We want to acknowledge the struggles of all those with Parkinson&#39;s disease and the strength and resilience they show every day, especially the beloved father of KSC, Mark Steece. The work represented here was supported by the National Institute of Neurological Disorders and Stroke (NS090107, NS110398) and the Parkinson Disease Foundation International Research Grant Program, now the Parkinson Foundation.&#160;We also would like to acknowledge Molly VanderWerp for her excellent editorial assistance.

The animals presented here were maintained and handled in compliance with the institutional guidelines. All animal procedures were approved by the Michigan State University Institutional Animal Care and Use Committee (IACUC) in compliance with federal and state regulations.
1. Drug-free confirmation of 6-OHDA lesion status
<ol>
	<li>Postural Tail hang test11,12,13 
	NOTE: Assess lesion status at least 1 week following 6-OHDA&#160;lesion induction (See9,10,35&#160;for details on lesioning) in experimental subjects (e.g., male or female, adult Sprague Dawley or Fisher 344 rats).&#160;
	<ol>
		<li>Suspend the rat approximately 6 cm above its cage, firmly holding at the base of the tail, for ~5 s.</li>
		<li>Record the direction of body contortion as + for a successfully lesioned animal twisting contralateral to the lesioned side and - for lack of twisting or twisting in both directions.</li>
		<li>NOTE: These tests are optional but recommended. See14,15,16,17 for additional drug-free testing options/variations.</li>
	</ol>
	</li>
	<li>Step adjusting drag test (adapted from16) 
	NOTE: Assess lesion status at least 1 week following unilateral 6-OHDA lesion induction in experimental subjects (e.g., male or female, adult Sprague Dawley or Fisher 344 rats).
	<ol>
		<li>Hold the rat by the base of its tail, elevating the back feet off the surface by ~6 cm; drag backward across a flat, smooth but not slippery surface, ~75 cm, over 5&#8211;10 s.</li>
		<li>Observe and record the number of tapping/step adjusting movements of each forepaw over three repeated tests.</li>
		<li>Score the subject as + for successful unilateral lesioning when 0&#8211;2 forepaw taps are observed contralateral to the lesioned side, together with rapid tapping (~10 taps) from the forepaw ipsilateral to the lesioned side (e.g., animals unilaterally lesioned on the left side show tapping deficit (0&#8211;2 taps) with the contralateral right forepaw).</li>
		<li>Conversely, score moderate to rapid tapping (5&#8211;10 taps) from both forepaws as - to indicate incomplete or unknown lesion status. 
		NOTE: An anxious animal can show rapid tapping/step adjusting even if successfully lesioned. If this is suspected, place the rat back in their home cage and re-test &#8805;30 mins later.</li>
	</ol>
	</li>
</ol>
2. Preparation of reagents and supplies
<ol>
	<li>Determine L-3,4-dihydroxyphenylalanine methyl ester hydrochloride (levodopa or L-DOPA)&#160;and benserazide hydrochloride, a peripheral decarboxylase inhibitor (see Table of Materials) dose, rating frequency, and experimental timeline that is appropriate for the investigational question12,18,19,20 (Figure 1). 
	NOTE: Investigational questions can be posed to seek any number of questions ranging from asking whether a specific therapy might reduce existing LID or prevent induction of LID. They can also explore whether therapeutic efficacy is dependent on the dose of levodopa or whether LID expression and/or therapeutic efficacy varies depending on the sex, species, and age of the subject.</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62970/62970fig1v3.jpg" /> 
Figure 1: Example of treatment timeline. Example L-DOPA dose-escalation timeline of 12 weeks in total length, with 8 weeks of L-DOPA injections beginning 3 weeks after 6-OHDA lesioning and 4 weeks following experimental treatment. In this example, L-DOPA is subcutaneously injected 5x per week (Monday&#8211;Friday) at approximately the same time each day, for 2 weeks at each prescribed L-DOPA dose (3, 6, 9, and 12 mg/kg). Behavioral LID ratings take place on days 1, 6, and 10 of each L-DOPA dosage level. <a href="https://www.jove.com/files/ftp_upload/62970/62970fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Weigh rats weekly to calculate the appropriate drug quantity based on the ongoing weight changes during the study. 
	NOTE: Due to increased activity in LID+ rats, there is potential for weight loss with long-term L-DOPA treatments.&#160;If weight loss occurs provide rats with nutritionally complete, highly palatable treats (see Table of Materials) following L-DOPA injections.</li>
	<li>Calculate the amount of L-DOPA and benserazide required for each weekly concentration, weighing out lyophilized aliquots for each day of injection, and storing in combination for 1&#8211;2 weeks at -20 &#176;C in glass amber vials until the day of treatment. 
	NOTE: Target dose is 12 mg/kg or 12 mg L-DOPA/1000 g body weight. Example of calculations for determining the amount of L-DOPA and saline needed for each day of a week using 12 mg L-DOPA/kg body weight at an injection volume of 1 cc/kg of rat weight is given in Supplementary File 1.</li>
</ol>
3. Room and cage set up
<ol>
	<li>On the first day of L-DOPA treatment 3-4 weeks following 6-OHDA lesion surgery, transfer rats to single housing, including IACUC-approved enrichment.</li>
	<li>Maintain in single housing throughout the study to avoid peer interference with behavioral assessments.</li>
	<li>On LID rating days, place the home cages on a steel wire rack, turned at an approximately 45&#176; angle for optimal viewing of the rat (Figure 2A). Flip the identification tags (Figure 2B) upward and remove water bottles, food racks, and all types of enrichment in the cage (Figure 2C) to avoid interference with behavioral assessments.</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62970/62970fig02.jpg" /> 
Figure 2: Example of the cage set up for LID ratings of large-scale rat experiments. (A) Multiple cages can be set up for LID rating using large metal racks that allow for optimal viewing of each animal. Cages should be spread apart at a 45&#176; angle with ID cards flipped upward (B), food, water bottles, nesting materials, and other enrichment removed to limit visual obscureness of the rat and distractions to the rat while examining dyskinetic behaviors (C). The metal racks need to be a few feet away from any wall to allow the rater to examine the rat at the front or back of the cage as needed. It is essential to label enrichment apparatuses (e.g., C- red rat retreat houses) with individual animal IDs to replace them into the same cage from which they came. This is particularly important when using animals of different sexes not to increase stress to the experimental subjects. <a href="https://www.jove.com/files/ftp_upload/62970/62970fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
4. Levodopa injections and dyskinesia rating
<ol>
	<li>Subcutaneous injections of L-DOPA21,22
	<ol>
		<li>Immediately preceding the daily injection of L-DOPA, add the appropriate volume of sterile saline to the pre-weighed lyophilized L-DOPA and benserazide mix in the amber vial and shake well for 10 s (step 2.3). 
		NOTE: Target injection volume is 1 mL/1000 g body weight (with 12 mg L-DOPA per mL). The volume of the sterile saline will depend on the number of animals per study.</li>
		<li>Fill individual syringes (e.g., 1.0 or 0.5 mL with 26 G needle) with the required volume for each animal (1 mL/kg rat weight) and label each syringe with individual animal identification. 
		NOTE: Keep the filled syringes protected from light in sterile pouches until the time of injection. L-DOPA rapidly oxidizes in the presence of oxygen and light in an aqueous environment23,24,25,26.</li>
		<li>Bring the first cage to the injection bench.</li>
		<li>Remove the rat from its cage and place it on the injection surface.</li>
		<li>Gently restrain the head and shoulders against the surface on which the rat is resting with the palm of the non-dominant hand.</li>
		<li>Gently, scruff the skin on the back overlying the scapulae with the thumb and forefinger of the non-dominant hand, inject L-DOPA volume with the dominant hand into the subcutaneous space between/below the fingers, keeping the needle as parallel to the body as possible to avoid intramuscular injection. 
		&#8203;NOTE: The rats are not anesthetized before injection.</li>
		<li>Dispose of each used individual syringe in a sharp&#39;s container.</li>
		<li>Replace the rat into its individual cage and add nutritionally complete treats except on LID rating days to avoid interference with behavioral assessments until after ratings are complete.</li>
		<li>Set the timer for 1&#8211;2 min depending on the rating time desired and the number of rats in the study on rating days. Retrieve the next cage and inject the next rat when the timer indicates.</li>
		<li>Repeat this, injecting one rat every 1&#8211;2 min, until all the rats are injected.</li>
	</ol>
	</li>
	<li>Levodopa-induced dyskinesia rating post-injection
	<ol>
		<li>Rate the intensity (Table 1) and frequency (Table 2) of dystonic and hyperkinetic dyskinesia movements at the desired number of timepoints, which should include the initial onset of LID behavior, peak behavior, and the phase of decline (see Supplementary File 2 for an example of LID rating log sheet).</li>
		<li>For male and female adult Sprague Dawley or Fisher 344 rats, and a sample size of N = 40 rats, begin the dyskinesia ratings 20 min after the first L-DOPA injection, and then at 50 min intervals until 220 or 270 min post-injection, depending on when LID behaviors have discontinued in 90%&#8211;100% of rats.</li>
		<li>If using 1 min rating intervals, set a timer for 1 min. Rate the first rat for one minute. Move to the next rat and rate it for 1 min. Continue through all the rats, rating for 1 min intervals.</li>
		<li>Have a timer positioned next to the cage visibly so that the LID behavior intensity (Table 1) can be observed while estimating the frequency of any given behavior (Table 2) during the rating period.</li>
		<li>After ratings for the first time point are completed start again with the first rat at the next time point (e.g; 70 min post-injection) and continue at the desired interval (e.g., every 50 min) until all time points are completed. 
		NOTE: Due to the overlap of L-DOPA injection and LID rating tasks, two persons are needed on the rating days, one for injecting and one for behavioral ratings.</li>
	</ol>
	</li>
</ol>

No conflicts of interest were declared.

Presented here are details for the reproducible induction and rating of LIDs in a parkinsonian rat model following unilateral 6-OHDA lesioning of the nigrostriatal DA system. While it was once thought that rodents did not develop LID and that rotational asymmetry may be the analog of LID in rats31, rat and mouse models have been characterized over the past two decades and are a well-accepted tool for LID research15,32,<sup class...

Although it has been more than 50 years since levodopa (L-DOPA) was first introduced as a treatment for individuals with PD1,2, it remarkably remains the most effective therapy for parkinsonian motor symptoms. The clinical motor symptoms associated with PD stem from the loss of dopamine (DA) neurons in the substantia nigra (SN) pars compacta, resulting in the dramatic decrease in available dopamine in the striatum. L-DOPA effectively restores striatal DA levels, resulting in motor benefit early in the disease3,4. Inopportunely, with long-term treatment, most individuals with PD will develop&#160;L-DOPA induced dyskinesias (LID), including chorea, dystonia, and athetosis, which often significantly impact activities of daily living5,6,7.
While several behavioral models of LID in rodents exist, differences in modeling and behavioral assessment of LIDs have called into question the reproducibility of results between labs as well as the reliability of these experimental tools for pre-clinical PD research. Developed in association with a clinical movement disorder specialist8, the current protocol is a straightforward method for LID induction and rating and is appropriate for use in a rat model of PD utilizing 6-hydroxydopamine (6-OHDA)-induced unilateral nigral lesioning9,10. The LID rating scale provided here includes scoring for both the intensity and frequency of dyskinetic behavior in various individual body parts. Pertinent information regarding workflow optimization of experiments and the appropriate care and handling of parkinsonian and dyskinetic animals is also provided.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">&#160;100 Minutes Digital Timer</td>
			<td style="width:193px;">Staples</td>
			<td style="width:182px;">1111764</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">&#160;Compass CX Compact Scale</td>
			<td style="width:193px;">Ohaus</td>
			<td style="width:182px;">30428202</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">5-(2-aminoethyl)-1,2,4-benzenetriol, monohydrobromide</td>
			<td style="width:193px;">Cayman Chemicals</td>
			<td style="width:182px;">25330</td>
			<td style="width:559px;">6-OHDA is a catecholaminergic neurotoxin that is used to induce dopaminergic lesions and parkinsonian symptoms in rodents.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Allentown cages</td>
			<td style="width:193px;">Allentown, LLC</td>
			<td style="width:182px;">Rat900</td>
			<td style="width:559px;">Allentown cages provide the ability to view the rats from all sides.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">BD Allergist Trays with Permanently Attached Needle</td>
			<td style="width:193px;">BD</td>
			<td style="width:182px;">BD 305540</td>
			<td style="width:559px;">For subcutaneous L-DOPA injections</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:441px;">Benserazide hydrochloride</td>
			<td style="width:193px;">Sigma-Aldrich</td>
			<td style="width:182px;">B7283</td>
			<td style="width:559px;">Benserazide is a peripheral decarboxylase inhibitor used with L-DOPA to to induce dyskinesia in rodent models of PD.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Glass amber scintillation vials</td>
			<td style="width:193px;">Thermo Scientific</td>
			<td style="width:182px;">B7921</td>
			<td style="width:559px;">Used for storage of L-DOPA/benserazide at -20 &#176;C until mixed with sterile saline.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">L-3,4-Dihydroxyphenylalanine methyl ester hydrochloride</td>
			<td style="width:193px;">Sigma-Aldrich</td>
			<td style="width:182px;">D1507</td>
			<td style="width:559px;">L-3,4-Dihydroxyphenylalanine methyl ester is a precursor to&#160;L-DOPA that crosses the blood-brain barrierand use to treat parkinsonian symptoms in rodents.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Paper Mate Sharpwriter Mechanical Pencils</td>
			<td style="width:193px;">Staples</td>
			<td style="width:182px;">107250</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Rodent nutritionally complete enrichment treats</td>
			<td style="width:193px;">Bio-Serv</td>
			<td style="width:182px;">F05478</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Round Ice Bucket with Lid, 2.5 L</td>
			<td style="width:193px;">Corning</td>
			<td style="width:182px;">432129</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Standard Plastic Clipboard</td>
			<td style="width:193px;">Staples</td>
			<td style="width:182px;">1227770</td>
			<td style="width:559px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Steel wired 6&#39; long movable shelving units</td>
			<td style="width:193px;">Uline</td>
			<td style="width:182px;">H9488</td>
			<td style="width:559px;">Width/Height can be adjusted to need/number of rats per experiment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:441px;">Sterile Saline 0.9%</td>
			<td style="width:193px;">Covidien/Argyle</td>
			<td style="width:182px;">1020</td>
			<td style="width:559px;">For mixing with L-DOPA/benserazide prior to subcutaneous injections.</td>
		</tr>
	</tbody>
</table>

induction and assessment of levodopa-induced dyskinesias in a rat model of parkinson's disease

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

LIDs in parkinsonian rats can manifest as a range of abnormal involuntary movements (AIMs), including dystonic, hyperkinetic, and stereotypic behaviors. LID rating criteria for such behaviors are presented here to include both intensity (Table 1) and frequency (Table 2). This provides an overall LID severity score for each rat that reflects both the quality (intensity) and quantity of time spent engaging (frequency) in these behaviors at each rating timepoint. The final LID severity scor...

Watch this Scientific Journal Video about Induction and Assessment of Levodopa-induced Dyskinesias in a Rat Model of Parkinson's Disease at JoVE.com

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

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

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

induction-assessment-levodopa-induced-dyskinesias-rat-model-parkinson

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3.6K Views.  Michigan State University. This article describes methods to induce and evaluate levodopa-induced dyskinesias in a rat model of Parkinson's disease. The protocol offers detailed information regarding the intensity and frequency of a range of dyskinetic behaviors, both dystonic and hyperkinetic, providing a reliable tool to test treatments targeting this unmet medical need.

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

Methods to Characterize Spontaneous and Startle-induced Locomotion in a Rotenone-induced Parkinson's Disease Model of Drosophila

Parkinson&#8217;s disease is a neurodegenerative disorder that results from the degeneration of dopaminergic neurons in the central nervous system, primarily in the substantia nigra. The disease causes motor deficiencies, which present as rigidity, tremors and dementia in humans. Rotenone is an insecticide that causes oxidative damage by inhibiting the function of the electron transport chain in mitochondria. It is also used to model Parkinson&#8217;s disease in the Drosophila. Flies have an inherent negative geotactic response, which compels them to climb upwards upon being startled. It has been established that rotenone causes early mortality and locomotion defects that disrupt the flies&#8217; ability to climb after they have been tapped downwards. However, the effect of rotenone on spontaneous movement is not well documented. This study outlines two sensitive, reproducible, and high throughput assays to characterize rotenone-induced deficiencies in short-term startle-induced locomotion and long-term spontaneous locomotion in Drosophila. These assays can be conveniently adapted to characterize other Drosophila models of locomotion defects and efficacy of therapeutic agents.

Methods to Characterize Spontaneous and Startle-induced Locomotion in a Rotenone-induced Parkinson&#039;s Disease Model of Drosophila

Parkinson&#8217;s disease is a neurodegenerative disorder that results from the degeneration of dopaminergic neurons in the central nervous system, causing locomotion defects. Rotenone models Parkinson&#8217;s disease in Drosophila. This paper outlines two assays that characterize both spontaneous and startle-induced locomotion deficiencies caused by rotenone.

Parkinson&#8217;s disease is a neurodegenerative disorder that results from the degeneration of dopaminergic neurons in the central nervous system, ...

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

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

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

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

An In Vivo 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 ...

Generation of Alpha-Synuclein Preformed Fibrils from Monomers and Use In Vivo

Use of the in vivo alpha-synuclein preformed fibril (&#945;-syn PFF) model of synucleinopathy is gaining popularity among researchers aiming to model Parkinson&#39;s disease synucleinopathy and nigrostriatal degeneration. The standardization of &#945;-syn PFF generation and in vivo application is critical in order to ensure consistent, robust &#945;-syn pathology. Here, we present a detailed protocol for the generation of fibrils from monomeric &#945;-syn, post-fibrilization quality control steps, and suggested parameters for successful neurosurgical injection of &#945;-syn PFFs into rats or mice. Starting with monomeric &#945;-syn, fibrilization occurs over a 7-day incubation period while shaking at optimal buffer conditions, concentration, and temperature. Post-fibrilization quality control is assessed by the presence of pelletable fibrils via sedimentation assay, the formation of amyloid conformation in the fibrils with a thioflavin T assay, and electron microscopic visualization of the fibrils. Whereas successful validation using these assays is necessary for success, they are not sufficient to guarantee PFFs will seed &#945;-syn inclusions in neurons, as such aggregation activity of each PFF batch should be tested in cell culture or in pilot animal cohorts. Prior to use, PFFs must be sonicated under precisely standardized conditions, followed by examination using electron microscopy or dynamic light scattering to confirm fibril lengths are within optimal size range, with an average length of 50 nm. PFFs can then be added to cell culture media or used in animals. Pathology detectable by immunostaining for phosphorylated &#945;-syn (psyn; serine 129) is apparent days or weeks later in cell culture and rodent models, respectively.&#160;

The goal of this article is to outline the steps required for the generation of fibrils from monomeric alpha-synuclein, subsequent quality control, and use of the preformed fibrils in vivo.

Use of the in vivo alpha-synuclein preformed fibril (&#945;-syn PFF) model of synucleinopathy is gaining popularity among researchers aiming to model ...

Applying the RatWalker System for Gait Analysis in a Genetic Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta. Gait abnormalities, including decreased arm swing, slower walking speed, and shorter steps are common in PD patients and appear early in the course of disease. Thus, the quantification of motor patterns in animal models of PD will be important for phenotypic characterization during disease course and upon therapeutic treatment. Most cases of PD are idiopathic; however, the identification of hereditary forms of PD uncovered gene mutations and variants, such as loss-of-function mutations in Pink1 and Parkin, two proteins involved in mitochondrial quality control that could be harnessed to create animal models. While mice are resistant to neurodegeneration upon loss of Pink1 and Parkin (single and combined deletion), in rats, Pink1 but not Parkin deficiency leads to nigral DA neuron loss and motor impairment. Here, we report the utility of FTIR imaging to uncover gait changes in freely walking young (2 months of age) male rats with combined loss of Pink1 and Parkin prior to the development of gross visually apparent motor abnormality as these rats age (observed at 4-6 months), characterized by hindlimb dragging as previously reported in Pink1 knockout (KO) rats.

Here we describe the RatWalker system, built by redesigning the MouseWalker apparatus to accommodate for the increased size and weight of rats. This system uses frustrated total internal reflection (FTIR), high-speed video capture, and open-access analysis software to track and quantify gait parameters.

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the loss of dopaminergic (DA) neurons in the substantia nigra pars ...

Semi-Quantitative Determination of Dopaminergic Neuron Density in the Substantia Nigra of Rodent Models using Automated Image Analysis

Estimation of the number of dopaminergic neurons in the substantia nigra is a key method in pre-clinical Parkinson's disease research. Currently, unbiased stereological counting is the standard for quantification of these cells, but it remains a laborious and time-consuming process, which may not be feasible for all projects. Here, we describe the use of an image analysis platform, which can accurately estimate the quantity of labeled cells in a pre-defined region of interest. We describe a step-by-step protocol for this method of analysis in rat brain and demonstrate it can identify a significant reduction in tyrosine hydroxylase positive neurons due to expression of mutant &#945;-synuclein in the substantia nigra. We validated this methodology by comparing with results obtained by unbiased stereology. Taken together, this method provides a time-efficient and accurate process for detecting changes in dopaminergic neuron number, and thus is suitable for efficient determination of the effect of interventions on cell survival.

Here we present an automated method for semi-quantitative determination of dopaminergic neuron number in the rat substantia nigra pars compacta.

Estimation of the number of dopaminergic neurons in the substantia nigra is a key method in pre-clinical Parkinson's disease research. Currently, unbiased ...

A Rat Model of EcoHIV Brain Infection

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

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

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

The 6-hydroxydopamine Rat Model of Parkinson's Disease

Motor symptoms of Parkinson's disease (PD)-bradykinesia, akinesia, and tremor at rest-are consequences of the neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc) and dopaminergic striatal deficit. Animal models have been widely used to simulate human pathology in the laboratory. Rodents are the most used animal models for PD due to their ease of handling and maintenance. Moreover, the anatomy and molecular, cellular, and pharmacological mechanisms of PD are similar in rodents and humans. The infusion of the neurotoxin, 6-hydroxydopamine (6-OHDA), into a medial forebrain bundle (MFB) of rats reproduces the severe destruction of dopaminergic neurons and simulates PD symptoms. This protocol demonstrates how to perform the unilateral microinjection of 6-OHDA in the MFB in a rat model of PD and shows the motor deficits induced by 6-OHDA and predicted dopaminergic lesions through the stepping test. The 6-OHDA causes significant impairment in the number of steps performed with the contralateral forelimb.

The 6-hydroxydopamine (6-OHDA) model has been used for decades to advance the understanding of Parkinson's Disease. In this protocol, we demonstrate how to perform unilateral nigrostriatal lesions in the rat by injecting 6-OHDA in the medial forebrain bundle, assess motor deficits, and predict lesions using the stepping test.

Motor symptoms of Parkinson's disease (PD)-bradykinesia, akinesia, and tremor at rest-are consequences of the neurodegeneration of dopaminergic neurons in ...

Analyzing the Parkinson's Disease Mouse Model Induced by Adeno-associated Viral Vectors Encoding Human &#945;-Synuclein

Parkinson&#39;s disease is a neurodegenerative disorder that involves the death of the dopaminergic neurons of the nigrostriatal pathway and, consequently, the progressive loss of control of voluntary movements. This neurodegenerative process is triggered by the deposition of protein aggregates in the brain, which are mainly constituted of &#945;-synuclein. Several studies have indicated that neuroinflammation is required to develop the neurodegeneration associated with Parkinson&#39;s disease. Notably, the neuroinflammatory process involves microglial activation as well as the infiltration of peripheral T cells into the substantia nigra (SN). This work analyzes a mouse model of Parkinson&#39;s disease that recapitulates microglial activation, T-cell infiltration into the SN, the neurodegeneration of nigral dopaminergic neurons, and motor impairment. This mouse model of Parkinson&#39;s disease is induced by the stereotaxic delivery of adeno-associated viral vectors encoding the human wild-type &#945;-synuclein (AAV-h&#945;Syn) into the SN. The correct delivery of viral vectors into the SN was confirmed using control vectors encoding green fluorescent protein (GFP). Afterward, how the dose of AAV-h&#945;Syn administered in the SN affected the extent of h&#945;Syn expression, the loss of nigral dopaminergic neurons, and motor impairment were evaluated. Moreover, the dynamics of h&#945;Syn expression, microglial activation, and T-cell infiltration were determined throughout the time course of disease development. Thus, this study provides critical time points that may be useful for targeting synuclein pathology and neuroinflammation in this preclinical model of Parkinson&#39;s disease.

This work analyzes the vector dose and exposure time required to induce neuroinflammation, neurodegeneration, and motor impairment in this preclinical model of Parkinson&#39;s disease. These vectors encoding the human &#945;-synuclein are delivered into the substantia nigra&#160;to recapitulate the synuclein pathology associated with Parkinson&#39;s disease.

Parkinson&#39;s disease is a neurodegenerative disorder that involves the death of the dopaminergic neurons of the nigrostriatal pathway and, ...

Locomotor Assessment of 6-Hydroxydopamine-induced Adult Zebrafish-based Parkinson's Disease Model

The limitations of current treatments in delaying dopaminergic neuronal loss in Parkinson&#39;s disease (PD) raise the need for alternative therapies that can restore these neurons. Much effort is currently directed toward a better understanding of neuroregeneration using preclinical in vivo models. This regenerative capability for self-repair is, however, inefficient in mammals. Non-mammalian animals like zebrafish have thus emerged as an excellent neuroregenerative model due to its capability to continuously self-renew and have a close brain homology to humans. As part of the effort in elucidating cellular events involved in neuroregeneration in vivo, we have established the 6-hydroxydopamine (6-OHDA)-induced adult zebrafish-based PD model. This was achieved through the optimized intracerebroventricular (ICV) microinjection of 99.96&#160;mM 6-OHDA to specifically ablate dopaminergic neurons (DpN) in the ventral diencephalon (Dn) of zebrafish brain. Immunofluorescence indicated more than 85% of DpN ablation at day three postlesion and full restoration of DpN at lesioned site 30 days postlesion. The present study determined the impairment and subsequent recovery of zebrafish swimming behavior following lesion by using the open field test through which two parameters, distance traveled (cm) and mean speed (cm/s), were quantified. The locomotion was assessed by analyzing the recordings of individual fish of each group (n = 6) using video tracking software. The findings showed a significant (p &#60; 0.0001) reduction in speed (cm/s) and distance traveled (cm) of lesioned zebrafish 3 days postlesion when compared to sham. The lesioned zebrafish exhibited full recovery of swimming behavior 30 days postlesion. The present findings suggest that 6-OHDA lesioned adult zebrafish is an excellent model with reproducible quality to facilitate the study of neuroregeneration in PD. Future studies on the mechanisms underlying neuroregeneration as well as intrinsic and extrinsic factors that modulate the process may provide important insight into new cell replacement treatment strategies against PD.

The present protocol describes the intracerebroventricular (ICV) injection of adult zebrafish with neurotoxic 6-hydroxydopamine (6-OHDA) at the ventral diencephalon (Dn) and the assessment of the impairment and subsequent recovery of swimming behavior postlesion by using the open tank test, which is accompanied by analysis using a video tracking software.

The limitations of current treatments in delaying dopaminergic neuronal loss in Parkinson&#39;s disease (PD) raise the need for alternative therapies that ...