoring for 6 h (n = 68). Rapid blood injection resulted in highest ICP peaks (AB1 median 142.7 mmHg [1.Q 116.7-3.Q 230.6], AB30 33.42 mmHg [18.8-38.3], p < 0.001) and most severe hypoperfusion (AB1 16.6% [11.3-30.6], AB30 44.2% [34.8-59.8]; p < 0.05). However, after 30 min, all blood groups showed comparable ICP elevation and prolonged hypoperfusion. Cerebral autoregulation was disrupted initially due to the immediate ICP increase in all groups except NS10; only AB1, however, resulted in sustained impairment of autoregulation, as well as early neuronal cell loss. Rapidity and composition of hemorrhage resulted in characteristic hyperacute hemodynamic changes, with comparable hypoperfusion despite different ICP ranges. Only rapid ICP increase was associated with pronounced and early, but sustained disruption of cerebral autoregulation, possibly contributing to EBI.
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Stanfill A, Simpson C, Sherwood P, Poloyac S, Crago E, Kim H, Conley Y. A pilot study on the impact of dopamine, serotonin, and brain-derived neurotrophic factor genotype on long-term functional outcomes after subarachnoid hemorrhage. SAGE Open Med 2017; 5:2050312117726725. [PMID: 28894586 PMCID: PMC5582657 DOI: 10.1177/2050312117726725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 07/23/2017] [Indexed: 12/01/2022] Open
Abstract
Objectives: Many that survive an aneurysmal subarachnoid hemorrhage experience lasting physical disability, which might be improved by medications with effects on the dopaminergic, serotonergic, and brain-derived neurotrophic factor neurotransmitter systems. But it is not clear which patients are most likely to benefit from these therapies. The purpose of this pilot study was to explore the relationship of genetic polymorphisms in these pathways with 12-month functional outcomes after aneurysmal subarachnoid hemorrhage. Methods: Subjects were recruited at the time of admission as a part of a larger parent study. Genotypes were generated using the Affymetrix genome-wide human single-nucleotide polymorphism array 6.0. Those within dopaminergic, serotonergic, and brain-derived neurotrophic factor pathways were analyzed for associations with functional outcomes at 12 months post aneurysmal subarachnoid hemorrhage using the Glasgow Outcome Scale and the Modified Rankin Scale. Results: The 154 subjects were 55.8 ± 11.3 years old and 74% female; they had Fisher scores of 2.95 ± 0.67, Hunt/Hess scores of 2.66 ± 1.13, and admission Glasgow Coma Scale scores of 12.52 ± 3.79. Single-nucleotide polymorphisms in the serotonin receptor genes 1B and 1E and dopamine receptor D2 were associated with greater disability (odds ratio: 3.88–3.25, confidence interval: 1.01–14.77), while single-nucleotide polymorphisms in the serotonin receptor genes 2A and 2C and dopamine receptor D5 conferred a risk of poor recovery (odds ratio: 3.31–2.32, confidence interval: 1.00–10.80). Single-nucleotide polymorphisms within the same serotonin genes, and within the dopamine receptor gene D2, were associated with greater recovery after aneurysmal subarachnoid hemorrhage (odds ratio: 0.17–0.34, confidence interval: 0.05–0.89). Conclusions: These data demonstrate that there may be an association between genetic factors and functional outcomes post stroke.
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Affiliation(s)
- Ansley Stanfill
- Acute and Tertiary Care, College of Nursing, The University of Tennessee Health Science Center, Memphis, TN, USA
- Health Promotion & Development, School of Nursing, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Genetics, Genomics and Informatics, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
- Ansley Stanfill, Acute and Tertiary Care, College of Nursing, The University of Tennessee Health Science Center, 71 Manassas St #425, Memphis, TN 38163, USA.
| | - Claire Simpson
- Department of Genetics, Genomics and Informatics, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Paula Sherwood
- Acute & Tertiary Care, School of Nursing, University of Pittsburgh, Pittsburgh, PA, USA
| | - Samuel Poloyac
- School of Pharmacy, University of Pittsburgh, Pittsburgh, PA, USA
| | - Elizabeth Crago
- Acute & Tertiary Care, School of Nursing, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hyungsuk Kim
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD, USA
| | - Yvette Conley
- Health Promotion & Development, School of Nursing, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, University of Pittsburgh, Pittsburgh, PA, USA
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Sun Y, Shen Q, Watts LT, Muir ER, Huang S, Yang GY, Suarez JI, Duong TQ. Multimodal MRI characterization of experimental subarachnoid hemorrhage. Neuroscience 2016; 316:53-62. [PMID: 26708744 PMCID: PMC4724533 DOI: 10.1016/j.neuroscience.2015.12.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 01/01/2023]
Abstract
Subarachnoid hemorrhage (SAH) is associated with significant morbidity and mortality. We implemented an in-scanner rat model of mild SAH in which blood or vehicle was injected into the cistern magna, and applied multimodal MRI to study the brain prior to, immediately after (5min to 4h), and upto 7days after SAH. Vehicle injection did not change arterial lumen diameter, apparent diffusion coefficient (ADC), T2, venous signal, vascular reactivity to hypercapnia, or foot-fault scores, but mildly reduce cerebral blood flow (CBF) up to 4h, and open-field activity up to 7days post injection. By contrast, blood injection caused: (i) vasospasm 30min after SAH but not thereafter, (ii) venous abnormalities at 3h and 2days, delayed relative to vasospasm, (iii) reduced basal CBF and to hypercapnia 1-4h but not thereafter, (iv) reduced ADC immediately after SAH but no ADC and T2 changes on days 2 and 7, and (v) reduced open-field activities in both SAH and vehicle animals, but no significant differences in open-field activities and foot-fault tests between groups. Mild SAH exhibited transient and mild hemodynamic disturbances and diffusion changes, but did not show apparent ischemic brain injury nor functional deficits.
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Affiliation(s)
- Y Sun
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Stereotactic and Functional Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Q Shen
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - L T Watts
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Department of Neurology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - E R Muir
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - S Huang
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - G-Y Yang
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Stereotactic and Functional Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Neuroscience and Neuroengineering Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200030, China
| | - J I Suarez
- Division of Vascular Neurology and Neurocritical Care, Department of Neurology, Baylor College of Medicine, Baylor St Luke's Medical Center, Houston, TX 77027, USA
| | - T Q Duong
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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Regulation of microRNAs miR-30a and miR-143 in cerebral vasculature after experimental subarachnoid hemorrhage in rats. BMC Genomics 2015; 16:119. [PMID: 25766280 PMCID: PMC4342208 DOI: 10.1186/s12864-015-1341-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 02/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND microRNAs (miRNAs) are important regulators of translation and have been implicated in the pathogenesis of a number of cardiovascular diseases, including stroke, and suggested as possible prognostic biomarkers. Our aim was to identify miRNAs that are differentially regulated in cerebral arteries after subarachnoid hemorrhage (SAH), using a rat injection model of SAH and a qPCR-based screen of 728 rat miRNAs. Additionally, serum was analyzed for a possible spill-over to the circulation of regulated miRNAs from the vessel walls. RESULTS We identified 482 different miRNAs expressed in cerebral arteries post-SAH. Two miRNAs, miR-30a and miR-143, were significantly upregulated in cerebral arteries after SAH when compared to sham-operated animals. However, none of these exhibited significantly altered serum levels after SAH versus post-sham surgery. The most robust upregulation was seen for miR-143, which has several predicted targets and is a strong regulator of vascular morphology. We hypothesize that miR-30a and miR-143 may play a role in the vascular wall changes seen after SAH. CONCLUSIONS We report that miR-30a and miR-143 in the cerebral arteries show significant changes over time after SAH, but do not differ from sham-operated rats at 24 h post-SAH. Although this finding suggests interesting novel possible mechanisms involved in post-SAH cerebrovascular changes, the lack of regulation of these miRNAs in serum excludes their use as blood-borne biomarkers for cerebrovascular changes following SAH.
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Povlsen GK, Edvinsson L. MEK1/2 inhibitor U0126 but not endothelin receptor antagonist clazosentan reduces upregulation of cerebrovascular contractile receptors and delayed cerebral ischemia, and improves outcome after subarachnoid hemorrhage in rats. J Cereb Blood Flow Metab 2015; 35:329-37. [PMID: 25407271 PMCID: PMC4426751 DOI: 10.1038/jcbfm.2014.205] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/24/2014] [Accepted: 10/24/2014] [Indexed: 02/01/2023]
Abstract
Cerebral vasospasm and late cerebral ischemia (LCI) remain leading causes of mortality in patients experiencing a subarachnoid hemorrhage (SAH). This occurs typically 3 to 4 days after the initial bleeding and peaks at 5 to 7 days. The underlying pathophysiology is still poorly understood. Because SAH is associated with elevated levels of endothelin-1 (ET-1), focus has been on counteracting endothelin receptor activation with receptor antagonists like clazosentan, however, with poor outcome in clinical trials. We hypothesize that inhibition of intracellular transcription signaling will be an effective approach to prevent LCI. Here, we compare the effects of clazosentan versus the MEK1/2 blocker U0126 in a rat model of SAH. Although clazosentan directly inhibits the contractile responses in vivo to ET-1, it did not prevent SAH-induced upregulation of ET receptors in cerebral arteries and did not show a beneficial effect on neurologic outcome. U0126 had no vasomotor effect by itself but counteracts SAH-induced receptor upregulation in cerebral arteries and improved outcome after SAH. We suggest that because SAH induces elevated expression of several contractile receptor subtypes, it is not sufficient to block only one of these (ET receptors) but inhibition of transcriptional MEK1/2-mediated upregulation of several contractile receptors may be a viable way towards alleviating LCI.
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Affiliation(s)
- Gro K Povlsen
- Department of Experimental Research, Glostrup Research Institute, Copenhagen University, Copenhagen, Denmark
| | - Lars Edvinsson
- 1] Department of Experimental Research, Glostrup Research Institute, Copenhagen University, Copenhagen, Denmark [2] Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden
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Marbacher S, Neuschmelting V, Andereggen L, Widmer HR, von Gunten M, Takala J, Jakob SM, Fandino J. Early brain injury linearly correlates with reduction in cerebral perfusion pressure during the hyperacute phase of subarachnoid hemorrhage. Intensive Care Med Exp 2014; 2:30. [PMID: 26266927 PMCID: PMC4512974 DOI: 10.1186/s40635-014-0030-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 11/07/2014] [Indexed: 02/02/2023] Open
Abstract
Background It is unclear how complex pathophysiological mechanisms that result in early brain injury (EBI) after subarachnoid hemorrhage (SAH) are triggered. We investigate how peak intracranial pressure (ICP), amount of subarachnoid blood, and hyperacute depletion of cerebral perfusion pressure (CPP) correlate to the onset of EBI following experimental SAH. Methods An entire spectrum of various degrees of SAH severities measured as peak ICP was generated and controlled using the blood shunt SAH model in rabbits. Standard cardiovascular monitoring, ICP, CPP, and bilateral regional cerebral blood flow (rCBF) were continuously measured. Cells with DNA damage and neurodegeneration were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and Fluoro-jade B (FJB). Results rCBF was significantly correlated to reduction in CPP during the initial 15 min after SAH in a linear regression pattern (r2 = 0.68, p < 0.001). FJB- and TUNEL-labeled cells were linearly correlated to reduction in CPP during the first 3 min of hemorrhage in the hippocampal regions (FJB: r2 = 0.50, p < 0.01; TUNEL: r2 = 0.35, p < 0.05), as well as in the basal cortex (TUNEL: r2 = 0.58, p < 0.01). EBI occurred in animals with severe (relative CPP depletion >0.4) and moderate (relative CPP depletion >0.25 but <0.4) SAH. Neuronal cell death was equally detected in vulnerable and more resistant brain regions. Conclusions The degree of EBI in terms of neuronal cell degeneration in both the hippocampal regions and the basal cortex linearly correlates with reduced CPP during hyperacute SAH. Temporary CPP reduction, however, is not solely responsible for EBI but potentially triggers processes that eventually result in early brain damage. Electronic supplementary material The online version of this article (doi:10.1186/s40635-014-0030-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Serge Marbacher
- Cerebrovascular Research Laboratory of the Department of Intensive Care Medicine, University Hospital and University of Bern, 3010, Bern, Switzerland,
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11
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Wang X, Chen JX, Mao Q, Liu YH, You C. Relationship between intracranial pressure and aneurysmal subarachnoid hemorrhage grades. J Neurol Sci 2014; 346:284-7. [PMID: 25245175 DOI: 10.1016/j.jns.2014.09.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 09/06/2014] [Accepted: 09/08/2014] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Intracranial pressure (ICP) is frequently elevated following aneurysmal subarachnoid hemorrhage (aSAH). In this prospective study, the factors associated with increased ICP and the relationship between ICP and the aSAH grade were evaluated. METHODS Consecutive patients with prospective aSAH were enrolled within 24h after disease onset. Clinical scoring, including the Hunt and Hess scale, the WFNS scale and the Fisher scale, was performed upon admission. Consciousness was evaluated based on the Glasgow Coma Scale, and the subarachnoid hemorrhage volume was determined according to a CT scan. Then, an ICP monitor was placed, and ICP was recorded. The relationship between ICP and the aSAH grade was examined using Spearman correlation coefficients. Additionally, some clinical characteristics of the patients, including age, sex, location and size of the aneurysm, hydrocephalus and rebleeding, were recorded and analyzed. RESULTS A total of 165 patients were enrolled in this study. Of these patients, 111 (67.2%) displayed elevated ICP (≥ 20 mm Hg). The patients who underwent intubation or who experienced rebleeding or hydrocephalus displayed an elevated ICP compared with those who did not (P = 0.002, P = 0.001 and P = 0.008, respectively). There was a positive linear correlation between ICP and both the Hunt and Hess grade and the WFNS grade (correlation coefficients of 0.731 and 0.761, respectively). The correlation between ICP and the Fisher grade was weak according to the correlation coefficient of only 0.093. CONCLUSION ICP following aSAH positively correlates with the patient's consciousness, but no relationship was detected between ICP and the subarachnoid hemorrhage volume.
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Affiliation(s)
- Xiang Wang
- Department of Neurosurgery, West China Hospital of Sichuan University, China
| | - Jin-xiu Chen
- Department of Radiology, Sichuan Cancer Hospital, China
| | - Qing Mao
- Department of Neurosurgery, West China Hospital of Sichuan University, China
| | - Yan-hui Liu
- Department of Neurosurgery, West China Hospital of Sichuan University, China
| | - Chao You
- Department of Neurosurgery, West China Hospital of Sichuan University, China.
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Edvinsson L, Larsen SS, Maddahi A, Nielsen J. Plasticity of cerebrovascular smooth muscle cells after subarachnoid hemorrhage. Transl Stroke Res 2014; 5:365-76. [PMID: 24449486 DOI: 10.1007/s12975-014-0331-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/19/2013] [Accepted: 01/06/2014] [Indexed: 12/27/2022]
Abstract
Subarachnoid hemorrhage (SAH) is most often followed by a delayed phase of cerebral ischemia which is associated with high morbidity and mortality rates. The causes underlying this delayed phase are still unsettled, but are believed to include cerebral vasospasm, cortical spreading depression, inflammatory reactions, and microthrombosis. Additionally, a large body of evidence indicates that vascular plasticity plays an important role in SAH pathophysiology, and this review aims to summarize our current knowledge on the phenotypic changes of vascular smooth muscle cells of the cerebral vasculature following SAH. In light of the emerging view that the whole cerebral vasculature and the cells of the brain parenchyma should be viewed as one integrated neurovascular network, phenotypical changes are discussed both for the cerebral arteries and the microvasculature. Furthermore, the intracellular signaling involved in the vascular plasticity is discussed with a focus on the Raf-MEK1/2-ERK1/2 pathway which seems to play a crucial role in SAH pathology.
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Affiliation(s)
- Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Glostrup, Denmark,
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Povlsen GK, Johansson SE, Larsen CC, Samraj AK, Edvinsson L. Early events triggering delayed vasoconstrictor receptor upregulation and cerebral ischemia after subarachnoid hemorrhage. BMC Neurosci 2013; 14:34. [PMID: 23496889 PMCID: PMC3618233 DOI: 10.1186/1471-2202-14-34] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 03/07/2013] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Upregulation of vasoconstrictor receptors in cerebral arteries, including endothelin B (ETB) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors, has been suggested to contribute to delayed cerebral ischemia, a feared complication after subarachnoid hemorrhage (SAH). This receptor upregulation has been shown to be mediated by intracellular signalling via the mitogen activated protein kinase kinase (MEK1/2)--extracellular regulated kinase 1/2 (ERK1/2) pathway. However, it is not known what event(s) that trigger MEK-ERK1/2 activation and vasoconstrictor receptor upregulation after SAH.We hypothesise that the drop in cerebral blood flow (CBF) and wall tension experienced by cerebral arteries in acute SAH is a key triggering event. We here investigate the importance of the duration of this acute CBF drop in a rat SAH model in which a fixed amount of blood is injected into the prechiasmatic cistern either at a high rate resulting in a short acute CBF drop or at a slower rate resulting in a prolonged acute CBF drop. RESULTS We demonstrate that the duration of the acute CBF drop is determining for a) degree of early ERK1/2 activation in cerebral arteries, b) delayed upregulation of vasoconstrictor receptors in cerebral arteries and c) delayed CBF reduction, neurological deficits and mortality. Moreover, treatment with an inhibitor of MEK-ERK1/2 signalling during an early time window from 6 to 24 h after SAH was sufficient to completely prevent delayed vasoconstrictor receptor upregulation and improve neurological outcome several days after the SAH. CONCLUSIONS Our findings suggest a series of events where 1) the acute CBF drop triggers early MEK-ERK1/2 activation, which 2) triggers the transcriptional upregulation of vasoconstrictor receptors in cerebral arteries during the following days, where 3) the resulting enhanced cerebrovascular contractility contribute to delayed cerebral ischemia.
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Affiliation(s)
- Gro Klitgaard Povlsen
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Nordre Ringvej 69, Glostrup, DK 2600, Denmark
| | - Sara Ellinor Johansson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Nordre Ringvej 69, Glostrup, DK 2600, Denmark
| | | | - Ajoy Kumar Samraj
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Nordre Ringvej 69, Glostrup, DK 2600, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Glostrup University Hospital, Nordre Ringvej 69, Glostrup, DK 2600, Denmark
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Ahnstedt H, Stenman E, Cao L, Henriksson M, Edvinsson L. Cytokines and growth factors modify the upregulation of contractile endothelin ET(A) and ET(B) receptors in rat cerebral arteries after organ culture. Acta Physiol (Oxf) 2012; 205:266-78. [PMID: 22145714 DOI: 10.1111/j.1748-1716.2011.02392.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 09/20/2011] [Accepted: 11/30/2011] [Indexed: 11/30/2022]
Abstract
AIM Experimental cerebral ischaemia and organ culture of cerebral arteries induce an increased endothelin ET(B) receptor-mediated contraction. The aim of this study was to examine whether cytokines and growth factors, known to be activated in ischaemia, can influence the expression and function of endothelin receptors after organ culture. METHODS Rat middle cerebral arteries were cultured for 24 h at 37 °C in humidified 5% CO(2) and air in culture medium alone, or with tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), platelet-derived growth factor (PDGF), epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF). Concentration-response curves were obtained for sarafotoxin 6c (ET(B) receptor agonist) and endothelin-1 (here ET(A) receptor agonist, because of ET(B) receptor desensitization). The receptor mRNA expression was examined by real-time PCR and the protein expression by immunohistochemistry and Western blot. RESULTS Tumour necrosis factor-α (100 ng mL(-1) ) and EGF (20 ng mL(-1) ) potentiated the ET(B) receptor-mediated contraction (increase in pEC(50) without change in E(max) ). bFGF (10 ng mL(-1) ) and IL-1β (10 ng mL(-1) ) induced an enhanced ET(A) receptor-mediated contraction. bFGF (10 ng mL(-1) ) significantly increased the ET(B) mRNA level, and EGF (20 ng mL(-1) ) increased the ET(A) receptor protein. Increased ET(B) receptor mRNA and protein level also were observed after treatment with IL-1β (10 ng mL(-1) ). CONCLUSION This study shows that TNF-α, IL-1β, EGF and bFGF can modify the expression and function of endothelin receptors during organ culture. Because there is similar receptor upregulation in experimental stroke, the effect of cytokines and growth factors on endothelin receptor upregulation is an interesting aspect to study in vivo.
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Affiliation(s)
- H. Ahnstedt
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - E. Stenman
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - L. Cao
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - M. Henriksson
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
| | - L. Edvinsson
- Division of Experimental Vascular Research; Department of Clinical Sciences; Lund University; Lund; Sweden
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Inhibition of cerebrovascular raf activation attenuates cerebral blood flow and prevents upregulation of contractile receptors after subarachnoid hemorrhage. BMC Neurosci 2011; 12:107. [PMID: 22032648 PMCID: PMC3219635 DOI: 10.1186/1471-2202-12-107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 10/27/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Late cerebral ischemia carries high morbidity and mortality after subarachnoid hemorrhage (SAH) due to reduced cerebral blood flow (CBF) and the subsequent cerebral ischemia which is associated with upregulation of contractile receptors in the vascular smooth muscle cells (SMC) via activation of mitogen-activated protein kinase (MAPK) of the extracellular signal-regulated kinase (ERK)1/2 signal pathway. We hypothesize that SAH initiates cerebrovascular ERK1/2 activation, resulting in receptor upregulation. The raf inhibitor will inhibit the molecular events upstream ERK1/2 and may provide a therapeutic window for treatment of cerebral ischemia after SAH. RESULTS Here we demonstrate that SAH increases the phosphorylation level of ERK1/2 in cerebral vessels and reduces the neurology score in rats in additional with the CBF measured by an autoradiographic method. The intracisternal administration of SB-386023-b, a specific inhibitor of raf, given 6 h after SAH, aborts the receptor changes and protects the brain from the development of late cerebral ischemia at 48 h. This is accompanied by reduced phosphorylation of ERK1/2 in cerebrovascular SMC. SAH per se enhances contractile responses to endothelin-1 (ET-1), 5-carboxamidotryptamine (5-CT) and angiotensin II (Ang II), upregulates ETB, 5-HT1B and AT1 receptor mRNA and protein levels. Treatment with SB-386023-b given as late as at 6 h but not at 12 h after the SAH significantly decreased the receptor upregulation, the reduction in CBF and the neurology score. CONCLUSION These results provide evidence for a role of the ERK1/2 pathway in regulation of expression of cerebrovascular SMC receptors. It is suggested that raf inhibition may reduce late cerebral ischemia after SAH and provides a realistic time window for therapy.
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Edvinsson L, Povlsen GK. Late cerebral ischaemia after subarachnoid haemorrhage: is cerebrovascular receptor upregulation the mechanism behind? Acta Physiol (Oxf) 2011; 203:209-24. [PMID: 21087418 DOI: 10.1111/j.1748-1716.2010.02227.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Late cerebral ischaemia after subarachnoid haemorrhage (SAH) carries high morbidity and mortality because of reduced cerebral blood flow (CBF) and subsequent cerebral ischaemia. This is associated with upregulation of contractile receptors in cerebral artery smooth muscles via the activation of intracellular signalling. In addition, delayed cerebral ischaemia after SAH is associated with inflammation and disruption of the blood-brain barrier (BBB). This article reviews recent evidence concerning the roles of vasoconstrictor receptor upregulation, inflammation and BBB breakdown in delayed cerebral ischaemia after SAH. In addition, recent studies investigating the role of various intracellular signalling pathways in these processes and the possibilities of targeting signalling components in SAH treatment are discussed. Studies using a rat SAH model have demonstrated that cerebral arteries increase their sensitivity to endogenous agonists such as ET-1 and 5-HT by increasing their smooth muscle expression of receptors for these after SAH. This is associated with reduced CBF and neurological deficits. A number of signal transduction components mediating this receptor upregulation have been identified, including the MEK-ERK1/2 pathway. Inhibition of MEK-ERK1/2 signalling has been shown to prevent cerebrovascular receptor upregulation and normalize CBF and neurological function after SAH in rats. At the same time, in rat SAH, certain cytokines and BBB-regulating proteins are upregulated in cerebral artery smooth muscles and treatment with MEK-ERK1/2 inhibitors prevents the induction of these proteins. Thus, inhibitors of MEK-ERK1/2 signalling exert multimodal beneficial effects in SAH.
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Affiliation(s)
- L Edvinsson
- Department of Medicine, Institute of Clinical Sciences, University of Lund, Sweden.
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Dusick JR, Evans BC, Laiwalla A, Krahl S, Gonzalez NR. A minimally-invasive rat model of subarachnoid hemorrhage and delayed ischemic injury. Surg Neurol Int 2011; 2:99. [PMID: 21811705 PMCID: PMC3144598 DOI: 10.4103/2152-7806.83023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 06/28/2011] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Double-injection models of subarachnoid hemorrhage (SAH) in rats are the most effective in producing vasospasm, delayed neurological deficits and infarctions. However, they require two large surgeries to expose the femoral artery and the atlanto-occipital membrane. We have developed a minimally-invasive modification that prevents confounding effects of surgical procedures, leakage of blood from the subarachnoid space and minimizes risk of infection. METHODS Rats are anesthetized and the ventral tail artery is exposed through a small (5 mm), midline incision, 0.2 mL of blood is taken from the artery and gentle pressure is applied for hemostasis. The rat is flipped prone, and with the head flexed to 90 degrees in a stereotactic frame, a 27G angiocath is advanced in a vertical trajectory, level with the external auditory canals. Upon puncturing the atlanto-occipital membrane, the needle is slowly advanced and observed for cerebrospinal fluid (CSF). A syringe withdraws 0.1 mL of CSF and the blood is injected into the subarachnoid space. The procedure is repeated 24 hours later by re-opening the tail incision. At 8 days, the rats are euthanized and their brains harvested, sectioned, and incubated with triphenyltetrazolium chloride (TTC). RESULTS Rats develop neurological deficits consistent with vasospasm and infarction as previously described in double-injection models. Cortical and deep infarctions were demonstrated by TTC staining and on histopathology. CONCLUSIONS A minimally invasive, double-injection rat model of SAH and vasospasm is feasible and produces neurological deficits and infarction. This model can be used to study neuroprotective treatments for vasospasm and delayed neurological deficits following SAH, reducing the confounding effects of surgical interventions.
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Affiliation(s)
- Joshua R Dusick
- Department of Neurosurgery, UCLA David Geffen School of Medicine, Los Angeles, CA, USA
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Edvinsson LIH, Povlsen GK. Vascular plasticity in cerebrovascular disorders. J Cereb Blood Flow Metab 2011; 31:1554-71. [PMID: 21559027 PMCID: PMC3137480 DOI: 10.1038/jcbfm.2011.70] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 04/06/2011] [Accepted: 04/06/2011] [Indexed: 12/31/2022]
Abstract
Cerebral ischemia remains a major cause of morbidity and mortality with little advancement in subacute treatment options. This review aims to cover and discuss novel insight obtained during the last decade into plastic changes in the vasoconstrictor receptor profiles of cerebral arteries and microvessels that takes place after different types of stroke. Receptors like the endothelin type B, angiotensin type 1, and 5-hydroxytryptamine type 1B/1D receptors are upregulated in the smooth muscle layer of cerebral arteries after different types of ischemic stroke as well as after subarachnoid hemorrhage, yielding rather dramatic changes in the contractility of the vessels. Some of the signal transduction processes mediating this receptor upregulation have been elucidated. In particular the extracellular regulated kinase 1/2 pathway, which is activated early in the process, has proven to be a promising therapeutic target for prevention of vasoconstrictor receptor upregulation after stroke. Together, those findings provide new perspectives on the pathophysiology of ischemic stroke and point toward a novel way of reducing vasoconstriction, neuronal cell death, and thus neurologic deficits after stroke.
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Affiliation(s)
- Lars I H Edvinsson
- Department of Clinical Experimental Research, Copenhagen University, Glostrup Hospital Research Park, Copenhagen, Denmark.
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Blockade of the MEK/ERK pathway with a raf inhibitor prevents activation of pro-inflammatory mediators in cerebral arteries and reduction in cerebral blood flow after subarachnoid hemorrhage in a rat model. J Cereb Blood Flow Metab 2011; 31:144-54. [PMID: 20424636 PMCID: PMC3049479 DOI: 10.1038/jcbfm.2010.62] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cerebral ischemia that develops after subarachnoid hemorrhage (SAH) carries high morbidity and mortality. Inflammatory mediators are involved in the development of cerebral ischemia through activation of the mitogen-activated protein kinase pathway. We hypothesized that blockade of the MAPkinase/ERK (MEK)/extracellular signal-regulated kinase (ERK) pathway upstream with a specific raf inhibitor would prevent SAH-induced activation of the cerebrovascular inflammatory response. The raf inhibitor SB-386023-b was injected intracisternally in our rat model at 0, 6, or 12 hours after the SAH. After 48 hours, cerebral arteries were harvested, and iNOS, interleukin (IL)-6, IL-1β, matrix metalloproteinase (MMP)-9, tissue inhibitors of metalloproteinase (TIMP)-1, and phosphorylated ERK1/2 were investigated by immunofluorescence, real-time polymerase chain reaction (PCR), and Western blot analysis. Cerebral blood flow (CBF) was measured using autoradiography. Protein levels of MMP-9, TIMP-1, iNOS, IL-6, and IL-1β were increased after SAH, as were mRNA levels of IL-6, MMP-9, and TIMP-1. After SAH, pERK1/2 was increased, but CBF was reduced. Treatment with SB-386023-b at 0 or 6 hours after SAH normalized CBF and prevented SAH-induced upregulation of MMPs, pro-inflammatory cytokines, and pERK1/2 proteins. These results suggested that inhibition of MEK/ERK signal transduction by a specific raf inhibitor administered up to 6 hours after SAH normalized the expression of pro-inflammatory mediators and extracellular matrix-related genes.
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Abstract
We studied whether endothelial nitric oxide synthase (eNOS) is upregulated and uncoupled in large cerebral arteries after subarachnoid hemorrhage (SAH) and also whether this causes cerebral vasospasm in a mouse model of anterior circulation SAH. Control animals underwent injection of saline instead of blood (n=16 SAH and n=16 controls). There was significant vasospasm of the middle cerebral artery 2 days after SAH (lumen radius/wall thickness ratio 4.3 ± 1.3 for SAH, 23.2 ± 2.1 for saline, P<0.001). Subarachnoid hemorrhage was associated with terminal deoxynucleotidyl transferase dUTP nick-end labeling, cleaved caspase-3, and Fluoro-Jade-positive neurons in the cortex and with CA1 and dentate regions in the hippocampus. There were multiple fibrinogen-positive microthromboemboli in the cortex and hippocampus after SAH. Transgenic mice expressing lacZ under control of the eNOS promoter had increased X-gal staining in large arteries after SAH, and this was confirmed by the increased eNOS protein on western blotting. Evidence that eNOS was uncoupled was found in that nitric oxide availability was decreased, and superoxide and peroxynitrite concentrations were increased in the brains of mice with SAH. This study suggests that artery constriction by SAH upregulates eNOS but that it is uncoupled and produces peroxynitrite that may generate microemboli that travel distally and contribute to brain injury.
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Larsen CC, Povlsen GK, Rasmussen MNP, Edvinsson L. Improvement in neurological outcome and abolition of cerebrovascular endothelin B and 5-hydroxytryptamine 1B receptor upregulation through mitogen-activated protein kinase kinase 1/2 inhibition after subarachnoid hemorrhage in rats. J Neurosurg 2010; 114:1143-53. [PMID: 20597604 DOI: 10.3171/2010.6.jns1018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Delayed cerebral ischemia after subarachnoid hemorrhage (SAH) remains a major cause of death and disability. It has been hypothesized that cerebrovascular upregulation of vasoconstrictor receptors is a key step in the development of delayed cerebral ischemia. Upregulation of endothelin-B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated in cerebral artery smooth muscles in the delayed ischemic phase after experimental SAH, and intracellular signaling via the mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase 1/2 pathway has been shown to be involved in this upregulation. The aim in the present study was to determine whether treatment with the MEK1/2 inhibitor U0126 can prevent cerebrovascular receptor upregulation and improve functional outcome after experimental SAH in rats. METHODS Subarachnoid hemorrhage was induced in male Sprague-Dawley rats by the injection of 250 μl of autologous blood into the basal cisterns. Either U0126 or vehicle was intracisternally administered at 6, 12, 24, and 36 hours after SAH. Smooth muscle ET(B) and 5-HT(1B) receptor upregulation was studied in isolated cerebral artery segments through immunohistochemical and myographic studies of contractile responses to receptor-specific agonists. Gross sensorimotor function in the rats after SAH was assessed using a rotating pole test. RESULTS Contractile concentration-response curves for middle cerebral artery (MCA) and basilar artery (BA) segments to endothelin-1 (ET-1) and 5-carboxamidotryptamine (5-CT) were shifted leftward for SAH-induced compared with shamoperated rats due to enhanced contractile responses to individual doses of the agonists (for example, contractile responses of the BA to 3 × 10(-10) M of ET-1 and 3 × 10(-7) M of 5-CT were 9.98 ± 5.01% and 16.75 ± 3.62% of the maximal contractile capacity, respectively, in sham-operated rats and 62.78 ± 9.9% and 45.44 ± 10.62%, respectively, in SAH-induced rats). In vivo treatment with 0.19 μg/kg U0126 normalized responses in the SAH-induced rats to levels in the sham-operated rats. Protein expression of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles from SAH-induced rats was increased to 175 ± 33.17% and 167.7 ± 24.74%, respectively, of the levels in sham-operated rats. Endothelin-B and 5-HT(1B) expression levels in U0126-treated SAH-induced rats were at the levels in sham-operated rats (101.9 ± 13.38% and 91.44 ± 16.75%, respectively). In a rotating pole test used to assess gross sensorimotor function on the 2nd day after surgery, sham-operated rats achieved an average score of 5.37 ± 0.23, SAH-induced rats scored 3.35 ± 0.67, and SAH-induced U0126-treated rats scored 5.00 ± 0.4. CONCLUSIONS The authors demonstrated that experimental SAH induces upregulation of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles and that treatment with the MEK1/2 inhibitor U0126 abolishes this receptor upregulation. They also demonstrated that experimental SAH results in sensorimotor deficits as assessed by a rotating pole test. These deficits were alleviated by U0126 treatment, suggesting that cerebrovascular receptor upregulation is critical for the functional outcome of delayed cerebral ischemia. The authors suggest that inhibition of MEK1/2 may be a promising new SAH treatment strategy.
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Ansar S, Larsen C, Maddahi A, Edvinsson L. Subarachnoid hemorrhage induces enhanced expression of thromboxane A2 receptors in rat cerebral arteries. Brain Res 2009; 1316:163-72. [PMID: 20026315 DOI: 10.1016/j.brainres.2009.12.031] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 12/08/2009] [Accepted: 12/12/2009] [Indexed: 10/20/2022]
Abstract
Cerebral ischemia remains the key cause of morbidity and mortality after subarachnoid hemorrhage (SAH) with a pathogenesis that is still poorly understood. The aim of the present study was to examine the involvement of thromboxane A(2) receptors (TP) in the pathophysiology of cerebral ischemia after SAH in cerebral arteries. SAH was induced in rats by injecting 250 microl of blood into the prechiasmatic cistern. Two days after the SAH, cerebral arteries were harvested and contractile responses to the TP receptor agonist U46619 were investigated with myographs. In addition, the contractile responses were examined after pretreatment with selective TP receptor antagonist GR3219b. The TP receptor RNA and protein levels were analyzed by quantitative real-time PCR and immunohistochemistry, respectively. The global and regional cerebral blood flows (CBFs) were quantified with an autoradiographic technique. SAH resulted in enhanced contractile responses to U46619 as compared to sham. The TP receptor antagonist GR3219b abolished the enhanced contractile responses to U46619 observed after SAH. The TP receptor mRNA level was elevated after SAH as compared to sham. The level of TP receptor protein on the smooth muscle cells (SMCs) was increased in SAH compared to sham. Global and regional CBFs were reduced in SAH as compared to sham. The results demonstrate that SAH results in CBF reduction and this is associated with the enhanced expression of TP receptors in the SMC of cerebral arteries and microvessels.
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Affiliation(s)
- Saema Ansar
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University, Sweden.
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