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Yu J, Joo IL, Bazzigaluppi P, Koletar MM, Cherin E, Stanisz AG, Graham JWC, Demore C, Stefanovic B. Micro-ultrasound based characterization of cerebrovasculature following focal ischemic stroke and upon short-term rehabilitation. J Cereb Blood Flow Metab 2024; 44:461-476. [PMID: 37974304 PMCID: PMC10981404 DOI: 10.1177/0271678x231215004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/21/2023] [Accepted: 10/27/2023] [Indexed: 11/19/2023]
Abstract
Notwithstanding recanalization treatments in the acute stage of stroke, many survivors suffer long-term impairments. Physical rehabilitation is the only widely available strategy for chronic-stage recovery, but its optimization is hindered by limited understanding of its effects on brain structure and function. Using micro-ultrasound, behavioral testing, and electrophysiology, we investigated the impact of skilled reaching rehabilitation on cerebral hemodynamics, motor function, and neuronal activity in a rat model of focal ischemic stroke. A 50 MHz micro-ultrasound transducer and intracortical electrophysiology were utilized to characterize neurovascular changes three weeks following focal ischemia elicited by endothelin-1 injection into the sensorimotor cortex. Sprague-Dawley rats were rehabilitated through tray reaching, and their fine skilled reaching was assessed via the Montoya staircase. Focal ischemia led to a sustained deficit in forelimb reaching; and increased tortuosity of the penetrating vessels in the perilesional cortex; with no lateralization of spontaneous neuronal activity. Rehabilitation improved skilled reaching; decreased cortical vascularity; was associated with elevated peri- vs. contralesional hypercapnia-induced flow homogenization and increased perilesional spontaneous cortical neuronal activity. Our study demonstrated neurovascular plasticity accompanying rehabilitation-elicited functional recovery in the subacute stage following stroke, and multiple micro-ultrasound-based markers of cerebrovascular structure and function modified in recovery from ischemia and upon rehabilitation.
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Affiliation(s)
- Johnson Yu
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Illsung L Joo
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Paolo Bazzigaluppi
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- MetaCell, Cagliari, Italy
| | - Margaret M Koletar
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Emmanuel Cherin
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Andrew G Stanisz
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - James WC Graham
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Christine Demore
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
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2
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Ringuette D, EbrahimAmini A, Sangphosuk W, Aquilino MS, Carroll G, Ashley M, Bazzigaluppi P, Dufour S, Droguerre M, Stefanovic B, Levi O, Charveriat M, Monnier PP, Carlen PL. Spreading depolarization suppression from inter-astrocytic gap junction blockade assessed with multimodal imaging and a novel wavefront detection scheme. Neurotherapeutics 2024; 21:e00298. [PMID: 38241157 PMCID: PMC10903093 DOI: 10.1016/j.neurot.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/07/2023] [Indexed: 01/21/2024] Open
Abstract
Spreading depolarizations (SDs) are an enigmatic and ubiquitous co-morbidity of neural dysfunction. SDs are propagating waves of local field depolarization and increased extracellular potassium. They increase the metabolic demand on brain tissue, resulting in changes in tissue blood flow, and are associated with adverse neurological consequences including stroke, epilepsy, neurotrauma, and migraine. Their occurrence is associated with poor patient prognosis through mechanisms which are only partially understood. Here we show in vivo that two (structurally dissimilar) drugs, which suppress astroglial gap junctional communication, can acutely suppress SDs. We found that mefloquine hydrochloride (MQH), administered IP, slowed the propagation of the SD potassium waveform and intermittently led to its suppression. The hemodynamic response was similarly delayed and intermittently suppressed. Furthermore, in instances where SD led to transient tissue swelling, MQH reduced observable tissue displacement. Administration of meclofenamic acid (MFA) IP was found to reduce blood flow, both proximal and distal, to the site of SD induction, preceding a large reduction in the amplitude of the SD-associated potassium wave. We introduce a novel image processing scheme for SD wavefront localization under low-contrast imaging conditions permitting full-field wavefront velocity mapping and wavefront parametrization. We found that MQH administration delayed SD wavefront's optical correlates. These two clinically used drugs, both gap junctional blockers found to distinctly suppress SDs, may be of therapeutic benefit in the various brain disorders associated with recurrent SDs.
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Affiliation(s)
- Dene Ringuette
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada.
| | - Azin EbrahimAmini
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Weerawong Sangphosuk
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada
| | - Mark S Aquilino
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Gwennyth Carroll
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Max Ashley
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada
| | - Paolo Bazzigaluppi
- Sunnybrook Health Sciences Center, 2075 Bayview Ave., Toronto, Ontario M4N 3M5, Canada
| | - Suzie Dufour
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | | | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto, Ontario M5G 2M9, Canada; Sunnybrook Health Sciences Center, 2075 Bayview Ave., Toronto, Ontario M4N 3M5, Canada
| | - Ofer Levi
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada; The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Rd., Toronto, Ontario M5S 3G4, Canada
| | | | - Philippe P Monnier
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Department of Ophthalmology & Vision Science, Faculty of Medicine, University of Toronto, 340 College St., Toronto, Ontario M5T 3A9, Canada
| | - Peter L Carlen
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
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3
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Lai AY, Bazzigaluppi P, Morrone CD, Hill ME, Stefanovic B, McLaurin J. Compromised Cortical-Hippocampal Network Function From Transient Hypertension: Linking Mid-Life Hypertension to Late Life Dementia Risk. Front Neurosci 2022; 16:897206. [PMID: 35812238 PMCID: PMC9260147 DOI: 10.3389/fnins.2022.897206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 06/06/2022] [Indexed: 11/20/2022] Open
Abstract
Mid-life hypertension is a major risk factor for developing dementia later in life. While anti-hypertensive drugs restore normotension, dementia risk remains above baseline suggesting that brain damage sustained during transient hypertension is irreversible. The current study characterized a rat model of transient hypertension with an extended period of normotensive recovery: F344 rats were treated with L-NG-Nitroarginine methyl ester (L-NAME) for 1 month to induce hypertension then allowed up to 4 months of recovery. With respect to cognitive deficits, comparison between 1 month and 4 months of recovery identified initial deficits in spatial memory that resolved by 4 months post-hypertension; contrastingly, loss of cognitive flexibility did not. The specific cells and brain regions underlying these cognitive deficits were investigated. Irreversible structural damage to the brain was observed in both the prefrontal cortex and the hippocampus, with decreased blood vessel density, myelin and neuronal loss. We then measured theta-gamma phase amplitude coupling as a readout for network function, a potential link between the observed cognitive and pathological deficits. Four months after hypertension, we detected decreased theta-gamma phase amplitude coupling within each brain region and a concurrent increase in baseline connectivity between the two regions reflecting an attempt to maintain function that may account for the improvement in spatial memory. Our results demonstrate that connectivity between prefrontal cortex and hippocampus is a vulnerable network affected by transient hypertension which is not rescued over time; thus demonstrating for the first time a mechanistic link between the long-term effects of transient hypertension and dementia risk.
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Affiliation(s)
- Aaron Y. Lai
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
- *Correspondence: Aaron Y. Lai,
| | - Paolo Bazzigaluppi
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | | | - Mary E. Hill
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
| | - JoAnne McLaurin
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
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4
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Bazzigaluppi P, Mester J, Joo IL, Weisspapir I, Dorr A, Koletar MM, Beckett TL, Khosravani H, Carlen P, Stefanovic B. Frequency selective neuronal modulation triggers spreading depolarizations in the rat endothelin-1 model of stroke. J Cereb Blood Flow Metab 2021; 41:2756-2768. [PMID: 33969731 PMCID: PMC8504421 DOI: 10.1177/0271678x211013656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ischemia is one of the most common causes of acquired brain injury. Central to its noxious sequelae are spreading depolarizations (SDs), waves of persistent depolarizations which start at the location of the flow obstruction and expand outwards leading to excitotoxic damage. The majority of acute stage of stroke studies to date have focused on the phenomenology of SDs and their association with brain damage. In the current work, we investigated the role of peri-injection zone pyramidal neurons in triggering SDs by optogenetic stimulation in an endothelin-1 rat model of focal ischemia. Our concurrent two photon fluorescence microscopy data and local field potential recordings indicated that a ≥ 60% drop in cortical arteriolar red blood cell velocity was associated with SDs at the ET-1 injection site. SDs were also observed in the peri-injection zone, which subsequently exhibited elevated neuronal activity in the low-frequency bands. Critically, SDs were triggered by low- but not high-frequency optogenetic stimulation of peri-injection zone pyramidal neurons. Our findings depict a complex etiology of SDs post focal ischemia and reveal that effects of neuronal modulation exhibit spectral and spatial selectivity.
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Affiliation(s)
- Paolo Bazzigaluppi
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
- Paolo Bazzigaluppi, Sunnybrook Research Institute, 2075 Bayview Ave., S646, Toronto, ON M4N 3M5, Canada.
| | - James Mester
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
- Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Illsung L Joo
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
| | - Iliya Weisspapir
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
| | - Adrienne Dorr
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
| | | | - Tina L Beckett
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
| | - Houman Khosravani
- Division of Neurology and Interdepartmental Division of Critical Care, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
- Interdepartmental Division of Critical Care, Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Peter Carlen
- Krembil Research Institute, University of Toronto, Toronto, ON, Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Physical Sciences, Toronto, ON, Canada
- Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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5
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Mester JR, Bazzigaluppi P, Dorr A, Beckett T, Burke M, McLaurin J, Sled JG, Stefanovic B. Attenuation of tonic inhibition prevents chronic neurovascular impairments in a Thy1-ChR2 mouse model of repeated, mild traumatic brain injury. Am J Cancer Res 2021; 11:7685-7699. [PMID: 34335958 PMCID: PMC8315057 DOI: 10.7150/thno.60190] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 06/04/2021] [Indexed: 12/24/2022] Open
Abstract
Rationale: Mild traumatic brain injury (mTBI), the most common type of brain trauma, frequently leads to chronic cognitive and neurobehavioral deficits. Intervening effectively is impeded by our poor understanding of its pathophysiological sequelae. Methods: To elucidate the long-term neurovascular sequelae of mTBI, we combined optogenetics, two-photon fluorescence microscopy, and intracortical electrophysiological recordings in mice to selectively stimulate peri-contusional neurons weeks following repeated closed-head injury and probe individual vessel's function and local neuronal reactivity. Results: Compared to sham-operated animals, mTBI mice showed doubled cortical venular speeds (115 ± 25%) and strongly elevated cortical venular reactivity (53 ± 17%). Concomitantly, the pericontusional neurons exhibited attenuated spontaneous activity (-57 ± 79%) and decreased reactivity (-47 ± 28%). Post-mortem immunofluorescence revealed signs of peri-contusional senescence and DNA damage, in the absence of neuronal loss or gliosis. Alteration of neuronal and vascular functioning was largely prevented by chronic, low dose, systemic administration of a GABA-A receptor inverse agonist (L-655,708), commencing 3 days following the third impact. Conclusions: Our findings indicate that repeated mTBI leads to dramatic changes in the neurovascular unit function and that attenuation of tonic inhibition can prevent these alterations. The sustained disruption of the neurovascular function may underlie the concussed brain's long-term susceptibility to injury, and calls for development of better functional assays as well as of neurovascularly targeted interventions.
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6
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Morrone CD, Bazzigaluppi P, Beckett TL, Hill ME, Koletar MM, Stefanovic B, McLaurin J. Regional differences in Alzheimer's disease pathology confound behavioural rescue after amyloid-β attenuation. Brain 2020; 143:359-373. [PMID: 31782760 PMCID: PMC6935751 DOI: 10.1093/brain/awz371] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 09/16/2019] [Accepted: 10/01/2019] [Indexed: 12/31/2022] Open
Abstract
Failure of Alzheimer’s disease clinical trials to improve or stabilize cognition has led to the need for a better understanding of the driving forces behind cognitive decline in the presence of active disease processes. To dissect contributions of individual pathologies to cognitive function, we used the TgF344-AD rat model, which recapitulates the salient hallmarks of Alzheimer’s disease pathology observed in patient populations (amyloid, tau inclusions, frank neuronal loss, and cognitive deficits). scyllo-Inositol treatment attenuated amyloid-β peptide in disease-bearing TgF344-AD rats, which rescued pattern separation in the novel object recognition task and executive function in the reversal learning phase of the Barnes maze. Interestingly, neither activities of daily living in the burrowing task nor spatial memory in the Barnes maze were rescued by attenuating amyloid-β peptide. To understand the pathological correlates leading to behavioural rescue, we examined the neuropathology and in vivo electrophysiological signature of the hippocampus. Amyloid-β peptide attenuation reduced hippocampal tau pathology and rescued adult hippocampal neurogenesis and neuronal function, via improvements in cross-frequency coupling between theta and gamma bands. To investigate mechanisms underlying the persistence of spatial memory deficits, we next examined neuropathology in the entorhinal cortex, a region whose input to the hippocampus is required for spatial memory. Reduction of amyloid-β peptide in the entorhinal cortex had no effect on entorhinal tau pathology or entorhinal-hippocampal neuronal network dysfunction, as measured by an impairment in hippocampal response to entorhinal stimulation. Thus, rescue or not of cognitive function is dependent on regional differences of amyloid-β, tau and neuronal network dysfunction, demonstrating the importance of staging disease in patients prior to enrolment in clinical trials. These results further emphasize the need for combination therapeutic approaches across disease progression.
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Affiliation(s)
- Christopher D Morrone
- Sunnybrook Research Institute, Biological Sciences, 2075 Bayview Ave, Toronto, ON, Canada.,University of Toronto, Faculty of Medicine, Department of Laboratory Medicine and Pathobiology, 1 King's College Cir, Toronto, ON, Canada
| | - Paolo Bazzigaluppi
- Sunnybrook Research Institute, Physical Sciences, 2075 Bayview Ave, Toronto, ON, Canada
| | - Tina L Beckett
- Sunnybrook Research Institute, Biological Sciences, 2075 Bayview Ave, Toronto, ON, Canada
| | - Mary E Hill
- Sunnybrook Research Institute, Biological Sciences, 2075 Bayview Ave, Toronto, ON, Canada
| | - Margaret M Koletar
- Sunnybrook Research Institute, Physical Sciences, 2075 Bayview Ave, Toronto, ON, Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Physical Sciences, 2075 Bayview Ave, Toronto, ON, Canada.,University of Toronto, Faculty of Medicine, Department of Medical Biophysics, 101 College St Suite 15-701, Toronto, ON, Canada
| | - JoAnne McLaurin
- Sunnybrook Research Institute, Biological Sciences, 2075 Bayview Ave, Toronto, ON, Canada.,University of Toronto, Faculty of Medicine, Department of Laboratory Medicine and Pathobiology, 1 King's College Cir, Toronto, ON, Canada
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7
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Bazzigaluppi P, Beckett TL, Koletar MM, Hill ME, Lai A, Trivedi A, Thomason L, Dorr A, Gallagher D, Librach CL, Joo IL, McLaurin J, Stefanovic B. Combinatorial Treatment Using Umbilical Cord Perivascular Cells and Aβ Clearance Rescues Vascular Function Following Transient Hypertension in a Rat Model of Alzheimer Disease. Hypertension 2019; 74:1041-1051. [PMID: 31476904 PMCID: PMC6739147 DOI: 10.1161/hypertensionaha.119.13187] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Supplemental Digital Content is available in the text. Transient hypertension is a risk factor for Alzheimer disease (AD), but the effects of this interaction on brain vasculature are understudied. Addressing vascular pathology is a promising avenue to potentiate the efficacy of treatments for AD. We used arterial spin labeling magnetic resonance imaging to longitudinally assess brain vascular function and immunohistopathology to examine cerebrovascular remodeling and amyloid load. Hypertension was induced for 1 month by administration of l-NG-nitroarginine-methyl-ester in TgF344-AD rats at the prodromal stage. Following hypertension, nontransgenic rats showed transient cerebrovascular changes, whereas TgF344-AD animals exhibited sustained alterations in cerebrovascular function. Human umbilical cord perivascular cells in combination with scyllo-inositol, an inhibitor of Aβ oligomerization, resulted in normalization of hippocampal vascular function and remodeling, in contrast to either treatment alone. Prodromal stage hypertension exacerbates latter AD pathology, and the combination of human umbilical cord perivascular cells with amyloid clearance promotes cerebrovascular functional recovery.
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Affiliation(s)
- Paolo Bazzigaluppi
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Tina L Beckett
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Margaret M Koletar
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Mary E Hill
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Aaron Lai
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Arunachala Trivedi
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Lynsie Thomason
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Adrienne Dorr
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | | | - Clifford L Librach
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.).,Division of Obstetrics and Gynaecology, Laboratory Medicine and Pathobiology (C.L.), University of Toronto, Canada.,CReATe Research Program, Toronto, Canada (D.G., C.L.L.)
| | - Illsung L Joo
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - JoAnne McLaurin
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.)
| | - Bojana Stefanovic
- From the Sunnybrook Research Institute, Toronto, Canada (P.B., T.L.B., M.M.K., M.E.H., A.L., A.T., L.T., A.D., C.L.L., I.L.J., J.M., B.S.).,Department of Medical Biophysics (B.S.), University of Toronto, Canada
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8
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Bazzigaluppi P, Beckett T, Koletar M, Lai A, Morrone C, Smolina A, McLaurin J, Stefanovic B. Abstract WP566: Vascular Regeneration Following Transient Hypertension by Perivascular Progenitor Cells and Abeta Clearance in a Transgenic Rat Model of Alzheimer’S Disease. Stroke 2019. [DOI: 10.1161/str.50.suppl_1.wp566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The interplay between hypertension and amyloidogensis is understudied and lacks of preclinical model that captures both pathologies. Our therapeutic approach is designed to target the patients who present cerebrovascular injury in combination with AD pathology. We combined induced transient hypertension (via Nω-nitro-L-arginine methyl ester hydrochloride, L-NAME) in a transgenic rat model of AD that recapitulates Aβ peptide deposition and tau hyperphosphorylation in the adulthood followed by cognitive decline and neuronal loss in later life. We administered human umbilical cord perivascular cells (HUCPVC) to elicit brain vascular repair and scyllo-inositol (SI) to clear amyloid. Treatment outcomes were measured by perfusion MRI, immunohistochemistry (amyloid, tau hyperphosphorylation, vascular markers), and immunoblotting. Four weeks after the cessation of L-NAME, a single HUCPVC treatment was administered, and final imaging session conducted four weeks thereafter. Blood-flow was measured during both rest and CO
2
challenges at: baseline, immediately post-L-NAME, and at endpoint. L-NAME administration induced moderate hypertension in both TgAD-F344 and non-TgAD rats, manifested by increased systolic pressure, elevated plasminogen activator inhibitor-1, decreased vessel density and hippocampal resting perfusion reduction. Hippocampal hypoperfusion in the non-TgAD animals returned to baseline 4-weeks after cessation of L-NAME, whereas in TgAD-F344 rats it persisted until endpoint and was not rescued by HUCPVC+SI. Hippocampal vascular responsivity to hypercapnia increased twice as much in TgAD-F344 when compared to non-TgAD-F344 following L-NAME administration; it did not return to baseline levels 4-weeks after cessation of L-NAME in the vehicle-administered TgAD-F344 rats, whereas HUCPVC and HUCPVC+SI rescued hippocampal cerebrovascular hyperreactivity to baseline levels of TgAD-F344 rats. Transient hypertension caused sustained cerebrovascular dysfunction when associated with Aβ plaques, revealing an interaction between transient hypertension and AD pathology. Combinatorial treatment with SI and HUCPVC may be necessary to address cerebrovascular disease with comorbid AD.
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Affiliation(s)
| | | | | | - Aaron Lai
- Sunnybrook Rsch Institute, Toronto, Canada
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9
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Bazzigaluppi P, Adams C, Koletar MM, Dorr A, Pikula A, Carlen PL, Stefanovic B. Oophorectomy Reduces Estradiol Levels and Long-Term Spontaneous Neurovascular Recovery in a Female Rat Model of Focal Ischemic Stroke. Front Mol Neurosci 2018; 11:338. [PMID: 30271324 PMCID: PMC6146137 DOI: 10.3389/fnmol.2018.00338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/28/2018] [Indexed: 12/31/2022] Open
Abstract
Although epidemiological evidence suggests significant sex and gender-based differences in stroke risk and recovery, females have been widely under-represented in preclinical stroke research. The neurovascular sequelae of brain ischemia in females, in particular, are largely uncertain. We set out to address this gap by a multimodal in vivo study of neurovascular recovery from endothelin-1 model of cortical focal-stroke in sham vs. ovariectomized female rats. Three weeks post ischemic insult, sham operated females recapitulated the phenotype previously reported in male rats in this model, of normalized resting perfusion but sustained peri-lesional cerebrovascular hyperreactivity. In contrast, ovariectomized (Ovx) females showed reduced peri-lesional resting blood flow, and elevated cerebrovascular responsivity to hypercapnia in the peri-lesional and contra-lateral cortices. Electrophysiological recordings showed an attenuation of theta to low-gamma phase-amplitude coupling in the peri-lesional tissue of Ovx animals, despite relative preservation of neuronal power. Further, this chronic stage neuronal network dysfunction was inversely correlated with serum estradiol concentration. Our pioneering data demonstrate dramatic differences in spontaneous recovery in the neurovascular unit between Ovx and Sham females in the chronic stage of stroke, underscoring the importance of considering hormonal-dependent aspects of the ischemic sequelae in the development of novel therapeutic approaches and patient recruitment in clinical trials.
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Affiliation(s)
- Paolo Bazzigaluppi
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Conner Adams
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Margaret M Koletar
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Adrienne Dorr
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Aleksandra Pikula
- Adult Vascular Neurology, Toronto Western Hospital, Toronto, ON, Canada
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, Toronto, ON, Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
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10
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Adams C, Bazzigaluppi P, Beckett TL, Bishay J, Weisspapir I, Dorr A, Mester JR, Steinman J, Hirschler L, Warnking JM, Barbier EL, McLaurin J, Sled JG, Stefanovic B. Neurogliovascular dysfunction in a model of repeated traumatic brain injury. Am J Cancer Res 2018; 8:4824-4836. [PMID: 30279740 PMCID: PMC6160760 DOI: 10.7150/thno.24747] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 08/02/2018] [Indexed: 12/13/2022] Open
Abstract
Traumatic brain injury (TBI) research has focused on moderate to severe injuries as their outcomes are significantly worse than those of a mild TBI (mTBI). However, recent epidemiological evidence has indicated that a series of even mild TBIs greatly increases the risk of neurodegenerative and psychiatric disorders. Neuropathological studies of repeated TBI have identified changes in neuronal ionic concentrations, axonal injury, and cytoskeletal damage as important determinants of later life neurological and mood compromise; yet, there is a paucity of data on the contribution of neurogliovascular dysfunction to the progression of repeated TBI and alterations of brain function in the intervening period. Methods: Here, we established a mouse model of repeated TBI induced via three electromagnetically actuated impacts delivered to the intact skull at three-day intervals and determined the long-term deficits in neurogliovascular functioning in Thy1-ChR2 mice. Two weeks post the third impact, cerebral blood flow and cerebrovascular reactivity were measured with arterial spin labelling magnetic resonance imaging. Neuronal function was investigated through bilateral intracranial electrophysiological responses to optogenetic photostimulation. Vascular density of the site of impacts was measured with in vivo two photon fluorescence microscopy. Pathological analysis of neuronal survival and astrogliosis was performed via NeuN and GFAP immunofluorescence. Results: Cerebral blood flow and cerebrovascular reactivity were decreased by 50±16% and 70±20%, respectively, in the TBI cohort relative to sham-treated animals. Concomitantly, electrophysiological recordings revealed a 97±1% attenuation in peri-contusional neuronal reactivity relative to sham. Peri-contusional vascular volume was increased by 33±2% relative to sham-treated mice. Pathological analysis of the peri-contusional cortex demonstrated astrogliosis, but no changes in neuronal survival. Conclusion: This work provides the first in-situ characterization of the long-term deficits of the neurogliovascular unit following repeated TBI. The findings will help guide the development of diagnostic markers as well as therapeutics targeting neurogliovascular dysfunction.
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11
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Bazzigaluppi P, Lake EM, Beckett TL, Koletar MM, Weisspapir I, Heinen S, Mester J, Lai A, Janik R, Dorr A, McLaurin J, Stanisz GJ, Carlen PL, Stefanovic B. Imaging the Effects of β-Hydroxybutyrate on Peri-Infarct Neurovascular Function and Metabolism. Stroke 2018; 49:2173-2181. [DOI: 10.1161/strokeaha.118.020586] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Paolo Bazzigaluppi
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Sunnybrook Research Institute, Toronto, Canada; Fundamental Neurobiology, Krembil Research Institute, Toronto, Canada (P.B., I.W., P.L.C.)
| | - Evelyn M. Lake
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
| | - Tina L. Beckett
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
| | - Margaret M. Koletar
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
| | - Iliya Weisspapir
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Sunnybrook Research Institute, Toronto, Canada; Fundamental Neurobiology, Krembil Research Institute, Toronto, Canada (P.B., I.W., P.L.C.)
| | | | - James Mester
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Biological Sciences (J.M.)
| | - Aaron Lai
- Department of Laboratory Medicine and Pathobiology (A.L., J.M.)
| | - Rafal Janik
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Department of Medical Biophysics (J.M., R.J., G.J.S., B.S.), University of Toronto, Canada
| | - Adrienne Dorr
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
| | - JoAnne McLaurin
- Department of Laboratory Medicine and Pathobiology (A.L., J.M.)
- Department of Medical Biophysics (J.M., R.J., G.J.S., B.S.), University of Toronto, Canada
| | - Greg J. Stanisz
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Department of Medical Biophysics (J.M., R.J., G.J.S., B.S.), University of Toronto, Canada
| | - Peter L. Carlen
- Sunnybrook Research Institute, Toronto, Canada; Fundamental Neurobiology, Krembil Research Institute, Toronto, Canada (P.B., I.W., P.L.C.)
| | - Bojana Stefanovic
- From the Physical Sciences Platform (P.B., E.M.L., T.L.B., M.M.K., I.W., J.M., R.J., A.D., G.J.S., B.S.)
- Department of Medical Biophysics (J.M., R.J., G.J.S., B.S.), University of Toronto, Canada
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12
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Bazzigaluppi P, Isenia SC, Haasdijk ED, Elgersma Y, De Zeeuw CI, van der Giessen RS, de Jeu MTG. Modulation of Murine Olivary Connexin 36 Gap Junctions by PKA and CaMKII. Front Cell Neurosci 2017; 11:397. [PMID: 29311830 PMCID: PMC5735106 DOI: 10.3389/fncel.2017.00397] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/28/2017] [Indexed: 11/15/2022] Open
Abstract
The inferior olive (IO) is a nucleus located in the brainstem and it is part of the olivo-cerebellar loop. This circuit plays a fundamental role in generation and acquisition of coherent motor patterns and it relies on synchronous activation of groups of Purkinje cells (PC) in the cerebellar cortex. IO neurons integrate their intrinsic oscillatory activity with excitatory inputs coming from the somatosensory system and inhibitory feedback coming from the cerebellar nuclei. Alongside these chemical synaptic inputs, IO neurons are coupled to one another via connexin 36 (Cx36) containing gap junctions (GJs) that create a functional syncytium between neurons. Communication between olivary neurons is regulated by these GJs and their correct functioning contributes to coherent oscillations in the IO and proper motor learning. Here, we explore the cellular pathways that can regulate the coupling between olivary neurons. We combined in vitro electrophysiology and immunohistochemistry (IHC) on mouse acute brain slices to unravel the pathways that regulate olivary coupling. We found that enhancing the activity of the protein kinase A (PKA) pathway and blocking the Ca2+/calmodulin-dependent protein kinase II (CaMKII) pathway can both down-regulate the size of the coupled network. However, these two kinases follow different mechanisms of action. Our results suggest that activation of the PKA pathway reduces the opening probability of the Cx36 GJs, whereas inhibition of the CaMKII pathway reduces the number of Cx36 GJs. The low densities of Cx36 proteins and electrical synapses in βCaMKII knock-out mice point towards an essential role for this protein kinase in regulating the density of GJs in the IO. Thus, the level of olivary coupling is a dynamic process and regulated by a variety of enzymes modulating GJs expression, docking and activity.
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Affiliation(s)
- Paolo Bazzigaluppi
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Sheena C Isenia
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Elize D Haasdijk
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Ype Elgersma
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
| | | | - Marcel T G de Jeu
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, Netherlands
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13
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Lake EMR, Bazzigaluppi P, Stefanovic B. Functional magnetic resonance imaging in chronic ischaemic stroke. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0353. [PMID: 27574307 DOI: 10.1098/rstb.2015.0353] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2016] [Indexed: 11/12/2022] Open
Abstract
Ischaemic stroke is the leading cause of adult disability worldwide. Effective rehabilitation is hindered by uncertainty surrounding the underlying mechanisms that govern long-term ischaemic injury progression. Despite its potential as a sensitive non-invasive in vivo marker of brain function that may aid in the development of new treatments, blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has found limited application in the clinical research on chronic stage stroke progression. Stroke affects each of the physiological parameters underlying the BOLD contrast, markedly complicating the interpretation of BOLD fMRI data. This review summarizes current progress on application of BOLD fMRI in the chronic stage of ischaemic injury progression and discusses means by which more information may be gained from such BOLD fMRI measurements. Concomitant measurements of vascular reactivity, neuronal activity and metabolism in preclinical models of stroke are reviewed along with illustrative examples of post-ischaemic evolution in neuronal, glial and vascular function. The realization of the BOLD fMRI potential to propel stroke research is predicated on the carefully designed preclinical research establishing an ischaemia-specific quantitative model of BOLD signal contrast to provide the framework for interpretation of fMRI findings in clinical populations.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.
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Affiliation(s)
- Evelyn M R Lake
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Paolo Bazzigaluppi
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada Fundamental Neurobiology, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada Heart and Stroke Foundation Centre for Stroke Recovery, Ottawa, Canada
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14
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Bazzigaluppi P, Ebrahim Amini A, Weisspapir I, Stefanovic B, Carlen PL. Hungry Neurons: Metabolic Insights on Seizure Dynamics. Int J Mol Sci 2017; 18:ijms18112269. [PMID: 29143800 PMCID: PMC5713239 DOI: 10.3390/ijms18112269] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 12/18/2022] Open
Abstract
Epilepsy afflicts up to 1.6% of the population and the mechanisms underlying the appearance of seizures are still not understood. In past years, many efforts have been spent trying to understand the mechanisms underlying the excessive and synchronous firing of neurons. Traditionally, attention was pointed towards synaptic (dys)function and extracellular ionic species (dys)regulation. Recently, novel clinical and preclinical studies explored the role of brain metabolism (i.e., glucose utilization) of seizures pathophysiology revealing (in most cases) reduced metabolism in the inter-ictal period and increased metabolism in the seconds preceding and during the appearance of seizures. In the present review, we summarize the clinical and preclinical observations showing metabolic dysregulation during epileptogenesis, seizure initiation, and termination, and in the inter-ictal period. Recent preclinical studies have shown that 2-Deoxyglucose (2-DG, a glycolysis blocker) is a novel therapeutic approach to reduce seizures. Furthermore, we present initial evidence for the effectiveness of 2-DG in arresting 4-Aminopyridine induced neocortical seizures in vivo in the mouse.
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Affiliation(s)
- Paolo Bazzigaluppi
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Azin Ebrahim Amini
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 3G9, Canada.
| | - Iliya Weisspapir
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Peter L Carlen
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Department of Medicine & Physiology, and Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 1A8, Canada.
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15
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Bazzigaluppi P, Beckett TL, Koletar MM, Lai AY, Joo IL, Brown ME, Carlen PL, McLaurin J, Stefanovic B. Early-stage attenuation of phase-amplitude coupling in the hippocampus and medial prefrontal cortex in a transgenic rat model of Alzheimer's disease. J Neurochem 2017; 144:669-679. [PMID: 28777881 DOI: 10.1111/jnc.14136] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/27/2017] [Accepted: 07/26/2017] [Indexed: 01/21/2023]
Abstract
Alzheimer's disease (AD) is pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration. Preclinical studies on neuronal impairments associated with progressive amyloidosis have demonstrated some Aβ-dependent neuronal dysfunction including modulation of gamma-aminobutyric acid-ergic signaling. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broad repertoire of AD-like pathologies to investigate the neuronal network functioning using simultaneous intracranial recordings from the hippocampus (HPC) and the medial prefrontal cortex (mPFC), followed by pathological analyses of gamma-aminobutyric acid (GABAA ) receptor subunits α1, α5, and δ, and glutamic acid decarboxylases (GAD65 and GAD67). Concomitant to amyloid deposition and tau hyperphosphorylation, low-gamma band power was strongly attenuated in the HPC and mPFC of TgF344-AD rats in comparison to those in non-transgenic littermates. In addition, the phase-amplitude coupling of the neuronal networks in both areas was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude in TgF344-AD animals. Finally, the gamma coherence between HPC and mPFC was attenuated as well. These results demonstrate significant neuronal network dysfunction at an early stage of AD-like pathology. This network dysfunction precedes the onset of cognitive deficits and is likely driven by Aβ and tau pathologies. This article is part of the Special Issue "Vascular Dementia".
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Affiliation(s)
- Paolo Bazzigaluppi
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario, Canada
| | - Tina L Beckett
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Margaret M Koletar
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Aaron Y Lai
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Illsung L Joo
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Mary E Brown
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario, Canada
| | - JoAnne McLaurin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Ontario, Canada
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16
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Joo IL, Lai AY, Bazzigaluppi P, Koletar MM, Dorr A, Brown ME, Thomason LAM, Sled JG, McLaurin J, Stefanovic B. Early neurovascular dysfunction in a transgenic rat model of Alzheimer's disease. Sci Rep 2017; 7:46427. [PMID: 28401931 PMCID: PMC5388880 DOI: 10.1038/srep46427] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/20/2017] [Indexed: 01/06/2023] Open
Abstract
Alzheimer's disease (AD), pathologically characterized by amyloid-β peptide (Aβ) accumulation, neurofibrillary tangle formation, and neurodegeneration, is thought to involve early-onset neurovascular abnormalities. Hitherto studies on AD-associated neurovascular injury have used animal models that exhibit only a subset of AD-like pathologies and demonstrated some Aβ-dependent vascular dysfunction and destabilization of neuronal network. The present work focuses on the early stage of disease progression and uses TgF344-AD rats that recapitulate a broader repertoire of AD-like pathologies to investigate the cerebrovascular and neuronal network functioning using in situ two-photon fluorescence microscopy and laminar array recordings of local field potentials, followed by pathological analyses of vascular wall morphology, tau hyperphosphorylation, and amyloid plaques. Concomitant to widespread amyloid deposition and tau hyperphosphorylation, cerebrovascular reactivity was strongly attenuated in cortical penetrating arterioles and venules of TgF344-AD rats in comparison to those in non-transgenic littermates. Blood flow elevation to hypercapnia was abolished in TgF344-AD rats. Concomitantly, the phase-amplitude coupling of the neuronal network was impaired, evidenced by decreased modulation of theta band phase on gamma band amplitude. These results demonstrate significant neurovascular network dysfunction at an early stage of AD-like pathology. Our study identifies early markers of pathology progression and call for development of combinatorial treatment plans.
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Affiliation(s)
- Illsung L. Joo
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Aaron Y. Lai
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Paolo Bazzigaluppi
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, 60 Leonard Avenue, Toronto, Ontario, M5T 2R1, Canada
| | - Margaret M. Koletar
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Adrienne Dorr
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Mary E. Brown
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - Lynsie A. M. Thomason
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
| | - John G. Sled
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada
| | - JoAnne McLaurin
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King’s College Circle, Toronto, Ontario, M5S 1A1, Canada
| | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, M5G 2M9, Canada
- Sunnybrook Health Sciences Center, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
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17
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Bazzigaluppi P, Weisspapir I, Stefanovic B, Leybaert L, Carlen PL. Astrocytic gap junction blockade markedly increases extracellular potassium without causing seizures in the mouse neocortex. Neurobiol Dis 2016; 101:1-7. [PMID: 28007587 DOI: 10.1016/j.nbd.2016.12.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/24/2016] [Accepted: 12/18/2016] [Indexed: 10/20/2022] Open
Abstract
Extracellular potassium concentration, [K+]o, is a major determinant of neuronal excitability. In the healthy brain, [K+]o levels are tightly controlled. During seizures, [K+]o increases up to 15mM and is thought to cause seizures due to its depolarizing effect. Although astrocytes have been suggested to play a key role in the redistribution (or spatial buffering) of excess K+ through Connexin-43 (Cx43)-based Gap Junctions (GJs), the relation between this dynamic regulatory process and seizure generation remains unknown. Here we contrasted the role of astrocytic GJs and hemichannels by studying the effect of GJ and hemichannel blockers on [K+]o regulation in vivo. [K+]o was measured by K+-sensitive microelectrodes. Neuronal excitability was estimated by local field potential (LFP) responses to forepaw stimulation and changes in the power of resting state activity. Starting at the baseline [K+]o level of 1.61±0.3mM, cortical microinjection of CBX, a broad spectrum connexin channel blocker, increased [K+]o to 11±3mM, Cx43 GJ/hemichannel blocker Gap27 increased it from 1.9±0.7 to 9±1mM. At these [K+]o levels, no seizures were observed. Cx43 hemichannel blockade with TAT-Gap19 increased [K+]o by only ~1mM. Microinjection of 4-aminopyridine, a known convulsant, increased [K+]o to ~10mM and induced spontaneously recurring seizures, whereas direct application of K+ did not trigger seizure activity. These findings are the first in vivo demonstration that astrocytic GJs are major determinants for the spatial buffering of [K+]o and that an increase in [K+]o alone does not trigger seizures in the neocortex.
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Affiliation(s)
- Paolo Bazzigaluppi
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada.
| | - Iliya Weisspapir
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Ontario, Canada
| | - Luc Leybaert
- Department of Basic Medical Sciences, University of Ghent, 9000 Ghent, Belgium
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
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18
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Lake EM, Mester J, Thomason LAM, Adams C, Bazzigaluppi P, Koletar M, Janik R, Carlen P, McLaurin J, Stanisz GJ, Stefanovic B. Modulation of the peri-infarct neurogliovascular function by delayed COX-1 inhibition. J Magn Reson Imaging 2016; 46:505-517. [DOI: 10.1002/jmri.25541] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 10/20/2016] [Indexed: 11/06/2022] Open
Affiliation(s)
- Evelyn M.R. Lake
- Department of Radiology and Biomedical Imaging; Yale University; New Haven Connecticut USA
- Department of Medical Biophysics; University of Toronto; Ontario Canada
| | - James Mester
- Department of Medical Biophysics; University of Toronto; Ontario Canada
| | - Lynsie AM Thomason
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
| | - Conner Adams
- Department of Medical Biophysics; University of Toronto; Ontario Canada
| | - Paolo Bazzigaluppi
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
- Fundamental Neurobiology, Toronto Western Research Institute; Toronto Ontario Canada
| | - Margaret Koletar
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
| | - Rafal Janik
- Department of Medical Biophysics; University of Toronto; Ontario Canada
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
| | - Peter Carlen
- Fundamental Neurobiology, Toronto Western Research Institute; Toronto Ontario Canada
| | - JoAnne McLaurin
- Biological Science, Sunnybrook Research Institute; Toronto Ontario Canada
- Department of Laboratory Medicine and Pathobiology; University of Toronto; Ontario Canada
- Heart and Stroke Foundation Canadian Partnership for Stroke Recovery; Ottawa Ontario Canada
| | - Greg J Stanisz
- Department of Medical Biophysics; University of Toronto; Ontario Canada
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
- Department of Neurosurgery and Pediatric Neurosurgery; Medical University; Lublin Poland
| | - Bojana Stefanovic
- Department of Medical Biophysics; University of Toronto; Ontario Canada
- Physical Sciences, Sunnybrook Research Institute; Toronto Ontario Canada
- Heart and Stroke Foundation Canadian Partnership for Stroke Recovery; Ottawa Ontario Canada
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19
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Bazzigaluppi P, de Jeu MTG. Heterogeneous Expression of T-type Ca(2+) Channels Defines Different Neuronal Populations in the Inferior Olive of the Mouse. Front Cell Neurosci 2016; 10:192. [PMID: 27540355 PMCID: PMC4972830 DOI: 10.3389/fncel.2016.00192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 07/19/2016] [Indexed: 11/17/2022] Open
Abstract
The neurons in the inferior olive express subthreshold oscillations in their membrane potential. This oscillatory activity is known to drive synchronous activity in the cerebellar cortex and plays a role in motor learning and motor timing. In the past years, it was commonly thought that olivary neurons belonged to a unique population of oscillating units and that oscillation properties were exclusively dependent on network settings and/or synaptic inputs. The origin of olivary oscillations is now known to be a local phenomenon and is generated by a combination of conductances. In the present work, we show the existence of at least two neuronal populations that can be distinguished on the basis of the presence or absence of low-voltage activated Ca2+ channels. The expression of this channel determines the oscillatory behavior of olivary neurons. Furthermore, the number of cells that express this channel is different between sub nuclei of the inferior olive. These findings clearly indicate the functional variability within and between olivary sub nuclei.
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Affiliation(s)
- Paolo Bazzigaluppi
- Department of Neuroscience, Erasmus Medical Center Rotterdam, Netherlands
| | - Marcel T G de Jeu
- Department of Neuroscience, Erasmus Medical Center Rotterdam, Netherlands
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Bazzigaluppi P, Dufour S, Carlen PL. Wide field fluorescent imaging of extracellular spatiotemporal potassium dynamics in vivo. Neuroimage 2014; 104:110-6. [PMID: 25312775 DOI: 10.1016/j.neuroimage.2014.10.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/03/2014] [Accepted: 10/04/2014] [Indexed: 11/18/2022] Open
Abstract
Potassium homeostasis is fundamental for the physiological functioning of the brain. Increased [K(+)] in the extracellular fluid has a major impact on neuronal physiology and can lead to ictal events. Compromised regulation of extracellular [K(+)] is involved in generation of seizures in animal models and potentially also in humans. For this reason, the investigation of K(+) spatio-temporal dynamics is of fundamental importance for neuroscientists in the field of epilepsy and other related pathologies. To date, the majority of studies investigating changes in extracellular K(+) have been conducted using a micropipette filled with a K(+) sensitive solution. However, this approach presents a major limitation: the area of the measurement is circumscribed to the tip of the pipette and it is not possible to know the spatiotemporal distribution or origin of the focally measured K(+) signal. Here we propose a novel approach, based on wide field fluorescence, to measure extracellular K(+) dynamics in neural tissue. Recording the local field potential from the somatosensory cortex of the mouse, we compared responses obtained from a K(+)-sensitive microelectrode to the spatiotemporal increases in fluorescence of the fluorophore, Asante Potassium Green-2, in physiological conditions and during 4-AP induced ictal activity. We conclude that wide field imaging is a valuable and versatile tool to measure K(+) dynamics over a large area of the cerebral cortex and is capable of capturing fast dynamics such as during ictal events. Moreover, the present technique is potentially adaptable to address questions regarding spatiotemporal dynamics of other ionic species.
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Affiliation(s)
- Paolo Bazzigaluppi
- Toronto Western Research Institute, Toronto, Canada; Sunnybrook Research Center, Toronto, Canada.
| | - Suzie Dufour
- Toronto Western Research Institute, Toronto, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Peter L Carlen
- Toronto Western Research Institute, Toronto, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
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Abstract
The inferior olive (IO) forms one of the major gateways for information that travels to the cerebellar cortex. Olivary neurons process sensory and motor signals that are subsequently relayed to Purkinje cells. The intrinsic subthreshold membrane potential oscillations of the olivary neurons are thought to be important for gating this flow of information. In vitro studies have revealed that the phase of the subthreshold oscillation determines the size of the olivary burst and may gate the information flow or encode the temporal state of the olivary network. Here, we investigated whether the same phenomenon occurred in murine olivary cells in an intact olivocerebellar system using the in vivo whole-cell recording technique. Our in vivo findings revealed that the number of wavelets within the olivary burst did not encode the timing of the spike relative to the phase of the oscillation but was related to the amplitude of the oscillation. Manipulating the oscillation amplitude by applying Harmaline confirmed the inverse relationship between the amplitude of oscillation and the number of wavelets within the olivary burst. Furthermore, we demonstrated that electrotonic coupling between olivary neurons affect this modulation of the olivary burst size. Based on these results, we suggest that the olivary burst size might reflect the “expectancy” of a spike to occur rather than the spike timing, and that this process requires the presence of gap junction coupling.
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Affiliation(s)
- Paolo Bazzigaluppi
- Department of Neuroscience, Erasmus Medical Center Rotterdam, Netherlands
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