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Christensen J, Wright DK, Yamakawa GR, Shultz SR, Mychasiuk R. Repetitive Mild Traumatic Brain Injury Alters Glymphatic Clearance Rates in Limbic Structures of Adolescent Female Rats. Sci Rep 2020; 10:6254. [PMID: 32277097 PMCID: PMC7148360 DOI: 10.1038/s41598-020-63022-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/22/2020] [Indexed: 01/02/2023] Open
Abstract
The glymphatic system is the macroscopic waste clearance system for the central nervous system. Glymphatic dysfunction has been linked to several neurological conditions, including traumatic brain injury (TBI). Adolescents are at particularly high risk for experiencing a TBI, particularly mild TBI (mTBI) and repetitive mTBI (RmTBI); however, glymphatic clearance, and how it relates to behavioral outcomes, has not been investigated in this context. Therefore, this study examined glymphatic function in the adolescent brain following RmTBI. Female adolescent Sprague Dawley rats were subjected to either three mTBIs or sham injuries spaced three days apart. One-day after their final injury, the animals underwent a beam walking task to assess sensorimotor function, and contrast-enhanced MRI to visualize glymphatic clearance rate. Behavioural measures indicated that the RmTBI group displayed an increase in loss of consciousness as well as motor coordination and balance deficits consistent with our previous studies. The contrast-enhanced MRI results indicated that the female adolescent glymphatic system responds to RmTBI in a region-specific manner, wherein an increased influx but reduced efflux was observed throughout limbic structures (hypothalamus, hippocampus, and amygdala) and the olfactory bulb but neither the influx or efflux were altered in the cortical structures (primary motor cortex, insular cortex, and dorsolateral prefrontal cortex) examined. This may indicate a role for an impaired and/or inefficient glymphatic system in the limbic structures and cortical structures, respectively, in the development of post-concussive symptomology during adolescence.
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Affiliation(s)
- Jennaya Christensen
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - David K Wright
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Glenn R Yamakawa
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Sandy R Shultz
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
| | - Richelle Mychasiuk
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia.
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
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