We are indebted to the University of Utah zebrafish facility for animal husbandry. R.I.D. was supported by NIH R56NS053897, and L.K.B. was a predoctoral trainee supported by the HHMI Med-Into-Grad initiative.

Zebrafish were raised and bred according to standard procedures; experiments were approved by the University of Utah Institutional Animal Care and Use Committee.
1. Preparation of Surgery Plates
<ol>
	<li>Make surgery plates using 60 mm Petri dishes and Sylgard 184 Silicone Elastomer Kit, following manufacturer&#8217;s instructions. Fill dishes no more than half-full and allow to polymerize. Store covered at room temperature.</li>
</ol>
2. Preparation of Micropipettes
<ol>
	<li>Fabricate micropipettes by heating and pulling thin-wall borosilicate capillary tubing in a micropipette puller using the same settings for making microinjection needles.</li>
	<li>Under a dissection microscope, snap off tip of micropipette to approximately 200 &#181;m in diameter with forceps.</li>
	<li>Bevel broken edge with a microgrinder initially to 35&#176;, followed by a second beveling at 25&#176;. Ensure tip is sharp and smooth. Store finished beveled micropipette in a Petri dish on a small amount of clay.</li>
</ol>
3. Preparation of Zebrafish Larvae
<ol>
	<li>7 days prior to surgery, set up mating tanks of male and female zebrafish.</li>
	<li>Collect embryos the following morning, 3&#160;hr&#160;after the lights come on to ensure maximum yield. If using a transgenic reporter line such as Tg(elevl3:eGFP)knu3, sort fertilized embryos 100/100 mm plate in 25 ml of E3 at 28.5 &#176;C. If using wildtype, sort fertilized embryos 25/100 mm plate in 25 ml of E3 at 28.5 &#176;C.</li>
	<li>If using a reporter line, screen embryos for fluorescent expression at 48 hpf. Allow identified embryos to mature at a density of 25/100 mm plate in 25 ml of E3 at 28.5 &#176;C.</li>
	<li>When larvae are 5 dpf, prepare surgery plate by covering Sylgard with E2 + 10 mg/L Gentamycin Sulfate (GS) + Tricaine.
	<ol>
		<li>Prepare recovery dish by adding 25 ml E2 + GS to a 100 mm Petri dish.</li>
		<li>Prepare scalpel by taping together three swabs. This will form a triangular tool with three grooves.</li>
		<li>Mount a prepared micropipette on the swabs by taping it into one of the grooves.</li>
	</ol>
	</li>
	<li>If reusing micropipettes, flush until clear with E2 + GS using a 1ml syringe and a 27 G&#160;needle prior to mounting on swabs.</li>
</ol>
4. Surgery
<ol>
	<li>Anesthetize 1 plate of larvae at a time (25 fish) with Tricaine. Fish are sufficiently anesthetized when they no longer exhibit touch response. It is important that fish are completely anesthetized prior to surgery, otherwise they will twitch when the scalpel touches them. Surgery is performed under a dissection microscope.</li>
	<li>Transfer larvae to surgery plate.
	<ol>
		<li>Under maximum magnification, rotate one larva at a time so that it lies on its side with its back closest to the hand holding the scalpel.</li>
		<li>Position forceps so that they rest on the Sylgard, angled over the width of the larva.</li>
		<li>Bracing the glass scalpel against one of the arms of the forceps, cut into the dorsal lateral face of the larva at the level of the anal pore, being sure not to cut beyond the ventral edge of the notochord. Twist the scalpel to sever the spinal cord.</li>
		<li>Repeat with remaining larvae. 
		Note: if a larva bleeds, it will not recover from the surgery. Immediately remove the larva from the surgery plate and euthanize it via Tricaine overdose.</li>
	</ol>
	</li>
	<li>Once surgery on the batch of larvae is complete, transfer injured animals to the recovery plate. This is to support the clearing of anesthesia.
	<ol>
		<li>Caution: when collecting injured larvae for transfer, make sure they are collected head or tail first: do not stress the injury site by bending the larvae. 
		Note: All devices used for surgery can be reused, including the micropipettes.</li>
	</ol>
	</li>
</ol>
5. Recovery
<ol>
	<li>Transfer injured larvae from the recovery plate to 100 mm plates filled with 25 ml E2 + GS at a density of 25/plate. Allow to recover in a 28.5 &#176;C incubator.</li>
	<li>Check plates daily, removing sick and dead animals. Do not change the media until Coleps (freshwater protozoa) are visible in the media. When changing the media, do not transfer the fish to a new plate; instead, remove as much media as possible and flood the same plate with new media. Repeat as necessary to reduce Coleps population.</li>
	<li>Feed daily with a small amount of powdered fry food. 
	Note: Live food (e.g., paramecia or rotifers) cannot be fed to injured larvae until after they have recovered locomotion. Otherwise, the live food will colonize the injury site and kill the larvae.</li>
</ol>

<ol>
	<li>Houweling, D. A., B&#228;r, P. R., Gispen, W. H., Joosten, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+cord+injury:+bridging+the+lesion+and+the+role+of+neurotrophic+factors+in+repair.">Spinal cord injury: bridging the lesion and the role of neurotrophic factors in repair.</a> Progress in brain research. 117, 455-471 (1998).</li><li>Mikami, Y., 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=Implantation+of+dendritic+cells+in+injured+adult+spinal+cord+results+in+activation+of+endogenous+neural+stem/progenitor+cells+leading+to+de+novo+neurogenesis+and+functional+recovery.">Implantation of dendritic cells in injured adult spinal cord results in activation of endogenous neural stem/progenitor cells leading to de novo neurogenesis and functional recovery.</a> Journal of neuroscience research. 76 (4), 453-465 (2004).</li><li>Chernoff, E. A. G., Sato, K., Corn, A., Karcavich, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+cord+regeneration:+intrinsic+properties+and+emerging+mechanisms.">Spinal cord regeneration: intrinsic properties and emerging mechanisms.</a> Seminars in Cell &amp; Developmental Biology. 13 (5), 361-368 (2002).</li><li>Kuscha, V., Barreiro-Iglesias, A., Becker, C. G., Becker, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasticity+of+tyrosine+hydroxylase+and+serotonergic+systems+in+the+regenerating+spinal+cord+of+adult+zebrafish.">Plasticity of tyrosine hydroxylase and serotonergic systems in the regenerating spinal cord of adult zebrafish.</a> The Journal of comparative neurology. 520 (5), 933-951 (2012).</li><li>Becker, C. G., Lieberoth, B. C., Morellini, F., Feldner, J., Becker, T., Schachner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=L1.1+is+involved+in+spinal+cord+regeneration+in+adult+zebrafish.">L1.1 is involved in spinal cord regeneration in adult zebrafish.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 24 (36), 7837-7842 (2004).</li><li>Hui, S. P., Dutta, A., Ghosh, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+response+after+crush+injury+in+adult+zebrafish+spinal+cord.">Cellular response after crush injury in adult zebrafish spinal cord.</a> Developmental Dynamics: An Official Publication of the American Association of Anatomists. 239 (11), 2962-2979 (2010).</li><li>Goldshmit, Y., Sztal, T. E., Jusuf, P. R., Hall, T. E., Nguyen-Chi, M., Currie, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fgf-dependent+glial+cell+bridges+facilitate+spinal+cord+regeneration+in+zebrafish.">Fgf-dependent glial cell bridges facilitate spinal cord regeneration in zebrafish.</a> The Journal of neuroscience: the official journal of the Society for Neuroscience. 32 (22), 7477-7492 (2012).</li><li>Reimer, M. 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=Motor+neuron+regeneration+in+adult+zebrafish.">Motor neuron regeneration in adult zebrafish.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 28 (34), 8510-8516 (2008).</li><li>Hale, M. E., Ritter, D. A., Fetcho, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+confocal+study+of+spinal+interneurons+in+living+larval+zebrafish.">A confocal study of spinal interneurons in living larval zebrafish.</a> The Journal of comparative neurology. 437 (1), 1-16 (2001).</li><li>Bhatt, D. H., Otto, S. J., Depoister, B., Fetcho, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+AMP-induced+repair+of+zebrafish+spinal+circuits.">Cyclic AMP-induced repair of zebrafish spinal circuits.</a> Science. 305 (5681), 254-258 (2004).</li><li>McClenahan, P., Troup, M., Scott, E. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fin-tail+coordination+during+escape+and+predatory+behavior+in+larval+zebrafish.">Fin-tail coordination during escape and predatory behavior in larval zebrafish.</a> PloS one. 7 (2), (2012).</li><li>Kim, C. 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=Repressor+activity+of+Headless/Tcf3+is+essential+for+vertebrate+head+formation.">Repressor activity of Headless/Tcf3 is essential for vertebrate head formation.</a> Nature. 407 (6806), 913-916 (2000).</li></ol>

The authors have nothing to disclose.

When initially learning this technique, we recommend attempting no more than 50-100 transections in a single session. After mastering this technique, we are able to transect up to 300 embryos per&#160;hr; however, this level of throughput requires a few months of weekly practice. We also recommend practicing with a reporter line and verifying complete transection until the incidence of incomplete spinal cord transection is reduced to less than 1%.
Spinal cord transection in the adult zebrafish...

Major trauma to the human spinal cord often results in permanent paralysis and loss of sensation below the level of injury, due to the inability to regrow axons or reinitiate neurogenesis1,2. In contrast to mammals, however,&#160;anamniotes including salamanders and zebrafish (Danio rerio) show robust recovery even after complete spinal cord transection3,4.
The adult zebrafish is a well-established model for studying the recovery process following spinal cord injury5-7. Following complete spinal cord transection, reestablishment of sensory and locomotive function is observed in the adult zebrafish by 6&#160;weeks post-injury8. In order to examine the regenerative process in vivo, we turned to the transparent larval zebrafish9.
Here we present a method to transect the spinal cord of a 5 days post-fertilization (dpf) larval zebrafish using a beveled microinjection pipette as a scalpel, modified from Bhatt, et al.10 This method supports high throughput, low mortality, and reproducibility. With practice, 300 larvae/hr can be transected, and over 6&#160;months of transections, including over 3,600 animals, 98.75% &#177; 0.72% survived until 7 days post-injury (dpi). Our data shows rapid recovery of sensory and locomotion as well: at 1 dpi, all movement by the injured fish is driven by pectoral fin locomotion only. However, larvae begin to respond to tungsten needle touch caudal to transection by 2 dpi, reestablish C-bend movement by 3 dpi, and display predatory swimming by 5 dpi11. Using antibody staining against acetylated tubulin, we have confirmed that axons are absent from the injury site at 1 dpi, but have crossed the injury site by 5 dpi. We believe this protocol will provide a valuable technique for the study of axonal regrowth and neurogenesis in the spinal cord following injury.

<table border="0" cellpadding="0" cellspacing="0" style="width:733px;" width="733">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Name of Material/ Equipment</td>
			<td style="width:179px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">60mm petri dish</td>
			<td style="width:179px;">VWR</td>
			<td style="width:119px;">82050-544</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">100mm petri dish</td>
			<td style="width:179px;">VWR</td>
			<td style="width:119px;">89038-968</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Sylgard 184 Silicone Elastomer Kit</td>
			<td style="width:179px;">Fisher Scientific</td>
			<td style="width:119px;">NC9644388</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:269px;">borosilicate capillary tubing: OD 1.00mm ID 0.78mm</td>
			<td style="width:179px;">Warner Instruments Inc.</td>
			<td style="width:119px;">64-0778</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">forceps</td>
			<td style="width:179px;">Fine Scientific Tools Inc.</td>
			<td style="width:119px;">11252-30</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">disssection microscope</td>
			<td style="width:179px;">Nikon</td>
			<td style="width:119px;">SMZ6454</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">microgrinder</td>
			<td style="width:179px;">Narishige</td>
			<td style="width:119px;">EG-44</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Gentamycin Sulfate</td>
			<td style="width:179px;">Amresco Inc.</td>
			<td style="width:119px;">0304-5G</td>
			<td>dissolve in water 10mg/ml, store at -20&#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Tricaine</td>
			<td style="width:179px;">Acros Organics</td>
			<td align="right" style="width:119px;">118000100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">cotton tipped applicator, wood, 6-inch</td>
			<td style="width:179px;">Fisher Scientific</td>
			<td style="width:119px;">23-400-101</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">1ml syringe</td>
			<td style="width:179px;">BD</td>
			<td align="right" style="width:119px;">309625</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">27 ga. needle</td>
			<td style="width:179px;">BD</td>
			<td align="right" style="width:119px;">305109</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Fry food</td>
			<td style="width:179px;">Argent Labs</td>
			<td style="width:119px;">F-ARGE-PTL-CN</td>
			<td>store at -20&#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">micropipette puller</td>
			<td style="width:179px;">Sutter Instrument Co.</td>
			<td style="width:119px;">Model P-97</td>
			<td>Box Filament FB330B</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;"></td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">20x E2 (1L)</td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td>store at RT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">17.5g NaCl</td>
			<td style="width:179px;">Fisher Scientific</td>
			<td style="width:119px;">S671-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">0.75g KCl</td>
			<td style="width:179px;">Fisher Scientific</td>
			<td style="width:119px;">P217-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">2.90g CaCl2&#183;2H2O</td>
			<td style="width:179px;">Sigma&#160;&#160;&#160;</td>
			<td style="width:119px;">C7902-500G</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">4.90g MgSO4&#183;7H2O</td>
			<td style="width:179px;">Merck</td>
			<td style="width:119px;">MX0070-1</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">0.41g KH2PO4</td>
			<td style="width:179px;">Fisher Scientific</td>
			<td style="width:119px;">P285-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">0.12g Na2HPO4</td>
			<td style="width:179px;">Sigma&#160;&#160;&#160;</td>
			<td style="width:119px;">S0876-500G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;"></td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">500x NaCO3 (10ml)</td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td>make fresh, discard extra</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">0.35g NaCO3</td>
			<td style="width:179px;">Sigma</td>
			<td style="width:119px;">S5761</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;"></td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">1x E2 (1L)</td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td>store at RT</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">50ml 20x E2</td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:269px;">2ml fresh 500x NaCO3</td>
			<td style="width:179px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

spinal cord transection in the larval zebrafish

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability to reinitiate spinal neurogenesis. However, some anamniotes including the zebrafish Danio rerio exhibit both sensory and functional recovery even after complete transection of the spinal cord. The adult zebrafish is an established model organism for studying regeneration following spinal cord injury, with sensory and motor recovery by 6&#160;weeks post-injury. To take advantage of in vivo analysis of the regenerative process available in the transparent larval zebrafish as well as genetic tools not accessible in the adult, we use the larval zebrafish to study regeneration after spinal cord transection. Here we demonstrate a method for reproducibly and verifiably transecting the larval spinal cord. After transection, our data shows sensory recovery beginning at 2&#160;days post-injury (dpi), with the C-bend movement detectable by 3 dpi and resumption of free swimming by 5 dpi. Thus we propose the larval zebrafish as a companion tool to the adult zebrafish for the study of recovery after spinal cord injury.

To reduce severity of tissue damage surrounding the injury site, proper beveling of the micropipette is critical. Figure 1A shows a correctly beveled tip. Using a tip that is too wide (Figure 1B) tends to result in higher fatalities due to the increased likelihood of nicking the dorsal aorta, while a tip that is too narrow (Figure 1C) tends to glance off the skin rather than cutting tissue.
To practice this technique, it is advantageous to use...

Watch this Scientific Journal Video about Spinal Cord Transection in the Larval Zebrafish at JoVE.com

Spinal Cord Transection in the Larval Zebrafish

After spinal transection, adult zebrafish have functional recovery by six weeks post-injury. To take advantage of larval transparency and faster recovery, we present a method for transecting the larval spinal cord. After transection, we observe sensory recovery beginning at 2&#160;days post-injury, and C-bend movement by 3 days post-injury.

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability ...

spinal-cord-transection-in-the-larval-zebrafish

Research

JoVE Journal

Neuroscience

11.8K vistas.  University of Utah.  Después de la transección de la médula, el pez cebra adulto tenga la recuperación funcional a las seis semanas posteriores a la lesión. Para aprovechar las ventajas de la transparencia de las larvas y una recuperación más rápida, se presenta un método para seccionar la médula espinal de las larvas. Después de transección, se observa la recuperación sensorial a partir de los 2 días después de la lesión, y el movimiento C-doble por 3 días después de la le...

Video: Spinal Cord Transection in the Larval Zebrafish

Dissection and Culture of Commissural Neurons from Embryonic Spinal Cord

Commissural neurons have been widely used to investigate the mechanisms underlying axon guidance during embryonic spinal cord development. The cell bodies of these neurons are located in the dorsal spinal cord and their axons follow stereotyped trajectories during embryonic development. Commissural axons initially project ventrally towards the floorplate. After crossing the midline, these axons turn anteriorly and project towards the brain. Each of these steps is regulated by the action of several guidance cues. Cultures highly enriched in commissural neurons are ideally suited for many experiments addressing the mechanisms of axon pathfinding, including turning assays, immunochemistry and biochemistry. Here, we describe a method to dissect and culture commissural neurons from E13 rat dorsal spinal cord. First, the spinal cord is isolated and dorsal strips are dissected out. The dorsal tissue is then dissociated into a cell suspension by trypsinization and mechanical disruption. Neurons are plated onto poly-L-lysine-coated glass coverslips or tissue-culture dishes. After 30 hours in vitro, most neurons have extended an axon. The purity of the culture (Yam et al. 2009), typically over 90%, can be assessed by immunolabeling with the commissural neuron markers DCC, LH2 and TAG1 (Helms and Johnson, 1998). This neuronal preparation is a useful tool for in vitro studies of the cellular and molecular mechanisms of commissural axon growth and guidance during spinal cord development.

This video demonstrates a method to dissect and culture commissural neurons from E13 rat dorsal spinal cord. Dissociated commissural neurons are useful to study the cellular and molecular mechanisms of axon growth and guidance.

Commissural neurons have been widely used to investigate the mechanisms underlying axon guidance during embryonic spinal cord development. The cell bodies ...

Spinal Cord Electrophysiology II: Extracellular Suction Electrode Fabrication

Development of neural circuitries and locomotion can be studied using neonatal rodent spinal cord central pattern generator (CPG) behavior. We demonstrate a method to fabricate suction electrodes that are used to examine CPG activity, or fictive locomotion, in dissected rodent spinal cords. The rodent spinal cords are placed in artificial cerebrospinal fluid and the ventral roots are drawn into the suction electrode. The electrode is constructed by modifying a commercially available suction electrode. A heavier silver wire is used instead of the standard wire given by the commercially available electrode. The glass tip on the commercial electrode is replaced with a plastic tip for increased durability. We prepare hand drawn electrodes and electrodes made from specific sizes of tubing, allowing consistency and reproducibility. Data is collected using an amplifier and neurogram acquisition software. Recordings are performed on an air table within a Faraday cage to prevent mechanical and electrical interference, respectively.

A demonstration of the fabrication and use of an extracellular suction electrode used to measure electrophysiological recordings of neonatal rodent spinal cords in vitro

Development of neural circuitries and locomotion can be studied using neonatal rodent spinal cord central pattern generator (CPG) behavior. We demonstrate ...

Forebrain Electrophysiological Recording in Larval Zebrafish

Epilepsy affects nearly 3 million people in the United States and up to 50 million people worldwide. Defined as the occurrence of spontaneous unprovoked seizures, epilepsy can be acquired as a result of an insult to the brain or a genetic mutation. Efforts to model seizures in animals have primarily utilized acquired insults (convulsant drugs, stimulation or brain injury) and genetic manipulations (antisense knockdown, homologous recombination or transgenesis) in rodents. Zebrafish are a vertebrate model system1-3 that could provide a valuable alternative to rodent-based epilepsy research. Zebrafish are used extensively in the study of vertebrate genetics or development, exhibit a high degree of genetic similarity to mammals and express homologs for ~85% of known human single-gene epilepsy mutations. Because of their small size (4-6 mm in length), zebrafish larvae can be maintained in fluid volumes as low as 100 &mu;l during early development and arrayed in multi-well plates. Reagents can be added directly to the solution in which embryos develop, simplifying drug administration and enabling rapid in vivo screening of test compounds4. Synthetic oligonucleotides (morpholinos), mutagenesis, zinc finger nuclease and transgenic approaches can be used to rapidly generate gene knockdown or mutation in zebrafish5-7. These properties afford zebrafish studies an unprecedented statistical power analysis advantage over rodents in the study of neurological disorders such as epilepsy. Because the "gold standard" for epilepsy research is to monitor and analyze the abnormal electrical discharges that originate in a central brain structure (i.e., seizures), a method to efficiently record brain activity in larval zebrafish is described here. This method is an adaptation of conventional extracellular recording techniques and allows for stable long-term monitoring of brain activity in intact zebrafish larvae. Sample recordings are shown for acute seizures induced by bath application of convulsant drugs and spontaneous seizures recorded in a genetically modified fish.

A simple method to record extracellular field potentials in the larval zebrafish forebrain is described. The method provides a robust in vivo read-out of seizure-like activity. This technique can be used with genetically modified zebrafish larvae carrying epilepsy-related genes or seizures evoked by administration of convulsant drugs.

Epilepsy affects nearly 3 million people in the United States and up to 50 million people worldwide. Defined as the occurrence of spontaneous unprovoked ...

Dissection and Lateral Mounting of Zebrafish Embryos: Analysis of Spinal Cord Development

The zebrafish spinal cord is an effective investigative model for nervous system research for several reasons. First, genetic, transgenic and gene knockdown approaches can be utilized to examine the molecular mechanisms underlying nervous system development. Second, large clutches of developmentally synchronized embryos provide large experimental sample sizes. Third, the optical clarity of the zebrafish embryo permits researchers to visualize progenitor, glial, and neuronal populations. Although zebrafish embryos are transparent, specimen thickness can impede effective microscopic visualization. One reason for this is the tandem development of the spinal cord and overlying somite tissue. Another reason is the large yolk ball, which is still present during periods of early neurogenesis. In this article, we demonstrate microdissection and removal of the yolk in fixed embryos, which allows microscopic visualization while preserving surrounding somite tissue. We also demonstrate semipermanent mounting of zebrafish embryos. This permits observation of neurodevelopment in the dorso-ventral and anterior-posterior axes, as it preserves the three-dimensionality of the tissue.

Developmental processes such as proliferation, patterning, differentiation, and axon guidance can be readily modeled in the zebrafish spinal cord. In this article, we describe a mounting procedure for zebrafish embryos, which optimizes visualization of these events.

The zebrafish spinal cord is an effective investigative model for nervous system research for several reasons. First, genetic, transgenic and gene ...

Complete Spinal Cord Injury and Brain Dissection Protocol for Subsequent Wholemount In Situ Hybridization in Larval Sea Lamprey

After a complete spinal cord injury, sea lampreys at first are paralyzed below the level of transection. However, they recover locomotion after several weeks, and this is accompanied by short distance regeneration (a few mm) of propriospinal axons and spinal-projecting axons from the brainstem. Among the 36 large identifiable spinal-projecting neurons, some are good regenerators and others are bad regenerators. These neurons can most easily be identified in wholemount CNS preparations. In order to understand the neuron-intrinsic mechanisms that favor or inhibit axon regeneration after injury in the vertebrates CNS, we determine differences in gene expression between the good and bad regenerators, and how expression is influenced by spinal cord transection. This paper illustrates the techniques for housing larval and recently transformed adult sea lampreys in fresh water tanks, producing complete spinal cord transections under microscopic vision, and preparing brain and spinal cord wholemounts for in situ hybridization. Briefly, animals are kept at 16&#160;&#176;C and anesthetized in 1% Benzocaine in lamprey Ringer. The spinal cord is transected with iridectomy scissors via a dorsal approach and the animal is allowed to recover in fresh water tanks at 23 &#176;C. For in situ hybridization, animals are reanesthetized and the brain and cord removed via a dorsal approach.

Complete Spinal Cord Injury and Brain Dissection Protocol for Subsequent Wholemount In Situ Hybridization in Larval Sea Lamprey

Lampreys recover locomotion after a complete spinal cord injury. However, some spinal-projecting neurons are good regenerators and others are not. This paper illustrates the techniques for housing sea lamprey larvae (and recently transformed adults), producing complete spinal cord transections and preparing wholemount brains and spinal cords for in situ hybridization.

After a complete spinal cord injury, sea lampreys at first are paralyzed below the level of transection. However, they recover locomotion after several ...

Diffusion Imaging in the Rat Cervical Spinal Cord

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a diagnostic and prognostic tool in cases of disease or injury. Diffusion weighted imaging (DWI), is sensitive to the thermal motion of water molecules and allows for inferences of tissue microstructure. This report describes a protocol to acquire and analyze DWI of the rat cervical spinal cord on a small-bore animal system. It demonstrates an imaging setup for the live anesthetized animal and recommends a DWI acquisition protocol for high-quality imaging, which includes stabilization of the cord and control of respiratory motion. Measurements with diffusion weighting along different directions and magnitudes (b-values) are used. Finally, several mathematical models of the resulting signal are used to derive maps of the diffusion processes within the spinal cord tissue that provide insight into the normal cord and can be used to monitor injury or disease processes noninvasively.

The goal of this protocol is to obtain high-quality diffusion weighted magnetic resonance imaging (DWI) of the rat spinal cord for noninvasive characterization of tissue microstructure. This protocol describes optimizations of the MRI sequence, radiofrequency coil, and analysis methods to enable DWI images free from artifacts.

Magnetic resonance imaging (MRI) is the state of the art approach for assessing the status of the spinal cord noninvasively, and can be used as a ...

Two-photon Imaging of Cellular Dynamics in the Mouse Spinal Cord

Two-photon (2P) microscopy is utilized to reveal cellular dynamics and interactions deep within living, intact tissues. Here, we present a method for live-cell imaging in the murine spinal cord. This technique is uniquely suited to analyze neural precursor cell (NPC) dynamics following transplantation into spinal cords undergoing neuroinflammatory demyelinating disorders. NPCs migrate to sites of axonal damage, proliferate, differentiate into oligodendrocytes, and participate in direct remyelination. NPCs are thereby a promising therapeutic treatment to ameliorate chronic demyelinating diseases. Because transplanted NPCs migrate to the damaged areas on the ventral side of the spinal cord, traditional intravital 2P imaging is impossible, and only information on static interactions was previously available using histochemical staining approaches. Although this method was generated to image transplanted NPCs in the ventral spinal cord, it can be applied to numerous studies of transplanted and endogenous cells throughout the entire spinal cord. In this article, we demonstrate the preparation and imaging of a spinal cord with enhanced yellow fluorescent protein-expressing axons and enhanced green fluorescent protein-expressing transplanted NPCs.

A new ex vivo preparation for imaging the mouse spinal cord. This protocol allows for two-photon imaging of live cellular interactions throughout the spinal cord.

Two-photon (2P) microscopy is utilized to reveal cellular dynamics and interactions deep within living, intact tissues. Here, we present a method for ...

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing organisms, combined with the embryonic optical clarity, served as initial compelling attributes of this model. Over the past two decades, the success of this model has been further propelled by its amenability to large-scale mutagenesis screens and by the ease of transgenesis. More recently, gene-editing approaches have extended the power of the model.
For neurodevelopmental studies, the zebrafish embryo and larva provide a model to which multiple methods can be applied. Here, we focus on methods that allow the study of an essential property of neurons, electrical excitability. Our preparation for the electrophysiological study of zebrafish spinal neurons involves the use of veterinarian suture glue to secure the preparation to a recording chamber. Alternative methods for recording from zebrafish embryos and larvae involve the attachment of the preparation to the chamber using a fine tungsten pin1,2,3,4,5. A tungsten pin is most often used to mount the preparation in a lateral orientation, although it has been used to mount larvae dorsal-side up4. The suture glue has been used to mount embryos and larvae in both orientations. Using the glue, a minimal dissection can be performed, allowing access to spinal neurons without the use of an enzymatic treatment, thereby avoiding any resultant damage. However, for larvae, it is necessary to apply a brief enzyme treatment to remove the muscle tissue surrounding the spinal cord. The methods described here have been used to study the intrinsic electrical properties of motor neurons, interneurons, and sensory neurons at several developmental stages6,7,8,9.

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

This manuscript describes methods for electrophysiological recordings from spinal neurons of zebrafish embryos and larvae. The preparation maintains neurons in situ and often involves minimum dissection. These methods allow for the electrophysiological study of a variety of spinal neurons, from the initial electrical excitability acquisition through the early larval stages.

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing ...

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in adult mammalian animals remains elusive. In this study, we describe an experimental procedure for measuring calcium dynamics through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy. This method enables recordings and quantifications of neural activity in bilateral mouse brain regions one at a time in the same experiment for a prolonged period in vivo. Key aspects of this method, which can be completed within an hour, include minimally invasive surgery procedures for creating dual optical windows, and the use of 2P imaging. Although we only demonstrate the technique in the S1 area, the method can be applied to other regions of the living brain facilitating the elucidation of structural and functional complexities of brain neural networks.

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

We describe an experimental procedure for measuring neuronal activity through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy in vivo.

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in ...

Laminectomy and Spinal Cord Window Implantation in the Mouse

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated digital vaporizer is utilized to achieve a stable plane of anesthesia at a low-flow rate of isoflurane. A single vertebral spine is removed, and a commercially available cover-glass is overlaid on a thin agarose bed. A 3D-printed plastic backplate is then affixed to the adjacent vertebral spines using tissue adhesive and dental cement. A stabilization platform is used to reduce motion artifact from respiration and heartbeat. This rapid and clamp-free method is well-suited for acute multi-photon fluorescence microscopy. Representative data are included for an application of this technique to two-photon microscopy of the spinal cord vasculature in transgenic mice expressing eGFP:Claudin-5 &#8212; a tight junction protein.

This protocol describes implantation of a glass window onto the spinal cord of a mouse to facilitate visualization by intravital microscopy.

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated ...