Name: single cell multiplex reverse transcription polymerase chain reaction after patch-clamp
Uploaded: 2018-06-20T13:00:00
Description: Watch this Scientific Journal Video about Single Cell Multiplex Reverse Transcription Polymerase Chain Reaction After Patch-clamp at JoVE.com

We thank Dr. Alexandre Mourot for his comments on the manuscript. This work was supported by grants from the Agence Nationale de la Recherche (ANR 2011 MALZ 003 01; ANR-15-CE16-0010 and ANR-17-CE37-0010-03), BLG is supported by fellowship from the Fondation pour la Recherche sur Alzheimer. We thank the animal facility of the IBPS (Paris, France).

All experimental procedures using animals were performed in strict accordance with French regulations (Code Rural R214/87 to R214/130) and conformed to the ethical guidelines of both the European Economic Community (86/609/EEC) and the French National Charter on the ethics of animal experimentation. All protocols were approved by the Charles Darwin ethics committee and submitted to the French Ministry of Education and Research (Approval 2015 061011367540). The IBPS animal facility is accredited by the French authorities ...

Single cell multiplex RT-PCR after patch-clamp can simultaneously and reliably probe the expression of more than 30 genes in electrophysiologically identified cells5. Analyzing gene expression at the single cell level requires highly efficient PCR primers. One of the most limiting steps is collection of the cell&#39;s content. Its efficiency depends on the diameter of the patch pipette tip, which must be as large as possible while matching the cell size. Pipettes with a 1-2 &#181;m open tip diamet...

The cerebral cortex comprises numerous cell types involved in various physiological processes. Their identification and characterization, a prerequisite to the understanding of their specific functions, can be very challenging given the large morphological, physiological, and molecular diversity that characterizes cortical cell types1,2,3,4.
Single-cell multiplex RT-PCR is based on the combination of patch-clamp and RT-PCR techniques. It can probe simultaneously the expression of more than 30 predefined genes in electrophysiologically identified cells5. The inclusion of a neuronal tracer in the recording pipette further allows the morphological characterization of the recorded cells after histochemical revelation6,7,8,9,10. It is a very useful technique for the classification of neuronal types based on multivariate analysis of their phenotypic traits5,9,10,11,12,13,14. Single cell multiplex RT-PCR is also suited to the characterization of non-neuronal cells such as astrocytes15,16,17, and can be virtually applied to every brain structure18,19,20,21,22,23 and cell type, assuming they can be recorded in whole-cell configuration.
This technique is very convenient for the identification of cellular sources and/or targets of transmission systems7,8,15,16,20,21,24,25,26,27,28, especially when specific antibodies are lacking. It relies on patch-clamp recordings from visually identified cells29, and thus also allows the targeting of cells in a specific cellular environment8,15,16. Furthermore since the cytoarchitecture of brain tissue is preserved in brain slices, this approach also enables study of the anatomical relationships of the characterized cells with neuronal and non-neuronal elements7,8,18.
Since this technique is limited by the amount of harvested cytoplasm and by the efficiency of the RT, the detection of mRNA expressed at low copy number can be difficult. Although other approaches based on RNaseq technology allow to analyze the whole transcriptome of single cells3,4,30,31, they need high-throughput expensive sequencers not necessarily available to every laboratory. Since the single cell multiplex RT-PCR technique uses end-point PCR, it only requires widely available thermocyclers. It can be easily developed in laboratories equipped with electrophysiological set-ups and does not require expensive equipment. It can provide, within one day, a qualitative analysis of the expression of a predefined set of genes. Thus, this approach offers an easy access to the molecular characterization of single cells in a rapid manner.

<table>
	<tbody>
		<tr>
			<td>MACAW v.2.0.5</td>
			<td>NCBI</td>
			<td></td>
			<td>Multiple alignement for primer design</td>
		</tr>
		<tr>
			<td>Dithiothreitol</td>
			<td>VWR</td>
			<td>443852A</td>
			<td>RT</td>
		</tr>
		<tr>
			<td>Random primers</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>11034731001</td>
			<td>RT</td>
		</tr>
		<tr>
			<td>dNTPs</td>
			<td>GE Healthcare Life Sciences</td>
			<td>28-4065-52</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>RNasin Ribonuclease Inhibitors</td>
			<td>Promega</td>
			<td>N2511</td>
			<td>RT</td>
		</tr>
		<tr>
			<td>SuperScript II Reverse Transcriptase</td>
			<td>Invitrogen</td>
			<td>18064014</td>
			<td>RT</td>
		</tr>
		<tr>
			<td>Taq DNA Polymerase</td>
			<td>Qiagen</td>
			<td>201205</td>
			<td>PCR</td>
		</tr>
		<tr>
			<td>Mineral Oil</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>M5904-5ML</td>
			<td>PCR</td>
		</tr>
		<tr>
			<td>PCR primers</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td></td>
			<td>PCR / desalted and diluted at 200 &#181;M</td>
		</tr>
		<tr>
			<td>Tubes, 0.5 mL, flat cap</td>
			<td>ThermoFisher Scientific</td>
			<td>AB0350</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>BT10 Series - 10 &#181;L Filter Tip</td>
			<td>Neptune Scientific</td>
			<td>BT10</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>BT20 Series - 20 &#181;L Filter Tip</td>
			<td>Neptune Scientific</td>
			<td>BT20</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>BT200 Series - 200 &#181;L Filter Tip</td>
			<td>Neptune Scientific</td>
			<td>BT200</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>BT1000 Series - 1000 &#181;L Filter Tip</td>
			<td>Neptune Scientific</td>
			<td>BT1000.96</td>
			<td>RT and PCR</td>
		</tr>
		<tr>
			<td>DNA Thermal Cylcer</td>
			<td>Perkin Elmer Cetus</td>
			<td></td>
			<td>PCR</td>
		</tr>
		<tr>
			<td>Ethidium Bromide</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>E1510-10ML</td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>Tris-Borate-EDTA buffer</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>T4415-1L</td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>UltraPure Agarose</td>
			<td>Life Technologies</td>
			<td>16500-500</td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>&#934;X174 DNA-Hae III Digest</td>
			<td>NEB (New England BioLabs)</td>
			<td>N3026S</td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>EDA 290</td>
			<td>Kodak</td>
			<td></td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>Electrophoresis Power supply EPS 3500</td>
			<td>Pharmacia Biotech</td>
			<td></td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>Midi Horizontal Elecrophoresis Unit Model SHU13</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td></td>
			<td>Agarose gel electrophoresis</td>
		</tr>
		<tr>
			<td>Smooth paper with satin appearance</td>
			<td>Fisherbrand</td>
			<td>1748B</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Potassium Hydroxyde</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>60377</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Ethylene glycol-bis(2-aminoethylether)-N,N,N&#8242;,N&#8242;-tetraacetic acid</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>E3889</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>H4034</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Potassium D-gluconate</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>G4500</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Magnesium chloride solution</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>M1028</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>5500 Vapor Pressure Osmometer</td>
			<td>Wescor</td>
			<td></td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Biocytin</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>B4261</td>
			<td>Patch clamp internal solution</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>S5016</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>D-(+)-Glucose monohydrate</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>49159</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>S6191</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>60128</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>31437-M</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Sodium phosphate monobasic</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>S5011</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Magnesium chloride solution</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>63069</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Calcium chloride solution</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>21115</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Kynurenic acid</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>K3375</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Piramal Healthcare UK</td>
			<td></td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>VT 1000S</td>
			<td>Leica Biosystems</td>
			<td>14047235613</td>
			<td>Slice preparation</td>
		</tr>
		<tr>
			<td>Hydrogen peroxide solution</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>H1009</td>
			<td>Patch Clamp set-up cleaning</td>
		</tr>
		<tr>
			<td>Thin Wall Glass Capillaries with filament</td>
			<td>World Precision Instruments</td>
			<td>TW150F-4</td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>PP-83</td>
			<td>Narishige</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>Eppendorf Microloader</td>
			<td>Eppendorf</td>
			<td>5242956003</td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>BX51WI Upright microscope</td>
			<td>Olympus</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>XC-ST70/CE CCD B/W VIDEO CAMERA</td>
			<td>Sony</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>Axopatch 200B Amplifier</td>
			<td>Molecular Devices</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>Digidata 1440</td>
			<td>Molecular Devices</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>pCLAMP 10 software suite</td>
			<td>Molecular Devices</td>
			<td></td>
			<td>Patch Clamp</td>
		</tr>
		<tr>
			<td>10 mL syringe</td>
			<td>Terumo</td>
			<td>SS-10ES</td>
			<td>Expelling</td>
		</tr>
		<tr>
			<td>E Series with Straight Body (Holder)</td>
			<td>Phymep</td>
			<td>64-0997</td>
			<td>Expelling</td>
		</tr>
		<tr>
			<td>Sodium phosphate dibasic</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>S7907</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>Sodium phosphate monobasic</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>S8282</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>P6148</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>X100</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>Gelatin from cold water fish skin</td>
			<td>Sigma-Aldrich (Merck)</td>
			<td>G7041</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>Streptavidin, Alexa Fluor 488 conjugate</td>
			<td>ThermoFisher Scientific</td>
			<td>S11223</td>
			<td>Histochemical revelation</td>
		</tr>
		<tr>
			<td>24-well plate</td>
			<td>Greiner Bio-One</td>
			<td>662160</td>
			<td>Histochemical revelation</td>
		</tr>
	</tbody>
</table>

single cell multiplex reverse transcription polymerase chain reaction after patch-clamp

The cerebral cortex is composed of numerous cell types exhibiting various morphological, physiological, and molecular features. This diversity hampers easy identification and characterization of these cell types, prerequisites to study their specific functions. This article describes the multiplex single cell reverse transcription polymerase chain reaction (RT-PCR) protocol, which allows, after patch-clamp recording in slices, to detect simultaneously the expression of tens of genes in a single cell. This simple method can be implemented with morphological characterization and is widely applicable to determine the phenotypic traits of various cell types and their particular cellular environment, such as in the vicinity of blood vessels. The principle of this protocol is to record a cell with the patch-clamp technique, to harvest and reverse transcribe its cytoplasmic content, and to detect qualitatively the expression of a predefined set of genes by multiplex PCR. It requires a careful design of PCR primers and intracellular patch-clamp solution compatible with RT-PCR. To ensure a selective and reliable transcript detection, this technique also requires appropriate controls from cytoplasm harvesting to amplification steps. Although precautions discussed here must be strictly followed, virtually any electrophysiological laboratory can use the multiplex single cell RT-PCR technique.

A representative validation of multiplex RT-PCR is shown in Figure 3. The protocol was designed to probe simultaneously the expression of 12 different genes. The vesicular glutamate transporter vGluT1 was taken as a positive control for glutamatergic neurons42. The GABA synthesizing enzymes (GAD65 and GAD 67), Neuropeptide Y (NPY), and Somatostatin (SOM) were used as markers of GABAergic interneurons3,</sup...

Watch this Scientific Journal Video about Single Cell Multiplex Reverse Transcription Polymerase Chain Reaction After Patch-clamp at JoVE.com

Single Cell Multiplex Reverse Transcription Polymerase Chain Reaction After Patch-clamp

This protocol describes the critical steps and precautions required to perform single cell multiplex reverse transcription polymerase chain reaction after patch-clamp. This technique is a simple and effective method to analyze the expression profile of a predetermined set of genes from a single cell characterized by patch-clamp recordings.

The cerebral cortex is composed of numerous cell types exhibiting various morphological, physiological, and molecular features. This diversity hampers ...

This method can help answer key questions in neuroscience research, such as characterizing neuro population or identifying sources and targets of transmission systems. The main advantage of this technique is that it allows to determine the expression profile of a pre-selected set of genes from a single cell quickly and easily. So this method can provide insight into the random diversity mouse.It can also be applied to other cell types, such as astrocytes and in many animal models. This demonstration of this method is critical as the arresting and aspiring steps can be difficult to learn because the data needs a quantity of cytoplasm to be analyzed. Before sectioning, prepare a dissection kit containing surgical scissors, fine iris scissors, two spatulas, forceps, a disc of paper filter, and cyanoacrylate glue.Then saturate the ice cold cutting solution with carbogyn and cool down the cutting chamber at negative 20 degrees Celsius. Next, remove the animal's scalp and open the skull. Extract the brain carefully and place it into a small beaker filled with carbogenated ice cold cutting solution.Afterward, remove the cutting chamber from negative 20 degrees Celsius and remove the moisture with a paper towel. Carefully dissect the brain to isolate the region of interest. Glue it on to the cutting chamber and add the carboginated, ice cold cutting solution.Using a vibratone, section 300 micrometer thick slices. Transfer the slices to a resting chamber filled with oxygenated cutting solution at room temperature and allow them to recover for at least 30 minutes. For single cell RT-PCR and the targeted cell characterization, limit whole cell recording to no longer than 20 minutes in order to preserve the mRNAse.At the end of the recording prepare a 500 microliter PCR tube filled with two microliters of 5xRT mix and 0.5 microliters of 20xDTT. Spin it and store it on ice. Then harvest the cell's cytoplasm by applying a gentle negative pressure.Monitor and control the cell's content from getting into the pipette while maintaining a tight seal and avoid collecting the nucleus if some genes are considered. In the case of gene, it is essential to avoid the collection of the nucleus and to include a set of primers aimed at amplifying gDNA to prep for general contamination. If the nucleus is getting close to the tip of the pipette, release the negative pressure and move the pipette away.Ensure that the tight seal is preserved and restart the collection of the cytoplasm at the new pipette location. Next, withdraw the pipette gently to form an outside out patch to limit contamination by the extracellular debris and to favor the closure of the cell membrane for subsequent histo-chemical analysis. Keep in mind that nubs, micro-manipulators, computer keyboard or computer mouse, are proton charged sources of rnase contamination.If they have been touched during the recording, change the gloves. Subsequently, attach the pipette to the expeller, and expel its content into the PCR tube by applying positive pressure. Break the tip of the pipette into the PCR tube to help the collection of its content.Then, briefly centrifuge the tube add 0.5 microliters of RNAse inhibitor and 0.5 microlitres of RTAse. Mix gently, centrifuge again, and incubate overnight at 37 degrees Celsius. The next day, spin the tube, and store it at negative 80 degrees Celsius for up to several months.Until PCR analysis and performing the first amplication step. To validate PCR, mix and dilute a primer pair, add one micromolar with the pipette dedicated to the single cell RTPCR. Set the thermo cycler for three minutes at 95 degrees Celsius, run 40 cycles followed by a final elongation step at 72 degrees Celsius for five minutes.To minimize the formation of primer dimers, perform a hot start by placing the PCR tubes in the thermo cycler preheated at 95 degrees Celsius. After 30 seconds, quickly expel 20 microliters of the primer mix on top of the oil. Once the primer pair has been validated, test it with the multiplex protocol.Mix and dilute the external primer together at one micromolar. Store the multiplex primer mix at negative 20 degrees Celsius for up to several weeks. Next, prepare a pre-mix and place it on ice.Flick the PCR tube and spin it and add two drops of mineral oil. After three minutes at 95 degrees Celsius, run 20 PCR cycles. Perform a hot start as described with 20 microlitres of multiplex primer mix.Then, prepare a number of PCR tubes identical to the number of genes being analyzed. Prepare a pre mix using one microliter of the first PCR product per gene as template. Adjust all the volumes according to the number of genes to analyze and consider using 10%of extra volume to compensate for pipetting errors.Shake gently, spin the tube and dispatch 80 microliters of premix into each PCR tube. Add two drops of mineral oil per tube without touching the wall or the cap of the tubes. Run 35 PCR cycles then perform a hot start by expelling 20 microliters of internal primer mix.Analyze the second PCR projects by aragose gel electrophoresis. A layer five pyramidal neuron was visually identified by it's large soma and a prominent apical dendrite. Pull-cell recording revealed typical electro-physiological properties of layer five regular spiking neurons with a low input resistance, long lasting action potentials, and pronounced spike-frequency adaptation.The molecular analysis of this neuron revealed the expression of vGluT1, confirming its glutamitergic phenotype. This neuron also expressed somatostatin and the ATP1-alpha-1 and three sub-units of the sodium-potassium ATPAs. Biocytin labeling of the recorded neurons, confirmed a pyramidal morphology.As expected from the glutamitergic neurons, the molecular analysis of 26 layer-five pyramidal cells, revealed the expression of vGluT1 but neither of the two GADs. Once technique can be done within two days, if it's preformed properly. While attempting this procedure, it's important to remember to be very careful to avoid contaminations.After watching this video, you should have a good understanding of how to probe the expression of 10s of genes simultaneously from single cells characterized by patch clumps according to brain slices, after cytoplasm harvesting, reverse transcription, and hot-start PCRs. Don't forget that working with Ethidium bromide can be extremely hazardous and precautions such as wearing gloves and lab coats should always be taken while performing this procedure.

single-cell-multiplex-reverse-transcription-polymerase-chain-reaction

Research

JoVE Journal

Neuroscience

Culturing and Electrophysiology of Cells on NRCC Patch-clamp Chips

Due to its exquisite sensitivity and the ability to monitor and control individual cells at the level of ion channels, patch-clamping is the gold standard of electrophysiology applied to disease models and pharmaceutical screens alike 1. The method traditionally involves gently contacting a cell with a glass pipette filled by a physiological solution in order to isolate a patch of the membrane under its apex 2. An electrode inserted in the pipette captures ion-channel activity within the membrane patch or, when ruptured, for the whole cell. In the last decade, patch-clamp chips have been proposed as an alternative 3, 4: a suspended film separates the physiological medium from the culture medium, and an aperture microfabricated in the film replaces the apex of the pipette. Patch-clamp chips have been integrated in automated systems and commercialized for high-throughput screening 5. To increase throughput, they include the fluidic delivery of cells from suspension, their positioning on the aperture by suction, and automated routines to detect cell-to-probe seals and enter into whole cell mode. We have reported on the fabrication of a silicon patch-clamp chip with optimized impedance and orifice shape that permits the high-quality recording of action potentials in cultured snail neurons 6; recently, we have also reported progress towards interrogating mammalian neurons 7. Our patch-clamp chips are fabricated at the Canadian Photonics Fabrication Centre 8, a commercial foundry, and are available in large series. We are eager to engage in collaborations with electrophysiologists to validate the use of the NRCC technology in different models. The chips are used according to the general scheme represented in Figure 1: the silicon chip is at the bottom of a Plexiglas culture vial and the back of the aperture is connected to a subterranean channel fitted with tubes at either end of the package. Cells are cultured in the vial and the cell on top of the probe is monitored by a measuring electrode inserted in the channel.The two outside fluidic ports facilitate solution exchange with minimal disturbance to the cell; this is an advantage compared to glass pipettes for intracellular perfusion.
<img alt="Figure 1" src="/files/ftp_upload/3288/3288fig1.jpg" />
Figure 1. Principle of measurement using the NRCC patch-clamp chip
We detail here the protocols to sterilize and prime the chips, load them with medium, plate them with cells, and finally use them for electrophysiological recordings.

We show how planar patch-clamp chips fabricated at the National Research Council of Canada are sterilized, primed, loaded with medium, plated with cells, and used for electrophysiological recordings.

Due to its exquisite sensitivity and the ability to monitor and control individual cells at the level of ion channels, patch-clamping is the gold standard ...

Patch-clamp Capacitance Measurements and Ca2+ Imaging at Single Nerve Terminals in Retinal Slices

Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate retina. Two classes of retinal neurons, photoreceptors and bipolar cells, accomplish this by using ribbon-type active zones, which enable sustained and high-throughput neurotransmitter release over long time periods. ON-type mixed bipolar cell (Mb) terminals in the goldfish retina, which depolarize to light stimuli and receive mixed rod and cone photoreceptor input, are suitable for the study of ribbon-type synapses both due to their large size (~10-12 &mu;m diameter) and to their numerous lateral and reciprocal synaptic connections with amacrine cell dendrites. Direct access to Mb bipolar cell terminals in goldfish retinal slices with the patch-clamp technique allows the measurement of presynaptic Ca2+ currents, membrane capacitance changes, and reciprocal synaptic feedback inhibition mediated by GABAA and GABAC receptors expressed on the terminals. Presynaptic membrane capacitance measurements of exocytosis allow one to study the short-term plasticity of excitatory neurotransmitter release 14,15. In addition, short-term and long-term plasticity of inhibitory neurotransmitter release from amacrine cells can also be investigated by recordings of reciprocal feedback inhibition arriving at the Mb terminal 21. Over short periods of time (e.g. ~10 s), GABAergic reciprocal feedback inhibition from amacrine cells undergoes paired-pulse depression via GABA vesicle pool depletion 11. The synaptic dynamics of retinal microcircuits in the inner plexiform layer of the retina can thus be directly studied.
The brain-slice technique was introduced more than 40 years ago but is still very useful for the investigation of the electrical properties of neurons, both at the single cell soma, single dendrite or axon, and microcircuit synaptic level 19. Tissues that are too small to be glued directly onto the slicing chamber are often first embedded in agar (or placed onto a filter paper) and then sliced 20, 23, 18, 9. In this video, we employ the pre-embedding agar technique using goldfish retina. Some of the giant bipolar cell terminals in our slices of goldfish retina are axotomized (axon-cut) during the slicing procedure. This allows us to isolate single presynaptic nerve terminal inputs, because recording from axotomized terminals excludes the signals from the soma-dendritic compartment. Alternatively, one can also record from intact Mb bipolar cells, by recording from terminals attached to axons that have not been cut during the slicing procedure. Overall, use of this experimental protocol will aid in studies of retinal synaptic physiology, microcircuit functional analysis, and synaptic transmission at ribbon synapses.

Patch-clamp Capacitance Measurements and Ca2+ Imaging at Single Nerve Terminals in Retinal Slices

Here we describe a protocol for the preparation of agar-embedded retinal slices that are suitable for electrophysiology and Ca2+ imaging. This method allows one to study ribbon-type synapses in retinal microcircuits using direct patch-clamp recordings of single presynaptic nerve terminals.

Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate ...

Whole Cell Patch Clamp for Investigating the Mechanisms of Infrared Neural Stimulation

It has been demonstrated in recent years that pulsed, infrared laser light can be used to elicit electrical responses in neural tissue, independent of any further modification of the target tissue. Infrared neural stimulation has been reported in a variety of peripheral and sensory neural tissue in vivo, with particular interest shown in stimulation of neurons in the auditory nerve. However, while INS has been shown to work in these settings, the mechanism (or mechanisms) by which infrared light causes neural excitation is currently not well understood. The protocol presented here describes a whole cell patch clamp method designed to facilitate the investigation of infrared neural stimulation in cultured primary auditory neurons. By thoroughly characterizing the response of these cells to infrared laser illumination in vitro under controlled conditions, it may be possible to gain an improved understanding of the fundamental physical and biochemical processes underlying infrared neural stimulation.

Infrared nerve stimulation has been proposed as an alternative to electrical stimulation in a range of nerve types, including those associated with the auditory system. This protocol describes a patch clamp method for studying the mechanism of infrared nerve stimulation in a culture of primary auditory neurons.

It has been  demonstrated in recent years that pulsed, infrared laser light can be used to  elicit electrical responses in neural tissue, independent of ...

Patch Clamp Recordings from Embryonic Zebrafish Mauthner Cells

Mauthner cells (M-cells) are large reticulospinal neurons located in the hindbrain of teleost fish. They are key neurons involved in a characteristic behavior known as the C-start or escape response that occurs when the organism perceives a threat. The M-cell has been extensively studied in adult goldfish where it has been shown to receive a wide range of excitatory, inhibitory and neuromodulatory signals1. We have been examining M-cell activity in embryonic zebrafish in order to study aspects of synaptic development in a vertebrate preparation. In the late 1990s Ali and colleagues developed a preparation for patch clamp recording from M-cells in zebrafish embryos, in which the CNS was largely intact2,3,4. The objective at that time was to record synaptic activity from hindbrain neurons, spinal cord neurons and trunk skeletal muscle while maintaining functional synaptic connections within an intact brain-spinal cord preparation. This preparation is still used in our laboratory today. To examine the mechanisms underlying developmental synaptic plasticity, we record excitatory (AMPA and NMDA-mediated)5,6 and inhibitory (GABA and glycine) synaptic currents from developing M-cells. Importantly, this unique preparation allows us to return to the same cell (M-cell) from preparation to preparation to carefully examine synaptic plasticity and neuro-development in an embryonic organism. The benefits provided by this preparation include 1) intact, functional synaptic connections onto the M-cell, 2) relatively inexpensive preparations, 3) a large supply of readily available embryos 4) the ability to return to the same cell type (i.e. M-cell) in every preparation, so that synaptic development at the level of an individual cell can be examined from fish to fish, and 5) imaging of whole preparations due to the transparent nature of the embryos.

We have developed an intact brain-spinal cord preparation to record and monitor electrical activity via patch clamp recording from the Mauthner neurons and other reticulospinal cells in zebrafish embryos. Thus, we are able to record excitatory and inhibitory synaptic currents, voltage-gated channel activity and action potentials from key neurons in a developing embryo.

Mauthner cells (M-cells) are large  reticulospinal neurons located in the hindbrain of teleost fish. They are key  neurons involved in a characteristic ...

A Computer-assisted Multi-electrode Patch-clamp System

The patch-clamp technique is today the most well-established method for recording electrical activity from individual neurons or their subcellular compartments. Nevertheless, achieving stable recordings, even from individual cells, remains a time-consuming procedure of considerable complexity. Automation of many steps in conjunction with efficient information display can greatly assist experimentalists in performing a larger number of recordings with greater reliability and in less time. In order to achieve large-scale recordings we concluded the most efficient approach is not to fully automatize the process but to simplify the experimental steps and reduce the chances of human error while efficiently incorporating the experimenter's experience and visual feedback. With these goals in mind we developed a computer-assisted system which centralizes all the controls necessary for a multi-electrode patch-clamp experiment in a single interface, a commercially available wireless gamepad, while displaying experiment related information and guidance cues on the computer screen. Here we describe the different components of the system which allowed us to reduce the time required for achieving the recording configuration and substantially increase the chances of successfully recording large numbers of neurons simultaneously.

Multi-electrode patch-clamp recordings constitute a complex task. Here we show how, by automating of many of the experimental steps, it is possible to accelerate the process leading to qualitative improvement in performance and number of recordings.

The patch-clamp technique is today the most  well-established method for recording electrical activity from individual  neurons or their subcellular ...

Whole-cell Patch-clamp Recordings from Morphologically- and Neurochemically-identified Hippocampal Interneurons

GABAergic inhibitory interneurons play a central role within neuronal circuits of the brain. Interneurons comprise a small subset of the neuronal population (10-20%), but show a high level of physiological, morphological, and neurochemical heterogeneity, reflecting their diverse functions. Therefore, investigation of interneurons provides important insights into the organization principles and function of neuronal circuits. This, however, requires an integrated physiological and neuroanatomical approach for the selection and identification of individual interneuron types. Whole-cell patch-clamp recording from acute brain slices of transgenic animals, expressing fluorescent proteins under the promoters of interneuron-specific markers, provides an efficient method to target and electrophysiologically characterize intrinsic and synaptic properties of specific interneuron types. Combined with intracellular dye labeling, this approach can be extended with post-hoc morphological and immunocytochemical analysis, enabling systematic identification of recorded neurons. These methods can be tailored to suit a broad range of scientific questions regarding functional properties of diverse types of cortical neurons.

Cortical networks are controlled by a small, but diverse set of inhibitory interneurons. Functional investigation of interneurons therefore requires targeted recording and rigorous identification. Described here is a combined approach involving whole-cell recordings from single or synaptically-coupled pairs of neurons with intracellular labeling, post-hoc morphological and immunocytochemical analysis.

GABAergic inhibitory interneurons play a central role within neuronal circuits of the brain. Interneurons comprise a small subset of the neuronal ...

Recording Light-evoked Postsynaptic Responses in Neurons in Dark-adapted, Mouse Retinal Slice Preparations Using Patch Clamp Techniques

The retina is the gateway to the visual system. To understand visual signal processing mechanisms, we investigate retinal neural network functions. Retinal neurons in the network comprise of numerous subtypes. More than 10 subtypes of bipolar cells, ganglion cells, and amacrine cells have been identified by morphological studies. Multiple subtypes of retinal neurons are thought to encode distinct features of visual signaling, such as motion and color, and form multiple neural pathways. However, the functional roles of each neuron in visual signal processing are not fully understood. The patch clamp method is useful to address this fundamental question. Here, a protocol to record light-evoked synaptic responses in mouse retinal neurons using patch clamp recordings in dark-adapted conditions is provided. The mouse eyes are dark-adapted O/N, and retinal slice preparations are dissected in a dark room using infrared illumination and viewers. Infrared light does not activate mouse photoreceptors and thus preserves their light responsiveness. Patch clamp is used to record light-evoked responses in retinal neurons. A fluorescent dye is injected during recordings to characterize neuronal morphological subtypes. This procedure enables us to determine the physiological functions of each neuron in the mouse retina.

We will demonstrate how to prepare retinal slices from the mouse eye and record light responses in retinal neurons. The entire procedure is conducted in dark-adapted conditions.

The retina is the gateway to the visual system. To understand visual signal processing mechanisms, we investigate retinal neural network functions. ...

Whole-cell Patch-clamp Recordings in Brain Slices

Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the&#160;electrical properties of a substantial part of the neuron. In this configuration, the micropipette is in tight contact with the cell membrane, which prevents current leakage and thereby provides more accurate ionic current measurements than the previously used intracellular sharp electrode recording method. Classically, whole-cell recording can be performed on neurons in various types of preparations, including cell culture models, dissociated neurons, neurons in brain slices, and in intact anesthetized or awake animals. In summary, this technique has immensely contributed to the understanding of passive and active biophysical properties of excitable cells. A major advantage of this technique is that it provides information on how specific manipulations (e.g., pharmacological, experimenter-induced plasticity) may alter specific neuronal functions or channels in real-time. Additionally, significant opening of the plasma membrane allows the internal pipette solution to freely diffuse into the cytoplasm, providing means for introducing drugs, e.g., agonists or antagonists of specific intracellular proteins, and manipulating these targets without altering their functions in neighboring cells. This article will focus on whole-cell recording performed on neurons in brain slices,&#160;a preparation that has the advantage of recording neurons in relatively well preserved brain circuits, i.e., in a physiologically relevant context. In particular,&#160;when combined with appropriate pharmacology, this technique is a powerful tool allowing identification of specific neuroadaptations that occurred following any type of experiences, such as learning, exposure to drugs of abuse, and stress. In summary, whole-cell patch-clamp recordings in brain slices provide means to measure in ex vivo preparation long-lasting changes in neuronal functions that have developed in intact awake animals.

This protocol describes basic procedural steps for performing whole-cell patch-clamp recordings. This technique allows the study of&#160;the electrical behavior of neurons, and when performed in brain slices, allows the assessment of various neuronal functions from neurons that are still integrated in relatively well preserved brain circuits.

Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the&#160;electrical properties of a substantial part of the ...

Whole-cell Patch-clamp Recordings for Electrophysiological Determination of Ion Selectivity in Channelrhodopsins

Over the past decade, channelrhodopsins became indispensable in neuroscientific research where they are used as tools to non-invasively manipulate electrical processes in target cells. In this context, ion selectivity of a channelrhodopsin is of particular importance. This article describes the investigation of chloride selectivity for a recently identified anion-conducting channelrhodopsin of Proteomonas sulcata via electrophysiological patch-clamp recordings on HEK293 cells. The experimental procedure for measuring light-gated photocurrents demands a fast switchable &#8211; ideally monochromatic &#8211; light source coupled into the microscope of an otherwise conventional patch-clamp setup. Preparative procedures prior to the experiment are outlined involving preparation of buffered solutions, considerations on liquid junction potentials, seeding and transfection of cells, and pulling of patch pipettes. The actual recording of current-voltage relations to determine the reversal potentials for different chloride concentrations takes place 24 h to 48 h after transfection. Finally, electrophysiological data are analyzed with respect to theoretical considerations of chloride conduction.

This article describes how the ion selectivity of channelrhodopsin is determined with electrophysiological whole-cell patch-clamp recordings using HEK293 cells. Here, the experimental procedure for investigating chloride selectivity of an anion-selective channelrhodopsin is demonstrated. However, the procedure is transferable to other channelrhodopsins of distinct selectivity.

Over the past decade, channelrhodopsins became indispensable in neuroscientific research where they are used as tools to non-invasively manipulate ...

Slice Patch Clamp Technique for Analyzing Learning-Induced Plasticity

The slice patch clamp technique is a powerful tool for investigating learning-induced neural plasticity in specific brain regions. To analyze motor-learning induced plasticity, we trained rats using an accelerated rotor rod task. Rats performed the task 10 times at 30-s intervals for 1 or 2 days. Performance was significantly improved on the training days compared to the first trial. We then prepared acute brain slices of the primary motor cortex (M1) in untrained and trained rats. Current-clamp analysis showed dynamic changes in resting membrane potential, spike threshold, afterhyperpolarization, and membrane resistance in layer II/III pyramidal neurons. Current injection induced many more spikes in 2-day trained rats than in untrained controls.
To analyze contextual-learning induced plasticity, we trained rats using an inhibitory avoidance (IA) task. After experiencing foot-shock in the dark side of a box, the rats learned to avoid it, staying in the lighted side. We prepared acute hippocampal slices from untrained, IA-trained, unpaired, and walk-through rats. Voltage-clamp analysis was used to sequentially record miniature excitatory and inhibitory postsynaptic currents (mEPSCs and mIPSCs) from the same CA1 neuron. We found different mean mEPSC and mIPSC amplitudes in each CA1 neuron, suggesting that each neuron had different postsynaptic strengths at its excitatory and inhibitory synapses. Moreover, compared with untrained controls, IA-trained rats had higher mEPSC and mIPSC amplitudes, with broad diversity. These results suggested that contextual learning creates postsynaptic diversity in both excitatory and inhibitory synapses at each CA1 neuron.
AMPA or GABAA receptors seemed to mediate the postsynaptic currents, since bath treatment with CNQX or bicuculline blocked the mEPSC or mIPSC events, respectively. This technique can be used to study different types of learning in other regions, such as the sensory cortex and amygdala.

The slice patch clamp technique is an effective method for analyzing learning-induced changes in the intrinsic properties and plasticity of excitatory or inhibitory synapses.