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Updated: Jul 15, 2026
Controlled Cortical Impact Model for Traumatic Brain Injury
Published on: August 5, 2014
Apoptotic and antiapoptotic mechanisms after traumatic brain injury
R W Keane1, S Kraydieh, G Lotocki
1Department of Physiology, University of Miami School of Medicine, Florida 33136, USA.
Abstract:
Caspase and inhibitor of apoptosis (IAP) expression was examined in rats subjected to moderate traumatic brain injury (TBI) using a parasagittal fluid-percussion brain insult (1.7 to 2.2 atm). Within 1 hour after injury, caspase-8 and -9, two initiators of apoptosis, were predominantly expressed in superficial cortical areas adjacent to the impact site and in the thalamus. Caspase-3, an effector caspase, was evident at 6 hours throughout the traumatized cerebral cortex and hippocampus. Moreover, the authors observed that XIAP, cIAP-1, and cIAP-2, members of the IAP family, were constitutively expressed in the brain. Colocalization of XIAP-immunolabled cells with cell-specific markers indicated that XIAP is expressed within neurons and a subpopulation of oligodendrocytes. Immunoblots of brain extracts revealed that the processed forms of caspase-8, -9, and -3 are present as early as 1 hour after trauma. The appearance of activated caspases corresponded with the detection of cleavage of XIAP into fragments after injury and a concomitant increase in the levels of cIAP-1 and cIAP-2 in the traumatized hemispheres. The current data are consistent with the hypotheses that caspases in both the extrinsic and intrinsic apoptotic pathways are activated after moderate TBI and that IAPs may have a protective role within the brain with alterations in levels and cleavage of IAPs that contribute to cell death in this setting.
Insights
Traumatic brain injury (TBI) activates caspases, key cell death proteins, in the brain. Inhibitors of apoptosis proteins (IAPs) show altered expression and cleavage, suggesting a role in TBI-induced cell death.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Traumatic brain injury (TBI) is a significant cause of mortality and disability.
- Apoptosis plays a critical role in secondary brain damage following TBI.
- Caspases and Inhibitors of Apoptosis Proteins (IAPs) are key regulators of apoptosis.
Purpose of the Study:
- To investigate the expression and activation of caspases and IAPs in the rat brain after moderate TBI.
- To determine the cellular localization of these proteins in response to injury.
- To explore the potential role of IAPs in TBI-induced cell death.
Main Methods:
- Rats were subjected to moderate TBI using a parasagittal fluid-percussion model.
- Immunohistochemistry was used to examine caspase and IAP expression.
- Immunoblots were performed to detect processed forms of caspases and IAP cleavage.
- Colocalization studies identified cell types expressing XIAP.
Main Results:
- Initiator caspases (caspase-8, -9) and effector caspase (caspase-3) were upregulated in specific brain regions post-TBI.
- Activated caspases were detected as early as 1 hour after injury.
- XIAP, cIAP-1, and cIAP-2 were constitutively expressed but showed altered levels and cleavage post-TBI.
- XIAP was found in neurons and oligodendrocytes.
Conclusions:
- Moderate TBI activates caspases in both extrinsic and intrinsic apoptotic pathways.
- IAPs are expressed in neurons and oligodendrocytes and their alterations post-TBI may contribute to cell death.
- These findings suggest a potential protective role for IAPs in the brain following TBI, with dysregulation contributing to pathology.
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