Name: a scalable model to study the effects of blunt-force injury in adult zebrafish
Uploaded: 2021-05-31T15:00:00
Description: Watch this Scientific Journal Video about A Scalable Model to Study the Effects of Blunt-Force Injury in Adult Zebrafish at JoVE.com

The authors would like to thank the Hyde lab members for their thoughtful discussions, the Freimann Life Sciences Center technicians for zebrafish care and husbandry, and the University of Notre Dame Optical Microscopy Core/NDIIF for the use of instruments and their services. This work was supported by the Center for Zebrafish Research at the University of Notre Dame, the Center for Stem Cells and Regenerative Medicine at the University of Notre Dame, and grants from National Eye Institute of NIH R01-EY018417 (DRH), the National Science Foundation Graduate Research Fellowship Program (JTH), LTC Neil Hyland Fellowship of Notre Dame (JTH), Sentinels of Freedom Fellowship (JTH), and the Pat Tillman Scholarship (JTH).

Zebrafish were raised and maintained in the Notre Dame Zebrafish facility in the Freimann Life Sciences Center. The methods described in this manuscript were approved by the University of Notre Dame Animal Care and Use Committee.
1. Traumatic brain injury paradigm
<ol>
	<li>Add 1 mL of 2-phenoxyethanol to 1 L of system water (60 mg of Instant Ocean in 1 L of deionized RO water).</li>
	<li>Prepare an aerated recovery tank containing 2 L of system water at room temperature.</li>
	<li>Select th...

<ol>
	<li>Centers for Disease Control and Prevention. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surveillance+Report+of+Traumatic+Brain+Injury-related+Emergency+Department+Visits,+Hospitalizations,+and+Deaths-United+States,+2014.">Surveillance Report of Traumatic Brain Injury-related Emergency Department Visits, Hospitalizations, and Deaths-United States, 2014.</a> Centers for Disease Control and Prevention, U.S. Department of Health and Human Services. , (2019).</li><li>Galgano, 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=Traumatic+brain+injury:+current+treatment+strategies+and+future+endeavors.">Traumatic brain injury: current treatment strategies and future endeavors.</a> Cell transplantation. 26 (7), 1118-1130 (2017).</li><li>Santiago, L. A., Oh, B. C., Dash, P. K., Holcomb, J. 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M., Diaz-Arrastia, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergency+department+evaluation+of+traumatic+brain+injury+in+the+United+States,+2009-2010.">Emergency department evaluation of traumatic brain injury in the United States, 2009-2010.</a> The Journal of Head Trauma Rehabilitation. 31 (6), 379-387 (2016).</li><li>Faul, M., Xu, L., Wald, M., Coronado, V. <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. , (2010).</li><li>Campbell, L. 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Part I: Pathophysiology and biomechanics.</a> Journal of Neurosurgery. 80 (2), 291-300 (1994).</li><li>Mussulini, B. 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=Seizures+induced+by+pentylenetetrazole+in+the+adult+zebrafish:+a+detailed+behavioral+characterization.">Seizures induced by pentylenetetrazole in the adult zebrafish: a detailed behavioral characterization.</a> PloS One. 8 (1), 54515 (2013).</li><li>Kalueff, 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=Towards+a+comprehensive+catalog+of+zebrafish+behavior+1.0+and+beyond.">Towards a comprehensive catalog of zebrafish behavior 1.0 and beyond.</a> Zebrafish. 10 (1), 70-86 (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+injuries.">Animal models of traumatic brain injuries.</a> Nature Reviews Neuroscience. 14, 128-142 (2013).</li><li>Amamoto, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+axolotls+can+regenerate+original+neuronal+diversity+in+response+to+brain+injury.">Adult axolotls can regenerate original neuronal diversity in response to brain injury.</a> eLife. 5, 13998 (2016).</li><li>Yamamoto, S., Levin, H., Prough, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mild,+moderate+and+severe:+terminology+implications+for+clinical+and+experimental+traumatic+brain+injury.">Mild, moderate and severe: terminology implications for clinical and experimental traumatic brain injury.</a> Current Opinion in Neurology. 31 (6), 672-680 (2008).</li><li>Lund, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Moderate+traumatic+brain+injury,+acute+phase+course+and+deviations+in+physiological+variables:+an+observational+study.">Moderate traumatic brain injury, acute phase course and deviations in physiological variables: an observational study.</a> Scandinavian Journal of Trauma Resuscitation and Emergency Medicine. 24, 77 (2016).</li><li>Levin, H., Arrastia, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis,+prognosis,+and+clinical+management+of+mild+traumatic+brain+injury.">Diagnosis, prognosis, and clinical management of mild traumatic brain injury.</a> The Lancet Neurology. 14 (5), 506-517 (2015).</li><li>Ruff, R. 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=Recommendations+for+diagnosing+a+mild+traumatic+brain+injury:+a+National+Academy+of+Neuropsychology+education+paper.">Recommendations for diagnosing a mild traumatic brain injury: a National Academy of Neuropsychology education paper.</a> Archives of Clinical Neuropsychology: The Official Journal of the National Academy of Neuropsychologists. 24 (1), 3-10 (2009).</li><li>Ganz, J., Brand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+neurogenesis+in+fish.">Adult neurogenesis in fish.</a> Cold Spring Harbor Perspectives in Biology. 8 (7), 019018 (2016).</li><li>Grandel, H., Kaslin, J., Ganz, J., Wenzel, I., Brand, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+stem+cells+and+neurogenesis+in+the+adult+zebrafish+brain:+origin,+proliferation+dynamics,+migration+and+cell+fate.">Neural stem cells and neurogenesis in the adult zebrafish brain: origin, proliferation dynamics, migration and cell fate.</a> Developmental Biology. 295, 263-277 (2006).</li><li>Lahne, M., Nagashima, M., Hyde, D. 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Investigations of neurotrauma and associated sequelae have long been centered on traditional non-regenerative rodent models20. Only recently have studies applied various forms of CNS damage to regenerative models9,11,13,14,21. Though insightful, these models are limited by either their use of an injury method uncommonly seen in the huma...

Traumatic brain injuries (TBIs) are a global health crisis and a leading cause of death and disability. In the United States, approximately 2.9 million people experience a TBI each year, and between 2006-2014 mortality due to TBI or TBI sequelae increased by over 50%1. However, TBIs vary in their etiology, pathology, and clinical presentation due largely in part to the mechanism of injury (MOI), which also influences treatment strategies and predicted prognosis2. Though TBIs can result from various MOI, they are predominately the result of either a penetrating or blunt-force trauma. Penetrating traumas represent a small percentage of TBIs and generate a severe and focal injury that is localized to the immediate and surrounding impaled brain regions3. In contrast, blunt-force TBIs are more common in the general population, span a range of severities (mild, moderate, and severe), and produce a diffuse, heterogeneous, and global injury affecting multiple brain regions1,4,5.
Zebrafish (Danio rerio) have been utilized to examine a wide range of neurological insults spanning the central nervous system (CNS)6,7,8,9. Zebrafish also possess, unlike mammals, an innate and robust regenerative response to repair CNS damage10. Current zebrafish trauma models use various injury methods, including penetration, excision, chemical insult, or pressure waves11,12,13,14,15,16. However, each of these methods utilizes an MOI that is rarely experienced by the human population, is not scalable across a range of injury severities, and does not address the heterogeneity or severity-dependent TBI sequela reported after blunt-force TBI. These factors limit the use of the zebrafish model to understand the underlying mechanisms of the pathologies associated with the most common form of TBI in the human population (mild blunt-force injuries).
We aimed to develop a rapid and scalable blunt-force TBI zebrafish model that provides avenues to investigate injury pathology, progression of TBI sequela, and the innate regenerative response. We modified the commonly used rodent Marmarou17 weight drop and applied it to adult zebrafish. This model yields a reproducible range of severities ranging from mild, moderate, to severe. This model also recapitulates multiple facets of human TBI pathology, in a severity-dependent manner, including seizures, edema, subdural and intracerebral hematomas, neuronal cell death, and cognitive deficits, such as learning and memory impairment. Days following injury, pathologies and deficits dissipate, returning to levels resembling undamaged controls. Additionally, this zebrafish model displays a robust proliferation and neuronal regeneration response across the neuroaxis concerning injury severity.
Here, we provide details toward the set up and induction of blunt-force trauma, scoring post-traumatic seizures, assessment of vascular injuries, instructions on preparing brain sections, approaches to quantifying edema, and insight into the proliferative response following injury.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>2-phenoxyethanol</td>
			<td>Sigma Alderich</td>
			<td>77699</td>
			<td></td>
		</tr>
		<tr>
			<td>#00 buckshot</td>
			<td>Remington</td>
			<td>RMS23770</td>
			<td>3.3g weight for sTBI</td>
		</tr>
		<tr>
			<td>#3 buckshot</td>
			<td>Remington</td>
			<td>RMS23776</td>
			<td>1.5g weight for miTBI/moTBI</td>
		</tr>
		<tr>
			<td>#5 Dumont forceps</td>
			<td>WPI</td>
			<td>14098</td>
			<td></td>
		</tr>
		<tr>
			<td>5-ethynyl-2&#8217;-deoxyuridine</td>
			<td>Life Technologies</td>
			<td>A10044</td>
			<td>EdU</td>
		</tr>
		<tr>
			<td>5ml glass vial</td>
			<td>VWR</td>
			<td>66011-063</td>
			<td></td>
		</tr>
		<tr>
			<td>Click-iT EdU Cell Proliferation Kit</td>
			<td>Life Technologies</td>
			<td>C10340</td>
			<td></td>
		</tr>
		<tr>
			<td>CytoOne 12-well plate</td>
			<td>USA Scientific</td>
			<td>CC7682-7512</td>
			<td></td>
		</tr>
		<tr>
			<td>Instant Ocean</td>
			<td>Instant Ocean</td>
			<td>SS15-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Super frost postiviely charged slides</td>
			<td>VWR</td>
			<td>48311-703</td>
			<td></td>
		</tr>
		<tr>
			<td>Super PAP Pen Liquid Blocker</td>
			<td>Ted Pella</td>
			<td>22309</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue freezing medium</td>
			<td>VWR</td>
			<td>15148-031</td>
			<td></td>
		</tr>
	</tbody>
</table>

a scalable model to study the effects of blunt-force injury in adult zebrafish

Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and heterogenous secondary effects. While there is no mechanism to replace or regenerate the lost neurons following a TBI in humans, zebrafish possess the ability to regenerate neurons throughout their body, including the brain. To examine the breadth of pathologies exhibited in zebrafish following a blunt-force TBI and to study the mechanisms underlying the subsequent neuronal regenerative response, we modified the commonly used rodent Marmarou weight drop for the use in adult zebrafish. Our simple blunt-force TBI model is scalable, inducing a mild, moderate, or severe TBI, and recapitulates many of the phenotypes observed following human TBI, such as contact- and post-traumatic seizures, edema, subdural and intracerebral hematomas, and cognitive impairments, each displayed in an injury severity-dependent manner. TBI sequelae, which begin to appear within minutes of the injury, subside and return to near undamaged control levels within 7 days post-injury. The regenerative process begins as early as 48 hours post-injury (hpi), with the peak cell proliferation observed by 60 hpi. Thus, our zebrafish blunt-force TBI model produces characteristic primary and secondary injury TBI pathologies similar to human TBI, which allows for investigating disease onset and progression, along with the mechanisms of neuronal regeneration that is unique to zebrafish.

Preparing the injury-induction rig allows for a rapid and simplistic means of delivering a scalable blunt-force TBI to adult zebrafish. The graded severity of the injury model provides several easily identifiable metrics of successful injury, though the vascular injury is one of the easiest and most prominent pathologies (Figure 3). The strain of fish used during the injury can make this indicator easier or harder to identify. When using wild-type AB fish(WTAB, <...

Watch this Scientific Journal Video about A Scalable Model to Study the Effects of Blunt-Force Injury in Adult Zebrafish at JoVE.com

A Scalable Model to Study the Effects of Blunt-Force Injury in Adult Zebrafish

We modified the Marmarou weight drop model for adult zebrafish to examine a breadth of pathologies following blunt-force traumatic brain injury (TBI) and the mechanisms underlying subsequent neuronal regeneration. This blunt-force TBI model is scalable, induces a mild, moderate, or severe TBI, and recapitulates injury heterogeneity observed in human TBI.

Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and ...

This protocol provides a simple, rapid, and reproducible method to induce a scalable blunt force traumatic brain injury in adult zebrafish. The adult zebrafish that undergo this blunt force traumatic brain injury exhibit many of the characteristics observed in humans that suffer from a blunt force TBI. Demonstrating the procedure will be Mr.James Hentig and Ms.Kaylee Cloghessy, two doctoral students from my laboratory.Begin by filling a Petri dish with modeling clay. Then use fingers or the back of a pair of forceps to create a raised platform with additional modeling clay. Divide the raised platform lengthwise into two approximately equal halves using a razor blade.Form the two halves into a channel, such that it accommodates the length of an adult fish. Use additional clay to build walls to secure 2/3 of the fish body with the head exposed. Mold a small support in the exposed head region perpendicular to the walls to avoid rotation or recoil of the head upon injury.Ensure that the channel's sides do not impede the dropped weight. Use a mini hole punch to create a 3-millimeter steel disc from a 22-gauge steel flashing. Place an anesthetized fish unresponsive to tail pinch on the clay mold within the channel with its dorsal side up so that its body is secured on the sides.Place the 3-millimeter 22-gauge steel disc on the head, centered over the desired impact point. Align the fish perpendicularly to avoid its head from tilting to one side, which could cause an uneven impact. Use a standard ring stand and arm clamp to secure the steel or plastic tubing, ensuring it is straight, so the bottom of the tubing is 1.5 centimeters above the head of the zebrafish.Look down the tubing to ensure it is aligned above the steel plate. Choose the appropriate ball bearing based on the desired severity of injury. Drop the ball bearing from a predetermined height down the tubing onto the steel plate.Then place the injured fish in the recovery tank to be monitored. Fill a Petri dish with modeling clay and create a small cavity to support the body during dissection. Place the fish in the clay mold with the dorsal side up.Place two dissection pins, one through the midline halfway down the body and the other around 5 millimeters behind the base of the head. Use a pair of 5 Dumont forceps to bluntly sever the optic nerve and remove the eyes. Place one end of the 5 forceps under the right parietal plate.Make a deliberate scissor action moving toward the rostral end and remove the right frontal plate. Then rotate the fish 90 degrees clockwise. Place one end of the 5 forceps under the left parietal plate and use the same scissor motion to remove the left parietal and frontal plates, exposing the entire dorsal aspect of the brain.Use the 5 forceps to bluntly transect the maxilla such that the olfactory bulbs are preserved and not damaged. Using the same forceps, remove the right opercle, preopercle, interopercle, and subopercle. Then bluntly resect the musculature at the caudal end of the calvarium to expose the spinal cord.Using the forceps, bluntly transect the spinal cord. Place the forceps carefully under the brain and gently remove the brain from the calvarium. Dissect the whole brain or region of interest using the instructions in the text manuscript, and place the brain immediately on a small weigh boat using fine forceps, taking care not to stab or scrape the brain.Transfer the brain to the tared drying weigh boat and record the wet weight of the brain. Orient the brains to lay them flat on the weigh boat with the dorsal side facing up. Then place the brain and the drying weigh boat in a hybridization oven set to 60 degrees Celsius for eight hours.To transfer the brain to a new tared small weigh boat once it is dry, pinch the fine forceps together and, starting at the ventral side of the brain, scoop in an upward motion. Make a partial incision on a wet sponge. Place one fish at a time in the opening with the ventral side up and use a 30-gauge needle to inject approximately 40 microliters of 10 millimolar EdU into the fish's body.Then return the fish to the holding tank filled with system water. Collect the brains as mentioned previously, and place them as a group in a 9-milliliter glass vial containing 2 milliliters of nine parts 100%ethanol to one part 37%formaldehyde. Fix the brains at 4 degrees Celsius on a rocker platform.Use a cryostat chuck to embed the brains in TFM in the desired orientation on dry ice. Vascular injury was found to be one of the easiest and most prominent pathologies to identify successful injury via this model. The ability to identify the indicator changed with the strain of fish used during injury.Identification of vascular injury in wild type AB was difficult to distinguish between either mild or moderate TBI and undamaged control fish due to the pigmentation. Following injury, the mild TBI fish displayed minimal surface abrasions, while the moderate TBI fish exhibited limited cerebral hemorrhaging. The extent of the injury was apparent in severe TBI fish.In contrast, vascular injury can be easily identified when using albino or Casper fish. Swelling of the cerebrum due to injury was assessed using edema. In contrast, both moderate TBI and severe TBI had significant edema, 1 dpi and 3 dpi, but fluid content of both moderate TBI and severe TBI returned to levels resembling undamaged controls by 5 dpi.This blunt force injury resulted in a robust cell proliferation response spanning the neuroaxis. Increased EdU labeling was observed in the ventricular and subventricular zones of the forebrain compared to undamaged controls. The injured brains displayed increased EdU labeling in the periventricular gray zone, the optical tectal lobes, and aspects of the anterior hypothalamus compared to the undamaged fish brain.Following severe TBI, neurogenic regions in the hindbrain exhibited increased cell proliferation as compared to the undamaged brain. For proper induction of the injury, ensure the fish are secured and stable in the mold, and that the tubing is straight to avoid off-center impact or alter the weight drop trajectory. This procedure provides a rapid and cost-effective blunt force injury induction method applied to a regenerative model that would be especially applicable for repeated head trauma or injury-induced regenerative studies.

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Neuroscience

An Optic Nerve Crush Injury Murine Model to Study Retinal Ganglion Cell Survival

Injury to the optic nerve can lead to axonal degeneration, followed by a gradual death of retinal ganglion cells (RGCs), which results in irreversible vision loss. Examples of such diseases in human include traumatic optic neuropathy and optic nerve degeneration in glaucoma. It is characterized by typical changes in the optic nerve head, progressive optic nerve degeneration, and loss of retinal ganglion cells, if uncontrolled, leading to vision loss and blindness.
The optic nerve crush (ONC) injury mouse model is an important experimental disease model for traumatic optic neuropathy, glaucoma, etc. In this model, the crush injury to the optic nerve leads to gradual retinal ganglion cells apoptosis. This disease model can be used to study the general processes and mechanisms of neuronal death and survival, which is essential for the development of therapeutic measures. In addition, pharmacological and molecular approaches can be used in this model to identify and test potential therapeutic reagents to treat different types of optic neuropathy.
Here, we provide a step by step demonstration of (I) Baseline retrograde labeling of retinal ganglion cells (RGCs) at day 1, (II) Optic nerve crush injury at day 4, (III) Harvest the retinae and analyze RGC survival at day 11, and (IV) Representative result.

This protocol shows how to retrogradely label retinal ganglion cells, and how to subsequently make an optic nerve crush injury in order to analyze retinal ganglion cell survival and apoptosis. It is an experimental disease model for different types of optic neuropathy, including glaucoma.

Injury to the optic nerve can lead to axonal degeneration, followed by a gradual death of retinal ganglion cells (RGCs), which results in irreversible ...

Micromanipulation of Gene Expression in the Adult Zebrafish Brain Using Cerebroventricular Microinjection of Morpholino Oligonucleotides

Manipulation of gene expression in tissues is required to perform functional studies. In this paper, we demonstrate the cerebroventricular microinjection (CVMI) technique as a means to modulate gene expression in the adult zebrafish brain. By using CVMI, substances can be administered into the cerebroventricular fluid and be thoroughly distributed along the rostrocaudal axis of the brain. We particularly focus on the use of antisense morpholino oligonucleotides, which are potent tools for knocking down gene expression in vivo. In our method, when applied, morpholino molecules are taken up by the cells lining the ventricular surface. These cells include the radial glial cells, which act as neurogenic progenitors. Therefore, knocking down gene expression in the radial glial cells is of utmost importance to analyze the widespread neurogenesis response in zebrafish, and also would provide insight into how vertebrates could sustain adult neurogenesis response. Such an understanding would also help the efforts for clinical applications in human neurodegenerative disorders and central nervous system regeneration. Thus, we present the cerebroventricular microinjection method as a quick and efficient way to alter gene expression and neurogenesis response in the adult zebrafish forebrain. We also provide troubleshooting tips and other useful information on how to carry out the CVMI procedure.

In this article, we demonstrate a method for manipulation of gene expression in the ventricular cells of the adult zebrafish telencephalon using antisense morpholino oligonucleotides. We present this method as an efficient and quick protocol that can be used for functional studies in the adult vertebrate brain.

Manipulation of gene expression in tissues is  required to perform functional studies. In this paper, we demonstrate the  cerebroventricular ...

Electrophysiological Recording in the Brain of Intact Adult Zebrafish

Previously, electrophysiological studies in adult zebrafish have been limited to slice preparations or to eye cup preparations and electrorentinogram recordings. This paper describes how an adult zebrafish can be immobilized, intubated, and used for in vivo electrophysiological experiments, allowing recording of neural activity. Immobilization of the adult requires a mechanism to deliver dissolved oxygen to the gills in lieu of buccal and opercular movement. With our technique, animals are immobilized and perfused with habitat water to fulfill this requirement. A craniotomy is performed under tricaine methanesulfonate (MS-222; tricaine) anesthesia to provide access to the brain. The primary electrode is then positioned within the craniotomy window to record extracellular brain activity. Through the use of a multitube perfusion system, a variety of pharmacological compounds can be administered to the adult fish and any alterations in the neural activity can be observed. The methodology not only allows for observations to be made regarding changes in neurological activity, but it also allows for comparisons to be made between larval and adult zebrafish. This gives researchers the ability to identify the alterations in neurological activity due to the introduction of various compounds at different life stages.

This paper describes how an adult zebrafish can be immobilized, intubated, and used for in vivo electrophysiological experiments to allow recordings and manipulation of neural activity in an intact animal.

Previously, electrophysiological studies in adult zebrafish have been limited to slice preparations or to eye cup preparations and electrorentinogram ...

Stab Wound Injury of the Zebrafish Adult Telencephalon: A Method to Investigate Vertebrate Brain Neurogenesis and Regeneration

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular mechanisms involved in zebrafish adult central nervous system (CNS) regeneration and repair, we developed a zebrafish model of adult telencephalic injury.
In this approach, we manually generate an injury by pushing an insulin syringe needle into the zebrafish adult telencephalon. At different post injury days, fish are sacrificed, their brains are dissected out and stained by immunohistochemistry and/or in situ hybridization (ISH) with appropriate markers to observe cell proliferation, gliogenesis, and neurogenesis. The contralateral unlesioned hemisphere serves as an internal control. This method combined for example with RNA deep sequencing can help to screen for new genes with a role in zebrafish adult telencephalon neurogenesis, regeneration, and repair.

To shed light on the cellular and molecular mechanisms of zebrafish adult neurogenesis and regeneration, we developed a protocol for invasive surgery causing mechanical injuries in the zebrafish adult telencephalon and subsequent monitoring of changes in the stabbed hemisphere by immunohistochemistry or in situ hybridization.

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular ...

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems.

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

We describe a protocol for in vivo labeling of olfactory sensory neurons by electroporation and subsequent confocal laser-scanning or multiphoton microscopy to visualize neuronal morphology and its development over time.

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of ...

A Simple Neuronal Mechanical Injury Methodology to Study Drosophila Motor Neuron Degeneration

The degeneration of neurons occurs during normal development and in response to injury, stress, and disease. The cellular hallmarks of neuronal degeneration are remarkably similar in humans and invertebrates as are the molecular mechanisms that drive these processes. The fruit fly, Drosophila melanogaster, provides a powerful yet simple genetic model organism to study the cellular complexities of neurodegenerative diseases. In fact, approximately 70% of disease-associated human genes have a Drosophila homolog and a plethora of tools and assays have been described using flies to study human neurodegenerative diseases. More specifically the neuromuscular junction (NMJ) in Drosophila has proven to be an effective system to study neuromuscular diseases because of the ability to analyze the structural connections between the neuron and the muscle. Here, we report on an in vivo motor neuron injury assay in Drosophila, which reproducibly induces neurodegeneration at the NMJ by 24 h. Using this methodology, we have described a temporal sequence of cellular events resulting in motor neuron degeneration. The injury method has diverse applications and has also been utilized to identify specific genes required for neurodegeneration and to dissect transcriptional responses to neuronal injury.

A Simple Neuronal Mechanical Injury Methodology to Study Drosophila Motor Neuron Degeneration

Here we describe a simple and widely accessible method to injure segmental nerves in Drosophila larvae to visualize and quantify neurodegeneration of motor neurons at the neuromuscular junction (NMJ) of third instar larvae.

The degeneration of neurons occurs during normal development and in response to injury, stress, and disease. The cellular hallmarks of neuronal ...

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 ...

Facial Nerve Surgery in the Rat Model to Study Axonal Inhibition and Regeneration

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial nerve can be manipulated along its entire length, from its intracranial segment to its extratemporal course. There are three primary types of nerve injury used for the experimental study of regenerative properties: nerve crush, transection, and nerve gap. The range of possible interventions is vast, including surgical manipulation of the nerve, delivery of neuroactive reagents or cells, and either central or end-organ manipulations. Advantages of this model for studying nerve regeneration include simplicity, reproducibility, interspecies consistency, reliable survival rates of the rat, and an increased anatomic size relative to murine models. Its limitations involve a more limited genetic manipulation versus the mouse model and the superlative regenerative capability of the rat, such that the facial nerve scientist must carefully assess time points for recovery and whether to translate results to higher animals and human studies. The rat model for facial nerve injury allows for functional, electrophysiological, and histomorphometric parameters for the interpretation and comparison of nerve regeneration. It thereby boasts tremendous potential toward furthering the understanding and treatment of the devastating consequences of facial nerve injury in human patients.

This protocol describes a reproducible approach to facial nerve surgery in the rat model, including descriptions of various inducible patterns of injury.

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial ...

Using Zebrafish Larvae to Study the Pathological Consequences of Hemorrhagic Stroke

Despite being the most severe subtype of stroke with high global mortality, there is no specific treatment for patients with intracerebral hemorrhage (ICH). Modelling ICH pre-clinically has proven difficult, and current rodent models poorly recapitulate the spontaneous nature of human ICH. Therefore, there is an urgent requirement for alternative pre-clinical methodologies for study of disease mechanisms in ICH and for potential drug discovery.
The use of zebrafish represents an increasingly popular approach for translational research, primarily due to a number of advantages they possess over mammalian models of disease, including prolific reproduction rates and larval transparency allowing for live imaging. Other groups have established that zebrafish larvae can exhibit spontaneous ICH following genetic or chemical disruption of cerebrovascular development. The aim of this methodology is to utilize such models to study the pathological consequences of brain hemorrhage, in the context of pre-clinical ICH research. By using live imaging and motility assays, brain damage, neuroinflammation and locomotor function following ICH can be assessed and quantified.
This study shows that key pathological consequences of brain hemorrhage in humans are conserved in zebrafish larvae highlighting the model organism as a valuable in vivo&#160;system for pre-clinical investigation of ICH. The aim of this methodology is to enable the pre-clinical stroke community to employ the zebrafish larval model as an alternative complementary model system to rodents.

Here we present a protocol to quantify brain injury, locomotor deficits and neuroinflammation following bleeding in the brain in zebrafish larvae, in the context of human intracerebral hemorrhage (ICH).

Despite being the most severe subtype of stroke with high global mortality, there is no specific treatment for patients with intracerebral hemorrhage ...

Combining Behavior and EEG to Study the Effects of Mindfulness Meditation on Episodic Memory

Although there has been recent interest in how mindfulness meditation can affect episodic memory as well as brain structure and function, no study has examined the behavioral and neural effects of mindfulness meditation on episodic memory. Here we present a protocol that combines mindfulness meditation training, an episodic memory task, and EEG to examine how mindfulness meditation changes behavioral performance and the neural correlates of episodic memory. Subjects in a mindfulness meditation experimental group were compared to a waitlist control group. Subjects in the mindfulness meditation experimental group spent four weeks training and practicing mindfulness meditation. Mindfulness was measured before and after training using the Five Facet Mindfulness Questionnaire (FFMQ). Episodic memory was measured before and after training using a source recognition task. During the retrieval phase of the source recognition task, EEG was recorded. The results showed that mindfulness, source recognition behavioral performance, and EEG theta power in right frontal and left parietal channels increased following mindfulness meditation training. In addition, increases in mindfulness correlated with increases in theta power in right frontal channels. Therefore, results obtained from combining mindfulness meditation training, an episodic memory task, and EEG reveal the behavioral and neural effects of mindfulness meditation on episodic memory.

Here we present a protocol for combining mindfulness meditation training, an episodic memory task, and EEG to understand the behavioral and neural effects of mindfulness meditation on episodic memory.

Although there has been recent interest in how mindfulness meditation can affect episodic memory as well as brain structure and function, no study has ...