Name: murine model of controlled cortical impact for the induction of traumatic brain injury
Uploaded: 2019-08-16T14:45:00
Description: Watch this Scientific Journal Video about Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury at JoVE.com

This work was supported by National Institutes of Health Grant GM117341 and The American College of Surgeons C. James Carrico Research Fellowship to S.J.S.

All procedures were approved by the Northwestern University Institutional Animal Care and Use Committee. C57BL/6 mice were purchased from the Jackson Laboratory and group housed at a barrier facility at the Center for Comparative Medicine at Northwestern University (Chicago, IL). All animals were housed in 12/12 h light/dark cycle with free access to food and water.
1. Induce anesthesia
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	<li>Anesthetize the mouse with ketamine (125 mg/kg) and xylazine (10 mg/kg) injected intraperitoneal...

<ol>
	<li>Faul, 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> Traumatic Brain Injury in the United States: Emergency Department Visits, Hospitalizations and Deaths 2002-2006. , (2010).</li><li>Roozenbeek, B., Maas, A. I., Menon, D. 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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+outcome+after+rehabilitation+for+severe+traumatic+brain+injury.">Functional outcome after rehabilitation for severe traumatic brain injury.</a> Archives of Physical Medicine and Rehabilitation. 76 (12), 1103-1112 (1995).</li><li>Schwarzbold, 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=Psychiatric+disorders+and+traumatic+brain+injury.">Psychiatric disorders and traumatic brain injury.</a> Neuropsychiatric Disease and Treatment. 4 (4), 797-816 (2008).</li><li>Whelan-Goodinson, R., Ponsford, J., Johnston, L., Grant, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Psychiatric+disorders+following+traumatic+brain+injury:+their+nature+and+frequency.">Psychiatric disorders following traumatic brain injury: their nature and frequency.</a> Journal of Head Trauma Rehabilitation. 24 (5), 324-332 (2009).</li><li>Peskind, E. 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B., Cuda, C. M., Perlman, H., Schwulst, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Role+of+Microglia+in+the+Etiology+and+Evolution+of+Chronic+Traumatic+Encephalopathy.">The Role of Microglia in the Etiology and Evolution of Chronic Traumatic Encephalopathy.</a> Shock. 48 (3), 276-283 (2017).</li><li>Belanger, H. G., Vanderploeg, R. D., McAllister, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subconcussive+Blows+to+the+Head:+A+Formative+Review+of+Short-term+Clinical+Outcomes.">Subconcussive Blows to the Head: A Formative Review of Short-term Clinical Outcomes.</a> Journal of Head Trauma Rehabilitation. 31 (3), 159-166 (2016).</li><li>Carman, A. 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=Expert+consensus+document:+Mind+the+gaps-advancing+research+into+short-term+and+long-term+neuropsychological+outcomes+of+youth+sports-related+concussions.">Expert consensus document: Mind the gaps-advancing research into short-term and long-term neuropsychological outcomes of youth sports-related concussions.</a> Nature Reviews Neurology. 11 (4), 230-244 (2015).</li><li>Kramer, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Contribution+to+the+Theory+of+Cerebral+Concussion.">A Contribution to the Theory of Cerebral Concussion.</a> Annals of Surgery. 23 (2), 163-173 (1896).</li><li>Lighthall, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+cortical+impact:+a+new+experimental+brain+injury+model.">Controlled cortical impact: a new experimental brain injury model.</a> Journal of Neurotrauma. 5 (1), 1-15 (1988).</li><li>Dixon, C. E., Clifton, G. L., Lighthall, J. W., Yaghmai, A. A., Hayes, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+controlled+cortical+impact+model+of+traumatic+brain+injury+in+the+rat.">A controlled cortical impact model of traumatic brain injury in the rat.</a> Journal of Neuroscience Methods. 39 (3), 253-262 (1991).</li><li>Schwulst, S. J., Trahanas, D. M., Saber, R., Perlman, H. <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-induced+alterations+in+peripheral+immunity.">Traumatic brain injury-induced alterations in peripheral immunity.</a> Journal of Trauma and Acute Care Surgery. 75 (5), 780-788 (2013).</li><li>Trahanas, D. M., Cuda, C. M., Perlman, H., Schwulst, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+Activation+of+Infiltrating+Monocyte-Derived+Cells+After+Mild+and+Severe+Traumatic+Brain+Injury.">Differential Activation of Infiltrating Monocyte-Derived Cells After Mild and Severe Traumatic Brain Injury.</a> Shock. 43 (3), 255-260 (2015).</li><li>Makinde, H. M., Cuda, C. M., Just, T. B., Perlman, H. R., Schwulst, S. 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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=Lateral+fluid+percussion+brain+injury:+a+15-year+review+and+evaluation.">Lateral fluid percussion brain injury: a 15-year review and evaluation.</a> Journal of Neurotrauma. 22 (1), 42-75 (2005).</li><li>Marmarou, 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=A+new+model+of+diffuse+brain+injury+in+rats.+Part+I:+Pathophysiology+and+biomechanics.">A new model of diffuse brain injury in rats. Part I: Pathophysiology and biomechanics.</a> Journal of Neurosurgery. 80 (2), 291-300 (1994).</li><li>Reneer, D. V., 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+multi-mode+shock+tube+for+investigation+of+blast-induced+traumatic+brain+injury.">A multi-mode shock tube for investigation of blast-induced traumatic brain injury.</a> Journal of Neurotrauma. 28 (1), 95-104 (2011).</li><li>Ma, X., Aravind, A., Pfister, B. J., Chandra, N., Haorah, J. <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+and+Assessment+of+Injury+Severity.">Animal Models of Traumatic Brain Injury and Assessment of Injury Severity.</a> Molecular Neurobiology. , (2019).</li><li>Makinde, H. 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=Monocyte+depletion+attenuates+the+development+of+posttraumatic+hydrocephalus+and+preserves+white+matter+integrity+after+traumatic+brain+injury.">Monocyte depletion attenuates the development of posttraumatic hydrocephalus and preserves white matter integrity after traumatic brain injury.</a> PLoS One. 13 (11), e0202722 (2018).</li><li>Osier, N. D., Dixon, C. 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There are several steps that are critical for applying a reliable and consistent injury. First, the mouse must reach a deep plane of surgical anesthesia ensuring no movement during the performance of the craniectomy. While numerous anesthetic regimens may be used to induce general anesthesia in rodents, anesthetics that induce respiratory depression such as inhalational anesthetics may result in respiratory arrest when combined with a severe TBI. This protocol utilizes ketamine (125 mg/kg) and xylazine (10 mg/kg) injecte...

The Centers for Disease Control and Injury Prevention estimate that approximately 2 million Americans sustain a traumatic brain injury (TBI) every year1,2. In fact, TBI contributes to over 30% of all injury related deaths in the United States with healthcare costs nearing $80 billion annually and almost $4 million per person per year surviving a severe TBI3,4,5. The impact of TBI is highlighted by the significant long-term neurocognitive and neuropsychiatric complications suffered by its survivors with the insidious onset of behavioral, cognitive, and motor impairments termed Chronic Traumatic Encephalopathy (CTE)6,7,8,9,10. Even subclinical concussive events&#8212;those impacts that do not result in clinical symptoms&#8212;can lead to long-term neurologic dysfunction11,12.
Animal models for the study of TBI have been employed since the late 1800&#8217;s13. In the 1980s, a pneumatic impactor for the purpose of modeling TBI was developed. This method is now referred to as controlled cortical impact (CCI)14. The control and reproducibility of CCI led researchers to adapt the model for use in rodents15. Our laboratory uses this model to induce TBI via a commercially available impactor and electronic actuating device16,17. This model is capable of producing a wide range of clinically applicable TBI states depending on the biomechanical parameters used. Histologic evaluation of TBI brains after a severe injury induced in our laboratory demonstrates significant ipsilateral cortical and hippocampal loss as well as contralateral edema and distortion. Additionally, CCI produces a consistent impairment in motor and cognitive function as measured by behavioral assays18. Limitations to CCI include the need for craniotomy and the expense of acquiring the impactor and actuating device.
Several additional models of TBI exist and are well established in the literature including the lateral fluid percussion model, weight drop model, and blast injury model19,20,21. While each of these models have their own distinct advantages their main drawbacks are mixed injury, high mortality and lack of standardization, respectively22. Furthermore, none of these models offer the accuracy, precision, and reproducibility of CCI. By adjusting the biomechanical parameters input into the actuating device, the CCI model allows the investigator precise control over size of the injury, depth of the injury, and kinetic energy applied to the brain. This gives investigators the ability to apply the entire spectrum of TBI to specific areas of the brain. It also permits the greatest reproducibility from experiment to experiment.

<table>
	<tbody>
		<tr>
			<td>AnaSed Injection Xylazine Sterile Solution</td>
			<td>LLOYD, Inc.</td>
			<td>5939911020</td>
		</tr>
		<tr>
			<td>Buprenorphine SR Lab 0.5mg/mL</td>
			<td>Zoopharm-Wildlife Pharmaceuticals USA</td>
			<td>BSRLAB0.5-182012</td>
		</tr>
		<tr>
			<td>High Speed Rotary Micromotor KiT0</td>
			<td>Foredom Electric Company</td>
			<td>K.1070</td>
		</tr>
		<tr>
			<td>Imapact one for Stereotaxix CCI</td>
			<td>Leica Biosystems Nussloch GmbH</td>
			<td>39463920</td>
		</tr>
		<tr>
			<td>Ketathesia Ketamine HCl Injection USP</td>
			<td>Henry Schein, Inc</td>
			<td>56344</td>
		</tr>
		<tr>
			<td>Mouse Specific Stereotaxic Base</td>
			<td>Leica Biosystems Nussloch GmbH</td>
			<td>39462980</td>
		</tr>
		<tr>
			<td>Trephines for Micro Drill</td>
			<td>Fine Science Tools, Inc</td>
			<td>18004-50</td>
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murine model of controlled cortical impact for the induction of traumatic brain injury

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the United States. In fact, TBI is a contributing factor to over a third of all injury-related mortality. Nonetheless, the cellular and molecular mechanisms underlying the pathophysiology of TBI are poorly understood. Thus, preclinical models of TBI capable of replicating the injury mechanisms pertinent to TBI in human patients are a critical research need. The controlled cortical impact (CCI) model of TBI utilizes a mechanical device to directly impact the exposed cortex. While no model can full recapitulate the disparate injury patterns and heterogeneous nature of TBI in human patients, CCI is capable of inducing a wide range of clinically applicable TBI. Furthermore, CCI is easily standardized allowing investigators to compare results across experiments as well as across investigative groups. The following protocol is a detailed description of applying a severe CCI with a commercially available impacting device in a murine model of TBI.

The impactor mounts directly on the stereotaxic frame allowing for as much as 10 &#181;m resolution for control of the point of impact, depth and penetration. The electromagnetic forces employed can impart impact velocities ranging 1.5&#8211;6 m/s. This allows for unparalleled precision and reproducibility over the entire range of clinically relevant TBI. Investigators can run pilot experiments changing the injury parameters such as impactor tip size, impact velocity, and impact depth to determine the parameters that bes...

Watch this Scientific Journal Video about Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury at JoVE.com

Murine Model of Controlled Cortical Impact for the Induction of Traumatic Brain Injury

Here we describe a protocol for the induction of murine traumatic brain injury via an open-head controlled cortical impact.

The Centers for Disease Control and Injury Prevention estimate that almost 2 million people sustain a traumatic brain injury (TBI) every year in the ...

Controlled cortical impact is easy to standardize across subjects and experiments and allows for the application of the entire spectrum of traumatic brain injury to precisely defined regions of the brain. Demonstrating this procedure is Mecca Islam, a research technician in my laboratory. This technique remains the most consistent and reproducible form of inducing traumatic brain injury in rodents.Before beginning the procedure, attach the impacting device to the stereotaxic operating frame. Se the actuating device with the desired biomechanical parameters for the appropriate experimental velocity and well time. Don new personal protective equipment and sterile gloves and confirm a lack of response to toe pinch in the anesthetized experimental mouse.Use clippers to shave the fur for the surgical site and apply ointment to the animal's eyes. Then place the mouse into the operating theater and prep the shaved skin with three sequential iodine based and alcohol surgical scrubs. To induce a controlled cortical traumatic brain injury, first use a scalpel to make a one centimeter incision along the midline of the scalp to expose the skull.Retract the scalp from the operative site and identify the sagittal and coronal sutures on the exposed skull. To perform a craniectomy, equip a microdrill with a five millimeter trephine drill bit to activate the drill at maximum speed and apply the bit perpendicular to the skull two millimeters to the left of the sagittal suture and two millimeters rostral to the coronal suture with gentle even pressure. A slight give will be felt when the drill penetrates the skull.Use forceps and a small gauge hypodermic needle to remove the bone flap, fully exposing the underlying dura mater and rotate the impacter tip into the operative field. Secure the bilateral temporal bones between the miniature ear bars of the stereotaxic frame and lock the incisors within the incisor clamp to create a stable three point hold on the mouse head. Lower the tip until it makes contact with the exposed dura mater.The contact sensor of the instrument will make an audible tone to alert that contact has been made. Retract the impacting tip from the zero point and lower the impacter position on the stereotaxic frame to set the desired impact depth. Then active the impacter on the actuating device before rotating the device back out of the field to allow the animal to be removed from the frame.Immediately after the injury, apply direct pressure from a sterile cotton tipped applicator to the skull and injured cortical surface to control any bleeding and use a fresh applicator to dry the skull. Close the scalp over the craniectomy according to standard techniques and administer postoperative analgesia. Then place the animal in the lateral decubitus recovery position in a clean pre-warmed cage with monitoring until full recumbency and measure the body weight every three days throughout the course of the experiment.Delivery of the injury as demonstrated results in a subdural intraparenchymal and subarachnoid hemorrhage. Histologic evaluation of traumatic brain injury brain tissue sections after severe injury reveals a significant ipsilateral cortical and hippocampal loss as well as contralateral edema and distortion. MR imaging of severely injured brains also demonstrates progressive tissue loss and replacement by cerebra-spinal fluid.Controlled cortical impact induces a reliable and consistent injury that is capable of producing a wide range of clinically applicable brain injuries. Our controlled cortical impact method generates a murine model of severe traumatic brain injury for behavioral and imaging analysis and produces tissue for molecular and cellular analysis.

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Neuroscience

Lateral Fluid Percussion: Model of Traumatic Brain Injury in Mice

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and mortality. Based on the nature of primary injury following TBI, complex and heterogeneous secondary consequences result, which are followed by regenerative processes 1,2. Primary injury can be induced by a direct contusion to the brain from skull fracture or from shearing and stretching of tissue causing displacement of brain due to movement 3,4. The resulting hematomas and lacerations cause a vascular response 3,5, and the morphological and functional damage of the white matter leads to diffuse axonal injury 6-8. Additional secondary changes commonly seen in the brain are edema and increased intracranial pressure 9. Following TBI there are microscopic alterations in biochemical and physiological pathways involving the release of excitotoxic neurotransmitters, immune mediators and oxygen radicals 10-12, which ultimately result in long-term neurological disabilities 13,14. Thus choosing appropriate animal models of TBI that present similar cellular and molecular events in human and rodent TBI is critical for studying the mechanisms underlying injury and repair.
Various experimental models of TBI have been developed to reproduce aspects of TBI observed in humans, among them three specific models are widely adapted for rodents: fluid percussion, cortical impact and weight drop/impact acceleration 1. The fluid percussion device produces an injury through a craniectomy by applying a brief fluid pressure pulse on to the intact dura. The pulse is created by a pendulum striking the piston of a reservoir of fluid. The percussion produces brief displacement and deformation of neural tissue 1,15. Conversely, cortical impact injury delivers mechanical energy to the intact dura via a rigid impactor under pneumatic pressure 16,17. The weight drop/impact model is characterized by the fall of a rod with a specific mass on the closed skull 18. Among the TBI models, LFP is the most established and commonly used model to evaluate mixed focal and diffuse brain injury 19. It is reproducible and is standardized to allow for the manipulation of injury parameters. LFP recapitulates injuries observed in humans, thus rendering it clinically relevant, and allows for exploration of novel therapeutics for clinical translation 20.
We describe the detailed protocol to perform LFP procedure in mice. The injury inflicted is mild to moderate, with brain regions such as cortex, hippocampus and corpus callosum being most vulnerable. Hippocampal and motor learning tasks are explored following LFP.

Lateral fluid percussion (LFP), an established model of traumatic brain injury in mice, is demonstrated. LFP fulfills three major criteria for animal models: validity, reliability and clinical relevance. The procedure, consisting of surgical craniotomy, fixation of hub followed by induction of injury, resulting in focal and diffuse injuries, is described.

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and ...

Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury

Traumatic Brain Injury (TBI) afflicts more than 1.7 million people in the United States each year and even mild TBI can lead to persistent neurological impairments 1. Two pervasive and disabling symptoms experienced by TBI survivors, memory deficits and a reduction in seizure threshold, are thought to be mediated by TBI-induced hippocampal dysfunction 2,3. In order to demonstrate how altered hippocampal circuit function adversely affects behavior after TBI in mice, we employ lateral fluid percussion injury, a commonly used animal model of TBI that recreates many features of human TBI including neuronal cell loss, gliosis, and ionic perturbation 4-6.
	Here we demonstrate a combinatorial method for investigating TBI-induced hippocampal dysfunction. Our approach incorporates multiple ex vivo physiological techniques together with animal behavior and biochemical analysis, in order to analyze post-TBI changes in the hippocampus. We begin with the experimental injury paradigm along with behavioral analysis to assess cognitive disability following TBI. Next, we feature three distinct ex vivo recording techniques: extracellular field potential recording, visualized whole-cell patch-clamping, and voltage sensitive dye recording. Finally, we demonstrate a method for regionally dissecting subregions of the hippocampus that can be useful for detailed analysis of neurochemical and metabolic alterations post-TBI.
	These methods have been used to examine the alterations in hippocampal circuitry following TBI and to probe the opposing changes in network circuit function that occur in the dentate gyrus and CA1 subregions of the hippocampus (see Figure 1). The ability to analyze the post-TBI changes in each subregion is essential to understanding the underlying mechanisms contributing to TBI-induced behavioral and cognitive deficits. 
	The multi-faceted system outlined here allows investigators to push past characterization of phenomenology induced by a disease state (in this case TBI) and determine the mechanisms responsible for the observed pathology associated with TBI.

A multi-faceted approach to investigating functional changes to hippocampal circuitry is explained. Electrophysiological techniques are described along with the injury protocol, behavioral testing and regional dissection method. The combination of these techniques can be applied in similar fashion for other brain regions and scientific questions.

Traumatic Brain Injury (TBI) afflicts more than 1.7 million people in the United States each year and even mild TBI can lead to persistent neurological ...

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 ...

Induction of Diffuse Axonal Brain Injury in Rats Based on Rotational Acceleration

Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large percentage of TBI patients requiring hospitalization. DAI involves widespread axonal damage from shaking, rotation or blast injury, leading to rapid axonal stretch injury and secondary axonal changes that are associated with a long-lasting impact on functional recovery. Historically, experimental models of DAI without focal injury have been difficult to design. Here we validate a simple, reproducible and reliable rodent model of DAI that causes widespread white matter damage without skull fractures or contusions.

This protocol validates a reliable, easy-to-perform and reproducible rodent model of brain diffuse axonal injury (DAI) that induces widespread white matter damage without skull fractures or contusions.

Traumatic brain injury (TBI) is a major cause of death and disability. Diffuse axonal injury (DAI) is the predominant mechanism of injury in a large ...

Systems Analysis of the Neuroinflammatory and Hemodynamic Response to Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a significant public health problem. Repeated exposure to mTBI can lead to cumulative, long-lasting functional deficits. Numerous studies by our group and others have shown that mTBI stimulates cytokine expression and activates microglia, decreases cerebral blood flow and metabolism, and impairs cerebrovascular reactivity. Moreover, several works have reported an association between derangements in these neuroinflammatory and hemodynamic markers and cognitive impairments. Herein we detail methods to characterize the neuroinflammatory and hemodynamic tissue response to mTBI in mice. Specifically, we describe how to perform a weight-drop model of mTBI, how to longitudinally measure cerebral blood flow using a non-invasive optical technique called diffuse correlation spectroscopy, and how to perform a Luminex multiplexed immunoassay on brain tissue samples to quantify cytokines and immunomodulatory phospho-proteins (e.g., within the MAPK and NF&#954;B pathways) that respond to and regulate activity of microglia and other neural immune cells. Finally, we detail how to integrate these data using a multivariate systems analysis approach to understand the relationships between all of these variables. Understanding the relationships between these physiologic and molecular variables will ultimately enable us to identify mechanisms responsible for mTBI.

This protocol presents methods to characterize the neuroinflammatory and hemodynamic response to mild traumatic brain injury and to integrate these data as part of a multivariate systems analysis using partial least squares regression.

Mild traumatic brain injuries (mTBIs) are a significant public health problem. Repeated exposure to mTBI can lead to cumulative, long-lasting functional ...

A Metric Test for Assessing Spatial Working Memory in Adult Rats Following Traumatic Brain Injury

Impairments to sensory, short-term, and long-term memory are common side effects after traumatic brain injury (TBI). Due to the ethical limitations of human studies, animal models provide suitable alternatives to test treatment methods, and to study the mechanisms and related complications of the condition. Experimental rodent models have historically been the most widely used due to their accessibility, low cost, reproducibility, and validated approaches. A metric test, which tests the ability to recall the placement of two objects at various distances and angles from one another, is a technique to study impairment in spatial working memory (SWM) after TBI. The significant advantages of metric tasks include the possibility of dynamic observation, low cost, reproducibility, relative ease of implementation, and low stress environment. Here, we present a metric test protocol to measure impairment of SWM in adult rats after TBI. This test provides a feasible way to evaluate physiology and pathophysiology of brain function more effectively.

Traumatic brain injury (TBI) is commonly associated with memory impairment. Here, we present a protocol to assess spatial working memory after TBI via a metric task. A metric test is a useful tool to study spatial working memory impairment after TBI.

Impairments to sensory, short-term, and long-term memory are common side effects after traumatic brain injury (TBI). Due to the ethical limitations 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 ...