Name: recording synaptic plasticity in acute hippocampal slices maintained in a small-volume recycling-, perfusion-, and submersion-type chamber system
Uploaded: 2018-01-01T13:00:00
Description: Watch this Scientific Journal Video about Recording Synaptic Plasticity in Acute Hippocampal Slices Maintained in a Small-volume Recycling-, Perfusion-, and Submersion-type Chamber System at JoVE.com

W.W. conducted, analyzed, and designed the experiments and wrote the manuscript. D.X. and C.P. assisted in figure preparation and conducted the experiments. This work was supported by NSFC (31320103906) and 111 Project (B16013) to T.B.

The animals were maintained in accordance with the established standards of animal care and procedures of the Institutes of Brain Science and State Key Laboratory of Medical Neurobiology of Fudan University, Shanghai, China.
1. Solution Preparation
NOTE: See the Table of Materials.
<ol>
	<li>Prepare the slicing buffer (modified Gey&#39;s solution): 92 mM NaCl, 2.5 mM KCl, 1.25 mM NaH2PO4, 30 mM NaHCO3, 25 mM glucose, 20 mM HEPES, 3 mM Na+-pyruva...

<ol>
	<li>McIlwain, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metabolic+response+in+vitro+to+electrical+stimulation+of+sections+of+mammalian+brain.">Metabolic response in vitro to electrical stimulation of sections of mammalian brain.</a> Biochem J. 48 (4), (1951).</li><li>McIlwain, H., Richards, C. D., Somerville, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Responses+in+vitro+from+the+piriform+cortex+of+the+rat,+and+their+susceptibility+to+centrally-acting+drugs.">Responses in vitro from the piriform cortex of the rat, and their susceptibility to centrally-acting drugs.</a> J Neurochem. 14 (9), 937-938 (1967).</li><li>Yamamoto, C., McIlwain, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+activities+in+thin+sections+from+the+mammalian+brain+maintained+in+chemically-defined+media+in+vitro.">Electrical activities in thin sections from the mammalian brain maintained in chemically-defined media in vitro.</a> J Neurochem. 13 (12), 1333-1343 (1966).</li><li>Andersen, P., Bliss, T. V., Lomo, T., Olsen, L. I., Skrede, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lamellar+organization+of+hippocampal+excitatory+pathways.">Lamellar organization of hippocampal excitatory pathways.</a> Acta Physiol Scand. 76 (1), 4-5 (1969).</li><li>Skrede, K. K., Westgaard, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+transverse+hippocampal+slice:+a+well-defined+cortical+structure+maintained+in+vitro.">The transverse hippocampal slice: a well-defined cortical structure maintained in vitro.</a> Brain Res. 35 (2), 589-593 (1971).</li><li>Kirov, S. A., Sorra, K. E., Harris, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slices+have+more+synapses+than+perfusion-fixed+hippocampus+from+both+young+and+mature+rats.">Slices have more synapses than perfusion-fixed hippocampus from both young and mature rats.</a> J Neurosci. 19 (8), 2876-2886 (1999).</li><li>Schwartzkroin, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characteristics+of+CA1+neurons+recorded+intracellularly+in+the+hippocampal+in+vitro+slice+preparation.">Characteristics of CA1 neurons recorded intracellularly in the hippocampal in vitro slice preparation.</a> Brain Res. 85 (3), 423-436 (1975).</li><li>Schwartzkroin, P. A., Wester, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-lasting+facilitation+of+a+synaptic+potential+following+tetanization+in+the+in+vitro+hippocampal+slice.">Long-lasting facilitation of a synaptic potential following tetanization in the in vitro hippocampal slice.</a> Brain Res. 89 (1), 107-119 (1975).</li><li>Reymann, K. G., Frey, J. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+late+maintenance+of+hippocampal+LTP:+requirements,+phases,+'synaptic+tagging',+'late-associativity'+and+implications.">The late maintenance of hippocampal LTP: requirements, phases, 'synaptic tagging', 'late-associativity' and implications.</a> Neuropharm. 52 (1), 24-40 (2007).</li><li>Bliss, T. V., Collingridge, G. L., Morris, R. 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Although interface slice chambers exhibit more robust synaptic responses25,26,27,28, submersion chambers provide additional convenience for patch-clamp recording and fluorescence imaging. Thus, we have described several aspects of field potential recordings in acute hippocampal slices using a commercial submersion slice chamber that can easily be extended to the imaging of fluorescence probes i...

In 1951, the first-reported acute brain slice experiments were conducted1. In 1971, after successful in vitro recordings from the piriform cortex2,3 and the discovery that hippocampal neurons are interconnected transversely along the septotemporal axis of the hippocampus4, one of the first in vitro recordings of hippocampal neuronal activity was achieved5. The similarity of the neurophysiological or neurostructural parameters of neurons under in vivo and in vitro conditions are still the subject of some debate6, but in 1975, Schwartzkroin7 indicated that the basal properties of neurons are maintained in vitro and that high-frequency stimulation (i.e., tetanization) of afferents in the hippocampal formation induces a long-lasting facilitation of synaptic potentials8. Electrophysiological recording of neuronal activity in vitro greatly expanded the study of the cellular mechanisms of activity-dependent synaptic plasticity9,10, which had been discovered in 1973 by Bliss et al.11 in in vivo experiments with rabbits.
The study of neuronal activity or signaling pathways in brain slices, and especially in acute hippocampal slices, is now a standard tool. However, surprisingly, in vitro experiments have yet to be standardized, as evidenced by the multiple approaches that still exist for the preparation and maintenance of acute hippocampal slices. Reid et al. (1988)12 reviewed the methodological challenges for the maintenance of acute brain slices in different types of slice chambers and the choices of bathing medium, pH, temperature, and oxygen level. These parameters are still difficult to control in the recording chamber due to the custom-made elements of in vitro slice-recording setups. Publications can be found that might help to overcome some of the methodological challenges and that describe new types of submersion slice chambers, such as an interstitial 3D microperfusion system13, a chamber with enhanced laminar flow and oxygen supply14, a system with computerized temperature control15, and a multi-chamber recording system16. Since these chambers are not easy to build, most scientists rely on commercially available slice chambers. These chambers can be mounted on a microscope system, thus allowing for the combination of electrophysiology and fluorescence imaging17,18,19. Since these chambers keep the brain slices submerged in artificial cerebrospinal fluid (aCSF), a high flow rate of the buffer solution needs to be maintained, increasing the expense of drug application. To this end, we have incorporated a recycling perfusion system with outflow-carbogenation that provides sufficient stability for the long-term recording of field potentials in a submersion slice chamber using a relatively small aCSF volume. In addition, we summarized how the use of this experimental carbogenation/perfusion system affects the outcome of activity-dependent synaptic plasticity10 and how inhibition of eukaryotic elongation factor-2 kinase (eEF2K) modulates synaptic transmission20.

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			<td height="21" style="width:311px;height:21px;">Reagents required</td>
			<td style="width:244px;"></td>
			<td style="width:179px;"></td>
			<td style="width:251px;"></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">NaCl</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10019318</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">KCl</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10016318</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">KH2PO4</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10017618</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">MgCl2&#183;6H2O</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10012818</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">CaCl2</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10005861</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">NaHCO3</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10018960</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">Glucose</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10010518</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">NaH2PO4</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">20040718</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">HEPES</td>
			<td style="width:244px;">Sigma</td>
			<td style="width:179px;">H3375</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">Sodium pyruvate</td>
			<td style="width:244px;">Sigma</td>
			<td style="width:179px;">A4043</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">MgSO4</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">20025118</td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:311px;height:27px;">NaOH</td>
			<td style="width:244px;">Sinopharm Chemical Reagent, China</td>
			<td style="width:179px;">10019718</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;"></td>
			<td style="width:244px;"></td>
			<td style="width:179px;"></td>
			<td></td>
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			<td height="21" style="width:311px;height:21px;">Tools and materials for dissection</td>
			<td style="width:244px;"></td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Decapitators</td>
			<td style="width:244px;">Harvard apparatus</td>
			<td style="width:179px;">55-0012</td>
			<td>for rat decapitation</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Bandage Scissors</td>
			<td style="width:244px;">SCHREIBER</td>
			<td style="width:179px;">12-4227</td>
			<td>for mouse decapitation</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">double-edge blade</td>
			<td style="width:244px;">Flying Eagle, China</td>
			<td style="width:179px;">74-C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">IRIS Scissors</td>
			<td style="width:244px;">RWD, China</td>
			<td style="width:179px;">S12003-09</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Bone Rongeurs</td>
			<td style="width:244px;">RWD, China</td>
			<td style="width:179px;">S22002-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Spoon</td>
			<td style="width:244px;">Hammacher&#160;</td>
			<td style="width:179px;">HSN 152-13</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">dental cement spatula</td>
			<td style="width:244px;">Hammacher&#160;</td>
			<td style="width:179px;">HSN 016-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">dental double end excavator</td>
			<td style="width:244px;">Blacksmith Surgical, USA</td>
			<td style="width:179px;">BS-415-017</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Vibrating Microtome</td>
			<td style="width:244px;">Leica, Germany</td>
			<td style="width:179px;">VT1200S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">surgical blade&#160;</td>
			<td style="width:244px;">RWD, China</td>
			<td style="width:179px;">S31023-02</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">surgical holder</td>
			<td style="width:244px;">RWD, China</td>
			<td style="width:179px;">S32007-14</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;"></td>
			<td style="width:244px;"></td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="width:311px;height:42px;">Electrophysiology equipment and materials</td>
			<td style="width:244px;"></td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Vertical Pipette Puller</td>
			<td style="width:244px;">Narishige, Japan</td>
			<td style="width:179px;">PC-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Vibration isolation table</td>
			<td style="width:244px;">Meirits, Japan</td>
			<td style="width:179px;">ADZ-A0806</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">submerged type recording chamber</td>
			<td style="width:244px;">Warner Instruments</td>
			<td style="width:179px;">RC-26GLP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">thermostatic water bath</td>
			<td style="width:244px;">Zhongcheng Yiqi&#65292;China</td>
			<td style="width:179px;">HH-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">4 Axis Micromanipulator</td>
			<td style="width:244px;">Sutter, USA</td>
			<td style="width:179px;">MP-285, MP-225</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Platinum Wire</td>
			<td style="width:244px;">World Precision Instruments</td>
			<td style="width:179px;">PTP406</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Amplifier</td>
			<td style="width:244px;">Molecular Devices, USA</td>
			<td style="width:179px;">Multiclamp 700B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Data Acquisition System</td>
			<td style="width:244px;">Molecular Devices, USA</td>
			<td style="width:179px;">Digidata 1440A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Anaysis software</td>
			<td style="width:244px;">Molecular Devices, USA</td>
			<td style="width:179px;">Clampex 10.2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Fluorescence Microscope</td>
			<td style="width:244px;">Nikon, Japan</td>
			<td style="width:179px;">FN1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">LED light source</td>
			<td style="width:244px;">Lumen Dynamics Group, Canada</td>
			<td style="width:179px;">X-cite 120LED</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">micropipettes</td>
			<td style="width:244px;">Harvard apparatus</td>
			<td style="width:179px;">GC150TF</td>
			<td>extracelluar recording</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">borosilicate micropipettes</td>
			<td style="width:244px;">Sutter, USA</td>
			<td style="width:179px;">BF150-86</td>
			<td>patch clamp</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">tungsten electrode</td>
			<td style="width:244px;">A-M Systems, USA</td>
			<td style="width:179px;">575500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">peristaltic pump</td>
			<td style="width:244px;">Longer, China</td>
			<td style="width:179px;">BT00-300T</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">tubes for peristaltic pump</td>
			<td style="width:244px;">ISMATEC, Wertheim, Germany</td>
			<td style="width:179px;">SC0309</td>
			<td>1x inflow, ID: 1.02mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">tubes for peristaltic pump</td>
			<td style="width:244px;">ISMATEC, Wertheim, Germany</td>
			<td style="width:179px;">SC0319</td>
			<td>2x tubes for outflow, ID: 2.79 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">CCD camera</td>
			<td style="width:244px;">PCO, Germany</td>
			<td style="width:179px;">pco.edge sCMOS</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">lens cleaning paper</td>
			<td style="width:244px;">Kodak</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">50 ml conical centrifuge tube</td>
			<td style="width:244px;">Thermo scientific</td>
			<td style="width:179px;">339652</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Prechamber</td>
			<td style="width:244px;">Warner Instruments</td>
			<td style="width:179px;">BSC-PC</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Inline heater</td>
			<td style="width:244px;">Warner Instruments</td>
			<td style="width:179px;">SF-28</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="width:311px;height:21px;">Temperature Controller</td>
			<td style="width:244px;">Warner Instruments</td>
			<td style="width:179px;">TC-324B</td>
			<td></td>
		</tr>
	</tbody>
</table>

recording synaptic plasticity in acute hippocampal slices maintained in a small-volume recycling-, perfusion-, and submersion-type chamber system

Even though experiments on brain slices have been in use since 1951, problems remain that reduce the probability of achieving a stable and successful analysis of synaptic transmission modulation when performing field potential or intracellular recordings. This manuscript describes methodological aspects that might be helpful in improving experimental conditions for the maintenance of acute brain slices and for recording field excitatory postsynaptic potentials in a commercially available submersion chamber with an outflow-carbogenation unit. The outflow-carbogenation helps to stabilize the oxygen level in experiments that rely on the recycling of a small buffer reservoir to enhance the cost-efficiency of drug experiments. In addition, the manuscript presents representative experiments that examine the effects of different carbogenation modes and stimulation paradigms on the activity-dependent synaptic plasticity of synaptic transmission.

In the protocol section, we described the preparation of acute hippocampal slices from the ventral and intermediate part of the hippocampal formation (Figure 1) of male C57BL/6 mice and male Wistar rats (5-8 weeks). The position of the hemispheres on the slicer platform helps to keep them stable and removes the need of stabilization with agar or agarose. The perfusion system itself is based on a peristaltic pump operated on high rotation to give the required ...

Watch this Scientific Journal Video about Recording Synaptic Plasticity in Acute Hippocampal Slices Maintained in a Small-volume Recycling-, Perfusion-, and Submersion-type Chamber System at JoVE.com

Recording Synaptic Plasticity in Acute Hippocampal Slices Maintained in a Small-volume Recycling-, Perfusion-, and Submersion-type Chamber System

This protocol describes the stabilization of the oxygen level in a small volume of recycled buffer and methodological aspects of recording activity-dependent synaptic plasticity in submerged acute hippocampal slices.

Even though experiments on brain slices have been in use since 1951, problems remain that reduce the probability of achieving a stable and successful ...

The overall goal of this procedure is to provide a method to ensure simplified means of carbogenation of small-volume recycling ACSF and to achieve long-term recordings of field potentials using a recording chamber mounted on a fluorescence microscope. This method can help us answer the key questions in the field of neuroplasticities relating to the underlying lignin pathways that regulates the synaptic transmission and formation of memory in a cellular mode of learning and memories. The main advantage of this technique is that it helps to stabilize the oxygen level of a small bio reservoir to enhance the cost efficiency of the experiments using specific antagonists or agonists.The preparation of the acute hippocampus slices is demonstrated by the PhD students, Xia and Weiguang of our laboratory. To begin this procedure, use a cold surgical blade to dissect a piece of the dorsal cortex at a 70 degree angle along the dorsal edge of each hemisphere. With a cold dental cement spatula, transfer each hemisphere to a piece of filter paper to briefly dry the surface.Mount the two hemispheres with freshly cut surfaces on the ice cold slicing platform using fast-acting adhesive glue so the caudal end of the hemispheres face the razor blade. Next, place the slicing platform into the cooling chamber of a vibratome. Fill the chamber with the slicing buffer at two to four degrees Celsius and carbogenate it.After that, cut 350 micrometer slices using adequate vibrotome settings. Isolate the hippocampal formation from the subiculum and the entorhinal cortices using two injection cannulas as scissors. Remove the bubbles from the slice-holding mesh of the previously prepared incubation chamber using a pasteur pipette.Then, transfer the slices that have some transparency at the stratum pyramidal from the slicing platform on the mesh of the incubation chamber with a large-mouth pasteur pipette. In this step, add a three-way tube connector to the outflow of the recycling system. Connect the middle arm of the three-way tube connector to a carbogen supply tube and regulate the flow rate with an airflow meter.After that, add a second three-way tube connector to the inflow of the recycling system. Connect the middle arm to the tube facing the inline heater, the upper arm to a thin silicone tube, and the lower arm to the inflow tube from the reservoir. Then, place a tube squeezer on a thin silicone tube at a position along the tube where the pulsation of the ACSF in the slice chamber generated by the peristolic pump is at its minimum.Now, presoak a small piece of lens-cleaning paper and a nylon mesh fixed on a U-shaped platinum wire in the submersion slice chamber for a few minutes. After that, remove the U-shaped platinum wire. Switch off the recycling and place a slice on the lens-cleaning paper.Then, immediately place the slice-holding mesh on top of the slice. Switch on the pump and let the slice equilibrate for 30 minutes without dipping the objective into ACSF. In the meantime, fill the recording electrode with ACSF and mount it into the pipette holder.Check the insulation of the metal stimulation electrode by placing it into sodium bicarbonate solution. Connect the electrode to the negative pole of a DC voltage generator and observe the formation of bubbles at the tip under a dissection microscope. Next, place the tested apoxy-insulated tungsten stimulation electrode in the manipulator holder and the reference wire in the slice chamber.Add a second reference electrode to the chamber and connect it to the reference socket of the head stage of the recording electrode. In the amplifier control software, click on the zero clamp mode box, then double click the output gain list box. Choose a gain of 100, double click the high pass filter box vessel, choose three kilohertz, and double click the low pass filter list box AC to choose 0.1 hertz.In the recording software, click on acquire, open protocol. Choose a protocol that has the settings allowing for episodic stimulations and the digitalization of amplified potentials at 10 to 20 kilohertz for 50 to 100 milliseconds and that automatically triggers a stimulus isolator 10 milliseconds after the start of an episodic recording. Place the stimulation and recording electrodes in line and parallel to the stratum pyramidal.Subsequently, click acquire, edit protocol, and choose the trigger tab in the popup window. Click on the trigger source box and choose space bar as the trigger source. Then, click the okay button and click the record button to start the acquisition.In the stimulus isolator software, click on the voltage control box and enter zero. Click the download button. Following that, click on the recording software window and press the space bar.Repeat this cycle by sequentially entering values from 1000 to 8000. Correlate the stimulation strength with FEPSP slope values and determine the stimulation strength required to get 40%of the FEPSP slope maximum. Click the voltage control box and enter the determined value.Then, click the download button. In the recording software, click the stop button and then the acquire menu. Click on edit protocol and choose the trigger tab in the popup window.Afterward, click on the trigger source box and choose the internal timer as the trigger source. Click the okay button, followed by the record button that starts the automatic recording of field potentials every 60 seconds. Click the stop button after 30 to 60 minutes.In the recording software, click acquire, open protocol, and choose the same protocol as the baseline recording. Click the okay button and then click record. Keep automatically running the field potential recordings for two to four hours.When it is finished, click the stop button to terminate the recording. This figure shows the representative recordings of activity-dependent potentiation of synaptic transmission using outflow carbogenation and reservoir carbogenation with the recycling of a small ACSF reservoir. The potentiation was induced after time-point zero by three times 100 hertz per second trains.This figure shows the outflow carbogenation with recycling of a small ACSF reservoir improved the LTD induction in comparison to experiments with reservoir carbogenation only. Once mastered, the slice preparation can be done in five to 10 minutes and a stable field potential recording can also be achieved for many hours if it is performed properly. While attempting this procedure, it is important to adjust your carbogenation level, perfusion speed, the position of the electrodes, and the stimulation stress of your specific equivalence.Following this procedure, other method like the patch clamp, the forensics microscopy can be performed in order to answer the additional questions like the virilization of sap cellular localization of ravin probings in response to the induction of activity-dependent synaptic plasticity. After its development, this technique paves the way for researchers in the field of neuroplasticity to explore activity-dependent synaptic plasticity as a cellular mode of learning and memory in in vitro hippocampal slices of well tab and transgenic mouse genes. After watching this video, you should have a good understanding of how to perform acute slice preparation from the temporal hippocampus and how to obtain stable conditions for long-term recording of synaptic transmissions using a small volume of recycled ACSF.Don't forget that working with animals and chemical compounds can be hazardous and precautions such as wearing gloves and the proper disinfection should always be taken while performing this procedure.

recording-synaptic-plasticity-acute-hippocampal-slices-maintained

Research

JoVE Journal

Neuroscience

Preparation of Oligomeric &beta;-amyloid1-42 and Induction of Synaptic Plasticity Impairment on Hippocampal Slices

Impairment of synaptic connections is likely to underlie the subtle amnesic changes occurring at the early stages of Alzheimer s Disease (AD). &beta;-amyloid (A&beta;), a peptide produced in high amounts in AD, is known to reduce Long-Term Potentiation (LTP), a cellular correlate of learning and memory. Indeed, LTP impairment caused by A&beta; is a useful experimental paradigm for studying synaptic dysfunctions in AD models and for screening drugs capable of mitigating or reverting such synaptic impairments. Studies have shown that A&beta; produces the LTP disruption preferentially via its oligomeric form. Here we provide a detailed protocol for impairing LTP by perfusion of oligomerized synthetic A&beta;1-42 peptide onto acute hippocampal slices. In this video, we outline a step-by-step procedure for the preparation of oligomeric A&beta;1-42. Then, we follow an individual experiment in which LTP is reduced in hippocampal slices exposed to oligomerized A&beta;1-42 compared to slices in a control experiment where no A&beta;1-42 exposure had occurred.

Preparation of Oligomeric &#946;-amyloid1-42 and Induction of Synaptic Plasticity Impairment on Hippocampal Slices

One feature of Alzheimer's Disease is the elevation of A&beta;1-42 peptide. Here we provide a protocol for preparing synthetic A&beta;1-42 oligomers, which impairs hippocampal Long-Term Potentiation, a cellular correlate of memory. This procedure is useful for investigating mechanisms of A&beta;-induced pathology and drug screening.

Impairment of synaptic connections is likely to underlie the subtle amnesic changes occurring at the early stages of Alzheimer s Disease (AD). ...

Preparation of Acute Hippocampal Slices from Rats and Transgenic Mice for the Study of Synaptic Alterations during Aging and Amyloid Pathology

The rodent hippocampal slice preparation is perhaps the most broadly used tool for investigating mammalian synaptic function and plasticity. The hippocampus can be extracted quickly and easily from rats and mice and slices remain viable for hours in oxygenated artificial cerebrospinal fluid. Moreover, basic electrophysisologic techniques are easily applied to the investigation of synaptic function in hippocampal slices and have provided some of the best biomarkers for cognitive impairments. The hippocampal slice is especially popular for the study of synaptic plasticity mechanisms involved in learning and memory. Changes in the induction of long-term potentiation and depression (LTP and LTD) of synaptic efficacy in hippocampal slices (or lack thereof) are frequently used to describe the neurologic phenotype of cognitively-impaired animals and/or to evaluate the mechanism of action of nootropic compounds. This article outlines the procedures we use for preparing hippocampal slices from rats and transgenic mice for the study of synaptic alterations associated with brain aging and Alzheimer's disease (AD)1-3. Use of aged rats and AD model mice can present a unique set of challenges to researchers accustomed to using younger rats and/or mice in their research. Aged rats have thicker skulls and tougher connective tissue than younger rats and mice, which can delay brain extraction and/or dissection and consequently negate or exaggerate real age-differences in synaptic function and plasticity. Aging and amyloid pathology may also exacerbate hippocampal damage sustained during the dissection procedure, again complicating any inferences drawn from physiologic assessment. Here, we discuss the steps taken during the dissection procedure to minimize these problems. Examples of synaptic responses acquired in "healthy" and "unhealthy" slices from rats and mice are provided, as well as representative synaptic plasticity experiments. The possible impact of other methodological factors on synaptic function in these animal models (e.g. recording solution components, stimulation parameters) are also discussed. While the focus of this article is on the use of aged rats and transgenic mice, novices to slice physiology should find enough detail here to get started on their own studies, using a variety of rodent models.

This article outlines procedures for preparing hippocampal slices from rats and transgenic mice for the study of synaptic alterations associated with brain aging and age-related neurodegenerative diseases, such as Alzheimer&#x2019;s disease.

The rodent hippocampal slice preparation is perhaps the most broadly used tool for investigating mammalian synaptic function and plasticity. The ...

Lateral Diffusion and Exocytosis of Membrane Proteins in Cultured Neurons Assessed using Fluorescence Recovery and Fluorescence-loss Photobleaching

Membrane proteins such as receptors and ion channels undergo active trafficking in neurons, which are highly polarised and morphologically complex. This directed trafficking is of fundamental importance to deliver, maintain or remove synaptic proteins.
Super-ecliptic pHluorin (SEP) is a pH-sensitive derivative of eGFP that has been extensively used for live cell imaging of plasma membrane proteins1-2. At low pH, protonation of SEP decreases photon absorption and eliminates fluorescence emission. As most intracellular trafficking events occur in compartments with low pH, where SEP fluorescence is eclipsed, the fluorescence signal from SEP-tagged proteins is predominantly from the plasma membrane where the SEP is exposed to a neutral pH extracellular environment. When illuminated at high intensity SEP, like every fluorescent dye, is irreversibly photodamaged (photobleached)3-5. Importantly, because low pH quenches photon absorption, only surface expressed SEP can be photobleached whereas intracellular SEP is unaffected by the high intensity illumination6-10. 
FRAP (fluorescence recovery after photobleaching) of SEP-tagged proteins is a convenient and powerful technique for assessing protein dynamics at the plasma membrane. When fluorescently tagged proteins are photobleached in a region of interest (ROI) the recovery in fluorescence occurs due to the movement of unbleached SEP-tagged proteins into the bleached region. This can occur via lateral diffusion and/or from exocytosis of non-photobleached receptors supplied either by de novo synthesis or recycling (see Fig. 1). The fraction of immobile and mobile protein can be determined and the mobility and kinetics of the diffusible fraction can be interrogated under basal and stimulated conditions such as agonist application or neuronal activation stimuli such as NMDA or KCl application8,10. 
We describe photobleaching techniques designed to selectively visualize the recovery of fluorescence attributable to exocytosis. Briefly, an ROI is photobleached once as with standard FRAP protocols, followed, after a brief recovery, by repetitive bleaching of the flanking regions. This 'FRAP-FLIP' protocol, developed in our lab, has been used to characterize AMPA receptor trafficking at dendritic spines10, and is applicable to a wide range of trafficking studies to evaluate the intracellular trafficking and exocytosis.

This report describes the use of live cell imaging and photobleach techniques to determine the surface expression, transport pathways and trafficking kinetics of exogenously expressed, pH-sensitive GFP-tagged proteins at the plasma membrane of neurons.

Membrane proteins such as receptors and ion channels undergo active trafficking in neurons, which are highly polarised and morphologically complex. This ...

Dual Electrophysiological Recordings of Synaptically-evoked Astroglial and Neuronal Responses in Acute Hippocampal Slices

Astrocytes form together with neurons tripartite synapses, where they integrate and modulate neuronal activity. Indeed, astrocytes sense neuronal inputs through activation of their ion channels and neurotransmitter receptors, and process information in part through activity-dependent release of gliotransmitters. Furthermore, astrocytes constitute the main uptake system for glutamate, contribute to potassium spatial buffering, as well as to GABA clearance. These cells therefore constantly monitor synaptic activity, and are thereby sensitive indicators for alterations in synaptically-released glutamate, GABA and extracellular potassium levels. Additionally, alterations in astroglial uptake activity or buffering capacity can have severe effects on neuronal functions, and might be overlooked when characterizing physiopathological situations or knockout mice. Dual recording of neuronal and astroglial activities is therefore an important method to study alterations in synaptic strength associated to concomitant changes in astroglial uptake and buffering capacities. Here we describe how to prepare hippocampal slices, how to identify stratum radiatum astrocytes, and how to record simultaneously neuronal and astroglial electrophysiological responses. Furthermore, we describe how to isolate pharmacologically the synaptically-evoked astroglial currents.

The preparation of acute brain slices from isolated hippocampi, as well as the simultaneous electrophysiological recordings of astrocytes and neurons in stratum radiatum during stimulation of schaffer collaterals is described. The pharmacological isolation of astroglial potassium and glutamate transporter currents is demonstrated.

Astrocytes form together with neurons tripartite synapses, where they integrate and modulate neuronal activity. Indeed, astrocytes sense neuronal inputs ...

Paired Whole Cell Recordings in Organotypic Hippocampal Slices

Pair recordings involve simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling not only direct electrophysiological characterization of the synaptic connections between individual neurons, but also pharmacological manipulation of either the presynaptic or the postsynaptic neuron. When carried out in organotypic hippocampal slice cultures, the probability that two neurons are synaptically connected is significantly increased. This preparation readily enables identification of cell types, and the neurons maintain their morphology and properties of synaptic function similar to that in native brain tissue. A major advantage of paired whole cell recordings is the highly precise information it can provide on the properties of synaptic transmission and plasticity that are not possible with other more crude techniques utilizing extracellular axonal stimulation. Paired whole cell recordings are often perceived as too challenging to perform. While there are challenging aspects to this technique, paired recordings can be performed by anyone trained in whole cell patch clamping provided specific hardware and methodological criteria are followed. The probability of attaining synaptically connected paired recordings significantly increases with healthy organotypic slices and stable micromanipulation allowing independent attainment of pre- and postsynaptic whole cell recordings. While CA3-CA3 pyramidal cell pairs are most widely used in the organotypic slice hippocampal preparation, this technique has also been successful in CA3-CA1 pairs and can be adapted to any neurons that are synaptically connected in the same slice preparation. In this manuscript we provide the detailed methodology and requirements for establishing this technique in any laboratory equipped for electrophysiology.

Pair recordings are simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling precise electrophysiological and pharmacological characterization of the synapses between individual neurons. Here we describe the detailed methodology and requirements for establishing this technique in organotypic hippocampal slice cultures in any laboratory equipped for electrophysiology.

Pair recordings involve simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling not only direct ...

Investigation of Synaptic Tagging/Capture and Cross-capture using Acute Hippocampal Slices from Rodents

Synaptic tagging and capture (STC) and cross-tagging are two important mechanisms at cellular level that explain how synapse-specificity and associativity is achieved in neurons within a specific time frame. These long-term plasticity-related processes are the leading candidate models to study the basis of memory formation and persistence at the cellular level. Both STC and cross-tagging involve two serial processes: (1) setting of the synaptic tag as triggered by a specific pattern of stimulation, and (2) synaptic capture, whereby the synaptic tag interacts with newly synthesized plasticity-related proteins (PRPs). Much of the understanding about the concepts of STC and cross-tagging arises from the studies done in CA1 region of the hippocampus and because of the technical complexity many of the laboratories are still unable to study these processes. Experimental conditions for the preparation of hippocampal slices and the recording of stable late-LTP/LTD are extremely important to study synaptic tagging/cross-tagging. This video article describes the experimental procedures to study long-term plasticity processes such as STC and cross-tagging in the CA1 pyramidal neurons using stable, long-term field-potential recordings from acute hippocampal slices of rats.

This video article describes experimental procedures to study long-term plasticity and its associative processes such as synaptic tagging, capture and cross-tagging in the CA1 pyramidal neurons using acute hippocampal slices from rodents.

Synaptic tagging and capture (STC) and cross-tagging are two important mechanisms at cellular level that explain how synapse-specificity and associativity ...

Measuring Synaptic Vesicle Endocytosis in Cultured Hippocampal Neurons

During endocytosis, fused synaptic vesicles are retrieved at nerve terminals, allowing for vesicle recycling and thus the maintenance of synaptic transmission during repetitive nerve firing. Impaired endocytosis in pathological conditions leads to decreases in synaptic strength and brain functions. Here, we describe methods used to measure synaptic vesicle endocytosis at the mammalian hippocampal synapse in neuronal culture. We monitored synaptic vesicle protein endocytosis by fusing a synaptic vesicular membrane protein, including synaptophysin and VAMP2/synaptobrevin, at the vesicular lumenal side, with pHluorin, a pH-sensitive green fluorescent protein that increases its fluorescence intensity as the pH increases. During exocytosis, vesicular lumen pH increases, whereas during endocytosis vesicular lumen pH is re-acidified. Thus, an increase of pHluorin fluorescence intensity indicates fusion, whereas a decrease indicates endocytosis of the labelled synaptic vesicle protein. In addition to using the pHluorin imaging method to record endocytosis, we monitored vesicular membrane endocytosis by electron microscopy (EM) measurements of Horseradish peroxidase (HRP) uptake by vesicles. Finally, we monitored the formation of nerve terminal membrane pits at various times after high potassium-induced depolarization. The time course of HRP uptake and membrane pit formation indicates the time course of endocytosis.

Synaptic vesicle endocytosis is detected by light microscopy of pHluorin fused with synaptic vesicle protein and by electron microscopy of vesicle uptake.

During endocytosis, fused synaptic vesicles are retrieved at nerve terminals, allowing for vesicle recycling and thus the maintenance of synaptic ...

Pentylenetetrazole-Induced Kindling Mouse Model

Pentylenetetrazole (PTZ) is a GABA-A receptor antagonist. An intraperitoneal injection of PTZ into an animal induces an acute, severe seizure at a high dose, whereas sequential injections of a subconvulsive dose have been used for the development of chemical kindling, an epilepsy model. A single low-dose injection of PTZ induces a mild seizure without convulsion. However, repetitive low-dose injections of PTZ decrease the threshold to evoke a convulsive seizure. Finally, continuous low-dose administration of PTZ induces a severe tonic-clonic seizure. This method is simple and widely applicable to investigate the pathophysiology of epilepsy, which is defined as a chronic disease that involves repetitive seizures. This chemical kindling protocol causes repetitive seizures in animals. With this method, vulnerability to PTZ-mediated seizures or the degree of aggravation of epileptic seizures was estimated. These advantages have led to the use of this method for screening anti-epileptic drugs and epilepsy-related genes. In addition, this method has been used to investigate neuronal damage after epileptic seizures because the histological changes observed in the brains of epileptic patients also appear in the brains of chemical-kindled animals. Thus, this protocol is useful for conveniently producing animal models of epilepsy.

This protocol describes a method of chemical kindling with pentylenetetrazole and provides a mouse model of epilepsy. This protocol can also be used to investigate vulnerability to seizure induction and pathogenesis after epileptic seizures in mice.

Pentylenetetrazole (PTZ) is a GABA-A receptor antagonist. An intraperitoneal injection of PTZ into an animal induces an acute, severe seizure at a high ...

Preparation of Acute Spinal Cord Slices for Whole-cell Patch-clamp Recording in Substantia Gelatinosa Neurons

Recent whole-cell patch-clamp studies from substantia gelatinosa (SG) neurons have provided a large body of information about the spinal mechanisms underlying sensory transmission, nociceptive regulation, and chronic pain or itch development. Implementations of electrophysiological recordings together with morphological studies based on the utility of acute spinal cord slices have further improved our understanding of neuronal properties and the composition of local circuitry in SG. Here, we present a detailed and practical guide for the preparation of spinal cord slices and show representative whole-cell recording and morphological results. This protocol permits ideal neuronal preservation and can mimic in vivo conditions to a certain extent. In summary, the ability to obtain an in vitro preparation of spinal cord slices enables stable current- and voltage-clamp recordings and could thus facilitate detailed investigations into the intrinsic membrane properties, local circuitry and neuronal structure using diverse experimental approaches.

Here, we describe the essential steps for whole-cell patch-clamp recordings made from substantia gelatinosa (SG) neurons in the in vitro spinal cord slice. This method allows the intrinsic membrane properties, synaptic transmission and morphological characterization of SG neurons to be studied.

Recent whole-cell patch-clamp studies from substantia gelatinosa (SG) neurons have provided a large body of information about the spinal mechanisms ...

Investigating Long-term Synaptic Plasticity in Interlamellar Hippocampus CA1 by Electrophysiological Field Recording

The study of synaptic plasticity in the hippocampus has focused on the use of the CA3-CA1 lamellar network. Less attention has been given to the longitudinal interlamellar CA1-CA1 network. Recently however, an associational connection between CA1-CA1 pyramidal neurons has been shown. Therefore, there is the need to investigate whether the longitudinal interlamellar CA1-CA1 network of the hippocampus supports synaptic plasticity.
We designed a protocol to investigate the presence or absence of long-term synaptic plasticity in the interlamellar hippocampal CA1 network using electrophysiological field recordings both in vivo and in vitro. For in vivo extracellular field recordings, the recording and stimulation electrodes were placed in a septal-temporal axis of the dorsal hippocampus at a longitudinal angle, to evoke field excitatory postsynaptic potentials. For in vitro extracellular field recordings, hippocampal longitudinal slices were cut parallel to the septal-temporal plane. Recording and stimulation electrodes were placed in the stratum oriens (S.O) and the stratum radiatum (S.R) of the hippocampus along the longitudinal axis. This enabled us to investigate the directional and layer specificity of evoked excitatory postsynaptic potentials. Already established protocols were used to induce long-term potentiation (LTP) and long-term depression (LTD) both in vivo and in vitro. Our results demonstrated that the longitudinal interlamellar CA1 network supports N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) with no directional or layer specificity. The interlamellar network, however, in contrast to the transverse lamellar network, did not present with any significant long-term depression (LTD).

We used recording and stimulation electrodes in longitudinal hippocampal brain slices and longitudinally positioned recording and stimulation electrodes in the dorsal hippocampus in vivo to evoke extracellular postsynaptic potentials and demonstrate long-term synaptic plasticity along the longitudinal interlamellar CA1.