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Microdialysis of Excitatory Amino Acids During EEG Recordings in Freely Moving Rats
Published on: November 8, 2018
Investigation of extracellular amino acid release in children with severe head injury using microdialysis. A pilot
C Tolias1, D Richards, N Bowery
1Department of Neurosurgery and Institute of Child Health, Birmingham Children's Hospital, UK.
Insights
Severe pediatric head injury shows unique amino acid patterns. Excitatory amino acid release in children appears active, unlike adult models, suggesting distinct pathophysiology in pediatric traumatic brain injury.
Area of Science:
- Neuroscience
- Pediatric Neurology
- Traumatic Brain Injury Research
Background:
- Microdialysis is established for adult severe head injury research.
- Limited data exists on pediatric severe head injury pathophysiology.
- Understanding pediatric TBI is crucial for effective treatment.
Purpose of the Study:
- To investigate amino acid changes in children with severe head injury using microdialysis.
- To compare pediatric findings with existing adult and animal models.
- To explore the role of excitatory amino acids and nitric oxide metabolism in pediatric TBI.
Main Methods:
- Microdialysis probe insertion in five children with severe head injury (GCS < 8).
- Hourly sampling for amino acid analysis via High Performance Liquid Chromatography.
- Monitoring of glutamate, aspartate, glutamine, and citrulline levels.
Main Results:
- Glutamate and aspartate levels were inversely related to glutamine, suggesting active release, not just cell death.
- Extracellular glutamate levels may be influenced by uptake and metabolism in children.
- Nitric oxide metabolite citrulline levels were stable, indicating a different pattern than glutamate release.
Conclusions:
- Amino acid release in pediatric severe head injury differs from adult patterns and cell/animal studies.
- Excitatory amino acid release in children is likely an active process.
- Pediatric TBI pathophysiology may involve distinct mechanisms compared to adults.
Abstract:
Microdialysis has been used to investigate the pathophysiology of severe head injury in adults. No similar data exist, however, for children. As part of routine neuromonitoring, five children with severe, closed head injury (GCS < 8) were fitted with a microdialysis probe (CMA 70) at the time of intracranial pressure bolt insertion. Samples were collected at hourly intervals prior to analysis of amino acids by High Performance Liquid Chromatography. In contrast to adult patients, glutamate and aspartate did not correlate with structural amino acid levels and were inversely related to glutamine levels, suggesting that excitatory aminoacid release in children with severe head injury is likely to be an active process rather than an effect of indiscriminate cell destruction and that glutamate levels extracellularly may also depend on glutamate uptake and metabolism. The nitric oxide metabolite citrulline remained at similar levels in different patients throughout the monitoring period, indicating that nitric oxide metabolism may not follow the pattern of glutamate release. Our study is suggesting that amino acid release in severe head injury in children may not correspond to the recognised patterns from cell culture and animal studies and may also differ from that in adults.
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