title: Glutamate Neurotransmission in Rodent Models of Traumatic Brain Injury.
abstract: Traumatic brain injury (TBI) is a leading cause of death and disability in people younger than 45 and is a significant public health concern. In addition to primary mechanical damage to cells and tissue, TBI involves additional molecular mechanisms of injury, termed secondary injury, that continue to evolve over hours, days, weeks, and beyond. The trajectory of recovery after TBI is highly unpredictable and in many cases results in chronic cognitive and behavioral changes. Acutely after TBI, there is an unregulated release of glutamate that cannot be buffered or cleared effectively, resulting in damaging levels of glutamate in the extracellular space. This initial loss of glutamate homeostasis may initiate additional changes in glutamate regulation. The excitatory amino acid transporters (EAATs) are expressed on both neurons and glia and are the principal mechanism for maintaining extracellular glutamate levels. Diffusion of glutamate outside the synapse due to impaired uptake may lead to increased extrasynaptic glutamate signaling, secondary injury through activation of cell death pathways, and loss of fidelity and specificity of synaptic transmission. Coordination of glutamate release and uptake is critical to regulating synaptic strength, long-term potentiation and depression, and cognitive processes. In this review, we will discuss dysregulation of extracellular glutamate and glutamate uptake in the acute stage of TBI and how failure to resolve acute disruptions in glutamate homeostatic mechanisms may play a causal role in chronic cognitive symptoms after TBI.
authors.affiliation: 1 Biological and Biomedical Sciences Doctoral Program, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Dorsett
authors.affiliation: 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: McGuire
authors.affiliation: 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio.
authors.forename: Erica A K
authors.initials: EA
authors.lastname: DePasquale
authors.affiliation: 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio.
authors.forename: Amanda E
authors.initials: AE
authors.lastname: Gardner
authors.affiliation: 3 Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham , Birmingham, Alabama.
authors.forename: Candace L
authors.initials: CL
authors.lastname: Floyd
authors.affiliation: 2 Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati , Cincinnati, Ohio.
authors.forename: Robert E
authors.initials: RE
authors.lastname: McCullumsmith
mesh_terms: D000818:Animals; D000070642:Brain Injuries, Traumatic / Q000378:metabolism* / Q000523:psychology; D004195:Disease Models, Animal; D050491:Glutamate Plasma Membrane Transport Proteins / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009457:Neuroglia / Q000378:metabolism; D051381:Rats; D012377:Rodentia; D015398:Signal Transduction / Q000502:physiology; D013569:Synapses / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D050491:Glutamate Plasma Membrane Transport Proteins; D018698:Glutamic Acid
keywords: EAAT; extrasynaptic; glutamate; spillover; traumatic brain injury