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Brain hydroxyl radical generation in acute experimental head injury
E D Hall1, P K Andrus, P A Yonkers
1Central Nervous System Diseases Research, Upjohn Company, Kalamazoo, Michigan.
Journal of Neurochemistry
|February 1, 1993
Summary
Brain hydroxyl radical (.OH) generation increases transiently after concussive head injury in mice. This oxidative stress marker peaks within 30 minutes, indicating a rapid but temporary response to trauma.
Area of Science:
- Neuroscience
- Biochemistry
- Toxicology
Background:
- Concussive head injuries can lead to secondary brain damage.
- Oxidative stress, particularly hydroxyl radical (.OH) generation, is implicated in traumatic brain injury pathogenesis.
- Understanding the temporal dynamics of .OH production is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the time course and intensity of hydroxyl radical (.OH) generation in the brain following moderate and severe concussive head injury in mice.
- To determine if .OH generation is a transient or sustained phenomenon post-injury.
- To explore the potential contribution of metabolic hydroxylation to post-traumatic .OH production.
Main Methods:
- Male CF-1 mice were subjected to moderate or severe concussive head injury.
- Hydroxyl radical (.OH) production was assessed using the salicylate trapping method, measuring dihydroxybenzoic acid (DHBA) levels in brain tissue.
- Mice were administered salicylate and, in some cases, SKF-525A (a microsomal drug oxidation inhibitor) or saline perfusion.
- Brain tissue was collected at various time points post-injury for DHBA analysis.
Main Results:
- Moderate head injury caused a significant increase in 2,5-dihydroxybenzoic acid (DHBA) by 1 minute post-injury, peaking at 15 minutes.
- The increase in DHBA levels lost statistical significance by 30 minutes after moderate injury, indicating transient .OH generation.
- Severe head injury showed a peak increase in both 2,3- and 2,5-DHBA at 30 minutes post-injury.
- Pretreatment with SKF-525A did not attenuate the post-traumatic increase in 2,5-DHBA, suggesting it is not due to increased metabolic hydroxylation.
- Saline perfusion to remove intravascular blood eliminated the injury-induced increase in brain 2,5-DHBA.
Conclusions:
- Concussive head injury induces a rapid, transient increase in brain hydroxyl radical (.OH) generation in mice.
- The observed .OH production is unlikely to be mediated by increased microsomal drug oxidation.
- The results suggest that peripheral blood contributes to the measured hydroxyl radical increase in the brain post-injury, highlighting the importance of considering vascular integrity in TBI research.