This work was supported by National Institutes of Health grant, R01 AG033620 (BG) and by Robert Draper Technology Innovation Funding (DAW).

1. Construction of the HIT Device&#160;
<ol>
	<li>Attach the spring to the board using two clamps and four screws (Figure 1A). Center the clamps relative to the width of the board and butt them up against one another with the outer clamp flush with the edge of the board. Prior to attaching the clamps, bend them using pliers to fit tightly over the spring. 
	NOTE: See Table 1 for descriptions of the materials required for constructing the HIT device.&#160;The clamped end of the spring should be 1/8 inch (3.2 mm) from the edge of the board, and the free end should extend over the board by 3/4 inch (19 mm). Adjust the spring so that it lies parallel with the length of the board.</li>
	<li>Wrap the free end of the spring once around with the adhesive strip of Velcro loops. The outer edge of the Velcro should be flush with the end of the spring. The Velcro is important because it is used to secure the vial to the spring by creating a tight compression fitting. The Velcro also permits easy connection and removal of vials, allowing many vials to be processed in a short period of time.</li>
	<li>Place the ice bucket cover upside down, centered, tight against the wooden board. Orient the raised region of the ice bucket cover such that the long edge is parallel to the width of the board. Note that the raised region of the ice bucket is 1/2 inch (13&#160;mm)&#160;higher than the wooden board, so that when a vial is attached to the spring the spring will not lie flat on the board.</li>
	<li>Slide the whole device against a fixed object such as a wall, so that the ice bucket cover is wedged between the board and the object and does not move.</li>
	<li>Tape the paper protractor to the bottom of a cardboard fly vial tray and stand it on edge against the length of the board so that the 90&#176; mark is aligned with the spring when it is pulled back to a perfectly vertical position.</li>
</ol>
2. Operation of the HIT Device
<ol>
	<li>Place between 1 and 60 CO2-anesthetized flies in an empty vial and stopper the vial using a tight-fitting cotton ball.</li>
	<li>Confine the flies to the bottom 1 inch (2.5 cm) of the vial by pushing the cotton ball into the vial until it is 1 inch (2.5 cm)&#160;from the bottom. It is helpful to draw a line on the vial at the 1&#160;inch (2.5 cm)&#160;mark. Note that confining flies to larger or smaller regions of the vial can affect the severity of phenotypes.</li>
	<li>Wait 5 min for the flies to recover mobility from the CO2. Note that it is not known whether 5 min is sufficient to completely remove the effects of CO2.</li>
	<li>Insert the end of the spring into the vial until the inner edge of the Velcro is flush with the top of the vial (Figure 1B). When the spring is lying flat, 1 inch (2.5 cm)&#160;of the vial should overlap the raised region of the ice bucket cover. Vials can be reused many times.</li>
	<li>While sitting, hold the vial at the Velcro region using the thumb and forefinger of your left hand. Hold the board tight to the benchtop using your right hand. Alternatively, use C-clamps to hold the board tight to the benchtop.</li>
	<li>Pull the spring perfectly straight back to the desired angle. Release the spring. Allow the spring to come to a complete stop.</li>
	<li>Remove the vial from the spring and allow the flies to recover for &#8805;5 min. Subject the flies to another strike or transfer the flies to a vial with fly food. 
	NOTE: A variety of assays can be used to evaluate the phenotypic effects of strikes from the HIT device. For example, effects on longevity can be determined by analyzing the percent of flies that survive at times after injury, effects on brain morphology can be determined by histological analysis of the head, and effects on gene expression can be determined by quantitative analysis of mRNA levels10.</li>
	<li>Determine effects of the procedure that are not due to strikes by identically treating control flies that are not subjected to strikes. Wear hearing protection because the impact of the vial against the ice bucket cover produces a loud noise.</li>
</ol>

<ol>
	<li>Harrison-Felix, C. L., Whiteneck, G. G., Jha, A., DeVivo, M. J., Hammond, F. M., Hart, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mortality+over+four+decades+after+traumatic+brain+injury+rehabilitation:+A+retrospective+cohort+study.">Mortality over four decades after traumatic brain injury rehabilitation: A retrospective cohort study.</a> Arch Phys Med Rehabil. 90, 1506-1513 (2009).</li><li>Coronado, V. G., 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=Surveillance+for+traumatic+brain+injury-related+deaths+&#8211;+United+States.">Surveillance for traumatic brain injury-related deaths &#8211; United States.</a> MMWR Surveill Summ. 60, 1-32 (1997).</li><li>Masel, B., DeWitt, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+brain+injury:+A+disease+process,+not+an+event.">Traumatic brain injury: A disease process, not an event.</a> J. Neurotrauma. 27, 1529-1540 (2010).</li><li>Blennow, K., Hardy, J., Zetterberg, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neuropathology+and+neurobiology+of+traumatic+brain+injury.">The neuropathology and neurobiology of traumatic brain injury.</a> Neuron. 76, 886-899 (2012).</li><li>Prins, M., Greco, T., Alexander, D., Giza, C. 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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unique+challenges+in+clinical+trails+in+traumatic+brain+injury.">Unique challenges in clinical trails in traumatic brain injury.</a> Crit Care Med. 37, S129-S135 (2009).</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> Nature Rev Neurosci. 14, 128-142 (2013).</li><li>Balsiger, Z., Leudkte, J., Mawer, S., Willey, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> HIT device high speed analysis. , (2014).</li><li>Davceva, N., Janevska, V., Illevski, B., Petrushevska, G., Popeska, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+occurrence+of+acute+subdural+haematoma+and+diffuse+axonal+injury+as+two+typical+acceleration+injuries.">The occurrence of acute subdural haematoma and diffuse axonal injury as two typical acceleration injuries.</a> J Forensic Leg Med. 19, 480-484 (2012).</li><li>Katzenberger, R. J., Loewen, C. A., Wassarman, D. R., Petersen, A. J., Ganetzky, B., Wassarman , D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Drosophila.+model+of+closed+head+traumatic+brain+injury.">A Drosophila. model of closed head traumatic brain injury.</a> Proc Natl Acad Sci USA. 110, E4152-E4159 (2013).</li><li>Fang, Y., Bonini, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axon+degeneration+and+regeneration:+insights+from+Drosophila+.models+of+nerve+injury.">Axon degeneration and regeneration: insights from Drosophila .models of nerve injury.</a> Annu Rev Cell Biol. 28, 575-597 (2012).</li><li>Babcock, D. T., Ganetzky, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+method+for+accurate+and+rapid+measurement+of+flight+performance+in+Drosophila.">An improved method for accurate and rapid measurement of flight performance in Drosophila.</a> J Vis Exp. (84), e51223 (2014).</li><li>Tully, T., Preat, T., Boynton, S. C., Vecchio, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+dissection+of+consolidated+memory+in+Drosophila.">Genetic dissection of consolidated memory in Drosophila.</a> Cell. 79, 35-47 (1994).</li><li>Andretic, R., Shaw, P. 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We have no conflicts of interest to disclose.

The HIT device method is distinguished from other methods that inflict traumatic injury in flies&#160;by the fact that it causes closed head rather than penetrating TBI11. Furthermore, the HIT device method takes less time, effort, and skill to inflict TBI in many flies, so the method is more amenable than other methods to large-scale genetic screens. Lastly, the fact that primary injuries inflicted by the HIT device are not limited to the brain is both a limitation and an advantage. It is a limitation because...

An author's name was corrected in the publication of <a href="http://www.jove.com/video/52905">A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila</a>. The second to last author's was spelled incorrectly. It has been updated from:
Barry Ganetky
to:
Barry Ganetzky

An author's name was corrected in the publication of <a href="http://www.jove.com/video/52905">A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila</a>.

Erratum: A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Traumatic brain injury (TBI) is defined as injury to the brain from an external mechanical force. Most commonly, TBI results from closed head forces such as blunt forces and inertial acceleration and deceleration forces that cause the brain to strike the inside of the skull. In the United States, it is estimated that 50,000 individuals die each year from TBI and 2.5-6.5 million individuals are living with the consequences of TBI, including debilitating physical, cognitive, and behavioral problems1,2. The consequences of TBI are not only due to primary mechanical injuries to the brain but also to secondary cellular and molecular injuries to the brain as well as other tissues that occur over time3-5. The development of approaches to diagnose and treat TBI has proven to be difficult because TBI is a complex disease process. The variable nature of primary injuries, human physiology, and environmental factors results in heterogeneous secondary injuries and pathologies. Underlying variable factors include the severity of the primary injury, the time between repetitive primary injuries, and the age and genotype of the individual. Understanding how each variable factor contributes to the consequences of TBI is likely to aid in the development of approaches to diagnose and treat TBI6,7.
Here we describe a method for inflicting closed head TBI in Drosophila melanogaster (fruit flies) that can be used to delineate the contribution of variable factors to the consequences of TBI. The method is based on an initial observation that intensely hitting the side of a fly culture vial against the palm of a hand caused wild-type flies to become temporarily incapacitated, a likely consequence of TBI. Thus, we constructed the High-Impact Trauma (HIT) device to recapitulate the acceleration and deceleration forces from the hand-hitting action. A high-speed movie shows that a single strike from the HIT device causes flies to contact the vial wall several times with their head and body8. To some extent, all contacts are likely to cause the fly brain to ricochet and deform against the head capsule, similar to what happens to humans in falls and car crashes9. Accordingly, flies treated with the HIT device display phenotypes consistent with brain injury, including temporary incapacitation followed by ataxia, gradual recovery of mobility, gene expression changes in the head, and progressive neurodegeneration in the brain10. Thus, the HIT device makes it possible to study TBI using the enormous arsenal of experimental tools and techniques developed for flies.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Zinc plated compression spring</td>
			<td>The Hillman&#160; Group</td>
			<td>540189</td>
			<td>9 7/8 in (length), 15/16 in (outer diameter), 0.12 in (wire size)</td>
		</tr>
		<tr>
			<td>Wooden board</td>
			<td></td>
			<td></td>
			<td>9 in (length), 6.5 in (width), 0.75 in (height)</td>
		</tr>
		<tr>
			<td>Clamps</td>
			<td>Sigma Electrical Manufacturing Corporation</td>
			<td>49822</td>
			<td>3.10 in (length), 0.68 in (width), 1.11 in (height), EMT Two Hole Straps, click on type for 1 inch steel EMT conduit</td>
		</tr>
		<tr>
			<td>Loop half of self-adhesive velcro</td>
			<td></td>
			<td></td>
			<td>3 in (length), (3/4 in width)</td>
		</tr>
		<tr>
			<td>Polyurethane ice bucket cover</td>
			<td>Fisher Scientific</td>
			<td>02-591-45</td>
			<td>9 1/8 in (length), 9 1/8 in (width), 1 1/4 in (height)</td>
		</tr>
		<tr>
			<td>Plastic fly vials</td>
			<td>Applied Scientific</td>
			<td>AS-510</td>
			<td>3 11/16 in (height), 1 1/16 in (inner diameter), 1 1/8 in (outer diameter)</td>
		</tr>
		<tr>
			<td>Large cotton balls</td>
			<td>Fisher Scientific</td>
			<td>22-456-883</td>
			<td></td>
		</tr>
		<tr>
			<td>Paper protractor</td>
			<td></td>
			<td></td>
			<td>10 in (diameter)</td>
		</tr>
	</tbody>
</table>

a method to inflict closed head traumatic brain injury in drosophila

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies using Drosophila have contributed important breakthroughs in understanding neurological processes. Thus, with the goal of understanding the cellular and molecular basis of TBI pathologies in humans, we developed the High Impact Trauma (HIT) device to inflict closed head TBI in flies. Flies subjected to the HIT device display phenotypes consistent with human TBI such as temporary incapacitation and progressive neurodegeneration. The HIT device uses a spring-based mechanism to propel flies against the wall of a vial, causing mechanical damage to the fly brain. The device is inexpensive and easy to construct, its operation is simple and rapid, and it produces reproducible results. Consequently, the HIT device can be combined with existing experimental tools and techniques for flies to address fundamental questions about TBI that can lead to the development of diagnostics and treatments for TBI. In particular, the HIT device can be used to perform large-scale genetic screens to understand the genetic basis of TBI pathologies.

We are interested in understanding why flies die shortly after primary injury. To quantify death, we determined the Mortality Index at 24 hr (MI24), which is the percentage of flies that died within 24 hr of the primary injury. Flies subjected to strikes from the HIT device were incubated at 25 &#176;C in a vial with fly food, and the number of dead flies was counted after 24 hr. We used this approach to identify factors that affect the MI24 and found that the MI24 is not affected by the ...

Watch this Scientific Journal Video about A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila at JoVE.com

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Here we describe a method to inflict closed head traumatic brain injury (TBI) in Drosophila. This method provides a gateway to investigate the cellular and molecular mechanisms that underlie TBI pathologies using the vast array of experimental tools and techniques available for flies.

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies ...

a-method-to-inflict-closed-head-traumatic-brain-injury-in-drosophila

Research

JoVE Journal

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11.3K Views.  University of Wisconsin-Madison. Here we describe a method to inflict closed head traumatic brain injury (TBI) in Drosophila. This method provides a gateway to investigate the cellular and molecular mechanisms that underlie TBI pathologies using the vast array of experimental tools and techniques available for flies.

Video: A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

A Novel Method to Model Chronic Traumatic Encephalopathy in Drosophila

Chronic Traumatic Encephalopathy (CTE) is an established neurodegenerative disease that is closely associated with exposure to repetitive mild Traumatic Brain Injury (mTBI). The mechanisms responsible for its complex pathological changes remain largely elusive, despite a recent consensus to define the neuropathological criteria. Here, we describe a novel method to develop a model of CTE in Drosophila melanogaster&#160;(Drosophila&#160;)&#160;in an attempt to identify the key genes and pathways that lead to the characteristic hyperphosphorylated tau accumulation and neuronal death in the brain. Adjustable-strength impacts to inflict mild closed injury are delivered directly to the fly head, subjecting the head to rapid acceleration and deceleration. Our method eliminates the potential problems inherent with other Drosophila mTBI models (e.g.,animal death might be induced by damage to other parts of the body or to internal organs). The less labor- and cost-intensive animal care, short life span, and extensive genetic tools make the fruit fly ideal to study CTE pathogenesis and make it possible to perform large-scale, genome-wide forward genetic and pharmacological screens. We anticipate that the ongoing characterization of the model will generate important mechanistic insights on disease prevention and therapeutic approaches.

A Novel Method to Model Chronic Traumatic Encephalopathy in Drosophila

Here, we describe a new approach to inflict closed-head traumatic brain injury in Drosophila melanogaster. Our method has the advantage of directly delivering repetitive impacts with adjustable strength to the head alone. Further exploration of the invertebrate system will help to illuminate the pathogenesis of chronic traumatic encephalopathy.

Chronic Traumatic Encephalopathy (CTE) is an established neurodegenerative disease that is closely associated with exposure to repetitive mild Traumatic ...

A Novel In Vitro Model of Blast Traumatic Brain Injury

Traumatic brain injury is a leading cause of death and disability in military and civilian populations. Blast traumatic brain injury results from the detonation of explosive devices, however, the mechanisms that underlie the brain damage resulting from blast overpressure exposure are not entirely understood and are believed to be unique to this type of brain injury. Preclinical models are crucial tools that contribute to better understand blast-induced brain injury. A novel in vitro blast TBI model was developed using an open-ended shock tube to simulate real-life open-field blast waves modelled by the Friedlander waveform. C57BL/6N mouse organotypic hippocampal slice cultures were exposed to single shock waves and the development of injury was characterized up to 72 h using propidium iodide, a well-established fluorescent marker of cell damage that only penetrates cells with compromised cellular membranes. Propidium iodide fluorescence was significantly higher in the slices exposed to a blast wave when compared with sham slices throughout the duration of the protocol. The brain tissue injury is very reproducible and proportional to the peak overpressure of the shock wave applied.

A Novel In Vitro Model of Blast Traumatic Brain Injury

This paper describes a novel model of primary blast traumatic brain injury. A compressed-air driven shock tube is used to expose in vitro mouse hippocampal slice cultures to a single shock wave. This is a simple and rapid protocol generating a reproducible brain tissue injury with a high throughput.

Traumatic brain injury is a leading cause of death and disability in military and civilian populations. Blast traumatic brain injury results from the ...

Effects of Blast-induced Neurotrauma on Pressurized Rodent Middle Cerebral Arteries

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral vascular effects. Impact (i.e., non-blast) traumatic brain injury (TBI) is known to decrease pressure autoregulation in the cerebral vasculature in both humans and experimental animals. The hypothesis that blast-induced traumatic brain injury (bTBI), like impact TBI, results in impaired cerebral vascular reactivity was tested by measuring myogenic dilatory responses to reduced intravascular pressure in rodent middle cerebral arterial (MCA) segments from rats subjected to mild bTBI using an Advanced Blast Simulator (ABS) shock tube. Adult, male Sprague-Dawley rats were anesthetized, intubated, ventilated and prepared for Sham bTBI (identical manipulation and anesthesia except for blast injury) or mild bTBI. Rats were randomly assigned to receive Sham bTBI or mild bTBI followed by sacrifice 30 or 60 min post-injury. Immediately after bTBI, righting reflex (RR) suppression times were assessed, euthanasia at the time points post-injury was completed, the brain was harvested and the individual MCA segments were collected, mounted and pressurized. As the intraluminal pressure perfused through the arterial segments was reduced in 20 mmHg increments from 100 to 20 mmHg, MCA diameters were measured and recorded. With decreasing intraluminal pressure, MCA diameters steadily increased significantly above baseline in the Sham bTBI groups while MCA dilator responses were significantly reduced (p &#60; 0.05) in both bTBI groups as evidenced by the impaired, smaller MCA diameters recorded for the bTBI groups. In addition, RR suppression in the bTBI groups was significantly (p &#60; 0.05) higher than in the Sham bTBI groups. MCA&#39;s collected from the Sham bTBI groups exhibited typical vasodilatory properties to decreases in intraluminal pressure while MCA&#39;s collected following bTBI exhibited significantly impaired myogenic vasodilatory responses to reduced pressure that persisted for at least 60 min after bTBI.

Here, we present a protocol to describe methods for ex vivo vascular reactivity determination following a primary blast traumatic brain injury (bTBI) using isolated, pressurized, rodent middle cerebral arterial (MCA) segments. bTBI induction is accomplished using a shock tube, also known as an Advanced Blast Simulator (ABS) device.

Though there have been studies on the histopathological and behavioral effects of blast exposure, fewer have been dedicated to blast&#39;s cerebral ...

Investigating Alterations in Caecum Microbiota After Traumatic Brain Injury in Mice

Increasing evidence shows that the microbiota-gut-brain axis plays an important role in the pathogenesis of brain diseases. Several studies also demonstrate that traumatic brain injuries cause changes to the gut microbiota. However, mechanisms underlying the bidirectional regulation of the brain-gut axis remain unknown. Currently, few models exist for studying the changes in gut microbiota after traumatic brain injury. Therefore, the presented study combines protocols for inducing traumatic brain injury using a lateral fluid percussion device and analysis of caecum samples following injury for investigating alterations in the gut microbiome. Alterations of the gut microbiota composition after traumatic brain injury are determined using 16S-rDNA sequencing. This protocol provides an effective method for studying the relationships between enteric microorganisms and traumatic brain injury.

Presented here is a protocol to induce diffuse traumatic brain injury using a lateral fluid percussion device followed by the collection of the caecum content for gut microbiome analysis.

Increasing evidence shows that the microbiota-gut-brain axis plays an important role in the pathogenesis of brain diseases. Several studies also ...

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 ...

Intravital Imaging of Fluorescent Protein Expression in Mice with a Closed-Skull Traumatic Brain Injury and Cranial Window Using a Two-Photon Microscope

The goal of this protocol is to demonstrate how to longitudinally visualize the expression and localization of a protein of interest within specific cell types of an animal's brain, upon exposure to exogenous stimuli. Here, the administration of a closed-skull traumatic brain injury (TBI) and simultaneous implantation of a cranial window for subsequent longitudinal intravital imaging in mice is shown. Mice are intracranially injected with an adeno-associated virus (AAV) expressing enhanced green fluorescent protein (EGFP) under a neuronal specific promoter. After 2 to 4 weeks, the mice are subjected to a repetitive TBI using a weight drop device over the AAV injection location. Within the same surgical session, the mice are implanted with a metal headpost and then a glass cranial window over the TBI impacting site. The expression and cellular localization of EGFP is examined using a two-photon microscope in the same brain region exposed to trauma over the course of months.

This study demonstrates delivery of a repetitive traumatic brain injury to mice and simultaneous implantation of a cranial window for subsequent intravital imaging of a neuron-expressed EGFP using two-photon microscopy.

The goal of this protocol is to demonstrate how to longitudinally visualize the expression and localization of a protein of interest within specific cell ...

Validating Injury Response and Behavioral Assessments in an mTBI Rat Model

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 

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 ...