Name: excitotoxic stimulation of brain microslices as an in vitro model of stroke
Uploaded: 2014-02-04T14:45:00
Description: Watch this Scientific Journal Video about Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke at JoVE.com

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
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	<li>Sacrifice twelve week old male rats by decapitation. Rats can either be sacrificed by stunning and decapita...

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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.

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