Name: isolating and culturing vestibular and spiral ganglion somata from neonatal rodents for patch-clamp recordings
Uploaded: 2023-04-21T12:40:00
Description: Watch this Scientific Journal Video about Isolating and Culturing Vestibular and Spiral Ganglion Somata from Neonatal Rodents for Patch-Clamp Recordings at JoVE.com

We acknowledge Drs. Jing Bing Xue and Ruth Anne Eatock for their early contributions to these methods. This work was supported by NIH NIDCD R03 DC012652 and NIH NIDCD DC012653S, and R01 DC0155512 to RK and T32 DC009975 to DB, NN, and KR.

All animal use described here has been approved by the Institutional Animal Care and Use Committee at the University of Southern California. Animals in this protocol are P3- to P25-aged Long Evans rats of both sexes obtained from Charles River Laboratories, but these methods can be applied to other rodent strains. A laboratory coat and gloves must be worn during all procedures, as well as splash-protective goggles when making solutions.
1. Preparations
<p class="jove_content...

<ol>
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The methods presented here are specific to recordings from isolated neurons; previous studies have focused on recordings from axon terminals in a semi-intact preparation. When compared to existing terminal recording techniques, isolated recordings offer superior space-clamp and iso-potential behavior. In addition, this protocol provides access to a broader sample of neurons, since only calyx-bearing subpopulations are accessible in semi-intact recordings of the vestibular epithelia. Finally, isolated recordings allow for...

The bipolar neurons of the vestibulocochlear nerve connect the sensory hair cells of the inner ear to the brainstem. They are principal carriers of information about sound and head movements; damage to these important cells leads to deafness and balance disorders. The vestibular and auditory portions of the nerve are each comprised of distinct cell types that are&#160;morphologically and functionally diverse1,2. In the vestibular system, two afferent subpopulations fire spontaneously at intervals that are either regular or irregular2. Afferent spike timing is thought to reflect an underlying diversity in ion channel composition3,4. In the auditory system, there are two main subpopulations of spiral ganglion neurons (SGNs); whereas Type I SGNs contact individual inner hair cells5, Type II SGNs contact multiple outer hair cells5. In vitro recordings from semi-intact and organotypic cultures suggest differences in the membrane properties of Type I and Type II SGNs6,7.
Many ion channels and neurotransmitter receptors found at the terminals of these neurons are also found in their cell bodies. As such, cultures of the isolated vestibular and the spiral ganglion somata can be studied in vitro to understand how ion channels and neurotransmitter receptors contribute to the response of these neurons. The compact morphology of the isolated cell bodies allows for high-quality electrical recordings, suitable for detailed characterization of voltage-gated ion channels and neurotransmitter receptors. Easy access to a representative variety of neuron subtypes allows for high-throughput analysis of cell diversity.
This article presents a method for isolating and culturing dissociated ganglion cell bodies from the superior portion of the vestibular ganglion in rats at postnatal day (P)9 to P20. Suggestions are also provided for extending these methods to the spiral ganglion, in addition to the steps required for successfully extracting, dissociating, and plating the ganglion cells. These methods are an evolution of those devised in publications from various laboratories8,9,10. Also included in this paper is guidance for selecting healthy cells for patch-clamp recordings.
Finally, the protocol outlines the procedure for patch-clamp recording using the perforated-patch configuration11. Though the perforated-patch configuration is more time-consuming and more technically challenging than the more common ruptured-patch configuration, it is better for maintaining the cytoplasmic milieu that allows for long and stable recording sessions. The benefits of this recording configuration are illustrated here through the improved stability of hyperpolarization-activated cationic currents in perforated-patch relative to ruptured-patch recordings.
This protocol is organized into five sections. Sections 1-3 describe solutions and tools that can be prepared and stored ahead of time. Section 4 describes the steps for dissecting and plating the vestibular and SGNs. Section 5 describes the steps for recording from the neurons after a period in culture. In our hands, section 4 and section 5 are performed over a period of 2 consecutive days.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Amphotericin</td>
			<td>Sigma-Aldrich</td>
			<td>A4888-100MG</td>
			<td>For perforated patch recordings.</td>
		</tr>
		<tr>
			<td>ATP di-sodium</td>
			<td>Sigma-Aldrich</td>
			<td>A7699</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>B27 Supplement (50x), serum free</td>
			<td>Thermo Fisher Scientific</td>
			<td>17504044</td>
			<td>additive to culture medium, for SGN</td>
		</tr>
		<tr>
			<td>Beakers (1000, 100, 10) milliliter</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>bench-top centrifuge</td>
			<td>USA Scientific</td>
			<td>2641-0016</td>
			<td></td>
		</tr>
		<tr>
			<td>Bunsen burner</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>J.T. Baker</td>
			<td>1311-01</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>Collagenase</td>
			<td>Sigma-Aldrich</td>
			<td>C5318</td>
			<td>one out of three enzyme to digest tissue</td>
		</tr>
		<tr>
			<td>Coverglass, rectangular, #1 thickness, 22x40&#160;</td>
			<td>Warner Instruments</td>
			<td>64-0707</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Biotium</td>
			<td>90082</td>
			<td></td>
		</tr>
		<tr>
			<td>Dnase I,from bovine pancreas</td>
			<td>Sigma-Aldrich</td>
			<td>11284932001</td>
			<td>one out of three enzyme to digest tissue</td>
		</tr>
		<tr>
			<td>Dumont #3 Forceps (Blunt)</td>
			<td>Fine Science Tools</td>
			<td>11231-30</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 Forceps (Fine)</td>
			<td>Fine Science Tools</td>
			<td>11251-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #55 Forceps (Fine)</td>
			<td>Fine Science Tools</td>
			<td>11255-20</td>
			<td></td>
		</tr>
		<tr>
			<td>EGTA</td>
			<td>Sigma-Aldrich</td>
			<td>E0396</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>Electrode Puller</td>
			<td>Narashige</td>
			<td>PC-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Epi-illumination light source&#160;</td>
			<td>Zeiss&#160;</td>
			<td>CL 1500 ECO</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Decon Labs</td>
			<td>2716</td>
			<td>for cleaning head and around dissection bench</td>
		</tr>
		<tr>
			<td>Filamented Borosilicate Capillaries for electrodes</td>
			<td>Sutter Instruments</td>
			<td>BF140-117-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine-edged dissection blade</td>
			<td>Fine Science Tools</td>
			<td>10010-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Pasteur Pipettes</td>
			<td>VWR</td>
			<td>14673-010</td>
			<td>to pull trituration pipettes</td>
		</tr>
		<tr>
			<td>Heat-inactivated Fetal Bovine Serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>16140063</td>
			<td>additive to culture medium</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H3375-100G</td>
			<td>for pH buffering all solutions in protocol</td>
		</tr>
		<tr>
			<td>Hot plate / magnetic stirrers&#160;</td>
			<td>VWR</td>
			<td>76549-914</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulated bucket filled with ice</td>
			<td></td>
			<td></td>
			<td>to keep all samples and solutions cool</td>
		</tr>
		<tr>
			<td>K2SO4, Potassium Sulfate</td>
			<td>Sigma Aldrich</td>
			<td>P9458-250G</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma-Aldrich</td>
			<td>P93333</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>KOH (1 M)</td>
			<td>Honeywell</td>
			<td>319376-500ML</td>
			<td>To bring internal solution to desired pH.</td>
		</tr>
		<tr>
			<td>Large Spring Scissors</td>
			<td>Fine Science Tools</td>
			<td>14133-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Leibovitz medium&#160;</td>
			<td>Sigma Aldrich</td>
			<td>L4386</td>
			<td>dissection and bath solutions&#160;</td>
		</tr>
		<tr>
			<td>Low-profile-bath recording chamber for culture dishes</td>
			<td>Warner Instruments</td>
			<td>64-0236</td>
			<td></td>
		</tr>
		<tr>
			<td>luer-lok syringes, 30 ml</td>
			<td>BD</td>
			<td>302832</td>
			<td>for drawing L-15/HEPES/HEPES solution.</td>
		</tr>
		<tr>
			<td>MEM + Glutamax Supplement</td>
			<td>Fisher Scientific</td>
			<td>41-090-101</td>
			<td>base of the culture medium</td>
		</tr>
		<tr>
			<td>MgCl2-Hexahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>M1028</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>microFil needle for filling micropipettes - 34 gauge&#160;</td>
			<td>World Precision Instruments</td>
			<td>MF34G</td>
			<td></td>
		</tr>
		<tr>
			<td>Microforge</td>
			<td>Narashige</td>
			<td>MF-90</td>
			<td>For electrode polishing.</td>
		</tr>
		<tr>
			<td>N2 Supplement (100x)</td>
			<td>Thermo Fisher Scientific</td>
			<td>17502-048</td>
			<td>additiive to culture medium, for SGN</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S7653</td>
			<td>Additive to internal solution</td>
		</tr>
		<tr>
			<td>NaOH (1 M)</td>
			<td>Thomas Scientific</td>
			<td>319511-500ML</td>
			<td>for titration pH</td>
		</tr>
		<tr>
			<td>Osmometer</td>
			<td>Advanced Instruments Inc.</td>
			<td>3320</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen, Medical grade, with adequate regulator and tubing</td>
			<td>USC Material Management</td>
			<td>MEDOX200 (Identifier: 00015)</td>
			<td>for dissolving into dissection and bath solutions</td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Bemis</td>
			<td>PM992</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette bulb (3 ml)</td>
			<td>Fisher Scientific</td>
			<td>03-448-25</td>
			<td>bulb for trituration pipettes</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Thermo Fisher Scientific</td>
			<td>15140122</td>
			<td>additive to prevent contamination of culture medium</td>
		</tr>
		<tr>
			<td>Pentobarbital based euthanasia solution (e.g., Fatal Plus. 50 &#8211; 60 mg/kg dosing)&#160;</td>
			<td>MWI Animal Health</td>
			<td>15199</td>
			<td>for euthanasia</td>
		</tr>
		<tr>
			<td>PES membrane filters ,&#160; 0.2 micrometer&#160;</td>
			<td>Nalgene</td>
			<td>566-0020</td>
			<td>for filtering solutions</td>
		</tr>
		<tr>
			<td>PES membrane sterile syringe filters, 0.22 um, 30 mm&#160;</td>
			<td>CELLTREAT</td>
			<td>229747</td>
			<td>for filtering solutions drawn into syringes</td>
		</tr>
		<tr>
			<td>Petri dishes, 35 x 10 mm</td>
			<td>Genessee Scientific</td>
			<td>32-103</td>
			<td>for micro dissection and to hold Tip dip solution in perforated-patch configuration</td>
		</tr>
		<tr>
			<td>Petri Dishes, 60 x 15 mm</td>
			<td>Midland Scientific</td>
			<td>P7455</td>
			<td>for gross dissection</td>
		</tr>
		<tr>
			<td>pH Meter</td>
			<td>Mettler Toledo</td>
			<td>Model S20</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipettors (1000, 200, 10) microliter</td>
			<td>USA Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-d-lysine coated glass bottomed culture dish</td>
			<td>Mattek</td>
			<td>P35GC-0-10-C</td>
			<td>to plate neurons for culture</td>
		</tr>
		<tr>
			<td>Quick change platform, heated base, for 35 mm culture dishes</td>
			<td>Warner Instruments</td>
			<td>64-0375</td>
			<td></td>
		</tr>
		<tr>
			<td>Reference Cell</td>
			<td>World Precision Instruments</td>
			<td>RC1T</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel blade</td>
			<td>Miltex</td>
			<td>4-315</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel Handle</td>
			<td>Fine Science Tools</td>
			<td>10003-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Scientific Scale</td>
			<td>Mettler Toledo</td>
			<td>XS64</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological Pipettes (10, 25) milliliter</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone Grease Kit (for sealing coverglass and chamber)</td>
			<td>Warner Instruments</td>
			<td>64-0378</td>
			<td></td>
		</tr>
		<tr>
			<td>Small Animal Guillotine</td>
			<td>Kent Scientific</td>
			<td>DCAP</td>
			<td></td>
		</tr>
		<tr>
			<td>Small animal guillotine</td>
			<td>Kent Scientific</td>
			<td>DCAP</td>
			<td>for decapitation if dissecting rats older than P15.</td>
		</tr>
		<tr>
			<td>Stereo Dissection Microscope&#160;</td>
			<td>Zeiss</td>
			<td>Stemi 2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Straight surgical scissors</td>
			<td>Fine Science Tools</td>
			<td>14060-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe (3, 10, 30) milliliter</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Sigma Aldrich</td>
			<td>T1426</td>
			<td>one out of three enzyme to digest tissue</td>
		</tr>
		<tr>
			<td>Tuberculin syringe&#160;</td>
			<td>Covidien</td>
			<td>8881500105</td>
			<td>for delivering euthanasia solution by intraperitoneal injection</td>
		</tr>
		<tr>
			<td>Vannas Spring Scissor, 2.5 mm Cutting Edge</td>
			<td>Fine Science Tools</td>
			<td>15000-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Volumetric flask, 1000 milliliter</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex</td>
			<td>VWR</td>
			<td>945300</td>
			<td></td>
		</tr>
		<tr>
			<td>Water, sterile u ltrapure, R&#62;18.18 megaOhms cm (e.g., filtered by a Millipore-Sigma water purification system)</td>
			<td>Millipore-Sigma</td>
			<td>CDUFBI001</td>
			<td></td>
		</tr>
	</tbody>
</table>

isolating and culturing vestibular and spiral ganglion somata from neonatal rodents for patch-clamp recordings

The compact morphology of isolated and cultured inner ear ganglion neurons allows for detailed characterizations of the ion channels and neurotransmitter receptors that contribute to cell diversity across this population. This protocol outlines the steps necessary for successful dissecting, dissociating, and short-term culturing of the somata of inner ear bipolar neurons for the purpose of patch-clamp recordings. Detailed instructions for preparing vestibular ganglion neurons are provided with the necessary modifications needed for plating spiral ganglion neurons. The protocol includes instructions for performing whole-cell patch-clamp recordings in the perforated-patch configuration. Example results characterizing the voltage-clamp recordings of hyperpolarization-activated cyclic nucleotide-gated (HCN)-mediated currents highlight the stability of perforated-patch recording configuration in comparison to the more standard ruptured-patch configuration. The combination of these methods, isolated somata plus perforated-patch-clamp recordings, can be used to study cellular processes that require long, stable recordings and the preservation of intracellular milieu, such as signaling through G-protein coupled receptors.

Running voltage-clamp protocols by applying families of voltage steps reveals the voltage-dependent activation of a variety of different families of currents. Representative examples of whole-cell currents evoked from a VGN and adapted from published recordings13 are shown in Figure 1A,B. Applying depolarizing voltages (Figure 1B) activates an inward current (negative by convention) that activates and inactivates very rap...

Watch this Scientific Journal Video about Isolating and Culturing Vestibular and Spiral Ganglion Somata from Neonatal Rodents for Patch-Clamp Recordings at JoVE.com

Isolating and Culturing Vestibular and Spiral Ganglion Somata from Neonatal Rodents for Patch-Clamp Recordings

Presented here are methods providing detailed instructions for dissecting, dissociating, culturing, and patch-clamp recording from vestibular ganglion and spiral ganglion neurons of the inner ear.

The compact morphology of isolated and cultured inner ear ganglion neurons allows for detailed characterizations of the ion channels and neurotransmitter ...

Many ion channels and neurotransmitter receptors that are found at the terminals of auditory and vestibular afferent neurons are also found at their cell bodies. Cultures of isolated cell bodies can be studied in vitro to understand how these ion channels and receptors influence the responses of the neurons. The compact morphology of the cell bodies allows for high quality electrical recordings to characterize the voltage-dependent properties of the ion channels and neurotransmitter receptors.Moreover, easy access to a wide variety of cell types allows for high throughput by a physical analysis of cell diversity. The procedures will be demonstrated by graduate student Katherine Regalado, along with postdoctoral fellows, Dr.Daniel Bronson and Nathaniel Nowak from my laboratory. To begin hold a glass pasture pipette to the flame of a Bunsen burner to prepare tritration pipettes for cell dissociation.Once the glass tip begins to melt, stretch the glass out to the desired tip diameter. Pull one end of the pipette away from the flame to create a small bend. Place the bent pipette under a microscope.Using a scoring tile, score and break the glass at the desired diameter. Pass the pipette tip over the top of the burner flame. This will quickly polish the rough edges near the tip.Scoop out the brain of the euthanized mouse using closed surgical scissors. Sever and remove the cranial nerve to completely detach the brain from the skull. Starting at the back of the head, pull the clear membranous material off with forceps, and then cut the top of the skull out using surgical scissors.Remove the excess tissue from the back of the head and neck to make the dissection area and otic capsule cleaner and easier to access. Transfer the tissue to a second Petri dish with fresh L-15 solution. Then locate the otic capsule and the auditory, superior, vestibular, and inferior vestibular nerves.Separate the superior and inferior ganglia using small spring scissors and cut away the auditory nerve. Using a scalpel, gently shave off the bony ridge to weaken the bony area under which the nerve dives into the bony capsule. Carefully remove the debris with a scalpel, exposing the entire swollen portion of the ganglion.Use the fine spring scissors to cut and separate the ganglion from the peripheral nerve branch that is diving toward the utricle. Remove the superior ganglion using fine forceps and transfer it to a 35-millimeter Petri dish with fresh L-15 solution. After preheating the enzyme solution, pour the enzyme mixture into a 35-millimeter Petri dish and place it in a 37 degrees Celsius incubator for 10 to 15 minutes.Clean the ganglion using fine forceps and small spring scissors by removing bone, excess tissue, nerve fibers, and any other superfluous structures. Take care to minimize the removal of any ganglionic tissue. Transfer the cleaned ganglia into the preheated enzyme solution and place it back in the incubator for 10 to 40 minutes.Then transfer the ganglia to the 35-millimeter Petri dish with fresh L-15 solution. After two to three minutes, transfer the ganglia to another 35-millimeter Petri dish filled with filtered culture media. Transfer approximately 150 microliters of filtered culture media onto a coated glass bottom dish.Then, transfer the desired number of ganglia to the cover slip. Draw a small amount of culture media from the culture dish and rinse the tritration pipette with medium to prevent the tissue from sticking to the sides of the glass pipette. Triturate by gently and repeatedly passing the tissue through the pipette until the ganglia are sufficiently dissociated.After five minutes, check under a light microscope to see if the cells have settled on the cover slip. Carefully place a culture dish into a 37-degree Celsius incubator for 12 to 24 hours. Next, locate the otic capsule after bisecting the head and extract it from the skull by chipping away at the edges using forceps.The spiral portion of the otic capsule houses the cochlea with the organ of Corti. Chip away at the bone, overlying the cochlear turns with fine forceps parallel to the curve of the bone. Use small spring scissors to sever the modiolus at the base of the cochlea to free it from the rest of the otic capsule.Cut the organ of Corti into two or three turns using small spring scissors such that it lays flat, and excise the modiolus from each turn. Remove the stria vascularis by pinching the stria at the base with fine forceps. Unwind around the spiral and up to the apex to peel it free from the organ of Corti.Remove the spiral ganglion by cutting at the edge of where the spiral ganglion neuron fiber tracts project toward the hair cells and then clean the ganglion as shown earlier. After enzymatically treating the spiral ganglion, tritrate the spiral ganglion in the culture medium supplemented with N2 and B27. Place the culture dish containing the dissociated ganglia in a 37-degree Celsius, 5%carbon dioxide incubator for 12 to 24 hours.Dip the tip of the pipette into the clean solution of the culture dish to fill it with a clean solution that does not contain amphotericin. Fill the back of the pipette with the internal solution containing amphotericin. Dip the tip of the pipette back into the clean solution of the culture dish while the amphotericin slowly enters the tip from the back of the pipette.Next, finish filling the pipette with the amphotericin solution of to two-thirds of the pipette. Lower the pipette into the bath of the recording chamber and locate the pipette tip in the middle of the field of view. Ensure that the tip is free of air bubbles or other debris.Position the pipette close to the membrane and land firmly on the center of the cell. Apply negative pressure or suction using a syringe or mouth pipette. Turn on the holding potential of minus 60 millivolts.The seal resistance should increase until it passes a giga ohm. Once a giga ohm seal forms, release the negative pressure. Before tyrosine begins to work, the input resistance slowly decreases, and the current flowing in response to the five millivolts voltage step, progressively increases as the amphotericin enters the membrane.The representative examples of whole cell currents evoked from a vestibular ganglion neuron are shown in this figure. The net inward sodium currents are identified here by their transient activation and inactivation. The net outward currents are carried largely by potassium ions and have much slower activation and inactivation kinetics than sodium currents.The hyperpolarization activated cyclic nucleotide gated currents, or HCN currents, are activated by a family of long duration hyperpolarizing voltages. The stability of ion channel characterization in the perforated patch at different time points during recording is shown in this figure. The voltage dependent activation curves of HCN currents were measured in a perforated patch configuration.The curve has a sigmoidal shape and was stable throughout a long recording. The relative instability of the ruptured patch mode is illustrated by non-overlapping sigmoidal curves from different time points. The activation curves of HCN currents during a ruptured patch configuration are shown here.The firing patterns in five vestibular ganglion somara, five spiral ganglion neurons, and the corresponding current steps are shown here. This heterogeneity in firing patterns reflects a fundamental diversity in the composition of underlying sodium and potassium channels in both vestibular ganglion neurons and spiral ganglion neurons. To maximize cell survival during this procedure, avoid forming air bubbles, do not overwork the tissue, and allow cells to settle before placing samples into the incubator.Perforated patch clamp enables the study of ion channels that are modulated by cytosolic second messengers, which is critical for investigating the effects of efferent neurotransmitters on ganglion neurons. Patch clamp recordings of these bipolar neurons have been instrumental in revealing how biophysical diversity contributes to functional diversity in sensory neurons.

isolating-culturing-vestibular-spiral-ganglion-somata-from-neonatal

Research

JoVE Journal

Neuroscience

Patch Clamp Recordings from Mouse Retinal Neurons in a Dark-adapted Slice Preparation

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of intracellular events that lead to closure of cyclic-nucleotide-gated channels in the cell membrane. The resulting change in membrane potential leads in turn to reductions in the amount of neurotransmitter release from both rod and cone synaptic terminals. To measure how the light-evoked change in photoreceptor membrane potential leads to downstream activity in the retina, scientists have made electrophysiological recordings from retinal slice preparations for decades1,2. In the past these slices have been cut manually with a razor blade on retinal tissue that is attached to filter paper; in recent years another method of slicing has been developed whereby retinal tissue is embedded in low gelling temperature agar and sliced in cool solution with a vibrating microtome3,4. This preparation produces retinal slices with less surface damage and very robust light-evoked responses. Here we document how this procedure can be done under infrared light to avoid bleaching the visual pigment.

Here we describe a procedure for generating dark-adapted slices of the mouse retina for electrophysiological recordings.

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of ...

Paired Patch Clamp Recordings from Motor-neuron and Target Skeletal Muscle in Zebrafish

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target muscle. This is a direct consequence of the accessibility to both cell types and ability to visually distinguish the single segmental CaP motor-neuron on the basis of morphology and location. This video demonstrates the microscopic methods used to identify a CaP motor-neuron and target muscle cells as well as the methodologies for recording from each cell type. Identification of the CaP motor-neuron type is confirmed by either dye filling or by the biophysical features such as action potential waveform and cell input resistance. Motor-neuron recordings routinely last for one hour permitting long-term recordings from multiple different target muscle cells. Control over the motor-neuron firing pattern enables measurements of the frequency-dependence of synaptic transmission at the neuromuscular junction. Owing to a large quantal size and the low noise provided by whole cell voltage clamp, all of the unitary events can be resolved in muscle. This feature permits study of basic synaptic properties such as release properties, vesicle recycling, as well as synaptic depression and facilitation. The advantages offered by this in vivo preparation eclipse previous neuromuscular model systems studied wherein the motor-neurons are usually stimulated by extracellular electrodes and the muscles are too large for whole cell patch clamp. The zebrafish preparation is amenable to combining electrophysiological analysis with a wide range of approaches including transgenic lines, morpholino knockdown, pharmacological intervention and in vivo imaging. These approaches, coupled with the growing number of neuromuscular disease models provided by mutant lines of zebrafish, open the door for new understanding of human neuromuscular disorders.

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target skeletal muscle. This video demonstrates the microscopic methods used to identify a segmental CaP motor-neuron and target muscle cells as well as the methodologies for recording from each cell type.

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target muscle.  ...

Isolating Nasal Olfactory Stem Cells from Rodents or Humans

The olfactory mucosa, located in the nasal cavity, is in charge of detecting odours. It is also the only nervous tissue that is exposed to the external environment and easily accessible in every living individual. As a result, this tissue is unique for anyone aiming to identify molecular anomalies in the pathological brain or isolate adult stem cells for cell therapy. 
Molecular abnormalities in brain diseases are often studied using nervous tissue samples collected post-mortem. However, this material has numerous limitations. In contrast, the olfactory mucosa is readily accessible and can be biopsied safely without any loss of sense of smell1. Accordingly, the olfactory mucosa provides an "open window" in the adult human through which one can study developmental (e.g. autism, schizophrenia)2-4 or neurodegenerative (e.g. Parkinson, Alzheimer) diseases4,5. Olfactory mucosa can be used for either comparative molecular studies4,6 or in vitro experiments on neurogenesis3,7.
The olfactory epithelium is also a nervous tissue that produces new neurons every day to replace those that are damaged by pollution, bacterial of viral infections. This permanent neurogenesis is sustained by progenitors but also stem cells residing within both compartments of the mucosa, namely the neuroepithelium and the underlying lamina propria8-10. We recently developed a method to purify the adult stem cells located in the lamina propria and, after having demonstrated that they are closely related to bone marrow mesenchymal stem cells (BM-MSC), we named them olfactory ecto-mesenchymal stem cells (OE-MSC)11.
Interestingly, when compared to BM-MSCs, OE-MSCs display a high proliferation rate, an elevated clonogenicity and an inclination to differentiate into neural cells. We took advantage of these characteristics to perform studies dedicated to unveil new candidate genes in schizophrenia and Parkinson's disease4. We and others have also shown that OE-MSCs are promising candidates for cell therapy, after a spinal cord trauma12,13, a cochlear damage14 or in an animal models of Parkinson's disease15 or amnesia16.
In this study, we present methods to biopsy olfactory mucosa in rats and humans. After collection, the lamina propria is enzymatically separated from the epithelium and stem cells are purified using an enzymatic or a non-enzymatic method. Purified olfactory stem cells can then be either grown in large numbers and banked in liquid nitrogen or induced to form spheres or differentiated into neural cells. These stem cells can also be used for comparative omics (genomic, transcriptomic, epigenomic, proteomic) studies.

We describe here a method for biopsying olfactory mucosa from rat and human nasal cavities. These biopsies can be used for either identifying molecular anomalies in brain diseases or isolating multipotent adult stem cells that can be utilized for cell transplantation in animal models of brain trauma/disease.

The olfactory mucosa, located in the nasal cavity, is in charge of detecting odours. It is also the only nervous tissue that is exposed to the external ...

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 Recordings in Inner Ear Hair Cells Isolated from Zebrafish

Patch clamp analyses of the voltage-gated channels in sensory hair cells isolated from a variety of species have been described previously1-4 but this video represents the first application of those techniques to hair cells from zebrafish. Here we demonstrate a method to isolate healthy, intact hair cells from all of the inner ear end-organs: saccule, lagena, utricle and semicircular canals. Further, we demonstrate the diversity in hair cell size and morphology and give an example of the kinds of patch clamp recordings that can be obtained. The advantage of the use of this zebrafish model system over others stems from the availability of zebrafish mutants that affect both hearing and balance. In combination with the use of transgenic lines and other techniques that utilize genetic analysis and manipulation, the cell isolation and electrophysiological methods introduced here should facilitate greater insight into the roles hair cells play in mediating these sensory modalities.

The purpose of this video is to demonstrate procedures for obtaining healthy, intact hair cells from the inner ear organs of adult zebrafish and then using them for patch clamp studies aimed at characterizing the biophysical properties of their voltage-gated channels.

Patch  clamp analyses of the voltage-gated channels in sensory hair cells isolated  from a variety of species have been described previously1-4 but this  ...

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes

Mitochondria are involved in many important cellular functions including metabolism, survival1, development and, calcium signaling2. Two of the most important mitochondrial functions are related to the efficient production of ATP, the energy currency of the cell, by oxidative phosphorylation, and the mediation of signals for programmed cell death3.
The enzyme primarily responsible for the production of ATP is the F1FO-ATP synthase, also called ATP synthase4-5. In recent years, the role of mitochondria in apoptotic and necrotic cell death has received considerable attention. In apoptotic cell death, BCL-2 family proteins such as Bax enter the mitochondrial outer membrane, oligomerize and permeabilize the outer membrane, releasing pro-apoptotic factors into the cytosol6. In classic necrotic cell death, such as that produced by ischemia or excitotoxicity in neurons, a large, poorly regulated increase in matrix calcium contributes to the opening of an inner membrane pore, the mitochondrial permeability transition pore or mPTP. This depolarizes the inner membrane and causes osmotic shifts, contributing to outer membrane rupture, release of pro-apoptotic factors, and metabolic dysfunction. Many proteins including Bcl-xL7 interact with F1FO ATP synthase, modulating its function. Bcl-xL interacts directly with the beta subunit of F1FO ATP synthase, and this interaction decreases a leak conductance within the F1FOATPasecomplex, increasing the net transport of H+ by F1FO during F1FO ATPase activity8 and thereby increasing mitochondrial efficiency. To study the activity and modulation of the ATP synthase, we isolated from rodent brain submitochondrial vesicles (SMVs) containing F1FO ATPase. The SMVs retain the structural and functional integrity of the F1FO ATPase as shown in Alavian et al. Here, we describe a method that we have used successfully for the isolation of SMVs from rat brain and we delineate the patch clamp technique to analyze channel activity (ion leak conductance) of the SMVs.

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes

A method to isolate submitochondrial vesicles enriched in F1FO ATP synthase complexes from rat brain is described. These vesicles allow the study of the activity of F1FO ATPase complex and its modulation using the technique of patch clamp recording.

Mitochondria are involved in many important cellular  functions including metabolism, survival1, development and, calcium signaling2. Two of the most ...

Isolation of Sensory Neurons of Aplysia californica for Patch Clamp Recordings of Glutamatergic Currents

The marine gastropod mollusk Aplysia californica has a venerable history as a model of nervous system function, with particular significance in studies of learning and memory. The typical preparations for such studies are ones in which the sensory and motoneurons are left intact in a minimally dissected animal, or a technically elaborate neuronal co-culture of individual sensory and motoneurons. Less common is the isolated neuronal preparation in which small clusters of nominally homogeneous neurons are dissociated into single cells in short term culture. Such isolated cells are useful for the biophysical characterization of ion currents using patch clamp techniques, and targeted modulation of these conductances. A protocol for preparing such cultures is described. The protocol takes advantage of the easily identifiable glutamatergic sensory neurons of the pleural and buccal ganglia, and describes their dissociation and minimal maintenance in culture for several days without serum.

Isolation of Sensory Neurons of Aplysia californica for Patch Clamp Recordings of Glutamatergic Currents

We describe the dissection of the nervous system of the marine sea hare Aplysia after anesthesia, the isolation of neurons for short term-tissue culture, and recordings of single cell ion currents via the patch clamp technique.

The marine gastropod mollusk Aplysia californica has a venerable  history as a model of nervous system function, with particular significance in  studies ...

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 ...

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 ...

Electrophysiological and Morphological Characterization of Neuronal Microcircuits in Acute Brain Slices Using Paired Patch-Clamp Recordings

The combination of patch clamp recordings from two (or more) synaptically coupled neurons (paired recordings) in acute brain slice preparations with simultaneous intracellular biocytin filling allows a correlated analysis of their structural and functional properties. With this method it is possible to identify and characterize both pre- and postsynaptic neurons by their morphology and electrophysiological response pattern. Paired recordings allow studying the connectivity patterns between these neurons as well as the properties of both chemical and electrical synaptic transmission. Here, we give a step-by-step description of the procedures required to obtain reliable paired recordings together with an optimal recovery of the neuron morphology. We will describe how pairs of neurons connected via chemical synapses or gap junctions are identified in brain slice preparations. We will outline how neurons are reconstructed to obtain their 3D morphology of the dendritic and axonal domain and how synaptic contacts are identified and localized. We will also discuss the caveats and limitations of the paired recording technique, in particular those associated with dendritic and axonal truncations during the preparation of brain slices because these strongly affect connectivity estimates. However, because of the versatility of the paired recording approach it will remain a valuable tool in characterizing different aspects of synaptic transmission at identified neuronal microcircuits in the brain.

Patch-clamp recordings and simultaneous intracellular biocytin filling of synaptically coupled neurons in acute brain slices allow a correlated analysis of their structural and functional properties. The aim of this protocol is to describe the essential technical steps of electrophysiological recording from neuronal microcircuits and their subsequent morphological analysis.

The combination of patch clamp recordings from two (or more) synaptically coupled neurons (paired recordings) in acute brain slice preparations with ...