Researcher(s)
- Tianna Muiruri, Psychology, Delaware State University
Faculty Mentor(s)
- Liyun Wang, Mechanical Engineering, University of Delaware
Abstract
Title: Investigation of cellular responses in coup and contrecoup regions of murine brains following moderate unilateral impact loading
Author(s): Tianna Muiruri; Rosa Guerra; Tim Kamalitdinov; Liyun Wang
Introduction: Approximately 69 million people sustain a traumatic brain injury each year worldwide, with concussions accounting for nearly 70–90% of all cases. Previous experiments have demonstrated increased glial fibrillary acidic protein (GFAP) expression of glia cells being a hallmark in the brain following traumatic injuries. However, it remains unclear whether moderate concussive injuries without open skull fractures induce GFAP expression in the contrecoup hemisphere. Therefore, this study aimed to compare the GFAP expression in the contrecoup vs. coup hemisphere using a mouse unilateral head impact model and immunohistochemical staining.
Methods: Brain Specimens were collected from adult mice of 6 to 11 months of age (N = 24, 13 females and 11 males). A unilateral closed-skull concussion was induced on the anesthetized mouse by dropping a 1-kg lead weight from a 50cm height onto a level that delivered an impact loading only on the left side of the brain (coup region) while the right side (contrecoup region) was not directly impacted. Three days post injury, animals underwent transcardial perfusion with phosphate-buffered saline (PBS) followed by 4% paraformaldehyde (PFA). Brains were extracted, post-fixed in 4% PFA, embedded in optimal cutting temperature (OCT) compound, and cryosectioned to obtain a series of coronal sections spanning the brain. Immunofluorescence staining was performed to identify GFAP positive astrocytes along with DAPI nuclei staining. Some samples were used for practicing. Stained sections (five per mouse) from 8 impacted mice and 4 sham control mice without experiencing impact loading were imaged and evaluated.
Results: The nuclei staining of the five evenly spaced sections showed the both coup and contrecoup regions of the brain. No overt structural damage was observed. However, the green GFAP signal, unlike those published in literature and our previous batch, were weak and diffusive in both sham and impacted samples, making it impossible to detect GFAP distribution patterns.
Conclusion: This summer research demonstrated the feasibility of sequential sectioning of the brain tissues while more troubleshooting of the IHC protocol is needed.
Funder(s) Acknowledgements: This study was supported by the Delaware INBRE program, with a grant from the National Institute of General Medical Sciences – NIGMS (P20 GM103446) from the National Institutes of Health & the State of Delaware, as well as DCMR Research Core funded by an NIH COBRE grant (P20 GM139760).