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Eftekhari S, Westgate CSJ, Uldall MS, Jensen RH. Preclinical update on regulation of intracranial pressure in relation to idiopathic intracranial hypertension. Fluids Barriers CNS 2019; 16:35. [PMID: 31767019 PMCID: PMC6878629 DOI: 10.1186/s12987-019-0155-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 11/13/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Elevated intracranial pressure (ICP) is observed in association with a range of brain disorders. One of these challenging disorders is idiopathic intracranial hypertension (IIH), characterized by raised ICP of unknown cause with significant morbidity and limited therapeutic options. In this review, special focus is put on the preclinical research performed in order to understand the pathophysiology behind ICP regulation and IIH. This includes cerebrospinal fluid dynamics, molecular mechanisms underlying disturbances in brain fluids leading to elevated ICP, role of obesity in IIH, development of an IIH model and ICP measurements in rodents. The review also discusses existing and new drug targets for IIH that have been evaluated in vivo. CONCLUSIONS ICP monitoring in rodents is challenging and different methods have been applied. Some of these methods are invasive, depend on use of anesthesia and only allow short-term monitoring. Long-term ICP recordings are needed to study IIH but existing methods are hampered by several limitations. As obesity is one of the most common risk factors for IIH, a rodent obese model has been developed that mimics some key aspects of IIH. The most commonly used drugs for IIH have been evaluated in vivo for their efficacy at lowering ICP in the existing animal models. These studies suggest these drugs, including acetazolamide, might have limited or no reducing effect on ICP. Two drug targets that can impact ICP in healthy rodents are topiramate and a glucagon-like peptide-1 receptor (GLP-1R) agonist. However, it remains to evaluate their effect in an IIH model with more precise and valid ICP monitoring system. Therefore, continued evaluation in the preclinical research with refined tools is of great importance to further understand the pathophysiology behind disorders with raised ICP and to explore new drug targets.
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Affiliation(s)
- Sajedeh Eftekhari
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Connar Stanley James Westgate
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Maria Schmidt Uldall
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
| | - Rigmor Hoejland Jensen
- Danish Headache Center, Department of Neurology, Glostrup Research Institute, Rigshospitalet-Glostrup, University of Copenhagen, Nordstjernevej 42, 2600 Glostrup, Denmark
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Bloygrund H, Franjy-Tal Y, Rosenzweig T, Abookasis D. Multiparameter wide-field integrated optical imaging system-based spatially modulated illumination and laser speckles in model of tissue injuries. JOURNAL OF BIOPHOTONICS 2019; 12:e201900141. [PMID: 31187933 DOI: 10.1002/jbio.201900141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 06/03/2019] [Accepted: 06/07/2019] [Indexed: 06/09/2023]
Abstract
In this report, an integrated optical platform based on spatial illumination together with laser speckle contrast technique was utilized to measure multiple parameters in live tissue including absorption, scattering, saturation, composition, metabolism, and blood flow. Measurements in three models of tissue injury including drug toxicity, artery occlusion, and acute hyperglycemia were used to test the efficacy of this system. With this hybrid apparatus, a series of structured light patterns at low and high spatial frequencies are projected onto the tissue surface and diffuse reflected light is captured by a CCD camera. A six position filter wheel, equipped with four bandpass filters centered at wavelengths of 650, 690, 800 and 880 nm is placed in front of the camera. Then, light patterns are blocked and a laser source at 650 nm illuminates the tissue while the diffusely reflected light is captured by the camera through the two remaining open holes in the wheel. In this manner, near-infrared (NIR) and laser speckle images are captured and stored together in the computer for off-line processing to reconstruct the tissue's properties. Spatial patterns are used to differentiate the effects of tissue scattering from those of absorption, allowing accurate quantification of tissue hemodynamics and morphology, while a coherent light source is used to study blood flow changes, a feature which cannot be measured with the NIR structured light. This combined configuration utilizes the strengths of each system in a complementary way, thus collecting a larger range of sample properties. In addition, once the flow and hemodynamics are measured, tissue oxygen metabolism can be calculated, a property which cannot be measured independently. Therefore, this merged platform can be considered a multiparameter wide-field imaging and spectroscopy modality. Overall, experiments demonstrate the capability of this spatially coregistered imaging setup to provide complementary, useful information of various tissue metrics in a simple and noncontact manner, making it attractive for use in a variety of biomedical applications.
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Affiliation(s)
- Hadas Bloygrund
- Department of Electrical and Electronics Engineering, Ariel University, Ariel, Israel
| | - Yarden Franjy-Tal
- Department of Electrical and Electronics Engineering, Ariel University, Ariel, Israel
| | - Tovit Rosenzweig
- Department of Molecular Biology and Nutritional Studies, Ariel University, Ariel, Israel
| | - David Abookasis
- Department of Electrical and Electronics Engineering, Ariel University, Ariel, Israel
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Reduced expression of IA channels is associated with post-ischemic seizures. Epilepsy Res 2016; 124:40-8. [PMID: 27259067 DOI: 10.1016/j.eplepsyres.2016.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 12/09/2015] [Accepted: 05/17/2016] [Indexed: 01/04/2023]
Abstract
PURPOSE Post-stroke seizures are considered as a major cause of epilepsy in adults. The pathophysiologic mechanisms resulting in post-stroke seizures are not fully understood. The present study attempted to reveal a new mechanism underlying neuronal hyperexcitability responsible to the seizure development after ischemic stroke. METHODS Transient global ischemia was produced in adult Wistar rats using the 4-vessel occlusion (4-VO) method. The spontaneous behavioral seizures were defined by the Racine scale III-V. The neuronal death in the brain was determined by hematoxylin-eosin staining. The expression levels of A-type potassium channels were analyzed by immunohistochemical staining and western blotting. RESULTS We found that the incidence of spontaneous behavioral seizures increased according to the severity of ischemia with 0% after 15-min ischemia and ∼50% after 25-min ischemia. All behavioral seizures occurred with 48h after ischemia. Morphological analysis indicated that brain damage was not correlated with behavioral seizures. Immunohistochemical staining showed that the expression levels of the A-type potassium channel subunit Kv4.2 was significantly reduced in ischemic brains with behavioral seizures, but not in ischemic brains without seizures. In addition, rats failing to develop spontaneous behavioral seizures within 2days after ischemia were more sensitive to bicuculline-induced seizures at 2 months after ischemia than control rats. Meanwhile, Kv4.2 expression was decreased in brain at 2 months after ischemia. CONCLUSION Our results demonstrated the reduction of Kv4.2 expression might contribute to the development of post-ischemic seizures and long-term increased seizure susceptibility after ischemia. The mechanisms underlying post-stroke seizures and epilepsy is unknown so far. The down-regulation of IA channels may explained the abnormal neuronal hyperexcitability responsible for the seizure development after ischemic stroke.
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Liang Y, Lei Z, Zhang H, Xu Z, Cui Q, Xu ZC. Toll-like receptor 4 is associated with seizures following ischemia with hyperglycemia. Brain Res 2014; 1590:75-84. [DOI: 10.1016/j.brainres.2014.09.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 09/06/2014] [Indexed: 12/26/2022]
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Lei Z, Zhang H, Liang Y, Cui Q, Xu Z, Xu ZC. Reduced expression of IA channels is associated with postischemic seizures in hyperglycemic rats. J Neurosci Res 2014; 92:1775-84. [PMID: 25043828 DOI: 10.1002/jnr.23445] [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: 02/20/2014] [Revised: 04/14/2014] [Accepted: 06/01/2014] [Indexed: 01/04/2023]
Abstract
Poststroke seizures are considered to be the major cause of epilepsy in the elderly. The mechanisms of poststroke seizures remain unclear. A history of diabetes mellitus has been identified as an independent predictor of acute poststroke seizures in stroke patients. The present study sought to reveal the mechanisms for the development of postischemic seizures under hyperglycemic conditions. Transient forebrain ischemia was produced in adult Wistar rats by using the four-vessel occlusion method. At the normal blood glucose level, seizures occurred in ∼50% of rats after 25 min of ischemia. However, in rats with hyperglycemia, the incidence rate of postischemic seizures was significantly increased to 100%. The occurrence of postischemic seizures was not correlated with the severity of brain damage in hyperglycemic rats. Mannitol, an osmotic diuretic agent, could neither prevent postischemic seizures nor alleviate the exacerbated brain damage in the presence of hyperglycemia. K(+) channels play a critical role in controlling neuronal excitability. The expression of A-type K(+) channel subunit Kv4.2 in the hippocampus and the cortex was significantly reduced in hyperglycemic rats with seizures compared with those without seizures. These results suggest that the reduction of Kv4.2 expression could contribute to the development of postischemic seizures in hyperglycemia.
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Affiliation(s)
- Zhigang Lei
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
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Uldall M, Juhler M, Skjolding AD, Kruuse C, Jansen-Olesen I, Jensen R. A novel method for long-term monitoring of intracranial pressure in rats. J Neurosci Methods 2014; 227:1-9. [PMID: 24521617 DOI: 10.1016/j.jneumeth.2014.01.036] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/30/2014] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND In preclinical neurological studies, monitoring intracranial pressure (ICP) in animal models especially in rodents is challenging. Further, the lack of methods for long-term ICP monitoring has limited the possibilities to conduct prolonged studies on ICP fluctuations in parallel to disease progression or therapeutic interventions. For these reasons we aimed to set up a simple and valid method for long-term ICP recordings in rats. NEW METHOD A novel ICP method employing epidural probes was developed and validated by simultaneously ICP recordings in the lateral ventricle and in the epidural space. The two pressures were recorded twice a week for 59 days and the correlation was studied. RESULTS The two pressure recordings correlated exceptionally well and the R(2) values on each recording day ranged between 0.99 and 1.00. However, the ventricular probes caused a number of complications including loss of patency and tissue damage probably due to cerebral infection, whereas the epidural probes were safe and reliable throughout the entire study. COMPARISON WITH EXISTING METHODS Epidural probes are much easier to implant than ventricular probes. In addition, these new probes are far less invasive and induce no apparent mechanical tissue damage and highly decrease the infection risk associated with ICP recordings. CONCLUSION Epidural ICP recorded with this new method is identical to the ventricular ICP for at least 59 days but is far less complicated and safer for the animals. The long-term method described is reliable, valid, inexpensive, and may be used in multiple disease models to study ICP.
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Affiliation(s)
- Maria Uldall
- Danish Headache Center, Building 24, Department of Neurology, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark; Research Institute, Danish Headache Center, Glostrup, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark
| | - Marianne Juhler
- Department of Neurosurgery, The National Hospital, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - Anders Daehli Skjolding
- Department of Neurosurgery, The National Hospital, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen Ø, Denmark
| | - Christina Kruuse
- Research Institute, Danish Headache Center, Glostrup, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark; Department of Neurology, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, 2730 Herlev, Denmark
| | - Inger Jansen-Olesen
- Danish Headache Center, Building 24, Department of Neurology, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark; Research Institute, Danish Headache Center, Glostrup, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark
| | - Rigmor Jensen
- Danish Headache Center, Building 24, Department of Neurology, Glostrup Hospital, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark.
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Low-dose but not high-dose prostaglandin E1 improves the histological outcome of severe forebrain ischemia in rats. J Anesth 2010; 24:234-9. [DOI: 10.1007/s00540-010-0876-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 11/25/2009] [Indexed: 11/30/2022]
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A tension pneumocephalus caused by severe traumatic brain injury. World J Pediatr 2009; 5:74, author reply 74. [PMID: 19172340 DOI: 10.1007/s12519-009-0016-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Salci K, Enblad P, Piper I, Contant C, Nilsson P. A model for studies of intracranial volume pressure dynamics in traumatic brain injury. J Neurotrauma 2004; 21:317-27. [PMID: 15115606 DOI: 10.1089/089771504322972103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The present study was undertaken to establish an experimental trauma model where it was possible to alter intracranial pressure (ICP) dynamics without raising intracranial pressure to abnormal levels and monitor metabolic disturbances with microdialysis. Thirty rats were intubated and mechanically ventilated before and after trauma. ICP was measured in the left ventricle. A weight-drop technique (21 g from 35 cm) with a brain compression of 1.5 mm was used to produce the injury. Intracranial compensatory volume was decreased 20 or 60 microL by placement of rubber film between the dura mater and bone. A bolus injection technique was used for the pressure volume response. ICP remained within normal limits for 2 h after trauma irrespective of the reduction in compensatory intracranial volume. Pressure-volume index decreased from 0.0825 +/- 0.009 to 0.0779 +/- 0.011 mL in the sham trauma and from 0.0871 +/- 0.018 to 0.0748 +/- 0.017 mL in the trauma groups (p < 0.015) when the intracranial volume was reduced by 60 microL. Intracranial compliance was not affected significantly. The present study shows that it is possible to vary ICP dynamics in a traumatic brain injury model without causing pathological increases in baseline ICP. This model may be used to study the effects of secondary insults (i.e., hypotension, hypoxia, hypercarbia, and hyperthermia) on the injured brain when ICP is normal but intracranial compensatory volume is impaired.
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Affiliation(s)
- K Salci
- Department of Neurosurgery, Uppsala University Hospital, Uppsala, Sweden
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Hauck EF, Apostel S, Hoffmann JF, Heimann A, Kempski O. Capillary flow and diameter changes during reperfusion after global cerebral ischemia studied by intravital video microscopy. J Cereb Blood Flow Metab 2004; 24:383-91. [PMID: 15087707 DOI: 10.1097/00004647-200404000-00003] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The reaction of cerebral capillaries to ischemia is unclear. Based on Hossmann's observation of postischemic "delayed hypoperfusion," we hypothesized that capillary flow is decreased during reperfusion because of increased precapillary flow resistance. To test this hypothesis, we measured cerebral capillary erythrocyte velocity and diameter changes by intravital microscopy in gerbils. A cranial window was prepared over the frontoparietal cortex in 26 gerbils anesthetized with halothane. The animals underwent either a sham operation or fifteen minutes of bilateral carotid artery occlusion causing global cerebral ischemia. Capillary flow velocities were measured by frame-to-frame tracking of fluorescein isothiocyanate labeled erythrocytes in 1800 capillaries after 1-hour reperfusion. Capillary flow velocities were decreased compared to control (0.25 +/- 0.27 mm/s vs. 0.76 +/- 0.45 mm/s; P<0.001). Precapillary arteriole diameters in reperfused animals were reduced to 76.3 +/- 6.9% compared to baseline (P<0.05). Capillary diameters in reperfused animals (2.87 +/- 0.97 microm) were reduced (P<0.001) compared to control (4.08 +/- 1.19 microm). Similar reductions of precapillary (24%) and capillary vessel diameters (30%) and absolute capillary flow heterogeneity indicate that delayed (capillary) hypoperfusion occurs as a consequence of increased precapillary arteriole tone during reperfusion.
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Affiliation(s)
- Erik F Hauck
- Divison of Neurosurgery, University of Texas Medical Branch, Galveston, USA
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Morimoto Y, Morimoto Y, Kemmotsu O, Alojado ES. Extracellular acidosis delays cell death against glucose-oxygen deprivation in neuroblastoma x glioma hybrid cells. Crit Care Med 1997; 25:841-7. [PMID: 9187605 DOI: 10.1097/00003246-199705000-00021] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE To determine whether extracellular acidosis delays cell death against glucose-oxygen deprivation and, if so, whether this result is due to inhibition of calcium (Ca2+) influx or preservation of cellular energy state. DESIGN Randomized, controlled, prospective study. SETTING University research laboratory. SUBJECTS Differentiated neuroblastoma x glioma NG108-15 cells. INTERVENTIONS Experiment 1: cells were incubated for 8 hrs in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid-buffered medium under glucose-oxygen deprivation at pH 7.4, 6.8, 6.5, 6.2, 5.6, or 5.0. Experiment 2: cells were incubated for 8 hrs under glucose-oxygen deprivation after excluding extracellular calcium from culture medium at pH 7.4 or 6.2. Experiment 3: cells were incubated for 2, 4, 6, or 8 hrs in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid-buffered medium under glucose-oxygen deprivation at pH 7.4 or 6.2 and assayed for high-energy phosphates. MEASUREMENTS AND MAIN RESULTS Cell viability was measured with flow cytometry after the cells were stained with fluorescein diacetate and propidium iodide. Cellular adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate were analyzed with high-performance liquid chromatography. Cell viability was significantly greater at pH 6.2 than at pH 7.4 in experiment 1. By excluding extracellular calcium, a significant difference in viability between pH 7.4 and 6.2 persisted in experiment 2. Energy charge and the concentration of adenosine triphosphate were significantly greater at pH 6.2 than at pH 7.4 in the intervals preceding manifestation of a differential effect of acidosis on cell viability in experiment 3. CONCLUSIONS Extracellular acidosis at pH 6.2 delayed cell death against glucose-oxygen deprivation. This protective effect by extracellular acidosis may be due to preservation of the cellular energy state in NG108-15 cells, although this study does not exclude the possibility that in other cell types, inhibition of calcium influx may have an effect.
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Affiliation(s)
- Y Morimoto
- Department of Anesthesiology and Intensive Care, Hokkaido University School of Medicine, Sapporo, Japan
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