Name: experimental models to study the neuroprotection of acidic postconditioning against cerebral ischemia
Uploaded: 2017-07-31T12:30:00
Description: Watch this Scientific Journal Video about Experimental Models to Study the Neuroprotection of Acidic Postconditioning Against Cerebral Ischemia at JoVE.com

This work was funded by the National Natural Science Foundation of China (81573406, 81373393, 81273506, 81221003, 81473186 and 81402907), Zhejiang Provincial Natural Science Foundation (LR15H310001) and the Program for Zhejiang Leading Team of S&amp;T Innovation Team (2011R50014).

All experiments were approved by and conducted in accordance with the ethical guidelines of the Zhejiang University Animal Experimentation Committee and were in complete compliance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Efforts were made to minimize any pain or discomfort, and the minimum number of animals was used.
1. OGD of Corticostriatal Slices
<ol>
	<li>Solution preparation:
	<ol>
		<li>Prepare 1,000 mL r-ACSF (124 mmol/...

<ol>
	<li>Zhao, H., Sapolsky, R. M., Steinberg, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interrupting+reperfusion+as+a+stroke+therapy:+ischemic+postconditioning+reduces+infarct+size+after+focal+ischemia+in+rats.">Interrupting reperfusion as a stroke therapy: ischemic postconditioning reduces infarct size after focal ischemia in rats.</a> J Cereb Blood Flow Metab. 26 (9), 1114-1121 (2006).</li><li>Leconte, 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=Delayed+hypoxic+postconditioning+protects+against+cerebral+ischemia+in+the+mouse.">Delayed hypoxic postconditioning protects against cerebral ischemia in the mouse.</a> Stroke. 40 (10), 3349-3355 (2009).</li><li>Fan, Y. 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=Transient+lack+of+glucose+but+not+O2+is+involved+in+ischemic+postconditioning-induced+neuroprotection.">Transient lack of glucose but not O2 is involved in ischemic postconditioning-induced neuroprotection.</a> CNS Neurosci Ther. 19 (1), 30-37 (2013).</li><li>Hess, D. C., Hoda, M. N., Bhatia, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Remote+limb+perconditioning+[corrected]+and+postconditioning:+will+it+translate+into+a+promising+treatment+for+acute+stroke.">Remote limb perconditioning [corrected] and postconditioning: will it translate into a promising treatment for acute stroke.</a> Stroke. 44 (4), 1191-1197 (2013).</li><li>Ren, C., Yan, Z., Wei, D., Gao, X., Chen, X., Zhao, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Limb+remote+ischemic+postconditioning+protects+against+focal+ischemia+in+rats.">Limb remote ischemic postconditioning protects against focal ischemia in rats.</a> Brain Res. 1288, 88-94 (2009).</li><li>Sun, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+effect+of+delayed+remote+limb+ischemic+postconditioning:+role+of+mitochondrial+K(ATP)+channels+in+a+rat+model+of+focal+cerebral+ischemic+reperfusion+injury.">Protective effect of delayed remote limb ischemic postconditioning: role of mitochondrial K(ATP) channels in a rat model of focal cerebral ischemic reperfusion injury.</a> J Cereb Blood Flow Metab. 32 (5), 851-859 (2012).</li><li>Li, P., 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=Remote+limb+ischemic+postconditioning+protects+mouse+brain+against+cerebral+ischemia/reperfusion+injury+via+upregulating+expression+of+Nrf2,+HO-1+and+NQO-1+in+mice.">Remote limb ischemic postconditioning protects mouse brain against cerebral ischemia/reperfusion injury via upregulating expression of Nrf2, HO-1 and NQO-1 in mice.</a> Int J Neurosci. , 1-8 (2015).</li><li>Fan, Y. 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=A+novel+neuroprotective+strategy+for+ischemic+stroke:+transient+mild+acidosis+treatment+by+CO2+inhalation+at+reperfusion.">A novel neuroprotective strategy for ischemic stroke: transient mild acidosis treatment by CO2 inhalation at reperfusion.</a> J Cereb Blood Flow Metab. 34 (2), 275-283 (2014).</li><li>Shen, Z., 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=PARK2-dependent+mitophagy+induced+by+acidic+postconditioning+protects+against+focal+cerebral+ischemia+and+extends+the+reperfusion+window.">PARK2-dependent mitophagy induced by acidic postconditioning protects against focal cerebral ischemia and extends the reperfusion window.</a> Autophagy. , (2017).</li><li>Skolnik, J., Takacs, L., Szende, E. <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+oxygen+consumption+of+slices+from+kidney,+brain,+cortex+and+liver+in+hypoxia.">In vitro oxygen consumption of slices from kidney, brain, cortex and liver in hypoxia.</a> Nature. 209 (5020), 305 (1966).</li><li>Lynch, G., Schubert, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+in+vitro.+brain+slices+for+multidisciplinary+studies+of+synaptic+function.">The use of in vitro. brain slices for multidisciplinary studies of synaptic function.</a> Annu Rev Neurosci. 3, 1-22 (1980).</li><li>Zheng, S., Zuo, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isoflurane+preconditioning+reduces+purkinje+cell+death+in+an+in+vitro+model+of+rat+cerebellar+ischemia.">Isoflurane preconditioning reduces purkinje cell death in an in vitro model of rat cerebellar ischemia.</a> Neuroscience. 118 (1), 99-106 (2003).</li><li>Yin, B., Barrionuevo, G., Weber, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+real-time+monitoring+of+glutathione+redox+status+in+single+pyramidal+neurons+in+organotypic+hippocampal+slices+during+oxygen-glucose+deprivation+and+reperfusion.">Optimized real-time monitoring of glutathione redox status in single pyramidal neurons in organotypic hippocampal slices during oxygen-glucose deprivation and reperfusion.</a> ACS Chem Neurosci. 6 (11), 1838-1848 (2015).</li><li>Medvedeva, Y. V., Ji, S., Yin, H. Z., Weiss, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+vulnerability+of+CA1+vs+CA3+pyramidal+neurons+after+ischemia:+possible+relationship+to+sources+of+Zn2++accumulation+and+its+entry+into+and+prolonged+effects+on+mitochondria.">Differential vulnerability of CA1 vs CA3 pyramidal neurons after ischemia: possible relationship to sources of Zn2+ accumulation and its entry into and prolonged effects on mitochondria.</a> J Neurosci. , (2016).</li><li>Pignataro, G., 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=In+vivo+and+in+vitro+characterization+of+a+novel+neuroprotective+strategy+for+stroke:+ischemic+postconditioning.">In vivo and in vitro characterization of a novel neuroprotective strategy for stroke: ischemic postconditioning.</a> J Cereb Blood Flow Metab. 28 (2), 232-241 (2008).</li><li>Zhang, X., Ding, H. Z., Jiang, S., Zeng, Y. M., Tang, Q. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+vitro+study+of+the+neuroprotective+effect+of+propofol+on+hypoxic+hippocampal+slice.">An in vitro study of the neuroprotective effect of propofol on hypoxic hippocampal slice.</a> Brain Inj. 28 (13-14), 1758-1765 (2014).</li><li>Niu, 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=Chemical+profiling+with+HPLC-FTMS+of+exogenous+and+endogenous+chemicals+susceptible+to+the+administration+of+chotosan+in+an+animal+model+of+type+2+diabetes-induced+dementia.">Chemical profiling with HPLC-FTMS of exogenous and endogenous chemicals susceptible to the administration of chotosan in an animal model of type 2 diabetes-induced dementia.</a> J Pharm Biomed Anal. 104, 21-30 (2015).</li></ol>

Here we present two experimental models to study the neuroprotection of APC against cerebral ischemia. In brain slices, APC is achieved by incubating mice corticostriatal slices in acidic buffer bubbled with 20% CO2 after reperfusion onset, while in the MCAO model, APC is achieved by inhaling 20% CO2 to mice after reperfusion. Both models reflect the neuroprotection of APC against cerebral ischemia. The protection was comparable with that achieved by ischemic postconditioning but with a wider time w...

Stroke is one of the leading causes of mortality and disability worldwide. Great efforts have been made to find effective treatments for stroke in the last decades, however, the achievement is quite unsatisfactory. Postconditioning is a process manipulated by subtoxic stresses following an ischemic episode. Postconditioning, including ischemic, hypoxic, low-glucose and remote ischemic postconditioning, trigger endogenous adaptive mechanisms, and have been proven to be promising therapies against cerebral ischemia1,2,3,4. However, ischemic postconditioning may introduce additional injury. Limb remote ischemic postconditioning usually needs several cycles of 5 - 20 min occlusion and reperfusion on the ipsilateral or bilateral hind limbs5,6,7. Therefore, these postconditioning manipulations are dangerous or impractical in clinical practice. To overcome these disadvantages, we have developed APC as a therapy for focal cerebral ischemia in mice8. Induced simply by inhaling 20% CO2, APC significantly reduces ischemic brain injury in a more feasible and safer way. Recently we have proved that APC extends the reperfusion window, highlighting the significance of APC for stroke therapy9.
Here we present two experimental models to study the neuroprotection of APC against cerebral ischemia. The first one is the oxygen-glucose deprivation (OGD) model in mice corticostriatal slices. Rapid preparation and transfer of the brain slices into an artificial environment, usually artificial cerebrospinal fluid (ASCF), can maintain cell viability and neuronal circuitry, which makes it possible to study brain function in vitro10,11. OGD in ASCF mimics cerebral ischemia and induces ischemic injury12,13,14. After OGD, the brain slices are refreshed in regular ASCF (r-ASCF) to provide reperfusion and then treated with APC using acidic ASCF bubbled with 20% CO2. The corticostriatal slice maintains the intact histological characterization compared with primary cultured cells.
To study brain function in vivo, the mouse middle cerebral artery occlusion (MCAO) model is employed. The middle cerebral artery is blocked by inserting a flame-blunted monofilament via the common carotid artery. As one of the most widely used stroke models, the MCAO model shows clinical relevance and the application of a monofilament makes it easier to achieve reperfusion. Simply by inhaling normoxic mixed gas containing 20% CO2 after the onset of reperfusion, APC showed significant protective effects against cerebral ischemia indicated by reduced brain infarct volumes.

<table border="0" cellpadding="0" cellspacing="0" width="723">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium chloride</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">S5886</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Potassium chloride</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">P5405</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Potassium phosphate monobasic</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">P9791</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Magnesium sulfate</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">M2643</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sodium bicarbonate</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">S5761</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Calcium chloride dihydrate</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">C5080</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">D-(+)-Glucose</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">G7021</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Vibratome</td>
			<td style="width:183px;">Leica</td>
			<td style="width:157px;">VT1000 S</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">2,3,5-triphenyltetrazolium hydrochloride</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">T8877</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Absolute Ethanol</td>
			<td style="width:183px;">Aladdin Industrial Corporation</td>
			<td style="width:157px;">E111993</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Dimethyl sulfoxide</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:157px;">D8418</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Laser Doppler Flowmetry</td>
			<td style="width:183px;">Moor Instruments Ltd</td>
			<td style="width:157px;">Model Moor VMS-LDF2</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Diethyl ether anhydrous</td>
			<td style="width:183px;">Sinopharm Chemical Reagent Corporation</td>
			<td style="width:157px;">80059618</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Trichloroacetaldehycle hydrate</td>
			<td style="width:183px;">Sinopharm Chemical Reagent Corporation</td>
			<td style="width:157px;">30037517</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">10% Formalin</td>
			<td style="width:183px;">Aladdin Industrial Corporation</td>
			<td style="width:157px;">F111936</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">24-well plates</td>
			<td style="width:183px;">Jet Biofil</td>
			<td style="width:157px;">TCP-010-024</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

experimental models to study the neuroprotection of acidic postconditioning against cerebral ischemia

Stroke is one of the leading causes of mortality and disability worldwide, with limited therapeutic approaches. As an endogenous strategy for neuroprotection, postconditioning treatments have proven to be promising therapies against cerebral ischemia. However, complicated procedures and potential safety issues limit their clinical application. To overcome these disadvantages, we have developed acidic postconditioning (APC) as a therapy for experimental focal cerebral ischemia. APC refers to the mild acidosis treatment by inhaling CO2 during reperfusion following ischemia. Here we present two models to execute APC in vitro and in vivo, respectively. The oxygen-glucose deprivation (OGD) treatment of mice and the corticostriatal occlusion and middle cerebral artery occlusion (MCAO) of mice were employed to mimic cerebral ischemia. APC can be simply achieved by transferring brain slices to acidic buffer bubbled with 20% CO2, or by mice inhaling 20% CO2. APC showed significant protective effects against cerebral ischemia, as reflected by tissue viability and brain infarct volume.

In the corticostriatal slice model described above, corticostriatal slice viability was quantified by TTC assay at 1 h after reperfusion. TTC conversion was calculated by normalizing the absorption at 490 nm to the control slice. According to TTC conversion, APC protected against OGD-induced reperfusion injury in an onset time and duration-dependent manner. In detail, both 1 and 3 min of acidosis treatment significantly improved viability at 5 min after 15 min OGD, whereas 5 min did not (...

Watch this Scientific Journal Video about Experimental Models to Study the Neuroprotection of Acidic Postconditioning Against Cerebral Ischemia at JoVE.com

Experimental Models to Study the Neuroprotection of Acidic Postconditioning Against Cerebral Ischemia

Acidic postconditioning protects against cerebral ischemia. Here we present two models to execute APC. They are achieved respectively by transferring corticostriatal slices to acidic buffer after oxygen-glucose deprivation in vitro and by inhaling 20% CO2 after middle cerebral artery occlusion in vivo.

Stroke is one of the leading causes of mortality and disability worldwide, with limited therapeutic approaches. As an endogenous strategy for ...

The overall goal of acidosis treatment in a cortico striatal slice model in a middle cerebral artery occlusion model is to study the neuroprotective effect of acidic postconditioning against cerebral ischemia. This method can help answer key questions of how acidosis postconditioning may protect ischemic brain injury, and to develop new strategy for stroke therapy. The main advantage of this technique is being able to use widely available experiment models to study the neuroprotection of acidosis postconditioning.Demonstrating the procedure will be Yarong Zheng a graduate student from my lab. Begin by removing the brain from the skull of a decapitated mouse with a thin spatula and dropping it carefully into a beaker containing ice cold regular ACSF equilibrated with five percent carbon dioxide and 95%oxygen. Apply cryoprecipitate glue to the vibratone plate in two strips.Put a piece of three percent agarose on the glue strip furthest from the blade to support the brain. Then use forceps to transfer the brain to filter paper. Cut off the frontal pole and the cerebellum with a blade.Place the brain tissue vertically on the free strip of glue with the brain leaning against the agarose. Add ice cold ACSF to the cutting reservoir to submerge the brain and add ice to the ice holder area. Keep the ACSF in the reservoir bubbled with five percent carbon dioxide and 95%oxygen.After setting the vibratone to cut 400 micron sections, and correctly positioning the brain relative to the cutting blade, press the start-stop button to start automatic cutting. Use a Pasteur pipette with a cut tip to transfer five brain slices one by one and place them into the tissue holder in ice cold regular ACSF bubbled with five percent carbon dioxide and 95%oxygen. After 30 minutes at room temperature place the brain slices in a water bath at 37 degrees Celsius for ten minutes to recover synaptic function.Place glucose free ACSF and acidic ACSF into the 37 degree Celsius water bath and bubble the solutions with five percent carbon dioxide and 95%nitrogen and 20 percent carbon dioxide and 80%oxygen respectively for 30 minutes. Carefully transfer four of the five brain slices into a preheated 37 degree Celsius, glucose free ACSF and incubate for 15 minutes. To study the time window for acidic preconditioning transfer one slice directly from glucose free ACSF to acidic ACSF and transfer the other three slices to regular ACSF for reperfusion.After three minutes transfer the slice in acidic ACSF to regular ACSF. Then after five minutes in regular ACSF transfer one of the slices from regular ACSF to the tissue holder in acidic ACSF for three minutes. Transfer another slice in the same manner 15 minutes after reperfusion.The remaining slice that was placed in glucose free ACSF but not acidic ACSF is set as the oxygen glucose deprivation group. Transfer the slices from the ACSF into the wells of a 24 well plate containing TTC solution. Stretch out the slice in the solution.And then incubate at 37 degrees Celsius in a shallow water bath for 30 minutes. Next transfer the slices into clean, weighed, 1.5 milliliter centrifuge tubes covered in foil and measure the dry weight of the slices. After weighing, extract Formazan by adding a one to one solution of ethanol and dimethyl sulphoxide to the tubes at a volume to weight ratio of 10 to one.Incubate away from light for 24 hours. The next day transfer the ethanol dimethyl sulphoxide solution from the tubes to a 96 well plate and measure the absorbance at 490 nanometers using a plate reader. First confirm proper anesthesia by the absence of a toe pinch reflex.Then place the anesthetized mouse with LDF probe attached to its skull in a supine position and fix using sterile cotton threads. Disinfect the shaved skin of the neck with 75%ethyl alcohol. Then after making a peri median skin incision in the neck blunt dissect the soft tissues with forceps to expose the blood vessels.Add one drop of saline to the exposed tissues to keep them hydrated. Next, use ophthalmic forceps to dissect the common carotid artery from surrounding tissue and the vagus nerve. Be careful not to damage the vagus nerve.Place a micro vessel clamp at the distal end of the common carotid artery. And tie a dead knot with 6-0 silk sutures at the proximal end. Then tie a loose knot proximal to the clamp as a temporary suture.Next, use micro ophthalmic scissors to make a small longitudinal incision between the two knots as close to the dead knot as possible. Now insert a 12 millimeter, tip blunted monofilament through the incision into the artery lumen and advance it a few millimeters. Tighten the loose knot around the tip of the monofilament and then remove the clamp.Then use ophthalmic forceps to advance the filament into the internal carotid artery until the LDF software shows a sharp decline in blood flow. Record the start time of occlusion. Then cut off the LDF probe, and put the mouse in a 30 degree Celsius incubator for the one hour duration of occlusion.55 minutes after the start of occlusion reanesthetize the animal with isoflurane and position the animal as before. Then open the neck incision, and reexpose the common carotid artery. After the occlusion period, use ophthalmic forceps to gently pull out the filament to achieve reperfusion.Then turn the temporary suture into a permanent one by tightening the knot. For acidosis treatment change the gas inhaled by the nose cone to 20%carbon dioxide 20%oxygen, and 60%nitrogen for five minutes. After closing the incision with an interrupted surgical suture place the mouse in a 30 degree Celsius heated cage until the mouse regains consciousness.This histogram shows the results from the TTC assay performed on cortical slices after oxygen glucose deprivation and acidic postconditioning as demonstrated in this video. Three minutes of acidosis treatment was neuroprotective if treatment was initiated immediately or five minutes after oxygen glucose deprivation, but not if the slices were reperfused for 15 minutes. Mice were subjected to 60 minutes of middle cerebral artery occlusion and treated by inhaling 20%carbon dioxide for five minutes at five, 50, or 100 minutes after reperfusion.Infarct volume was quantified by two, three, five triphenyltetrazolium hydrochloride staining 24 hours after reperfusion as indicated by the black dotted lines. This histogram shows the percent infarct volume for each condition. The neuroprotection from acidic postconditioning was robust even when the onset time was delayed to 50 minutes after reperfusion.However, acidosis treatment initiated at 100 minutes did not block the ischemic injury. After watching the video you should have a good understanding of how to study the neuroprotection of acidosis postconditioning on OGD model of brain slices, and on MSO model of mice. While attempting the procedures it is important to remember that the extension and the duration of acidosis is very important to reproduce the protective effects.

experimental-models-to-study-neuroprotection-acidic-postconditioning

Research

JoVE Journal

Neuroscience

An Experimental Platform to Study the Closed-loop Performance of Brain-machine Interfaces

The non-stationary nature and variability of neuronal signals is a fundamental problem in brain-machine interfacing. We developed a brain-machine interface to assess the robustness of different control-laws applied to a closed-loop image stabilization task. Taking advantage of the well-characterized fly visuomotor pathway we record the electrical activity from an identified, motion-sensitive neuron, H1, to control the yaw rotation of a two-wheeled robot. The robot is equipped with 2 high-speed video cameras providing visual motion input to a fly placed in front of 2 CRT computer monitors. The activity of the H1 neuron indicates the direction and relative speed of the robot's rotation. The neural activity is filtered and fed back into the steering system of the robot by means of proportional and proportional/adaptive control. Our goal is to test and optimize the performance of various control laws under closed-loop conditions for a broader application also in other brain machine interfaces.

We use a closed-loop fly-machine interface to investigate general principles in neuronal control.

The non-stationary nature and variability of neuronal signals is a fundamental problem in brain-machine interfacing. We developed a brain-machine ...

Cerebral Blood Oxygenation Measurement Based on Oxygen-dependent Quenching of Phosphorescence

Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the 
neuro-metabolic-vascular relationship. Development of new pO2 measurement modalities with simultaneous monitoring of pO2 in larger fields of view with higher 
spatial and/or temporal resolution will enable greater insight into the functioning of the normal brain and will also have significant impact on diagnosis 
and treatment of neurovascular diseases such as stroke, Alzheimer's disease, and head injury.
Optical imaging modalities have shown a great potential to provide high spatiotemporal resolution and quantitative imaging of pO2 based on hemoglobin absorption in visible and near infrared range of optical spectrum. However, multispectral measurement of cerebral blood oxygenation relies on photon migration through the highly scattering brain tissue. Estimation and modeling of tissue optical parameters, which may undergo dynamic changes during the experiment, is typically required for accurate estimation of blood oxygenation. On the other hand, estimation of the partial pressure of oxygen (pO2) based on oxygen-dependent quenching of phosphorescence should not be significantly affected by the changes in the optical parameters of the tissue and provides an absolute measure of pO2. Experimental systems that utilize oxygen-sensitive dyes have been demonstrated in in vivo studies of the perfused tissue as well as for monitoring the oxygen content in tissue cultures, showing that phosphorescence quenching is a potent technology capable of accurate oxygen imaging in the physiological pO2 range. 
Here we demonstrate with two different imaging modalities how to perform measurement of pO2 in cortical vasculature based on phosphorescence lifetime imaging. In first demonstration we present wide field of view imaging of pO2 at the cortical surface of a rat. This imaging modality has relatively simple experimental setup based on a CCD camera and a pulsed green laser. An example of monitoring the cortical spreading depression based on phosphorescence lifetime of Oxyphor R3 dye was presented. In second demonstration we present a high resolution two-photon pO2 imaging in cortical micro vasculature of a mouse. The experimental setup includes a custom built 2-photon microscope with femtosecond laser, electro-optic modulator, and photon-counting photo multiplier tube. We present an example of imaging the pO2 heterogeneity in the cortical microvasculature including capillaries, using a novel PtP-C343 dye with enhanced 2-photon excitation cross section.
Click here to view the related article <a href="http://www.jove.com/Details.php?ID=1731">Synthesis and Calibration of Phosphorescent Nanoprobes for Oxygen Imaging in Biological Systems.</a>

We present an experimental procedure for measuring the partial pressure of oxygen (pO2) in cerebral vasculature based on oxygen-dependent quenching of phosphorescence. Animal preparation and imaging procedures were outlined for both large field of view CCD-based imaging of pO2 in rats and 2-photon excitation based imaging of pO2 in mice.

Monitoring of the spatiotemporal characteristics of cerebral blood and tissue oxygenation is crucial for better understanding of the 
...

Focal Cerebral Ischemia Model by Endovascular Suture Occlusion of the Middle Cerebral Artery in the Rat

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable clinical state; in the development of animal models of focal ischemia, however, achieving reproducibility of experimentally induced infarct volume is essential. The rat is a widely used animal model for stroke due to its relatively low animal husbandry costs and to the similarity of its cranial circulation to that of humans2,3. In humans, the middle cerebral artery (MCA) is most commonly affected in stroke syndromes and multiple methods of MCA occlusion (MCAO) have been described to mimic this clinical syndrome in animal models. Because recanalization commonly occurs following an acute stroke in the human, reperfusion after a period of occlusion has been included in many of these models. In this video, we demonstrate the transient endovascular suture MCAO model in the spontaneously hypertensive rat (SHR). A filament with a silicon tip coating is placed intraluminally at the MCA origin for 60 minutes, followed by reperfusion. Note that the optimal occlusion period may vary in other rat strains, such as Wistar or Sprague-Dawley. Several behavioral indicators of stroke in the rat are shown. Focal ischemia is confirmed using T2-weighted magnetic resonance images and by staining brain sections with 2,3,5-triphenyltetrazolium chloride (TTC) 24 hours after MCAO.

Surgical induction of ischemic brain damage in the rat is a widely used model for stroke research. Here we demonstrate the induction of focal cerebral ischemia by occlusion of the middle cerebral artery. Visualization of the resulting infarct by histological staining and magnetic resonance imaging is also shown.

Stroke is the leading cause of disability and the third leading cause of death in adults worldwide1. In human stroke, there exists a highly variable ...

Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology

We have developed a cell culture procedure that can produce large quantities of confluent monolayers of primary human fetal retinal pigment epithelium (hfRPE) cultures with morphological, physiological and genetic characteristics of native human RPE. These hfRPE cell cultures exhibit heavy pigmentation, and electron microscopy show extensive apical membrane microvilli. The junctional complexes were identified with immunofluorescence labeling of various tight junction proteins. Epithelial polarity and function of these easily reproducible primary cultures closely resemble previously studied mammalian models of native RPE, including human. These results were extended by the development of therapeutic interventions in several animal models of human eye disease. We have focused on strategies for the removal of abnormal fluid accumulation in the retina or subretinal space. The extracellular subretinal space separates the photoreceptor outer segments and the apical membrane of the RPE and is critical for maintenance of retinal attachments and a whole host of RPE/retina interactions.

We provide a reproducible method for culturing confluent monolayers of human fetal retinal pigment epithelial cells (hfRPE) cells that exhibit morphology, physiology, polarity, and protein and gene expression patterns of adult native tissue. This work has been extended to an animal model of several eye diseases.

We have developed a cell culture procedure that can produce large quantities of confluent monolayers of primary human fetal retinal pigment epithelium ...

Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound (fTCD)

There are many unanswered questions about cerebral lateralization. In particular, it remains unclear which aspects of language and nonverbal ability are lateralized, whether there are any disadvantages associated with atypical patterns of cerebral lateralization, and whether cerebral lateralization develops with age. In the past, researchers interested in these questions tended to use handedness as a proxy measure for cerebral lateralization, but this is unsatisfactory because handedness is only a weak and indirect indicator of laterality of cognitive functions1. Other methods, such as fMRI, are expensive for large-scale studies, and not always feasible with children2.
Here we will describe the use of functional transcranial Doppler ultrasound (fTCD) as a cost-effective, non-invasive and reliable method for assessing cerebral lateralization. The procedure involves measuring blood flow in the middle cerebral artery via an ultrasound probe placed just in front of the ear. Our work builds on work by Rune Aaslid, who co-introduced TCD in 1982, and Stefan Knecht, Michael Deppe and their colleagues at the University of M&uuml;nster, who pioneered the use of simultaneous measurements of left- and right middle cerebral artery blood flow, and devised a method of correcting for heart beat activity. This made it possible to see a clear increase in left-sided blood flow during language generation, with lateralization agreeing well with that obtained using other methods3.
The middle cerebral artery has a very wide vascular territory (see Figure 1) and the method does not provide useful information about localization within a hemisphere. Our experience suggests it is particularly sensitive to tasks that involve explicit or implicit speech production. The 'gold standard' task is a word generation task (e.g. think of as many words as you can that begin with the letter 'B') 4, but this is not suitable for young children and others with limited literacy skills. Compared with other brain imaging methods, fTCD is relatively unaffected by movement artefacts from speaking, and so we are able to get a reliable result from tasks that involve describing pictures aloud5,6. Accordingly, we have developed a child-friendly task that involves looking at video-clips that tell a story, and then describing what was seen.

Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound fTCD

Functional transcranial Doppler sonography (fTCD) is a simple and non-invasive ultrasound technique which can be used to assess the lateralization of cognitive functions, especially language, and is suitable for use with children.

There are many unanswered questions about cerebral lateralization.  In particular, it remains unclear which aspects of language and nonverbal ability are ...

Strategies for Study of Neuroprotection from Cold-preconditioning

Neurological injury is a frequent cause of morbidity and mortality from general anesthesia and related surgical procedures that could be alleviated by development of effective, easy to administer and safe preconditioning treatments. We seek to define the neural immune signaling responsible for cold-preconditioning as means to identify novel targets for therapeutics development to protect brain before injury onset. Low-level pro-inflammatory mediator signaling changes over time are essential for cold-preconditioning neuroprotection. This signaling is consistent with the basic tenets of physiological conditioning hormesis, which require that irritative stimuli reach a threshold magnitude with sufficient time for adaptation to the stimuli for protection to become evident.
Accordingly, delineation of the immune signaling involved in cold-preconditioning neuroprotection requires that biological systems and experimental manipulations plus technical capacities are highly reproducible and sensitive. Our approach is to use hippocampal slice cultures as an in vitro model that closely reflects their in vivo counterparts with multi-synaptic neural networks influenced by mature and quiescent macroglia / microglia. This glial state is particularly important for microglia since they are the principal source of cytokines, which are operative in the femtomolar range. Also, slice cultures can be maintained in vitro for several weeks, which is sufficient time to evoke activating stimuli and assess adaptive responses. Finally, environmental conditions can be accurately controlled using slice cultures so that cytokine signaling of cold-preconditioning can be measured, mimicked, and modulated to dissect the critical node aspects. Cytokine signaling system analyses require the use of sensitive and reproducible multiplexed techniques. We use quantitative PCR for TNF-&alpha; to screen for microglial activation followed by quantitative real-time qPCR array screening to assess tissue-wide cytokine changes. The latter is a most sensitive and reproducible means to measure multiple cytokine system signaling changes simultaneously. Significant changes are confirmed with targeted qPCR and then protein detection. We probe for tissue-based cytokine protein changes using multiplexed microsphere flow cytometric assays using Luminex technology. Cell-specific cytokine production is determined with double-label immunohistochemistry. Taken together, this brain tissue preparation and style of use, coupled to the suggested investigative strategies, may be an optimal approach for identifying potential targets for the development of novel therapeutics that could mimic the advantages of cold-preconditioning.

We seek to define the neural immune signaling responsible for cold-preconditioning as means to identify novel targets for therapeutics development to protect brain before injury onset. We present strategies for such work that require biological systems, experimental manipulations plus technical capacities that are highly reproducible and sensitive.

Neurological injury is a frequent cause of morbidity and mortality from general anesthesia and related surgical procedures that could be alleviated by ...

Genetic Manipulation of Cerebellar Granule Neurons In Vitro and In Vivo to Study Neuronal Morphology and Migration

Developmental events in the brain including neuronal morphogenesis and migration are highly orchestrated processes. In vitro and in vivo analyses allow for an in-depth characterization to identify pathways involved in these events. Cerebellar granule neurons (CGNs) that are derived from the developing cerebellum are an ideal model system that allows for morphological analyses. Here, we describe a method of how to genetically manipulate CGNs and how to study axono- and dendritogenesis of individual neurons. With this method the effects of RNA interference, overexpression or small molecules can be compared to control neurons. In addition, the rodent cerebellar cortex is an easily accessible in vivo system owing to its predominant postnatal development. We also present an in vivo electroporation technique to genetically manipulate the developing cerebella and describe subsequent cerebellar analyses to assess neuronal morphology and migration.

Genetic Manipulation of Cerebellar Granule Neurons In Vitro and In Vivo to Study Neuronal Morphology and Migration

Neuronal morphogenesis and migration are crucial events underlying proper brain development. Here, we describe methods to genetically manipulate cultured cerebellar granule neurons and the developing cerebellum for the assessment of morphology and migratory characteristics of neurons.

Developmental events in the brain including neuronal morphogenesis and migration are highly orchestrated processes. In vitro and in vivo analyses allow ...

Evaluation of Bioenergetic Function in Cerebral Vascular Endothelial Cells

The integrity of the blood-brain-barrier (BBB) is critical to prevent brain injury. Cerebral vascular endothelial (CVE) cells are one of the cell types that comprise the BBB; these cells have a very high-energy demand, which requires optimal mitochondrial function. In the case of disease or injury, the mitochondrial function in these cells can be altered, resulting in disease or&#160;the opening of the BBB. In this manuscript, we introduce a method to measure mitochondrial function in CVE cells by using whole, intact cells and a bioanalyzer. A mito-stress assay is used to challenge the cells that have been perturbed, either physically or chemically, and evaluate their bioenergetic function. Additionally, this method also provides a useful way to screen new therapeutics that have direct effects on mitochondrial function. We have optimized the cell density necessary to yield oxygen consumption rates that allow for the calculation of a variety of mitochondrial parameters, including ATP production, maximal respiration, and spare capacity. We also show the sensitivity of the assay by demonstrating that the introduction of the&#160;microRNA, miR-34a, leads to a pronounced and detectable decrease in mitochondrial activity. While the data shown in this paper is optimized for the bEnd.3 cell line, we have also optimized the protocol for primary CVE cells, further suggesting the utility in preclinical and clinical models.

Endothelial cell mitochondria are critical to maintain blood-brain-barrier integrity. We introduce a protocol to measure bioenergetic function in cerebral vascular endothelial cells.

The integrity of the blood-brain-barrier (BBB) is critical to prevent brain injury. Cerebral vascular endothelial (CVE) cells are one of the cell types ...

A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat model of ischemic stroke, differences in quantitative T1 and T2 MRI relaxation times (qT1 and qT2) between the ischemic lesion (delineated by low diffusion) and the contralateral non-ischemic hemisphere increase with time from stroke onset. The time dependency of MRI relaxation time differences is heuristically described by a linear function and thus provides a simple estimate of stroke onset time. Additionally, the volumes of abnormal qT1 and qT2 within the ischemic lesion increase linearly with time providing a complementary method for stroke timing. A (semi)automated computer routine based on the quantified diffusion coefficient is presented to delineate acute ischemic stroke tissue in rat ischemia. This routine also determines hemispheric differences in qT1 and qT2 relaxation times and the location and volume of abnormal qT1 and qT2 voxels within the lesion. Uncertainties associated with onset time estimates of qT1 and qT2 MRI data vary from &plusmn; 25 min to &plusmn; 47 min for the first 5 hours of stroke. The most accurate onset time estimates can be obtained by quantifying the volume of overlapping abnormal qT1 and qT2 lesion volumes, termed 'Voverlap' (&plusmn; 25 min) or by quantifying hemispheric differences in qT2 relaxation times only (&plusmn; 28 min). Overall, qT2 derived parameters outperform those from qT1. The current MRI protocol is tested in the hyperacute phase of a permanent focal ischemia model, which may not be applicable to transient focal brain ischemia.

A protocol for stroke onset time estimation in a rat model of stroke exploiting quantitative magnetic resonance imaging (qMRI) parameters is described. The procedure exploits diffusion MRI for delineation of the acute stroke lesion and quantitative T1 and T2 (qT1 and qT2) relaxation times for timing of stroke.

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat ...

Organotypic Hippocampal Slice Cultures As a Model to Study Neuroprotection and Invasiveness of Tumor Cells

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. This model is suitable for addressing different research questions that involve studies on neuroprotection, electrophysiological experiments on neurons, neuronal networks or tumor invasion. The hippocampal architecture and neuronal activity in multisynaptic circuits are well conserved in OHSC, even though the slicing procedure itself initially lesions and leads to formation of a glial scar. The scar formation alters presumably the mechanical properties and diffusive behavior of small molecules, etc. Slices allow the monitoring of time dependent processes after brain injury without animal surgery, and studies on interactions between various brain-derived cell types, namely astrocytes, microglia and neurons under both physiological and pathological conditions. An ambivalent aspect of this model is the absence of blood flow and immune blood cells. During the progression of the neuronal injury, migrating immune cells from the blood play an important role. As those cells are missing in slices, the intrinsic processes in the culture may be observed without external interference. Moreover, in OHSC the composition of the medium-external environment is precisely controlled. A further advantage of this method is the lower number of sacrificed animals compared to standard preparations. Several OHSC can be obtained from one animal making simultaneous studies with multiple treatments in one animal possible. For these reasons, OHSC are well suited to analyze the effects of new protective therapeutics after tissue damage or during tumor invasion. 
The protocol presented here describes a preparation method of OHSC that allows generating highly reproducible, well preserved slices that can be used for a variety of experimental research, like neuroprotection or tumor invasion studies.

Organotypic hippocampal slice cultures (OHSC) represent an in vitro model that simulates the in vivo situation very well. Here we describe a vibratome-based improved slicing protocol to obtain high quality slices for use in assessing the neuroprotective potential of novel substances or the biological behavior of tumor cells.

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. ...