Name: a repetitive concussive head injury model in mice
Uploaded: 2016-10-12T14:00:00
Description: Watch this Scientific Journal Video about A Repetitive Concussive Head Injury Model in Mice at JoVE.com

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 c...

<ol>
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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.

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			<td height="21" style="height:21px;width:216px;">anesthesia machine</td>
			<td style="width:188px;">Eagle Eye Anesthesia, Inc</td>
			<td style="width:137px;">Model 150&#160;</td>
			<td style="width:291px;">anesthesia</td>
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			<td height="63" style="height:63px;width:216px;">Electromagnetic Impactor</td>
			<td style="width:188px;">LeicaBiosystems</td>
			<td style="width:137px;">Impact One Stereotaxic Impactor</td>
			<td>perform impaction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Digital Stereotaxic instrument</td>
			<td style="width:188px;">LeicaBiosystems</td>
			<td style="width:137px;">39462501</td>
			<td>mount mouse and positioning tips</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sicilone rubber-coated metal tip</td>
			<td style="width:188px;">Precision Tool &#38; Engineering, Gainesvill FL</td>
			<td style="width:137px;">custom-made</td>
			<td>impact tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Lithium Ion All-in-One Trimmer</td>
			<td style="width:188px;">WAHL Home Products</td>
			<td style="width:137px;">9854-600</td>
			<td>shave mouse hair</td>
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			<td height="23" style="height:23px;width:216px;">paper clips</td>
			<td style="width:188px;">custom-made</td>
			<td style="width:137px;"></td>
			<td>probe tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cotton tipped applicators</td>
			<td style="width:188px;">MEDLINE</td>
			<td style="width:137px;">MDS202055</td>
			<td>scrub head with saline</td>
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			<td height="21" style="height:21px;">Tissue Tek O.C.T.</td>
			<td style="width:188px;">ASKURA FINETEK USA INC</td>
			<td style="width:137px;">4583</td>
			<td>tissue embedding</td>
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			<td height="21" style="height:21px;width:216px;">anti-GFAP</td>
			<td style="width:188px;">Dako</td>
			<td style="width:137px;">CA93013</td>
			<td>antibody for IHC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">anti Ferritin</td>
			<td style="width:188px;">Sigma</td>
			<td style="width:137px;">F6136</td>
			<td>antibody for IHC</td>
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			<td height="21" style="height:21px;">VECTASTAIN Elite ABC&#160; kit</td>
			<td style="width:188px;">Vector laboratories</td>
			<td style="width:137px;">PK-6100</td>
			<td>IHC detection system</td>
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			<td height="21" style="height:21px;width:216px;">Permount Mounting Medium</td>
			<td style="width:188px;">Fisher Scientific</td>
			<td style="width:137px;">SP15-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aperio XT ScanScope scanner</td>
			<td style="width:188px;">Leica Microsystems Inc,</td>
			<td style="width:137px;"></td>
			<td>slides scanning</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Leica AutoStainer XL</td>
			<td style="width:188px;">Leica the pathology Company</td>
			<td style="width:137px;">ST2010</td>
			<td>H&#38;E staining</td>
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			<td height="21" style="height:21px;width:216px;">DAB&#160;</td>
			<td style="width:188px;">sigma</td>
			<td style="width:137px;">D3939</td>
			<td>IHC detection system</td>
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	</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 ...

The overall goal of this procedure is to set up a repetitive concussive mouse model using a traditional impact system. These mice can help answer key questions in the mild traumatic brain injury, or TBI, modeling field about the impact of concussion on brain function. The main advantage of this technique is that electronic magnet impact system can be simply operated, and the process be controlled for delivering the impacts.Begin by attaching a custom-made silicon rubber-coated metal tip, to an electromagnetic stereotaxic impact device, taking care that the flat bottom of the coated tip is parallel to the surface of the impact device probe tip. Next, place an anesthetized mouse in the prone position on a heating pad, and confirm a lack of response to toe pinch. Then, use a hair trimmer to completely shave the head, and apply ointment to the animal's eyes.When the animal is ready, preset the velocity of the impact device to four meters per second, and the dwell time to 240 milliseconds on the control box. Place a soft heating pad under the animal's body, to keep the body temperature near 39 degrees Celsius. Then, use the blunt end ear bars to mount the mouse in the stereotactic frame in the prone position.Use the Z driver to lower the impact tip close to the mouse's head. Move the X and Y drivers midway to the target coordinates, above the sagittal suture, to adjust the flat impact nine-millimeter diameter tip, taking care that one edge of the impact tip is vertically parallel to an imaginary horizontal line drawn between the two ears. To correctly set the impact depth, first set the X and Y channels on the digital stereotaxic control panel to zero, to make sure that there is no shift of the impact center after switching the tips.Then move the additional probe tip to the impact site of the mouse's brain. Manually adjust the X and Y drivers to move the probe tip to the center of the impact area, and clip a contact sensor to the tail. Use the Z driver to move the impacter down until the probe tip touches the surface of the impact site, and set the Z channel on the stereotaxic control panel to zero.Then, use the X and Y drivers to manually move the impact tip back to the impact area, until the X and Y drivers are zero. Then move the Z drive down until the control panel is showing the Z driver is at 4.00. And move the retract switch on the control box to retract the actuator.Now click the impact switch on the control box to trigger an impact with a deformation depth of four millimeters, and use a timer to measure the time from the impact until the mouse's first breath. Then, transfer the animal to a warm pad with monitoring until it is fully recovered. To set up repetitive injury, give the mice additional injuries on days four, seven, and 10, after the initial injury.An impact on the center of the head causes short-term unconsciousness, as defined by a transient termination of breathing. The brains exhibit normal morphology, with no obvious structural lesions or tissue damage from the impact observed histologically. In response to TBI, astrocytes are known to undergo certain changes, including activation, proliferation, or reactive gliosis.Indeed, in the corpus callosum of repetitive concussive head injury mouse brains, obvious signs of astrocyte activation can still be observed at seven days after the last impact. Further, ferritin immuno-positive cells can be detected in the mouse cortex one day after the last impact, until at least seven days, suggesting that multiple impactions may result in cortical microbleeds. Once mastered, this technique can be completed in 15 minutes, if it is performed properly.While attempting this procedure, it's important to remember to correctly position the impact side of the mouse brain. After its development, this technique paved the way for research in the field of TBI, to explore mild TBI effect, diagnosis and the potential treatment in model athletes. After watching this video, you should have a good understanding of how to set up a repetitive concussive mouse model, using a traditional impact system.

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