We want to thank all the fellows in the Department of Laboratory Animals of Central South University. This study was supported by the National Natural Science Foundation of China (No. 81971791); Shanghai Key Lab of Forensic Medicine, Key Lab of Forensic Science, Ministry of Justice, China (Academy of Forensic Science) (No. KF202104).

Animal experiments were approved by the Central South University Animal Care and Use Committee. All studies were conducted in line with the welfare and ethical principles of laboratory animals.
1. Animal feeding and anesthetization procedure
<ol>
	<li>Group house 280-320 g Sprague-Dawley male rats and maintain them on a 12 h/12 h light/dark cycle with access to food and water ad libitum. Perform the study after the rats acclimatize for 6 days.</li>
	<li>Anesthetize the rat with 3% isoflurane at 0.6 L/min air flow in an induction box until it is non-responsive to paw or tail pinch. Maintain the flow rate for 30 s. 
	NOTE: Pain medications were not used as they would interfere with the rat&#39;s response in the neurobehavioral assessments.</li>
</ol>
2. Preoperative setup
<ol>
	<li>Position a sponge with a hardness value of 35D (weight of 35 kg/m3 of sponge), with identical length and width but a thickness of 12 cm, within an acrylic box (15 cm x 22 cm x 43 cm) lacking a top cover.</li>
	<li>Trim a tin foil (a thickness of 20 &#181;m) and affix it onto the acrylic box using adhesive tape to form a destructible surface capable of supporting the weight of a rat. Additionally, mark a cut line measuring approximately 10 cm to be the designated location for positioning the rat&#39;s head.</li>
	<li>With the aid of an iron stand, firmly secure the PVC tube in place. Prepare a perforated weight, weighing 550 grams with an 18-millimeter diameter. Attach the weight to a fishing line at a height of 1 meter inside a polyvinyl chloride or PVC tube. and adjust the position of the guide tube 3 centimeters above the tin foil.</li>
	<li>Prepare a helmet and a pillow. Make a helmet using a stainless-steel disk measuring 10 mm in diameter and 3 mm in thickness. Prepare a wedge-shaped sponge pillow to place beneath the rat&#39;s head, ensuring that it is perpendicular to the direction of gravity. 
	NOTE: A schematic diagram of the impact apparatus is presented in Figure 1. The helmet serves the purpose of identifying the impact location and enhancing the distribution of external force. The pillow is utilized to guarantee uniform and stable damage.</li>
</ol>
3. mTBI induction
<ol>
	<li>Quickly place the anesthetized rat on its chest on the tin foil. 
	NOTE: Two operators are required for mTBI induction-one for the preparation and the other for verification.</li>
	<li>Preparation: Place the pillow beneath the rat, ensuring its head is parallel to the foil paper. Align the helmet with the rat&#39;s ears and secure it in place.</li>
	<li>Verification: Verify that the PVC pipe is positioned directly above the helmet. Once both operators confirm the correct setup, proceed to the next step.</li>
	<li>Induction of head rotation: Release the weight, allowing it to fall and strike the rat&#39;s head, inducing a fall onto the sponge and a 180&#176; rotation.</li>
	<li>Place the rat on its back in a clean cage.</li>
</ol>
4. Sham induction
<ol>
	<li>Treat the rat the same way as the previous mTBI induction description, but do not subject it to the head impact.</li>
</ol>
5. Validation procedure: Acute neurobehavioral assessments
NOTE: The following assessments were modified based on the Neurological Severity Scores9 and the protocol by Flierl et al.10. All these assessments were performed 10 min after the rat recovered the righting reflex.
<ol>
	<li>Time of loss of consciousness: Record the duration from when the rat is anesthetized to when it recovers the righting reflex. 
	NOTE: The righting reflex is the process in which the rat turns over when placed on its back. Loss of righting reflex is to be considered as a humane endpoint, and the animal must be euthanized as per institutional guidelines.</li>
	<li>First seeking-behavior time: Record the duration from when the rat is anesthetized to when it shows the seeking behavior for the first time. 
	NOTE: Seeking behavior is a sign of interest in the environment, a physiological response.</li>
	<li>Ability to escape
	<ol>
		<li>Place the rat in the middle of a circular apparatus (0.5 m diameter and 0.3 m height) with an exit (12.5 cm long and 9 cm wide).</li>
		<li>Record the time the rat takes to exit the circle. 
		NOTE: If the rat does not exit the circle within 180 s, record the time as 180 s.</li>
	</ol>
	</li>
	<li>Beam balance ability test
	<ol>
		<li>Place the rat on a 3 cm, 2 cm, and 1.5 cm wide beam for 1 min accordingly.</li>
		<li>If the rat maintains a balance with a steady posture on the beam, score it as 0.</li>
		<li>If the rat grasps the side of the beam, give a score of 1. If the rat hugs the beam and one limb falls off it, score it as 2.</li>
		<li>If the rat hugs the beam and the two limbs fall off it or spin on it (&#62;60 s), score it as 3.</li>
		<li>If the rat attempts to balance on the beam but falls off (&#62; 40 s), score it as 4.</li>
		<li>If the rat attempts to balance on the beam but falls off (&#62;20 s), score it as 5.</li>
		<li>If the rat does not attempt to balance or hang on the beam and falls off within 20 s, score it as 6. 
		NOTE: The beam balance test does not require a pre-trial.</li>
	</ol>
	</li>
</ol>
6. Validation procedure: Neurobehavior assessment
NOTE: Prior to the behavioral experiments, the rats were handled for 2 min daily for 3 consecutive days to minimize stress and novelty disruption. All behavioral experiments were performed by placing the animals in the test environment for 60 min prior to the start of the experiment.
<ol>
	<li>Motor coordination ability (Beam task)
	<ol>
		<li>Experimental setup
		<ol>
			<li>Place the rats on one end of the balance beam (1.5 m long and 75 cm above the floor). Place an escape box (a slanted bedding home cage) on the other end.</li>
			<li>Position a foam padding below the beam to mitigate the potential risk of injury to rats in case of falls during the test.</li>
			<li>Turn on the video camera.</li>
			<li>Schedule testing days at specific time points post-injury or post-sham treatment (e.g., day 1, day 3, and day 7).</li>
		</ol>
		</li>
		<li>Training phase (2 days)
		<ol>
			<li>Train the rats to cross the 4 cm wide beam 3 consecutive times, followed by two trials on the 2 cm wide beam.</li>
			<li>During the training, gently guide the rats across the beam until they can cross them easily without interference.</li>
		</ol>
		</li>
		<li>Balance beam experiment
		<ol>
			<li>Place the rats on the 2 cm wide beam for 5 consecutive trials.</li>
			<li>Record the start and end of each trial when the rat&#39;s nose crosses the starting and finishing lines, respectively.</li>
			<li>Return the rats to their cages at the end of the experiment.</li>
		</ol>
		</li>
		<li>Baseline testing
		<ol>
			<li>Conduct the balance beam experiment before the injury or treatment.</li>
			<li>Calculate the average values from these 5 consecutive trials to establish the baseline for each rat.</li>
		</ol>
		</li>
		<li>Data analysis
		<ol>
			<li>Analyze the time to cross the beam and the total number of hindfoot slips using video analysis by researchers blinded to the experimental conditions.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Anxiety (Open field test)
	<ol>
		<li>Experimental setup
		<ol>
			<li>Prepare the open field arena, ensuring it is clean and free from any previous odor cues. Divide the arena into three zones: a central inner zone (33 cm x 33 cm), a middle zone (66 cm x 66 cm), and an outer zone.</li>
		</ol>
		</li>
		<li>Testing phase
		<ol>
			<li>Place a rat in the center of the open field arena and start the timer. Allow the rat to explore the arena for 5 min freely. After 5 min, carefully and gently return the rat to its home cage.</li>
		</ol>
		</li>
		<li>Data collection
		<ol>
			<li>Measure the total distance traveled by the rat during the 5-minute exploration period. Determine the time the rat spends in the central inner, middle, and outer zones.</li>
		</ol>
		</li>
		<li>Data analysis
		<ol>
			<li>Use the total distance traveled as a measure of overall exploratory behavior and locomotor ability. Calculate the time spent in the central inner zone as an indicator of anxiety-like responses.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Learning and memory abilities (Morris water maze test)
	<ol>
		<li>Ensure the water maze apparatus is in proper condition. Dye the water black and place cues in the four cardinal directions. Position the platform 2.5 cm below the water surface.</li>
		<li>Set up a monitoring system to record and observe the behavior of the rats.</li>
		<li>Trail day
		<ol>
			<li>Quickly place the rat into the water maze. If the rat fails to reach the platform within 2 min, gently guide it using the wooden stick.</li>
			<li>Allow the rat to familiarize itself with the maze environment while standing on the platform for 20 s, then remove it. Once the rat is on the platform, let it stay for 20 s, then remove it.</li>
		</ol>
		</li>
		<li>Daily repetition
		<ol>
			<li>Repeat the training day procedure, placing the rat in the water from different quadrants. Repeat step 6.3.3. Continue the training for 5 consecutive days.</li>
		</ol>
		</li>
		<li>Probe test day: On the 6th day, remove the platform and place the rat in the same quadrant for 2 min.</li>
		<li>Observation and recording: Utilize the monitoring system to monitor the rat&#39;s behavior on trial and probe test days.</li>
		<li>Cleaning: After removing the rat from the water maze, use a towel to dry it thoroughly.</li>
	</ol>
	</li>
</ol>

Validating Injury Response and Behavioral Assessments in an mTBI Rat Model

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	<li>Silverberg, N. D., Duhaime, A. C., Iaccarino, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mild+traumatic+brain+injury+in+2019-2020.">Mild traumatic brain injury in 2019-2020.</a> JAMA. 323 (2), 177-178 (2020).</li><li>Kim, K., Priefer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+current+post-concussion+protocols.">Evaluation of current post-concussion protocols.</a> Biomedicine &amp; Pharmacotherapy. 129, 110406 (2020).</li><li>Peeters, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+traumatic+brain+injury+in+Europe.">Epidemiology of traumatic brain injury in Europe.</a> Acta Neurochirurgica (Wien). 157 (10), 1683-1696 (2015).</li><li>Kabadi, S. V., Hilton, G. D., Stoica, B. A., Zapple, D. N., Faden, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluid-percussion-induced+traumatic+brain+injury+model+in+rats.">Fluid-percussion-induced traumatic brain injury model in rats.</a> Nature Protocols. 5 (9), 1552-1563 (2010).</li><li>Smith, D. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+of+parasagittal+controlled+cortical+impact+in+the+mouse:+cognitive+and+histopathologic+effects.">A model of parasagittal controlled cortical impact in the mouse: cognitive and histopathologic effects.</a> Journal of Neurotrauma. 12 (2), 169-178 (1995).</li><li>Feeney, D. M., Boyeson, M. G., Linn, R. T., Murray, H. M., Dail, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responses+to+cortical+injury:+I.+Methodology+and+local+effects+of+contusions+in+the+rat.">Responses to cortical injury: I. Methodology and local effects of contusions in the rat.</a> Brain Research. 211 (1), 67-77 (1981).</li><li>Cernak, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pathobiology+of+blast+injuries+and+blast-induced+neurotrauma+as+identified+using+a+new+experimental+model+of+injury+in+mice.">The pathobiology of blast injuries and blast-induced neurotrauma as identified using a new experimental model of injury in mice.</a> Neurobiology of Disease. 41 (2), 538-551 (2011).</li><li>Shultz, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+potential+for+animal+models+to+provide+insight+into+mild+traumatic+brain+injury:+Translational+challenges+and+strategies.">The potential for animal models to provide insight into mild traumatic brain injury: Translational challenges and strategies.</a> Neuroscience and Biobehavioral Reviews. 76 (Pt B), 396-414 (2017).</li><li>Chen, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+benefit+of+intravenous+administration+of+bone+marrow+stromal+cells+after+cerebral+ischemia+in+rats.">Therapeutic benefit of intravenous administration of bone marrow stromal cells after cerebral ischemia in rats.</a> Stroke. 32 (4), 1005-1011 (2001).</li><li>Flierl, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+closed+head+injury+model+induced+by+a+weight-drop+device.">Mouse closed head injury model induced by a weight-drop device.</a> Nature Protocols. 4 (9), 1328-1337 (2009).</li><li>Kane, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mouse+model+of+human+repetitive+mild+traumatic+brain+injury.">A mouse model of human repetitive mild traumatic brain injury.</a> J Neuroscience Methods. 203 (1), 41-49 (2012).</li><li>Mychasiuk, R., Farran, A., Esser, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+an+experimental+rodent+model+of+pediatric+mild+traumatic+brain+injury.">Assessment of an experimental rodent model of pediatric mild traumatic brain injury.</a> Journal of Neurotrauma. 31 (8), 749-757 (2014).</li><li>Pham, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mild+closed-head+injury+in+conscious+rats+causes+transient+neurobehavioral+and+glial+disturbances:+A+novel+experimental+model+of+concussion.">Mild closed-head injury in conscious rats causes transient neurobehavioral and glial disturbances: A novel experimental model of concussion.</a> Journal of Neurotrauma. 36 (14), 2260-2271 (2019).</li><li>Jacotte-Simancas, A., Molina, P., Gilpin, N. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repeated+mild+traumatic+brain+injury+and+JZL184+produce+sex-specific+increases+in+anxiety-like+behavior+and+alcohol+consumption+in+Wistar+rats.">Repeated mild traumatic brain injury and JZL184 produce sex-specific increases in anxiety-like behavior and alcohol consumption in Wistar rats.</a> Journal of Neurotrauma. , (2023).</li><li>Levin, H. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Association+of+sex+and+age+with+mild+traumatic+brain+injury-related+symptoms:+A+TRACK-TBI+study.">Association of sex and age with mild traumatic brain injury-related symptoms: A TRACK-TBI study.</a> JAMA Network Open. 4 (4), e213046 (2021).</li></ol>

The authors have no financial interest to disclose.

This model successfully simulates a closed-head mTBI without the need for scalp incision or skull opening, providing a more accurate representation of the impact scenario observed in human cases. The avoidance of scalp incision helps prevent inflammatory responses that may not align with the actual situation. Compared to Richelle Mychasiuk's pediatric model12, the model used in this study is specifically tailored for adult rats weighing between 280-320 g, enabling us to obtain valuable insights in...

Mild traumatic brain injury (mTBI), or concussion, is the most prevalent type of injury and can lead to various short-term and chronic symptoms1. These symptoms may include dizziness, headaches, depression, and anhedonia, among others, leading to significant suffering for individuals affected by mTBI2. Since most mTBIs are caused by blunt force trauma3, it becomes imperative to develop animal models that accurately mimic such injuries. These models are essential for gaining a better understanding of the injury and its underlying mechanisms, offering a controlled environment with reduced variability and heterogeneity compared to human studies.
Numerous well-established rodent models have been developed for traumatic brain injury (TBI), including fluid percussion injury (FPI)4, controlled cortical impact (CCI)5, weight-drop injury6, blast traumatic brain injury7, and others. However, these models primarily focus on replicating moderate to severe TBI scenarios. In contrast, the experimental models specifically designed to simulate mTBI have received relatively less attention and remain underexplored8. Therefore, there is a critical need to establish a stable and reproducible animal model that accurately represents mTBI. Such a model would significantly enhance our understanding of the neurobiological and behavioral consequences associated with mTBI.
One cannot distinguish the functional deficits in mTBI rats compared to normal rats via casual observation after the effects of anesthesia have worn off. Therefore, it is necessary to administer specific tests. In humans, a wide range of clinical assessments are used to evaluate patients9,10,11. Similarly, establishing a successful model in the rat model also requires using rapid assessment tools to determine its validity.
In this study, we present a closed-head mTBI rat model, enabling the investigation of mTBI in a manner that closely resembles the human condition. The detailed description of the model and its validation procedure provides a comprehensive understanding of the experimental approach utilized in studying mTBI.

<table><tbody><tr><td>Acrylic box</td><td>In-house</td><td>N/A</td><td>15 cm x 22 cm x 43 cm</td></tr><tr><td>Anesthesia Machine</td><td>RWD Life Science Co.</td><td>R540 Mice &amp;amp; Rat Animal Anesthesia Machine</td><td></td></tr><tr><td>Helmet</td><td>In-house</td><td>N/A</td><td>Stainless-steel disk measuring 10 mm in diameter and 3 mm in thickness</td></tr><tr><td>Morris water maze</td><td>RWD Life Science Co.</td><td></td><td>Diameter 150 cm, height 50 cm,platform diameter 35 cm</td></tr><tr><td>Open field</td><td>RWD Life Science Co.</td><td>63007</td><td>Width100 cm, height 40 cm</td></tr><tr><td>Panlab SMART V3.0</td><td>RWD Life Science Co.</td><td>SMART v3.0</td><td></td></tr><tr><td>Perforated weight</td><td>In-house</td><td>N/A</td><td>Weight of 550 g and diameter of 18 mm</td></tr><tr><td>Pillow</td><td>In-house</td><td>N/A</td><td>Wedge-shaped sponge to place beneath the rat&#039;s head</td></tr></tbody></table>

rat model of closed-head mild traumatic injury and its validation

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful insights, developing a stable and reproducible animal model is essential. In this study, we report a detailed description of a closed-head mTBI model and a representative validation method using Sprague-Dawley rats to verify the modeling effect. The model involves dropping a 550 g mass weight from a height of 100 cm directly onto the head of a rat on a destructible surface, followed by a 180-degree turn. To assess the injury, rats underwent a series of neurobehavioral assessments 10 min post-injury, including time of loss of consciousness, first seeking-behavior time, escape ability, and beam balance ability test. During the acute and subacute stages following the injury, behavioral tests were conducted to assess motor coordination ability (Beam task), anxiety (Open Field test), and learning and memory abilities (Morris Water Maze test). The closed-head mTBI model produced a consistent injury response with minimal mortality and replicated real-life situations. The validation method effectively verified the model development and ensured the stability and consistency of the model.

The apparatus used in this work was a modified version of the Kane model and Richelle Mychasiuk&#39;s pediatric model11,12. In this study, SD rats were assigned to sham and mTBI groups. To demonstrate the reproducibility of this model, we conducted three independent replicates of this model along with the acute neurobehavioral assessment, with each experiment involving 8-12 rats. In this study, we used more than 30 mTBI rats, with...

Watch this Scientific Journal Video about Advancing Traumatic Brain Injury Research — A Closed-Head Model for Accurate Replication and Rapid Assessment at JoVE.com

Author Spotlight: Advancing Traumatic Brain Injury Research - A Closed-Head Model for Accurate Replication and Rapid Assessment 

Here, we present a closed-head mild traumatic brain injury (mTBI) rat model and its validation exhibiting remarkable similarity to human mTBI concerning behavioral manifestations during the acute and subacute stages.

Rat Model of Closed-Head Mild Traumatic Injury and its Validation

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful ...

rat-model-of-closed-head-mild-traumatic-injury-and-its-validation

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Neuroscience

1.2K Views.  School of Basic Medical Science, Central South University. In deze studie introduceerden we een ratmodel met gesloten hoofd en licht traumatisch hersenletsel en gaven we een uitgebreid overzicht van de validatie ervan. Ons doel was om een eenvoudige aanpak te bieden voor het repliceren van dit type hersenletsel en een snelle beoordelingsmethode om het succes van het model te bevestigen. Dit model simuleert met succes een licht traumatisch hersenletsel met gesloten hoofd zonder dat een incisie in de hoofdhuid of schedelopening nodig is, en geeft een n...

Video: Auteur in de schijnwerpers: Onderzoek naar traumatisch hersenletsel bevorderen - een gesloten model voor nauwkeurige replicatie en snelle beoordeling 

Controlled Cortical Impact Model for Traumatic Brain Injury

Every year over a million Americans suffer a traumatic brain injury (TBI). Combined with the incidence of TBIs worldwide, the physical, emotional, social, and economical effects are staggering. Therefore, further research into the effects of TBI and effective treatments is necessary. The controlled cortical impact (CCI) model induces traumatic brain injuries ranging from mild to severe. This method uses a rigid impactor to deliver mechanical energy to an intact dura exposed following a craniectomy. Impact is made under precise parameters at a set velocity to achieve a pre-determined deformation depth. Although other TBI models, such as weight drop and fluid percussion, exist, CCI is more accurate, easier to control, and most importantly, produces traumatic brain injuries similar to those seen in humans. However, no TBI model is currently able to reproduce pathological changes identical to those seen in human patients. The CCI model allows investigation into the short-term and long-term effects of TBI, such as neuronal death, memory deficits, and cerebral edema, as well as potential therapeutic treatments for TBI.

Traumatic brain injuries (TBIs) remain a serious health problem. Using the controlled cortical impact surgery model, research on the effects of TBI and possible treatment methods may be performed.

Every year over a million Americans suffer a traumatic brain injury (TBI).  Combined with the incidence of TBIs worldwide, the physical, emotional, ...

Medicine

A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor vehicle accidents, and falls, a reliable animal model of mTBI had previously not been developed for this important aspect of development. The modified weight-drop technique employs a glancing impact to the head of a freely moving rodent transmitting acceleration, deceleration, and rotational forces upon the brain. When applied to juvenile rats, this modified weight-drop technique induced clinically relevant behavioural outcomes that were representative of post-concussion symptomology. The technique is a rapidly applied procedure with an extremely low mortality rate, rendering it ideal for high-throughput studies of therapeutics. In addition, because the procedure involves a mild injury to a closed head, it can easily be used for studies of repetitive brain injury. Owing to the simplistic nature of this technique, and the clinically relevant biomechanics of the injury pathophysiology, the modified weight-drop technique provides researchers with a reliable model of mTBI that can be used in a wide variety of behavioural, molecular, and genetic studies.

The modified weight-drop technique is an easy, cost-effective procedure used for the induction of mild traumatic brain injury in juvenile rats. This novel technique produces clinically relevant symptomology that will advance the study of mild traumatic brain injury (mTBI) and concussion.

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor ...

A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal neurological deficits and even amnesia. Athletes participating in contact sports are at high risk of exposure to large number of mTBIs. In terms of the level of injury in a sporting athlete, a mTBI is defined as a mild injury that does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Despite previous attempts to model mTBI in mice and rats, many have reported gross adverse effects including skull fractures, intracerebral bleeding, axonal injury and neuronal cell death. Herein, we describe our highly reproducible animal model of mTBI that reproduces clinically relevant symptoms. This model uses a custom made pneumatic impactor device to deliver a closed-head trauma. This impact is made under precise velocity and deformation parameters, creating a reliable and reproducible model to examine the mechanisms that contribute to effects of single or repetitive concussive mTBI.

Athletes absorb several hundred mild traumatic brain injuries (mTBI)/concussions every year; however, the consequence of these on the brain is poorly understood. Therefore, an animal model of single and repetitive mTBI that consistently replicates clinically relevant symptoms provides the means to advance the study of mTBI and concussion.

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal ...

Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.
Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of ...

Electromagnetic Controlled Closed-Head Model of Mild Traumatic Brain Injury in Mice

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and understanding the mechanisms of how a TBI alters brain function. The availability of multiple animal models of TBI is necessary to model the different aspects and severities of TBI seen in people. This manuscript describes the use of a midline closed head injury (CHI) to develop a mouse model of mild TBI. The model is considered mild because it does not produce structural brain lesions based on neuroimaging or gross neuronal loss. However, a single impact creates enough pathology that cognitive impairment is measurable at least 1 month after injury. A step-by-step protocol to induce a CHI in mice using a stereotaxically guided electromagnetic impactor is defined in the paper. The benefits of the mild midline CHI model include the reproducibility of the injury-induced changes with low mortality. The model has been temporally characterized up to 1 year after the injury for neuroimaging, neurochemical, neuropathological, and behavioral changes. The model is complementary to open skull models of controlled cortical impact using the same impactor device. Thus, labs can model both mild diffuse TBI and focal moderate-to-severe TBI with the same impactor.

The protocol describes mild traumatic brain injury in a mouse model. In particular, a step-by-step protocol to induce a mild midline closed head injury and the characterization of the animal model is fully explained.

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and ...

Assessing Changes in Synaptic Plasticity Using an Awake Closed-Head Injury Model of Mild Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of closed-head mTBI in the preclinical setting to increase translatability to the clinical population. The awake closed-headed injury (ACHI) model uses a modified controlled cortical impactor to deliver closed-headed injury, inducing clinically relevant behavioral deficits without the need for a craniotomy or the use of an anesthetic.
This technique does not normally induce fatalities, skull fractures, or brain bleeds, and is more consistent with being a mild injury. Indeed, the mild nature of the ACHI procedure makes it ideal for studies investigating repetitive mTBI (r-mTBI). Growing evidence indicates that r-mTBI can result in a cumulative injury that produces behavioral symptoms, neuropathological changes, and neurodegeneration. r-mTBI is common in youths playing sports, and these injuries occur during a period of robust synaptic reorganization and myelination, making the younger population particularly vulnerable to the long-term influences of r-mTBI.
Further, r-mTBI occurs in cases of intimate partner violence, a condition for which there are few objective screening measures. In these experiments, synaptic function was assessed in the hippocampus in juvenile rats that had experienced r-mTBI using the ACHI model. Following the injuries, a tissue slicer was utilized to make hippocampal slices to evaluate bidirectional synaptic plasticity in the hippocampus at either 1 or 7 days following the r-mTBI. Overall, the ACHI model provides researchers with an ecologically valid model to study changes in synaptic plasticity following mTBI and r-mTBI.

Here, it is demonstrated how an awake closed-head injury model can be used for examining the effects of repeated mild traumatic brain injury (r-mTBI) on synaptic plasticity in the hippocampus. The model replicates important features of r-mTBI in patients and is used in conjunction with in vitro electrophysiology.

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of ...

rmTBI Induction in Mice via a Closed-Head Injury Method

Modified Mouse Model of Repetitive Mild Traumatic Brain Injury Incorporating Thinned-Skull Window and Fluid Percussion

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models with well-defined pathologies are urgently needed for studying the mechanisms of neuropathology after mild TBI and testing therapeutics. Replicating the entire sequelae of TBI in animal models has proven to be a challenge. Therefore, the availability of multiple animal models of TBI is necessary to account for the diverse aspects and severities seen in TBI patients. CHI is one of the most common methods for fabricating rodent models of rmTBI. However, this method is susceptible to many factors, including the impact method used, the thickness and shape of the skull bone, animal apnea, and the type of head support and immobilization utilized. The aim of this protocol is to demonstrate a combination of the thinned-skull window and fluid percussion injury (FPI) methods to produce a precise mouse model of CHI-associated rmTBI. The primary objective of this protocol is to minimize factors that could impact the accuracy and consistency of CHI and FPI modeling, including skull bone thickness, shape, and head support. By utilizing a thinned-skull window method, potential inflammation due to craniotomy and FPI is minimized, resulting in an improved mouse model that replicates the clinical features observed in patients with mild TBI. Results from behavior and histological analysis using hematoxylin and eosin (HE) staining suggest that rmTBI can lead to a cumulative injury that produces changes in both behavior and gross morphology of the brain. Overall, the modified CHI-associated rmTBI presents a useful tool for researchers to explore the underlying mechanisms that contribute to focal and diffuse pathophysiological changes in rmTBI.

Author Spotlight: Optimizing Rodent Models for Investigating the Mechanisms and Rehabilitation in Repeated Mild Traumatic Brain Injury

This protocol presents a modified mouse model of repetitive mild traumatic brain injury (rmTBI) induced via a closed-head injury (CHI) method. The approach features a thinned-skull window and fluid percussion to reduce the inflammation commonly caused by meninges exposure, along with improved reproducibility and accuracy in modeling rmTBI in rodents.

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models ...

CHILD Model &#8212; Recapitulating Juvenile Concussion and Long-Term Outcomes in Mice

A Pediatric Concussion Model in Mice: Closed Head Injury with Long-Term Disorders (CHILD)

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life exhibiting debilitating physiological, neurological, and psychosocial outcomes. The cellular and molecular pathophysiological mechanisms are relatively unknown, and this significant gap effectively precludes investigations into specific therapeutic strategies to mitigate chronic sequelae. No single animal concussion model recapitulates all the features reported in human subjects, and current models are designed to answer specific research questions. We set out to develop a juvenile concussion that recapitulates clinical early, and long-term symptomology encountered, termed Closed Head Injury with Long-term Disorder (CHILD). In this model, a concussive force via an electromagnetic impactor is delivered to the head of a lightly anesthetized unrestrained post-natal day 17 (P17) mouse, allowing free rotation of the head. Mice are placed on a tightly stretched tin foil across a stereotactic device, and the impactor is carefully aligned with the targeted cortical region. The electromagnetic impactor facilitates the selection of impact depth, dwell, and duration to determine injury severity. A strength of this model is that it allows head rotation, an important clinical feature. After impact, mice are immediately monitored for righting time and time to explore their environment, followed by their return to their dam. Increasing the severity of concussion results in intracranial bleeds in a subset of mice. Mice can be routinely monitored for behavior and neuroimaging over their lifespan, as desired. Various injury severities mimic the heterogeneous nature of juvenile concussions. The current standard CHILD model exhibits no skull fracture, no observable conventional neuroimaging change (similar to clinical), but leads to progressive and persistent neuronal death, altered diffusion MRI, modified neuronal activity and plasticity, increased gliosis, and progressive behavioral perturbations with age. In summary, this CHILD model mimics the early and long-term features observed in many clinical concussion patients.

Pediatric concussions can result in long-term sequelae with physiological and psychological perturbations. This pediatric concussion mouse model results in long-term neuroinflammation, white matter alterations, and neuronal modifications with behavioral dysfunction. The model can be adapted to differential impact locations or repeated concussions to assess lifetime changes.

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life ...

Development of an Uncomplicated Mild Traumatic Brain Injury Model Modified by Weight-Drop Method and Evidenced by Magnetic Resonance Imaging

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing negative findings in routine clinical imaging in the acute phase hinders early and appropriate care in these patients. It has been acknowledged that different impact parameters may affect and even accelerate the progress of subsequent neuropsychological symptoms following mTBI. However, the association of impact parameters during concussion to the outcome has not been extensively examined. In the current study, an animal model with closed-head injury (CHI) modified from the weight-drop injury paradigm was described and demonstrated in detail. Adult male Sprague-Dawley rats (n = 20) were randomly assigned to CHI groups with different impact parameters (n = 4 per group). Longitudinal MR imaging studies, including T2-weighted imaging and diffusion tensor imaging, and sequential behavioral assessments, such as modified neurological severity score (mNSS) and the beam walk test, were conducted over a 50-day study period. Immunohistochemical staining for astrogliosis was performed on day 50 post-injury. Worse behavioral performance was observed in animals following repetitive CHI compared to the single injury and sham group. By using longitudinal magnetic resonance imaging (MRI), no significant brain contusion was observed at 24 h post-injury. Nevertheless, cortical atrophy and alteration of cortical fractional anisotropy (FA) were demonstrated on day 50 post-injury, suggesting the successful replication of clinical uncomplicated mTBI. Most importantly, changes in neurobehavioral outcomes and image features observed after mTBI were dependent on impact number, inter-injury intervals, and the selected impact site in the animals. This in vivo mTBI model combined with preclinical MRI provides a means to explore brain injury on a whole-brain scale. It also allows the investigation of imaging biomarkers sensitive to mTBI across varying impact parameters and severity levels.

Here, we present a protocol to establish a closed-head injury animal model replicating the neuroimage outcome of uncomplicated mild traumatic brain injury with the preserved brain structure in the acute phase and long-term brain atrophy. Longitudinal magnetic resonance imaging is the primary method used for evidence.

Mild traumatic brain injury (mTBI), known as concussion, accounts for more than 85% of brain injuries globally. Specifically, uncomplicated mTBI showing ...

Rat Model of Closed-Head Mild Traumatic Injury and its Validation

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