This work was supported by &#34;Fondazione Neuromed&#34; and funded by the Italian Ministry of Health &#34;Ricerca Corrente&#34; to V.M.

All procedures on animals were approved by the IRCCS Neuromed Animal Care Review Board and by &#34;Istituto Superiore di Sanit&#224;&#34; (permit number: 1163/2015- PR) and were in accordance with the guidelines of the EU Directive 2010/63/EU for animal experiments.
1. Preparation of FITC-albumin Solution to be Injected into Jugular Vein
NOTE: All experiments were carried out in manifest (11-week old) HD R6/2 mice and in age and gender-matched wild-type (WT) control littermates.
<ol>
	<li>Dissolve FITC-albumin powder (see Table of Materials) in phosphate buffered saline (PBS) at 10 mg/ml. 
	NOTE: For optimal results, this should be prepared fresh for each labelling reaction.</li>
</ol>
2. Preparation of Equipment to Be Used During Surgery
<ol>
	<li>Lay out the previously autoclaved surgical instruments (see Table of Materials).</li>
	<li>Clean the surgical bench with alcohol (70% ethanol solution). Prepare the surgical area (45 cm x 45 cm) with a surgical sterile disposable towel drape and set up the operating stereomicroscope.</li>
</ol>
3. Surgical Procedure for FITC-albumin Infusion into the Jugular Vein
<ol>
	<li>Record mouse body weight for anesthesia.</li>
	<li>Anesthetize mouse with an intraperitoneal injection (i.p) of an appropriate dose of Ketamine (100 mg/kg) - xylazine (10 mg/kg) solution.</li>
	<li>Monitor animal sedation by gentle toe pinch withdraw reflex as demonstrated in Walantus et al.11,12.</li>
	<li>Place the anesthetized mouse in a face-up supine position and fix the four legs and the tail on the surgical workbench with adhesive tape.</li>
	<li>After the mouse is secured, carefully shave the appropriate surgical margin on the neck with an electric razor (see Table of Materials) and disinfect it with povidone-iodine solution and 70% ethanol.</li>
	<li>Dry the exposed shaved surface with cotton swabs.</li>
	<li>Gently pull up the shaved skin and make a 1.5 cm long longitudinal incision, by scalpel, in the midclavicular line starting midway on the thorax and extending to just below the neck.</li>
	<li>Carefully stretch apart connective tissue with forceps under microscopic observation (5X magnification) to expose the external jugular vein.</li>
	<li>Ensure a sufficient space on the right and on the left of the jugular vein to facilitate the insertion of the 30&#189; G needle for the infusion of the FITC-albumin solution.</li>
	<li>Inject the animal intravenously (right jugular vein) slowly (over 3 min) with 100 &#181;L of 10 mL/kg FITC-albumin by using the 30&#189; G needle.</li>
	<li>After 15 minutes, euthanize the mouse by decapitation, rapidly remove the brain from the skull as previously described13, and immerse it for 15 min in at least 10x the volume of the brain itself of pre-chilled isopentane.</li>
	<li>Move the isopentane frozen brain into a pre-chilled tube and store it into a -80 &#176;C freezer until histological sectioning.</li>
</ol>
4. Histological Sectioning of Brain Infused with FITC-albumin
<ol>
	<li>Embed frozen brain in optimal cutting temperature (OCT) compound (see Table of Materials) prior to cryostat sectioning.</li>
	<li>Serially cut the brain into 20 &#181;m thick sections, with a cryostat (see Table of Materials), and mount them onto microscope glass slides.</li>
	<li>Perform the FITC-Albumin/laminin co-staining by using a specific anti-laminin antibody (see Table of Materials) as previously described6.
	<ol>
		<li>Briefly, incubate sections with the primary antibody anti-laminin (pAb 1:1000) over night and proceed with appropriate secondary antibody conjugated to Cy3.</li>
		<li>Coverslip slides with mounting medium containing 4&#39;,6-diamidino-2-phenylindole (DAPI) (absorption peak = 360 nm; emission peak = 460 nm (see Table of Materials).</li>
		<li>Leave the slide to dry overnight at 4 &#176;C in the dark.</li>
		<li>Observe the fluorescence staining under a fluorescence microscope (see Table of Materials) at 20X magnification equipped with both FITC (absorption peak = 495 nm; emission peak = 525 nm) and Cy3 filters (absorption peak = 550 nm; emission peak = 570 nm).
		<ol>
			<li>To view the samples immediately after the staining, secure the coverslip at the corners using nail polish and examine them under the microscope as above (4.3.3).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
5. Setting Up the Fluorescence Microscope and Acquisition of Colour Images
<ol>
	<li>Set up the fluorescence microscope as follows.
	<ol>
		<li>Turn on the fluorescence lamp about 10 minutes before use. Turn on the microscope, the connected computer, and the digital camera. Run the image analysis software (see Table of Materials).</li>
		<li>Use the appropriate objective for optimal signal collection and spatial resolution, and select appropriate filters.</li>
	</ol>
	</li>
	<li>Acquisition of Colour Images
	<ol>
		<li>Select the [live] command on the image analysis software (see Table of Materials) and set up the optimal illumination parameters for each filter.</li>
		<li>Select the [freeze] command to take the single channel colour image and add the scale bar (&#39;Edit&#62;Burn Scale&#39;)</li>
		<li>Save each image in the &#39;.tiff&#39; format.</li>
		<li>Merge channels into a single image by selecting &#39;File&#62;Merge channel&#39; and save it in the</li>
		<li>tiff&#39; format.</li>
		<li>Acquire a minimum of four twenty-four bit color pictures (2200 &#181;m x 3400 &#181;m) per brain slice (6 sections per slide).</li>
	</ol>
	</li>
</ol>
6. Assessment of FITC-albumin Extravasation
<ol>
	<li>Analyze the fluorescence intensity for each single channel by using the freely available ImageJ14,15.</li>
	<li>Normalize the total fluorescent signal intensity of the FITC-albumin by the total CY3-Laminin fluorescent intensity per each image and report the extravasated albumin outside the vessels as Green Fluorescence Intensity.</li>
</ol>

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R., Betsholtz, C., Zlokovic, B. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+and+Dysfunction+of+the+Blood-Brain+Barrier.">Establishment and Dysfunction of the Blood-Brain Barrier.</a> Cell. 163 (5), 1064-1078 (2015).</li><li>Drouin-Ouellet, 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=Cerebrovascular+and+blood-brain+barrier+impairments+in+Huntington's+disease:+Potential+implications+for+its+pathophysiology.">Cerebrovascular and blood-brain barrier impairments in Huntington's disease: Potential implications for its pathophysiology.</a> Ann Neurol. 78 (2), 160-177 (2015).</li><li>Di Pardo, A., 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=Impairment+of+blood-brain+barrier+is+an+early+event+in+R6/2+mouse+model+of+Huntington+Disease.">Impairment of blood-brain barrier is an early event in R6/2 mouse model of Huntington Disease.</a> Sci Rep. 7, 41316 (2017).</li><li>Lecler, A., Fournier, L., Diard-Detoeuf, C., Balvay, D. <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+Leakage+in+Early+Alzheimer+Disease.">Blood-Brain Barrier Leakage in Early Alzheimer Disease.</a> Radiology. 282 (3), 923-925 (2017).</li><li>van de Haar, H. 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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=Transplantation+of+pancreatic+islets+into+the+kidney+capsule+of+diabetic+mice.">Transplantation of pancreatic islets into the kidney capsule of diabetic mice.</a> J Vis Exp. (9), e404 (2007).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+animal+perfusion+fixation+for+rodents.">Whole animal perfusion fixation for rodents.</a> J Vis Exp. (65), (2012).</li><li>McCloy, R. 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The authors have no conflicts of interest to disclose

The technique we describe here is primarily useful for detecting BBB leakage under brain disease conditions. BBB dysfunction is gaining attention as a common feature of diverse neurologic disorders4. We previously used this approach to describe the early derangement of BBB integrity in a mouse model of a rare neurodegenerative disease like HD6.
This method takes advantage of the relative simplicity and effectiveness of the procedure, which provid...

An erratum was issued for: <a href="https://www.jove.com/video/56389/assessment-blood-brain-barrier-permeability-intravenous-infusion-fitc">Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease</a>. One of the author&#39;s names was corrected from:
Maglione Vittorio
to:
Vittorio Maglione

An erratum was issued for: <a href="https://www.jove.com/video/56389/assessment-blood-brain-barrier-permeability-intravenous-infusion-fitc">Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease</a>. One of the author's names was corrected.

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

Homeostasis within the central nervous system (CNS) is a prerequisite for the proper communication and function of the neuronal cells. The CNS parenchyma is tightly sealed off from the periphery by the endothelial blood-brain barrier (BBB), which represents the interface between the peripheral bloodstream and the brain and plays a pivotal role in the cross-talk between these two districts1,2. The BBB is a complex and dynamic three-dimensional structure mainly composed of specialized micro-vessel endothelial cells (ECs) linked to each other through intercellular junctional complexes - tight junctions (TJs)- and surrounded by pericytes, neuron endings and astrocyte foot processes1,2.
Under physiological conditions, the extremely low permeability of the intact BBB ensures the strict regulation of the transport of nutrients and other molecules into and out of the brain, and provides the CNS with a unique protection from changes occurring in the composition of the blood that might influence neural activity and against potential peripheral insults1,2,3.
Disruption of BBB integrity and its enhanced permeability has long been known to constitute a key feature for many neurological and neurodegenerative disorders4 including Huntington&#39;s Disease (HD)5,6, however, whether such a dysfunction is a causative phenomenon or a propagative event in the course of the disease is still unclear. The timing of BBB breakdown also remains elusive, however, emerging evidence by our group and others indicates that disrupted BBB integrity does not represent a late event in the disease progression, but rather an early step6,7,8, which may have long-term consequences.
With this in mind, it is important to precociously reveal BBB breakdown in neurodegeneration in order to develop strategies useful to predict disease progression and brain damage and to develop alternative and more targeted interventions capable of successfully mitigating the clinical consequences of such a disruption. Reliable imaging of BBB impairment is, therefore, of major importance in both experimental research and clinical management of brain diseases.
In this paper, we describe a successful and simple procedure for the evaluation of BBB permeability in a HD mouse model by using the high molecular weight fluorescein isothiocyanate labelled-albumin (FITC-albumin). Extravasation of FITC-albumin, which normally cannot cross the barrier, into the brain parenchyma was measured as an index of BBB leakage. This technique is readily adaptable to rats and to other pathological conditions characterized by cerebrovasculature impairment9,10.

<table>
	<tbody>
		<tr>
			<td>Albumin-fluorescin isothiocyanate conjiugate</td>
			<td>SIGMA</td>
			<td>A9771-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>pAb anti-Laminin</td>
			<td>Novus Biologicals</td>
			<td>NB300-144</td>
			<td></td>
		</tr>
		<tr>
			<td>CY3 anti-rabbit made in goat</td>
			<td>MILLIPORE</td>
			<td>AP132</td>
			<td></td>
		</tr>
		<tr>
			<td>SUPERFROST PLUS</td>
			<td>Thermo Scientific</td>
			<td>J1800AMNZ</td>
			<td></td>
		</tr>
		<tr>
			<td>Cover Slips 24 X 50 mm</td>
			<td>Thermo Scientific (DIAPATH)</td>
			<td>61050</td>
			<td></td>
		</tr>
		<tr>
			<td>Kilik Optimal Cutting Temperature (OCT) compound</td>
			<td>Bio Optica</td>
			<td>05-9801</td>
			<td></td>
		</tr>
		<tr>
			<td>VECTASHIELD Mounting Media</td>
			<td>VECTOR</td>
			<td>H-1500</td>
			<td>Mounting media with DAPI</td>
		</tr>
		<tr>
			<td>iNSu/Light Insulin Disposible Syringe</td>
			<td>RAYS Health &#38;Safety</td>
			<td>INS1ML26G13</td>
			<td></td>
		</tr>
		<tr>
			<td>30G 1/2&#34;</td>
			<td>BD Microlance</td>
			<td>304000</td>
			<td>Needle for Insulin disposible Syringe</td>
		</tr>
		<tr>
			<td>Scalpel Handle</td>
			<td>F.S.T.</td>
			<td>91003-12</td>
			<td></td>
		</tr>
		<tr>
			<td>#22 Disposable Scalpel blads</td>
			<td>F.S.T.</td>
			<td>10022-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Iris scissors 10.5 cm</td>
			<td>F.S.T.</td>
			<td>14094-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont Forceps #5745 45&#176; 0.10 x 0.06 mm</td>
			<td>F.S.T.</td>
			<td>11251-35</td>
			<td></td>
		</tr>
		<tr>
			<td>Graefe Forceps 10 cm</td>
			<td>F.S.T.</td>
			<td>11051-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont Forceps #5 0.1 X 0.06 mm</td>
			<td>F.S.T.</td>
			<td>11251-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Medical patch</td>
			<td>Medicalis</td>
			<td>34788</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile disposable towel drape</td>
			<td>Dispotech</td>
			<td>TVO50VE</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereoscopic Microscope</td>
			<td>NIKON</td>
			<td>SMZ 745 T</td>
			<td></td>
		</tr>
		<tr>
			<td>Optic Illuminator LED light (C-FLED2)</td>
			<td>NIKON</td>
			<td>1003167</td>
			<td>Optic Illuminator for Stereoscopic Micrscope</td>
		</tr>
		<tr>
			<td>Eclipse Ni-U Microscope</td>
			<td>Nikon</td>
			<td>932162</td>
			<td>Epifluorescence Microscope</td>
		</tr>
		<tr>
			<td>Microscope digital Camera</td>
			<td>Nikon</td>
			<td>DS-Ri2</td>
			<td>Microscope camera</td>
		</tr>
		<tr>
			<td>Intenslight</td>
			<td>Nikon</td>
			<td>C-HGFI</td>
			<td>Microscope lamp</td>
		</tr>
		<tr>
			<td>NIS-Elements 64 bit</td>
			<td>Nikon</td>
			<td>AR 4.40.00</td>
			<td>Analysis Software</td>
		</tr>
		<tr>
			<td>Electric Razor</td>
			<td>Gemei</td>
			<td>GM-3007</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Proper infusion of FITC-albumin into the jugular vein results in the extravasation of the green fluorescence tracer from the bloodstream into the brain parenchymawhen the BBB is compromised6. Under physiological conditions, distribution of infused fluorescent albumin is restricted to the inside of the brain blood vessels and no signal in the surrounding perivascular area and/or brain parenchyma is detectable (Figure 1A, micrographs on ...

Watch this Scientific Journal Video about Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease at JoVE.com

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

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 ...

assessment-blood-brain-barrier-permeability-intravenous-infusion-fitc

Research

JoVE Journal

Neuroscience

9.8K Views.  IRCCS Neuromed. 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.

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

Methods for Intravenous Self Administration in a Mouse Model

Animal models have been developed to study the reinforcing effects of drugs, including the intravenous self-administration (IVSA) paradigm. The advantages of using an IVSA paradigm to study the reinforcing properties of drugs of abuse such as cocaine include the fact that the drug is self-administered instead of experimenter-administered, the schedule of reinforcement can be altered, and accurate measurement of the quantities of drug consumed as well as the timing and pattern of IV injections can be obtained. Furthermore, the intravenous route of administration avoids potential confounds related to first pass metabolism or taste, and produces rapid increases in blood and brain drug levels. As outlined in this video, intravenous self-administration can be obtained without prior food restriction or prior drug training following careful catheter placement during surgery and meticulous daily catheter flushing and maintenance. Experimental procedures outlined in this paper include a description of animal housing and acclimation methods, operant training using sweetened milk solutions, and catheter implantation surgery.

The intravenous self-administration (IVSA) paradigm is considered to be the gold standard in examining the reinforcing properties of drugs of abuse in rodents. This manuscript outlines the experimental procedures and surgical techniques necessary to obtain reliable IVSA data. In particular, meticulous catheter implantation and maintenance are highlighted.

Animal models have been developed to study the reinforcing effects of drugs, including the intravenous self-administration (IVSA) paradigm. The advantages ...

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 ...

Olfactory Assays for Mouse Models of Neurodegenerative Disease

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process and may be a useful behavioral marker for early detection. Earlier detection in neurodegenerative disease is a major goal in the field because this is when neuroprotective therapies have the best potential to be effective. Therefore, in preclinical studies testing novel neuroprotective strategies in rodent models of neurodegenerative disease, olfactory assessment could be highly useful in determining therapeutic potential of compounds and translation to the clinic. In the present study we describe a battery of olfactory assays that are useful in measuring olfactory function in mice. The tests presented in this study were chosen because they measure olfaction abilities in mice related to food odors, social odors, and non-social odors. These tests have proven useful in characterizing novel genetic mouse models of Parkinson&#8217;s disease as well as in testing potential disease-modifying therapies.

Impairment in olfactory function is a common feature in many neurodegenerative disorders including Parkinson, Alzheimer, and Huntington diseases. In the present article, we describe a set of tests for assessing olfaction discrimination and detection in mice that can be used to measure olfactory abilities in mouse models of neurodegenerative diseases.

In many neurodegenerative diseases and particularly in Parkinson&#8217;s disease, deficits in olfaction are reported to occur early in the disease process ...

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene expression in the mouse brain. Here we describe a technique first introduced by Passini and Wolfe for direct intracranial delivery of virally-encoded transgenes into the neonatal mouse brain. In its most basic form, the procedure requires only an ice bucket and a microliter syringe. However, the protocol can also be adapted for use with stereotaxic frames to improve consistency for researchers new to the technique. The method relies on the ability of adeno-associated virus (AAV) to move freely from the cerebral ventricles into the brain parenchyma while the ependymal lining is still immature during the first 12-24 hr after birth. Intraventricular injection of AAV at this age results in widespread transduction of neurons throughout the brain. Expression begins within days of injection and persists for the lifetime of the animal. Viral titer can be adjusted to control the density of transduced neurons, while co-expression of a fluorescent protein provides a vital label of transduced cells. With the rising availability of viral core facilities to provide both off-the-shelf, pre-packaged reagents and custom viral preparation, this approach offers a timely method for manipulating gene expression in the mouse brain that is fast, easy, and far less expensive than traditional germline engineering.

Here we demonstrate a technique for widespread neuronal transduction by intraventricular injection of adeno-associated virus into the neonatal mouse brain. This method provides a rapid and easy way to attain lifelong expression of virally-delivered transgenes.

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene ...

Quantitative Analysis of Climbing Defects in a Drosophila Model of Neurodegenerative Disorders

Locomotive defects resulting from neurodegenerative disorders can be a late onset symptom of disease, following years of subclinical degeneration, and thus current therapeutic treatment strategies are not curative. Through the use of whole exome sequencing, an increasing number of genes have been identified to play a role in human locomotion. Despite identifying these genes, it is not known how these genes are crucial to normal locomotive functioning. Therefore, a reliable assay, which utilizes model organisms to elucidate the role of these genes in order to identify novel targets of therapeutic interest, is needed more than ever. We have designed a sensitized version of the negative geotaxis assay that allows for the detection of milder defects earlier and has the ability to evaluate these defects over time. The assay is performed in a glass graduated cylinder, which is sealed with a wax barrier film. By increasing the threshold distance to be climbed to 17.5 cm and increasing the experiment duration to 2 min&#160;we have observed a greater sensitivity in detecting mild mobility dysfunctions. The assay is cost effective and does not require extensive training to obtain highly reproducible results. This makes it an excellent technique for screening candidate drugs in Drosophila mutants with locomotion defects.

We present an optimized inexpensive and reliable negative geotaxis assay in Drosophila melanogaster as a model for neurodegenerative disorders. Being more sensitive to mild locomotor defects, this assay will help screen for potential genetic interactions and drug targets.

Locomotive defects resulting from neurodegenerative disorders can be a late onset symptom of disease, following years of subclinical degeneration, and ...

Stereotaxic Infusion of Oligomeric Amyloid-beta into the Mouse Hippocampus

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the over-production of amyloid-beta and the deposition of amyloid-beta plaques in brain regions of the afflicted individuals. Throughout the years scientists have generated numerous Alzheimer&#8217;s disease mouse models that attempt to replicate the amyloid-beta pathology. Unfortunately, the mouse models only selectively mimic the disease features. Neuronal death, a prominent effect in the brains of Alzheimer&#8217;s disease patients, is noticeably lacking in these mice. Hence, we and others have employed a method of directly infusing soluble oligomeric species of amyloid-beta - forms of amyloid-beta that have been proven to be most toxic to neurons - stereotaxically into the brain. In this report we utilize male C57BL/6J mice to document this surgical technique of increasing amyloid-beta levels in a select brain region. The infusion target is the dentate gyrus of the hippocampus because this brain structure, along with the basal forebrain that is connected by the cholinergic circuit, represents one of the areas of degeneration in the disease. The results of elevating amyloid-beta in the dentate gyrus via stereotaxic infusion reveal increases in neuron loss in the dentate gyrus within 1 week, while there is a concomitant increase in cell death and cholinergic neuron loss in the vertical limb of the diagonal band of Broca of the basal forebrain. These effects are observed up to 2 weeks. Our data suggests that the current amyloid-beta infusion model provides an alternative mouse model to address region specific neuron death in a short-term basis. The advantage of this model is that amyloid-beta can be elevated in a spatial and temporal manner.

Here, we present a protocol for direct stereotaxic brain infusion of amyloid-beta. This methodology provides an alternative in vivo mouse model to address the short-term effects of amyloid-beta on brain neurons.

Alzheimer&#8217;s disease is a neurodegenerative disease affecting the aging population. A key neuropathological feature of the disease is the ...

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 ...

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.

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.

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

A Human Blood-Brain Interface Model to Study Barrier Crossings by Pathogens or Medicines and Their Interactions with the Brain

The early screening of nervous system medicines on a pertinent and reliable in cellulo BBB model for their penetration and their interaction with the barrier and the brain parenchyma is still an unmet need. To fill this gap, we designed a 2D in cellulo model, the BBB-Minibrain, by combining a polyester porous membrane culture insert human BBB model with a Minibrain formed by a tri-culture of human brain cells (neurons, astrocytes and microglial cells). The BBB-Minibrain allowed us to test the transport of a neuroprotective drug candidate (e.g., Neurovita), through the BBB, to determine the specific targeting of this molecule to neurons and to show that the neuroprotective property of the drug was preserved after the drug had crossed the BBB. We have also demonstrated that BBB-Minibrain constitutes an interesting model to detect the passage of virus particles across the endothelial cells barrier and to monitor the infection of the Minibrain by neuroinvasive virus particles. The BBB-Minibrain is a reliable system, easy to handle for researcher trained in cell culture technology and predictive of the brain cells phenotypes after treatment or insult. The interest of such in cellulo testing would be twofold: introducing derisking steps early in the drug development on the one hand and reducing the use of animal testing on the other hand.

Here we present a protocol describing the setting of an in cellulo BBB (Blood brain barrier)-Minibrain polyester porous membrane culture insert system in order to evaluate the transport of biomolecules or infectious agents across a human BBB and their physiological impact on the neighboring brain cells.

The early screening of nervous system medicines on a pertinent and reliable in cellulo BBB model for their penetration and their interaction with the ...