Name: identification of dopamine d1-alpha receptor within rodent nucleus accumbens by an innovative rna in situ detection technology
Uploaded: 2018-03-27T15:00:00
Description: Watch this Scientific Journal Video about Identification of Dopamine D1-Alpha Receptor Within Rodent Nucleus Accumbens by an Innovative RNA In Situ Detection Technology at JoVE.com

The present works were supported by National Institutes of Health (NIH) grants HD043680, MH106392, DA013137, and NS100624. Partial fund was provided by a NIH T32 training grant in Biomedical-Behavioral science.

The experimental protocol was approved by the Animal Care and Use Committee (IACUC) at the University of South Carolina (federal assurance number: A3049-01).
1. Preparation of Fresh Frozen Brain Sections
<ol>
	<li>Use the F344/N rat strain: three rats of each sex, 13 months of age, body weight approximately 320&#160;g.</li>
	<li>Adjust the sevoflurane concentration to 5% (overdose of sevoflurane). Continue sevoflurane exposure after breathing stops for an additional minute.</li>
	<li>Decapit...

<ol>
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J., Trezza, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dopaminergic+Neurotransmission+in+the+Nucleus+Accumbens+Modulates+Social+Play+Behavior+in+Rats.">Dopaminergic Neurotransmission in the Nucleus Accumbens Modulates Social Play Behavior in Rats.</a> Neuropsychopharmacology. 41 (9), 2215-2223 (2016).</li><li>Okubo, Y., 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=Decreased+prefrontal+dopamine+D1+receptors+in+schizophrenia+revealed+by+PET.">Decreased prefrontal dopamine D1 receptors in schizophrenia revealed by PET.</a> Nature. 385 (6617), 634-636 (1997).</li><li>Abi-Dargham, 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=Prefrontal+dopamine+D1+receptors+and+working+memory+in+schizophrenia.">Prefrontal dopamine D1 receptors and working memory in schizophrenia.</a> J Neurosci. 22 (9), 3708-3719 (2002).</li><li>Shinohara, R., 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=Dopamine+D1+receptor+subtype+mediates+acute+stress-induced+dendritic+growth+in+excitatory+neurons+of+the+medial+prefrontal+cortex+and+contributes+to+suppression+of+stress+susceptibility+in+mice.">Dopamine D1 receptor subtype mediates acute stress-induced dendritic growth in excitatory neurons of the medial prefrontal cortex and contributes to suppression of stress susceptibility in mice.</a> Mol Psychiatry. 19, (2017).</li><li>Okubo, Y., 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=Decreased+prefrontal+dopamine+D1+receptors+in+schizophrenia+revealed+by+PET.">Decreased prefrontal dopamine D1 receptors in schizophrenia revealed by PET.</a> Nature. 385, 634-636 (1997).</li><li>Wang, F., 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=RNAscope:+a+novel+in+situ+RNA+analysis+platform+for+formalin-fixed,+paraffin-embedded+tissues.">RNAscope: a novel in situ RNA analysis platform for formalin-fixed, paraffin-embedded tissues.</a> J Mol Diagn. 14 (1), 22-29 (2012).</li><li>Paxinos, G., Watson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The rat brain in stereotaxic coordinates. , (2014).</li></ol>

In this protocol, we describe a novel technique of in situ hybridization for fresh-frozen brain slices to evaluate Drd1&#945; receptor expression in the nucleus accumbens (NAc) and tyrosine hydroxylase (TH) expression in the substantia nigra (SNR) region. We also provide methods of data analysis for different staining patterns: &#34;discrete dot&#34; or &#34;clusters&#34;.
The critical steps for a successful multiplex fluorescence RNA in situ hybridization assay are included....

Dysfunction of the striatal dopamine system is involved in the progression of clinical symptoms observed in multiple neurocognitive diseases. Dopamine D1 receptors are present in the prefrontal cortex (PFC) and striatal regions of the brain and heavily influence cognitive processes1, including working memory, temporal processing, and locomotive behavior2,3,4,5,6,7. Previous studies elucidated that changes of dopamine D1 receptors were associated with the progression of attention deficit-hyperactivity disorder (ADHD)8, the neurocognitive symptoms in schizophrenia9,10 and stress susceptibility11. Specifically, in schizophrenia, positron emission tomography (PET) studies indicated that the binding ability of dopamine D1 receptors in the prefrontal cortices was highly related to cognitive deficits and the presence of negative symptoms11. The dendritic growth of excitatory neurons in the prefrontal cortex regulated by the dopamine D1 receptor alleviates stress susceptibility. Furthermore, the knockdown of D1 receptor in medial prefrontal cortical (mPFC) neurons could enhance the social defeat stress-induced social avoidance12.
Here, we introduce a novel technique of RNA in situ hybridization to visualize single RNA molecules in a cell with fresh-frozen tissue samples. The present technique has multiple advantages over methods that exist within the current literature. First, the current procedure preserves the spatial and morphological context of the tissue and was performed on fresh-frozen tissue samples so that other procedures requiring fresh, non-embedded tissues may be combined with the current methods. Similar procedures in formalin-fixed and paraffin-embedded tissues have illustrated that single transcription resolution can be achieved using an RNA in situ hybridization technique13. Detection of RNA at the single transcription level provides superior sensitivity to low copy number expression as well as the opportunity to compare gene expression at the level of individual cells that cannot be achieved by other nucleic acid detection methods, such as polymerase chain reaction (PCR) techniques. Additionally, the current method maintains images with a high signal-to-noise ratio through highly specific RNA probes that are hybridized to single target RNA transcripts, and sequentially bound with a cascade of signal amplification molecules in the detection system. Finally, the present technology provides the opportunity to evaluate multiple biological systems with its target-specific proprietary probes, rather than limiting our investigation to only one class of system-related markers such as protein detection by immunohistochemistry methods.
In our study, we used this novel RNA in situ hybridization to evaluate Drd1&#945; receptor expression in the nucleus accumbens (NAc) and tyrosine hydroxylase (TH) expression in the substantia nigra (SNR) of both male and female F344/N rats. The innovative RNA in situ hybridization enabled us to investigate mechanisms influencing both DA uptake and DA release simultaneously, improving our understanding of the striatal DA system&#39;s complexities. Here, we describe the procedure for fresh-frozen brain slices and provide methods of data analysis for different staining patterns: &#34;discrete dot&#34; or &#34;clusters&#34;.

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			<td>version 9.4</td>
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</table>

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.

The current study observed a &#34;discrete dots&#34; staining pattern for RNA expression in the dopamine D1-alpha receptors (Drd1&#945;) of the NAc in F344/N rats (Figure 1A). Individual fluorescence signals were easily identified and can be seen as single &#34;dots,&#34; each of which represents a single RNA transcript within the cell. For images from the NAc that display the &#34;discrete dots&#34; staining pattern, we assessed the dynamic range of expressi...

Watch this Scientific Journal Video about Identification of Dopamine D1-Alpha Receptor Within Rodent Nucleus Accumbens by an Innovative RNA In Situ Detection Technology at JoVE.com

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.

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 ...

The overall goal of this novel RNA in-situ hybridization assay is to visualize single RNA molecules in a specific brain area which are critical for clarifying dopaminergic dysfunction during central nervous system disease. This method can help answer key questions in the neuroscience field such as dopaminergic abnormalities mediating behavioral responses and modulating working memory function. The main advantage of this method is that it provides a novel in-situ hybridization technique to investigate dopamine system dysfunction during the progression of central nervous system diseases.Though this method can provide insight into overall expression levels of a target mRNA in a given brain region, it can also be applied to determine how mRNA transcripts are distributed throughout the cells of a given region. To begin this procedure, within five minutes after harvesting an adult rat brain, submerge it in liquid nitrogen for 15 seconds. Next, equilibrate the brain at minus 20 degrees Celsius in a cryostat for one hour.After an hour, cut 30 micron sections containing nucleus accumbens from 2.76 millimeters to 2.28 millimeters anterior to bregma and mount them onto the slides. Then dry the sections at minus 20 degrees Celsius for 10 minutes. Subsequently, immerse the slides in pre-chilled 4%paraformaldehyde for one hour at four degrees Celsius.Next, place the slides in an increasing ethanol gradient at room temperature then transfer the slides to fresh 100%ethanol for another five minutes. Afterward, place the slides on the absorbent paper to allow air dry. Draw a barrier around each section with a barrier pen.Let the barrier dry completely for one minute. To pre-treat the brain sections, turn on the oven and set the temperature to 40 degrees Celsius. Add three drops of pre-treatment reagent on each brain section.Then incubate the sections for 30 minutes at room temperature. Next, submerge the slides in 1X PBS for one minute at room temperature and transfer the slides to fresh 1X PBS for another minute. Slides should not stay in 1X PBS for longer than 15 minutes.To run the multiplex assay, warm the target probe for 10 minutes at 40 degrees Celsius in a water bath and then cool to room temperature. Place the RNA reagent at room temperature. Remove excess liquid from the slides with absorbent paper and place them back on the slide rack.Then add three drops of the Drd1alpha as probe on each sample slice and incubate the samples for two hours at 40 degrees Celsius. Afterward, wash the slides in 1X wash buffer for two minutes at room temperature twice. Then remove excess liquid from the slides with absorbent paper and place them back on the slide rack.Do not let brain sections dry out between incubation steps. Add three drops of AMP 1FL on each sample slice and incubate the samples for 30 minutes at 40 degrees Celsius. Afterward, wash the slides twice in 1X wash buffer for two minutes each time at room temperature.Then remove excess liquid from the slides with absorbent paper and place them back on the slide rack. Subsequently, add three drops of AMP 2FL on each sample slice. Incubate the samples for 15 minutes at 40 degrees Celsius.Next, submerge the slides in 1X wash buffer for two minutes at room temperature twice. Remove excess liquid from the slides with absorbent paper and place them back on the slide rack. Add three drops of AMP 3FL on each sample slice and incubate the samples for 30 minutes at 40 degrees Celsius.Next, wash the slides in 1X wash buffer for two minutes at room temperature twice. Remove excess liquid from the slides with absorbent paper and place them back on the slide rack. Then add three drops of AMP 4FL ALT A on each sample slice and incubate the samples for 15 minutes at 40 degrees Celsius.Wash the slide in 1X wash buffer for two minutes at room temperature twice. Remove excess liquid from the slides and immediately place two drops of mounting reagent onto each section. Next, place a 22 millimeter by 22 millimeter coverslip over each brain section.Then store the slides in the dark at two to eight degrees Celsius until dry. For imaging, turn on the confocal microscope and switch to a 60X objective. Obtain Z stack images and acquire images of Drd1alpha-labeled cells in the nucleus accumbens region.For images from the nucleus accumbens that displayed the discrete dots staining pattern, the dynamic range of expression was assessed using a semi-quantitative analysis. Each cell was scored from zero to nine based on the number of dots per cell. This hybridized signal score method can thus assess the extent and variability for Drd1alpha expression across individual cells.Here are the representative confocal images of Drd1alpha expression in male and female rats which have the discrete dots staining pattern. To account for the nested data structure, average count values were calculated for each category and used for statistical analysis. A Mann-Whitney U test was conducted to assess differences in median cell count in male and female rats.The frequency of cells in each category is analyzed using relative frequency and cumulative frequency. Female animals displayed a significant shift in the distribution with the greater frequency of cells in lower ordered categories relative to male animals. Overall, the results suggest clear sex differences in Drd1alpha expression in the nucleus accumbens.Once mastered, this technique can be done in seven hours if it is performed properly. While attempting this procedure, it's important to remember to work quickly as temperature changes or drying out of the tissue can damage the mRNA and hinder our ability to obtain a reliable signal. After watching this video, you should have a good understanding of how to perform the in-situ hybridization technique in cortical tissues, fluorescently image signal mRNA transcripts within chosen brain regions, and characterize the distribution of mRNA transcripts for statistical analysis.

identification-dopamine-d1-alpha-receptor-within-rodent-nucleus

Research

JoVE Journal

Neuroscience

Simultaneous fMRI and Electrophysiology in the Rodent Brain

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in which functional MRI data and in vivo intracortical recording can be performed simultaneously. The combination of MRI and electrical recording is technically challenging because the electrodes used for recording distort the MRI images and the MRI acquisition induces noise in the electrical recording. To minimize the mutual interference of the two modalities, glass microelectrodes were used rather than metal and a noise removal algorithm was implemented for the electrophysiology data. In our studies, two microelectrodes were separately implanted in bilateral primary somatosensory cortices (SI) of the rat and fixed in place. One coronal slice covering the electrode tips was selected for functional MRI. Electrode shafts and fixation positions were not included in the image slice to avoid imaging artifacts. The removed scalp was replaced with toothpaste to reduce susceptibility mismatch and prevent Gibbs ringing artifacts in the images. The artifact structure induced in the electrical recordings by the rapidly-switching magnetic fields during image acquisition was characterized by averaging all cycles of scans for each run. The noise structure during imaging was then subtracted from original recordings. The denoised time courses were then used for further analysis in combination with the fMRI data. As an example, the simultaneous acquisition was used to determine the relationship between spontaneous fMRI BOLD signals and band-limited intracortical electrical activity. Simultaneous fMRI and electrophysiological recording in the rodent will provide a platform for many exciting applications in neuroscience in addition to elucidating the relationship between the fMRI BOLD signal and neuronal activity.

We have developed a method for simultaneous functional magnetic resonance imaging and electrophysiological recording in the rodent brain, providing a platform for the investigation of the relationship between neural activity and the blood oxygenation level dependent (BOLD) MRI signal.

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in ...

VisioTracker, an Innovative Automated Approach to Oculomotor Analysis

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, robust, and simple to manipulate. A suitable model has been found in the optokinetic response (OKR), a reflexive behavior present in all vertebrates due to its high selection value. The OKR involves slow stimulus-following movements of eyes alternated with rapid resetting saccades. The measurement of this behavior is easily carried out in zebrafish larvae, due to its early and stable onset (fully developed after 96 hours post fertilization (hpf)), and benefitting from the thorough knowledge about zebrafish genetics, for decades one of the favored model organisms in this field. Meanwhile the analysis of similar mechanisms in adult fish has gained importance, particularly for pharmacological and toxicological applications.
Here we describe VisioTracker, a fully automated, high-throughput system for quantitative analysis of visual performance. The system is based on research carried out in the group of Prof. Stephan Neuhauss and was re-designed by TSE Systems. It consists of an immobilizing device for small fish monitored by a high-quality video camera equipped with a high-resolution zoom lens. The fish container is surrounded by a drum screen, upon which computer-generated stimulus patterns can be projected. Eye movements are recorded and automatically analyzed by the VisioTracker software package in real time.
Data analysis enables immediate recognition of parameters such as slow and fast phase duration, movement cycle frequency, slow-phase gain, visual acuity, and contrast sensitivity.
Typical results allow for example the rapid identification of visual system mutants that show no apparent alteration in wild type morphology, or the determination of quantitative effects of pharmacological or toxic and mutagenic agents on visual system performance.

The VisioTracker is an automated system for the quantitative analysis of visual performance of larval and small adult fish based on the recording of eye movements. It features full control over visual stimulus properties and real-time analysis, enabling high-throughput research in fields such as visual system development and function, pharmacology, neural circuit studies and sensorimotor integration.

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, ...

Direct Intraventricular Delivery of Drugs to the Rodent Central Nervous System

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses specifically on antisense oligonucleotides (ASOs), though the techniques shown in the video here can also be used to deliver a plethora of other drugs to the CNS. Antisense oligonucleotides (ASOs) have the capability to knockdown sequence-specific targets 1 as well as shift isoform ratios of specific genes 2. To achieve widespread gene knockdown or splicing in the CNS of mice, the ASOs can be delivered into the brain using two separate routes of administration, both of which we demonstrate in the video.
The first uses Alzet osmotic pumps, connected to a catheter that is surgically implanted into the lateral ventricle. This allows the ASOs to be continuously infused into the CNS for a designated period of time. The second involves a single bolus injection of a high concentration of ASO into the right lateral ventricle. Both methods use the mouse cerebral ventricular system to deliver the ASO to the entire brain and spinal cord, though depending on the needs of the study, one method may be preferred over the other.

We describe a method to target drugs to the central nervous system by either implanting a catheter or performing a bolus injection into the right lateral ventricle in mice. We focus specifically on the delivery of antisense oligonucleotides. This technique is readily adaptable to other drugs and to rats.

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses ...

Detection of the Genome and Transcripts of a Persistent DNA Virus in Neuronal Tissues by Fluorescent In situ Hybridization Combined with Immunostaining

Single cell codetection of a gene, its RNA product and cellular regulatory proteins is critical to study gene expression regulation. This is a challenge in the field of virology; in particular for nuclear-replicating persistent DNA viruses that involve animal models for their study. Herpes simplex virus type 1 (HSV-1) establishes a life-long latent infection in peripheral neurons. Latent virus serves as reservoir, from which it reactivates and induces a new herpetic episode. The cell biology of HSV-1 latency remains poorly understood, in part due to the lack of methods to detect HSV-1 genomes in situ in animal models. We describe a DNA-fluorescent in situ hybridization (FISH) approach efficiently detecting low-copy viral genomes within sections of neuronal tissues from infected animal models. The method relies on heat-based antigen unmasking, and directly labeled home-made DNA probes, or commercially available probes. We developed a triple staining approach, combining DNA-FISH with RNA-FISH&#160;and immunofluorescence, using peroxidase based signal amplification to accommodate each staining requirement. A major improvement is the ability to obtain, within 10 &#181;m tissue sections, low-background signals that can be imaged at high resolution by confocal microscopy and wide-field conventional epifluorescence. Additionally, the triple staining worked with a wide range of antibodies directed against cellular and viral proteins. The complete protocol takes 2.5 days to accommodate antibody and probe penetration within the tissue.

Detection of the Genome and Transcripts of a Persistent DNA Virus in Neuronal Tissues by Fluorescent In situ Hybridization Combined with Immunostaining

We established a fluorescent in situ hybridization protocol for the detection of a persistent DNA virus genome within tissue sections of animal models. This protocol enables studying infection process by codetection of the viral genome, its RNA products, and viral or cellular proteins within single cells.

Single cell codetection of a gene, its RNA product and cellular regulatory proteins is critical to study gene expression regulation. This is a challenge ...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing.

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing paradigms.

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for maintenance, repair or neurodegeneration in postdevelopmental periods. High throughput analyses have recently revealed that axons have a more dynamic and complex transcriptome than previously expected. These analysis, however have been mostly done in cultured neurons where axons can be isolated from the somato-dendritic compartments. It is virtually impossible to achieve such isolation in whole tissues in vivo. Thus, in order to verify the recruitment of mRNAs and their functional relevance in a whole animal, transcriptome analyses should ideally be combined with techniques that allow the visualization of mRNAs in situ. Recently, novel ISH technologies that detect RNAs at a single-molecule level have been developed. This is especially important when analyzing the subcellular localization of mRNA, since localized RNAs are typically found at low levels. Here we describe two protocols for the detection of axonally-localized mRNAs using a novel ultrasensitive RNA ISH technology. We have combined RNAscope ISH with axonal counterstain using fluorescence immunohistochemistry or histological dyes to verify the recruitment of Atf4 mRNA to axons in vivo in the mature mouse and human brains.

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

RNA in situ hybridization (ISH) enables the visualization of RNAs in cells and tissues. Here we show how combination of RNAscope ISH with immunohistochemistry or histological dyes can be successfully used to detect mRNAs localized to axons in sections of mouse and human brains.

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for ...

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the gold-standard experimental model to study basic neurophysiological mechanisms involved in the formation and maintenance of neuronal cell assemblies. However, in vitro studies have been limited to the recording of the electrophysiological activity generated by bi-dimensional (2D) neural networks. Nonetheless, given the intricate relationship between structure and dynamics, a significant improvement is necessary to investigate the formation and the developing dynamics of three-dimensional (3D) networks. In this work, a novel experimental platform in which 3D hippocampal or cortical networks are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are realized by seeding neurons in a scaffold constituted of glass microbeads (30-40 &#181;m in diameter) on which neurons are able to grow and form complex interconnected 3D assemblies. In this way, it is possible to design engineered 3D networks made up of 5-8 layers with an expected final cell density. The increasing complexity in the morphological organization of the 3D assembly induces an enhancement of the electrophysiological patterns displayed by this type of networks. Compared with the standard 2D networks, where highly stereotyped bursting activity emerges, the 3D structure alters the bursting activity in terms of duration and frequency, as well as it allows observation of more random spiking activity. In this sense, the developed 3D model more closely resembles in vivo neural networks.

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

In this work, a novel experimental model in which 3D neuronal cultures are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are built by seeding neurons in a scaffold made up of glass microbeads on which neurons grow and form interconnected 3D structures.

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the ...

Reliable Identification of Living Dopaminergic Neurons in Midbrain Cultures Using RNA Sequencing and TH-promoter-driven eGFP Expression

In Parkinson&#39;s Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, leading to bradykinesia, rigidity, and tremor. The identification of living dopaminergic neurons in primary Ventral Mesencephalic (VM) cultures using a fluorescent marker provides an alternative way to study the selective vulnerability of these neurons without relying on the immunostaining of fixed cells. Here, we isolate, dissociate, and culture mouse VM neurons for 3 weeks. We then identify dopaminergic neurons in the cultures using eGFP fluorescence (driven by a Tyrosine Hydroxylase (TH) promoter). Individual neurons are harvested into microcentrifuge tubes using glass micropipettes. Next, we lyse the harvested cells, and conduct cDNA synthesis and transposon-mediated &#34;tagmentation&#34; to produce single cell RNA-Seq libraries1,2,3,4,5. After passing a quality-control check, single-cell libraries are sequenced and subsequent analysis is carried out to measure gene expression. We report transcriptome results for individual dopaminergic and GABAergic neurons isolated from midbrain cultures. We report that 100% of the live TH-eGFP cells that were harvested and sequenced were dopaminergic neurons. These techniques will have widespread applications in neuroscience and molecular biology.

In Parkinson&#39;s Disease (PD), Substantia Nigra (SNc) dopaminergic neurons degenerate, leading to motor dysfunction. Here we report a protocol for culturing ventral midbrain neurons from a mouse expressing eGFP driven by a Tyrosine Hydroxylase (TH) promoter sequence, harvesting individual fluorescent neurons from the cultures, and measuring their transcriptome using RNA-seq.

In Parkinson&#39;s Disease (PD) there is widespread neuronal loss throughout the brain with pronounced degeneration of dopaminergic neurons in the SNc, ...

Localization of Odorant Receptor Genes in Locust Antennae by RNA In Situ Hybridization

Insects have evolved sophisticated olfactory reception systems to sense exogenous chemical signals. These chemical signals are transduced by Olfactory Receptor Neurons (ORNs) housed in hair-like structures, called chemosensilla, of the antennae. On the ORNs&#39; membranes, Odorant Receptors (ORs) are believed to be involved in odor coding. Thus, being able to identify genes localized to the ORNs is necessary to recognize OR genes, and provides a fundamental basis for further functional in situ studies. The RNA expression levels of specific ORs in insect antennae are very low, and preserving insect tissue for histology is challenging. Thus, it is difficult to localize an OR to a specific type of sensilla using RNA in situ hybridization. In this paper, a detailed and highly effective RNA in situ hybridization protocol particularly for lowly expressed OR genes of insects, is introduced. In addition, a specific OR gene was identified by conducting double-color fluorescent in situ hybridization experiments using a co-expressing receptor gene, Orco, as a marker.

Localization of Odorant Receptor Genes in Locust Antennae by RNA In Situ Hybridization

This paper describes a detailed and highly effective RNA in situ hybridization protocol particularly for low-level expressed Odorant Receptor (OR) genes, as well as other genes, in insect antennae using digoxigenin (DIG)-labeled or biotin-labeled probes.

Insects have evolved sophisticated olfactory reception systems to sense exogenous chemical signals. These chemical signals are transduced by Olfactory ...

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.

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) ...