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Updated: Aug 9, 2026
Controlled Cortical Impact Model for Traumatic Brain Injury
Published on: August 5, 2014
Activation of calcium/calmodulin-dependent protein kinases after traumatic brain injury
Coleen M Atkins1, Shaoyi Chen, Ofelia F Alonso
1Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
Abstract:
A prominent cognitive impairment after traumatic brain injury (TBI) is hippocampal-dependent memory loss. Although the histopathologic changes in the brain are well documented after TBI, the underlying biochemical mechanisms that contribute to memory loss have yet to be thoroughly delineated. Thus, we determined if calcium/calmodulin-dependent protein kinases (CaMKs), known to be necessary for the formation of hippocampal-dependent memories, are regulated after TBI. Sprague-Dawley rats underwent moderate parasagittal fluid-percussion brain injury on the right side of the parietal cortex. The ipsilateral hippocampus and parietal cortex were Western blotted for phosphorylated, activated alpha-calcium/calmodulin-dependent protein kinase II (alpha-CaMKII), CaMKIV, and CaMKI. alpha-Calcium/calmodulin-dependent protein kinase II was activated in membrane subcellular fractions from the hippocampus and parietal cortex 30 mins after TBI. CaMKI and CaMKIV were activated in a more delayed manner, increasing in phosphorylation 1 h after TBI. The increase in activated alpha-CaMKII in membrane fractions was accompanied by a decrease in cytosolic total alpha-CaMKII, suggesting redistribution to the membrane. Using confocal microscopy, we observed that alpha-CaMKII was activated within hippocampal neurons of the dentate gyrus, CA3, and CA1 regions. Two downstream substrates of alpha-CaMKII, the AMPA-type glutamate receptor GluR1, and cytoplasmic polyadenylation element-binding protein, concomitantly increased in phosphorylation in the hippocampus and cortex 1 h after TBI. These results demonstrate that several of the biochemical cascades that subserve memory formation are activated unselectively in neurons after TBI. As memory formation requires activation of CaMKII signaling pathways at specific neuronal synapses, unselective activation of CaMKII signaling in all synapses may disrupt the machinery for memory formation, resulting in memory loss after TBI.
Insights
Traumatic brain injury (TBI) disrupts memory by altering calcium/calmodulin-dependent protein kinases (CaMKs). These kinases, crucial for memory formation, become unselectively activated in neurons after TBI, impairing memory function.
Area of Science:
- Neuroscience
- Biochemistry
- Cellular Biology
Background:
- Traumatic brain injury (TBI) frequently causes hippocampal-dependent memory loss.
- The precise biochemical mechanisms underlying TBI-induced memory deficits remain unclear.
- Calcium/calmodulin-dependent protein kinases (CaMKs) are vital for hippocampal memory formation.
Purpose of the Study:
- To investigate the regulation of CaMKs in the hippocampus and cortex following TBI.
- To determine if CaMK activation pathways are altered after experimental TBI.
- To explore the biochemical consequences of CaMK dysregulation on memory-related substrates.
Main Methods:
- Moderate parasagittal fluid-percussion TBI was induced in Sprague-Dawley rats.
- Western blotting was used to assess phosphorylated CaMKs (alpha-CaMKII, CaMKIV, CaMKI) in subcellular fractions.
- Confocal microscopy examined alpha-CaMKII activation in hippocampal subregions.
- Phosphorylation of downstream targets (GluR1, CPEB) was analyzed.
Main Results:
- Alpha-CaMKII activation was observed in hippocampal and cortical membrane fractions 30 minutes post-TBI.
- CaMKI and CaMKIV showed delayed activation, increasing 1 hour after TBI.
- Increased membrane-bound alpha-CaMKII correlated with decreased cytosolic levels, indicating redistribution.
- Activation of alpha-CaMKII and its downstream targets (GluR1, CPEB) occurred unselectively in neurons.
Conclusions:
- TBI leads to the unselective activation of CaMK signaling cascades in neurons.
- This widespread activation, rather than synapse-specific signaling, likely disrupts memory formation machinery.
- The findings suggest a biochemical basis for memory loss following TBI, involving dysregulated CaMK pathways.
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