1
|
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.
Collapse
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
| |
Collapse
|
2
|
Joo IL, Lam WW, Oakden W, Hill ME, Koletar MM, Morrone CD, Stanisz GJ, McLaurin J, Stefanovic B. Early alterations in brain glucose metabolism and vascular function in a transgenic rat model of Alzheimer's disease. Prog Neurobiol 2022; 217:102327. [PMID: 35870681 DOI: 10.1016/j.pneurobio.2022.102327] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 05/06/2022] [Accepted: 07/18/2022] [Indexed: 11/28/2022]
Abstract
Alteration in brain metabolism predates clinical onset of Alzheimer's Disease (AD). Realizing its potential as an early diagnostic marker, however, requires understanding how early AD metabolic dysregulation manifests on non-invasive brain imaging. We presently utilized magnetic resonance imaging and spectroscopy to map glucose and ketone metabolic profiles and image cerebrovascular function in a rat model of early stage AD - 9-month-old TgF344-AD (TgAD) rats - and their age-matched non-transgenic (nTg) littermates. Compared to the nTg rats, TgAD rats displayed attenuation in global cerebral and hippocampal vasoreactivity to hypercapnia, by 49±17% and 58±19%, respectively, while their functional hyperemia to somatosensory stimulation diminished by 69±5%. To assess brain glucose uptake, rats were fasted overnight and then challenged with an intravenous infusion of 2-deoxy-D-glucose (2DG). Compared to their non-transgenic littermates, TgAD rats exhibited 99±10% and 52±5% smaller glucose uptake in the entorhinal cortex and the hippocampus, respectively. Moreover, hippocampal glucose uptake reduction in male TgAD rats compared to the nTg was 54±36% greater than the reduction seen in female TgAD rats. TgAD rats also showed a 59±42% increase in total choline level in the hippocampus, suggesting increased membrane turnover. In combination with our earlier findings of impaired electrophysiological metrics at this early stage of AD pathology progression, our findings suggest that subtle neuronal function alterations that would be difficult to assess in a clinical population may be accompanied by MRI-detectable changes in brain glucose metabolism and cerebrovascular function.
Collapse
Affiliation(s)
- Illsung L Joo
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada.
| | - Wilfred W Lam
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada.
| | - Wendy Oakden
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada.
| | - Mary E Hill
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada.
| | - Margaret M Koletar
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada.
| | - Christopher D Morrone
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada; Department of Laboratory Medicine and Pathology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Greg J Stanisz
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada; Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1L7, Canada.
| | - JoAnne McLaurin
- Biological Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada; Department of Laboratory Medicine and Pathology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, Toronto, ON M4N 3N5, Canada; Department of Medical Biophysics, Faculty of Medicine, University of Toronto, Toronto, ON M5G 1L7, Canada.
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Al‐Azzawi ZA, Joo IL, Koletar MM, Hill ME, Mester JR, Stefanovic B, McLaurin J. Awake two‐photon fluorescence imaging in the TgF344‐AD Alzheimer’s disease rat model. Alzheimers Dement 2020. [DOI: 10.1002/alz.043444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zaid A.M. Al‐Azzawi
- Sunnybrook Research Institute Toronto ON Canada
- University of Toronto Toronto ON Canada
| | | | | | | | - James R. Mester
- Sunnybrook Research Institute Toronto ON Canada
- University of Toronto Toronto ON Canada
| | - Bojana Stefanovic
- Sunnybrook Research Institute Toronto ON Canada
- University of Toronto Toronto ON Canada
| | - JoAnne McLaurin
- Sunnybrook Research Institute Toronto ON Canada
- University of Toronto Toronto ON Canada
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
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".
Collapse
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
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Dorr A, Thomason LA, Koletar MM, Joo IL, Steinman J, Cahill LS, Sled JG, Stefanovic B. Effects of voluntary exercise on structure and function of cortical microvasculature. J Cereb Blood Flow Metab 2017; 37:1046-1059. [PMID: 27683451 PMCID: PMC5363487 DOI: 10.1177/0271678x16669514] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aerobic activity has been shown highly beneficial to brain health, yet much uncertainty still surrounds the effects of exercise on the functioning of cerebral microvasculature. This study used two-photon fluorescence microscopy to examine cerebral hemodynamic alterations as well as accompanying geometric changes in the cortical microvascular network following five weeks of voluntary exercise in transgenic mice endogenously expressing tdTomato in vascular endothelial cells to allow visualization of microvessels irrespective of their perfusion levels. We found a diminished microvascular response to a hypercapnic challenge (10% FiCO2) in running mice when compared to that in nonrunning controls despite commensurate increases in transcutaneous CO2 tension. The flow increase to hypercapnia in runners was 70% lower than that in nonrunners (p = 0.0070) and the runners' arteriolar red blood cell speed changed by only half the amount seen in nonrunners (p = 0.0085). No changes were seen in resting hemodynamics or in the systemic physiological parameters measured. Although a few unperfused new vessels were observed on visual inspection, running did not produce significant morphological differences in the microvascular morphometric parameters, quantified following semiautomated tracking of the microvascular networks. We propose that voluntary running led to increased cortical microvascular efficiency and desensitization to CO2 elevation.
Collapse
Affiliation(s)
| | | | | | - Illsung L Joo
- 1 Sunnybrook Research Institute, Toronto, Canada.,2 Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Joe Steinman
- 2 Department of Medical Biophysics, University of Toronto, Toronto, Canada.,3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - Lindsay S Cahill
- 3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - John G Sled
- 2 Department of Medical Biophysics, University of Toronto, Toronto, Canada.,3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - Bojana Stefanovic
- 1 Sunnybrook Research Institute, Toronto, Canada.,2 Department of Medical Biophysics, University of Toronto, Toronto, Canada
| |
Collapse
|