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Bens N, Kulkarni P, Ferris CF. Changes in cerebral vascular reactivity following mild repetitive head injury in awake rats: modeling the human experience. Exp Brain Res 2024; 242:2433-2442. [PMID: 39162729 PMCID: PMC11422282 DOI: 10.1007/s00221-024-06907-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 08/01/2024] [Indexed: 08/21/2024]
Abstract
The changes in brain function in response to mild head injury are usually subtle and go undetected. Physiological biomarkers would aid in the early diagnosis of mild head injury. In this study we used hypercapnia to follow changes in cerebral vascular reactivity after repetitive mild head injury. We hypothesized head injury would reduce vascular reactivity. Rats were maintained on a reverse light-dark cycle and head impacted daily at 24 h intervals over three days. All head impacts were delivered while rats were fully awake under red light illumination. There was no neuroradiological evidence of brain damage. After the 3rd impact rats were exposed to 5% CO2 and imaged for changes in BOLD signal. All imaging was done while rats were awake without the confound of anesthesia. The data were registered to a 3D MRI rat atlas with 171 segmented brain areas providing site specific information on vascular reactivity. The changes in vascular reactivity were not uniform across the brain. The prefrontal cortex, somatosensory cortex and basal ganglia showed the hypothesized decrease in vascular reactivity while the cerebellum, thalamus, brainstem, and olfactory system showed an increase in BOLD signal to hypercapnia.
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Affiliation(s)
- Nicole Bens
- Center for Translational Neuroimaging, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Praveen Kulkarni
- Center for Translational Neuroimaging, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA
| | - Craig F Ferris
- Center for Translational Neuroimaging, Northeastern University, 360 Huntington Ave, Boston, MA, 02115, USA.
- Departments of Psychology and Pharmaceutical Sciences, Northeastern University, Boston, MA, USA.
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2
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Li Z, Gong P, Zhang M, Li C, Xiao P, Yu M, Wang X, An L, Bi F, Song X, Wang X. Multi-parametric MRI assessment of melatonin regulating the polarization of microglia in rats after cerebral ischemia/reperfusion injury. Brain Res Bull 2023; 204:110807. [PMID: 37923146 DOI: 10.1016/j.brainresbull.2023.110807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 10/15/2023] [Accepted: 10/31/2023] [Indexed: 11/07/2023]
Abstract
OBJECTIVES Multi-parametric magnetic resonance imaging (MRI) can provide comprehensive and valuable information for precise diagnosis and treatment evaluation of a number of diseases. In this study, the neuroprotective effects of melatonin (Mel) on a rat model of cerebral ischemia/reperfusion injury (CIRI) were assessed by multi-parametric MRI combined with histopathological techniques for longitudinal monitoring of the lesion microenvironment. METHODS Sixty Sprague Dawley (SD) rats were randomly divided into three groups: the Sham, CIRI and CIRI + Mel groups. At multiple time points after ischemia, MRI scanning was performed on a 7.0 Tesla MRI scanner. Multi-parametric MRI includes T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), and chemical exchange saturation transfer (CEST)-MRI. CEST effects were calculated by the Lorentzian difference method, 3.5 ppm indicates amide protons of mobile proteins/peptide (Amide-CEST) and 2.0 ppm indicates amine protons (Guan-CEST). Multiple histopathological techniques were used to examine the histopathological changes and explore the therapeutic effects of Mel. RESULTS T2WI and DWI-MRI could localize the infarct foci and areas in CIRI rats, which was further validated by staining, 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining, hematoxylin and eosin (H&E) staining, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labelling (TUNEL) staining. After Mel treatment, T2WI and DWI-MRI showed smaller infarct volume, and neurons displayed improved morphology with less apoptosis rates. Notably, Amide-CEST and Guan-CEST signal decreased as early as 2 h after CIRI (all P <0.001), reflecting the change of pH after ischemia. After Mel treatment, both Amide-CEST and Guan-CEST signal increased in ischemic cortex and striatum compared with control group (all P < 0.001). The immunofluorescence staining and western blotting analysis suggested the expression of M2 microglia increased after Mel treatment; While,after Mel treatment the inflammatory factor interleukin-1β (IL-1β) decreased compared with control CIRI rats. CONCLUSIONS Multi-parametric MRI was shown to be an effective method to monitor the brain damage in a rat model of CIRI and assess the therapeutic effects of Mel treatment. Amide-CEST and Guan-CEST were especially sensitive to the changes in brain microenvironment during the early stage after CIRI. Furthermore, the neuroprotective effect of Mel treatment is associated with its promotion of the microglia polarized to M2 type in CIRI rats.
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Affiliation(s)
- Zhen Li
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China; Medical Imaging Center, Affiliated Hospital of Weifang Medical University, Weifang 261031, Shandong Province, China
| | - Ping Gong
- Medical Imaging Center, Affiliated Hospital of Weifang Medical University, Weifang 261031, Shandong Province, China
| | - Mengbei Zhang
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China; Department of Radiology, Zibo Central Hospital, Zibo 255020, Shandong Province, China
| | - Chen Li
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China
| | - Peilun Xiao
- Department of Anatomy, School of Basic Medicine, Weifang Medical University, Weifang 261053, Shandong Province, China
| | - Miao Yu
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China
| | - Xizhen Wang
- Medical Imaging Center, Affiliated Hospital of Weifang Medical University, Weifang 261031, Shandong Province, China
| | - Lin An
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China
| | - Fangfang Bi
- Department of Neurology, The Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai 519000, Guangdong Province, China.
| | - Xiaolei Song
- Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing 100084, China.
| | - Xiaoli Wang
- School of Medical Imaging, Weifang Medical University, Weifang 261053, Shandong Province, China; Medical Imaging Center, Affiliated Hospital of Weifang Medical University, Weifang 261031, Shandong Province, China.
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3
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Huang J, Zhang Y, Zhang Q, Wei L, Zhang X, Jin C, Yang J, Li Z, Liang S. The current status and trend of the functional magnetic resonance combined with stimulation in animals. Front Neurosci 2022; 16:963175. [PMID: 36213733 PMCID: PMC9540855 DOI: 10.3389/fnins.2022.963175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/05/2022] [Indexed: 11/16/2022] Open
Abstract
As a non-radiative, non-invasive imaging technique, functional magnetic resonance imaging (fMRI) has excellent effects on studying the activation of blood oxygen levels and functional connectivity of the brain in human and animal models. Compared with resting-state fMRI, fMRI combined with stimulation could be used to assess the activation of specific brain regions and the connectivity of specific pathways and achieve better signal capture with a clear purpose and more significant results. Various fMRI methods and specific stimulation paradigms have been proposed to investigate brain activation in a specific state, such as electrical, mechanical, visual, olfactory, and direct brain stimulation. In this review, the studies on animal brain activation using fMRI combined with different stimulation methods were retrieved. The instruments, experimental parameters, anesthesia, and animal models in different stimulation conditions were summarized. The findings would provide a reference for studies on estimating specific brain activation using fMRI combined with stimulation.
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Huang S, Shen Q, Watts LT, Long JA, O'Boyle M, Nguyen T, Muir E, Duong TQ. Resting-State Functional Magnetic Resonance Imaging of Interhemispheric Functional Connectivity in Experimental Traumatic Brain Injury. Neurotrauma Rep 2021; 2:526-540. [PMID: 34901946 PMCID: PMC8655818 DOI: 10.1089/neur.2021.0023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although resting-state functional magnetic resonance imaging (rsfMRI) has the potential to offer insights into changes in functional connectivity networks after traumatic brain injury (TBI), there are few studies that examine the effects of moderate TBI for monitoring functional recovery in experimental TBI, and thus the neural correlates of brain recovery from moderate TBI remain incompletely understood. Non-invasive rsfMRI was used to longitudinally investigate changes in interhemispheric functional connectivity (IFC) after a moderate TBI to the unilateral sensorimotor cortex in rats (n = 9) up to 14 days. Independent component analysis of the rsfMRI data was performed. Correlations of rsfMRI sensorimotor networks were made with changes in behavioral scores, lesion volume, and T2- and diffusion-weighted images across time. TBI animals showed less localized rsfMRI patterns in the sensorimotor network compared to sham (n = 6) and normal (n = 5) animals. rsfMRI clusters in the sensorimotor network showed less bilateral symmetry compared to sham and normal animals, indicative of IFC disruption. With time after injury, many of the rsfMRI patterns in the sensorimotor network showed more bilateral symmetry, indicative of IFC recovery. The disrupted IFC in the sensorimotor and subsequent partial recovery showed a positive correlation with changes in behavioral scores. Overall, rsfMRI detected widespread disruption and subsequent recovery of IFC within the sensorimotor networks post-TBI, which correlated with behavioral changes. Therefore, rsfMRI offers the means to probe functional brain reorganization and thus has the potential to serve as an imaging marker to longitudinally stage TBI and monitor for novel treatments.
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Affiliation(s)
- Shiliang Huang
- Research Imaging Institute, UT Health San Antonio, San Antonio, Texas, USA
| | - Qiang Shen
- Research Imaging Institute, UT Health San Antonio, San Antonio, Texas, USA.,Department of Radiology, UT Health San Antonio, San Antonio, Texas, USA
| | - Lora Talley Watts
- Department of Clinical and Applied Science Education, University of the Incarnate Word School of Osteopathic Medicine, San Antonio, Texas, USA
| | - Justin A Long
- Research Imaging Institute, UT Health San Antonio, San Antonio, Texas, USA
| | - Michael O'Boyle
- Research Imaging Institute, UT Health San Antonio, San Antonio, Texas, USA
| | - Tony Nguyen
- Department of Radiology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York, New York, USA
| | - Eric Muir
- Department of Radiology, Stony Brook Medicine, Stony Brook, New York, USA
| | - Timothy Q Duong
- Department of Radiology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York, New York, USA
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Li Y, Li R, Liu M, Nie Z, Muir ER, Duong TQ. MRI study of cerebral blood flow, vascular reactivity, and vascular coupling in systemic hypertension. Brain Res 2020; 1753:147224. [PMID: 33358732 DOI: 10.1016/j.brainres.2020.147224] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/30/2020] [Accepted: 11/27/2020] [Indexed: 01/14/2023]
Abstract
Chronic hypertension alters cerebrovascular function, which can lead to neurovascular pathologies and increased susceptibility to neurological disorders. The purpose of this study was to utilize in vivo MRI methods with corroborating immunohistology to evaluate neurovascular dysfunction due to progressive chronic hypertension. The spontaneously hypertensive rat (SHR) model at different stages of hypertension was studied to evaluate: i) basal cerebral blood flow (CBF), ii) cerebrovascular reactivity (CVR) assessed by CBF and blood-oxygenation level dependent (BOLD) signal changes to hypercapnia, iii) neurovascular coupling from CBF and BOLD changes to forepaw stimulation, and iv) damage of neurovascular unit (NVU) components (microvascular, astrocyte and neuron densities). Comparisons were made with age-matched normotensive Wistar Kyoto (WKY) rats. In 10-week SHR (mild hypertension), basal CBF was higher (p < 0.05), CVR trended higher, and neurovascular coupling response was higher (p < 0.05), compared to normotensive rats. In 40-week SHR (severe hypertension), basal CBF, CVR, and neurovascular coupling response were reversed to similar or below normotensive rats, and were significantly different from 10-week SHR (p < 0.05). Immunohistological analysis found significantly reduced microvascular density, increased astrocytes, and reduced neuronal density in SHR at 40 weeks (p < 0.05) but not at 10 weeks (p > 0.05) in comparison to age-matched controls. In conclusion, we observed a bi-phasic basal CBF, CVR and neurovascular coupling response from early to late hypertension using in vivo MRI, with significant changes prior to changes in the NVU components from histology. MRI provides clinically relevant data that might be useful to characterize neurovascular pathogenesis on the brain in hypertension.
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Affiliation(s)
- Yunxia Li
- Department of Neurology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Renren Li
- Department of Neurology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Meng Liu
- Department of Neurology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Zhiyu Nie
- Department of Neurology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China.
| | - Eric R Muir
- Department of Radiology, Renaissance School of Medicine, Stony Brook University Hospital, Stony Brook, NY, USA
| | - Tim Q Duong
- Department of Radiology, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, USA.
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Mechanism of salvianolic acid B neuroprotection against ischemia/reperfusion induced cerebral injury. Brain Res 2018; 1679:125-133. [DOI: 10.1016/j.brainres.2017.11.027] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 11/07/2017] [Accepted: 11/24/2017] [Indexed: 01/06/2023]
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Chen J, Yang Y, Shen L, Ding W, Chen X, Wu E, Cai K, Wang G. Hypoxic Preconditioning Augments the Therapeutic Efficacy of Bone Marrow Stromal Cells in a Rat Ischemic Stroke Model. Cell Mol Neurobiol 2017; 37:1115-1129. [PMID: 27858286 DOI: 10.1007/s10571-016-0445-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 11/10/2016] [Indexed: 12/19/2022]
Abstract
Transplantation of bone marrow stromal cells (BMSCs) is a promising therapy for ischemic stroke, but the poor oxygen environment in brain lesions limits the efficacy of cell-based therapies. Here, we tested whether hypoxic preconditioning (HP) could augment the efficacy of BMSC transplantation in a rat ischemic stroke model and investigated the underlying mechanism of the effect of HP. In vitro, BMSCs were divided into five passage (P0, P1, P2, P3, and P4) groups, and HP was applied to the groups by incubating the cells with 1% oxygen for 0, 4, 8, 12, and 24 h, respectively. We demonstrated that the expression of hypoxia-inducible factor-1α (HIF-1α) was increased in the HP-treated BMSCs, while their viability was unchanged. We also found that HP decreased the apoptosis of BMSCs during subsequent simulated ischemia-reperfusion (I/R) injury, especially in the 8-h HP group. In vivo, a rat transient focal cerebral ischemia model was established. These rats were administered normal cultured BMSCs (N-BMSCs), HP-treated BMSCs (H-BMSCs), or DMEM cell culture medium (control) at 24 h after the ischemic insult. Compared with the DMEM control group, the two BMSC-transplanted groups exhibited significantly improved functional recovery and reduced infarct volume, especially the H-BMSC group. Moreover, HP decreased neuronal apoptosis and enhanced the expression of BDNF and VEGF in the ischemic brain. Survival and differentiation of transplanted BMSCs were also increased by HP, and the quantity of engrafted BMSCs was significantly correlated with neurological function improvement. These results suggest that HP may enhance the therapeutic efficacy of BMSCs in an ischemic stroke model. The underlying mechanism likely involves the inhibition of caspase-3 activation and an increasing expression of HIF-1α, which promotes angiogenesis and neurogenesis and thereby reduces neuronal death and improves neurological function.
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Affiliation(s)
- Jin Chen
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China
| | - Yuanyuan Yang
- Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
| | - Lihua Shen
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China.
| | - Wensen Ding
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China
| | - Xiang Chen
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China
| | - Erbing Wu
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China
| | - Kefu Cai
- Department of Neurology, Affiliated Hospital of Nantong University, 20 XiSi Road, Nantong, 226001, China
| | - Guohua Wang
- Department of Neuropharmacology, Institute of Nautical Medicine, Nantong University, 9 Seyuan Road, Nantong, 226019, Jiangsu, China.
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
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Rodriguez P, Zhao J, Milman B, Tiwari YV, Duong TQ. Methylene blue and normobaric hyperoxia combination therapy in experimental ischemic stroke. Brain Behav 2016; 6:e00478. [PMID: 27458543 PMCID: PMC4951618 DOI: 10.1002/brb3.478] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 03/11/2016] [Accepted: 03/18/2016] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION Ischemic stroke is a global burden that contributes to the disability and mortality of millions of patients. This study aimed to evaluate the efficacy of combined MB (methylene blue) and NBO (normobaric hyperoxia) therapy in experimental ischemic stroke. METHODS Rats with transient (60 min) MCAO (middle cerebral artery occlusion) were treated with: (1) air + vehicle (N = 8), (2) air + MB (N = 8), (3) NBO + vehicle (N = 7), and (4) NBO + MB (N = 9). MB (1 mg/kg) was administered at 30 min, again on days 2, 7, and 14 after stroke. NBO was given during MRI (30-150 min) on day 0, and again 1 h each during MRI on subsequent days. Serial diffusion, perfusion and T2 MRI were performed to evaluate lesion volumes. Foot-fault and cylinder tests were performed to evaluate sensorimotor function. RESULTS The major findings were: (1) NBO + MB therapy showed a greater decrease in infarct volume compared to NBO alone, but similar infarct volume compared to MB alone, (2) NBO + MB therapy accelerated sensorimotor functional recovery compared to NBO or MB alone, (3) Infarct volumes on day 2 did not change significantly from those on day 28 for all four groups, but behavioral function continued to show improved recovery in the NBO + MB group. CONCLUSIONS These findings support the hypothesis that combined NBO + MB further improves functional outcome and reduces infarct volume compared to either treatment alone and these improvements extended up to 28 days.
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Affiliation(s)
- Pavel Rodriguez
- Research Imaging InstituteUniversity of Texas Health Science CenterSan AntonioTexas
- Department of RadiologyUniversity of Texas Health Science CenterSan AntonioTexas
| | - Jiang Zhao
- Research Imaging InstituteUniversity of Texas Health Science CenterSan AntonioTexas
- Department of Anatomy and EmbryologyPeking University Health Science CenterBeijingChina
| | - Brian Milman
- Research Imaging InstituteUniversity of Texas Health Science CenterSan AntonioTexas
| | - Yash Vardhan Tiwari
- Research Imaging InstituteUniversity of Texas Health Science CenterSan AntonioTexas
- Department of Biomedical EngineeringUniversity of TexasSan AntonioTexas
| | - Timothy Q. Duong
- Research Imaging InstituteUniversity of Texas Health Science CenterSan AntonioTexas
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9
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Tiwari YV, Jiang Z, Sun Y, Du F, Rodriguez P, Shen Q, Duong TQ. Effects of stroke severity and treatment duration in normobaric hyperoxia treatment of ischemic stroke. Brain Res 2016; 1635:121-9. [PMID: 26826010 PMCID: PMC4779399 DOI: 10.1016/j.brainres.2016.01.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Revised: 01/15/2016] [Accepted: 01/19/2016] [Indexed: 11/26/2022]
Abstract
In order to improve clinical trial design and translation of normobaric oxygen (NBO) treatment of ischemic stroke, NBO treatment parameters need to be better understood. This study investigated NBO treatment efficacy at two different stroke severities and two NBO treatment durations in rats. For the 60-min middle cerebral artery occlusion (MCAO), NBO treatment for 25 min and 150 min were studied. For the 90-min MCAO, NBO treatment for 55 min and 150 min were studied. Cerebral blood flow (CBF), apparent diffusion coefficients (ADC) and T2 MRI were acquired during occlusion prior to treatment, after reperfusion, and 48h after MCAO. The effects of NBO treatment on lesion volumes, and CBF, ADC and T2 of ischemic core, perfusion-diffusion mismatch and normal tissue were analyzed longitudinally. The major findings were: i) NBO treatment was effective in both groups of stroke severities, salvaging similar percentage of initial abnormal ADC tissue, and ii) NBO treatments continued after reperfusion were more beneficial than NBO treatment during occlusion alone for both MCAO groups. These findings underscore the importance of the effects of NBO duration and stroke severity on treatment outcomes.
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Affiliation(s)
- Yash Vardhan Tiwari
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA; Department of Biomedical Engineering, University of Texas, San Antonio, TX, USA
| | - Zhao Jiang
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
| | - Yuhao Sun
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
| | - Fang Du
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
| | - Pavel Rodriguez
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
| | - Qiang Shen
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX 78229, USA.
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Leithner C, Füchtemeier M, Jorks D, Mueller S, Dirnagl U, Royl G. Infarct Volume Prediction by Early Magnetic Resonance Imaging in a Murine Stroke Model Depends on Ischemia Duration and Time of Imaging. Stroke 2015; 46:3249-59. [PMID: 26451016 DOI: 10.1161/strokeaha.114.007832] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 09/02/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Despite standardization of experimental stroke models, final infarct sizes after middle cerebral artery occlusion (MCAO) vary considerably. This introduces uncertainties in the evaluation of drug effects on stroke. Magnetic resonance imaging may detect variability of surgically induced ischemia before treatment and thus improve treatment effect evaluation. METHODS MCAO of 45 and 90 minutes induced brain infarcts in 83 mice. During, and 3 and 6 hours after MCAO, we performed multiparametric magnetic resonance imaging. We evaluated time courses of cerebral blood flow, apparent diffusion coefficient (ADC), T1, T2, accuracy of infarct prediction strategies, and impact on statistical evaluation of experimental stroke studies. RESULTS ADC decreased during MCAO but recovered completely on reperfusion after 45 and partially after 90-minute MCAO, followed by a secondary decline. ADC lesion volumes during MCAO or at 6 hours after MCAO largely determined final infarct volumes for 90 but not for 45 minutes MCAO. The majority of chance findings of final infarct volume differences in random group allocations of animals were associated with significant differences in early ADC lesion volumes for 90, but not for 45-minute MCAO. CONCLUSIONS The prediction accuracy of early magnetic resonance imaging for infarct volumes depends on timing of magnetic resonance imaging and MCAO duration. Variability of the posterior communicating artery in C57Bl6 mice contributes to differences in prediction accuracy between short and long MCAO. Early ADC imaging may be used to reduce errors in the interpretation of post MCAO treatment effects on stroke volumes.
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Affiliation(s)
- Christoph Leithner
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.).
| | - Martina Füchtemeier
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.)
| | - Devi Jorks
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.)
| | - Susanne Mueller
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.)
| | - Ulrich Dirnagl
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.)
| | - Georg Royl
- From the Department of Experimental Neurology, Charité Universitätsmedizin, Berlin, Germany (C.L., M.F., D.J., S.M., U.D., G.R.); Center for Stroke Research Berlin, Berlin, Germany (C.L., D.J., S.M., U.D., G.R.); NeuroCure Cluster of Excellence, Berlin, Germany (C.L., U.D.); German Center for Neurodegenerative Diseases (DZNE) (M.F., U.D.) and German Center for Cardiovascular Diseases (DZHK) (U.D.), Berlin site, Charitéplatz, Berlin, Germany; and Department of Neurology, University of Lübeck, Lübeck, Germany (G.R.)
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YAN GEN, DAI ZHUOZHI, XUAN YINGHUA, WU RENHUA. Early metabolic changes following ischemia onset in rats: an in vivo diffusion-weighted imaging and 1H-magnetic resonance spectroscopy study at 7.0 T. Mol Med Rep 2015; 11:4109-14. [PMID: 25634261 PMCID: PMC4394971 DOI: 10.3892/mmr.2015.3283] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 01/02/2015] [Indexed: 02/05/2023] Open
Abstract
Despite improvements in imaging techniques, it remains challenging to quantitatively assess the time of ischemic onset of an acute ischemic stroke. It is crucial to evaluate the early signs of infarction, which are predictive of responses to recombinant tissue plasminogen activator within a treatment window of 4.5 h after stroke induction. The aim of the present study was to assess and quantify the onset time for hyperacute middle cerebral artery occlusion (MCAO) ischemic stroke by measuring the apparent diffusion coefficient (ADC) of diffusion‑weighted imaging (DWI) and 1H‑magnetic resonance spectroscopy (MRS) at 7.0 T. DWI, conventional T2‑weighted imaging (T2WI) and subsequent focal ADCs were employed to evaluate ischemic brain lesions in a rat model of MCAO (n=20) at different time‑points following a stroke. A quantitation of local changes in metabolite concentrations within the lesions was performed using MRS. Proton metabolites were quantified automatically using LCModel software. At 30 min after MCAO, intense signals were observed in the DWI spectra of all animals. No abnormal signal was observed within 3 h by T2WI. ADC images of the central area, peripheral striping and on the fringes of the infarction demonstrated a lower signal than that of the normal side. The ADC decreased significantly within 30 min after infarction, followed by a gradual elevation in volatility levels and then becoming relatively stable at a lower level 3 h later. MRS exhibited a consistent elevation of lactate and reduced N‑acetyl aspartic acid. Glutamate and taurine reached a maximum 2 h after MCAO and began to decrease 1 h later. In conclusion, the present study demonstrated that hyperacute ischemic stroke can be quantitatively detected with the application of ADC, DWI and MRS. These methods may also be used to quantitatively assess the ischemic onset time of a hyperacute stroke.
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Affiliation(s)
- GEN YAN
- Department of Radiology, Affiliated Hospital, Jiangnan University, Wuxi, Jiangsu 214062, P.R. China
- Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China
| | - ZHUOZHI DAI
- Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China
- Provincial Key Laboratory of Medical Molecular Imaging, Shantou, Guangdong 515041, P.R. China
| | - YINGHUA XUAN
- Department of Basic Medicine, Jiangnan University Medical School, Wuxi, Jiangsu 214122, P.R. China
| | - RENHUA WU
- Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, Shantou, Guangdong 515041, P.R. China
- Provincial Key Laboratory of Medical Molecular Imaging, Shantou, Guangdong 515041, P.R. China
- Correspondence to: Professor Renhua Wu, Department of Radiology, The Second Affiliated Hospital, Shantou University Medical College, 22 Dongxiabei Road, Shantou, Guangdong 515041, P.R. China, E-mail:
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Huang CH, Shih YYI, Siow TY, Hsu YH, Chen CCV, Lin TN, Jaw FS, Chang C. Temporal assessment of vascular reactivity and functionality using MRI during postischemic proangiogenenic vascular remodeling. Magn Reson Imaging 2015; 33:903-10. [PMID: 25944092 DOI: 10.1016/j.mri.2015.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 03/13/2015] [Accepted: 04/26/2015] [Indexed: 11/18/2022]
Abstract
Postischemic angiogenesis is an important recovery mechanism. Both arteries and veins are upregulated during angiogenesis, but eventually there are more angiogenic veins than arteries in terms of number and length. It is critical to understand how the veins are modulated after ischemia and then transitioned into angiogenic vessels during the proangiogenic stage to finally serve as a restorative strength to the injured area. Using a rat model of transient focal cerebral ischemia, the hypercapnic blood oxygen level-dependent (BOLD) response was used to evaluate vascular reactivity, while the hyperoxic BOLD and tissue oxygen level-dependent (TOLD) responses were used to evaluate the vascular functionality at 1, 3, and 7days after ischemia. Vessel-like venous signals appeared on R2* maps on days 3 and 7, but not on day 1. The large hypercapnic BOLD responses on days 3 and 7 indicated that these areas have high vascular reactivity. The temporal correlation between vascular reactivity and the immunoreactivity to desmin and VEGF further indicates that the integrity of vascular reactivity is associated with the pericyte coverage as regulated by the VEGF level. Vascular functionality remained low on days 1, 3, and 7, as reflected by the small hyperoxic BOLD and large hyperoxic TOLD responses, indicating the low oxygen consumption of the ischemic tissues. These functional changes in proangiogenic veins may be critical for angiogenesis.
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Affiliation(s)
- Chien-Hsiang Huang
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Yen-Yu Ian Shih
- Experimental Neuroimaging Laboratory, Department of Neurology and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC, USA
| | - Tiing-Yee Siow
- Department of Medical Imaging and Intervention, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan
| | - Yi-Hua Hsu
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Chiao-Chi V Chen
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Teng-Nan Lin
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Fu-Shan Jaw
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Chen Chang
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
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Selective neuronal loss in ischemic stroke and cerebrovascular disease. J Cereb Blood Flow Metab 2014; 34:2-18. [PMID: 24192635 PMCID: PMC3887360 DOI: 10.1038/jcbfm.2013.188] [Citation(s) in RCA: 169] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 10/15/2013] [Accepted: 10/17/2013] [Indexed: 01/23/2023]
Abstract
As a sequel of brain ischemia, selective neuronal loss (SNL)-as opposed to pannecrosis (i.e. infarction)-is attracting growing interest, particularly because it is now detectable in vivo. In acute stroke, SNL may affect the salvaged penumbra and hamper functional recovery following reperfusion. Rodent occlusion models can generate SNL predominantly in the striatum or cortex, showing that it can affect behavior for weeks despite normal magnetic resonance imaging. In humans, SNL in the salvaged penumbra has been documented in vivo mainly using positron emission tomography and (11)C-flumazenil, a neuronal tracer validated against immunohistochemistry in rodent stroke models. Cortical SNL has also been documented using this approach in chronic carotid disease in association with misery perfusion and behavioral deficits, suggesting that it can result from chronic or unstable hemodynamic compromise. Given these consequences, SNL may constitute a novel therapeutic target. Selective neuronal loss may also develop at sites remote from infarcts, representing secondary 'exofocal' phenomena akin to degeneration, potentially related to poststroke behavioral or mood impairments again amenable to therapy. Further work should aim to better characterize the time course, behavioral consequences-including the impact on neurological recovery and contribution to vascular cognitive impairment-association with possible causal processes such as microglial activation, and preventability of SNL.
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Carrera E, Jones PS, Morris RS, Alawneh J, Hong YT, Aigbirhio FI, Fryer TD, Carpenter TA, Warburton EA, Baron JC. Is neural activation within the rescued penumbra impeded by selective neuronal loss? Brain 2013; 136:1816-29. [DOI: 10.1093/brain/awt112] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Stroke neuroprotection: targeting mitochondria. Brain Sci 2013; 3:540-60. [PMID: 24961414 PMCID: PMC4061853 DOI: 10.3390/brainsci3020540] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/08/2013] [Accepted: 04/09/2013] [Indexed: 11/17/2022] Open
Abstract
Stroke is the fourth leading cause of death and the leading cause of long-term disability in the United States. Blood flow deficit results in an expanding infarct core with a time-sensitive peri-infarct penumbra that is considered salvageable and is the primary target for treatment strategies. The only current FDA-approved drug for treating ischemic stroke is recombinant tissue plasminogen activator (rt-PA). However, this treatment is limited to within 4.5 h of stroke onset in a small subset of patients. The goal of this review is to focus on mitochondrial-dependent therapeutic agents that could provide neuroprotection following stroke. Dysfunctional mitochondria are linked to neurodegeneration in many disease processes including stroke. The mechanisms reviewed include: (1) increasing ATP production by purinergic receptor stimulation, (2) decreasing the production of ROS by superoxide dismutase, or (3) increasing antioxidant defenses by methylene blue, and their benefits in providing neuroprotection following a stroke.
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Ejaz S, Williamson DJ, Ahmed T, Sitnikov S, Hong YT, Sawiak SJ, Fryer TD, Aigbirhio FI, Baron JC. Characterizing infarction and selective neuronal loss following temporary focal cerebral ischemia in the rat: a multi-modality imaging study. Neurobiol Dis 2012; 51:120-32. [PMID: 23146994 DOI: 10.1016/j.nbd.2012.11.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/05/2012] [Accepted: 11/01/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Current models dictate that, depending on occurrence of early reperfusion, the ischemic penumbra either undergoes or escapes infarction (i.e., "pan-necrosis"). However, tissue outcome following temporary middle-cerebral artery occlusion (tMCAo) in rodents can also include selective neuronal loss (SNL), which even if subtle may impede functional recovery. In order to explore the pathophysiology of ischemic stroke, determine potential therapeutic targets and monitor effects of therapy, in vivo imaging surrogates of these varied histopathological outcomes applicable in the clinical setting would be useful. Although hyperintense signal on T(2)-weighted MRI in the chronic post-stroke stage is considered a reliable surrogate of tissue infarction, SNL is not associated with T(2)W abnormal signal. In the clinical setting, the neuron-specific PET ligand (11)C-flumazenil (FMZ) has been used to identify both pan-necrosis and peri-infarct SNL, but this inference has not been histopathological confirmed so far. Here we investigated the late tissue sequelae of tMCAo in the rodent using in vivo T(2)W MRI and FMZ-PET against post mortem immunohistochemistry as gold standard. METHODS Adult spontaneously hypertensive rats (SHRs) underwent 45 min distal-clip middle-cerebral artery occlusion and, 28 days later, FMZ-PET and T(2)W-MRI, immediately followed by immunohistochemistry for neuronal loss (NeuN), activated microglia and astrocytosis. Based on standard histopathological definitions, ischemic lesions were classified into pan-necrosis, partial infarction or SNL. NeuN changes and FMZ binding across the whole hemisphere were quantified in the same set of 44 regions-of-interest according to previously validated protocols; linear regressions between these two measures were carried out both within and across subjects. RESULTS Both cortical pan-necrosis/partial infarction and SNL were present in all rats except one, where SNL was isolated and extensive. Infarction/partial infarction, but not SNL, was associated with T(2)W hyperintense signals and cortical atrophy. In contrast, FMZ binding was decreased in all types of lesions including SNL, in proportion with NeuN staining intensity both within (p<0.05 to <0.001) and across (p<0.001) subjects, including the subject that showed pure SNL (p=0.01). CONCLUSION This novel study revealed three main facts: i) long-term histopathological cortical changes following 45 min tMCAo in SHRs included all three of SNL, partial infarction and frank infarction; ii) T2W MRI showed conspicuous high signal lesions for complete or partial infarction, but no changes for SNL; and iii) FMZ-PET was sensitive to all three types of tMCAo-induced histopathological changes, including isolated SNL, suggesting it is a valid surrogate for the histological sequelae of focal cerebral ischemia. In addition, the finding of almost universal completed cortical infarction at 28 days differed from our previous findings at 14-day survival using the same model and rat strain, where SNL was the almost exclusive outcome, possibly representing delayed infarct maturation. Prospective studies are needed to investigate this interesting possibility.
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Affiliation(s)
- Sohail Ejaz
- Stroke Research Group, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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Duong TQ. Multimodal MRI of experimental stroke. Transl Stroke Res 2011; 3:8-15. [PMID: 24323751 DOI: 10.1007/s12975-011-0140-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 12/01/2011] [Accepted: 12/05/2011] [Indexed: 10/14/2022]
Abstract
Stroke is the fourth leading cause of death and the leading cause of long-term disability in USA. Brain imaging data from experimental stroke models and stroke patients have shown that there is often a gradual progression of potentially reversible ischemic injury toward infarction. Reestablishing tissue perfusion and/or treating with neuroprotective drugs in a timely fashion are expected to salvage some ischemic tissues. Diffusion-weighted imaging based on magnetic resonance imaging (MRI) in which contrast is based on water motion can detect ischemic injury within minutes after onsets, whereas computed tomography and other imaging modalities fail to detect stroke injury for at least a few hours. Along with quantitative perfusion imaging, the perfusion-diffusion mismatch which approximates the ischemic penumbra could be imaged noninvasively. This review describes recent progresses in the development and application of multimodal MRI and image analysis techniques to study ischemic tissue at risk in experimental stroke in rats.
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Affiliation(s)
- Timothy Q Duong
- Research Imaging Institute, Departments of Ophthalmology, Radiology and Physiology, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX, 78229, USA,
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Berthet C, Lei H, Gruetter R, Hirt L. Early Predictive Biomarkers for Lesion After Transient Cerebral Ischemia. Stroke 2011; 42:799-805. [DOI: 10.1161/strokeaha.110.603647] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Despite the improving imaging techniques, it remains challenging to predict the outcome early after transient cerebral ischemia. The aim of this study was thus to identify early metabolic biomarkers for outcome prediction.
Methods—
We modeled transient ischemic attacks and strokes in mice. Using high-field MR spectroscopy, we correlated early changes in the neurochemical profile of the ischemic striatum with histopathologic alterations at a later time point.
Results—
A significant increase in glutamine was measured between 3 hours and 8 hours after all ischemic events followed by reperfusion independently of the outcome and can thus be considered as an indicator of recent transient ischemia. On the other hand, a reduction of the score obtained by summing the concentrations of N-acetyl aspartate, glutamate, and taurine was a good predictor of an irreversible lesion as early as 3 hours after ischemia.
Conclusions—
We identified biomarkers of reversible and irreversible ischemic damage, which can be used in an early predictive evaluation of stroke outcome.
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Affiliation(s)
- Carole Berthet
- From the Department of Clinical Neurosciences (C.B., L.H.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; the Laboratory of Functional and Metabolic Imaging (H.L., R.G.), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; the Department of Radiology (H.L., R.G.), University of Lausanne, Lausanne, Switzerland; and the Department of Radiology (R.G.), University of Geneva, Geneva, Switzerland
| | - Hongxia Lei
- From the Department of Clinical Neurosciences (C.B., L.H.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; the Laboratory of Functional and Metabolic Imaging (H.L., R.G.), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; the Department of Radiology (H.L., R.G.), University of Lausanne, Lausanne, Switzerland; and the Department of Radiology (R.G.), University of Geneva, Geneva, Switzerland
| | - Rolf Gruetter
- From the Department of Clinical Neurosciences (C.B., L.H.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; the Laboratory of Functional and Metabolic Imaging (H.L., R.G.), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; the Department of Radiology (H.L., R.G.), University of Lausanne, Lausanne, Switzerland; and the Department of Radiology (R.G.), University of Geneva, Geneva, Switzerland
| | - Lorenz Hirt
- From the Department of Clinical Neurosciences (C.B., L.H.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland; the Laboratory of Functional and Metabolic Imaging (H.L., R.G.), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; the Department of Radiology (H.L., R.G.), University of Lausanne, Lausanne, Switzerland; and the Department of Radiology (R.G.), University of Geneva, Geneva, Switzerland
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Affiliation(s)
- Dae-Yul Kim
- Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College Medicine, Korea
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20
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Different strokes for different folks: the rich diversity of animal models of focal cerebral ischemia. J Cereb Blood Flow Metab 2010; 30:1412-31. [PMID: 20485296 PMCID: PMC2949237 DOI: 10.1038/jcbfm.2010.66] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
No single animal model is able to encompass all of the variables known to affect human ischemic stroke. This review highlights the major strengths and weaknesses of the most commonly used animal models of acute ischemic stroke in the context of matching model and experimental aim. Particular emphasis is placed on the relationships between outcome and underlying vascular variability, physiologic control, and use of models of comorbidity. The aim is to provide, for novice and expert alike, an overview of the key controllable determinants of experimental stroke outcome to help ensure the most effective application of animal models to translational research.
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Sicard KM, Fisher M. Animal models of focal brain ischemia. EXPERIMENTAL & TRANSLATIONAL STROKE MEDICINE 2009; 1:7. [PMID: 20150985 PMCID: PMC2820445 DOI: 10.1186/2040-7378-1-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 11/13/2009] [Indexed: 11/25/2022]
Abstract
Stroke is a leading cause of disability and death in many countries. Understanding the pathophysiology of ischemic injury and developing therapies is an important endeavor that requires much additional research. Animal stroke models provide an important mechanism for these activities. A large number of stroke models have been developed and are currently used in laboratories around the world. These models are overviewed as are approaches for measuring infarct size and functional outcome.
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Affiliation(s)
- Kenneth M Sicard
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01453, USA
| | - Marc Fisher
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01453, USA
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22
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Functional MRI of postnatal visual development in normal and hypoxic-ischemic-injured superior colliculi. Neuroimage 2009; 49:2013-20. [PMID: 19879366 DOI: 10.1016/j.neuroimage.2009.10.069] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 10/17/2009] [Accepted: 10/23/2009] [Indexed: 11/22/2022] Open
Abstract
The superior colliculus (SC) is a laminated subcortical structure in the mammalian midbrain, whose superficial layers receive visual information from the retina and the visual cortex. To date, its functional organization and development in the visual system remain largely unknown. This study employed blood oxygenation level-dependent (BOLD) functional MRI to evaluate the visual responses of the SC in normally developing and severe neonatal hypoxic-ischemic (HI)-injured rat brains from the time of eyelid opening to adulthood. MRI was performed to the normal animals (n=7) at postnatal days (P) 14, 21, 28 and 60. In the HI-injured group (n=7), the ipsilesional primary and secondary visual cortices were completely damaged after unilateral ligation of the left common carotid artery at P7 followed by hypoxia for 2 h, and MRI was performed at P60. Upon unilateral flash illumination, the normal contralateral SC underwent a systematic increase in BOLD signal amplitude with age especially after the third postnatal week. However, no significant difference in BOLD signal increase was found between P14 and P21. These findings implied the presence of neurovascular coupling at the time of eyelid opening, and the progressive development of hemodynamic regulation in the subcortical visual system. In the HI-injured group at P60, the BOLD signal increases in both SC remained at the same level as the normal group at P28 though they were significantly lower than the normal group at P60. These observations suggested the residual visual functions on both sides of the subcortical brain, despite the damages to the entire ipsilesional visual cortex. The results of this study constitute important evidence on the progressive maturation of visual functions and hemodynamic responses in the normal subcortical brain, and its functional plasticity upon neonatal HI injury.
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Bra°tane BT, Bastan B, Fisher M, Bouley J, Henninger N. Ischemic lesion volume determination on diffusion weighted images vs. apparent diffusion coefficient maps. Brain Res 2009; 1279:182-8. [DOI: 10.1016/j.brainres.2009.05.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Revised: 05/01/2009] [Accepted: 05/02/2009] [Indexed: 10/20/2022]
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Neuronal plasticity after ischemic preconditioning and TIA-like preconditioning ischemic periods. Acta Neuropathol 2009; 117:511-23. [PMID: 19084975 DOI: 10.1007/s00401-008-0473-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 11/29/2008] [Accepted: 12/06/2008] [Indexed: 01/10/2023]
Abstract
Transient ischemic attacks (TIAs) have recently become the center of attention since they are thought to share some characteristics with experimental ischemic preconditioning (IPC). This phenomenon describes the situation that a brief, per se harmless, cerebral ischemic period renders the brain resistant to a subsequent severe and normally damaging ischemia. Preconditioning (PC) is not restricted to the brain but also occurs in other organs. Furthermore, apart from a short ischemia, the PC event may comprise nearly any noxious stimulus which, however, must not exceed the threshold to tissue damage. In the last two decades, our knowledge concerning the underlying molecular basis of PC has substantially grown and there is hope to potentially imitate the induction of an endogenous neuroprotective state in patients with a high risk of cerebral ischemia. While, at present, there is virtually no neuropathological data on changes after TIAs or TIA-like PC ischemic periods in human brains, the following review will briefly summarize the current knowledge of plastic neuronal changes after PC in animal models, still awaiting their detection in the human brain.
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Chan KC, Khong PL, Cheung MM, Wang S, Cai KX, Wu EX. MRI of late microstructural and metabolic alterations in radiation-induced brain injuries. J Magn Reson Imaging 2009; 29:1013-20. [DOI: 10.1002/jmri.21736] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Abstract
Ischemic brain damage can be prevented or at least significantly reduced when there is a preceding brief ischemic period that does not exceed the threshold for tissue damage--a phenomenon termed "ischemic preconditioning" (ischemic PC). Experimental PC in rodents is now considered to be a model for transient ischemic attacks in humans, and there is increasing hope for translating the knowledge of underlying mechanisms in the animal models into the clinic to enhance endogenous neuroprotective mechanisms in patients with stroke. However, although PC was originally defined as a subtoxic stimulus without any morphologic damage, there is a growing body of evidence from studies using sensitive techniques that postischemic structural alterations of brain tissue manifest not only after ischemia with prior PC but also after the PC stimulus itself. Furthermore, it has become evident over time that the primary shortcomings of many experimental studies on PC are the short observation intervals. The few studies with extended postischemic survival periods done to date provide clear evidence of considerable structural changes and even cell death, which may only be postponed by PC. Therefore, further studies are needed to elucidate structural long-term changes after PC and to validate the persistence of the neuroprotective effects.
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27
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Henninger N, Sicard KM, Li Z, Kulkarni P, Dützmann S, Urbanek C, Schwab S, Fisher M. Differential recovery of behavioral status and brain function assessed with functional magnetic resonance imaging after mild traumatic brain injury in the rat. Crit Care Med 2008; 35:2607-14. [PMID: 17828037 DOI: 10.1097/01.ccm.0000286395.79654.8d] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The relationship between cerebral integrity, recovery of brain function, and neurologic status after mild traumatic brain injury is incompletely characterized. DESIGN Prospective and randomized study in rodents. SETTING University laboratory. SUBJECTS Male Wistar rats (290-310 g). INTERVENTIONS In rats, quantitative diffusion weighted imaging (DWI), perfusion weighted imaging (PWI), T2-weighted imaging (T2WI), and functional magnetic resonance imaging (fMRI) were performed up to 21 days after weight-induced, closed-head, mild traumatic brain injury (MTBI, n = 6) or sham operation (n = 6). Pixel-by-pixel analysis and region of interest analysis were used to evaluate structural (apparent diffusion coefficient [ADC] and basal cerebral blood flow [bCBF]) and functional magnetic resonance signal changes within the brain, respectively. Quantitative fMRI signal changes were correlated with behavioral measures. MEASUREMENTS AND MAIN RESULTS Despite normal appearing DWI and T2WI findings following MTBI, persistent hypoperfusion developed that was not associated with cytotoxic edema. In contrast, the ADC was significantly increased by approximately 5% at 1 and 7 days post-MTBI. Post-MTBI fMRI responses to hypercapnia and forepaw stimulation were significantly impaired and showed a differential recovery rate between and within investigated region of interests. Significant dysfunction in forepaw placement test persisted up to day 1 and correlated significantly with fMRI signal changes in the primary somatosensory and motor cortices. CONCLUSIONS MTBI produced distinct changes on multimodal MRI and behavioral variables acutely and chronically. Following MTBI, fMRI and ADC-bCBF pixel-by-pixel analysis identified subtle structural and functional alterations in the brain that appeared completely normal on conventional DWI and T2WI after concussion injury. The former techniques may therefore provide great potential for understanding mild traumatic brain injury, identifying mechanisms underlying recovery, and investigating specific interventions to enhance functional outcome.
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Affiliation(s)
- Nils Henninger
- Department of Internal Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
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28
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Cho YR, Pawela CP, Li R, Kao D, Schulte ML, Runquist ML, Yan JG, Matloub HS, Jaradeh SS, Hudetz AG, Hyde JS. Refining the sensory and motor ratunculus of the rat upper extremity using fMRI and direct nerve stimulation. Magn Reson Med 2008; 58:901-9. [PMID: 17969116 DOI: 10.1002/mrm.21408] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It is well understood that the different regions of the body have cortical representations in proportion to the degree of innervation. Our current understanding of the rat upper extremity has been enhanced using functional MRI (fMRI), but these studies are often limited to the rat forepaw. The purpose of this study is to describe a new technique that allows us to refine the sensory and motor representations in the cerebral cortex by surgically implanting electrodes on the major nerves of the rat upper extremity and providing direct electrical nerve stimulation while acquiring fMRI images. This technique was used to stimulate the ulnar, median, radial, and musculocutaneous nerves in the rat upper extremity using four different stimulation sequences that varied in frequency (5 Hz vs. 10 Hz) and current (0.5 mA vs. 1.0 mA). A distinct pattern of cortical activation was found for each nerve. The higher stimulation current resulted in a dramatic increase in the level of cortical activation. The higher stimulation frequency resulted in both increases and attenuation of cortical activation in different regions of the brain, depending on which nerve was stimulated.
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Affiliation(s)
- Younghoon R Cho
- Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Henninger N, Sicard KM, Fisher M. Spectacular shrinking deficit: insights from multimodal magnetic resonance imaging after embolic middle cerebral artery occlusion in Sprague-Dawley rats. J Cereb Blood Flow Metab 2007; 27:1756-63. [PMID: 17377514 DOI: 10.1038/sj.jcbfm.9600477] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Almost no data is available on the serial changes in the brain after spectacular shrinking deficit (SSD) that may help understand this relatively rare clinical phenomenon. Quantitative diffusion-(DWI), perfusion-(PWI), T(1)-(T1WI), T(2)-weighted (T2WI), and functional magnetic resonance imaging (fMRI) were performed before, during, and up to 7 days after embolic middle cerebral artery occlusion (eMCAO) in male Sprague-Dawley rats (n=9). Region of interest (ROI) analysis was used to evaluate structural and functional MR signal changes within three ROIs defined by the apparent diffusion coefficient (ADC), cerebral blood flow (CBF) signatures, and final tissue viability. DWI, PWI, and T2WI lesion volumes were calculated using previously established viability thresholds and final infarct volumes ascertained with 2,3,5-triphenyltetrazolium chloride (TTC) staining. Serial MRI demonstrated spontaneous reperfusion of initially hypoperfused MCA regions accompanied by substantial reduction of initial ADC and CBF lesions and gradual recovery of neurological outcome. Recovery rates of CBF/ADC abnormalities differed among ROIs. Functional magnetic resonance imaging showed persistent tissue dysfunction after the recovery of the CBF/ADC lesions. This study may facilitate our understanding of the pathophysiological mechanisms by which early, spontaneous reperfusion affects tissue fate and neurological function.
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Affiliation(s)
- Nils Henninger
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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Sicard KM, Henninger N, Fisher M, Duong TQ, Ferris CF. Long-term changes of functional MRI-based brain function, behavioral status, and histopathology after transient focal cerebral ischemia in rats. Stroke 2006; 37:2593-600. [PMID: 16946164 PMCID: PMC2949951 DOI: 10.1161/01.str.0000239667.15532.c1] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The relation between recovery of brain function and neurological status after clinical and experimental cerebral ischemia is incompletely characterized. We assessed the evolution of ischemic injury, behavioral status, and brain activity at acute to chronic periods after transient middle cerebral artery occlusion (tMCAO) in rats. METHODS Male Sprague-Dawley rats were subjected to 20-minute tMCAO (n=10) or sham operation (n=10). Sensorimotor behavioral testing and multimodal (diffusion, perfusion, T2, and functional) MRI, as well as postmortem hematoxylin-eosin staining, were performed before and up to 21 days after tMCAO. MRI and histological parameters were evaluated in 5 regions of interest within the sensorimotor network. Diffusion, perfusion, and T2 lesion volumes were calculated according to previously established viability thresholds. RESULTS Diffusion and perfusion lesions were present during occlusion but disappeared completely and permanently within 30 minutes after reperfusion, with no T2 lesions seen. Functional MRI and behavioral deficits did not normalize until 1 and 21 days after tMCAO, respectively. Histology demonstrated selective neuronal cell death at 7 and 21 days after reperfusion. CONCLUSIONS Twenty-minute tMCAO produced distinct changes on multimodal MRI, histology, and behavioral parameters acutely and chronically. Normal findings on MRI after transient ischemia may not indicate normal tissue status, as behavioral and histological anomalies remain. Behavioral dysfunction persisting long after the recovery of MRI parameters may relate to the subtle neuronal damage seen on histology. Together, these results may help explain unremitting neurological deficits in stroke or transient ischemic attack patients with normal MRI findings.
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MESH Headings
- Animals
- Behavior, Animal
- Brain/pathology
- Brain/physiopathology
- Brain Damage, Chronic/etiology
- Brain Damage, Chronic/pathology
- Brain Damage, Chronic/psychology
- Cell Death
- Diffusion Magnetic Resonance Imaging
- Hypercapnia/physiopathology
- Infarction, Middle Cerebral Artery/complications
- Infarction, Middle Cerebral Artery/pathology
- Infarction, Middle Cerebral Artery/physiopathology
- Infarction, Middle Cerebral Artery/psychology
- Ischemic Attack, Transient/complications
- Ischemic Attack, Transient/pathology
- Ischemic Attack, Transient/physiopathology
- Ischemic Attack, Transient/psychology
- Magnetic Resonance Imaging
- Male
- Movement Disorders/etiology
- Movement Disorders/pathology
- Movement Disorders/physiopathology
- Neurons/pathology
- Perceptual Disorders/etiology
- Perceptual Disorders/pathology
- Perceptual Disorders/physiopathology
- Rats
- Rats, Sprague-Dawley
- Reaction Time
- Sensation Disorders/etiology
- Sensation Disorders/pathology
- Sensation Disorders/physiopathology
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Affiliation(s)
- Kenneth M Sicard
- Center for Comparative Neuroimaging, University of Massachusetts Medical School, 303 Belmont St, Worcester, MA 01604, USA.
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