Book Chapter


William T. O'Connor
M. D. Gilchrist
Aoife Smyth



kcl rat stimulated levels prefrontal cortex gaba hplc glutamate basal

A Selective Depolarisation-Induced Increase in Excitatory Amino Acid Neurotransmitter Release in Rat Medial Prefrontal Cortex Using a Microdialysis Model of Traumatic Brain Injury (2005)

Abstract This study describes a microdialysis model that investigates the biochemical response of the brain to non-fatal impact trauma. A controlled cortical impact (mild and severe) was performed to the left medial prefrontal cortex (mPfc) in the isoflurane-anaesthesised rat. This was followed by intracerebral microdialysis whereby a microdialysis probe was implanted into the site of the injury. Changes in dialysate glutamate, aspartate and GABA levels were investigated immediately (i.e. 25 min) and 265 min following a local mild and severe impact to the brain. In addition, the effect of local perfusion with a depolarizing concentration of KCl (100 mM, 20 min) was also investigated 165 min after impact. Dialysate levels measured 25 min after impact (n=14) showed an impactdependent increase in glutamate (6 and 8-fold), aspartate (4 and 5-fold) and GABA (3 and 6-fold) following mild and severe impact respectively compared to non-impact controls. Dialysate levels measured 265 min after mild (n=12) and severe (n=13) impt had stabilized and continued to show a local 5-fold (mild) and 4-fold (severe) increase in local glutamate, a 6-fold (mild) and 3-fold (severe) increase in aspartate and a (3-fold (mild) and 5-fold (severe)) increase in GABA levels compared to control. Intra-mPfc KCl (n=14) increased local dialysate glutamate levels (4-fold following mild impact and 3-fold following severe impact) and aspartate levels (2-fold after both mild and severe impact) while GABA levels did not differ from non-impacted controls following either a mild or severe impact. The present findings show that microdialysis in intact brain can be combined with the controlled cortical impact model to reveal selective impact-dependent and prolonged increases in local dialysate amino acid neurotransmitter levels. Furthermore, we reveal that 165 min following either a mild or severe impact to the left mPfc KCl-stimulated glutamate and aspartate release is abnormally increased while GABA release is not different compared to non-impacted controls. Ths finding may in part explain the excitotoxicity that contributes to diffuse posttraumatic lesions associated with secondary injury.
Collections Ireland -> University College Dublin -> Mechanical & Materials Engineering Research Collection
Ireland -> University College Dublin -> College of Engineering & Architecture
Ireland -> University College Dublin -> School of Mechanical and Materials Engineering

Full list of authors on original publication

William T. O'Connor, M. D. Gilchrist, Aoife Smyth

Experts in our system

William T. O'Connor
University College Dublin
Total Publications: 21
M. D. Gilchrist
University College Dublin
Total Publications: 172