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Xiong G, Metheny H, Hood K, Jean I, Farrugia AM, Johnson BN, Tummala SR, Cohen NA, Cohen AS. Detection and verification of neurodegeneration after traumatic brain injury in the mouse: Immunohistochemical staining for amyloid precursor protein. Brain Pathol 2023; 33:e13163. [PMID: 37156643 PMCID: PMC10580020 DOI: 10.1111/bpa.13163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 04/18/2023] [Indexed: 05/10/2023] Open
Abstract
Previous studies of human traumatic brain injury (TBI) have shown diffuse axonal injury as varicosities or spheroids in white matter (WM) bundles when using immunoperoxidase-ABC staining with 22C11, a mouse monoclonal antibody against amyloid precursor protein (APP). These findings have been interpreted as TBI-induced axonal pathology. In a mouse model of TBI however, when we used immunofluorescent staining with 22C11, as opposed to immunoperoxidase staining, we did not observe varicosities or spheroids. To explore this discrepancy, we performed immunofluorescent staining with Y188, an APP knockout-validated rabbit monoclonal that shows baseline immunoreactivity in neurons and oligodendrocytes of non-injured mice, with some arranged-like varicosities. In gray matter after injury, Y188 intensely stained axonal blebs. In WM, we encountered large patches of heavily stained puncta, heterogeneous in size. Scattered axonal blebs were also identified among these Y188-stained puncta. To assess the neuronal origin of Y188 staining after TBI we made use of transgenic mice with fluorescently labeled neurons and axons. A close correlation was observed between Y188-stained axonal blebs and fluorescently labeled neuronal cell bodies/axons. By contrast, no correlation was observed between Y188-stained puncta and fluorescent axons in WM, suggesting that these puncta in WM did not originate from axons, and casting further doubt on the nature of previous reports with 22C11. As such, we strongly recommend Y188 as a biomarker for detecting damaged neurons and axons after TBI. With Y188, stained axonal blebs likely represent acute axonal truncations that may lead to death of the parent neurons. Y188-stained puncta in WM may indicate damaged oligodendrocytes, whose death and clearance can result in secondary demyelination and Wallerian degeneration of axons. We also provide evidence suggesting that 22C11-stained varicosities or spheroids previously reported in TBI patients might be showing damaged oligodendrocytes, due to a cross-reaction between the ABC kit and upregulated endogenous biotin.
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Affiliation(s)
- Guoxiang Xiong
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Hannah Metheny
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Kaitlin Hood
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Neuroscience Graduate GroupUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Ian Jean
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Anthony M. Farrugia
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Brian N. Johnson
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Shanti R. Tummala
- Department of Bioengineering, School of Engineering and Applied SciencesUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Noam A. Cohen
- Philadelphia Veterans Affairs Medical CenterPhiladelphiaPennsylvaniaUSA
- Department of Otorhinolaryngology–Head and Neck SurgeryPerelman School of Medicine, University of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | - Akiva S. Cohen
- Department of Anesthesiology and Critical Care MedicineThe Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
- Department of Anesthesiology and Critical Care Medicine, Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
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Ramos-Llordén G, Park D, Kirsch JE, Scholz A, Keil B, Maffei C, Lee HH, Bilgiç B, Edlow BL, Mekkaoui C, Yendiki A, Witzel T, Huang SY. Eddy current-induced artifacts correction in high gradient strength diffusion MRI with dynamic field monitoring: demonstration in ex vivo human brain imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528684. [PMID: 36824894 PMCID: PMC9948962 DOI: 10.1101/2023.02.15.528684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Purpose To demonstrate the advantages of spatiotemporal magnetic field monitoring to correct eddy current-induced artifacts (ghosting and geometric distortions) in high gradient strength diffusion MRI (dMRI). Methods A dynamic field camera with 16 NMR field probes was used to characterize eddy current fields induced from diffusion gradients for different gradients strengths (up to 300 mT/m), diffusion directions, and shots in a 3D multi-shot EPI sequence on a 3T Connectom scanner. The efficacy of dynamic field monitoring-based image reconstruction was demonstrated on high-resolution whole brain ex vivo dMRI. A 3D multi-shot image reconstruction framework was informed with the actual nonlinear phase evolution measured with the dynamic field camera, thereby accounting for high-order eddy currents fields on top of the image encoding gradients in the image formation model. Results Eddy current fields from diffusion gradients at high gradient strength in a 3T Connectom scanner are highly nonlinear in space and time, inducing high-order spatial phase modulations between odd/even echoes and shots that are not static during the readout. Superior reduction of ghosting and geometric distortion was achieved with dynamic field monitoring compared to ghosting approaches such as navigator- and structured low-rank-based methods or MUSE, followed by image-based distortion correction with eddy. Improved dMRI analysis is demonstrated with diffusion tensor imaging and high-angular resolution diffusion imaging. Conclusion Strong eddy current artifacts characteristic of high gradient strength dMRI can be well corrected with dynamic field monitoring-based image reconstruction, unlike the two-step approach consisting of ghosting correction followed by geometric distortion reduction with eddy.
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Chen Q, Chen X, Xu L, Zhang R, Li Z, Yue X, Qiao D. Traumatic axonal injury: neuropathological features, postmortem diagnostic methods, and strategies. Forensic Sci Med Pathol 2022; 18:530-544. [PMID: 36117238 DOI: 10.1007/s12024-022-00522-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2022] [Indexed: 12/14/2022]
Abstract
Traumatic brain injury (TBI) has high morbidity and poor prognosis and imposes a serious socioeconomic burden. Traumatic axonal injury (TAI), which is one of the common pathological changes in the primary injury of TBI, is often caused by the external force to the head that causes the white matter bundles to generate shear stress and tension; resulting in tissue damage and leading to the cytoskeletal disorder. At present, the forensic pathological diagnosis of TAI-caused death is still a difficult problem. Most of the TAI biomarkers studied are used for the prediction, evaluation, and prognosis of TAI in the living state. The research subjects are mainly humans in the living state or model animals, which are not suitable for the postmortem diagnosis of TAI. In addition, there is still a lack of recognized indicators for the autopsy pathological diagnosis of TAI. Different diagnostic methods and markers have their limitations, and there is a lack of systematic research and summary of autopsy diagnostic markers of TAI. Therefore, this study mainly summarizes the pathological mechanism, common methods, techniques of postmortem diagnosis, and corresponding biomarkers of TAI, and puts forward the strategies for postmortem diagnosis of TAI for forensic cases with different survival times, which is of great significance to forensic pathological diagnosis.
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Affiliation(s)
- Qianling Chen
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China
| | - Xuebing Chen
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China
| | - Luyao Xu
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China
| | - Rui Zhang
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China
| | - Zhigang Li
- Guangzhou Forensic Science Institute & Key Laboratory of Forensic Pathology, Ministry of Public Security, Guangzhou, 510442, China.
| | - Xia Yue
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China.
| | - Dongfang Qiao
- School of Forensic Medicine, Southern Medical University, South Shaitai Road #1023, Guangzhou, 510515, Guangdong, China.
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4
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Edlow BL, Bodien YG, Baxter T, Belanger H, Cali R, Deary K, Fischl B, Foulkes AS, Gilmore N, Greve DN, Hooker JM, Huang SY, Kelemen JN, Kimberly WT, Maffei C, Masood M, Perl D, Polimeni JR, Rosen BR, Tromly S, Tseng CEJ, Yao EF, Zurcher NR, Mac Donald CL, Dams-O'Connor K. Long-Term Effects of Repeated Blast Exposure in United States Special Operations Forces Personnel: A Pilot Study Protocol. J Neurotrauma 2022; 39:1391-1407. [PMID: 35620901 PMCID: PMC9529318 DOI: 10.1089/neu.2022.0030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Emerging evidence suggests that repeated blast exposure (RBE) is associated with brain injury in military personnel. United States (U.S.) Special Operations Forces (SOF) personnel experience high rates of blast exposure during training and combat, but the effects of low-level RBE on brain structure and function in SOF have not been comprehensively characterized. Further, the pathophysiological link between RBE-related brain injuries and cognitive, behavioral, and physical symptoms has not been fully elucidated. We present a protocol for an observational pilot study, Long-Term Effects of Repeated Blast Exposure in U.S. SOF Personnel (ReBlast). In this exploratory study, 30 active-duty SOF personnel with RBE will participate in a comprehensive evaluation of: 1) brain network structure and function using Connectome magnetic resonance imaging (MRI) and 7 Tesla MRI; 2) neuroinflammation and tau deposition using positron emission tomography; 3) blood proteomics and metabolomics; 4) behavioral and physical symptoms using self-report measures; and 5) cognition using a battery of conventional and digitized assessments designed to detect subtle deficits in otherwise high-performing individuals. We will identify clinical, neuroimaging, and blood-based phenotypes that are associated with level of RBE, as measured by the Generalized Blast Exposure Value. Candidate biomarkers of RBE-related brain injury will inform the design of a subsequent study that will test a diagnostic assessment battery for detecting RBE-related brain injury. Ultimately, we anticipate that the ReBlast study will facilitate the development of interventions to optimize the brain health, quality of life, and battle readiness of U.S. SOF personnel.
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Affiliation(s)
- Brian L Edlow
- Harvard Medical School, 1811, 175 Cambridge Street - Suite 300, Boston, Massachusetts, United States, 02115.,Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Yelena G Bodien
- Massachusetts General Hospital, 2348, Department of Neurology, 101 Merrimac, Boston, Massachusetts, United States, 02114;
| | - Timothy Baxter
- University of South Florida, 7831, Institute for Applied Engineering, Tampa, Florida, United States;
| | - Heather Belanger
- University of South Florida, 7831, Department of Psychiatry and Behavioral Neurosciences, Tampa, Florida, United States;
| | - Ryan Cali
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - Katryna Deary
- Navy SEAL Foundation, Virginia Beach, Virginia, United States;
| | - Bruce Fischl
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Room 2301, 149 13th Street, Charlestown, Massachusetts, United States, 02129-2020.,Massachusetts General Hospital;
| | - Andrea S Foulkes
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - Natalie Gilmore
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - Douglas N Greve
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Jacob M Hooker
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Susie Y Huang
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Jessica N Kelemen
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - W Taylor Kimberly
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - Chiara Maffei
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Maryam Masood
- Massachusetts General Hospital, 2348, Boston, Massachusetts, United States;
| | - Daniel Perl
- Uniformed Services University of the Health Sciences, 1685, Pathology, 4301 Jones Bridge Road, Room B3138, Bethesda, Maryland, United States, 20814;
| | - Jonathan R Polimeni
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Bruce R Rosen
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Charlestown, Massachusetts, United States;
| | - Samantha Tromly
- University of South Florida, 7831, Institute for Applied Engineering, Tampa, Florida, United States;
| | - Chieh-En J Tseng
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Eveline F Yao
- United States Special Operations Command, Office of the Surgeon General, MacDill Air Force Base, United States;
| | - Nicole R Zurcher
- Massachusetts General Hospital, 2348, Athinoula A. Martinos Center for Biomedical Imaging, Boston, Massachusetts, United States;
| | - Christine L Mac Donald
- University of Washington, 7284, Department of Neurological Surgery, Seattle, Washington, United States;
| | - Kristen Dams-O'Connor
- Icahn School of Medicine at Mount Sinai, 5925, Rehabilitation Medicine, One Gustave Levy Place, Box 1163, New York, New York, United States, 10029; kristen.dams-o'
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Charvet CJ, Ofori K, Baucum C, Sun J, Modrell MS, Hekmatyar K, Edlow BL, van der Kouwe AJ. Tracing Modification to Cortical Circuits in Human and Nonhuman Primates from High-Resolution Tractography, Transcription, and Temporal Dimensions. J Neurosci 2022; 42:3749-3767. [PMID: 35332086 PMCID: PMC9087811 DOI: 10.1523/jneurosci.1506-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 03/11/2022] [Accepted: 03/15/2022] [Indexed: 11/21/2022] Open
Abstract
The neural circuits that support human cognition are a topic of enduring interest. Yet, there are limited tools available to map brain circuits in the human and nonhuman primate brain. We harnessed high-resolution diffusion MR tractography, anatomic, and transcriptomic data from individuals of either sex to investigate the evolution and development of frontal cortex circuitry. We applied machine learning to RNA sequencing data to find corresponding ages between humans and macaques and to compare the development of circuits across species. We transcriptionally defined neural circuits by testing for associations between gene expression and white matter maturation. We then considered transcriptional and structural growth to test whether frontal cortex circuit maturation is unusually extended in humans relative to other species. We also considered gene expression and high-resolution diffusion MR tractography of adult brains to test for cross-species variation in frontal cortex circuits. We found that frontal cortex circuitry development is extended in primates, and concomitant with an expansion in corticocortical pathways compared with mice in adulthood. Importantly, we found that these parameters varied relatively little across humans and studied primates. These data identify a surprising collection of conserved features in frontal cortex circuits across humans and Old World monkeys. Our work demonstrates that integrating transcriptional and structural data across temporal dimensions is a robust approach to trace the evolution of brain pathways in primates.SIGNIFICANCE STATEMENT Diffusion MR tractography is an exciting method to explore pathways, but there are uncertainties in the accuracy of reconstructed tracts. We broaden the repertoire of toolkits to enhance our ability to trace human brain pathways from diffusion MR tractography. Our integrative approach finds corresponding ages across species and transcriptionally defines neural circuits. We used this information to test for variation in circuit maturation across species and found a surprising constellation of similar features in frontal cortex neural circuits across humans and primates. Integrating across scales of biological organization expands the repertoire of tools available to study pathways in primates, which opens new avenues to study pathways in health and diseases of the human brain.
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Affiliation(s)
- Christine J Charvet
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5518
- Delaware Center for Neuroscience, Delaware State University, Dover, Delaware 19901
| | - Kwadwo Ofori
- PhD Program in Neuroscience, Department in Biology, Delaware State University, Dover, Delaware 19901
| | - Christine Baucum
- Department of Biology, Bath Spa University, Bath BA2 9BN, United Kingdom
| | - Jianli Sun
- Delaware Center for Neuroscience, Delaware State University, Dover, Delaware 19901
| | - Melinda S Modrell
- Delaware Center for Neuroscience, Delaware State University, Dover, Delaware 19901
| | - Khan Hekmatyar
- Center for Biomedical and Brain Imaging Center, University of Delaware, Wilmington, Delaware 19716
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts 02114
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129
| | - Andre J van der Kouwe
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, Massachusetts 02129
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Dopaminergic modulation of human consciousness via default mode network connectivity. Proc Natl Acad Sci U S A 2021; 118:2111268118. [PMID: 34330840 DOI: 10.1073/pnas.2111268118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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7
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Bianciardi M, Izzy S, Rosen BR, Wald LL, Edlow BL. Location of Subcortical Microbleeds and Recovery of Consciousness After Severe Traumatic Brain Injury. Neurology 2021; 97:e113-e123. [PMID: 34050005 PMCID: PMC8279563 DOI: 10.1212/wnl.0000000000012192] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/09/2021] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND In patients with severe traumatic brain injury (TBI), coma is associated with impaired subcortical arousal mechanisms. However, it is unknown which nuclei involved in arousal (arousal nuclei) are implicated in coma pathogenesis and are compatible with coma recovery. METHODS We mapped an atlas of arousal nuclei in the brainstem, thalamus, hypothalamus, and basal forebrain onto 3 tesla susceptibility-weighted images (SWI) in 12 patients with acute severe TBI who presented in coma and recovered consciousness within 6 months. We assessed the spatial distribution and volume of SWI microbleeds and evaluated the association of microbleed volume with the duration of unresponsiveness and functional recovery at 6 months. RESULTS There was no single arousal nucleus affected by microbleeds in all patients. Rather, multiple combinations of microbleeds in brainstem, thalamic, and hypothalamic arousal nuclei were associated with coma and were compatible with recovery of consciousness. Microbleeds were frequently detected in the midbrain (100%), thalamus (83%), and pons (75%). Within the brainstem, the microbleed incidence was largest within the mesopontine tegmentum (e.g., pedunculotegmental nucleus, mesencephalic reticular formation) and ventral midbrain (e.g., substantia nigra, ventral tegmental area). Brainstem arousal nuclei were partially affected by microbleeds, with microbleed volume not exceeding 35% of brainstem nucleus volume on average. Compared to microbleed volume within nonarousal brainstem regions, the microbleed volume within arousal brainstem nuclei accounted for a larger proportion of variance in the duration of unresponsiveness and 6-month Glasgow Outcome Scale-Extended scores. CONCLUSION These results suggest resilience of arousal mechanisms in the human brain after severe TBI.
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Affiliation(s)
- Marta Bianciardi
- From the Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging (M.B., B.R.R., L.L.W., B.L.E.), and Center for Neurotechnology and Neurorecovery, Department of Neurology (B.L.E.), Massachusetts General Hospital and Harvard Medical School; Division of Sleep Medicine (M.B.), Harvard University; and Department of Neurology (S.I.), Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
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Bradshaw DV, Knutsen AK, Korotcov A, Sullivan GM, Radomski KL, Dardzinski BJ, Zi X, McDaniel DP, Armstrong RC. Genetic inactivation of SARM1 axon degeneration pathway improves outcome trajectory after experimental traumatic brain injury based on pathological, radiological, and functional measures. Acta Neuropathol Commun 2021; 9:89. [PMID: 34001261 PMCID: PMC8130449 DOI: 10.1186/s40478-021-01193-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023] Open
Abstract
Traumatic brain injury (TBI) causes chronic symptoms and increased risk of neurodegeneration. Axons in white matter tracts, such as the corpus callosum (CC), are critical components of neural circuits and particularly vulnerable to TBI. Treatments are needed to protect axons from traumatic injury and mitigate post-traumatic neurodegeneration. SARM1 protein is a central driver of axon degeneration through a conserved molecular pathway. Sarm1−/− mice with knockout (KO) of the Sarm1 gene enable genetic proof-of-concept testing of the SARM1 pathway as a therapeutic target. We evaluated Sarm1 deletion effects after TBI using a concussive model that causes traumatic axonal injury and progresses to CC atrophy at 10 weeks, indicating post-traumatic neurodegeneration. Sarm1 wild-type (WT) mice developed significant CC atrophy that was reduced in Sarm1 KO mice. Ultrastructural classification of pathology of individual axons, using electron microscopy, demonstrated that Sarm1 KO preserved more intact axons and reduced damaged or demyelinated axons. Longitudinal MRI studies in live mice identified significantly reduced CC volume after TBI in Sarm1 WT mice that was attenuated in Sarm1 KO mice. MR diffusion tensor imaging detected reduced fractional anisotropy in both genotypes while axial diffusivity remained higher in Sarm1 KO mice. Immunohistochemistry revealed significant attenuation of CC atrophy, myelin loss, and neuroinflammation in Sarm1 KO mice after TBI. Functionally, Sarm1 KO mice exhibited beneficial effects in motor learning and sleep behavior. Based on these findings, Sarm1 inactivation can protect axons and white matter tracts to improve translational outcomes associated with CC atrophy and post-traumatic neurodegeneration.
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