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Updated: May 21, 2026
Controlled Cortical Impact Model for Traumatic Brain Injury
Published on: August 5, 2014
Changes in apoptotic mechanisms following penetrating ballistic-like brain injury
Casandra M Cartagena1, Kara E Schmid, Katie L Phillips
1Department of Brain Trauma Neuroprotection and Neurorestoration, Center for Psychiatry and Neuroscience, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA. casandra.cartagena@us.army.mil
Abstract:
We investigated apoptotic pathways in a model of severe traumatic brain injury, penetrating ballistic-like brain injury (PBBI). TUNEL staining identified increasing apoptosis within 24 h. From targeted arrays, 11 genes were identified for temporal mRNA evaluation. In addition, mRNA levels and enzyme activity for caspases 3, 8, and 9 were examined. In the death receptor-mediated apoptosis pathway, the relative quantities (RQs) of mRNA for tnfr1, fas, and tnf were upregulated while trail mRNA was downregulated. In the anti-apoptotic TNF-R2 pathway, tnfr2 and flip were upregulated while xiap was downregulated. These findings indicate that increases in tnf levels following injury are not only pro-apoptotic but may also signal competing anti-apoptotic mechanisms. For the mitochondria-mediated apoptosis pathway, RQs of anti-apoptotic factors bcl2a1d and birc3 were upregulated while both bcl2 and bax were downregulated. RQs for casp 3 and casp 8 increased while casp9 decreased. Enzymatic activity increased for caspases 3, 8, and 9. While multiple mechanisms promoting and inhibiting apoptosis are at play during the first week after a PBBI, the cumulative result remains increased apoptosis. The ability to understand and dissect these events will assist in the development and evaluation of treatments targeting apoptosis following severe brain injury.
Insights
Severe traumatic brain injury triggers apoptosis via multiple pathways. Despite competing mechanisms, the net result is increased cell death, highlighting targets for future treatments.
Area of Science:
- Neuroscience
- Cell Biology
- Molecular Biology
Background:
- Severe traumatic brain injury (TBI) involves complex cellular responses, including programmed cell death (apoptosis).
- Understanding apoptotic pathways is crucial for developing effective therapeutic strategies for TBI.
Purpose of the Study:
- To investigate the temporal dynamics of apoptotic pathways following penetrating ballistic-like brain injury (PBBI) in a preclinical model.
- To identify key molecular players and signaling cascades involved in TBI-induced apoptosis.
Main Methods:
- TUNEL staining to quantify apoptosis.
- Targeted gene arrays and quantitative PCR (qPCR) to evaluate mRNA expression of apoptosis-related genes.
- Assays for caspase enzyme activity (caspases 3, 8, and 9).
Main Results:
- Apoptosis significantly increased within 24 hours post-PBBI.
- Differential regulation of death receptor (TNFR1, Fas, TNF, TRAIL) and mitochondria-mediated (Bcl-2 family, IAPs) apoptotic pathways.
- Upregulation of pro-apoptotic factors and downregulation of anti-apoptotic factors were observed, alongside complex interactions.
- Increased mRNA levels and enzymatic activity for caspases 3 and 8, while caspase 9 showed decreased mRNA but increased activity.
Conclusions:
- PBBI initiates multifaceted apoptotic signaling, involving both pro- and anti-apoptotic mechanisms.
- Despite competing pathways, the overall outcome is sustained apoptosis, indicating potential therapeutic targets.
- Dissecting these complex events is essential for developing targeted treatments for severe brain injury.
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