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bioRxiv · 10.1101/2025.04.28.651041

MILD TRAUMATIC BRAIN INJURY IMPAIRS EPISODIC MEMORY IN RATS

Nah, G.·Antonopoulos, M.·Hohmann, A. G.·Port, N.·Crystal, J. D.
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Abstract

Mild traumatic brain injury (mTBI) is the most common type of traumatic brain injury. Symptoms following mTBI fall into physical, emotional, sleep, and cognitive categories, with memory deficits being a commonly documented sequelae. Whereas many animal models of mTBI exist, relatively few studies have examined the cognitive deficits of mTBI with human-like cognitive tasks. The Wayne State University Closed Head Weight Drop Model recapitulates critical physical elements of sport-related concussions and trauma-based mTBI. However, until now, this model has not previously been evaluated using a human-like memory task. Rats were trained in an odor-based item-in-context task that dissociates episodic and non-episodic memory (Panoz-Brown et al., Current Biology, 2016). The animals then underwent either a weight drop or a sham procedure. After the manipulation, animals were assessed in the item-in-context task. Episodic memory was significantly impaired in the injured rats by over 10% but not in the sham rats. Non-episodic memory was not impaired in either group. Additionally, a time-course immunohistochemical analysis of the hippocampus was performed to examine possible time-dependent changes in ionized calcium-binding adaptor molecule 1 (iba1), a marker of activated microglia/macrophages and glial fibrillary acidic protein (GFAP), a marker of astrocytes. Concussion injury was associated with time-dependent morphological changes in astrocytes and microglia in injured rats compared to sham rats. This study is the first to document episodic memory impairment in an animal model of mTBI.

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Nah, G., Antonopoulos, M., Hohmann, A. G., Port, N., Crystal, J. D.. 2025-05-02. MILD TRAUMATIC BRAIN INJURY IMPAIRS EPISODIC MEMORY IN RATS. https://doi.org/10.1101/2025.04.28.651041

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