Name: assessment of dopaminergic homeostasis in mice by use of high-performance liquid chromatography analysis and synaptosomal dopamine uptake
Uploaded: 2017-09-21T12:30:00
Description: Watch this Scientific Journal Video about Assessment of Dopaminergic Homeostasis in Mice by Use of High-performance Liquid Chromatography Analysis and Synaptosomal Dopamine Uptake at JoVE.com

This work was supported by the UCPH 2016 Program of Excellence (U.G., A.R., K.J.), the Lundbeck Foundation (M.R.) the Lundbeck Foundation Center for Biomembranes in Nanomedicine (U.G.), the National Institute of Health Grants P01 DA 12408 (U.G.), the Danish Council for independent Research - Medical Sciences (U.G.).

The guidelines of the Danish Animal Experimentation Inspectorate (permission number: 2017-15-0201-01160) was followed and experiments performed in a fully AAALAC accredited facility under the supervision of a local animal welfare committee.
1. Synaptosomal Dopamine Uptake (Method 1)
NOTE: This protocol is for parallel assessment of two brains, but can be successfully used to perform synaptosomal DA uptake experiments with four brains in parallel.
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This manuscript describes useful experimental protocols to delineate DA homeostasis in any mouse model of choice. We provide detailed protocols for measuring levels of DA in brain tissue from mice using HPLC and synaptosomal DA uptake to assess functional DA transport through DAT. The procedures, protocols and limits for the HPLC experiment and synaptosomal DA uptake assay will be elaborated below.
The synaptosomal uptake protocol can provide useful insight to the functionality of DAT. Combine...

Dopamine (DA) is a modulatory neurotransmitter critical for motor behaviour, reward and cognitive function1,7,8,9. Imbalances in DA homeostasis are implicated in several neuropsychiatric diseases such as attention-deficit hyperactivity disorder, drug addiction, depression and Parkinson&#39;s disease1. DA is released from the presynaptic neuron into the synaptic cleft, where it binds to and activates receptors on the pre- and postsynaptic membrane, thereby further conveying the signal. The level of DA in the synapse after release is spatially and temporally controlled by DAT3,10. The transporter sequesters DA from the extracellular space, and thus sustains physiological DA levels3,11. Genetic removal of DAT in mice causes a hyperdopaminergic phenotype characterized by elevated synaptic DA levels, depletion of intracellular DA pools and profound changes in postsynaptic DAergic signalling10,12.
Here, two separate protocols are presented, one method to measure DA tissue content and another to assess the functionality of DAT. Combined with the surface biotinylation assay described by Gabriel et al.13 these two methods provide information on DA content and functional levels of DAT for a thorough assessment of DA homeostasis. With these methods DA homeostasis of various transgenic mice or disease models can be characterized and described. These tools have been implemented and optimized and are standard use in our laboratories. Current assays have served to investigate the consequences on the DA homeostasis of altering the C-terminal of DAT14 or expressing Cre recombinase under the tyrosine hydroxylase (TH) promoter 5.

<table>
	<tbody>
		<tr>
			<td>COMT inhibitor</td>
			<td>Sigma Aldrich, Germany</td>
			<td>RO-41-0960</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>[3H]-Dopamine</td>
			<td>Perkin-Elmer Life Sciences, Boston, MA, USA</td>
			<td>NET67-3001MC</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Glass microfiber filters</td>
			<td>GF/C Whatman, GE Healthcare Life Sciences, Buckinghamshire</td>
			<td>1822-024</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>HiSafe Scintillation fluid</td>
			<td>Perkin Elmer</td>
			<td>1200-437</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>MicroBeta2</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>BCA Protein Assay kit</td>
			<td>Thermo Scientific Pierce</td>
			<td>23225</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma Life Science</td>
			<td>H3375</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma Life Science</td>
			<td>S7903</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma Life Science</td>
			<td>S3014</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma Life Science</td>
			<td>P9541</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Merck KGaA</td>
			<td>10043-52-4</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Sigma Life Science</td>
			<td>63065</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Ascorbic Acid</td>
			<td>Sigma Life Science</td>
			<td>A0278</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>D-Glucose</td>
			<td>Sigma Life Science</td>
			<td>G7021</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Pargyline</td>
			<td>Sigma Aldrich</td>
			<td>P-8013</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Desipramine</td>
			<td>Sigma Aldrich</td>
			<td>D3900</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Dopamine</td>
			<td>Sigma Life Science</td>
			<td>H8502</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Cocaine</td>
			<td>Sigma Life Science</td>
			<td>C5776</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Brain matrix</td>
			<td>ASI instruments</td>
			<td>RBM2000C</td>
			<td>For synaptosomal DA uptake protocol</td>
		</tr>
		<tr>
			<td>Cafano mechanical teflon disrupter</td>
			<td>Buch &#38; Holm</td>
			<td>Discontinued</td>
			<td>For synaptosomal DA uptake protocol (homogenization)</td>
		</tr>
		<tr>
			<td>Antec Decade (Amperometric detector)</td>
			<td>Antec, Leiden, The Netherlands</td>
			<td>Discontinued: new model DECADE Elite / Lite&#8482; Electrochemical Detector type 175 and 176</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Avantec 0.22 &#956;m glass filter</td>
			<td>Frisenette ApS, Denmark</td>
			<td>13CP020AS</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Column: Prodigy 3 &#956; ODS-3 C18</td>
			<td>Phenomenex, YMC Europe, Chermbeck, Germany</td>
			<td>Part Number:00A-3300-E0</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>LC solution software</td>
			<td>Shimadzu</td>
			<td>LabSolutions Series Workstation</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Perchlor acid 0.1M</td>
			<td>Fluka Analytical</td>
			<td>35418-500ml</td>
			<td>For HPLC protocol (Tissue preparation)</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>E5134-50g</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Natriumdihydrogenphosphar</td>
			<td>Bie&#38;Berntsen</td>
			<td>1.06346 1000g</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Sodium 1-octanesulfonate monohydrate</td>
			<td>Aldrich</td>
			<td>74885 -10g</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Acetonitrile, isocratic HPLC grade</td>
			<td>Scharlau</td>
			<td>AC03402500</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Filtre 0.22um</td>
			<td>Frisenette ApS, Denmark</td>
			<td>Avantec 13CP020AS</td>
			<td>For HPLC protocol (Tissue preparation)</td>
		</tr>
		<tr>
			<td>ortho-Phosphoric acid 85%</td>
			<td>Merck</td>
			<td>1.00563. 1000ml</td>
			<td>For HPLC protocol</td>
		</tr>
		<tr>
			<td>Electrode</td>
			<td>Antec, Leiden, The Netherlands</td>
			<td>AN1161300</td>
			<td>For HPLC protocol (see manual online)</td>
		</tr>
		<tr>
			<td>Detector program on DECADE II electrochemical detector</td>
			<td>Antec, Leiden, The Netherlands</td>
			<td>Lite&#8482; Electrochemical Detector type 175 and 176</td>
			<td>For HPLC protocol</td>
		</tr>
	</tbody>
</table>

assessment of dopaminergic homeostasis in mice by use of high-performance liquid chromatography analysis and synaptosomal dopamine uptake

Dopamine (DA) is a modulatory neurotransmitter controlling motor activity, reward processes and cognitive function. Impairment of dopaminergic (DAergic) neurotransmission is strongly associated with several central nervous system-associated diseases such as Parkinson&#39;s disease, attention-deficit-hyperactivity disorder and drug addiction1,2,3,4. Delineating disease mechanisms involving DA imbalance is critically dependent on animal models to mimic aspects of the diseases, and thus protocols that assess specific parts of the DA homeostasis are important to provide novel insights and possible therapeutic targets for these diseases.
Here, we present two useful experimental protocols that when combined provide a functional read-out of the DAergic system in mice. Biochemical and functional parameters on DA homeostasis are obtained through assessment of DA levels and dopamine transporter (DAT) functionality5. When investigating the DA system, the ability to reliably measure endogenous levels of DA from adult brain is essential. Therefore, we present how to perform high-performance liquid chromatography (HPLC) on brain tissue from mice to determine levels of DA. We perform the experiment on tissue from dorsal striatum (dStr) and nucleus accumbens (NAc), but the method is also suitable for other DA-innervated brain areas.
DAT is essential for reuptake of DA into the presynaptic terminal, thereby controlling the temporal and spatial activity of released DA. Knowing the levels and functionality of DAT in the striatum is of major importance when assessing DA homeostasis. Here, we provide a protocol that allows to simultaneously deduce information on surface levels and function using a synaptosomal6 DA uptake assay.
Current methods combined with standard immunoblotting protocols provide the researcher with relevant tools to characterize the DAergic system.

Current DA uptake protocol (Figure 1) includes all steps necessary to assess the functionality of DAT in synaptosomes from mice. Our representative data of the DA uptake method (Figure 2) depicts a saturation curve with unadjusted data (Figure 2B) and adjusted data (Figure 2A). The saturation curve shows uptake from wild type mice. Usually one would make DA uptake for co...

Watch this Scientific Journal Video about Assessment of Dopaminergic Homeostasis in Mice by Use of High-performance Liquid Chromatography Analysis and Synaptosomal Dopamine Uptake at JoVE.com

Assessment of Dopaminergic Homeostasis in Mice by Use of High-performance Liquid Chromatography Analysis and Synaptosomal Dopamine Uptake

Synaptosomal dopamine uptake and high-performance liquid chromatography analysis represent experimental tools to investigate dopamine homeostasis in mice by assessing the function of the dopamine transporter and levels of dopamine in striatal tissue, respectively. Here we present protocols to measure dopamine tissue content and assess the functionality of the dopamine transporter.

Dopamine (DA) is a modulatory neurotransmitter controlling motor activity, reward processes and cognitive function. Impairment of dopaminergic (DAergic) ...

We are introducing two techniques in this protocol. The goal of the first, is to assess dopamine transporter function by measuring dopamine uptake from synaptosomal preparations. The second, is for assessing levels of dopamine in tissue by HPLC analysis.These methods provide important parameters of dopamine homeostasis by demonstrating how to measure dopamine tissue content and assess functionality of the dopamine transporter in mice. The main advantage of these techniques is that they can be performed post in-vivo manipulations such as, chemogenetic manipulations, in-vivo drug treatments or behavioral training of the animals. Demonstrating the HPLC procedure will be Pia Weikop, Associate Professor at the Laboratory of Neuropsychiatry.To begin this procedure, reveal the skull by cutting the skin and removing any excess tissue. Next, cut the skull along the sutura sagittalis, all the way anteriorly. Place the scissor tips in the eyes and remove the remaining skull by cutting through it.Rapidly remove the brain and place it in ice cold PBS. After that, using a brain matrix, dissect a three millimeter coronal slice of the striatum. Followed by finer dissection with a puncture.Subsequently, transfer the tissues to a 1.5 millimeter micro centrifuge tube for weighing. Then, repeat the procedures for the second brain. Once wait has been obtained for both brains, transfer the tissues to a homogenization glass containing one milliliter of ice cold homogenization buffer.After that, homogenize the tissue using a motor driven pestle. Next, transfer the homogeny to a 1.5 milliliter micro centrifuge tube and collect the remaining homogeny from the homogenization glass by rinsing it with 0.5 milliliters of additional homogenization buffer. Following that, pellet the nuclei and cell debris by centrifugation.Then, transfer the supernatant containing the cell membranes and cytoplasm to the new 1.5 milliliter micro centrifuge tubes and centrifuge for 20 minutes at four degree celsius. Afterward, discard the supernatant containing the cytoplasm and re-suspend the pellet containing crude synaptosomes in 40 microliters per milligram tissue in homogenization buffer. In this step, add 440 microliters of uptake buffer, ligand and cocaine to 12 designated 1.5 milliliter micro centrifuge tubes and 440 microliters of uptake buffer and ligand to the 36 remaining 1.5 milliliter micro centrifuge tubes.Label six two milliliter micro centrifuge tubes as 10, 5, 2.5, 1.25, 0.62 and 0.31. Then, add 750 microliters of uptake buffer and ligand to the five micro centrifuge tubes with the lowest number. Next, add 1, 455.4 microliters of uptake buffer and ligand, 14.6 microliters of unlabeled dopamine and 30 microliters of tritiated dopamine to the tube labeled, 10.Next, transfer 750 microliters of the mixture from the tube labeled 10, to the tube labeled 5. Mix well and transfer 750 microliters of the mixture from this tube to the tube labeled 2.5. Repeat this dilution with the remaining tubes.After that, pre-rinse the glass microfiber filters with four milliliters of uptake buffer after placing on a 12 well filter bucket. Following that, add 10 microliters of the synaptosomal membrane suspension to the first 24 1.5 milliliter micro centrifuge tubes containing 440 microliters buffer. Vortex carefully and spin down shortly to ensure that the synaptosomes are submerged in the buffer.Then, leave them at 37 degree celsius for 10 minutes. After 10 minutes, add 50 microliters of dopamine of 10 micromolar and five micromolar to the first two columns and leave them at 37 degrees celsius for five minutes with shaking. After five minutes, stop the reaction by adding one milliliter of ice cold uptake buffer, repeat it with the 2.5 micromolar and 1.25 micromolar and then, with the 0.62 micromolar and 0.31 micromolar.Add the samples to the pre-rinsed micro fiber filters and wash them with five, four milliliters of ice cold uptake buffer. After the first 12 samples have been added to the filters, move the filters to scintillation tubes. Repeat this with the next 12 samples.Prepare three max counting tubes by placing a microfiber filter in the bottom of scintillation tubes, 49 to 51 and adding 25 microliters of the maximum dopamine of 10 micromolar on top. Following this, leave all 51 scintillation tubes in a fume hood for one hour. Then, add three milliliters of scintillation fluid to each scintillation tube and shake vigorous on a shaker for one hour.To count tritiated dopamine in a beta counter for one minute, open the program and choose the suitable settings. For protein determination, use a standard BCA protein assay kit, to determine protein concentrations of the synaptosomes for adjustments and for proper comparison of uptake between samples. For tissue preparation, add 500 microliters of homogenization solution to each sample and homogenize all the samples using an ultra homogenizer on full speed for approximately 30 seconds.Keep the samples in iced water during homogenization. Next, centrifuge the samples for 30 minutes at four degree celsius, 14, 000 x G.After that, transfer approximately 200 microliters of each sample to a glass 0.22 micron filter before analyzing the samples by EC-HPLC methodology. To set up the detector, set the output to 700 millivolts and temperature at 32 degree celsius on the detector oven.Place the vials in the autosampler. Make a range program using the online manual and add the time program according to table two. Set up the system by opening the program.Next, type user ID and password and click okay. Then, wait for the program to connect to the instruments. Then, go to batch table and fill in data information.Save file by going to file, then click, save batch file as, followed by save. Subsequently, inject the first sample by pressing start batch. Afterward, go to data acquisition to follow the chromatogram when the samples are finished.Then, go to LC post run analysis and choose the file name. Then, click on view. On the manual integration bar, add all the peaks to be integrated, then, go to data report and print the readout.After the program has been added to the detector, make a three point calibration curve by injecting the prepared standard in five, 10 and 15 microliters. In this figure, the representative data depicts the saturation curve of dopamine uptake through the dopamine transporter from synaptosomal preparations in wild type mice. Black dots are the values of the four mice shown separately.The green curve shows how data would normally be depicted by combining data from four to six mice per group. Here is the saturation graph of the raw data before adjusting for actual protein concentration of the samples. This graph shows the counts from the cocaine containing samples which are used to subtract background from the uptake data.This control is essential to determine the reliability of the uptake data. This histogram shows the uptake capacity of the dopamine transporter and this histogram shows that Km for the dopamine transporter to be 0.1 plus or minus 0.03 micromolar which corresponds well to the rotating disk voltammetry method that depicts Km values of the dopamine transporter to be 0.6 to 1.2 micromolar. While attempting the synaptosomal optic procedure, it's important to keep tissue on ice at all times by preparing the synaptosomes.Following the synaptosome of dopamine uptake assay, additional procedures such as the surface biotinylation assay can be performed in order to determine whether a perturbed dopamine uptake can be explained by an altered surface expression of the dopamine transporter. After watching this video, you should have a good understanding of how to investigate dopamine homeostasis in mice by accessing the functionality of the dopamine transporter and dopamine levels in striatal tissue preparations.

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Research

JoVE Journal

Neuroscience

Assessment of Motor Balance and Coordination in Mice using the Balance Beam

Brain injury, genetic manipulations, and pharmacological treatments can result in alterations of motor skills in mice. Fine motor coordination and balance can be assessed by the beam walking assay. The goal of this test is for the mouse to stay upright and walk across an elevated narrow beam to a safe platform. This test takes place over 3 consecutive days: 2 days of training and 1 day of testing. Performance on the beam is quantified by measuring the time it takes for the mouse to traverse the beam and the number of paw slips that occur in the process. Here we report the protocol used in our laboratory, and representative results from a cohort of C57BL/6 mice. This task is particularly useful for detecting subtle deficits in motor skills and balance that may not be detected by other motor tests, such as the Rotarod.

Deficits in fine motor coordination can be assessed with the balance beam test. Performance on the beam is quantified by the speed at which the beam is traversed and the number of times the mouse slips on the beam.

Brain injury, genetic manipulations, and pharmacological treatments can result in alterations of motor skills in mice.  Fine motor coordination and ...

Reproducible Mouse Sciatic Nerve Crush and Subsequent Assessment of Regeneration by Whole Mount Muscle Analysis

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative response mounted by PNS neurons thereby possibly illuminating the failures of CNS regeneration1. Sciatic nerve crush (axonotmesis) is one of the most common models of peripheral nerve injury in rodents2. Crushing interrupts all axons but Schwann cell basal laminae are preserved so that regeneration is optimal3,4. This allows the investigator to study precisely the ability of a growing axon to interact with both the Schwann cell and basal laminae4. Rats have generally been the preferred animal models for experimental nerve crush. They are widely available and their lesioned sciatic nerve provides a reasonable approximation of human nerve lesions5,4. Though smaller in size than rat nerve, the mouse nerve has many similar qualities. Most importantly though, mouse models are increasingly valuable because of the wide availability of transgenic lines now allows for a detailed dissection of the individual molecules critical for nerve regeneration6, 7. Prior investigators have used multiple methods to produce a nerve crush or injury including simple angled forceps, chilled forceps, hemostatic forceps, vascular clamps, and investigator-designed clamps8,9,10,11,12. Investigators have also used various methods of marking the injury site including suture, carbon particles and fluorescent beads13,14,1. We describe our method to obtain a reproducibly complete sciatic nerve crush with accurate and persistent marking of the crush-site using a fine hemostatic forceps and subsequent carbon crush-site marking. As part of our description of the sciatic nerve crush procedure we have also included a relatively simple method of muscle whole mount we use to subsequently quantify regeneration.

In this report we describe a method to crush mouse sciatic nerve. This method uses readily available hemostatic forceps and easily and reproducibly produces complete sciatic nerve crush. In addition, we describe a method to prepare muscle whole mounts suitable for analysis of nerve regeneration after sciatic nerve crush.

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative ...

Assessing Neurodegenerative Phenotypes in Drosophila Dopaminergic Neurons by Climbing Assays and Whole Brain Immunostaining

Drosophila melanogaster is a valuable model organism to study aging and pathological degenerative processes in the nervous system. The advantages of the fly as an experimental system include its genetic tractability, short life span and the possibility to observe and quantitatively analyze complex behaviors. The expression of disease-linked genes in specific neuronal populations of the Drosophila brain, can be used to model human neurodegenerative diseases such as Parkinson's and Alzheimer's 5.
Dopaminergic (DA) neurons are among the most vulnerable neuronal populations in the aging human brain. In Parkinson's disease (PD), the most common neurodegenerative movement disorder, the accelerated loss of DA neurons leads to a progressive and irreversible decline in locomotor function. In addition to age and exposure to environmental toxins, loss of DA neurons is exacerbated by specific mutations in the coding or promoter regions of several genes. The identification of such PD-associated alleles provides the experimental basis for the use of Drosophila as a model to study neurodegeneration of DA neurons in vivo. For example, the expression of the PD-linked human &alpha;-synuclein gene in Drosophila DA neurons recapitulates some features of the human disease, e.g. progressive loss of DA neurons and declining locomotor function 2. Accordingly, this model has been successfully used to identify potential therapeutic targets in PD 8.
Here we describe two assays that have commonly been used to study age-dependent neurodegeneration of DA neurons in Drosophila: a climbing assay based on the startle-induced negative geotaxis response and tyrosine hydroxylase immunostaining of whole adult brain mounts to monitor the number of DA neurons at different ages. In both cases, in vivo expression of UAS transgenes specifically in DA neurons can be achieved by using a tyrosine hydroxylase (TH) promoter-Gal4 driver line 3, 10.

Assessing Neurodegenerative Phenotypes in Drosophila Dopaminergic Neurons by Climbing Assays and Whole Brain Immunostaining

Here we describe two assays that have been established to study age-dependent neurodegeneration of dopaminergic (DA) neurons in Drosophila: the climbing/startle-induced negative geotaxis assay which allows to study the functional effects of DA neurons degeneration and the tyrosine hydroxylase immunostaining which is used to identify and count DA neurons in whole brain mounts.

Drosophila melanogaster is a valuable model organism to study aging and pathological degenerative processes in the nervous system. The advantages of the ...

Primary Culture of Mouse Dopaminergic Neurons

Dopaminergic neurons represent less than 1% of the total number of neurons in the brain. This low amount of neurons regulates important brain functions such as motor control, motivation, and working memory. Nigrostriatal dopaminergic neurons selectively degenerate in Parkinson&#39;s disease (PD). This progressive neuronal loss is unequivocally associated with the motors symptoms of the pathology (bradykinesia, resting tremor, and muscular rigidity). The main agent responsible of dopaminergic neuron degeneration is still unknown. However, these neurons appear to be extremely vulnerable in diverse conditions. Primary cultures constitute one of the most relevant models to investigate properties and characteristics of dopaminergic neurons. These cultures can be submitted to various stress agents that mimic PD pathology and to neuroprotective compounds in order to stop or slow down neuronal degeneration. The numerous transgenic mouse models of PD that have been generated during the last decade further increased the interest of researchers for dopaminergic neuron cultures. Here, the video protocol focuses on the delicate dissection of embryonic mouse brains. Precise excision of ventral mesencephalon is crucial to obtain neuronal cultures sufficiently rich in dopaminergic cells to allow subsequent studies. This protocol can be realized with embryonic transgenic mice and is suitable for immunofluorescence staining, quantitative PCR, second messenger quantification, or neuronal death/survival assessment.

Dopaminergic neurons play a vital regulatory role in the brain. Their loss is associated with Parkinson's disease. In this video, we show how to generate primary cultures of central dopaminergic neurons from embryonic mouse mesencephalon. Such cultures are useful to study the extreme vulnerability of these neurons to various stresses.

Dopaminergic neurons represent less than 1% of the total number of neurons in the brain. This low amount of neurons regulates important brain functions ...

A High Content Imaging Assay for Identification of Botulinum Neurotoxin Inhibitors

Synaptosomal-associated protein-25 (SNAP-25) is a component of the soluble NSF attachment protein receptor (SNARE) complex that is essential for synaptic neurotransmitter release. Botulinum neurotoxin serotype A (BoNT/A) is a zinc metalloprotease that blocks exocytosis of neurotransmitter by cleaving the SNAP-25 component of the SNARE complex. Currently there are no licensed medicines to treat BoNT/A poisoning after internalization of the toxin by motor neurons. The development of effective therapeutic measures to counter BoNT/A intoxication has been limited, due in part to the lack of robust high-throughput assays for screening small molecule libraries. Here we describe a high content imaging (HCI) assay with utility for identification of BoNT/A inhibitors. Initial optimization efforts focused on improving the reproducibility of inter-plate results across multiple, independent experiments. Automation of immunostaining, image acquisition, and image analysis were found to increase assay consistency and minimize variability while enabling the multiparameter evaluation of experimental compounds in a murine motor neuron system.

Botulinum neurotoxin is one of the most potent toxins among Category-A biothreat agents, yet a post-exposure therapeutic is not available. The high content imaging approach is a powerful methodology for identifying novel inhibitors as it enables multiparameter screening using biologically relevant motor neurons, the primary target of this toxin.

Synaptosomal-associated protein-25 (SNAP-25) is a component of the soluble NSF attachment protein receptor (SNARE) complex that is essential for synaptic ...

Environmental Modulations of the Number of Midbrain Dopamine Neurons in Adult Mice

Long-lasting changes in the brain or &#8216;brain plasticity&#8217; underlie adaptive behavior and brain repair following disease or injury. Furthermore, interactions with our environment can induce brain plasticity. Increasingly, research is trying to identify which environments stimulate brain plasticity beneficial for treating brain and behavioral disorders. Two environmental manipulations are described which increase or decrease the number of tyrosine hydroxylase immunopositive (TH+, the rate-limiting enzyme in dopamine (DA) synthesis) neurons in the adult mouse midbrain. The first comprises pairing male and female mice together continuously for 1 week, which increases midbrain TH+ neurons by approximately 12% in males, but decreases midbrain TH+ neurons by approximately 12% in females. The second comprises housing mice continuously for 2 weeks in &#8216;enriched environments&#8217; (EE) containing running wheels, toys, ropes, nesting material, etc., which increases midbrain TH+ neurons by approximately 14% in males. Additionally, a protocol is described for concurrently infusing drugs directly into the midbrain during these environmental manipulations to help identify mechanisms underlying environmentally-induced brain plasticity. For example, EE-induction of more midbrain TH+ neurons is abolished by concurrent blockade of synaptic input onto midbrain neurons. Together, these data indicate that information about the environment is relayed via synaptic input to midbrain neurons to switch on or off expression of &#8216;DA&#8217; genes. Thus, appropriate environmental stimulation, or drug targeting of the underlying mechanisms, might be helpful for treating brain and behavioral disorders associated with imbalances in midbrain DA (e.g. Parkinson&#8217;s disease, attention deficit and hyperactivity disorder, schizophrenia, and drug addiction).

This protocol describes two different environmental manipulations and a concurrent brain infusion protocol to study environmentally-induced brain changes underlying adaptive behavior and brain repair in adult mice.

Long-lasting changes in the brain or &#8216;brain plasticity&#8217; underlie adaptive behavior and brain repair following disease or injury. Furthermore, ...

Assessment of Dendritic Arborization in the Dentate Gyrus of the Hippocampal Region in Mice

Dendritic arborization has been shown to be a reliable marker for examination of structural and functional integrity of neurons. Indeed, the complexity and extent of dendritic arborization correlates well with the synaptic plasticity in these cells. A reliable method for assessment of dendritic arborization is needed to characterize the deleterious effects of neurological disorders on these structures and to determine the effects of therapeutic interventions. However, quantification of these structures has proven to be a formidable task given their complex and dynamic nature. Fortunately, sophisticated imaging techniques can be paired with conventional staining methods to assess the state of dendritic arborization, providing a more reliable and expeditious means of assessment. Below is an example of how these imaging techniques were paired with staining methods to characterize the dendritic arborization in wild type mice. These complementary imaging methods can be used to qualitatively and quantitatively assess dendritic arborization that span a rather wide area within the hippocampal region.

We describe two methods for visualization and quantification of dendritic arborization in the hippocampus of mouse models: real-time and extended depth of field imaging. While the former method allows sophisticated topographical tracing and quantification of the extent of branching, the latter allows speedy visualization of the dendritic tree.

Dendritic arborization has been shown to be a reliable marker for examination of structural and functional integrity of neurons. Indeed, the complexity ...

Identification of Dopamine D1-Alpha Receptor Within Rodent Nucleus Accumbens by an Innovative RNA In Situ Detection Technology

In the central nervous system, the D1-alpha subtype receptor (Drd1&#945;) is the most abundant dopamine (DA) receptor, which plays a vital role in regulating neuronal growth and development. However, the mechanisms underlying Drd1&#945; receptor abnormalities mediating behavioral responses and modulating working memory function are still unclear. Using a novel RNA in situ hybridization assay, the current study identified dopamine Drd1&#945; receptor and tyrosine hydroxylase (TH) RNA expression from DA-related circuitry in the nucleus accumbens (NAc) area and substantia nigra region (SNR), respectively. Drd1&#945; expression in the NAc shows a &#34;discrete dot&#34; staining pattern. Clear sex differences in Drd1&#945; expression were observed. In contrast, TH shows a &#34;clustered&#34; staining pattern. Regarding TH expression, female rats displayed a higher signal expression per cell relative to male animals. The methods presented here provide a novel in situ hybridization technique for investigating changes in dopamine system dysfunction during the progression of central nervous system diseases.

Identification of Dopamine D1-Alpha Receptor Within Rodent Nucleus Accumbens by an Innovative RNA In Situ Detection Technology

Identification of dopamine D1-alpha receptor in the nucleus accumbens is critical for clarifying D1 receptor dysfunction during a central nervous system disease. We performed a novel RNA in situ hybridization assay to visualize single RNA molecules in a specific brain area.

In the central nervous system, the D1-alpha subtype receptor (Drd1&#945;) is the most abundant dopamine (DA) receptor, which plays a vital role in ...

Single Synapse Indicators of Glutamate Release and Uptake in Acute Brain Slices from Normal and Huntington Mice

Synapses are highly compartmentalized functional units that operate independently on each other. In Huntington&#39;s disease (HD) and other neurodegenerative disorders, this independence might be compromised due to insufficient glutamate clearance and the resulting spill-in and spill-out effects. Altered astrocytic coverage of the presynaptic terminals and/or dendritic spines as well as a reduced size of glutamate transporter clusters at glutamate release sites have been implicated in the pathogenesis of diseases resulting in symptoms of dys-/hyperkinesia. However, the mechanisms leading to the dysfunction of glutamatergic synapses in HD are not well understood. Improving and applying synapse imaging we have obtained data shedding new light on the mechanisms impeding the initiation of movements. Here, we describe the principle elements of a relatively inexpensive approach to achieve single synapse resolution by using the new genetically encoded ultrafast glutamate sensor iGluu, wide-field optics, a scientific CMOS (sCMOS) camera, a 473 nm laser and a laser positioning system to evaluate the state of corticostriatal synapses in acute slices from age appropriate healthy or diseased mice. Glutamate transients were constructed from single or multiple pixels to obtain estimates of i) glutamate release based on the maximal elevation of the glutamate concentration [Glu] next to the active zone and ii) glutamate uptake as reflected in the time constant of decay (TauD) of the perisynaptic [Glu]. Differences in the resting bouton size and contrasting patterns of short-term plasticity served as criteria for the identification of corticostriatal terminals as belonging to the intratelencephalic (IT) or the pyramidal tract (PT) pathway. Using these methods, we discovered that in symptomatic HD mice ~40% of PT-type corticostriatal synapses exhibited insufficient glutamate clearance, suggesting that these synapses might be at risk to excitotoxic damage. The results underline the usefulness of TauD as a biomarker of dysfunctional synapses in Huntington mice with a hypokinetic phenotype.

We present a protocol to evaluate the balance between glutamate release and clearance at single corticostriatal glutamatergic synapses in acute slices from adult mice. This protocol uses the fluorescent sensor iGluu for glutamate detection, a sCMOS camera for signal acquisition and a device for focal laser illumination.

Synapses are highly compartmentalized functional units that operate independently on each other. In Huntington&#39;s disease (HD) and other ...

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 ...