The authors are thankful to the Vice Chancellor for Research of the Ardabil University of Medical Sciences (Ardabil, Iran) for the financial support (grant No: 9607).

All procedures were performed in accordance with the guidelines of Ardabil University of Medical Sciences Research Council for conducting animal studies (Ethical ID number: IR.ARUMS.REC.1394.08). In this visualized study, we used adult male Sprague-Dawley rats (300-350g) obtained from Pasture Institute (Tehran, Iran).
1. Anesthesia and Flowmetry
<ol>
	<li>Induce anesthesia using 4% isoflurane and maintain it with isoflurane (1-1.5%) in a mixture of nitrous oxide (70% v/v) and oxygen (30% v/v...

<ol>
	<li>Jin, 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=Protecting+against+cerebrovascular+injury:+contributions+of+12/15-lipoxygenase+to+edema+formation+after+transient+focal+ischemia.">Protecting against cerebrovascular injury: contributions of 12/15-lipoxygenase to edema formation after transient focal ischemia.</a> Stroke. 39 (9), 2538-2543 (2008).</li><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 (5), 399-415 (2003).</li><li>Tam, S. J., Watts, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Connecting+vascular+and+nervous+system+development:+angiogenesis+and+the+blood-brain+barrier.">Connecting vascular and nervous system development: angiogenesis and the blood-brain barrier.</a> Annu Rev Neurosci. 33, 379-408 (2010).</li><li>Zhang, 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=The+potential+use+of+H102+peptide-loaded+dual-functional+nanoparticles+in+the+treatment+of+Alzheimer's+disease.">The potential use of H102 peptide-loaded dual-functional nanoparticles in the treatment of Alzheimer's disease.</a> J Control Release. , (2014).</li><li>Obermeier, B., Daneman, R., Ransohoff, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development,+maintenance+and+disruption+of+the+blood-brain+barrier.">Development, maintenance and disruption of the blood-brain barrier.</a> Nat Med. 19 (12), 1584-1596 (2013).</li><li>Fang, W., 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=Attenuated+Blood-Brain+Barrier+Dysfunction+by+XQ-1H+Following+Ischemic+Stroke+in+Hyperlipidemic+Rats.">Attenuated Blood-Brain Barrier Dysfunction by XQ-1H Following Ischemic Stroke in Hyperlipidemic Rats.</a> Mol Neurobiol. 52 (1), 162-175 (2015).</li><li>Huang, 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=CXCR4+antagonist+AMD3100+protects+blood-brain+barrier+integrity+and+reduces+inflammatory+response+after+focal+ischemia+in+mice.">CXCR4 antagonist AMD3100 protects blood-brain barrier integrity and reduces inflammatory response after focal ischemia in mice.</a> Stroke. 44 (1), 190-197 (2013).</li><li>Omidi, Y., Barar, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impacts+of+blood-brain+barrier+in+drug+delivery+and+targeting+of+brain+tumors.">Impacts of blood-brain barrier in drug delivery and targeting of brain tumors.</a> Bioimpacts. 2 (1), 5-22 (2012).</li><li>Cho, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+blood-brain+barrier+model+for+in+vitro+studies+of+neurovascular+pathology.">Three-dimensional blood-brain barrier model for in vitro studies of neurovascular pathology.</a> Sci Rep. 5, (2015).</li><li>Barar, J., Rafi, M. A., Pourseif, M. M., Omidi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood-brain+barrier+transport+machineries+and+targeted+therapy+of+brain+diseases.">Blood-brain barrier transport machineries and targeted therapy of brain diseases.</a> Bioimpacts. 6 (4), 225-248 (2016).</li><li>Kaya, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnesium+sulfate+attenuates+increased+blood-brain+barrier+permeability+during+insulin-induced+hypoglycemia+in+rats.">Magnesium sulfate attenuates increased blood-brain barrier permeability during insulin-induced hypoglycemia in rats.</a> Can J Physiol Pharmacol. 79 (9), 793-798 (2001).</li><li>Pasban, E., Panahpour, H., Vahdati, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+oxygen+therapy+does+not+protect+the+brain+from+vasogenic+edema+following+acute+ischemic+stroke+in+adult+male+rats.">Early oxygen therapy does not protect the brain from vasogenic edema following acute ischemic stroke in adult male rats.</a> Sci Rep. 7 (1), 3221 (2017).</li><li>Haghnejad Azar, A., Oryan, S., Bohlooli, S., Panahpour, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alpha-Tocopherol+Reduces+Brain+Edema+and+Protects+Blood-Brain+Barrier+Integrity+following+Focal+Cerebral+Ischemia+in+Rats.">Alpha-Tocopherol Reduces Brain Edema and Protects Blood-Brain Barrier Integrity following Focal Cerebral Ischemia in Rats.</a> Med Princ Pract. 26 (1), 17-22 (2017).</li><li>Belayev, L., Busto, R., Zhao, W., Ginsberg, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+evaluation+of+blood-brain+barrier+permeability+following+middle+cerebral+artery+occlusion+in+rats.">Quantitative evaluation of blood-brain barrier permeability following middle cerebral artery occlusion in rats.</a> Brain Res. 739 (1-2), 88-96 (1996).</li><li>Bodsch, W., Hossmann, K. 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(48), (2011).</li><li>Hungerhuber, E., Zausinger, S., Westermaier, T., Plesnila, N., Schmid-Elsaesser, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+bilateral+laser+Doppler+fluxmetry+and+electrophysiological+recording+during+middle+cerebral+artery+occlusion+in+rats.">Simultaneous bilateral laser Doppler fluxmetry and electrophysiological recording during middle cerebral artery occlusion in rats.</a> J Neurosci Methods. 154 (1-2), 109-115 (2006).</li><li>Panahpour, H., Nouri, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-Ischemic+Treatment+with+candesartan+protect+from+cerebral+ischemic/reperfusioninjury+in+normotensive+rats.">Post-Ischemic Treatment with candesartan protect from cerebral ischemic/reperfusioninjury in normotensive rats.</a> Int J Pharm Pharm Sci. 4 (4), 286-289 (2012).</li><li>Panahpour, H., Dehghani, G. A., Bohlooli, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enalapril+attenuates+ischaemic+brain+oedema+and+protects+the+blood-brain+barrier+in+rats+via+an+anti-oxidant+action.">Enalapril attenuates ischaemic brain oedema and protects the blood-brain barrier in rats via an anti-oxidant action.</a> Clin Exp Pharmacol Physiol. 41 (3), 220-226 (2014).</li><li>Panahpour, H., Nekooeian, A. A., Dehghani, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blockade+of+Central+Angiotensin+II+AT1+Receptor+Protects+the+Brain+from+Ischemia/Reperfusion+Injury+in+Normotensive+Rats.">Blockade of Central Angiotensin II AT1 Receptor Protects the Brain from Ischemia/Reperfusion Injury in Normotensive Rats.</a> Iran J Med Sci. 39 (6), 536-542 (2014).</li><li>Panahpour, H., Nekooeian, A. A., Dehghani, G. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=125I-Antibody+Autoradiography+and+Peptide+Fragments+of+Albumin+in+Cerebral+Edema.">125I-Antibody Autoradiography and Peptide Fragments of Albumin in Cerebral Edema.</a> J Neurochem. 41 (1), 239-243 (1983).</li><li>Sandoval, K. E., Witt, K. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood-brain+barrier+tight+junction+permeability+and+ischemic+stroke.">Blood-brain barrier tight junction permeability and ischemic stroke.</a> Neurobiol Dis. 32 (2), 200-219 (2008).</li><li>Zhu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Baicalin+reduces+the+permeability+of+the+blood-brain+barrier+during+hypoxia+in+vitro+by+increasing+the+expression+of+tight+junction+proteins+in+brain+microvascular+endothelial+cells.">Baicalin reduces the permeability of the blood-brain barrier during hypoxia in vitro by increasing the expression of tight junction proteins in brain microvascular endothelial cells.</a> J Ethnopharmacol. 141 (2), 714-720 (2012).</li><li>Kucuk, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+losartan+on+the+blood-brain+barrier+permeability+in+long-term+nitric+oxide+blockade-induced+hypertensive+rats.">Effects of losartan on the blood-brain barrier permeability in long-term nitric oxide blockade-induced hypertensive rats.</a> Life Sci. 71 (8), 937-946 (2002).</li><li>Uyama, O., 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=Quantitative+evaluation+of+vascular+permeability+in+the+gerbil+brain+after+transient+ischemia+using+Evans+blue+fluorescence.">Quantitative evaluation of vascular permeability in the gerbil brain after transient ischemia using Evans blue fluorescence.</a> J Cereb Blood Flow Metab. 8 (2), 282-284 (1988).</li><li>Kleinig, T. J., Vink, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suppression+of+inflammation+in+ischemic+and+hemorrhagic+stroke:+therapeutic+options.">Suppression of inflammation in ischemic and hemorrhagic stroke: therapeutic options.</a> Curr Opin Neurol. 22 (3), 294-301 (2009).</li><li>Del Zoppo, G. J., Mabuchi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+microvessel+responses+to+focal+ischemia.">Cerebral microvessel responses to focal ischemia.</a> J Cereb Blood Flow Metab. 23 (8), 879-894 (2003).</li><li>Fluri, F., Schuhmann, M. 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Thus far, various methods such as autoradiography and detection of the radioactive tracers24,25, immunofluorescence microscopy26,27, and EB extravasation technique20,23 have been used to evaluate the blood-brain barrier damage. EB dye is strongly able to bind to the serum albumin and is used as a tracer for detecting vascular leakage and quantifyi...

Vasogenic brain edema due to blood-brain barrier (BBB) disruption remains an important complication of the ischemic stroke and a major determinant of the survival rate in the stroke patients1,2. The blood-brain barrier (BBB), which is formed by brain capillary endothelial cells (BCECs) and composed of distinct neurovascular components (e.g., tight junctions among BCECs, pericytes, astroglial, and neuronal cells3), provides a specialized and dynamic interface between the central nervous system (CNS) and peripheral blood-circulation4,5. Insults such as ischemia-reperfusion injuries could disrupt the functional integrity of the BBB and lead to subsequent penetration of circulating leukocytes into the brain parenchyma that ultimately trigger cerebral inflammation and primary brain injuries6,7. Animal models are needed for the exact detection of the dysfunction of BBB following occurrence of a stroke. Such models are of great importance for studying underlying pathophysiological mechanisms and introducing new neuroprotective strategies. In vitro cell culture-based models of the BBB have been highly developed and used for molecular study of the BBB physiopathology8,9,10. Nevertheless, in vivo animal models, which produce ischemic damage of the BBB similar to human clinical conditions, are also very worthwhile in this regard. Quantitative detection of the extravasation of Evans blue (EB) is a well-accepted and sensitive technique that has been used for assessment of the BBB integrity and function in neurodegenerative diseases, including ischemic stroke11,12,13,14. This method is cost-effective, feasible, reproducible, and completely applicable in any experimental laboratory. Its implementation does not require advanced equipment, such as radioactive tracers15 or magnetic resonance imaging (MRI)16, that are prerequisites for other methods. In this article, we comprehensively demonstrate basic technical processes of BBB assessment using EB extravasation in rat models of ischemic stroke.

<table border="0" cellpadding="0" cellspacing="0" width="829">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:208px;">Isoflurane</td>
			<td style="width:203px;">Piramal</td>
			<td style="width:225px;">AWN 34041100</td>
			<td style="width:193px;">20 - 25 &#176;C</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">2,3,5-Triphenyltetrazolium chloride (TTC)</td>
			<td>Molekula</td>
			<td>31216368</td>
			<td>4 years</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Sprague&#8211;Dawley rats&#160;</td>
			<td>Pasture Institute (Tehran, Iran)</td>
			<td></td>
			<td>300-350g</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Evans Blue&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>314-13-6</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Trichloroacetic acid&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>76-03-9</td>
			<td>2 years</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Bupivacaine HCl (0.5%)</td>
			<td>Delpharm Tours</td>
			<td></td>
			<td>below&#160; 25 &#176;C</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Bupernorphine</td>
			<td>Exir (Iran)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Sodium Carbonate</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>497-19-8</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Sodium chloride&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Di- Sodium hydrogen phosphate</td>
			<td>EMD Millipore&#160;</td>
			<td>231-448-7</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Potassium chloride</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>&#160;7447-40-7</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:208px;">Ethanol&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>64-17-5</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">silicone(Xantopren)</td>
			<td>Heraeus</td>
			<td>EN ISO 4823</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Activator universal plus</td>
			<td>Heraeus</td>
			<td>66037445</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Micro-Dissecting forceps</td>
			<td>Stoelting</td>
			<td>52100-41</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Spring Scisors</td>
			<td>Stoelting</td>
			<td>52130-00</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Operating&#160; Scissors</td>
			<td>Roboz</td>
			<td>52140-70</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Brain matrix&#160;</td>
			<td>Stoelting</td>
			<td>51390</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Anesthesia Machine for Small Animals |</td>
			<td>&#160;Kent Scientific</td>
			<td>SS-01</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Power Lab system</td>
			<td>AD Instruments</td>
			<td>ML880</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Laser Doppler flowmeter</td>
			<td>AD Instruments</td>
			<td>ML191</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Heating feed back system</td>
			<td>Harvard Appratus</td>
			<td>72-7560</td>
			<td style="width:193px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Vascular micro clamp</td>
			<td>FineScience Tools</td>
			<td>18055-03</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Silk 5-0 suture thread</td>
			<td>Ethicon</td>
			<td>682G</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Ethilon 4-0 suture thread&#160;</td>
			<td>Ethicon</td>
			<td>EH6740G</td>
			<td></td>
		</tr>
	</tbody>
</table>

an in vivo assessment of blood-brain barrier disruption in a rat model of ischemic stroke

Ischemic stroke leads to vasogenic cerebral edema and subsequent primary brain injury, which is mediated through destruction of the blood-brain barrier (BBB). Rats with induced ischemic stroke were established and used as in vivo models to investigate the functional integrity of the BBB. Spectrophotometric detection of Evans blue (EB) in the brain samples with ischemic injury could provide reliable justification for the research and development of novel therapeutic modalities. This method generates reproducible results, and is applicable in any laboratory without a need for special equipment. Here, we present a visualized and technical guideline on the detection of the extravasation of EB following induction of ischemic stroke in rats.

There was no significant difference in EB levels in the right hemisphere versus the left hemisphere of the sham-operated rats (1.06 &#177; 0.1 &#181;g/g and 1.1 &#177; 0.09 &#181;g/g, respectively). As shown in Figures 2A-2B, induction of transient ischemia (90 min ischemia/ 24 h reperfusion) caused a significant difference in EB levels (10.41 &#177; 0.84 &#181;g/g, p &#60;0.001) in the left hemisphere of ischemic rats, as compared to the respective hemisphere in...

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An In Vivo Assessment of Blood-Brain Barrier Disruption in a Rat Model of Ischemic Stroke

The overall goal of this procedure is to provide a highly reproducible technique for in vivo assessment of the blood-brain barrier disruption in rat models of ischemic stroke.

An In Vivo Assessment of Blood-Brain Barrier Disruption in a Rat Model of Ischemic Stroke

Ischemic stroke leads to vasogenic cerebral edema and subsequent primary brain injury, which is mediated through destruction of the blood-brain barrier ...

The overall goal of this procedure is to present a highly reproducible method of an in vivo assessment of the blood-brain barrier disruption in a react model of ischemic stroke. This is accomplished by induction of ischemic stroke using intraluminal filament for middle cerebral artery occlusion in the left side of the brain. The next step of the procedure is cannulation of the jugular vein external branch and injection of Evans Blue dye at the end of the middle cerebral artery occlusion and beginning of the reperfusion period.Twenty-four hours later under deep anesthesia, the animal's circulation system is washed out from Evans Blue and the brain is removed. Then two cerebral hemispheres are separated, homogenized, and centrifuged, and ultimately supernatants of tissues is used to measure Evans Blue concentration with a spectrophotometer. Anesthesia and flowmetry.Induce anesthesia using 4%isoflurane and maintain it with isoflurane 1-1.5%in a mixture of 70%nitrous oxide and 13%oxygen for the duration of the surgery. Place anesthetized animal in the prone posture on feedback control heating blanket and maintain the body temperature at normal physiological range by means of a rectal probe connected to this heating unit. Shave surgery region in the left side of the skull and apply Betadine solution using a gauze pad to disinfect the skin.Replace with a sterile pad containing 70%ethanol and repeat both steps with three cycles. Make a one centimeter long skin incision on the skull extending from the lateral canthus of the left eye to the base of the left ear and dissect left temporalis muscle to expose the skull. Then cut a small hole at five millimeter lateral and one millimeter posterior to the bregma to ease placement of the tip of the Doppler flowmeter pencil probe.Turn the rat from prone to supine position and then put the laser pencil probe into the previously drilled skull hole to monitor the regional cerebral blood flow. Record each animal's baseline regional cerebral blood flow and consider it as 100%Induction of the focal cerebral ischemia. Shave the neck region and disinfect the skin with Betadine solution and 70%ethanol.Inject 0.2 milliliter of 0.5%bupivacaine subcutaneously in the surgery site for analgesia. Make a two centimeter long surgical incision in the ventral surface of the neck to access the left common carotid artery. Isolate the common carotid artery from the neighboring fascia and the vagus nerve to access bifurcation of the external carotid artery and the internal carotid artery.Ligate permanently either the left common carotid artery or the external carotid artery employing a 5-0 sac suture and dissect internal carotid artery to the level of the pterygopalatine artery. Loosely place a 5-0 sac suture around common carotid artery and then temporarily clamp internal carotid artery with a vascular micro clip. Make a small incision on the common carotid artery prior to previously placed loose tie and then insert a 4-0 silicone-coated nylon suture into the luminal space of internal carotid artery and tighten the suture around the common carotid artery to secure the nylon suture and prevent blood leaking.Remove the vascular micro clip from the internal carotid artery. Then advance silicone-coated intraluminal filament until observing a marked decline in the regional cerebral blood flow that indicates occlusion of the middle cerebral artery origin. Notably, medial cerebral artery occlusion is started where a decrease in the regional cerebral blood flow of more than 80%is detected.In this model, we temporarily block the pterygopalatine artery using a micro clamp to guide the filament correctly into the atrial path. Note, this step is very important for the success of the medial cerebral artery occlusion. Jugular vein cannulation and Evans Blue injection.Make a one centimeter longitudinal incision in the neck to the left side of the midline and then bluntly dissect away superficial fascia to access the external branch of the left jugular vein. Then permanently ligate the cornual end of the jugular vein with 5-0 sac suture. Loosely place two ties around the vein and then temporarily clamp the cardiac end of the jugular vein with vascular micro clamp.Make a small incision on the jugular vein with two sutures and then insert heparinized serum-filled catheter into the luminal space of the vein and advance it approximately 10 millimeters. Afterward, tighten the ligatures around the vein to secure the catheter and prevent bleeding. Inject small amount of serum to avoid collapsing of the vein.At the end of ischemic period, that is 90 minutes, start reperfusion by withdrawing the intraluminal suture. At the beginning of reperfusion period, slowly inject Evans Blue dye one milliliter per kilogram of 2%solution in saline over a five-minute period. Subsequently, wash the cannula by injection of 0.5 milliliter normal saline and withdraw the injection cannula from the vein.Note the color change of the tissue after Evans Blue injection. Finally, suture the neck and head incisions and place the animal in a recovery cage. Assessment of the blood-brain barrier permeability.After 24 hours of reperfusion, deeply anesthetize animal with sodium thiopental. Then open thoracic cavity by making a small hole beneath the sternum. Make a small opening in the right atrium and inject 250 milliliters pre-warmed saline through the left ventricle for 15 minutes to wash Evans Blue away from the circulation until the normal saline which is left out from the atrium becomes colorless.Immediately remove the brain from the skull and place in the brain matrix. Dissect olfactory bulb and cerebellum and then using a clean razor blade, separate the right hemisphere of the brain from the left along the midline. Weigh each hemisphere and homogenize them separately in 2.5 milliliter phosphate buffered saline and then mix it with 2.5 milliliters of 16%trichloroacetic acid for two minutes using a vortex machine.Centrifuge brain samples for 30 minutes and allow them to cool down in the fridge for 10 minutes. Use the supernatants to estimate the Evans Blue absorbance by a spectrophotometer at 610 nanometers. Representative results.In sham-operated animals, Evans Blue concentration of tissues prepared for both hemispheres of the brain are very small and there is no significant difference in comparison with each other. Induction of ischemia over 90 minutes followed by 24 reperfusion caused a significant increase in Evans Blue levels in the lesioned hemisphere of the brain in ischemic rats. Collectively, these findings indicate that under normal conditions, Evans Blue cannot readily cross the blood-brain barrier into cerebral parenchyma and cerebral ischemic insults induced the extravasation of Evans Blue through an in-house permeability of blood-brain barrier.The photograph shows the brain in the sham-operated and ischemic animals. Note, the intensity of Evans Blue extravasation in the brain tissue that is blue color arises from extent of the blood-brain barrier disruption in the lesioned hemisphere.Conclusion. In vivo assessment of the blood-brain barrier allows researcher to study possible pathophysiological mechanisms of ischemia-induced vasogenic brain edema and to find new therapeutic interventions.This technique is simple and reliable. A researcher needs to take into account some technical points to further enhance the performance of the technique and ensure upon its accuracy. Constant recording of the regional cerebral blood flow with laser Doppler flowmeter and using of silicone-coated filament can increase the MCAO success rate and reduce the mortality rate.dosage and time point of injection are two essential parameters for obtaining reliable results due to the dynamic nature of blood-brain barrier following ischemic insults.

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Research

JoVE Journal

Neuroscience

Generation of an Immortalized Murine Brain Microvascular Endothelial Cell Line as an In Vitro Blood Brain Barrier Model

Epithelial and endothelial cells (EC) are building paracellular barriers which protect the tissue from the external and internal environment. The blood-brain barrier (BBB) consisting of EC, astrocyte end-feet, pericytes and the basal membrane is responsible for the protection and homeostasis of the brain parenchyma. In vitro BBB models are common tools to study the structure and function of the BBB at the cellular level. A considerable number of different in vitro BBB models have been established for research in different laboratories to date. Usually, the cells are obtained from bovine, porcine, rat or mouse brain tissue (discussed in detail in the review by Wilhelm et al. 1). Human tissue samples are available only in a restricted number of laboratories or companies 2,3. While primary cell preparations are time consuming and the EC cultures can differ from batch to batch, the establishment of immortalized EC lines is the focus of scientific interest.
Here, we present a method for establishing an immortalized brain microvascular EC line from neonatal mouse brain. We describe the procedure step-by-step listing the reagents and solutions used. The method established by our lab allows the isolation of a homogenous immortalized endothelial cell line within four to five weeks. The brain microvascular endothelial cell lines termed cEND 4 (from cerebral cortex) and cerebEND 5 (from cerebellar cortex), were isolated according to this procedure in the F&ouml;rster laboratory and have been effectively used for explanation of different physiological and pathological processes at the BBB. Using cEND and cerebEND we have demonstrated that these cells respond to glucocorticoid- 4,6-9 and estrogen-treatment 10 as well as to pro-infammatory mediators, such as TNFalpha 5,8. Moreover, we have studied the pathology of multiple sclerosis 11 and hypoxia 12,13 on the EC-level. The cEND and cerebEND lines can be considered as a good tool for studying the structure and function of the BBB, cellular responses of ECs to different stimuli or interaction of the EC with lymphocytes or cancer cells.

Generation of an Immortalized Murine Brain Microvascular Endothelial Cell Line as an In Vitro Blood Brain Barrier Model

This method describes how to isolate and immortalize microvascular endothelial cells from mouse brain. We describe a step-by-step protocol starting from the homogenization of brain tissue, digestion steps, seeding and immortalization of the cells. Usually, it takes about five weeks to obtain a homogenous, immortalized microvascular endothelial cell line.

Epithelial and endothelial cells (EC) are building paracellular barriers which protect the tissue from the external and internal environment. The ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains technically challenging. One approach, Activation-Induced Manganese-enhanced MRI (AIM MRI), has been used successfully to map neuronal activity in rodents 1-5. In AIM MRI, Mn2+ acts a calcium analog and accumulates in depolarized neurons 6,7. Because Mn2+ shortens the T1 tissue property, regions of elevated neuronal activity will enhance in MRI. Furthermore, Mn2+ clears slowly from the activated regions; therefore, stimulation can be performed outside the magnet prior to imaging, enabling greater experimental flexibility. However, because Mn2+ does not readily cross the blood-brain barrier (BBB), the need to open the BBB has limited the use of AIM MRI, especially in mice.
One tool for opening the BBB is ultrasound. Though potentially damaging, if ultrasound is administered in combination with gas-filled microbubbles (i.e., ultrasound contrast agents), the acoustic pressure required for BBB opening is considerably lower. This combination of ultrasound and microbubbles can be used to reliably open the BBB without causing tissue damage 8-11.
Here, a method is presented for performing AIM MRI by using microbubbles and ultrasound to open the BBB. After an intravenous injection of perflutren microbubbles, an unfocused pulsed ultrasound beam is applied to the shaved mouse head for 3 minutes. For simplicity, we refer to this technique of BBB Opening with Microbubbles and UltraSound as BOMUS 12. Using BOMUS to open the BBB throughout both cerebral hemispheres, manganese is administered to the whole mouse brain. After experimental stimulation of the lightly sedated mice, AIM MRI is used to map the neuronal response.
To demonstrate this approach, herein BOMUS and AIM MRI are used to map unilateral mechanical stimulation of the vibrissae in lightly sedated mice 13. Because BOMUS can open the BBB throughout both hemispheres, the unstimulated side of the brain is used to control for nonspecific background stimulation. The resultant 3D activation map agrees well with published representations of the vibrissae regions of the barrel field cortex 14. The ultrasonic opening of the BBB is fast, noninvasive, and reversible; and thus this approach is suitable for high-throughput and/or longitudinal studies in awake mice.

A technique is described for broadly opening the blood-brain barrier in the mouse using microbubbles and ultrasound. Using this technique, manganese can be administered to the mouse brain. Because manganese is an MRI contrast agent that accumulates in depolarized neurons, this approach enables imaging of neuronal activity.

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay between perturbed BBB homeostasis and the pathogenesis of brain disorders needs further investigation, the development and validation of a reliable procedure to accurately detect BBB alterations may be crucial and represent a useful tool for potentially predicting disease progression and developing targeted therapeutic strategies.
Here, we present an easy and efficient procedure for evaluating BBB leakage in a neurodegenerative condition like that occurring in a preclinical mouse model of Huntington disease, in which defects in the permeability of BBB are clearly detectable precociously in the disease. Specifically, the high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin, which is able to cross the BBB only when the latter is impaired, is acutely infused into a mouse jugular vein and its distribution in the vascular or parenchymal districts is then determined by fluorescence microscopy.
Accumulation of green fluorescent-albumin in the brain parenchyma functions as an index of aberrant BBB permeability and, when quantitated by using Image J processing software, is reported as Green Fluorescence Intensity.

In this study, we present an easy and efficient procedure for evaluating the disruption of the blood-brain barrier under neurodegenerative conditions. To achieve our objective, we infused high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin into mouse jugular vein and evaluated its leakage into the brain parenchyma by fluorescence microscopy.

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay ...

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains brain homeostasis. The principal sites of the barrier are endothelial cells of the brain capillaries whose barrier function results from tight intercellular junctions and efflux transporters expressed on the plasma membrane. This function is regulated by pericytes and astrocytes that together form the neurovascular unit (NVU). Several neurological diseases such as stroke, Alzheimer&#39;s disease (AD), brain tumors are associated with an impaired BBB function. Assessment of the BBB permeability is therefore crucial in evaluating the severity of the neurological disease and the success of the treatment strategies employed.
We present here a simple yet robust permeability assay that have been successfully applied to several mouse models both, genetic and experimental. The method is highly quantitative and objective in comparison to the tracer fluorescence analysis by microscopy that is commonly applied. In this method, mice are injected intraperitoneally with a mix of aqueous inert fluorescent tracers followed by anesthetizing the mice. Cardiac perfusion of the animals is performed prior to harvesting brain, kidneys or other organs. Organs are homogenized and centrifuged followed by fluorescence measurement from the supernatant. Blood drawn from the cardiac puncture just before perfusion serves for normalization purpose to the vascular compartment. The tissue fluorescence is normalized to the wet weight and serum fluorescence to obtain a quantitative tracer permeability index. For additional confirmation, the contralateral hemi-brain preserved for immunohistochemistry can be utilized for tracer fluorescence visualization purposes.

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Here we present a mouse brain vascular permeability assay using intraperitoneal injection of fluorescent tracers followed by perfusion that is applicable to animal models of blood-brain barrier dysfunction. One hemi-brain is used for assessing permeability quantitatively and the other for tracer visualization/immunostaining. The procedure takes 5 - 6 h for 10 mice.

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains ...

A Preclinical Model to Assess Brain Recovery After Acute Stroke in Rats

The purpose of this study was to establish and validate an animal brain ischemia model in the recovery and sequela stages. A middle cerebral artery occlusion/reperfusion (MCAO/R) model in male Sprague-Dawley rats was chosen. By changing the rat&#39;s weight (260&#8722;330 g), the thread bolt type (2636/2838/3040/3043) and the brain infarct time (2-3 h), a higher Longa&#39;s score, a larger infarct volume and a greater model success ratio were screened using the Longa&#39;s score and TTC staining. The optimum model condition (300 g, 3040 thread bolt, 3 h brain infarct time) was acquired and used in a 1-90 day observation period after reperfusion via assessment of sensorimotor functions and infarct volume. At these conditions, the bilateral asymmetry test had a significant difference from 1 to 90 days, and the grid-walking test had a significant difference from 1 to 60 days; both differences could be a suitable sensorimotor functional test. Thus, the most appropriate condition of a novel rat model in the recovery and sequela stages of brain ischemia was found: 300 g rats that underwent MCAO with a 3040 thread bolt for a 3 h brain infarct and then reperfused. The appropriate sensorimotor functional tests were a bilateral asymmetry test and a grid-walking test.

The&#160;purpose of this study is to establish and validate an animal model for research in the recovery and sequela stages of brain ischemia by testing brain infarction and sensorimotor function after middle cerebral artery occlusion/reperfusion (MCAO/R) after 1-90 days in rats.

The purpose of this study was to establish and validate an animal brain ischemia model in the recovery and sequela stages. A middle cerebral artery ...

A Benchtop Approach to the Location Specific Blood Brain Barrier Opening using Focused Ultrasound in a Rat Model

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic delivery including precise localization to a target brain region and reduction of off target side effects. However, stereotaxic surgery is highly invasive which limits its translational efficacy, requires long recovery times, and provides challenges when targeting multiple brain regions. Focused ultrasound (FUS) can be used in combination with circulating microbubbles to transiently open the blood brain barrier (BBB) in millimeter sized regions. This allows intracranial localization of systemically delivered agents that cannot normally cross the BBB. This technique provides a noninvasive alternative to stereotaxic surgery. However, to date this technique has yet to be widely adopted in neuroscience laboratories due to the limited access to equipment and standardized methods. The overall goal of this protocol is to provide a benchtop approach to FUS BBB opening (BBBO) that is affordable and reproducible and can therefore be easily adopted by any laboratory.

Focused ultrasound with microbubble agents can open the blood brain barrier focally and transiently. This technique has been used to deliver a wide range of agents across the blood brain barrier. This article provides a detailed protocol for the localized delivery to the rodent brain with or without MRI guidance.

Stereotaxic surgery is the gold standard for localized drug and gene delivery to the rodent brain. This technique has many advantages over systemic ...

Measuring Post-Stroke Cerebral Edema, Infarct Zone and Blood-Brain Barrier Breakdown in a Single Set of Rodent Brain Samples

One of the most common causes of morbidity and mortality worldwide is ischemic stroke. Historically, an animal model used to stimulate ischemic stroke involves middle cerebral artery occlusion (MCAO). Infarct zone, brain edema and blood-brain barrier (BBB) breakdown are measured as parameters that reflect the extent of brain injury after MCAO. A significant limitation to this method is that these measurements are normally obtained in different rat brain samples, leading to ethical and financial burdens due to the large number of rats that need to be euthanized for an appropriate sample size. Here we present a method to accurately assess brain injury following MCAO by measuring infarct zone, brain edema and BBB permeability in the same set of rat brains. This novel technique provides a more efficient way to evaluate the pathophysiology of stroke.

This protocol describes a novel technique of measuring the three most important parameters of ischemic brain injury on the same set of rodent brain samples. Using only one brain sample is highly advantageous in terms of ethical and economic costs.

One of the most common causes of morbidity and mortality worldwide is ischemic stroke. Historically, an animal model used to stimulate ischemic stroke ...

A Rat Model of EcoHIV Brain Infection

It has been well studied that the EcoHIV infected mouse model is of significant utility in investigating HIV associated neurological complications. Establishment of the EcoHIV infected rat model for studies of drug abuse and neurocognitive disorders, would be beneficial in the study of neuroHIV and HIV-1 associated neurocognitive disorders (HAND). In the present study, we demonstrate the successful creation of a rat model of active HIV infection using chimeric HIV (EcoHIV). First, the lentiviral construct of EcoHIV was packaged in cultured 293 FT cells for 48 hours. Then, the conditional medium was concentrated and titered. Next, we performed bilateral stereotaxic injections of the EcoHIV-EGFP into F344/N rat brain tissue. One week after infection, EGFP fluorescence signals were detected in the infected brain tissue, indicating that EcoHIV successfully induces an active HIV infection in rats. In addition, immunostaining for the microglial cell marker, Iba1, was performed. The results indicated that microglia were the predominant cell type harboring EcoHIV. Furthermore, EcoHIV rats exhibited alterations in temporal processing, a potential underlying neurobehavioral mechanism of HAND as well as synaptic dysfunction eight weeks after infection. Collectively, the present study extends the EcoHIV model of HIV-1 infection to the rat offering a valuable biological system to study HIV-1 viral reservoirs in the brain as well as HAND and associated comorbidities such as drug abuse.

Here, we present a protocol to establish a new rat model of active HIV infection using chimeric HIV (EcoHIV), which is critical for enhancing our understanding of HIV-1 viral reservoirs in the brain and offering a system to study HIV-associated neurocognitive disorders and associated comorbidities (i.e., drug abuse).

It has been well studied that the EcoHIV infected mouse model is of significant utility in investigating HIV associated neurological complications. ...

Induction and Assessment of Levodopa-induced Dyskinesias in a Rat Model of Parkinson's Disease

Levodopa (L-DOPA) remains the gold-standard therapy used to treat Parkinson&#39;s disease (PD) motor symptoms. However, unwanted involuntary movements known as L-DOPA-induced dyskinesias (LIDs) develop with prolonged use of this dopamine precursor.&#160;It is estimated that the incidence of LIDs escalates to approximately 90% of individuals with PD within 10&#8211;15 years of treatment. Understanding the mechanisms of this malady and developing both novel and effective anti-dyskinesia treatments requires consistent and accurate modeling for pre-clinical testing of therapeutic interventions. A detailed method for reliable induction and comprehensive rating of LIDs following 6-OHDA-induced nigral lesioning in a rat model of PD is presented here. Dependable LID assessment in rats provides a powerful tool that can be readily utilized across laboratories to test emerging therapies focused on reducing or eliminating this common treatment-induced burden for individuals with PD.

Induction and Assessment of Levodopa-induced Dyskinesias in a Rat Model of Parkinson&#039;s Disease

This article describes methods to induce and evaluate levodopa-induced dyskinesias in a rat model of Parkinson&#39;s disease. The protocol offers detailed information regarding the intensity and frequency of a range of dyskinetic behaviors, both dystonic and hyperkinetic, providing a reliable tool to test treatments targeting this unmet medical need.

Levodopa (L-DOPA) remains the gold-standard therapy used to treat Parkinson&#39;s disease (PD) motor symptoms. However, unwanted involuntary movements ...

Transendothelial Resistance Measurement to Assess Cell Barrier Integrity

Barrier Functional Integrity Recording on bEnd.3 Vascular Endothelial Cells via Transendothelial Electrical Resistance Detection

The blood-brain barrier (BBB) is a dynamic physiological structure composed of microvascular endothelial cells, astrocytes, and pericytes. By coordinating the interaction between restricted transit of harmful substances, nutrient absorption, and metabolite clearance in the brain, the BBB is essential in preserving central nervous system homeostasis. Building in vitro models of the BBB is a valuable tool for exploring the pathophysiology of neurological disorders and creating pharmacological treatments. This study describes a procedure for creating an in vitro monolayer BBB cell model by seeding bEnd.3 cells into the upper chamber of a 24-well plate. To assess the integrity of cell barrier function, the conventional epithelial cell voltmeter was used to record the transmembrane electrical resistance of normal cells and CoCl2-induced hypoxic cells in real-time. We anticipate that the above experiments will provide effective ideas for the creation of in vitro models of BBB and drugs to treat disorders of central nervous system diseases.

Author Spotlight: Applications of TEER Detection to Assess Cell Barrier Integrity 

This protocol describes a dependable and efficient in vitro model of the brain blood barrier. The method uses mouse cerebral vascular endothelial cells bEnd.3 and measures transmembrane electrical resistance.

The blood-brain barrier (BBB) is a dynamic physiological structure composed of microvascular endothelial cells, astrocytes, and pericytes. By coordinating ...