Name: whole-cell currents induced by puff application of gaba in brain slices
Uploaded: 2017-10-12T14:00:00
Description: Watch this Scientific Journal Video about Whole-cell Currents Induced by Puff Application of GABA in Brain Slices at JoVE.com

The authors would like to thank the following organizations: National Natural Science Foundation of China (31171018, 31171355), the Science and Technology Division of Guangdong (2013KJCX0054), the Natural Science Foundation of Guangdong Province (2014A030313418, 2014A030313440), and Guangzhou Science and Technology Bureau (201607010320).

Animal housing and all animal experiments were conducted in accordance with procedures approved by the Ethics Committee for animal research at South China Normal University, according to the Guidelines for Animal Care established by the National Institute of Health.
1. Preparation of Solutions
<ol>
	<li>Prepare 500 mL of standard artificial cerebrospinal fluid (ACSF) containing the components described in our published work7 as listed in Table 1.
	<ol>
		<li>Use clean gla...

<ol>
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Puff application is widely used to evaluate postsynaptic receptor function3,4,7, but requires precise control in each experiment. We describe here a procedure involving whole-cell patch clamping, which demonstrates GABA-puff induced IPSCs (i.e., eIPSCs) in prefrontal cortical brain slices. The resistance of the recording electrode is about 5 M&#937;, while the tip diameter of puff micropipettes is about 2-5 &#181;m. Puff pressur...

The patch-clamp technique, a primary tool for investigating electrical signals in neurons, was developed in the 1970s1,2. A major advantage of this technique is that it provides knowledge on how specific treatments (e.g., pharmacological) may alter neuronal functions or channels in real time3. Pharmacological evaluation of neuronal function during whole-cell recording in a brain slice requires the application of drugs, such as agonists or antagonists of specific receptors, to the neurons being recorded. This method allows the identification of neuronal alterations that occur following application of a specific drug, thus leading to a better understanding of the physiological and pathological properties of the neurons4. Although pharmacological administration can be conducted via either perfusion5 or puff6, the latter is the superior technique. In particular: (i) puff application rapidly increases drug concentration around the recorded neuron to a level such that desensitization of the membrane receptors is prevented; (ii) the volume of drug puffed is extremely low, so that there is little effect on the bath solution, which therefore reduces any undesirable effects of the administered chemicals on brain slices; (iii) the puff protocol can be set and saved, making the experiment very precisely reproducible; (iv) puff application represents economical use of agonists/antagonists, particularly where such reagents are expensive or difficult to obtain.
Here, we will focus on recording whole-cell currents induced by puffing GABA in acutely prepared brain slices, a preparation that has the advantage of relatively well-preserved brain circuits. How we conduct puff-induced inhibitory currents7 will be described in this article. By using cesium (Cs+)-based internal solutions, and holding the neurons at 0 mV, we will introduce GABA-puff evoked inhibitory postsynaptic currents (eIPSCs) with appropriate technical details. Using a mouse model of depression induced by lipopolysaccharide (LPS) injection8, we show that the eIPSC amplitude evoked by a GABA puff is significantly reduced in slices of LPS-injected mice compared to vehicle controls. Our intention is that this article should show how the puff technique is widely applicable to studies aimed at evaluating the effect of any chemicals, compounds or drugs on neuronal activities in brain slices.

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			<td class="xl20" height="40" style="width:161pt;height:30.0pt" width="214">Picospritzer &#8546;</td>
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			Picoliter Volumes in Cell Research</td>
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			<td class="xl20" height="40" style="width:161pt;height:30.0pt" width="214">Razor blade</td>
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			<td class="xl20" height="40" style="width:161pt;height:30.0pt" width="214">Video monitor</td>
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			<td class="xl18" height="40" style="width:161pt;height:30.0pt" width="214">502 Glue</td>
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			<td class="xl18" style="width:155pt" width="206">7146</td>
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			<td class="xl20" height="40" style="width:161pt;height:30.0pt" width="214">Peristaltic pump</td>
			<td class="xl20" style="width:140pt" width="187">Shanghai JIA PENG Corporation</td>
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			<td class="xl20" height="40" style="width:161pt;height:30.0pt" width="214">Video Camera</td>
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			<td class="xl18" style="width:155pt" width="206">30-0138A1</td>
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whole-cell currents induced by puff application of gaba in brain slices

Pharmacological administration is commonly used when conducting whole-cell patch-clamp recording in brain slices. One of the best methods of drug application during electrophysiological recording is the puff technique, which can be used to study the effect of pharmacological reagents on neuronal activities in brain slices. The greatest advantage of puff application is that the drug concentration around the recording site increases rapidly, thus preventing desensitization of membrane receptors. Successful use of puff application involves careful attention to the following elements: the concentration of the drug, the parameters of the puff micropipette, the distance between the tip of a puff micropipette and the neuron recorded, and the duration and pressure driving the puff (pounds per square inch, psi). This article describes a step-by-step procedure for recording whole-cell currents induced by puffing gamma-aminobutyric acid (GABA) onto a neuron of a prefrontal cortical slice. Notably, the same procedure can be applied with minor modifications to other brain areas such as the hippocampus and the striatum, and to different preparations, such as cell cultures.

The puff technique allows researchers to study the effect of drugs on particular receptors on the surface of a given neuron. In this article, we focus on currents mediated by GABA receptors. Figure 1 shows the puff and recording micropipettes. To eliminate any effect on recorded neurons of the physical pressure generated by the puff, ACSF and sucrose puffs (Figure 2A) are used as controls. The response induced by...

Watch this Scientific Journal Video about Whole-cell Currents Induced by Puff Application of GABA in Brain Slices at JoVE.com

Whole-cell Currents Induced by Puff Application of GABA in Brain Slices

We describe the puff technique, by which pharmacological reagents can be administered during whole-cell patch-clamp recording, and highlight various aspects of the features that are crucial for its success.

Pharmacological administration is commonly used when conducting whole-cell patch-clamp recording in brain slices. One of the best methods of drug ...

The overall goal of this puff technique is to conduct the pharmacological administration in whole-cell patch-clamp recording. This method can help answer key questions in the electrophysiology field, such as pharmacological administration. The main advantage of this technique is that the drug concentration around the recording site increases rapidly, thus preventing the membrane receptors from desensitization.Generally, individual new to this method will struggle because the preparation of acute prefrontal cortex slice and the position of puff micropipette are relatively difficult. To begin this procedure, crush the frozen cutting solution to obtain a slush. Keep the slushy solution on ice, and bubble it with 95%oxygen, 5%carbon dioxide.Next, place the dissected head into a beaker filled with ice-cold cutting solution, and take it out after a few seconds. Cut the skull along the midline in a caudal-rostral direction with fine scissors, and remove the lateral skull portions. Then, remove the brain with a fine spatula, and drop it into the ice-cold cutting solution.Afterward, place the brain on the lid of a nine-centimeter Petri dish filled with ice. Rinse the brain with ice-cold cutting solution. Then, cut off the cerebellum and olfactory bulb with a razor blade.Subsequently, apply cyanoacrylate glue to the Vibratome specimen holder. Carefully place the brain block on the drop of glue, rostral side up, and immediately immerse it in the ice-cold cutting solution. Adjust the blade holder to an angle of 15 degrees with reference to the horizontal plane.Section the brain tissues into 350 micron coronal slices. Then, transfer the slides into the recovery chamber filled with ACSF, and incubate them for one hour with constant bubbling of 95%oxygen, 5%carbon dioxide. In our experiment, the preparation of acute prefrontal cortex slice is also critical in the procedure.A healthy brain slice means active neurons that can be patched tightly. In this procedure, make glass borosilicate micropipettes for use as recording electrodes or puff micropipettes. For recording electrodes, tip resistances are in the range of four to six megaohm, while puff micropipettes have tip diameters in the range of two to five micrometers.Add sodion channel blocker to ACSF to block fast sodion channel and thus action potentials, and maintain a constant flow rate of this solution of two to three milliliter per minute in the recording chamber. Bubble the ACSF with 95%oxygen, 5%carbon dioxide constantly to ensure the viability of the slices. Transfer a brain slice to the recording chamber, using a Pasteur pipette with its fine tip cut to fit the size of the slice.Next, place a platinum slice anchor above the slice to hold it on the platform. After that, fill the recording micropipettes with internal solution, and fill the puff micropipettes with GABA at 10 micromolar, 50 micromolar, and 100 micromolar, or ACSF as vehicle control. To prevent blockage with debris, apply slight positive pressure using a one-milliliter syringe before immersing the recording electrode in the ACSF.Under a microscope, position the recording electrode and puff micropipette so that the tips appear in the center of the monitor. Then, identify a target neuron. Adjust the microscope focus while gradually lowering the puff micropipette, and place it above the recording neuron at an angle of 45 degrees.Keep the distance between the tip of the puff micropipette and the target neuron in the range of 20 to 40 micrometers. Slowly and carefully approach the neuron with the recording electrode, and then release the positive pressure. Apply a weak and brief suction through the tubing connected to the electrode holder to create a gigaohm seal.Maintain the voltage at zero millivolts. After the formation of the gigaohm seal, compensate the fast and slow capacitance manually or automatically. Then, apply a brief and strong suction through the tubing to break into the whole-cell mode.Subsequently, record evoked IPSC currents in voltage clamp mode. Deliver single or paired GABA puffs through the puff micropipette controlled by a Master-8 voltage-step generator. Change the puff duration to obtain the best evoked IPSC currents results, and measure the evoked IPSC currents in the LPS-induced depression model.Shown here, are the sample IPSCs induced by 10, 50, and 100 micromolar GABA. And here are the puff duration response curves. The repetitive currents evoked by GABA at 50 micromolar puffs at interpuff intervals of one, two, or three seconds are shown here.One mastered, this technique can be done in two hours if it is performed properly. While attempting this procedure, it's important to remember to obtain healthy brain slices. After its development, this technique paved the way for researchers in the field of pharmacological administration to explore the effect of drug in electrophysiology.After watching this video, you should have a good understanding of how to conduct the pharmacological administration in whole-cell patch-clamp recording. Don't forget that working with TTX can be extremely hazardous and precautions, such as wearing gloves, should always be taken while performing this procedure.

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