This amended application seeks to explore a relatively unchartered area in the pathobiology of traumatic brain injury (TBI) focusing on those injuries involving diffuse damage to the brain. Unlike the majority of contemporary TBI literature which focuses on focal change, most of which entails large destructive lesions such as contusion and hematoma formation, this application explores the potential that diffuse TBI, not complicated by focal lesions or secondary insult, evokes diffuse changes in either the neuronal somatic plasma membrane or perisomatic axonal appendages. Specifically, we posit that the forces of injury are capable of mechanically porating the intact plasma membrane causing either enduring or transient membrane perturbations that can respectively participate in progressive damage leading to cell death or membrane resealing and cell recovery. The same forces of injury are also envisioned to evoke, in other populations of neurons, perisomatic axotomy. It is posited that this TBI-induced damage translates into neuronal somatic perturbation. However, in contrast to published literature, we posit that most neurons do not die. Rather they undergo a reparative attempt. These premises will be explored in two well characterized models of TBI, fluid percussion and impact acceleration TBI. The potential for plasma membrane poration and resealing will be assessed via different molecular in weight/size tracers administered intrathecally at various time points pre and post injury. Companion quantitative studies using the principles of modern stereology will assess the numbers of neurons involved in this complex pathobiology within specific domains of the neocortex. Parallel LM immunocytochemical and ultrastructural analyses will provide for the direct assessment of membrane integrity and related cytoskeletal, organelle or nuclear changes that correlate either with cell recovery or a progression of damage leading to death. Intrathecal tracers will be used in those neurons sustaining perisomatic axotomy to exclude the potential for plasma membrane potation, while using parallel immunocytochemical approaches to understand if such axotomized neurons progress to cell death or rather undergo transient perturbation with reorganization and repair. Collectively, these studies should reshape our appreciation of the complex pathobiology of TBI.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS045824-05
Application #
7237898
Study Section
Brain Disorders and Clinical Neuroscience 5 (BDCN)
Program Officer
Hicks, Ramona R
Project Start
2003-09-30
Project End
2009-08-04
Budget Start
2007-06-01
Budget End
2009-08-04
Support Year
5
Fiscal Year
2007
Total Cost
$328,902
Indirect Cost
Name
Virginia Commonwealth University
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
105300446
City
Richmond
State
VA
Country
United States
Zip Code
23298
Lafrenaye, Audrey D; Krahe, Thomas E; Povlishock, John T (2014) Moderately elevated intracranial pressure after diffuse traumatic brain injury is associated with exacerbated neuronal pathology and behavioral morbidity in the rat. J Cereb Blood Flow Metab 34:1628-36
Lafrenaye, Audrey D; McGinn, Melissa J; Povlishock, John T (2012) Increased intracranial pressure after diffuse traumatic brain injury exacerbates neuronal somatic membrane poration but not axonal injury: evidence for primary intracranial pressure-induced neuronal perturbation. J Cereb Blood Flow Metab 32:1919-32
Greer, John E; McGinn, Melissa J; Povlishock, John T (2011) Diffuse traumatic axonal injury in the mouse induces atrophy, c-Jun activation, and axonal outgrowth in the axotomized neuronal population. J Neurosci 31:5089-105
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Singleton, Richard H; Povlishock, John T (2004) Identification and characterization of heterogeneous neuronal injury and death in regions of diffuse brain injury: evidence for multiple independent injury phenotypes. J Neurosci 24:3543-53