This work was supported by grants from the National Institutes of Health (R01-NS084941) and the Arizona Biomedical Research Commission (ADHS16-162406) to PTR. WA has received past support from a pre-doctoral appointment to a National Institutes of Health Training Grant (T32-HL007249).

All procedures outlined below have been approved by an Institutional Animal Care and Use Committee (IACUC) and conform to National Institutes of Health (NIH) and Animal Research: Reporting In Vivo Experiments (ARRIVE) guidelines. The procedural flow for the protocol is depicted in Figure 1.
1. Set-up for the Procedure
<ol>
	<li>Prepare the brain microvessel buffer (BMB). Start by weighing 54.66 g D-mannitol, 1.90 g EGTA, and 1.46 g 2-amino-2-(hydroxymethyl)-1,3-propanediol (i.e., Tris) base into a clean beaker. Add 1.0 L of deionized water. Mix the components of the BMB buffer using a magnetic stirrer. Once the solution has been thoroughly mixed, adjust the pH to 7.4 using 1.0 M HCl.</li>
	<li>Prepare 26% dextran (MW 75,000) solution (w/v) prior to anesthetizing animals. Prepare the dextran solution as described in the following steps. 
	NOTE: It is critically important to prepare this solution ahead of time because dextran can take approximately 1.5-2 h to dissolve in aqueous buffer.
	<ol>
		<li>Weigh out the powdered dextran (26 g per 100 mL buffer) into a clean beaker.</li>
		<li>Measure out the appropriate volume of BMB and dispense into a separate, clean beaker.</li>
		<li>Slowly pour BMB into the beaker containing powdered dextran. Manually mix the powdered dextran during pouring of BMB using a glass stir rod.</li>
		<li>Adjust the pH to 7.4 with 1.0 M HCl immediately prior to use. 
		NOTE: A typical isolation of brain microvessels from 12 individual Sprague-Dawley rats (male or female; 3 months of age; 200-250 g each) requires 200 mL of dextran solution (i.e., 52 g dextran in 200 mL of BMB).</li>
	</ol>
	</li>
</ol>
2. Extraction of Brain Tissue from Sprague-Dawley Rats
<ol>
	<li>Following the desired experimental treatment, anesthetize Sprague-Dawley rats using ketamine (50 mg/kg; 2.5 mL/kg i.p.) and xylazine (10 mg/mL; 2.5 mL/kg I,p.). Dilute ketamine and xylazine in 0.9% saline to final concentrations of 20 mg/mL and 4.0 mg/mL respectively. Euthanize animals by decapitation using a sharpened guillotine in accordance with IACUC guidelines. Use the same procedure for both male and female Sprague-Dawley rats.</li>
	<li>Resect the skin from the rat skull by making a single transverse cut using surgical scissors.</li>
	<li>Using rongeurs, carefully remove the skull plate and expose the brain.</li>
	<li>Remove the brain using a spatula. Detach the cerebrum and place the isolated brain tissue into a 50 mL conical tube containing 5 mL of BMB. Add 1.0 &#956;L of protease inhibitor cocktail per 1.0 mL of BMB buffer immediately prior to use.</li>
</ol>
3. Brain Processing
<ol>
	<li>Transfer the brain tissue from the 50 mL conical tube to a clean petri dish.</li>
	<li>Using forceps, gently roll the brain on 12.5 cm diameter filter paper to remove outer meninges, which are loosely adhered to the cerebral cortex. Gently press the brain tissue against filter paper and roll the tissue again. Turn the filter paper frequently during this step.</li>
	<li>Separate the choroid plexus from the cerebral hemispheres using forceps. 
	NOTE: The choroid plexus appears as a clear membranous tissue localized to the surface of the cerebral ventricles.</li>
	<li>Gently flatten the brain tissue and remove remaining meninges and olfactory bulbs using forceps.</li>
	<li>Place the cortical brain tissue into a chilled glass mortar. Add 5.0 mL of BMB containing protease inhibitor cocktail to the mortar.</li>
	<li>Using an overhead power homogenizer, homogenize the brain tissue using 15 up and down strokes at 3,700&#160;rpm. Perform homogenization using a 10 mL mortar and pestle tissue grinder. Between homogenization of each individual sample, clean the pestle using 70% ethanol. 
	NOTE: Homogenization strokes should be consistent in terms of pace and magnitude.</li>
	<li>Pour the homogenate into labeled centrifuge tubes.</li>
</ol>
4. Centrifugation Steps
<ol>
	<li>Add 8.0 mL of 26% dextran solution to each labeled centrifuge tube containing brain homogenate.</li>
	<li>Invert the tube twice and then thoroughly vortex the sample. Conduct the vortexing of each sample using multiple angles to ensure a thorough mixing of brain homogenate solution with 26% dextran solution.</li>
	<li>Centrifuge samples at 5,000 x g for 15 min at 4 &#176;C. 
	NOTE: For some analyses, it is useful to compare brain microvessels with brain parenchyma. Should the assessment of protein expression in brain parenchyma be required, the supernatant from this centrifugation step (i.e., brain parenchymal fraction) can be collected and stored at -80 &#176;C for future use.</li>
	<li>Remove the supernatant using a vacuum aspirator and glass Pasteur pipette. 
	NOTE: Caution must be taken to not disturb the pellet. Otherwise, quantity of the brain microvessels collected will be reduced, which will significantly decrease the protein yield from this procedure.</li>
	<li>Resuspend the pellet in 5.0 mL of BMB containing protease inhibitor cocktail (i.e., 1.0 &#956;L protease inhibitor cocktail per 1.0 mL of BMB buffer). Vortex the pellet to ensure thorough mixing.</li>
	<li>Add 8.0 mL of 26% dextran to each centrifuge tube and vortex as described in steps 4.1-4.2 of this protocol.</li>
	<li>Centrifuge samples at 5,000 x g for 15 min at 4 &#176;C.</li>
	<li>Using a vacuum flask and glass pipette, aspirate supernatant and ensure that pellet containing brain microvessel is not disrupted. 
	NOTE: Excess material that has adhered to the tube wall does not contain microvessels and should be carefully cleaned and removed.</li>
	<li>Repeat steps 4.5 through 4.8 an additional two times.</li>
	<li>Once 4 dextran centrifugation steps have been completed, add 5.0 mL of BMB to each pellet and vortex to resuspend the sample. 
	NOTE: Following completion of step 4.10, whole microvessels can be collected for analysis of protein localization. This can be accomplished by taking a 50 &#956;L aliquot of re-suspended microvessel pellet and smearing on a glass microscope slide. Microvessels are then heat-fixed at 95 &#176;C for 10 min on a heating block followed by fixation in ice-cold ethanol for an additional 10 min. Slides can then be stored at 4 &#176;C until required for imaging studies.</li>
</ol>
5. Ultracentrifugation to Prepare Samples of Total Brain Microvascular Membranes
<ol>
	<li>Transfer samples to the chilled glass homogenizer.</li>
	<li>Using an overhead power homogenizer, homogenize brain tissue using 8-10 up and down strokes at 3,000 rpm. Homogenization is conducted using a 10 mL mortar and pestle tissue grinder. Clean the pestle using 70% ethanol following homogenization of each individual sample.</li>
	<li>Transfer samples to clean ultracentrifuge tubes. Number and weigh each individual tube. Balance and pair the tubes prior to loading into the ultracentrifuge rotor. 
	NOTE: All weighing and pairing of ultracentrifuge tubes must be conducted with the caps on to ensure accurate measurement of tube weights.</li>
	<li>Centrifuge samples at 150,000 x g for 1 h at 4 &#176;C.</li>
	<li>Using a vacuum flask and glass Pasteur pipette, aspirate supernatant using care not to disrupt the capillary membrane pellet.</li>
	<li>Based on the pellet size, add an appropriate volume of storage buffer, which is comprised of deionized water and BMB in a 1:1 (v/v) ratio. Typically, pellets are resuspended in 400-500 &#956;L of storage buffer. Add protease inhibitor cocktail to the storage buffer in a ratio of 1.0 &#956;L per 1.0 mL of storage buffer.</li>
	<li>Vortex samples to resuspend pellet in storage buffer.</li>
	<li>Using a glass Pasteur pipette, transfer capillary membrane samples to a labeled 1.5 mL microcentrifuge tube.</li>
	<li>Pass sample through a needle syringe 5x to ensure the sample is thoroughly mixed and that no cellular aggregates exist.</li>
	<li>Store samples at -80 &#176;C until required for analysis. 
	NOTE: Protein content of each microvessel membrane sample is measured using the Bradford method.</li>
</ol>

<ol>
	<li>Rolfe, D. F., Brown, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+energy+utilization+and+molecular+origin+of+standard+metabolic+rate+in+mammals.">Cellular energy utilization and molecular origin of standard metabolic rate in mammals.</a> Physiol Rev. 77 (3), 731-758 (1997).</li><li>Brzica, H., Abdullahi, W., Ibbotson, K., Ronaldson, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+Transporters+in+Central+Nervous+System+Drug+Delivery+and+Blood-Brain+Barrier+Protection:+Relevance+to+Treatment+of+Stroke.">Role of Transporters in Central Nervous System Drug Delivery and Blood-Brain Barrier Protection: Relevance to Treatment of Stroke.</a> J Cent Nerv Syst Dis. 9, 1179573517693802 (2017).</li><li>Ronaldson, P. T., Davis, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+transporters:+promoting+blood-brain+barrier+repair+in+response+to+oxidative+stress+injury.">Targeting transporters: promoting blood-brain barrier repair in response to oxidative stress injury.</a> Brain Res. 1623, 39-52 (2015).</li><li>Witt, K. A., Mark, K. S., Hom, S., Davis, T. P. <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+hypoxia-reoxygenation+on+rat+blood-brain+barrier+permeability+and+tight+junctional+protein+expression.">Effects of hypoxia-reoxygenation on rat blood-brain barrier permeability and tight junctional protein expression.</a> Am J Physiol Heart Circ Physiol. 285 (6), H2820-H2831 (2003).</li><li>McCaffrey, 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=Occludin+oligomeric+assemblies+at+tight+junctions+of+the+blood-brain+barrier+are+altered+by+hypoxia+and+reoxygenation+stress.">Occludin oligomeric assemblies at tight junctions of the blood-brain barrier are altered by hypoxia and reoxygenation stress.</a> J Neurochem. 110 (1), 58-71 (2009).</li><li>Lochhead, J. 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=Oxidative+stress+increases+blood-brain+barrier+permeability+and+induces+alterations+in+occludin+during+hypoxia-reoxygenation.">Oxidative stress increases blood-brain barrier permeability and induces alterations in occludin during hypoxia-reoxygenation.</a> J Cereb Blood Flow Metab. 30 (9), 1625-1636 (2010).</li><li>Lucke-Wold, B. 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=Bryostatin-1+Restores+Blood+Brain+Barrier+Integrity+following+Blast-Induced+Traumatic+Brain+Injury.">Bryostatin-1 Restores Blood Brain Barrier Integrity following Blast-Induced Traumatic Brain Injury.</a> Mol Neurobiol. 52 (3), 1119-1134 (2015).</li><li>Campos, C. R., Ocheltree, S. M., Hom, S., Egleton, R. D., Davis, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nociceptive+inhibition+prevents+inflammatory+pain+induced+changes+in+the+blood-brain+barrier.">Nociceptive inhibition prevents inflammatory pain induced changes in the blood-brain barrier.</a> Brain Res. , 6-13 (2008).</li><li>Ronaldson, P. T., Demarco, K. M., Sanchez-Covarrubias, L., Solinsky, C. M., Davis, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transforming+growth+factor-beta+signaling+alters+substrate+permeability+and+tight+junction+protein+expression+at+the+blood-brain+barrier+during+inflammatory+pain.">Transforming growth factor-beta signaling alters substrate permeability and tight junction protein expression at the blood-brain barrier during inflammatory pain.</a> J Cereb Blood Flow Metab. 29 (6), 1084-1098 (2009).</li><li>Seelbach, M. J., Brooks, T. A., Egleton, R. D., Davis, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peripheral+inflammatory+hyperalgesia+modulates+morphine+delivery+to+the+brain:+a+role+for+P-glycoprotein.">Peripheral inflammatory hyperalgesia modulates morphine delivery to the brain: a role for P-glycoprotein.</a> J Neurochem. 102 (5), 1677-1690 (2007).</li><li>Ronaldson, P. T., Finch, J. D., Demarco, K. M., Quigley, C. E., Davis, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammatory+pain+signals+an+increase+in+functional+expression+of+organic+anion+transporting+polypeptide+1a4+at+the+blood-brain+barrier.">Inflammatory pain signals an increase in functional expression of organic anion transporting polypeptide 1a4 at the blood-brain barrier.</a> J Pharmacol Exp Ther. 336 (3), 827-839 (2011).</li><li>Pop, V., 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=Early+brain+injury+alters+the+blood-brain+barrier+phenotype+in+parallel+with+beta-amyloid+and+cognitive+changes+in+adulthood.">Early brain injury alters the blood-brain barrier phenotype in parallel with beta-amyloid and cognitive changes in adulthood.</a> J Cereb Blood Flow Metab. 33 (2), 205-214 (2013).</li><li>Thompson, B. 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=Hypoxia/reoxygenation+stress+signals+an+increase+in+organic+anion+transporting+polypeptide+1a4+(Oatp1a4)+at+the+blood-brain+barrier:+relevance+to+CNS+drug+delivery.">Hypoxia/reoxygenation stress signals an increase in organic anion transporting polypeptide 1a4 (Oatp1a4) at the blood-brain barrier: relevance to CNS drug delivery.</a> J Cereb Blood Flow Metab. 34 (4), 699-707 (2014).</li><li>Tome, M. E., 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=P-glycoprotein+traffics+from+the+nucleus+to+the+plasma+membrane+in+rat+brain+endothelium+during+inflammatory+pain.">P-glycoprotein traffics from the nucleus to the plasma membrane in rat brain endothelium during inflammatory pain.</a> J Cereb Blood Flow Metab. 36 (11), 1913-1928 (2016).</li><li>Slosky, L. 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=Acetaminophen+modulates+P-glycoprotein+functional+expression+at+the+blood-brain+barrier+by+a+constitutive+androstane+receptor-dependent+mechanism.">Acetaminophen modulates P-glycoprotein functional expression at the blood-brain barrier by a constitutive androstane receptor-dependent mechanism.</a> Mol Pharmacol. 84 (5), 774-786 (2013).</li><li>Artus, 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+Wnt/planar+cell+polarity+signaling+pathway+contributes+to+the+integrity+of+tight+junctions+in+brain+endothelial+cells.">The Wnt/planar cell polarity signaling pathway contributes to the integrity of tight junctions in brain endothelial cells.</a> J Cereb Blood Flow Metab. 34 (3), 433-440 (2014).</li><li>Yu, 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=Long-term+exposure+to+ethanol+downregulates+tight+junction+proteins+through+the+protein+kinase+Calpha+signaling+pathway+in+human+cerebral+microvascular+endothelial+cells.">Long-term exposure to ethanol downregulates tight junction proteins through the protein kinase Calpha signaling pathway in human cerebral microvascular endothelial cells.</a> Exp Ther Med. 14 (5), 4789-4796 (2017).</li><li>Abdullahi, W., Brzica, H., Ibbotson, K., Davis, T. P., Ronaldson, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bone+morphogenetic+protein-9+increases+the+functional+expression+of+organic+anion+transporting+polypeptide+1a4+at+the+blood-brain+barrier+via+the+activin+receptor-like+kinase-1+receptor.">Bone morphogenetic protein-9 increases the functional expression of organic anion transporting polypeptide 1a4 at the blood-brain barrier via the activin receptor-like kinase-1 receptor.</a> J Cereb Blood Flow Metab. 37 (7), 2340-2345 (2017).</li><li>Mesev, E. V., Miller, D. S., Cannon, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ceramide+1-Phosphate+Increases+P-Glycoprotein+Transport+Activity+at+the+Blood-Brain+Barrier+via+Prostaglandin+E2+Signaling.">Ceramide 1-Phosphate Increases P-Glycoprotein Transport Activity at the Blood-Brain Barrier via Prostaglandin E2 Signaling.</a> Mol Pharmacol. 91 (4), 373-382 (2017).</li><li>Betz, A. L., Csejtey, J., Goldstein, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hexose+transport+and+phosphorylation+by+capillaries+isolated+from+rat+brain.">Hexose transport and phosphorylation by capillaries isolated from rat brain.</a> Am J Physiol. 236 (1), C96-C102 (1979).</li><li>Yousif, S., Marie-Claire, C., Roux, F., Scherrmann, J. M., Decleves, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+drug+transporters+at+the+blood-brain+barrier+using+an+optimized+isolated+rat+brain+microvessel+strategy.">Expression of drug transporters at the blood-brain barrier using an optimized isolated rat brain microvessel strategy.</a> Brain Res. 1134 (1), 1-11 (2007).</li><li>McCaffrey, 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=Tight+junctions+contain+oligomeric+protein+assembly+critical+for+maintaining+blood-brain+barrier+integrity+in+vivo.">Tight junctions contain oligomeric protein assembly critical for maintaining blood-brain barrier integrity in vivo.</a> J Neurochem. 103 (6), 2540-2555 (2007).</li><li>Brzica, 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=The+liver+and+kidney+expression+of+sulfate+anion+transporter+sat-1+in+rats+exhibits+male-dominant+gender+differences.">The liver and kidney expression of sulfate anion transporter sat-1 in rats exhibits male-dominant gender differences.</a> Pflugers Arch. 457 (6), 1381-1392 (2009).</li><li>Ronaldson, P. T., Bendayan, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HIV-1+viral+envelope+glycoprotein+gp120+produces+oxidative+stress+and+regulates+the+functional+expression+of+multidrug+resistance+protein-1+(Mrp1)+in+glial+cells.">HIV-1 viral envelope glycoprotein gp120 produces oxidative stress and regulates the functional expression of multidrug resistance protein-1 (Mrp1) in glial cells.</a> J Neurochem. 106 (3), 1298-1313 (2008).</li><li>Pustylnikov, S., Sagar, D., Jain, P., Khan, Z. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+the+C-type+lectins-mediated+host-pathogen+interactions+with+dextran.">Targeting the C-type lectins-mediated host-pathogen interactions with dextran.</a> J Pharm Pharm Sci. 17 (3), 371-392 (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>Abdullahi, W., Davis, T. P., Ronaldson, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+Expression+of+P-glycoprotein+and+Organic+Anion+Transporting+Polypeptides+at+the+Blood-Brain+Barrier:+Understanding+Transport+Mechanisms+for+Improved+CNS+Drug+Delivery?.">Functional Expression of P-glycoprotein and Organic Anion Transporting Polypeptides at the Blood-Brain Barrier: Understanding Transport Mechanisms for Improved CNS Drug Delivery?.</a> AAPS J. 19 (4), 931-939 (2017).</li></ol>

The authors have nothing to disclose.

In this article, a simple and effective method of preparing membrane protein samples from microvessels freshly isolated from rat brain tissue is described. Several approaches for isolation of rat brain microvessels and/or generation of membrane preparations from isolated microvasculature have been reported in the literature13,20,21,22,24. Although the microves...

The blood-brain barrier (BBB) exists at the interface between the central nervous system (CNS) and the systemic circulation and plays an essential role in the maintenance of brain homeostasis. Specifically, the BBB functions to precisely control solute concentrations in brain extracellular fluid and to efficiently supply those nutrients that are required by brain tissue to fulfill the considerable metabolic demands of the CNS1. These roles imply that the BBB, which exists primarily at the level of the microvascular endothelial cell, must possess discrete mechanisms that enable some substances to access brain parenchyma while ensuring that potentially harmful xenobiotics cannot accumulate. Indeed, brain microvascular endothelial cells are not fenestrated and exhibit limited pinocytosis, which ensures a lack of non-selective permeability2. Additionally, brain microvessel endothelial cells express tight junction and adherens junction proteins that act to form a physical &#34;seal&#34; between adjacent endothelial cells and greatly restrict paracellular diffusion of blood-borne substances into brain parenchyma. Indeed, selective permeability of endogenous and exogenous substances requires functional expression of uptake and efflux transporters3. Overall, tight junctions, adherens junctions, and transporters work in concert to maintain the unique barrier properties of the BBB.
The BBB is a dynamic barrier that responds to physiological, pathophysiological, and pharmacological stimuli. For example, hypoxia/reoxygenation stress has been shown to modulate expression of critical tight junction proteins (i.e., occludin, zonulae occluden-1 (ZO-1)), which is associated with increased paracellular permeability to vascular markers such as sucrose4,5,6. Similar observations have been made at the BBB in the setting of traumatic brain injury7 and peripheral inflammatory pain8,9. These same diseases can also modulate transport mechanisms at the BBB10,11,12,13,14. Indeed, hypoxia/reoxygenation injury enhances functional expression of organic anion transporting polypeptide 1a4 (Oatp1a4) at the BBB, which can lead to significant increases in the blood-to-brain transport of specific Oatp transport substrates such as taurocholate and atorvastatin13. BBB properties can also be altered by pharmacotherapy itself, a mechanism that can form a basis for both profound changes in the drug effectiveness in the brain and for drug-drug interactions. For example, acetaminophen targets nuclear receptor signaling mechanisms in the brain microvascular endothelial cells, increases functional expression of the critical efflux transporter P-glycoprotein (P-gp), and modifies time-dependent analgesia conferred by morphine, an opioid analgesic drug and established P-gp transport substrate15. A thorough understanding of BBB changes, that can be induced by diseases or by drugs, also requires identification and characterization of specific regulatory mechanisms that control these modifications. Indeed, discrete signaling pathways have been identified in brain microvascular endothelial cells that control the molecular expression of tight junction proteins16,17 and transporters15,18,19. Taken together, these observations indicate that complex molecular pathways are involved in the regulation of BBB tight junctions and transporters in both health and disease.
A significant challenge in the study of the BBB is the absolute requirement of a simple and effective method for isolation of microvessels from brain tissue derived from experimental animals and subsequent preparation of membrane samples. These samples must be prepared so that they are both enriched in brain microvascular endothelial cells and limited in presence of other cell types. Over the past several years, multiple methodologies for isolation of microvasculature from rodent brain have been reported in the scientific literature13,20,21,22. This article describes a simple, robust, and reproducible method for isolation of microvessels from rat brain and for preparation of endothelial membrane-enriched samples that can be used for the analysis of protein expression. An advantage of this microvessel isolation protocol is the ability to obtain sample preparations of high quality and with sufficient protein yield from an individual experimental animal. This enables the consideration of inter-animal variability in protein expression. Such an advance in this protocol has greatly improved the robustness of BBB studies because over-estimation (or under-estimation) of the true magnitude of protein changes at the BBB can now be avoided. Additionally, the inclusion of multiple centrifugation steps with dextran enables improved enrichment of microvessels in experimental samples while facilitating removal of unwanted cellular constituents such as neurons.

<table>
	<tbody>
		<tr>
			<td>Protease Inhibitor Cocktail</td>
			<td>Sigma-Aldrich</td>
			<td>#P8340</td>
			<td>Component of brain microvessel buffer</td>
		</tr>
		<tr>
			<td>D-mannitol</td>
			<td>Sigma-Aldrich</td>
			<td>#M4125</td>
			<td>Component of brain microvessel buffer</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma-Aldrich</td>
			<td>#E3889</td>
			<td>Component of brain microvessel buffer</td>
		</tr>
		<tr>
			<td>Trizma Base</td>
			<td>Sigma-Aldrich</td>
			<td>#T1503</td>
			<td>Component of brain microvessel buffer</td>
		</tr>
		<tr>
			<td>Dextran (MW 75,000)</td>
			<td>Spectrum Chemical Mftg Corp</td>
			<td>#DE125</td>
			<td>Dextran used in centrifugation steps to separate microvessels from brain parenchyma</td>
		</tr>
		<tr>
			<td>Zetamine</td>
			<td>MWI Animal Health</td>
			<td>#501072</td>
			<td>General anesthetic</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Western Medical Supply</td>
			<td>#5530</td>
			<td>General anesthetic</td>
		</tr>
		<tr>
			<td>0.9% saline solution</td>
			<td>Western Medical Supply</td>
			<td>N/A</td>
			<td>General anesthetic diluent</td>
		</tr>
		<tr>
			<td>Filter Paper (12.5 cm diameter)</td>
			<td>VWR</td>
			<td>#28320-100</td>
			<td>Used for removal of meninges from brain tissue</td>
		</tr>
		<tr>
			<td>Centrifuge Tubes</td>
			<td>Sarstedt</td>
			<td>#60.540.386</td>
			<td>Disposable tubes used for dextran centrifugation steps</td>
		</tr>
		<tr>
			<td>Pierce&#8482; Coomassie Plus (Bradford) Assay</td>
			<td>ThermoFisher Scientific</td>
			<td>#23236</td>
			<td>Measurement of protein concentration in membrane preparations</td>
		</tr>
		<tr>
			<td>Wheaton Overhead Power Homogenizer</td>
			<td>DWK Life Sciences</td>
			<td>#903475</td>
			<td>Required for homogenization of samples</td>
		</tr>
		<tr>
			<td>10.0ml glass mortar and pestle tissue grinder</td>
			<td>DWK Life Sciences</td>
			<td>#358039</td>
			<td>Required for homogenization of samples</td>
		</tr>
		<tr>
			<td>Hydrochloric Acid</td>
			<td>Sigma-Aldrich</td>
			<td>#H1758</td>
			<td>Required for pH adjustment of buffers</td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>ThermoFisher Scientific</td>
			<td>#23210</td>
			<td>Protein standard for Bradford Assay</td>
		</tr>
		<tr>
			<td>Standard Forceps</td>
			<td>Fine Science Tools</td>
			<td>#91100-12</td>
			<td>Used for dissection of brain tissue</td>
		</tr>
		<tr>
			<td>Friedman-Pearson Rongeurs</td>
			<td>Fine Science Tools</td>
			<td>#16020-14</td>
			<td>Used for opening skull to isolate brain</td>
		</tr>
		<tr>
			<td>50 ml conical centrifuge tubes</td>
			<td>ThermoFisher Scientific</td>
			<td>#352070</td>
			<td>Used for collection of brain tissue following isolation</td>
		</tr>
		<tr>
			<td>Glass Pasteur Pipets</td>
			<td>ThermoFisher Scientific</td>
			<td>#13-678-20C</td>
			<td>Used for aspiration of cellular debris following dextran spins</td>
		</tr>
		<tr>
			<td>Ethanol, anhydrous</td>
			<td>Sigma-Aldrich</td>
			<td>#459836</td>
			<td>Used for cleaning tissue grinder; diluted to 70% with distilled water</td>
		</tr>
		<tr>
			<td>Ultracentrifuge tubes</td>
			<td>Beckman-Coulter</td>
			<td>#41121703</td>
			<td>Used for ultracentrifugation of samples</td>
		</tr>
	</tbody>
</table>

a simple and reproducible method to prepare membrane samples from freshly isolated rat brain microvessels

The blood-brain barrier (BBB) is a dynamic barrier tissue that responds to various pathophysiological and pharmacological stimuli. Such changes resulting from these stimuli can greatly modulate drug delivery to the brain and, by extension, cause considerable challenges in the treatment of central nervous system (CNS) diseases. Many BBB changes that affect pharmacotherapy, involve proteins that are localized and expressed at the level of endothelial cells. Indeed, such knowledge on BBB physiology in health and disease has sparked considerable interest in the study of these membrane proteins. From a basic science research standpoint, this implies a requirement for a simple but robust and reproducible method for isolation of microvessels from brain tissue harvested from experimental animals. In order to prepare membrane samples from freshly isolated microvessels, it is essential that sample preparations be enriched in endothelial cells but limited in the presence of other cell types of the neurovascular unit (i.e., astrocytes, microglia, neurons, pericytes). An added benefit is the ability to prepare samples from individual animals in order to capture the true variability of protein expression in an experimental population. In this manuscript, details regarding a method that is utilized for isolation of rat brain microvessels and preparation of membrane samples are provided. Microvessel enrichment, from samples derived, is achieved by using four centrifugation steps where dextran is included in the sample buffer. This protocol can easily be adapted by other laboratories for their own specific applications. Samples generated from this protocol have been shown to yield robust experimental data from protein analysis experiments that can greatly aid the understanding of BBB responses to physiological, pathophysiological, and pharmacological stimuli.

The experimental flow for isolation of rat brain microvessels and for the preparation of microvessel membrane samples is shown in Figure 1. Using the procedure presented here, successful isolation of intact microvessels from rat brain is demonstrated (Figure 2A). These vessels were obtained following completion of centrifugation with dextran and immediately prior to commencing ultracentrifugation to prepare membrane samples (i.e....

Watch this Scientific Journal Video about A Simple and Reproducible Method to Prepare Membrane Samples from Freshly Isolated Rat Brain Microvessels at JoVE.com

A Simple and Reproducible Method to Prepare Membrane Samples from Freshly Isolated Rat Brain Microvessels

Here, a method for isolation of rat brain microvessels and for the preparation of membrane samples is described. This protocol has the clear advantage of producing enriched microvessel samples with acceptable protein yield from individual animals. Samples can then be used for robust protein analyses at the brain microvascular endothelium.

The blood-brain barrier (BBB) is a dynamic barrier tissue that responds to various pathophysiological and pharmacological stimuli. Such changes resulting ...

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Research

JoVE Journal

Neuroscience

10.0K Views.  University of Arizona, Tucson. Here, a method for isolation of rat brain microvessels and for the preparation of membrane samples is described. This protocol has the clear advantage of producing enriched microvessel samples with acceptable protein yield from individual animals. Samples can then be used for robust protein analyses at the brain microvascular endothelium.

Video: A Simple and Reproducible Method to Prepare Membrane Samples from Freshly Isolated Rat Brain Microvessels

The Vermicelli and Capellini Handling Tests: Simple quantitative measures of dexterous forepaw function in rats and mice

Previous characterizations of rodent eating behavior have revealed that they use coordinated forepaw movements to manipulate food pieces. We have extended upon this work to develop a simple quantitative measure of forepaw dexterity that is sensitive to lateralized impairments and age-dependent changes. Rodents learn skillful forepaw and digit movements to manage thin pasta pieces, which they eagerly consume. We have previously described methods for quantifying vermicelli handling in rats and showed that the measures are very sensitive to forelimb impairments resulting from unilateral ischemic lesions, middle cerebral artery occlusions and unilateral striatal dopamine depletion [Allred, R.P., Adkins, D.L., Woodlee, M.T., Husbands, L.C., Maldonado M.A., Kane, J.R., Schallert, T. &amp; Jones, T.A. The Vermicelli Handling Test: a simple quantitative measure of dexterous forepaw function in rats. J. Neurosci. Methods 170, 229-244 (2008)]. Here we present a more detailed protocol for this test in rats and compare it with a newly developed version for mice, the Capellini Handling Test. Rats and mice are videotaped while handling short lengths of uncooked vermicelli or capellini pasta, respectively, with a camera positioned to optimize the view of paw movements. Slow motion video playback allows for the identification of forepaw adjustments, defined as any distinct removal and replacement of the paw, or of any number of digits, on the pasta piece after eating commences. Forepaw adjustments per piece are averaged over trials per each testing session. Repeated testing permits sensitive quantitative analysis of changes in forepaw dexterity over time. Protocols for pre-testing habituation and handling practice, as well as procedures for characterizing atypical handling patterns, are described. Because rats and mice perform the pasta handling tests slightly differently, species-specific differences in administration and scoring of these tests are highlighted. All animal use was in accordance with protocols approved by the University of Texas at Austin Animal Care and Use Committee.

The Vermicelli and Capellini Handling Tests of forepaw dexterity take advantage of the natural inclination of rodents to manipulate food items using skillful forepaw and digit movements. Animals are videotaped while handling short strands of uncooked dry pasta. Slow motion video playback allows for the quantification of forepaw adjustments.

Previous characterizations of rodent eating behavior have revealed that they use coordinated forepaw movements to manipulate food pieces. We have extended ...

Gene Delivery to Postnatal Rat Brain by Non-ventricular Plasmid Injection and Electroporation

Creation of transgenic animals is a standard approach in studying functions of a gene of interest in vivo. However, many knockout or transgenic animals are not viable in those cases where the modified gene is expressed or deleted in the whole organism. Moreover, a variety of compensatory mechanisms often make it difficult to interpret the results. The compensatory effects can be alleviated by either timing the gene expression or limiting the amount of transfected cells.
The method of postnatal non-ventricular microinjection and in vivo electroporation allows targeted delivery of genes, siRNA or dye molecules directly to a small region of interest in the newborn rodent brain. In contrast to conventional ventricular injection technique, this method allows transfection of non-migratory cell types. Animals transfected by means of the method described here can be used, for example, for two-photon in vivo imaging or in electrophysiological experiments on acute brain slices.

This protocol describes a non-viral method of delivery of genetic constructs to a certain area of living rodent brain. The method consists of plasmid preparation, micropipette fabrication, neonatal rat pup surgery, microinjection of the construct, and in vivo electroporation.

Creation of transgenic animals is a standard approach in studying functions of a gene of interest in vivo. However, many knockout or transgenic animals ...

Quantitative Analysis of Synaptic Vesicle Pool Replenishment in Cultured Cerebellar Granule Neurons using FM Dyes

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis. Retrieved SVs are then refilled with neurotransmitter and rejoin the recycling pool, defined as SVs that are available for exocytosis1,2. The recycling pool can generally be subdivided into two distinct pools - the readily releasable pool (RRP) and the reserve pool (RP). As their names imply, the RRP consists of SVs that are immediately available for fusion while RP SVs are released only during intense stimulation1,2. It is important to have a reliable assay that reports the differential replenishment of these SV pools in order to understand 1) how SVs traffic after different modes of endocytosis (such as clathrin-dependent endocytosis and activity-dependent bulk endocytosis) and 2) the mechanisms controlling the mobilisation of both the RRP and RP in response to different stimuli.
FM dyes are routinely employed to quantitatively report SV turnover in central nerve terminals3-8. They have a hydrophobic hydrocarbon tail that allows reversible partitioning in the lipid bilayer, and a hydrophilic head group that blocks passage across membranes. The dyes have little fluorescence in aqueous solution, but their quantum yield increases dramatically when partitioned in membrane9. Thus FM dyes are ideal fluorescent probes for tracking actively recycling SVs. The standard protocol for use of FM dye is as follows. First they are applied to neurons and are taken up during endocytosis (Figure 1). After non-internalised dye is washed away from the plasma membrane, recycled SVs redistribute within the recycling pool. These SVs are then depleted using unloading stimuli (Figure 1). Since FM dye labelling of SVs is quantal10, the resulting fluorescence drop is proportional to the amount of vesicles released. Thus, the recycling and fusion of SVs generated from the previous round of endocytosis can be reliably quantified.
Here, we present a protocol that has been modified to obtain two additional elements of information. Firstly, sequential unloading stimuli are used to differentially unload the RRP and the RP, to allow quantification of the replenishment of specific SV pools. Secondly, each nerve terminal undergoes the protocol twice. Thus, the response of the same nerve terminal at S1 can be compared against the presence of a test substance at phase S2 (Figure 2), providing an internal control. This is important, since the extent of SV recycling across different nerve terminals is highly variable11.
Any adherent primary neuronal cultures may be used for this protocol, however the plating density, solutions and stimulation conditions are optimised for cerebellar granule neurons (CGNs)12,13.

A live fluorescence imaging technique to quantify the replenishment and mobilisation of specific synaptic vesicle (SV) pools in central nerve terminals is described. Two rounds of SV recycling are monitored in the same nerve terminals providing an internal control.

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis.  Retrieved SVs are then refilled with ...

A Visual Description of the Dissection of the Cerebral Surface Vasculature and Associated Meninges and the Choroid Plexus from Rat Brain

This video presentation was created to show a method of harvesting the two most important highly vascular structures, not residing within the brain proper, that support forebrain function. They are the cerebral surface (superficial) vasculature along with associated meninges (MAV) and the choroid plexus which are necessary for cerebral blood flow and cerebrospinal fluid (CSF) homeostasis. The tissue harvested is suitable for biochemical and physiological analysis, and the MAV has been shown to be sensitive to damage produced by amphetamine and hyperthermia 1,2. As well, the major and minor cerebral vasculatures harvested in MAV are of potentially high interest when investigating concussive types of head trauma. The MAV dissected in this presentation consists of the pial and some of the arachnoid membrane (less dura) of the meninges and the major and minor cerebral surface vasculature. The choroid plexus dissected is the structure that resides in the lateral ventricles as described by Oldfield and McKinley3,4,5,6. The methods used for harvesting these two tissues also facilitate the harvesting of regional cortical tissue devoid of meninges and larger cerebral surface vasculature, and is compatible with harvesting other brain tissues such as striatum, hypothalamus, hippocampus, etc. The dissection of the two tissues takes from 5 to 10 min total. The gene expression levels for the dissected MAV and choroid plexus, as shown and described in this presentation can be found at GSE23093 (MAV) and GSE29733 (choroid plexus) at the NCBI GEO repository. This data has been, and is being, used to help further understand the functioning of the MAV and choroid plexus and how neurotoxic events such as severe hyperthermia and AMPH adversely affect their function.

This video presentation shows a method of harvesting the two most important highly vascular structures that support forebrain function. They are the cerebral surface (superficial) vasculature along with associated meninges (MAV) and the choroid plexus which are necessary for cerebral blood flow and cerebrospinal fluid (CSF) homeostasis.

This video presentation was created to show a method of harvesting the two most important highly vascular structures, not residing within the brain ...

Using Fluorescence Activated Cell Sorting to Examine Cell-Type-Specific Gene Expression in Rat Brain Tissue

The brain is comprised of four primary cell types including neurons, astrocytes, microglia and oligodendrocytes. Though they are not the most abundant cell type in the brain, neurons are the most widely studied of these cell types given their direct role in impacting behaviors. Other cell types in the brain also impact neuronal function and behavior via the signaling molecules they produce. Neuroscientists must understand the interactions between the cell types in the brain to better understand how these interactions impact neural function and disease. To date, the most common method of analyzing protein or gene expression utilizes the homogenization of whole tissue samples, usually with blood, and without regard for cell type. This approach is an informative approach for examining general changes in gene or protein expression that may influence neural function and behavior; however, this method of analysis does not lend itself to a greater understanding of cell-type-specific gene expression and the effect of cell-to-cell communication on neural function. Analysis of behavioral epigenetics has been an area of growing focus which examines how modifications of the deoxyribonucleic acid (DNA) structure impact long-term gene expression and behavior; however, this information may only be relevant if analyzed in a cell-type-specific manner given the differential lineage and thus epigenetic markers that may be present on certain genes of individual neural cell types. The Fluorescence Activated Cell Sorting (FACS) technique described below provides a simple and effective way to isolate individual neural cells for the subsequent analysis of gene expression, protein expression, or epigenetic modifications of DNA. This technique can also be modified to isolate more specific neural cell types in the brain for subsequent cell-type-specific analysis.

The goal of this protocol is to use the fluorescence activated cell sorting (FACS) technique to sort specific types of neural cells for subsequent analysis of cell-type-specific gene expression, epigenetic markers, and or protein expression.

The brain is comprised of four primary cell types including neurons, astrocytes, microglia and oligodendrocytes. Though they are not the most abundant ...

A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity.
Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 &#176;C to 5 &#176;C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above.
This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

The Cold Plantar Assay (CPA) measures cold responsiveness between 30 &#176;C and 5 &#176;C, and can also measure cold adaptation. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life.  The cold ...

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies using Drosophila have contributed important breakthroughs in understanding neurological processes. Thus, with the goal of understanding the cellular and molecular basis of TBI pathologies in humans, we developed the High Impact Trauma (HIT) device to inflict closed head TBI in flies. Flies subjected to the HIT device display phenotypes consistent with human TBI such as temporary incapacitation and progressive neurodegeneration. The HIT device uses a spring-based mechanism to propel flies against the wall of a vial, causing mechanical damage to the fly brain. The device is inexpensive and easy to construct, its operation is simple and rapid, and it produces reproducible results. Consequently, the HIT device can be combined with existing experimental tools and techniques for flies to address fundamental questions about TBI that can lead to the development of diagnostics and treatments for TBI. In particular, the HIT device can be used to perform large-scale genetic screens to understand the genetic basis of TBI pathologies.

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Here we describe a method to inflict closed head traumatic brain injury (TBI) in Drosophila. This method provides a gateway to investigate the cellular and molecular mechanisms that underlie TBI pathologies using the vast array of experimental tools and techniques available for flies.

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies ...

A Simple Alternative to Stereotactic Injection for Brain Specific Knockdown of miRNA

MicroRNAs (miRNAs) are key regulators of gene expression. In the brain, vital processes like neurodevelopment and neuronal functions depend on the correct expression of microRNAs. Perturbation of microRNAs in the brain can be used to model neurodegenerative diseases by modulating neuronal cell death. Currently, stereotactic injection is used to deliver miRNA knockdown agents to specific location in the brain. Here, we discuss strategies to design antagomirs against miRNA with locked nucleotide modifications (LNA). Subsequently describe a method for brain specific delivery of antagomirs, uniformly across different regions of the brain. This method is simple and widely applicable since it overcomes the surgery, associated injury and limitation of local delivery in stereotactic injections. We prepared a complex of neurotropic, cell-penetrating peptide Rabies Virus Glycoprotein (RVG) with antagomir against miRNA-29 and injected through tail vein, to specifically deliver in the brain. The antagomir design incorporated features that allow specific targeting of the miRNA and formation of non-covalent complexes with the peptide. The knock-down of the miRNA in neuronal cells, resulted in apoptotic cell death and associated behavioural defects. Thus, the method can be used for acute models of neuro-degeneration through the perturbation of miRNAs.

MicroRNAs play crucial roles in the brain and are potential targets for modeling neuro-degeneration. However, perturbing miRNA levels is challenging due to the short length of miRNA and inaccessibility of the brain tissue. This video presents a method for antagomir design and brain specific delivery using a neuropeptide in mice.

MicroRNAs (miRNAs) are key regulators of gene expression.  In the brain, vital processes like neurodevelopment and neuronal functions depend on the ...

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We demonstrate a simple way to tap into the fly reward system, modify experiences related to natural reward, and use voluntary ethanol consumption as a measure for changes in reward states. The approach serves as a relevant tool to study the neurons and genes that play a role in experience-mediated changes of internal state. The protocol is composed of two discrete parts: exposing the flies to rewarding and nonrewarding experiences, and assaying voluntary ethanol consumption as a measure of the motivation to obtain a drug reward. The two parts can be used independently to induce the modulation of experience as an initial step for further downstream assays or as an independent two-choice feeding assay, respectively. The protocol does not require a complicated setup and can therefore be applied in any laboratory with basic fly culture tools.

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for inducing rewarding and nonrewarding experiences in fruit flies (Drosophila melanogaster) using voluntary ethanol consumption as a measure for changes in reward states.

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We ...

Simple Generation of a High Yield Culture of Induced Neurons from Human Adult Skin Fibroblasts

Induced neurons (iNs), the product of somatic cells directly converted to neurons, are a way to obtain patient-derived neurons from tissue that is easily accessible. Through this route, mature neurons can be obtained in a matter of a few weeks. Here, we describe a straightforward and rapid one-step protocol to obtain iNs from dermal fibroblasts obtained through biopsy samples from adult human donors. We explain each step of the process, including the maintenance of the dermal fibroblasts, the freezing procedure to build a stock of the cell line, seeding of the cells for reprogramming, as well as the culture conditions during the conversion process. In addition, we describe the preparation of glass coverslips for electrophysiological recordings, long-term coating conditions, and fluorescence activated cell sorting (FACS). We also illustrate examples of the results to be expected. The protocol described here is easy to perform and can be applied to human fibroblasts derived from human skin biopsies from patients with various different diagnoses and ages. This protocol generates a sufficient amount of iNs which can be used for a wide array of biomedical applications, including disease modeling, drug screening, and target validation.

Direct neuronal reprogramming generates neurons that maintain the age of the starting somatic cell. Here, we describe a single vector-based method to generate induced neurons from dermal fibroblasts obtained from adult human donors.

Induced neurons (iNs), the product of somatic cells directly converted to neurons, are a way to obtain patient-derived neurons from tissue that is easily ...