title: Targeted over-expression of glutamate transporter 1 (GLT-1) reduces ischemic brain injury in a rat model of stroke.
abstract: Following the onset of an ischemic brain injury, the excitatory neurotransmitter glutamate is released. The excitotoxic effects of glutamate are a major contributor to the pathogenesis of a stroke. The aim of this study was to examine if overexpression of a glutamate transporter (GLT-1) reduces ischemic brain injury in a rat model of stroke. We generated an adeno-associated viral (AAV) vector expressing the rat GLT-1 cDNA (AAV-GLT1). Functional expression of AAV-GLT1 was confirmed by increased glutamate clearance rate in non-stroke rat brain as measured by in vivo amperometry. AAV-GLT1 was injected into future cortical region of infarction 3 weeks prior to 60 min middle cerebral artery occlusion (MCAo). Tissue damage was assessed at one and two days after MCAo using TUNEL and TTC staining, respectively. Behavioral testing was performed at 2, 8 and 14 days post-stroke. Animals receiving AAV-GLT1, compared to AAV-GFP, showed significant decreases in the duration and magnitude of extracellular glutamate, measured by microdialysis, during the 60 minute MCAo. A significant reduction in brain infarction and DNA fragmentation was observed in the region of AAV-GLT1 injection. Animals that received AAV-GLT1 showed significant improvement in behavioral recovery following stroke compared to the AAV-GFP group. We demonstrate that focal overexpression of the glutamate transporter, GLT-1, significantly reduces ischemia-induced glutamate overflow, decreases cell death and improves behavioral recovery. These data further support the role of glutamate in the pathogenesis of ischemic damage in brain and demonstrate that targeted gene delivery to decrease the ischemia-induced glutamate overflow reduces the cellular and behavioral deficits caused by stroke.
authors.affiliation: Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America. bharvey@mail.nih.gov
authors.forename: Brandon K
authors.initials: BK
authors.lastname: Harvey
authors.forename: Mikko
authors.initials: M
authors.lastname: Airavaara
authors.forename: Jason
authors.initials: J
authors.lastname: Hinzman
authors.forename: Emily M
authors.initials: EM
authors.lastname: Wires
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Chiocco
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Howard
authors.forename: Hui
authors.initials: H
authors.lastname: Shen
authors.forename: Greg
authors.initials: G
authors.lastname: Gerhardt
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Hoffer
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
mesh_terms: D027322:Amino Acid Transport System X-AG / Q000378:metabolism*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D020520:Brain Infarction / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D001930:Brain Injuries / Q000150:complications* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D002545:Brain Ischemia / Q000150:complications* / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D002540:Cerebral Cortex / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D000229:Dependovirus; D004195:Disease Models, Animal; D005786:Gene Expression Regulation; D005971:Glutamates / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020287:In Situ Nick-End Labeling; D020244:Infarction, Middle Cerebral Artery / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D020127:Recovery of Function / Q000502:physiology; D020521:Stroke / Q000150:complications* / Q000473:pathology / Q000503:physiopathology
chemical_list: D027322:Amino Acid Transport System X-AG; D005971:Glutamates