This study was supported by the S&#227;o Paulo Research Foundation [FAPESP grant numbers: 2021/11551-4 (JNS), 2015/20198-5 (TTZ), 2019/21707/1 (RF); and by the Coordena&#231;&#227;o de Aperfei&#231;oamento de Pessoal de N&#237;vel Superior (CAPES) - Finance Code 001&#34; (HRV).

All animal procedures were approved by the Institute of Biomedical Sciences Animals Ethics Committee at the University of S&#227;o Paulo and were performed according to the ethical guidelines adopted by the Brazilian College of Animal Experimentation.
1. Preparation of solutions
<ol>
	<li>Preparation of internal solution 
	NOTE: The internal solution fills the patch-clamp micropipette and will contact the cell&#39;s interior (see an example in Figure 2). Internal solutions may vary depending on the type of activity to be measured33.
	<ol>
		<li>Choose the internal solution considering its experimental purpose and the appropriate record type. To record membrane potential in the current-clamp mode, use the internal solution composed of 120 mM K-gluconate, 1 mM NaCl, 5 mM EGTA, 10 mM HEPES, 1 mM MgCl2, 1 mM CaCl2, 3 mM KOH, 10 mM KCl, and 4 mM (Mg)-ATP. Weigh all the salts according to the desired final volume, as given in Table 1.</li>
		<li>Use enough deionized water to reach 90% of the final volume of the solution. This volume will ensure enough space to adjust the pH and osmolarity.</li>
		<li>After adding and mixing all the ingredients thoroughly, adjust the pH to 7.2-7.3 with 5 M KOH using a pH meter. Use an osmometer to check the osmolarity, which should be around 275-280 mOsm (adjust, if necessary, down only).</li>
		<li>Prepare the internal solution in advance and store at 8 &#176;C. Add the ATP on the day of the experiment. Store the ATP-containing internal solution at -20 &#176;C (1 mL aliquots) for 3-4 months.</li>
	</ol>
	</li>
	<li>Preparation of slicing solution
	<ol>
		<li>Prepare slicing solution containing 238 mM sucrose, 2.5 mM KCl, 26 mM NaHCO3, 1.0 mM NaH2PO4, 10 mM glucose, 1.0 mM CaCl2, and 5.0 mM MgCl2. Weigh all the salts according to the desired final volume, as shown in Table 2. The exact volume of this solution to be prepared will depend on the cutting chamber&#39;s size.</li>
		<li>While mixing all the salts in deionized water, constantly saturate with carbogen (95% O2 and 5% CO2). Attach polyethylene tubing (1.57 mm outer diameter [OD] x 1.14 mm inner diameter [ID]) to a carbogen cylinder to supply carbogen to the slicing solution. Hold the open end of the tube inside the beaker containing the slicing solution.</li>
		<li>After mixing all the ingredients well, adjust the pH to 7.3 with 10% nitric acid using a pH meter. Use an osmometer to check the osmolarity, which should be 290-295 mOsm (adjust, if necessary, down only). Afterward, cool the solution to 0-2 &#176;C.</li>
	</ol>
	</li>
	<li>Prepare aCSF solution for recordings
	<ol>
		<li>Prepare artificial cerebrospinal spinal fluid (aCSF) solution for recordings containing 124 mM NaCl, 2.8 mM KCl, 26 mM NaHCO3, 1.25 mM NaH2PO4, 1.2 mM MgSO4, 5 mM glucose, and 2.5 mM CaCl2. Weigh&#160;all the salts according to the desired final volume, given in Table 3.</li>
		<li>While mixing all the salts in deionized water, constantly saturate with carbogen (95% O2 and 5% CO2), as described in step 1.2.2.</li>
		<li>After adding and mixing all the ingredients, adjust the pH to 7.3 (10% nitric acid can be used) using a pH meter. Use an osmometer to check the osmolarity, which should be 290-300 mOsm. Afterward, pour the aCSF in a beaker and maintain in a water bath at 30 &#176;C.</li>
	</ol>
	</li>
</ol>
2. Brain dissection and slicing
NOTE: Since different brain structures may require cutting in different planes (coronal, sagittal, or horizontal slices), the exact approach for obtaining the slices depends on the brain region of interest. Typically, to study the Kiss1-expressing cells in the AVPV/PeN and ARH (here denominated as AVPV/PeNKisspeptin neurons and ARHkisspeptin neurons; Figure 2A,B), coronal brain slices (200-300 &#181;m) are usually made17,19,20,21,34. The AVPV/PeNKisspeptin neurons are located approximately 0.5 to -0.22 mm from the bregma, whereas ARHkisspeptin neurons are at -1.22 to -2.70 mm. Nuclei location can be determined by using a stereotaxic mouse brain atlas35 or the Allen Mouse Brain Reference Atlas (http://mouse.brain-map.org/). Adult Kiss1-Cre/GFP female (diestrus-stage) and male mice36 were used in this study.
<ol>
	<li>Brain removal
	<ol>
		<li>Prepare the dissection site and the tools needed to extract the brain: decapitation scissors, iris scissors, Castroviejo curved scissors, osteotome, tweezers, spatula, filter paper, Petri dish, razor blade, and cyanoacrylate glue.</li>
		<li>Before making the slices, prepare the bench on which the dissection will be performed, as all subsequent procedures must be performed quickly. Make sure to have access to a slicing device such as a vibratome.</li>
		<li>Prepare a recording chamber to maintain the brain slices before slicing the tissue. Acquire a recording chamber, bath dimensions of 24 mm x 15 mm x 2 mm (L x W x H), from a commercial brand (Table of Materials) or make one in-house. 
		NOTE: An in-house recovery chamber can be fabricated as follows: cut a 24-well plate so that nine wells are available. Glue a nylon screen to the base of the nine wells. With the remainder of the well plate, make a base so that the lower part of the nylon is free. This adapted base can be placed inside a 500 mL beaker containing the aCSF (Supplementary Figure 1).</li>
		<li>After preparing everything, anesthetize the animal with inhaled anesthetic using 4%-5% isoflurane. The anesthesia must be in accordance with a protocol approved by the ethics committee. Shortly after the animal is immobile, perform tail and paw pinch tests to ensure that the animal is deeply anesthetized.</li>
		<li>Quickly decapitate the mice while the heart is still active to augment cell viability. Harvest the brain quickly after decapitation.</li>
		<li>With surgical scissors, make an incision in the skin at the top of the animal&#39;s skull, from caudal to rostral, and remove the scalp from the animal&#39;s head. Next, cut the interparietal plate along the sagittal suture with the iris scissors and remove the occipital bone. Slide the osteotome under the parietal bone and gently pull it out until the brain is exposed.</li>
		<li>After exposing the brain, turn the head upside down, gently lower the brain to visualize the trigeminal nerve on each side, then cut the trigeminal nerve using Castroviejo curved scissors. After visualizing the hypothalamus, identify the optic nerve and cut it gently. 
		NOTE: Be careful when cutting the optic nerve, as pulling it will tear the adjacent hypothalamic area containing the AVPV/PeN nucleus.</li>
		<li>Cut the most anterior portion of the frontal lobe and remove the brain completely. Immediately immerse the brain in the slicing solution until acquiring the slices.</li>
	</ol>
	</li>
	<li>Slicing brain samples
	<ol>
		<li>Place the brain on filter paper (supported on a Petri dish) to dry the excess solution. Then, with a sharp cutting razor blade, perform a coronal cut separating the brainstem with the cerebellum from the rest of the tissue.</li>
		<li>Next, glue the caudal portion of the brain to the base of the vibratome and fill the chamber of the slicing device with the slicing/aCSF solution cooled to 0-2 &#176;C. During the procedure, pack dry ice around the vibratome chamber to keep the slicing solution cold.</li>
		<li>Insert the razor blade into the vibratome and set the device&#39;s appropriate cutting parameters: speed = 3, frequency = 9, and feed = 250 &#956;m. Use an acrylic transfer pipette (inverted Pasteur glass pipette attached to a silicone teat) to transfer the slices to the recovery chamber (described in step 2.1.3) during the tissue-slicing procedure. Wait 60 min for tissue recovery after slice acquisition.</li>
	</ol>
	</li>
</ol>
3. Cell sealing for recording
<ol>
	<li>Ensure that all the pieces of equipment (microscope, amplifier, digitizer, micromanipulator, and others) are turned on before starting the recording.</li>
	<li>Fill the recording chamber, from a commercial brand (Table of Materials), attached to the microscope with the aCSF solution for recordings. Use a perfusion pump to constantly perfuse the aCSF at a rate of 2 mL/min.</li>
	<li>Transfer a brain slice of interest (one at a time) to the recording chamber. Use an acrylic transfer pipette (inverted Pasteur glass pipette attached to a silicone teat) to transfer the hypothalamic slices to the chamber. Use a slice anchor (Table of Materials) to hold the slice so it does not move during the aCSF perfusion.</li>
	<li>Place a slice at the center of the recording chamber attached to the microscope. The slice position is critical to allow a good view of the desired region under the microscope and for a perfect reach of the recording micropipette.</li>
	<li>Use an immersion microscope&#39;s low-power objective lens (10x or 20x) to assist in positioning the slice and locating the region of interest.</li>
	<li>After locating the region of interest, switch the objective lens to the high-power lens (63x) and focus on the tissue level, observing the endogenous fluorescent protein and shapes of the cells in the target region to locate the kisspeptin cells on the surface of the brain slice20.</li>
	<li>When a possible target cell is located, mark it on the computer screen with the mouse cursor or by drawing a format, like a square, over the area of interest. The computer screen mark helps guide the recording micropipette&#39;s position to the cell.</li>
	<li>After determining the exact location of the target cell, lift the objective and introduce the recording micropipette filled with the internal solution. When placing the micropipette in the electrode holder, ensure that the internal solution is in contact with the silver electrode. 
	NOTE: For micropipette preparation, placement, and positioning on the electrode holder, please refer to33.</li>
	<li>Apply positive pressure before submerging the micropipette in the aCSF solution, to prevent debris from entering the micropipette, using a 1-3 mL air-filled syringe connected to the micropipette holder through a polyethylene tubing (&#8776;130 cm longer); apply nearly 100-200 &#956;L of air.</li>
	<li>Using the micromanipulator, guide the micropipette below the center of the objective. Move the buttons on the micromanipulator to guide the micropipette on the X-Y-Z axis toward the cell of interest.</li>
	<li>Adjust the focus to see the tip of the micropipette and bring the focus closer, but not too close, to the slice. Reduce the speed of the micromanipulator and slowly lower the micropipette to the plane of focus. Ensure that the micropipette tip does not abruptly penetrate the slice, but rather slowly descends until it touches the surface of the cell/target region.</li>
	<li>Apply light positive pressure (&#8776;100 &#956;L) with the 1-3 mL air-filled syringe attached to the micropipette holder to clear any debris from the approach path.</li>
	<li>Focus on the target cell and slowly move the micromanipulator on the X-Y-Z axis to bring the micropipette closer to the target cell. When touching the micropipette to the cell, a dimple caused by the pressure applied through the micropipette tip will be observed (Figure 2C).</li>
	<li>After forming the dimple, due to the micropipette&#39;s proximity to the cell, apply weak, brief suction by mouth (1-2 s) through the tube connected to the micropipette holder to generate the seal between the micropipette to the cell (gigaohm seal or gigaseal &#62;1 G&#8486;; Figure 2D). To form the seal, use the voltage-clamp mode on the software. For seal formation details, please refer to33.</li>
	<li>If the seal remains stable (the gigaohm seal should be mechanically stable and without noise interference, determined by observation for about 1 min), set the holding voltage at the closest physiological resting potential of the cell of interest. For kisspeptin hypothalamic neurons, -50 mV is recommended.</li>
	<li>Apply brief suction by mouth (negative pressure) with the micropipette sealed to the cell to break the plasma membrane (Figure 2E). Adequate whole-cell configuration is achieved when suction is performed with sufficient force so that the ruptured membrane does not clog the micropipette and does not attract a sizable portion of the membrane or even the cell.</li>
	<li>Check the system settings manual used. Use the software (see Table of Materials) to digitally check and calculate the series resistance (SR) and the whole-cell capacitance (wcc).</li>
	<li>On voltage-clamp mode, after breaking the cell membrane, enable the whole cell option, and click on the Auto command referring to the whole cell tab. The cell&#39;s SR and wcc will be automatically calculated and instantly displayed by the software. These parameters can also be checked by performing the membrane test with the amplifier mentioned in the Table of Materials33.</li>
	<li>Make sure to check cell viability parameters. For kisspeptin neurons, check that the electrophysiological measurements are: SR &#60; 25 m&#937;, input resistance &#62; 0.3 G&#937;, and holding current absolute value &#60; 30 pA (personal observations and reference21). The mean value of the wcc of AVPV/PeNKisspeptin or ARHkisspeptin neurons is &#8776; 10-12 pF in gonad-intact mice20.</li>
	<li>Monitor the SR and the cell steady-state capacitance during the experiments. Ensure the SR does not change more than 20% during a recording and that the membrane capacitance is stable.</li>
	<li>Check the software settings. Create specific protocols for the recordings according to the type of experiment. To record membrane potential in the current-clamp mode, with equipment mentioned in the Table of Materials, low-pass filter the electrophysiological signals at 2-4 kHz and analyze results offline in a software (see the Table of Materials for software information).</li>
	<li>Once the whole-cell configuration is properly achieved, measure synaptic currents in voltage-clamp mode (Figure 2G). Record changes in resting membrane potential (RMP) and induced RMP variations in the current-clamp mode (Figure 2H). Changes in RMP, such as depolarization of the cell membrane, can be induced by administering a known drug/neurotransmitter to the bath (described in step 3.2), as illustrated in Figure 1. 
	NOTE: In current-clamp mode, positive or negative current can be injected to hold the membrane voltage at a desired voltage. For kisspeptin neurons, we usually set zero current injection (I = 0) to record the spontaneous variation of the membrane potential.</li>
</ol>

No conflicts of interest to be declared.

The development of the whole-cell patch-clamp technique had a significant impact on the scientific community, being considered of paramount importance for developing scientific research and enabling several discoveries. Its impact on science was enough to culminate in the Nobel Prize in Medicine in 1991, as this discovery opened the door to a better understanding of how ion channels function under physiological and pathological conditions, as well as the identification of potential targets for therapeutic agents11,39,40,41. In the field of medicine, one of the outstanding findings made using this technique was that several substances used clinically interact directly with ion channels (e.g., local anesthetics, antiarrhythmics, antidiabetics, and muscle relaxants)42. Therefore, its applicability is evident in clinical institutes and basic research departments. This article describes the protocol for the basic preparation to perform whole-cell patch-clamp experiments on brain slices containing hypothalamic kisspeptin neurons. We outline the basic steps and highlight notable parameters that must be controlled to obtain tissue and prepare solutions for the patch-clamp technique. However, this article cannot fully describe the complexity of this technique and the mechanisms involved in each type of recording, especially the analysis. For further theoretical learning, some books and reviews on the patch-clamp technique are recommended10,43,44,45,46.
Each solution used in the patch-clamp method has a specific purpose; therefore, its specific compositions and criteria must be rigorously adopted during preparation. For example, the internal solution&#39;s composition should be determined according to the experiment&#39;s goal, since it varies depending on the type of current to be measured. The chloride-based solution mentioned here, in which Cl- (15 mM) mimics the physiological concentration of the cell cytoplasm47, is utilized to study active and passive neuronal properties or responses to synaptic input. It is important to emphasize that the chloride content in the internal solution keeps the chloride equilibrium potential at optimal levels for cell recording (in the mentioned solution ECL, it is about -59 mV). The intracellular chloride concentration can be estimated by evaluating the reversal potential for GABA-induced current (EGABA), assuming that all current through the GABAA receptor is carried by Cl-21,48. For the study of hypothalamic kisspeptin neurons, one must consider that the intracellular Cl- concentration for ARHkisspeptin is higher than for AVPV/PeNKisspeptin cells21. This characteristic must be considered when planning an experiment. The osmolarity of the internal solution is recommended to be at least 5% lower than that of aCSF for recordings to avoid loss of seal due to possible swelling and/or cell weakening33,47. If there is a need to add an intracellular compound that can be further used as a cell marker to the internal solution, such as biocytin or an intracellular dye (e.g., Alexa Fluor 594), K+ levels may be reduced so that osmolarity can be constantly maintained20,47,49,50.
Performing a rapid brain dissection and maintaining a low temperature (0-2 &#176;C) during slicing with an appropriate slicing solution is crucial. The slicing solutions may differ according to the type of cell and/or brain region being evaluated33,47. The aCSF solution used to obtain the brain slices (i.e., slicing solution) usually has a different composition from the aCSF for recordings (for comparison, see Table 2 and Table 3). The cation (Ca2+ and Mg2+) concentrations can be adjusted to modify the excitability of neurons, which can also affect the firing threshold and neurotransmitter release47. Low Ca2+&#160;and high Mg2+ media are widely utilized for minimizing possible excitotoxic processes (for more information, see51). In addition, low Ca2+ and high Mg2+ media can stimulate hypothalamic neuron activity52. Regarding the aCSF for recordings, some characteristics are similar. The buffer system is based on NaHCO3, high NaCl concentrations (generally &#62;100 mM) and low KCl concentrations (generally &#60;5 mM), relative concentrations of Ca2+ and Mg2+ (2:1 is often used) are usually around 2 mM, and glucose levels can range from 1 to 10 mM47. Besides variations of the solutions&#39; osmolarity, pH, or temperature changes (digitally controlled to be between 30-32 &#176;C), it is important to highlight that other issues may occur during the experimental protocol that substantially interfere with the experimentation. Electrophysiological measurements must be stable during the recordings, and any variations must have a critical reading. For example, SR changes account for cellular access in whole-cell mode and have considerable consequences on measured currents and potentials. Furthermore, it is important to emphasize that a relevant limitation related to the patch-clamp methodology that must be considered is mechanical overstimulation of the cell by excessive suction/pressure protocols that can induce morphological and functional changes53. This bias is often difficult to control in protocols where suction is performed by mouth rather than a device that can precisely control the suction intensity applied. Additionally, tissue-related issues, which culminate with a high percentage of cell mortality, may occur due to inadequate dissection, hypoxia, or the mouse&#39;s health condition that a researcher cannot identify by observation.
The main advantage of the whole-cell patch-clamp technique is the ability to record neurons in specific brain regions of interest precisely. This technique has tremendously benefited from the creation of genetically modified animals. Our group typically works with a mouse model that expresses the hrGFP under the Kiss1 gene promoter or another that expresses Cre-recombinase under the Kiss1 gene promoter and GFP under the Cre-conditional expression. However, there are many validated animal models nowadays23,26,36. In addition, the absence of the blood-brain barrier and the fact that the extracellular and intracellular environment can be easily controlled and manipulated represents advantages of this method; however, they do not necessarily represent a physiological condition. Among the limitations of this technique compared to in vivo preparations, or other recording types aiming to preserve the cytoplasmatic ionic concentration, such as on-cell or perforated-patch recordings, it is important to mention that the invasiveness of the whole-cell configuration causes dialysis of the cytoplasm content54. Dialysis may cause the interruption of molecular aspects necessary for some phenomena to develop or be expressed. By recording from slices, it needs to be remembered that most of the neurons&#39; projections are sectioned. Thus, it is out of the technique&#39;s scope to evaluate how much this disruption impacts the observed effects or a physiological condition. As mentioned, coronal brain slices of 200-300 &#956;m are usually performed to study the activity of hypothalamic kisspeptin neurons17,19,20,21,34. The limitation of using a thicker brain slice section to study kisspeptin cells and different slice angles maintaining specific AVPV/PeN or ARH connectivity55 needs further investigation. In addition, by testing the effect of a hormone/drug, synthetic or not, on the RMP of a neuron, several studies are based on the drug EC50 (if it is known) or on published data that demonstrate that a specific concentration is effective in activating firing rate or changing [Ca2+]i levels. However, one should be aware of the composition/specificity of the drug to be used in the experiments, as it is possible that purified synthetic drugs, compared to other similar drugs, may have antagonistic effects28. As demonstrated previously25, while purified pGH induces no effect on hypothalamic kisspeptin neuron activity, the hGH produced controversial data (see Figure 3). Similar results were demonstrated when insulin effects on the ARH were assessed28. Therefore, drug-specificity should be considered when planning an experiment and interpreting the obtained results.
The patch-clamp technique is an excellent tool for obtaining data about neuron electrical activity and has significantly contributed to the knowledge of several neuronal populations, such as the kisspeptin neurons. Most of the details provided here are generally used for recordings of hypothalamic neurons, as we have reported previously25,50,56,57,58,59,60. Importantly, for recording other neuronal populations besides kisspeptin neurons, one must know or determine the electrophysiological measurements that can help identify cell types, such as cell capacitance, SR, input resistance, cell firing pattern, and other parameters. These properties vary between different brain cells, brain nuclei, and physiological or induced conditions, such as circulating sex steroid levels16,19,20,21,61, which can substantially interfere with the critical analysis of the results. In addition, it is necessary to understand the possible variables involved in tissue preparation and their associated advantages and limitations to work with this technique. All the steps described here must be conducted judiciously, as any change in the variables involved in the protocol may drastically interfere with the results.

Hodgkin and Huxley made the first intracellular record of an action potential described in several scientific studies. This recording was performed on the squid axon, which has a large diameter (~500 &#181;m), allowing a microelectrode to be placed inside the axon. This work provided great possibilities for scientific research, later culminating in the creation of the voltage-clamp mode, which was used to study the ionic basis of action potential generation1,2,3,4,5,6,7,8. Over the years, the technique has been improved, and it has become widely applied in scientific research6,9. The invention of the patch-clamp technique, which took place in the late 1970s through studies initiated by Erwin Neher and Bert Sakmann, allowed researchers to record single ion channels and intracellular membrane potentials or currents in virtually every type of cell using only a single electrode9,10,11,12. Patch-clamp recordings can be made on a variety of tissue preparations, such as cultured cells or tissue slices, in either voltage-clamp mode (holding the cell membrane at a set voltage allowing the recording of, for example, voltage-dependent currents and synaptic currents) or current-clamp mode (allowing the recording of, for example, changes in resting membrane potential induced by ion currents, action potentials, and postsynaptic potential frequency).
The use of the patch-clamp technique made several notable discoveries possible. Indeed, the seminal findings on the electrophysiological properties of hypothalamic kisspeptin neurons located at the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeNKisspeptin), also known as the rostral periventricular area of the third ventricle (RP3V), and the arcuate nucleus of the hypothalamus (ARHkisspeptin)13,14,15 are of particular interest. In 2010, Ducret et al. performed the first recordings of AVPV/PeNKisspeptinneurons in mice using another electrophysiological tool, the loose-cell patch-clamp technique. These studies provided an electrical description of AVPV/PeNKisspeptin neurons and demonstrated that their firing patterns are estrous cycle-dependent16. In 2011, Qiu et al. used the whole cell patch-clamp technique to demonstrate that ARHkisspeptin neurons express endogenous pacemaker currents17. Subsequently, Gottsch et al. showed that kisspeptin neurons exhibit spontaneous activity and express both h-type (pacemaker) and T-type calcium currents, suggesting that ARHkisspeptin neurons share electrophysiological properties with other central nervous system pacemaker neurons18. Additionally, it has been demonstrated that ARHkisspeptin neurons exhibit sexually dimorphic firing rates and that AVPV/PeNKisspeptin neurons exhibit a bimodal resting membrane potential (RMP) influenced by ATP-sensitive potassium channels (KATP)19,20. Furthermore, it was established that gonadal steroids positively affect the spontaneous electrical activity of the kisspeptin neurons in mice19,20,21. The first works that study kisspeptin neurons&#39; electrophysiological properties are mentioned16,17,18,19,20. Since then, many studies have used the whole-cell patch-clamp technique to demonstrate which factors/neuromodulators are sufficient to modulate the electrical activity of kisspeptin neurons (Figure 1)17,21,22,23,24,25,26,27,28,29,30,31,32.
Given the importance of this technique for the study of neurons that are required for reproduction, among other cell types not covered here, this article describes the basic steps for the development of the whole-cell patch-clamp technique, such as preparing the solutions, dissecting and slicing the brain, and performing the seal of the cell membrane for recordings. Moreover, relevant issues about the technique are discussed, such as its advantages, technical limitations, and important variables that must be controlled for optimal experimental performance.

<table><tbody><tr><td>&lt;strong&gt;Compounds for aCSF, internal and slicing solutions&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>ATP</td><td>Sigma Aldrich/various</td><td>A9187</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma Aldrich/various</td><td>C7902</td><td></td></tr><tr><td>D-(+)-Glucose</td><td>Sigma Aldrich/various</td><td>G7021</td><td></td></tr><tr><td>EGTA</td><td>Sigma Aldrich/various</td><td>O3777</td><td></td></tr><tr><td>HEPES</td><td>Sigma Aldrich/various</td><td>H3375</td><td></td></tr><tr><td>KCL</td><td>Sigma Aldrich/various</td><td>P5405</td><td></td></tr><tr><td>K-gluconate</td><td>Sigma Aldrich/various</td><td>G4500</td><td></td></tr><tr><td>KOH</td><td>Sigma Aldrich/various</td><td>P5958</td><td></td></tr><tr><td>MgCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma Aldrich/various</td><td>M9272</td><td></td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma Aldrich/various</td><td>230391</td><td></td></tr><tr><td>NaCl</td><td>Sigma Aldrich/various</td><td>S5886</td><td></td></tr><tr><td>NaH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;&amp;nbsp;</td><td>Sigma Aldrich/various</td><td>S5011</td><td></td></tr><tr><td>NaHCO&lt;sub&gt;3&lt;/sub&gt;</td><td>Sigma Aldrich/various</td><td>S5761</td><td></td></tr><tr><td>nitric acid</td><td>Sigma Aldrich/various</td><td>225711</td><td>CAUTION</td></tr><tr><td>Sucrose</td><td>Sigma Aldrich/various</td><td>S1888</td><td></td></tr><tr><td>&lt;strong&gt;Equipments&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Air table</td><td>TMC</td><td>63-534</td><td></td></tr><tr><td>Amplifier</td><td>Molecular Devices</td><td>Multiclamp 700B</td><td></td></tr><tr><td>Computer</td><td>various</td><td>-</td><td></td></tr><tr><td>DIGIDATA 1440 LOW-NOISE DATA ACQUISITION SYSTEM</td><td>Molecular Devices</td><td>DD1440</td><td></td></tr><tr><td>Digital peristaltic pump</td><td>Ismatec</td><td>ISM833C&amp;nbsp;</td><td></td></tr><tr><td>Faraday cage</td><td>TMC</td><td>81-333-03</td><td></td></tr><tr><td>Imaging Camera</td><td>Leica</td><td>DFC 365 FX</td><td></td></tr><tr><td>Micromanipulator</td><td>Sutter Instruments</td><td>Roe-200</td><td></td></tr><tr><td>Micropipette Puller</td><td>Narishige</td><td>PC-10</td><td></td></tr><tr><td>Microscope</td><td>Leica</td><td>DM6000 FS</td><td></td></tr><tr><td>Osteotome</td><td>Bonther equipamentos &amp;amp; Tecnologia/various</td><td>128</td><td></td></tr><tr><td>Recovery chamber</td><td>Warner Instruments/Harvard apparatus</td><td>-</td><td>can be made in-house</td></tr><tr><td>Recording chamber</td><td>Warner Instruments</td><td>640277</td><td></td></tr><tr><td>Spatula</td><td>Fisher Scientific /various</td><td>FISH-14-375-10; FISH-21-401-20</td><td></td></tr><tr><td>Vibratome&amp;nbsp;</td><td>Leica</td><td>VT1000 S</td><td></td></tr><tr><td>Water Bath&amp;nbsp;</td><td>Fisher Scientific /various</td><td>Isotemp</td><td></td></tr><tr><td>&lt;strong&gt;Software and systems&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>AxoScope 10 software</td><td>Molecular Devices</td><td>-</td><td>Commander Software</td></tr><tr><td>LAS X wide field system</td><td>Leica</td><td>-</td><td>Image acquisition and analysis</td></tr><tr><td>MultiClamp 700B</td><td>Molecular Devices</td><td>MULTICLAMP 700B</td><td>Commander Software</td></tr><tr><td>PCLAMP 10 SOFTWARE FOR WINDOWS</td><td>Molecular Devices</td><td>Pclamp 10 Standard</td><td></td></tr><tr><td>&lt;strong&gt;Tools&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Ag/AgCl electrode, pellet, 1.0 mm</td><td>Warner Instruments</td><td>64-1309</td><td></td></tr><tr><td>Curved hemostatic forcep</td><td>various</td><td>-</td><td></td></tr><tr><td>cyanoacrylate glue</td><td>LOCTITE/various</td><td>-</td><td></td></tr><tr><td>Decapitation scissors</td><td>various</td><td>-</td><td></td></tr><tr><td>Filter paper</td><td>various</td><td>-</td><td></td></tr><tr><td>Glass capillaries (micropipette)</td><td>World Precision Instruments, Inc</td><td>TW150F-4</td><td></td></tr><tr><td>Iris scissors</td><td>Bonther equipamentos &amp;amp; Tecnologia/various</td><td>65-66</td><td></td></tr><tr><td>Pasteur glass pipette&amp;nbsp;</td><td>Sigma Aldrich/various</td><td>CLS7095B9-1000EA</td><td></td></tr><tr><td>Petri dish</td><td>various</td><td>-</td><td></td></tr><tr><td>Polyethylene tubing&amp;nbsp;</td><td>Warner Instruments</td><td>64-0756</td><td></td></tr><tr><td>Razor blade for brain dissection</td><td>TED PELLA</td><td>TEDP-121-1</td><td></td></tr><tr><td>Razor blade for the vibratome</td><td>TED PELLA</td><td>TEDP-121-9</td><td></td></tr><tr><td>Scissors</td><td>Bonther equipamentos &amp;amp; Tecnologia/various</td><td>71-72, 48,49;&amp;nbsp;</td><td></td></tr><tr><td>silicone teat</td><td>various</td><td>-</td><td></td></tr><tr><td>Slice Anchor&amp;nbsp;</td><td>Warner Instruments</td><td>64-0246</td><td></td></tr><tr><td>Syringe filters</td><td>Merck Millipore Ltda</td><td>SLGVR13SL</td><td>Millex-GV 0.22 &amp;mu;m</td></tr><tr><td>Tweezers</td><td>Bonther equipamentos &amp;amp; Tecnologia/various</td><td>131, 1518</td><td></td></tr></tbody></table>

hypothalamic kisspeptin neurons as a target for whole-cell patch-clamp recordings

Kisspeptins are essential for the maturation of the hypothalamic-pituitary-gonadal (HPG) axis and fertility. Hypothalamic kisspeptin neurons located in the anteroventral periventricular nucleus and rostral periventricular nucleus, as well as the arcuate nucleus of the hypothalamus, project to gonadotrophin-releasing hormone (GnRH) neurons, among other cells. Previous studies have demonstrated that kisspeptin signaling occurs through the Kiss1 receptor (Kiss1r), ultimately exciting GnRH neuron activity. In humans and experimental animal models, kisspeptins are sufficient for inducing GnRH secretion and, consequently, luteinizing hormone (LH) and follicle stimulant hormone (FSH) release. Since kisspeptins play an essential role in reproductive functions, researchers are working to assess how the intrinsic activity of hypothalamic kisspeptin neurons contributes to reproduction-related actions and identify the primary neurotransmitters/neuromodulators capable of changing these properties. The whole-cell patch-clamp technique has become a valuable tool for investigating kisspeptin neuron activity in rodent cells. This experimental technique allows researchers to record and measure spontaneous excitatory and inhibitory ionic currents, resting membrane potential, action potential firing, and other electrophysiological properties of cell membranes. In the present study, crucial aspects of the whole-cell patch-clamp technique, known as electrophysiological measurements that define hypothalamic kisspeptin neurons, and a discussion of relevant issues about the technique, are reviewed.

To study the possible effects of human recombinant growth hormone (hGH) on the activity of hypothalamic kisspeptin neurons, we performed whole-cell patch-clamp recordings in brain slices and assessed whether this hormone causes acute changes in the activity of AVPV/PeNKisspeptin and ARHkisspeptin neurons. Adult Kiss1-Cre/GFP female (diestrus-stage) and male mice36 were used in this study.&#160;Gonad-intact animals were selected for the experiments, since the properties of their hypothalamic kisspeptin neurons may vary depending on sex steroid levels19,20. While it was beyond the scope of the present study to evaluate differences between sexes, we refer the reader to Croft et al. and Fraz&#227;o et al.19,20&#160;for more information. Genetically modified animals, such as mice and rats, represent exciting tools for this type of experiment, since cells expressing a specific gene or a selective-induced ablation can be identified by a fluorescent protein such as GFP, among others23,26,36. The use of genetically modified mice represents a breakthrough in understanding kisspeptin neuron activity.&#160;
Recorded neurons (26 cells out of 12 animals) were determined according to neuroanatomical features35 and the expression of the endogenous GFP20. In current-clamp mode, neurons were recorded under I = 0 in whole-cell patch-clamp configuration. The AVPV/PeNKisspeptin neurons (12 cells from nine animals) exhibited an average RMP of -59.0 mV &#177; 3.0 mV (range: -75 mV to -46 mV), input resistance of 0.9 &#177; 0.1 G&#937;, wcc of 12.3 pF &#177; 1.6 pF, and SR of 19.4 &#177; 1.9 m&#937;. Among the recorded neurons, three out of 12 AVPV/PeNKisspeptin cells showed spontaneous discharges of action potentials (APs) at rest (0.1 Hz &#177; 0.06 Hz; average RMP of the spontaneously active cells was -50.7 mV &#177; 2.7 mV). The average RMP of ARHkisspeptin neurons (14 cells from 12 animals) was -50.0 mV &#177; 1.5 mV (range: -62 mV to -39 mV), the average input resistance was 1.7 &#177; 0.1 G&#937;, wcc was 9.2 pF &#177; 0.7 pF, and SR of 16.9 &#177; 1.7 m&#937;. Most ARHkisspeptin neurons were quiescent, whereas four out of 14 cells showed spontaneous APs at rest (0.9 Hz &#177; 0.5 Hz; average RMP of the spontaneously active cells was -52.7 mV &#177; 1.4 mV).
The administration of hGH (20 &#181;g/g) to the bath induced a significant hyperpolarization of the RMP of many of the recorded neurons, five out of 12 AVPV/PeNKisspeptin neurons (&#8776;55% of cells from 9 mice), and nine out of 14 recorded ARHkisspeptin neurons (&#8776;65% of cells from 12 mice, p = 0.0006, Fisher&#39;s exact test; Figure 3). The AVPV/PeNKisspeptin and ARHkisspeptin hyperpolarized neurons significantly changed the RMP compared to the unresponsive cells (Figure 3B,E; Mann-Whitney test). The effects on RMP (Figure 3C,F; repeated measures ANOVA and Tukey&#39;s post-test) were followed by a significant reduction of the whole-cell input resistance (IR) on AVPV/PeNKisspeptin (0.9 &#177; 0.1 G&#937; to 0.7 &#177; 0.1 G&#937; during hGH application, p = 0.02; Figure 3D), and on ARHkisspeptin (1.7 &#177; 0.1 G&#937; to 1.0 &#177; 0.1 G&#937; during hGH application, p &#60; 0.0001; repeated measures ANOVA and Tukey&#39;s post-test; Figure 3G) neurons. Additionally, the frequency of spontaneous APs (fAPs) of hGH-hyperpolarized neurons decreased in both populations of cells (0.1 Hz &#177; 0.06 Hz to 0.0 Hz &#177; 0.0 Hz in AVPV/PeNKisspeptin and 1.0 Hz &#177; 0.5 Hz to 0.2 Hz &#177; 0.1 Hz in ARHkisspeptin neurons). However, the extent of this decrease failed to reach a level of statistical significance (p &#62; 0.05, Mann-Whitney test). After the hGH washout, the RMP and IR were restored to baseline (Figure 3A,C,D,F,G). The remaining kisspeptin neurons were unresponsive to hGH administration.
We have previously demonstrated that pGH induces no effects on hypothalamic kisspeptin neuron activity (please refer to Silveira et al.25; Figure 3H). Of note, it is known that hGH can activate prolactin (PRL) receptors in addition to GH receptors37,38. Besides, PRL indirectly depolarizes only &#8776;20% of AVPV/PeNKisspeptin neurons in mice24. In contrast, PRL does not modulate the fast synaptic transmission of the ARHkisspeptin cells24. Therefore, the hGH-induced hyperpolarization effect reported here seems to be nonspecific. The observed differences may depend on variables such as drug concentration, species difference (human vs. mouse), or even the presence of salts in the composition of the used drugs, as previously reported28.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64989/64989fig01.jpg" /> 
Figure 1: Schematic diagram summarizing the whole-cell patch-clamp technique&#39;s contribution to the knowledge of the kisspeptin neurons&#39; activity. Kisspeptin neurons (shown in green) are located in the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN) and arcuate nucleus of the hypothalamus (ARH). The AVPV/PeNKisspeptin and ARHkisspeptin cells send direct connections to gonadotrophin-releasing hormone (GnRH) neurons&#39;&#160;soma located in the preoptic area (POA) and their terminals at the median eminence (ME), culminating in the modulation of the hypothalamus-pituitary-axis (HPG). Different neuromodulators, such as hormones, have been shown to differentially modulate the activity of the AVPV/PeNKisspeptin and ARHkisspeptin neurons. Possible effects on the resting membrane potential are schematically demonstrated by representative tracings obtained using the whole-cell path-clamp technique and current-clamp recordings. The red color indicates that a specific neurotransmitter induces the depolarization of the resting membrane potential (RMP)17,22,24,26,28,29,30,31,32; the blue color indicates no effect on RMP24,25,26,27,30. The dashed line indicates the RMP. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64989/64989fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/64989/64989fig02.jpg" /> 
Figure 2: Basic steps to obtain the sealing of the cell of interest by the whole-cell patch-clamp technique. (A,B) Representative photomicrographs of brain slices (250 &#181;m) containing kisspeptin cells at the anteroventral periventricular nucleus (AVPV) and arcuate nucleus of the hypothalamus (ARH). Kisspeptin neurons were identified by green fluorescent protein (GFP) expression. (C) Photomicrograph demonstrating a micropipette (containing electrolyte solution [internal solution]) close enough to the cell to create a dimple in the plasma membrane to perform the seal. (D,E) Mild negative pressure (mouth suction performed on a tube attached to the headstage and micropipette) is required to seal the cell membrane to the micropipette (D). A second application of negative pressure (mild and brief) is necessary to induce the plasma membrane rupture (E). (F) The registration of the cell activity is performed by a mechanical setup used for patch-clamp experiments. After breaking the plasma membrane, currents flowing through the ionic channels in the patched cell can be recorded by an electrode connected to a highly sensitive amplifier. A feedback resistor generates the current needed for voltage-clamp (G) or current-clamp (H) recordings. Abbreviations: 3V = third ventricle; ME = median eminence. Scale bars: A = 130 &#181;m, B = 145 &#181;m, C = 20 &#181;m, D = 15 &#181;m. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64989/64989fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/64989/64989fig03.jpg" /> 
Figure 3: Testing drug specificity. (A) Representative current-clamp recording demonstrating that human recombinant growth hormone (hGH) induced a hyperpolarization of the resting membrane potential (RMP) of the kisspeptin neurons located at the arcuate nucleus of the hypothalamus (ARHkisspeptin). (B-G) Bar graphs demonstrating the average change in the resting membrane potential (RMP) (B,C,E,F) and average input resistance (IR) (D,G) of hGH-responsive kisspeptin neurons located at the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeNKisspeptin) (B-D) or ARH (E-G). Representative current-clamp recording demonstrating that porcine growth hormone (pGH) induced no effect on the RMP of ARHkisspeptin neurons, as previously reported25&#160;(H).&#160;The significance tests used are the Mann-Whitney test for (B) and (E), and repeated measures ANOVA and Tukey&#39;s post-test for (C,D,F,G). The dashed line indicates the RMP. *p = 0.02; **p = 0.004,***p = 0.0003; ****p &#60; 0.0001. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64989/64989fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="4">Internal Solution (100 mL)</td>
		</tr>
		<tr>
			<td>Salt</td>
			<td>FW (g/mol)</td>
			<td>Concentration</td>
			<td>Weight (g)</td>
		</tr>
		<tr>
			<td>K-gluconate</td>
			<td>234.2</td>
			<td>120 mM</td>
			<td>2.81</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>58.4</td>
			<td>1.0 mM</td>
			<td>0.006</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>74.5</td>
			<td>10 mM</td>
			<td>0.074</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>238.3</td>
			<td>10 mM</td>
			<td>0.24</td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>380.3</td>
			<td>5.0 mM</td>
			<td>0.19</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>147.0</td>
			<td>1.0 mM</td>
			<td>0.015</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>203.0</td>
			<td>1.0 mM</td>
			<td>0.02</td>
		</tr>
		<tr>
			<td>KOH</td>
			<td>56.11</td>
			<td>3.0 mM</td>
			<td>0.017</td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>507.18</td>
			<td>4.0 mM</td>
			<td>0.20</td>
		</tr>
		<tr>
			<td colspan="4">pH =7.3 / osmolarity = 275 - 280 mOsm</td>
		</tr>
	</tbody>
</table>
Table 1: Reagents for the preparation of the internal solution. The table contains the molecular weight (FW), desired concentrations, and the calculated weight of the salts for the preparation of 100 mL of solution.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="4">aCSF/Slicing Solution (250 mL)</td>
		</tr>
		<tr>
			<td>Salt</td>
			<td>FW</td>
			<td>Concentration</td>
			<td>Weight (g)</td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>342.3</td>
			<td>238 mM</td>
			<td>18.5</td>
		</tr>
		<tr>
			<td>KCL</td>
			<td>74.5</td>
			<td>2.5 mM</td>
			<td>0.046</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>84.0</td>
			<td>26 mM</td>
			<td>0.546</td>
		</tr>
		<tr>
			<td>NaH2PO4</td>
			<td>120.0</td>
			<td>1.0 mM</td>
			<td>0.03</td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>203.0</td>
			<td>5 mM</td>
			<td>0.254</td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>180.2</td>
			<td>10 mM</td>
			<td>0.450</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>147.0</td>
			<td>1.0 mM</td>
			<td>0.037</td>
		</tr>
		<tr>
			<td colspan="4">pH = 7.3 / osmolarity = 290 - 295 mOsm</td>
		</tr>
	</tbody>
</table>
Table 2: Reagents to prepare the slicing solution. The table contains the molecular weight (FW), desired concentrations, and calculated weight of the salts for the preparation of 250 mL of solution. The brain is submerged in this solution to be sliced.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="4">aCSF for recording (1 L)</td>
		</tr>
		<tr>
			<td>Salt</td>
			<td>FW</td>
			<td>Concentration</td>
			<td>Weight (g)</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>58.4</td>
			<td>135 mM</td>
			<td>7.88</td>
		</tr>
		<tr>
			<td>KCL</td>
			<td>74.5</td>
			<td>3.5 mM</td>
			<td>0.261</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>84.0</td>
			<td>26 mM</td>
			<td>2,184</td>
		</tr>
		<tr>
			<td>NaH2PO4</td>
			<td>120.0</td>
			<td>1.25 mM</td>
			<td>0.150</td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>246.5</td>
			<td>1.2 mM</td>
			<td>0.296</td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>180.2</td>
			<td>10 mM</td>
			<td>1,802</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>147.0</td>
			<td>1.0 mM</td>
			<td>0.148</td>
		</tr>
		<tr>
			<td colspan="4">pH = 7.3 / osmolarity = 290-300 mOsm</td>
		</tr>
	</tbody>
</table>
Table 3: Reagents to prepare aCSF for recordings. The table contains the molecular weight (FW), desired concentrations, and calculated weight of the salts for the preparation of 1 L of solution.
Supplementary Figure 1: Example of an in-house made recovery chamber. (A,B) An in-house recovery chamber can be fabricated as follows: cut a 24-well plate so that nine wells are available. Glue a nylon screen to the base of the nine wells. With the remainder of the well plate, make a base so that the lower part of the nylon is free. (C) This adapted base can be placed inside a 500 mL beaker containing artificial cerebrospinal spinal fluid (aCSF) constantly saturated with carbogen (95% O2 and 5% CO2). (D) The beaker holding the recovery chamber is kept in the water bath during experimentation. (E,F) An acrylic transfer pipette is used to transfer the brain slices to the recovery chamber. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64989/Suplementtary figure 1.tif" target="_blank">Please click here to download this File.</a>

Watch this Scientific Journal Video about Hypothalamic Kisspeptin Neurons as a Target for Whole-Cell Patch-Clamp Recordings at JoVE.com

Hypothalamic Kisspeptin Neurons as a Target for Whole-Cell Patch-Clamp Recordings

Here, we present a protocol to perform a whole-cell patch-clamp on brain slices containing kisspeptin neurons, the primary modulator of gonadotrophin-releasing hormone (GnRH) cells. By adding knowledge about kisspeptin neuron activity, this electrophysiological tool has served as the basis for significant advancements in the neuroendocrinology field over the last 20 years.

Kisspeptins are essential for the maturation of the hypothalamic-pituitary-gonadal (HPG) axis and fertility. Hypothalamic kisspeptin neurons located in ...

hypothalamic-kisspeptin-neurons-as-target-for-whole-cell-patch-clamp

Nanyang Technological University

Research

JoVE Journal

Neuroscience

1.9K Views.  Universidade de Sao Paulo. Here, we present a protocol to perform a whole-cell patch-clamp on brain slices containing kisspeptin neurons, the primary modulator of gonadotrophin-releasing hormone (GnRH) cells. By adding knowledge about kisspeptin neuron activity, this electrophysiological tool has served as the basis for significant advancements in the neuroendocrinology field over the last 20 years.

Video: Hypothalamic Kisspeptin Neurons as a Target for Whole-Cell Patch-Clamp Recordings

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological measurement of single or multiple ion channels in cells. This technique can be applied to ion channels in both their native environment and expressed in heterologous cells, such as oocytes harvested from the African clawed frog, Xenopus laevis. Here, we describe the well-established technique of patch clamp recording from Xenopus oocytes. This technique is used to measure the properties of expressed ion channels either in populations (macropatch) or individually (single-channel recording). We focus on techniques to maximize the quality of oocyte preparation and seal generation. With all factors optimized, this technique gives a probability of successful seal generation over 90 percent. The process may be optimized differently by every researcher based on the factors he or she finds most important, and we present the approach that have lead to the greatest success in our hands.

This is intended as an introduction to patch clamp recording from Xenopus laevis oocytes. It covers vitelline membrane removal, formation of a gigaohm seal (gigaseal), and the optional conversion of the patch to the outside-out topology.

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological ...

Biology

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 ...

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 ...

Subcellular Patch-clamp Recordings from the Somatodendritic Domain of Nigral Dopamine Neurons

Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding these fundamental functions will shed light on the information transfer in these neurons. Dendritic patch-clamp recordings provide the possibility to directly examine the electrical properties of dendrites and underlying voltage-gated ion channels. However, these fine structures are not easily accessible to patch pipettes because of their small diameter. This report describes a step-by-step procedure to collect stable and reliable recordings from the dendrites of dopaminergic neurons in acute slices. Electrophysiological measurements are combined with post hoc recovery of cell morphology. Successful experiments rely on improved preparation of slices, solutions and pipettes, adequate adjustment of the optics and stability of the pipette in contact with the recorded structure. Standard principles of somatic patch-clamp recording are applied to dendrites but with a gentler approach of the pipette. These versatile techniques can be implemented to address various questions concerning the excitable properties of dendrites.

Subcellular patch-clamp recordings offer the possibility to investigate the functional properties of dendrites. However these fine structures are not easily accessible due to their small diameter. The protocol described here aims to facilitate the collection of stable and reliable recordings from the dendrites of dopamine neurons in slices in vitro.

Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding ...

Evaluation of Synaptic Multiplicity Using Whole-cell Patch-clamp Electrophysiology

In the central nervous system, a pair of neurons often form&#160;multiple synaptic contacts and/or functional neurotransmitter release sites (synaptic multiplicity). Synaptic multiplicity is plastic and changes throughout development and in different physiological conditions, being an important determinant for the efficacy of synaptic transmission. Here, we outline experiments for estimating the degree of multiplicity of synapses terminating onto a given postsynaptic neuron using whole-cell patch clamp electrophysiology in acute brain slices. Specifically, voltage-clamp recording is used to compare the difference between the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs). The theory behind this method is that afferent inputs that exhibit multiplicity will show large, action potential-dependent sEPSCs due to the synchronous release that occurs at each synaptic contact. In contrast, action potential-independent release (which is asynchronous) will generate smaller amplitude mEPSCs. This article outlines a set of experiments and analyses to characterize the existence of synaptic multiplicity and discusses the requirements and limitations of the technique. This technique can be applied to investigate how different behavioral, pharmacological or environmental interventions in vivo affect the organization of synaptic contacts in different brain areas.

Here, we present a protocol for evaluating the functional synaptic multiplicity using whole-cell patch clamp electrophysiology in acute brain slices.

In the central nervous system, a pair of neurons often form&#160;multiple synaptic contacts and/or functional neurotransmitter release sites (synaptic ...

Patch Clamp Electrophysiology

Neuron cell membranes are populated with ion channels that control the movement of charge into and out of the cell, thereby regulating neuron firing. One extremely useful technique for investigating the biophysical properties of these channels is called patch clamp recording. In this method, neuroscientists place a polished glass micropipette against a cell and apply suction to form a high resistance seal. This process isolates a small &#8220;patch&#8221; of membrane that contains one or more ion channels. Using an electrode within the micropipette, researchers can &#8220;clamp&#8221; or control the electrical properties of the membrane, which is important for analysis of channel activity. The electrode also allows for changes in the voltage across the membrane, or the flow of ions through the membrane, to be recorded. This video begins with an overview of the principles behind patch clamp electrophysiology, an introduction to the necessary equipment, and descriptions of the various patch configurations, including whole cell, cell-attached, perforated, inside-out, and outside-out patches. Next, the key steps of a typical whole-cell patch clamp experiment are outlined, in which a current-voltage (IV) curve is generated. Finally, applications of patch clamp recording are provided to demonstrate how the biophysical properties of ion channels, cell excitability, and neuroactive compounds are evaluated in neurophysiology labs today.

Patch Clamp Electrophysiology: Principle &amp; Applications

Neuron cell membranes are populated with ion channels that control the movement of charge into and out of the cell, thereby regulating neuron firing. One ...

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Advanced Biology

Whole-Cell Patch Clamp Electrophysiology: A Method to Study Electrical Properties of Neurons

Source: Roy, B., et al. <a href="https://www-jove-com.remotexs.ntu.edu.sg/v/50551/" target="_blank">Patch Clamp Recordings from Embryonic Zebrafish Mauthner Cells</a>. J. Vis. Exp. (2013).
This protocol describes a technique called whole-cell patch clamp electrophysiology, which is a method to study electrical properties of Mauthner neurons and other reticulospinal cells in zebrafish embryos.

Elektrofizjologia klamer krosowych całych komórek: metoda badania właściwości elektrycznych neuronów

Source: Roy, B., et al. Patch Clamp Recordings from Embryonic Zebrafish Mauthner Cells. J. Vis. Exp. (2013).
This protocol describes a technique called ...

JoVE Encyclopedia of Experiments

Danio rerio (zebrafish)

Embryo

Determining a Test Growth Hormone Effect on Kisspeptin Neurons using a Whole-Cell Patch Clamp

Source: Silva, J. d. N., et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/64989">Hypothalamic Kisspeptin Neurons as a Target for Whole-Cell Patch-Clamp Recordings.</a> J. Vis. Exp. (2023)
This video demonstrates the use of the whole-cell patch-clamp technique to measure responses in kisspeptin neurons from transfected mouse hypothalamic slices. The process involves achieving whole-cell configuration and recording membrane potential changes induced by the test hormone using current-clamp mode.

Określanie testowego wpływu hormonu wzrostu na neurony kisspeptyny za pomocą zacisku łatkowego dla całych komórek

All procedures involving animal samples have been reviewed and approved by the appropriate animal ethical review committee.
1. Cell sealing for recording

...

Neurophysiology

Stimulation and Modulation Techniques

Studying the Excitability of Fluorescent Neurons using a Whole-Cell Patch Clamp

Source: Briz, C. G., et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/55139">In Utero Electroporation Approaches to Study the Excitability of Neuronal Subpopulations and Single-cell Connectivity.</a> J. Vis. Exp. (2017)
The video demonstrates a method to study the excitability of neuronal cells expressing fluorescent protein using a whole-cell patch current clamp. In the current-clamp mode, action potentials indicative of neuronal excitability are generated.

Badanie pobudliwości neuronów fluorescencyjnych za pomocą klamry krosowej dla całych komórek

All procedures involving animal samples have been reviewed and approved by the appropriate animal ethical review committee.
1. Electrophysiology
NOTE: The ...

Electrophysiology Techniques

Photostimulation and Whole-Cell Patch Clamp Recordings of Neurons in Mouse Hippocampal Slices

Source: Richevaux, L., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/59534">In Vivo Intracerebral Stereotaxic Injections for Optogenetic Stimulation of Long-Range Inputs in Mouse Brain Slices.</a> J. Vis. Exp. (2019)
The video demonstrates a protocol to study synaptic interactions and neuronal responses in a transfected mouse hippocampal brain slice. It involves illuminating long-range sensory neurons to trigger action potentials and recording the resulting excitatory post-synaptic potentials in the recorded neuron using the whole-cell patch-clamp technique.

All procedures involving animal samples have been reviewed and approved by the appropriate animal ethical review committee.
1. Solutions for acute slice ...