This works was supported by funding from a Florida Health grant (Brain and spinal cord injury research fund) (KKW).

All procedures were performed under protocols #201207692 approved by the Institutional Animal Care and Use Committee of University of Florida and in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals.
1. Animal Care
<ol>
	<li>Use 3&#8211;4-month-old male C57BL/6J mice. Provide bedding, nesting material, food, and water ad libitum. Keep the mice in ambient temperatures controlled at 20 - 22 &#176;C with constant 12-hr light/12-hr dark cycles.</li>
</ol>
2. Pre-impaction Preparation
<ol>
	<li>Attach a custom-made silicone rubber-coated metal tip to an electromagnetic stereotaxic impact device. Make sure the flat bottom of the tip is parallel to the surface of the probe tip (Figure 1A).</li>
	<li>Anesthetize the mouse with 4% isoflurane followed by maintenance anesthesia of 2.5% isoflurane. Check the anesthesia via the flow meter. Monitor the anesthesia level until the animal reaches a surgical level of anesthesia by showing loss of pedal withdrawal reflex.</li>
	<li>Put the mouse in a prone position on a heating pad. Use a funnel-shaped nose cone to keep the mouse under anesthesia. Completely shave the head using a trimmer. Use petrolatum ophthalmic ointment on the mouse&#39;s eyes to prevent dryness while under anesthesia.</li>
</ol>
3. Impact Parameters Setting
NOTE: The impact system includes a control box to set impact parameters, an actuator to perform the impaction, and a digital stereotactic frame with 3-movement axes.

<ol>
	<li>Pre-set the velocity of the impact device to 4 m/sec and dwell time to 240 msec on the control box.</li>
</ol>
4. Positioning the Impact Center
<ol>
	<li>Put a soft heating pad under the animal&#39;s body to keep the body temperature near 39 &#176;C. Mount the mouse in a stereotactic frame in a prone position with the blunt-end ear bars.</li>
	<li>Lower the impact tip close to the mouse&#39;s head by moving the Z-driver. Adjust the flat impact tip (9 mm diameter) by moving the X- and Y-drivers midway to the target coordinates above the sagittal suture.</li>
	<li>Make sure one edge of the impact tip is vertically parallel to an imaginary horizontal line drawn between the two ears (Figure 1C). The center of impact corresponds to the central sagittal suture midway between interfrontal and lambdoid sutures (interaural 9 mm to interaural 0 mm, lateral 4.5 mm).</li>
</ol>
5. Impact Depth Setting
<ol>
	<li>To correctly set the impact depth, use additional probe tip to replace the insulated silicone rubber-coated impact tip.</li>
	<li>To make sure there is no shift of the impact center after switching tips, set the X and Y channel on the digital stereotaxic control panel to zero before switching the tips.</li>
	<li>Move the probe tip to the center of the impact area by manually moving the X-and Y-drives.</li>
	<li>Clip contact sensor to the mouse&#39;s tail.</li>
	<li>Move the impactor (Z drive) down until the probe tip touches the surface of the impact site.</li>
	<li>Set the Z channel on the stereotaxic control panel to zero.</li>
	<li>Move the impact tip back to the impact area by manually adjusting X- and Y-drivers (NOT the zero buttons on the digital stereotaxic control panel) until X- and Y-drivers are zero (where the impact tip was previously positioned).</li>
	<li>Retract the actuator by moving the retract switch on the control box. Manually move the impactor down (Z driver) by 4 mm.</li>
</ol>
6. Impact
<ol>
	<li>Trigger the impact by clicking the impact switch on the control box and achieve a deformation depth of 4 mm.</li>
</ol>
7. Post-impaction
<ol>
	<li>Measure the time from the impact until the mouse&#39;s first breath using a timer.</li>
	<li>Remove the animal from the instrument and place them on a warm pad to maintain their body temperature. Do not leave the animal unattended until it has regained sufficient consciousness to maintain sternal recumbency.</li>
	<li>Allow for recovery before returning the animal back into a clean cage. Do not return an animal to the company of other animals until fully recovered.</li>
	<li>Observe and weigh the mice daily. If the mice show signs of pain, intraperitoneally inject them with Meloxicam at 1 - 2 mg/kg every 12 - 24 hr.</li>
</ol>
8. Repetitive Impaction
<ol>
	<li>Give the mice additional injuries on days 4, 7, and 10 after the initial injury (72 hr interval between impacts).</li>
</ol>
9. Immunohistochemistry (IHC)
<ol>
	<li>Transcardial perfusion
	<ol>
		<li>Anesthetize the mice via intraperitoneal injection with 200 m/kg pentobarbital.</li>
		<li>Assess and assure surgical-plane anesthesia by a toe pinch. Secure the mouse in the supine position by gently taping the forepaws and hind paws to a Styrofoam work surface inside a chemical fume hood.</li>
		<li>Make an incision through the skin along the thoracic midline from just beneath the xiphoid process to the clavicle. Make two additional skin incisions at the xiphoid process and proceed along the base of the ventral ribcage laterally.</li>
		<li>Open the thoracic cavity and expose the heart by cutting through the thoracic musculature and ribcage.</li>
		<li>Secure the beating heart with blunt forceps and make a 1 - 2 mm incision in the left ventricle.</li>
		<li>Immediately insert a butterfly needle into the right atrium. Begin the infusion of 20ml saline by pushing the syringe slowly.</li>
		<li>Switch from saline to 4% paraformaldehyde. Continue perfusion with 20ml of paraformaldehyde.</li>
		<li>Decapitate the mouse and remove the skin with scissors. Isolate the brain from the skull using a bone cutter.</li>
	</ol>
	</li>
	<li>Cryostat sectioning
	<ol>
		<li>Embed brain tissues in optimum cutting temperature (O.C.T.) formulation and freeze at -80 &#176;C. Place the brain in the cryostat in a sagittal orientation. Cut brain sections 5 &#181;m thick.</li>
	</ol>
	</li>
	<li>Staining
	<ol>
		<li>Dry the frozen sections at room temperature for 1 hr.</li>
		<li>Incubate the slides with 100 &#956;l of 2% goat serum and 0.1% Triton X-100 in phosphate buffered saline (PBS) for 1 hr at RT.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides with anti-GFAP (1:200) or anti-ferritin antibody (1:200) separately over night at 4 &#176;C.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides for 2 hr at room temperature with biotin-conjugated secondary antibody.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate the slides with avidin-biotin complex (ABC) solution (1:50) at room temperature for 30 min.</li>
		<li>Wash the slides 3 times with 300 &#956;l of PBS. Then incubate in 3,3&#8242;-diaminobenzidine (DAB) substrate solution (50 ml PBS, 10 &#181;l H2O2, 10 mg DAB pill, filter before using) for 5 - 8 min. Observe the slides under the microscope until the positive cells appear.</li>
		<li>Rinse the slides in slow running tap water for 5 min. Clean slides with a lab-wipe. Then mount the sections with mounting medium and coverslip.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Baugh, C. M., 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=Chronic+traumatic+encephalopathy:+neurodegeneration+following+repetitive+concussive+and+subconcussive+brain+trauma.">Chronic traumatic encephalopathy: neurodegeneration following repetitive concussive and subconcussive brain trauma.</a> Brain Imaging Behav. 6 (2), 244-254 (2012).</li><li>McKee, A. C., 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=Chronic+traumatic+encephalopathy+in+athletes:+progressive+tauopathy+after+repetitive+head+injury.">Chronic traumatic encephalopathy in athletes: progressive tauopathy after repetitive head injury.</a> J. Neuropathol Exp Neurol. 68 (7), 709-735 (2009).</li><li>Petraglia, A. L., Dashnaw, M. L., Turner, R. C., Bailes, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+of+mild+traumatic+brain+injury:+translation+of+physiological+and+anatomic+injury.">Models of mild traumatic brain injury: translation of physiological and anatomic injury.</a> Neurosurgery. 75 Suppl (4), S34-S49 (2014).</li><li>Goldstein, L. E., McKee, A. C., Stanton, P. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Considerations+for+animal+models+of+blast-related+traumatic+brain+injury+and+chronic+traumatic+encephalopathy.">Considerations for animal models of blast-related traumatic brain injury and chronic traumatic encephalopathy.</a> Alzheimers Res Ther. 6 (5), 64 (2014).</li><li>Gold, E. M., 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=Functional+assessment+of+long-term+deficits+in+rodent+models+of+traumatic+brain+injury.">Functional assessment of long-term deficits in rodent models of traumatic brain injury.</a> RegenMed. 8 (4), 483-516 (2013).</li><li>Xiong, Y., Mahmood, A., Chopp, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+traumatic+brain+injury.">Animal models of traumatic brain injury.</a> Nat Rev Neurosci. 14 (2), 128-142 (2013).</li><li>Luo, 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=Long-term+cognitive+impairments+and+pathological+alterations+in+a+mouse+model+of+repetitive+mild+traumatic+brain+injury.">Long-term cognitive impairments and pathological alterations in a mouse model of repetitive mild traumatic brain injury.</a> Front Neurol. , 5-12 (2014).</li><li>Yang, Z., 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=Temporal+MRI+characterization,+neurobiochemical+and+neurobehavioral+changes+in+a+mouse+repetitive+concussive+head+injury+model.">Temporal MRI characterization, neurobiochemical and neurobehavioral changes in a mouse repetitive concussive head injury model.</a> Sci Rep. 10 (5), 11178 (2015).</li><li>Zhang, 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=Inhibition+of+monoacylglycerol+lipase+prevents+chronic+traumatic+encephalopathy-like+neuropathology+in+a+mouse+model+of+repetitive+mild+closed+head+injury.">Inhibition of monoacylglycerol lipase prevents chronic traumatic encephalopathy-like neuropathology in a mouse model of repetitive mild closed head injury.</a> J Cereb Blood Flow Metab. 35 (3), 443-453 (2015).</li><li>Petraglia, A. 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=The+spectrum+of+neurobehavioral+sequelae+after+repetitive+mild+traumatic+brain+injury:+a+novel+mouse+model+of+chronic+traumatic+encephalopathy.">The spectrum of neurobehavioral sequelae after repetitive mild traumatic brain injury: a novel mouse model of chronic traumatic encephalopathy.</a> J Neurotrauma. 31 (13), 1211-1224 (2014).</li><li>Lumpkins, K. M., Bochicchio, G. V., Keledjian, K., Simard, J. M., McCunn, M., Scalea, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+fibrillary+acidic+protein+is+highly+correlated+with+brain+injury.">Glial fibrillary acidic protein is highly correlated with brain injury.</a> J Trauma. 65 (4), 778-782 (2008).</li><li>Yang, Z., Wang, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+fibrillary+acidic+protein:+from+intermediate+filament+assembly+and+gliosis+to+neurobiomarker.">Glial fibrillary acidic protein: from intermediate filament assembly and gliosis to neurobiomarker.</a> Trends Neurosci. 38 (6), 364-374 (2015).</li><li>Liu, 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=Increased+expression+of+ferritin+in+cerebral+cortex+after+human+traumatic+brain+injury.">Increased expression of ferritin in cerebral cortex after human traumatic brain injury.</a> Neurol Sci. 34 (7), 1173-1180 (2013).</li><li>Jordan, B. D., 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+clinical+spectrum+of+sport-related+traumatic+brain+injury.">The clinical spectrum of sport-related traumatic brain injury.</a> Nat Rev Neurol. 9 (4), 222-230 (2013).</li></ol>

The authors have no financial interest to disclose.

To mimic brain injuries morphologically similar to the clinical condition, post-concussion symptoms are expected. Post-concussion symptoms generally include headaches, dizziness, vertigo, fatigue, memory and sleeping problems, trouble concentrating as well as anxiety, and depressed mood. Since somatic symptoms may not yet be measurable in animal models, the changes of motor and cognitive function and emotional behavior are used as criteria for rationally evaluating concussion in animal models. In a previous reported stud...

Concussion, also called mild traumatic brain injury (mTBI), is the most frequent occurrence of traumatic brain injury (TBI) and affects millions of people in United States. Concussions can be tricky to diagnose and there is no specific cure for concussion. There is a growing recognition and some evidence that mild mechanical trauma resulting from sports injuries, military combat, and other physically engaging pursuits may have cumulative and chronic neurological consequences1,2. However, there is still a lack of knowledge regarding concussions and their effects. Current methodology restricts the studies of pathology and treatment in humans since only neurologic assessment and imaging evaluation are available for clinical diagnosis. Animal models provide a means to study concussions in an efficient, rigorous, and controlled manner with the hope of further diagnosis and treatment of mTBI.
Studies have adapted traditional TBI models such as controlled cortical impact (CCI), fluid-percussion impact (FPI), weight drop injury, and blast injury to perform mTBI and stimulate low injury severities by changing the injury parameters. These models are beneficial to use due to their ability to replicate brain trauma morphologically similar to the clinical condition; however, they also have their own limitations. The severity of injury induced by an acceleration injury (weight drop) is often highly variable. The two results of the mild CCI &#8212; subarachnoid hemorrhage and focal contusion &#8212; are not comparable with typical human concussions. CCI and FPI require a craniotomy, which is not clinically relevant, while blast injury is a more controversial model in regards to the different exposure position and peak pressure measurements as well as variable secondary injury during the exposure3-6. An updated concussive animal model that can translate pre-clinical research into the clinical setting is necessary in research.
The key issue in modeling mild TBI is to define the experimental injury severity, which most closely replicates the injury in a clinical setting. Recently, different research groups developed the closed head injury or concussive head injury (CHI) model7-10. CHI is a modification of CCI without a craniotomy, but it still uses a traditional electronic magnetic impact system to generate a head impact. A CHI can induce a concussion ranging from mild to moderate by adjusting the impact parameters. Loss of consciousness (LOC) can be observed immediately after an impact by detecting a decrease in the breathing rate or the transient termination of breathing. The period of LOC is used to determine the severity of injury. This paper includes a slightly improved and updated version of a repetitive CHI (rCHI) model in mice, along with a detailed step-by-step protocol and representative results. The rCHI model research strategies are beneficial in determining mTBI effects and potential treatments, especially since there is no individual animal model capable of imitating all of the concussion-induced pathological changes.

<table><tbody><tr><td>anesthesia machine</td><td>Eagle Eye Anesthesia, Inc</td><td>Model 150&amp;nbsp;</td><td>anesthesia</td></tr><tr><td>Electromagnetic Impactor</td><td>LeicaBiosystems</td><td>Impact One Stereotaxic Impactor</td><td>perform impaction</td></tr><tr><td>Digital Stereotaxic instrument</td><td>LeicaBiosystems</td><td>39462501</td><td>mount mouse and positioning tips</td></tr><tr><td>Sicilone rubber-coated metal tip</td><td>Precision Tool &amp;amp; Engineering, Gainesvill FL</td><td>custom-made</td><td>impact tip</td></tr><tr><td>Lithium Ion All-in-One Trimmer</td><td>WAHL Home Products</td><td>9854-600</td><td>shave mouse hair</td></tr><tr><td>paper clips</td><td>custom-made</td><td></td><td>probe tip</td></tr><tr><td>Cotton tipped applicators</td><td>MEDLINE</td><td>MDS202055</td><td>scrub head with saline</td></tr><tr><td>Tissue Tek O.C.T.</td><td>ASKURA FINETEK USA INC</td><td>4583</td><td>tissue embedding</td></tr><tr><td>anti-GFAP</td><td>Dako</td><td>CA93013</td><td>antibody for IHC</td></tr><tr><td>anti Ferritin</td><td>Sigma</td><td>F6136</td><td>antibody for IHC</td></tr><tr><td>VECTASTAIN Elite ABC&amp;nbsp; kit</td><td>Vector laboratories</td><td>PK-6100</td><td>IHC detection system</td></tr><tr><td>Permount Mounting Medium</td><td>Fisher Scientific</td><td>SP15-100</td><td></td></tr><tr><td>Aperio XT ScanScope scanner</td><td>Leica Microsystems Inc,</td><td></td><td>slides scanning</td></tr><tr><td>Leica AutoStainer XL</td><td>Leica the pathology Company</td><td>ST2010</td><td>H&amp;amp;E staining</td></tr><tr><td>DAB&amp;nbsp;</td><td>sigma</td><td>D3939</td><td>IHC detection system</td></tr></tbody></table>

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.

In this model (Figure 1 A-C), there were brief periods of gasping and shallow respirations. A loss of consciousness (unconscious) is defined as a decrease in the breathing rate or transient termination of breathing before resuming a normal respiration. An impact on the center of the head caused short-term unconsciousness (7.5 &#177; 4.7, 7.8 &#177; 5.5, 10.2 &#177; 8.8, 9.5 &#177; 8.0 sec at each impact separately, Figure 1D). Mouse brains showed normal m...

Watch this Scientific Journal Video about A Repetitive Concussive Head Injury Model in Mice at JoVE.com

A Repetitive Concussive Head Injury Model in Mice

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-repetitive-concussive-head-injury-model-in-mice

Research

JoVE Journal

Medicine

11.9K Views.  University of Florida. 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.

Video: A Repetitive Concussive Head Injury Model in Mice

The Spared Nerve Injury (SNI) Model of Induced Mechanical Allodynia in Mice

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared nerve injury (SNI) model induces symptoms of neuropathic pain such as mechanical allodynia i.e. pain due to tactile stimuli that do not normally provoke a painful response [1]. 
The SNI mouse model involves ligation of two of the three branches of the sciatic nerve (the tibial nerve and the common peroneal nerve), while the sural nerve is left intact [2]. The lesion results in marked hypersensitivity in the lateral area of the paw, which is innervated by the spared sural nerve. The non-operated side of the mouse can be used as a control. The advantages of the SNI model are the robustness of the response and that it doesn&#x2019;t require expert microsurgical skills.
The threshold for mechanical pain response is determined by testing with von Frey filaments of increasing bending force, which are repetitively pressed against the lateral area of the paw [3], [4]. A positive pain reaction is defined as sudden paw withdrawal, flinching and/or paw licking induced by the filament. A positive response in three out of five repetitive stimuli is defined as the pain threshold. 
As demonstrated in the video protocol, C57BL/6 mice experience profound allodynia as early as the day following surgery and maintain this for several weeks.

The Spared Nerve Injury SNI Model of Induced Mechanical Allodynia in Mice

The Spared Nerve Injury animal model is described here as a mouse model of peripheral neuropathic pain following partial denervation of the sciatic nerve by lesioning the tibial and common peroneal nerve branches, leaving the remaining sural nerve intact. Behavioral modification resulting from mechanical allodynia is quantified by von Frey filaments.

Peripheral neuropathic pain is a severe chronic pain condition which may result from trauma to sensory nerves in the peripheral nervous system. The spared ...

Controlled Cervical Laceration Injury in Mice

Use of genetically modified mice enhances our understanding of molecular mechanisms underlying several neurological disorders such as a spinal cord injury (SCI). Freehand manual control used to produce a laceration model of SCI creates inconsistent injuries often associated with a crush or contusion component and, therefore, a novel technique was developed. Our model of cervical laceration SCI has resolved inherent difficulties with the freehand method by incorporating 1) cervical vertebral stabilization by vertebral facet fixation, 2) enhanced spinal cord exposure, and 3) creation of a reproducible laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm in depth without associated contusion. Compared to the standard methods of creating a SCI laceration such as freehand use of a scalpel or scissors, our method has produced a consistent lesion. This method is useful for studies on axonal regeneration of corticospinal, rubrospinal, and dorsal ascending tracts.

A novel technique to create a reproducible in vivo model of cervical spinal cord laceration injury in the mouse is described. This technique is based on spine stabilization by fixation of the cervical facets and laceration of the spinal cord using an oscillating blade with an accuracy of &plusmn;0.01 mm.

Use of genetically modified mice enhances our  understanding of molecular mechanisms underlying several neurological disorders  such as a spinal cord ...

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 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 ...

A Novel and Translational Rat Model of Concussion Combining Force and Rotation with In Vivo Cerebral Microdialysis

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to altered neurotransmission. Indeed, cerebral microdialysis studies in rodents have demonstrated an excessive extracellular glutamate release in the hippocampus within the first 10 min following trauma. Microdialysis offers the clear advantage of in vivo neurotransmitter continuous sampling while not having to sacrifice the animal. In addition to the aforementioned technique, a closed head injury model that exerts rapid acceleration and deceleration of the head and torso is needed, as such a factor is not available in many other animal models. The Wayne State weight-drop model mimics this essential component of human craniocerebral trauma, allowing the induction of an impact on the head of an unrestrained rodent with a falling weight. Our novel and translational rat model combines cerebral microdialysis with the Wayne State weight-drop model to study, in lightly anesthetized and unrestrained adult rats, the acute changes in extracellular neurotransmitter levels following concussion. In this protocol, the microdialysis probe was inserted inside the hippocampus as region of interest, and was left inserted in the brain at impact. There is a high density of terminals and receptors in the hippocampus, making it a relevant region to document altered neurotransmission following concussion. When applied to adult Sprague-Dawley rats, our combined model induced increases in hippocampal extracellular glutamate concentrations within the first 10 min, consistent with the previously reported post-concussion symptomology. This combined weight-drop model provides a reliable tool for researchers to study early therapeutic responses to concussions in addition to repetitive brain injury, since this protocol induces a closed-head mild trauma.

Neurotransmitter alteration is a mechanism of neural dysfunction that occurs after concussion and contributes to the sometimes-catastrophic long-term consequences. This rat model combines microdialysis, allowing in vivo neurotransmitter quantification, with a weight-drop technique exerting rapid acceleration and deceleration of the head and torso, an important factor of human craniocerebral trauma.

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to ...

Neuroscience

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 ...

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 ...

Modeling Repetitive Concussive Head Injuries in a Mouse Model

<a href='https://app-jove-com.bdigitaluss.remotexs.co/v/54530/a-repetitive-concussive-head-injury-model-in-mice'>Source: Yang, Z., et.al.&#160;A Repetitive Concussive Head Injury Model in Mice. J. Vis. Exp. (2016).</a>This video demonstrates the induction of repetitive concussive head injuries in a mouse using an electromagnetic impact device. The procedure involves positioning the impact tip between the interfrontal and lambdoid sutures on the skull of an anesthetized mouse and using a probe tip to precisely set the impact depth. The impact is delivered at a controlled velocity and depth to simulate mild traumatic brain injuries, followed by a recovery period, with the injuries repeated at specified intervals.

Source: Yang, Z., et.al.&#160;A Repetitive Concussive Head Injury Model in Mice. J. Vis. Exp. (2016).This video demonstrates the induction of repetitive ...