This work was supported by research funds from the National Health and Medical Research Council of Australia, the Hunter Medical Research Institute, and the University of Newcastle.&#160;

All procedures are performed with approval from the University of Newcastle Animal Care and Ethics Committee, as well as in accordance with the relevant guidelines and regulations, including the NSW Animal Research Act, the NSW Animal Research Regulation, and the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes.
1. Dissection of Brain Tissue
<ol>
	<li>Sacrifice twelve week old male rats by decapitation. Rats can either be sacrificed by stunning and decapitation, or can be first anesthetized with isoflurane (5% induction, 1.5-2% maintenance) in 70% N2 and 30% O2, and then decapitated.</li>
	<li>Remove the brain from the skull as rapidly as possible (ideally, this should be performed in less than 2 min).</li>
	<li>Remove the cortex by free-hand dissection. The dissection should be performed in the minimum time possible, with as little damage to the brain as possible so as to maintain the integrity of the slices.</li>
	<li>In order to remove any residual skin, fur, blood, etc., immerse the brain in a small amount (3-5 ml) of 37 &#176;C Krebs buffer (118 mM sodium chloride, 4.7 mM potassium chloride, 1.3 mM calcium chloride, 1.2 mM potassium dihydrogen phosphate, 1.2 mM magnesium sulfate, 25 mM sodium hydrogen carbonate, 11.7 mM glucose, 0.03 mM disodium ethylenediaminetetraacetic acid (EDTA), equilibrated with 95% oxygen/5% carbon dioxide (carbogen), pH 7.4).</li>
</ol>
2. Preparation of Microslices
<ol>
	<li>Place the brain on the stage of a McIlwain chopper on which two slices of filter paper have been placed and moistened with warm Krebs buffer. Keep the brain and filter paper moistened with warm Krebs buffer, but not so wet that there is free liquid on the surface of the paper that can cause the brain to slide around.</li>
	<li>Slice the brain into 250 &#181;m coronal sections. As nutrients, oxygen, and waste materials that are normally exchanged with the blood supply are exchanged with a fluid which surrounds the tissue in isolated neural tissue, the size of the slices should not be more than 400 &#181;m in thickness to allow adequate oxygenation and nutrient exchange to occur.</li>
	<li>Turn the McIlwain stage 90&#176;.</li>
	<li>Slice brains into 250 &#181;m sagittal slices. Herein, these brain sections (250 &#181;m&#160;x 250 &#181;m slices of variable length depending on the thickness of the tissue) are referred to as microslices.</li>
	<li>Place the microslices into a round bottom tube with 10-15 ml 37 &#176;C Krebs buffer (the amount of Krebs buffer used will depend on the amount of tissue).</li>
</ol>
3. Equilibration of Microslices
<ol>
	<li>Gently agitate until individual microslices are suspended, and then allow them to settle under gravity.</li>
	<li>Carefully remove the supernatant, which will be cloudy due to suspended cell debris, and add 10 ml fresh 37 &#176;C Krebs buffer to the tube.</li>
	<li>Repeat this washing procedure four times, which will result in the removal of the majority of debris.</li>
	<li>Following this, equilibrate the microslices at 37 &#176;C with gentle shaking/inversion, and change the Krebs buffer every 15 min for 1 hr in total.</li>
	<li>At this time, add 2 ml fresh 37 &#176;C Krebs buffer, and transfer 15-20 microslices (150 &#181;l of microslice suspension) to flat bottom polystyrene 5 ml tubes using an extra wide bore pipette tip with smoothed edges (which can be created by cutting ~2 mm from the end of a P1000 tip). Spread the microslices evenly over the base of the tube in a single layer, so that each microslice is not further than a few millimeters from the oxygenated atmosphere.</li>
</ol>
4. Excitotoxic Stimulation
<ol>
	<li>Incubate the microslices at 37 &#176;C, and continually pass carbogen over the surface of the 150 &#181;l microslice suspension, using a gas line that is positioned just above the surface of the microslice suspension (to avoid mechanical disruption).</li>
	<li>Treat microslices with either 150 &#181;l 5 mM glutamate + 100 &#181;M glycine in Krebs buffer (excitotoxic stimulus: final concentration 2.5 mM glutamate + 50 &#181;M glycine) or 150 &#181;l Krebs buffer alone (control nonstimulated). A variety of stimuli can be used at this step (including, but not limited to, AMPA, NMDA + glycine, KCl depolarization, and oxygen/glucose deprivation).</li>
	<li>Remove the incubation solution at various times post-stimulation (0, 30, 60, 90, 120, and 300 sec), and replace it with 300 &#181;l of ice-cold homogenization buffer (30 mM Tris, pH 7.4, 1 mM ethylene glycol tetraacetic acid, 4 mM EDTA, 100 &#181;M ammonium molybdate, 5 mM sodium pyrophosphate, 25 mM sodium fluoride, 1 mM sodium orthovanadate, 1 mM phenylmethanesulfonylfluoride, complete protease inhibitor cocktail).</li>
	<li>Homogenize microslices on ice, using a glass-Teflon Dounce Homogenizer (20 strokes; 700 rpm).</li>
	<li>Store homogenates at -80 &#176;C, and various signaling molecules, death molecules, etc. can be measured by western blot.</li>
</ol>

<ol>
	<li>Lo, E. H., Dalkara, T., Moskowitz, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms,+challenges+and+opportunities+in+stroke.">Mechanisms, challenges and opportunities in stroke.</a> Nat. Rev. Neurosci. 4, 399-415 (2003).</li><li>Wang, Y., Qin, Z. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+and+cellular+mechanisms+of+excitotoxic+neuronal+death.">Molecular and cellular mechanisms of excitotoxic neuronal death.</a> Apoptosis. 15, 1382-1402 (2010).</li><li>Vogt Weisenhorn, D. M., Roback, L. J., Kwon, J. H., Wainer, B. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coupling+of+cAMP/PKA+and+MAPK+signaling+in+neuronal+cells+is+dependent+on+developmental+stage.">Coupling of cAMP/PKA and MAPK signaling in neuronal cells is dependent on developmental stage.</a> Exp. Neurol. 169 (1), 44-55 (2001).</li><li>Kharlamov, E., Cagnoli, C. M., Atabay, C., Ikonomovic, S., Grayson, D. R., Manev, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Opposite+effect+of+protein+synthesis+inhibitors+on+potassium+deficiency-induced+apoptotic+cell+death+in+immature+and+mature+neuronal+cultures.">Opposite effect of protein synthesis inhibitors on potassium deficiency-induced apoptotic cell death in immature and mature neuronal cultures.</a> J. Neurochem. 65 (3), 1395-1398 (1995).</li><li>Kristensen, B. W., Noraberg, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+excitotoxic+profiles+of+ATPA,+AMPA,+KA+and+NMDA+in+organotypic+hippocampal+slice+cultures.">Comparison of excitotoxic profiles of ATPA, AMPA, KA and NMDA in organotypic hippocampal slice cultures.</a> Brain Res. 917 (1), 21-44 (2001).</li><li>Lecrux, C., 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=Spontaneously+hypertensive+rats+are+highly+vulnerable+to+AMPA-induced+brain+lesions.">Spontaneously hypertensive rats are highly vulnerable to AMPA-induced brain lesions.</a> Stroke. 38, 3007-3015 (2007).</li><li>Sattler, R., Charlton, M. P., Hafner, M., Tymianski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+influx+pathways,+not+calcium+load,+determine+neuronal+vulnerability+to+calcium+neurotoxicity.">Distinct influx pathways, not calcium load, determine neuronal vulnerability to calcium neurotoxicity.</a> J. Neurochem. 71, 2349-2364 (1998).</li><li>Morrison, B. 3. r. d., Saatman, K. E., Meaney, D. F., McIntosh, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+central+nervous+system+models+of+mechanically+induced+trauma:+a+review.">In vitro central nervous system models of mechanically induced trauma: a review.</a> J. Neurotrauma. 15, 911-928 (1998).</li><li>McIlwain, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+Neurochemistry.">Practical Neurochemistry.</a> , (1975).</li><li>Skelding, K. A., Spratt, N. J., Fluechter, L., Dickson, P. W., Rostas, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=alpha+CaMKII+is+differentially+regulated+in+brain+regions+that+exhibit+differing+sensitivities+to+ischemia+and+excitotoxicity.">alpha CaMKII is differentially regulated in brain regions that exhibit differing sensitivities to ischemia and excitotoxicity.</a> J. Cereb. Blood Flow Metab. 32 (12), 2181-2192 (2012).</li><li>Kavanagh, J. M., Dodd, P. R., Rostas, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3H]MK-801+binding+in+immature+and+mature+chicken+forebrain.">3H]MK-801 binding in immature and mature chicken forebrain.</a> Neurosci. Lett. 134 (1), 83-87 (1991).</li><li>Kavanagh, J. M., Bunn, S. J., Boyd, T. L., Rostas, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+changes+in+glutamate+receptor+stimulated+inositol+phospholipid+metabolism+and+45Ca(2+)-accumulation+in+posthatch+chicken+forebrain.">Developmental changes in glutamate receptor stimulated inositol phospholipid metabolism and 45Ca(2+)-accumulation in posthatch chicken forebrain.</a> Neurosci. Lett. 194 (3), 161-164 (1995).</li><li>Sharps, E. S., McCarl, 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+high+performance+liquid+chromatographic+method+to+measure+32P+incorporation+into+phosphorylated+metabolites+in+cultured+cells.">A high performance liquid chromatographic method to measure 32P incorporation into phosphorylated metabolites in cultured cells.</a> Anal. Biochem. 124, 421-424 (1982).</li><li>Bradbury, D. A., Simmons, T. D., Slater, K. J., Crouch, S. P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurment+of+the+ADP:ATP+ratio+in+human+leukaemic+cell+lines+can+be+used+as+an+indicator+of+cell+viability,+necrosis+and+apoptosis.">Measurment of the ADP:ATP ratio in human leukaemic cell lines can be used as an indicator of cell viability, necrosis and apoptosis.</a> J. Immunol. Methods. 240 (1-2), 1-2 (2000).</li><li>Rodnight, R., McIlwain, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Techniques+in+tissue+metabolism:+3.+Study+of+tissue+fragments+with+little+or+no+added+aqueous+phase,+and+in+oils.">Techniques in tissue metabolism: 3. Study of tissue fragments with little or no added aqueous phase, and in oils.</a> Biochem. J. 57, 649-661 (1954).</li><li>Shelanski, M. L., Gaskin, F., Cantor, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microtubule+assembly+in+the+absence+of+added+nucleotides.">Microtubule assembly in the absence of added nucleotides.</a> Proc. Natl. Acad. Sci. U.S.A. 70 (3), 765-768 (1973).</li></ol>

The authors declare that they have no conflict of interest regarding any of the work conducted within this manuscript.

Herein, an in vitro technique for the generation of microslices that can be used to examine the molecular mechanisms involved in excitotoxicity and ischemia-mediated cell death in intact mature brain tissue is described. This technique produces viable tissue (Figures 1-3), that is metabolically similar to larger organotypic slices15. Furthermore, this microslice model closely corresponds to the response observed following excitotoxicity mediated brain injuries in vivo10<...

The most common form of stroke is ischemic stroke, which occurs when a cerebral blood vessel becomes occluded. The tissue ischemia which results from cessation of blood flow causes widespread depolarization of membranes, release of excitatory neurotransmitters, and sustained elevation of intracellular calcium, which leads to the activation of cell death pathways 1. This process has been termed &#39;excitotoxicity&#39;, and is a common pathway involved in neuronal death produced by a variety of pathologies, including stroke 2. Inhibition of the signaling pathways involved in excitotoxicity and other neuronal cell death cascades is an appealing approach to limit neuronal damage following stroke.
Identifying the precise molecular mechanisms involved in excitotoxicity and ischemic stroke can be difficult when using whole animal systems. As such, primary embryonic and &#39;neuronal-like&#39; (e.g. neuroblastoma and adenocarcinoma immortalized lines) cell culture systems are often used. The main advantages of these models are that they are easy to manipulate, relatively cost-effective, and cell death can be readily measured and quantitated. However, signaling pathways can be altered by the culturing conditions used 3,4, and immature neurons and immortalized lines can express different receptors and signaling molecules when compared to mature brain 5-8. Furthermore, cultured neurons only allow the examination of one cell type (or two, if a coculture system is used), whereas intact brain tissue is heterogeneous, containing a variety of cell types that interact with each other. Organotypic slice culture systems (thin explants of brain tissue) are also used, and these models allow the study of heterogeneous populations of cells as they are found in vivo. However, only a limited amount of tissue can be obtained from each animal when using this technique, slices cannot be cultured for as long as immortalized cell lines, and medium to long-term culture can result in alterations in signaling pathways and receptors in the slices. Whilst mature brain can be used to generate organotypic slices, slices from immature brain are more amenable to culture, and are more commonly utilized. There is therefore the need to develop models which mimic or represent intact mature brain, that are easy to use, in which neuronal signaling pathways can be examined.
Herein, an in vitro technique involving intact nervous tissue that can be used to elucidate molecular mechanisms involved in cell death following an excitotoxic or ischemic insult is described. This technique reduces the number of animals required to perform an experiment, is reproducible, and generates viable tissue that behaves in a metabolically similar fashion to larger organotypic slices. Additionally, the neuronal circuitry, cellular interactions, and postsynaptic compartment remains partly intact. The physiological buffer used allows the cell membranes to &#39;reseal&#39;, and enables cells to recover their original membrane resistance 9. This brain slice model is able to faithfully mimic responses observed following excitotoxicity mediated brain injuries 10, and can be used to examine the molecular mechanisms involved in stroke.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Guillotine</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Used to decapitate animal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Surgical equipment</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>Forceps, scissors, tweezers, etc, for brain removal and dissection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">McIlwain chopper</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>Used to generate 100-400 &#956;m brain sections.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>McIlwain choppers are manufactured/distributed by a range of companies including Mickle Engineering, Harvard Apparatus, Campden Instruments and Ted Pella.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Round bottom plastic tubes</td>
			<td style="width:71px;">Greiner</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Water bath</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>For keeping tissue at 37 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Aerating apparatus</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td>Used to keep microslices in a humidified, oxygenated environment</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Flat bottomed polystyrene tubes</td>
			<td style="width:71px;">Nunc</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dounce Homogenizer</td>
			<td style="width:71px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

excitotoxic stimulation of brain microslices as an in vitro model of stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or &#39;neuronal-like&#39; cell culture systems are commonly utilized. While&#160;these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.

Microslices generated using this procedure are viable, and a variety of species (for example, rat, mouse, and chicken) can be used to produce microslices. Three independent measures of viability have been utilized: respiration rate (Figure 1), adenine nucleotide ratios (Figure 2), and tissue potassium content (Figure 3). Using these measures, it has been demonstrated that microslices remain viable for at least 2 hr post-generation.
Brain micro...

Watch this Scientific Journal Video about Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke at JoVE.com

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

We have developed a brain slice model which can be used to examine molecular mechanisms involved in excitotoxicity-mediated brain injury.&#160;This technique generates viable mature brain tissue and reduces animal numbers required for experimentation, whilst keeping the neuronal circuitry, cellular interactions, and postsynaptic compartments partly intact.

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As ...

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8.4K visualizações.  The University of Newcastle.  Nós desenvolvemos um modelo de fatia de cérebro que podem ser utilizados para examinar os mecanismos moleculares envolvidos na lesão cerebral mediada por excitotoxicidade. Esta técnica gera tecido cerebral maduro viável e reduz o número de animais necessários para a experimentação, mantendo o circuito neuronal, interações celulares e compartimentos pós-sinápticos em parte intacta. 

Vídeo: Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Bilateral Common Carotid Artery Occlusion as an Adequate Preconditioning Stimulus to Induce Early Ischemic Tolerance to Focal Cerebral Ischemia

There is accumulating evidence, that ischemic preconditioning - a non-damaging ischemic challenge to the brain - confers a transient protection to a subsequent damaging ischemic insult. We have established bilateral common carotid artery occlusion as a preconditioning stimulus to induce early ischemic tolerance to transient focal cerebral ischemia in C57Bl6/J mice. In this video, we will demonstrate the methodology used for this study.

There is accumulating evidence, that ischemic preconditioning (PC) &#x2013; a non-damaging ischemic challenge to the brain - confers a transient protection to a subsequent damaging ischemic insult. We established bilateral common carotid artery occlusion (BCCAO) as a preconditioning stimulus to induce early ischemic tolerance (IT) to transient focal cerebral ischemia (induced by middle cerebral artery occlusion, MCAO) in C57Bl6/J mice.

There is accumulating evidence, that ischemic preconditioning - a non-damaging ischemic challenge to the brain - confers a transient protection to a ...

A Murine Model of Subarachnoid Hemorrhage

In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice.

A standardized mouse model of subarachnoid hemorrhage by intraluminal Circle of Willis perforation is described. Vessel perforation and subarachnoid bleeding are monitored by intracranial pressure monitoring. In addition various vital parameters are recorded and controlled to maintain physiologic conditions.

In this video publication a standardized mouse model of subarachnoid  hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of  Willis ...

Stretch in Brain Microvascular Endothelial Cells (cEND) as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying mechanisms involved in it are useful for treatment. There are both in vivo and in vitro methods available for this purpose. In vivo models can mimic actual head injury as it occurs during TBI. However, in vivo techniques may not be exploited for studies at the cell physiology level. Hence, in vitro methods are more advantageous for this purpose since they provide easier access to the cells and the extracellular environment for manipulation.
Our protocol presents an in vitro model of TBI using stretch injury in brain microvascular endothelial cells. It utilizes pressure applied to the cells cultured in flexible-bottomed wells. The pressure applied may easily be controlled and can produce injury that ranges from low to severe. The murine brain microvascular endothelial cells (cEND) generated in our laboratory is a well-suited model for the blood brain barrier (BBB) thus providing an advantage to other systems that employ a similar technique. In addition, due to the simplicity of the method, experimental set-ups are easily duplicated. Thus, this model can be used in studying the cellular and molecular mechanisms involved in TBI at the BBB.

Stretch in Brain Microvascular Endothelial Cells cEND as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

In vitro traumatic brain injury models are being developed to reproduce in vivo brain deformation. Stretch-induced injury has been employed for astrocytes, neurons, glial cells, aortic, and brain endothelial cells. However, our system uses a blood brain barrier (BBB) model that possesses properties constituting a legitimate model of the BBB to establish an in vitro&#160;TBI model.

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying ...

Setting-up an In Vitro Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport

The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and characterize a highly reproducible rat syngeneic in vitro model of the BBB using co-cultures of primary rat brain endothelial cells (RBEC) and astrocytes to study receptors involved in transcytosis across the endothelial cell monolayer. Astrocytes were isolated by mechanical dissection following trypsin digestion and were frozen for later co-culture. RBEC were isolated from 5-week-old rat cortices. The brains were cleaned of meninges and white matter, and mechanically dissociated following enzymatic digestion. Thereafter, the tissue homogenate was centrifuged in bovine serum albumin to separate vessel fragments from nervous tissue. The vessel fragments underwent a second enzymatic digestion to free endothelial cells from their extracellular matrix. The remaining contaminating cells such as pericytes were further eliminated by plating the microvessel fragments in puromycin-containing medium. They were then passaged onto filters for co-culture with astrocytes grown on the bottom of the wells. RBEC expressed high levels of tight junction (TJ) proteins such as occludin, claudin-5 and ZO-1 with a typical localization at the cell borders. The transendothelial electrical resistance (TEER) of brain endothelial monolayers, indicating the tightness of TJs reached 300 ohm&#183;cm2 on average. The endothelial permeability coefficients (Pe) for lucifer yellow (LY) was highly reproducible with an average of 0.26 &#177;&#160;0.11 x 10-3 cm/min. Brain endothelial cells organized in monolayers expressed the efflux transporter P-glycoprotein (P-gp), showed a polarized transport of rhodamine 123, a ligand for P-gp, and showed specific transport of transferrin-Cy3 and DiILDL across the endothelial cell monolayer. In conclusion, we provide a protocol for setting up an in vitro BBB model that is highly reproducible due to the quality assurance methods, and that is suitable for research on BBB transporters and receptors.

Setting-up an In Vitro Model of Rat Blood-brain Barrier BBB: A Focus on BBB Impermeability and Receptor-mediated Transport

The aim of the present study was to validate the reproducibility of an in vitro BBB model involving a rat syngeneic co-culture of endothelial cells and astrocytes. The endothelial cell monolayer presented high TEER and low LY permeability. Expression of specific TJ proteins, functional responses to inflammation and functionality of transporters and receptors were assessed.

The blood brain barrier (BBB) specifically regulates molecular and cellular flux between the blood and the nervous tissue. Our aim was to develop and ...

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic cerebrovascular accidents account for 80% of all strokes. A common cause of IR injury is the rapid inflow of fluids following an acute/chronic occlusion of blood, nutrients, oxygen to the tissue triggering the formation of free radicals.
Ischemic stroke is followed by blood-brain barrier (BBB) dysfunction and vasogenic brain edema. Structurally, tight junctions (TJs) between the endothelial cells play an important role in maintaining the integrity of the blood-brain barrier (BBB). IR injury is an early secondary injury leading to a non-specific, inflammatory response. Oxidative and metabolic stress following inflammation triggers secondary brain damage including BBB permeability and disruption of tight junction (TJ) integrity.
Our protocol presents an in vitro example of oxygen-glucose deprivation and reoxygenation (OGD-R) on rat brain endothelial cell TJ integrity and stress fiber formation. Currently, several experimental in vivo models are used to study the effects of IR injury; however they have several limitations, such as the technical challenges in performing surgeries, gene dependent molecular influences and difficulty in studying mechanistic relationships. However, in vitro models may aid in overcoming many of those limitations. The presented protocol can be used to study the various molecular mechanisms and mechanistic relationships to provide potential therapeutic strategies. However, the results of in vitro studies may differ from standard in vivo studies and should be interpreted with caution.

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is associated with a high rate of morbidity and mortality. The goal of the in vitro model of oxygen-glucose deprivation and reoxygenation (OGD-R) described here is to assess the effects of ischemia reperfusion injury on a variety of cells, particularly in blood-brain barrier (BBB) endothelial cells.

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic ...

A Multimodal Imaging- and Stimulation-based Method of Evaluating Connectivity-related Brain Excitability in Patients with Epilepsy

Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations over time in the blood-oxygenation level dependent signal. rs-fcMRI has been applied extensively to identify abnormalities in brain connectivity in different neurologic and psychiatric diseases. However, the relationship among rs-fcMRI connectivity abnormalities, brain electrophysiology and disease state is unknown, in part because the causal significance of alterations in functional connectivity in disease pathophysiology has not been established. Transcranial Magnetic Stimulation (TMS) is a technique that uses electromagnetic induction to noninvasively produce focal changes in cortical activity. When combined with electroencephalography (EEG), TMS can be used to assess the brain's response to external perturbations. Here we provide a protocol for combining rs-fcMRI, TMS and EEG to assess the physiologic significance of alterations in functional connectivity in patients with neuropsychiatric disease. We provide representative results from a previously published study in which rs-fcMRI was used to identify regions with abnormal connectivity in patients with epilepsy due to a malformation of cortical development, periventricular nodular heterotopia (PNH). Stimulation in patients with epilepsy resulted in abnormal TMS-evoked EEG activity relative to stimulation of the same sites in matched healthy control patients, with an abnormal increase in the late component of the TMS-evoked potential, consistent with cortical hyperexcitability. This abnormality was specific to regions with abnormal resting-state functional connectivity. Electrical source analysis in a subject with previously recorded seizures demonstrated that the origin of the abnormal TMS-evoked activity co-localized with the seizure-onset zone, suggesting the presence of an epileptogenic circuit. These results demonstrate how rs-fcMRI, TMS and EEG can be utilized together to identify and understand the physiological significance of abnormal brain connectivity in human diseases.

Resting-state functional-connectivity MRI has identified abnormalities in patients with a wide range of neuropsychiatric disorders, including epilepsy due to malformations of cortical development. Transcranial Magnetic Stimulation in combination with EEG can demonstrate that patients with epilepsy have cortical hyperexcitability in regions with abnormal connectivity.

Resting-state functional connectivity MRI (rs-fcMRI) is a technique that identifies connectivity between different brain regions based on correlations ...

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

The goal of this protocol is to demonstrate the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The technique can be utilized as an in vitro screening tool in hearing research.

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a ...

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) models based on pBECs in mono-culture (MC), MC with astrocyte-conditioned medium (ACM), and non-contact co-culture (NCC) with astrocytes of porcine or rat origin. pBECs were isolated and cultured from fragments of capillaries from the brain cortices of domestic pigs 5-6 months old. These fragments were purified by careful removal of meninges, isolation and homogenization of grey matter, filtration, enzymatic digestion, and centrifugation. To further eliminate contaminating cells, the capillary fragments were cultured with puromycin-containing medium. When 60-95% confluent, pBECs growing from the capillary fragments were passaged to permeable membrane filter inserts and established in the models. To increase barrier tightness and BBB characteristic phenotype of pBECs, the cells were treated with the following differentiation factors: membrane permeant 8-CPT-cAMP (here abbreviated cAMP), hydrocortisone, and a phosphodiesterase inhibitor, RO-20-1724 (RO). The procedure was carried out over a period of 9-11 days, and when establishing the NCC model, the astrocytes were cultured 2-8 weeks in advance. Adherence to the described procedures in the protocol has allowed the establishment of endothelial layers with highly restricted paracellular permeability, with the NCC model showing an average transendothelial electrical resistance (TEER) of 1249 &#177; 80 &#937; cm2, and paracellular permeability (Papp) for Lucifer Yellow of 0.90 10-6 &#177; 0.13 10-6 cm sec-1 (mean &#177; SEM, n=55). Further evaluation of this pBEC phenotype showed good expression of the tight junctional proteins claudin 5, ZO-1, occludin and adherens junction protein p120 catenin. The model presented can be used for a range of studies of the BBB in health and disease and, with the highly restrictive paracellular permeability, this model is suitable for studies of transport and intracellular trafficking.

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of the protocol is to present an optimized procedure for the establishment of an in vitro blood-brain barrier (BBB) model based on primary porcine brain endothelial cells (pBECs). The model shows high reproducibility, high tightness, and is suitable for studies of transport and intracellular trafficking in drug discovery.

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) ...

Vagus Nerve Stimulation As an Adjunctive Neurostimulation Tool in Treatment-resistant Depression

Vagus nerve stimulation (VNS) is an approved neurostimulation therapy. The purpose of the method is to treat patients with therapy-resistant depression (TRD). VNS exhibits antidepressive and stabilizing effects. This method is particularly useful as a long-term treatment, in which up to two-thirds of patients respond. The vagus nerve stimulator is positioned on the left vagus nerve during a surgical procedure and is activated telemetrically by a wand connected to a handheld computerized device. The treating physician can perform various adjustments of the vagus nerve stimulator during in-office visits (e.g., by modifying stimulation intensity or stimulation frequency) to achieve maximum therapeutic effects with low side effects. Set-up of the device usually takes several months. Typical side effects include wound infection, temporary salivation, coughing, paralysis of the vocal cords, bradycardia, or even asystole. The patient can stop the VNS by placing a magnet over the generator. The current protocol describes delivery of the specific stimulation tool and methods for adjusting the tuning parameters to achieve the best remission rates in patients with TRD.

Vagus nerve stimulation (VNS) has been shown to be effective as an adjunct treatment for treatment-resistant depression (TRD). VNS leads to antidepressive and antisuicidal effects and quality of life improvements. This protocol offers a step-by-step guide to managing and adjusting a vagus nerve stimulator for efficient treatment of TRD.

Vagus nerve stimulation (VNS) is an approved neurostimulation therapy. The purpose of the method is to treat patients with therapy-resistant depression ...

Updated Technique for Reliable, Easy, and Tolerated Transcranial Electrical Stimulation Including Transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a noninvasive method of neuromodulation using low-intensity direct electrical currents. This method of brain stimulation presents several potential advantages compared to other techniques, as it is noninvasive, cost-effective, broadly deployable, and well-tolerated provided proper equipment and protocols are administered. Even though tDCS is apparently simple to perform, correct administration of the tDCS session, especially the electrode positioning and preparation, is vital for ensuring reproducibility and tolerability. The electrode positioning and preparation steps are traditionally also the most time consuming and error-prone. To address these challenges, modern tDCS techniques, using fixed-position headgear and pre-assembled sponge electrodes, reduce complexity and setup time while also ensuring that the electrodes are consistently placed as intended. These modern tDCS methods present advantages for research, clinic, and remote-supervised (at home) settings. This article provides a comprehensive step-by-step guide for administering a tDCS session using fixed-position headgear and pre-assembled sponge electrodes. This guide demonstrates tDCS using commonly applied montages intended for motor cortex and dorsolateral prefrontal cortex (DLPFC) stimulation. As described, selection of the head size and montage-specific headgear automates electrode positioning. Fully assembled pre-saturated snap-electrodes are simply affixed to the set position snap-connectors on the headgear. The modern tDCS method is shown to reduce setup time and reduce errors for both novice and expert operators. The methods outlined in this article can be adapted to different applications of tDCS as well as other forms of transcranial electrical stimulation (tES) such as transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS). However, since tES is application specific, as appropriate, any methods recipe is customized to accommodate subject, indication, environment, and outcome specific features.

When administering transcranial direct current stimulation (tDCS), reproducible electrode preparation and placement are vital for a tolerated and effective session. The purpose of this article is to demonstrate updated modern setup procedures for the administration of tDCS and related transcranial electrical stimulation techniques, such as transcranial alternating current stimulation (tACS).

Transcranial direct current stimulation (tDCS) is a noninvasive method of neuromodulation using low-intensity direct electrical currents. This method of ...