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Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury
Published on: November 19, 2012
Repeated mild traumatic brain injury causes focal response in lateral septum and hippocampus
Rebecca Acabchuk1, Denise I Briggs2, Mariana Angoa-Pérez2
1Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT 06269, USA.
Aim:
To advance our understanding of regional and temporal cellular responses to repeated mild traumatic brain injury (rmTBI), we used a mouse model of rmTBI that incorporated acceleration, deceleration and rotational forces.
Materials & Methods:
A modified weight-drop method was used to compare two inter-injury intervals, rmTBI-short (five hits delivered over 3 days) and rmTBI-long (five hits delivered over 15 days). Regional investigations of forebrain and midbrain histological alterations were performed at three post-injury time points (immediate, 2 weeks and 6 weeks).
Results:
The rmTBI-short protocol generated an immediate, localized microglial and astroglial response in the dorsolateral septum and hippocampus, with the astroglial response persisting in the dorsolateral septum. The rmTBI-long protocol showed only a transitory astroglial response in the dorsolateral septum.
Conclusion:
Our results indicate that the lateral septum and hippocampus are particularly vulnerable regions in rmTBI, possibly contributing to memory and emotional impairments associated with repeated concussions.
Insights
Repeated mild traumatic brain injury (rmTBI) causes localized cellular responses in vulnerable brain regions like the lateral septum and hippocampus. The timing of injuries influences the duration and intensity of these cellular reactions.
Area of Science:
- Neuroscience
- Traumatic Brain Injury Research
- Cellular Biology
Background:
- Mild traumatic brain injury (mTBI) can have cumulative effects, especially with repeated occurrences.
- Understanding the cellular and regional brain responses to repeated mild TBI (rmTBI) is crucial for addressing long-term neurological consequences.
- Current models often lack the complexity to fully replicate the biomechanical forces involved in human rmTBI.
Purpose of the Study:
- To investigate the regional and temporal cellular responses to rmTBI using a mouse model.
- To compare the effects of different inter-injury intervals on brain tissue.
- To identify specific brain regions vulnerable to rmTBI.
Main Methods:
- A modified weight-drop method was employed to induce rmTBI in mice.
- Two injury intervals were compared: rmTBI-short (5 hits over 3 days) and rmTBI-long (5 hits over 15 days).
- Histological analysis of forebrain and midbrain was conducted at immediate, 2-week, and 6-week post-injury time points.
Main Results:
- The rmTBI-short protocol induced immediate, localized microglial and astroglial responses in the dorsolateral septum and hippocampus.
- A persistent astroglial response was observed in the dorsolateral septum following the rmTBI-short protocol.
- The rmTBI-long protocol resulted in only a transient astroglial response in the dorsolateral septum.
Conclusions:
- The lateral septum and hippocampus are identified as highly vulnerable regions following rmTBI.
- These vulnerable regions may play a significant role in the memory and emotional deficits associated with repeated concussions.
- The study highlights the importance of injury interval in modulating cellular responses to rmTBI.
