A Mouse Model of Single and Repetitive Rotational Closed Head Concussive Brain Injury

Summary

A reproducible mouse model of rotational concussive brain injury is described, providing a versatile method to investigate the subtle functional and biological underpinnings - including neurovascular, inflammatory, and behavioral changes - following single or repetitive impact in the absence of overt structural brain damage.

Abstract

Concussive brain injury (CBI), the pathophysiological substrate underlying clinical concussion, is a frequent yet insufficiently understood condition with potential long-term neurological impairment in a subset of patients. Especially repetitive CBI, i.e., in contact sports, has been associated with lasting cognitive deficits and progressive neurodegeneration (e.g., chronic traumatic encephalopathy, CTE). To address this knowledge gap, a reproducible mouse model of closed-head rotational brain injury that recapitulates key biomechanical and pathological features of CBI was established. A stereotactically guided electromagnetic impactor was used to deliver a standardized strike to the intact skull. To reduce focal strain on the skull and adjacent brain tissue, the impactor tip was fitted with a custom-made silicone cap. This configuration reliably induced head rotation with low inter-animal variability while preventing skull fractures or microscopic tissue injury. To preserve physiological neuronal and vascular activity and to avoid potentially neuromodulatory effects of deep anesthesia, brain injury was induced in conscious mice under light sedation using the α2-agonist medetomidine. The induced impacts caused reproducible rotational head motion with only minor variability attributable to head positioning. Structural brain integrity was assessed using in vivo T2-weighted magnetic resonance imaging and confirmed by ex vivo histological analyses, which revealed no evidence of tissue disruption, contusion, or microbleeds but demonstrated a mild, widespread disruption of the microvascular interface. This novel model of rotational closed-head brain injury provides a robust experimental platform for longitudinal investigations of subtle neurovascular, inflammatory, and blood-brain barrier alterations that occur in the absence of overt structural pathology. Its application enables mechanistic insights into the pathophysiology of clinical concussion and potential neurodegenerative consequences of repetitive injury, thereby facilitating the development of urgently needed clinical biomarkers.

Introduction

Traumatic brain injury (TBI) remains a significant cause of long-term disability across all age groups, with adolescents and young adults disproportionately affected^1,2,3. The vast majority of TBIs are classified as mild (mTBI), commonly referred to as a concussion at the clinical level. Although concussion is by definition not associated with overt structural brain damage detectable by conventional neuroimaging, increasing evidence suggests that the underlying injury mechanism—here referred to as concussive brain injury (CBI)—represents a distinct and cl....

Protocol

All animal procedures complied with the German Animal Welfare Act and were approved by institutional and governmental authorities (LANUV Nordrhein-Westfalen; AZ 81-02.04.2020.A058). Experiments were conducted following ARRIVE guidelines. A schematic workflow is detailed in Figure 1. This protocol reliably induces concussive brain injury, as evidenced by a defined panel of structural, behavioral, and neurovascular validation outcomes (Figure 2). All materials used in this study are detailed in the Table of Materials.

1. General considerations

Results

General considerations:

Application of this protocol reproducibly induces concussive brain injury, as demonstrated by a defined set of structural, behavioral, and neurovascular validation readouts (see Figure 2). Structural integrity was preserved following injury. No overt macroscopic tissue disruption or hemorrhage was detected, indicating that the protocol induces concussive rather than contusive brain injury. Histological assessment confirmed.......

Discussion

A novel mouse model of closed-head CBI based on acceleration-deceleration injury is characterized, featuring a mild yet widespread impairment of the BBB and a distinct neuropsychiatric phenotype reminiscent of clinical concussion. By reproducing key hallmarks of CBI in a controlled and consistent manner while preserving structural integrity, the model provides a useful and well-characterized experimental framework for studying the mechanisms underlying CBI and its neuropsychiatric and cognitive sequelae.

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Medication
Antipamezole	Vetoquinol	VM 06043/4004	Medetomidine antagonist (α2-adrenoceptor antagonist), subcutaneous (0.5 mg/kg)
Bepanthen Ophthalmic Ointment	Bayer	11809917	Eye protection during anesthesia, topical
Bupivacaine	Sigma-Aldrich	B1160000	Local anesthesia, subcutaneous (0.1 mg/kg)
Isoflurane	CP pharma	1214CN	Anesthesia, inhalation (induction and maintenance)
Medotomidine	Vetoquinol	VM 06043/4003	Sedative/anesthetic adjunct (α2-adrenoceptor agonist), subcutaneously (0.5 mg/kg)
Tramadol hydrochloride (100 mg/mL)	Grünenthal	6867645	Analgesic administered via drinking water, 1 mg/mL final concentration for mice, from 2 days pre- to 3 days post-surgery
Equipment
Polyethylene neck cusion	Custom		Support for prone positioning during impact
Sterotaxic Impactor Silupran Cover	Custom		Distributes mechanical load, prevents focal skull damage, attached to impactor tip, 830 kPa
Streotaxic Impactor	Leica Biosystems	39463923/IM10131	Electromagnetic impact device for controlled impact delivery
Tools
GoPro Hero6	GoPro Inc., San Mateo, CA, USA
Kinovea		(version 2025.2.0)
MATLAB	MathWorks, Natick, MA, USA	NA