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

<ol>
	<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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<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 &#38; 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&#39;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.

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

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

In this study, we introduced a closed-head, mild traumatic brain injury rat model, and provided a comprehensive overview of its validation. Our goal was to offer a straightforward approach for replicating this type of brain injury and a rapid assessment method for confirming the success of the model. This model successfully simulates a closed-head, mild traumatic brain injury without the need for scalp incision or skull opening, provide a more accurate representation of the impact scenario observed in human cases.The avoidance of scalp incision helps to prevent inflammatory responses that may not align with the active situation. Mild traumatic brain injury lacks subjective and accurate diagnostic methods. In the future, our laboratory will continue to explore possible biomolecular markers and their deep molecular mechanisms, and help to transform the obtained molecular markers into clinical and forensic identification practices.

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

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.

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

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Research

JoVE Journal

Neuroscience

Experimental Set Up to Create a Rat Model of Mild Traumatic Brain Injury (mTBI)

Experimental Set Up to Create a Rat Model of Mild Traumatic Brain Injury (MTBI)  

To begin, place a 12-centimeter thick sponge with a 35D hardness in an acrylic box, lacking a top cover. Then, cut a sheet of tinfoil and adhere it to the acrylic box with adhesive tape to create a fragile surface capable of supporting the weight of a rat. Also, mark a 10-centimeter long line as the designated location for positioning the rat's head.Using an iron stand, firmly secure a polyvinyl chloride or 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 one meter inside the PVC tube and adjust the position of the guide tube three centimeters above the tin foil.Next, make a helmet from a stainless steel disc. Prepare a wedge-shaped sponge pillow to place under the rat's head. Swiftly position the anesthetized rat on its chest in the tinfoil.Slide the pillow beneath the rat, ensuring its head remains parallel to the foil surface. Align the helmet with the rat's ears, and securely fasten it in place. Confirm that the PVC pipe is directly above the helmet.Then, release the weight and allow it to impact the rat's head resulting in a fall onto the sponge and a 180 degree rotation. Afterwards, position the rat on its back inside a clean cage.

Acute Neurobehavioral Assessments of the Closed-Head Mild Traumatic Brain Injury (mTBI) Rat Model

Acute Neurobehavioral Assessments of the Closed-Head Mild Traumatic Brain Injury (MTBI) Rat Model  

After inducing a mild traumatic brain injury in an anesthetized rat, position it on its back inside a clean cage. Record the duration from when the rat is anesthetized to when it regains the righting reflex. Also record the time it takes for the rat to exhibit its first seeking behavior from the moment of anesthesia.Next place the rat in the center of a circular apparatus with an exit. Measure and record the time it takes for the rat to exit the circle. Then place the rat successively on three beams of varying length each for a duration of one minute.Score the rat on a scale of zero to six, depending on their performance on the beam. mTBI rats exhibited a significantly prolonged recovery from unconsciousness. The seeking behavior increased significantly in the mTBI group during the recovery period.Also, the mTBI rats took longer to exit the circle compared to sham rats. The beam balance test showed a significant injury effect in wide beam tasks indicating balance impairment in mTBI rats 10 minutes post impact. The 2 and 1.5 centimeter wide beams effectively differentiated between sham and mTBI groups in three independent experiments.

Neurobehavior Assessment of the Closed-Head Mild Traumatic Brain Injury (mTBI) Rat Model

Neurobehavior Assessment of the Closed-Head Mild Traumatic Brain Injury (MTBI) Rat Model  

After inducing a mild traumatic brain injury in an anesthetized rat, position it on its back inside a clean cage. Place foam padding beneath the balance beam to reduce the risk of injury to the rats in case of falls during the test. Place an escape box at one end of the beam.Activate the video camera to record the test. Once the animal recovers, position the rats at the other end of the balance beam. Position the rats on the two centimeter wide beam for a series of five consecutive trials.Record the initiation and conclusion of each trial when the rat's nose crosses the starting and finishing lines respectively. Prepare the open field arena, ensuring it is clean and devoid of any prior odor cues. Divide the arena into three distinct zones:a central inner zone, a middle zone, and an outer zone.Place a rat in the center of the open field arena and initiate the timer. Allow the rat to freely explore the arena for a duration of five minutes. After this period, carefully and gently return the rat to its home cage.Quantify the total distance covered by the rat during the five-minute exploration period. Additionally, determine the amount of time the rat spends in the three zones. Ensure that the water maze apparatus is in proper working condition.Place the platform at a depth of 2.5 centimeters below the water surface. Dye the water black and position cues in the four cardinal directions. Establish a monitoring system to record and observe the behavior of the rats.Then introduce the rat into the water maze. If the rat is unable to reach the platform within a two-minute timeframe, gently guide it using a wooden stick. Allow the rat to become accustomed to the maze environment while standing on the platform for a duration of 20 seconds, then remove it.On the sixth day, which is the probe test day, remove the platform from the water maze and position the rat in the same quadrant for a duration of two minutes. Employ the monitoring system to continuously observe and record the rat's behavior. Motor coordination was assessed pre and post-anesthesia or injury using the beam task.At day one post-injury, mTBI rats showed significantly more hindlimb slips compared to shams. However, after two days, hindlimb slips returned to sham levels. All six mTBI rats had more post-impact hindlimb slips with no differences in beam traversal times between mTBI and sham rats.Distance traveled showed no significant differences between sham and mTBI groups. Anxiety-like behavior was evident in mTBI rats at three and seven days post-injury, spending less time in the center zone during the open field test. Morris water maze results indicated impaired spatial learning and memory in mTBI rats.They took longer to find the hidden platform and spent less time searching for the removed platform during the probe trial without differences in swimming speed suggesting no impact on spontaneous locomotor function.

717 Views.  School of Basic Medical Science, Central South University.  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.

Validating Injury Response and Behavioral Assessments in an mTBI Rat Model

Summary