This work is supported by NIH grant NS065183 and start-up funds from the Rutgers Robert Wood Johnson Medical School.

1. Preparing Rat Astrocyte Culture for Conditioned Media and Astrocyte-neuron Cocultures.
<ol>
	<li>Prepare dissection buffer (BSS, see Table 1 for recipe) and store at 4 &#176;C until ready for use.</li>
	<li>Anesthetize neonatal rat pups (P0-P2) with isoflurane in a 500 ml beaker.</li>
	<li>When pups are immobile, spray with 70% ethanol and decapitate.</li>
	<li>Remove the brain.
	<ol>
		<li>Hold the head firmly with a pair of Dumont #5 forceps, and use fine scissors to make a midline incision through the skin and skull.</li>
		<li>Expose the brain by reflecting the skull to the sides, and remove the brain into a dish containing cold BSS.</li>
	</ol>
	</li>
	<li>Separate the cerebral hemispheres from the diencephalon and the brain stem under a dissecting scope. Carefully remove all meninges by stabilizing the tissue with one pair of forceps and gently pulling away the meninges with another pair of forceps.</li>
	<li>Collect all hemispheres in one 60 mm dish. Using small scissors, mince tissue as finely as possible. Then transfer the minced tissue to a 50 ml conical tube.</li>
	<li>Add 1.5 ml of 1% DNase I and 1.5 ml of 2.5% trypsin and 12 ml of BSS (total volume of 15ml) to brains. Incubate in a shaking water bath for 15 min at 37 &#176;C. To ensure good mixing, tube is swirled by hand every 5 min.</li>
	<li>Transfer supernatant through a 70 &#956;m cell strainer over a new 50 ml conical tube. Add 3 ml FBS to this supernatant.</li>
	<li>To the remaining pieces, add 13.5 ml of BSS and 1.5 ml 2.5% trypsin and incubate in the shaking waterbath for another 15 min.</li>
	<li>Transfer the remaining supernatant through the cell strainer and combine with the supernatant from Step 1.8.</li>
	<li>Centrifuge at 1,000 RPM for 5 min to pellet the cells.</li>
	<li>Resuspend pellets in 5 ml of glial media. Supernatant can be centrifuged again to pellet the remaining cells.</li>
	<li>Count cells using a hemocytometer.</li>
	<li>Plate cells at a density of 1 x 107 per 150 cm2 flask.</li>
	<li>Change media to fresh glial media the day after plating. Afterwards, feed cells twice a week with glial media.</li>
	<li>When cells have reached &#62;80% confluency (approximately 10 days after plating), freeze cells down in 90% horse serum and 10% DMSO and keep stocks in liquid nitrogen. Cells are frozen at 2 x 106 per vial. Approximately 5 vials can be frozen from each flask.</li>
	<li>About 10-14 days before setting up the hippocampal culture, glial cells are plated from the frozen stocks. We usually plate five 6-well plates, which is enough to support the growth of 90 coverslips of hippocampal neurons (three 15 mm round coverslips per well). We also plate an additional eight to ten 60 mm dishes of glial cells, which is used for conditioning N2.1 media for transfection. The day before neuronal culture, cells should be fed with NB27 media. The astrocytes should ideally be &#62;90% confluent at this point. We find that freezing greatly reduces the number of microglia in the astroglial cultures. Since increased neurotoxicity is observed when microglia is present in the astroglial cultures, we always use astroglial culture prepared from frozen stocks for coculture with neurons.</li>
</ol>
2. Neuronal Culture
<ol>
	<li>Clean glass coverslips by first rinsing in milliQ water 2x. They are then soaked in concentrated nitric acid for 24 hr, and rinsed with milliQ water for at least five times over a total of 2 hr. Coverslips are dried and sterilized by baking in an oven at 225 &#176;C for 6 hr.</li>
	<li>Transfer coverslips to 60 mm dishes after sterilization. Place four dots of sterile paraffin near the outer edge of each coverslip to keep neurons separate from glial cells during coculture.</li>
	<li>Coat coverslips with 1 mg/ml poly-L-lysine in 0.1 M borate buffer overnight in 37 &#176;C incubator.</li>
	<li>The next day, rinse coverslips twice in sterile milliQ water for at least 15 min each. They are then incubated overnight in plating media in 37 &#176;C incubator.</li>
	<li>Euthanize pregnant rat (E18) by isoflurane anesthesia followed by pneumothorax, and euthanize embryonic rats by decapitation. Remove brains and dissect out the cerebral hemispheres as described above.</li>
	<li>Dissect out the hippocampi from the cerebral hemisphere. Place all hippocampi into a 15 ml conical tube, and digest with 0.25% trypsin (0.5 ml 2.5% Trypsin, 4.5 ml BSS) at 37 &#8451; for 15 min.</li>
	<li>Digested hippocampi are rinsed in BSS 3x for 5 min each. They are then triturated with a glass Pasteur pipette, and the cell density is determined by using a hemocytometer. Neurons are then seeded at a density of 2 x 105 cells per 60 mm dish.</li>
	<li>About 2-4 hr after plating, transfer coverslips with attached neurons to the dishes containing astroglial cells, with neurons facing down towards the glia. At DIV3, add cytosine arabinoside to the cells at a final concentration of 5 &#956;M to stop glia proliferation.</li>
</ol>
3. Calcium Transfection
<ol>
	<li>Condition N2.1 media on glia the day before transfection.</li>
	<li>On the day of the transfection, take conditioned N2.1 media off of glia and transfer into a new dish. Transfer coverslips with neurons into the conditioned N2.1 media. Let equilibrate in incubator for 10-30 min.</li>
	<li>To one set of sterile tubes, combine 1-4 &#956;g of DNA, 12.5 &#956;l of 2 M CaCl2, and sterile H2O for a total volume of 100 &#956;l. To a second set of tubes, add 100 &#956;l of 2x HBS.</li>
	<li>Add &#8539; volume of 2x HBS (12.5 &#956;l) at a time to the tube containing the CaCl2/DNA mixture, vortexing for a few seconds each time. Allow the tubes to sit for 15 min.</li>
	<li>After 15 min incubation, add the transfection mixture dropwise to the cells. Incubate for 1-1.5 hr. A layer of sand-like precipitates should be visible under the microscope using a 10X objective.</li>
	<li>After incubation, rinse coverslips twice with warm HBS wash buffer.</li>
	<li>Return coverslips to original dishes with glia, add kynurenic acid to a final concentration of 0.5 mM.</li>
	<li>Transfected neurons can be imaged live or processed for immunocytochemistry as early as the next day. Neurons can survive up to three weeks after transfection.</li>
</ol>

<ol>
	<li>Karra, D., Dahm, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfection+techniques+for+neuronal+cells.">Transfection techniques for neuronal cells.</a> J. Neurosci. 30, 6171-6177 (2010).</li><li>Zeitelhofer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-efficiency+transfection+of+mammalian+neurons+via+nucleofection.">High-efficiency transfection of mammalian neurons via nucleofection.</a> Nat. Protoc. 2, 1692-1704 (2007).</li><li>Janas, J., Skowronski, J., Van Aelst, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lentiviral+delivery+of+RNAi+in+hippocampal+neurons.">Lentiviral delivery of RNAi in hippocampal neurons.</a> Method Enzymol. 406, 593-605 (2006).</li><li>Graham, F. L., vander Eb, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+technique+for+the+assay+of+infectivity+of+human+adenovirus+5+DNA.">A new technique for the assay of infectivity of human adenovirus 5 DNA.</a> Virology. 52, 456-467 (1973).</li><li>Craig, A. M., Banker, G. a. G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfecting+cultured+neurons.">Transfecting cultured neurons.</a> Culturing Nerve Cells. , (1998).</li><li>Alavian, K. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bcl-xL+regulates+metabolic+efficiency+of+neurons+through+interaction+with+the+mitochondrial+F1FO+ATP+synthase.">Bcl-xL regulates metabolic efficiency of neurons through interaction with the mitochondrial F1FO ATP synthase.</a> Nat. Cell Biol. 13, 1224-1233 (2011).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+synaptic+function+by+VAC14,+a+protein+that+regulates+the+phosphoinositides+PI(3,5)P(2)+and+PI(5)P.">Modulation of synaptic function by VAC14, a protein that regulates the phosphoinositides PI(3,5)P(2) and PI(5)P.</a> EMBO J. 31, 3442-3456 (2012).</li><li>Dudek, H., Ghosh, A., Greenberg, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+phosphate+transfection+of+DNA+into+neurons+in+primary+culture.">Calcium phosphate transfection of DNA into neurons in primary culture.</a> Curr. Protoc. Neurosci. Chapter 3, Unit 3 11 (2001).</li><li>Goslin, K. A. H., Banker, G., Banker, G. a. G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+Hippocampal+Neurons+in+Low-Density+Culture.">Rat Hippocampal Neurons in Low-Density Culture.</a> Culturing Nerve Cells. , (1998).</li><li>Kohrmann, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast,+convenient,+and+effective+method+to+transiently+transfect+primary+hippocampal+neurons.">Fast, convenient, and effective method to transiently transfect primary hippocampal neurons.</a> J. Neurosci. Res. 58, 831-835 (1999).</li><li>Jiang, M., Chen, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+Ca2+-phosphate+transfection+efficiency+in+low-density+neuronal+cultures.">High Ca2+-phosphate transfection efficiency in low-density neuronal cultures.</a> Nat. Protoc. 1, 695-700 (2006).</li><li>Goetze, B., Grunewald, B., Baldassa, S., Kiebler, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemically+controlled+formation+of+a+DNA/calcium+phosphate+coprecipitate:+application+for+transfection+of+mature+hippocampal+neurons.">Chemically controlled formation of a DNA/calcium phosphate coprecipitate: application for transfection of mature hippocampal neurons.</a> J. Neurobiol. 60, 517-525 (2004).</li></ol>

No conflicts of interested declared.

There are several key parameters that need to be carefully controlled for consistently successful transfections10,11. The most critical parameter for calcium phosphate transfection is the pH value of 2x&#160;HBS, which in our hands usually varies between 7.10-7.15. We recommend making three batches of stocks with pH values in 0.05 increments to account for the difference between pH meters. Alternatively, the Clontech mammalian transfection kit provides 2x HBS that consistently yields good efficiency. Keep in m...

Primary neurons are one of the hardest cell types to transfect as they are postmitotic and are very sensitive to micro-environmental changes. There are four commonly used types of methods for expression of exogenous genes and short-hairpin RNAs (shRNAs) in these cells1. Each has its own advantages and disadvantages. For example, electroporation is usually performed on freshly isolated neurons2, as cells must be transferred into cuvettes for transfection. Virus infection can usually achieve very high efficiency3, but is more labor-intensive and risky for operators. Many lipid-mediated transfection reagents are available commercially, with varying degrees of success in neurons and different levels of cytotoxicity.
Calcium phosphate transfection represents a convenient and economical method for introducing foreign genes into neurons. The method was first used to introduce adenovirus DNA into mammalian cells by Graham and Van Der Eb (1973)4. Transfection was performed by mixing calcium chloride with recombinant DNA in a phosphate buffer. This allows the formation of DNA/calcium phosphate precipitates which, when gradually dropped onto a monolayer of cells, adhere to the cell surface, are taken up by endocytosis and finally enter the nucleus5. This process would lead to the expression of introduced foreign genes in the target cell. Typical efficiencies of calcium phosphate transfection range between 0.5-5%6-8. However, with careful optimization and consistent execution of the experimental protocol, it is possible to reach a transfection efficiency of almost 50%. Here we describe our detailed protocol for calcium phosphate transfection of primary hippocampal neurons, which are cocultured with astroglial cells in a sandwich format9.

<table border="0" cellpadding="0" cellspacing="0" width="879">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="24">
			<td height="24" style="height:24px;width:284px;">Dumont #5 forceps</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">11251-20</td>
			<td style="width:269px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Fine scissors</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">14090-09</td>
			<td>straight / sharp 8.5 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Vannas-Tubinger spring scissors</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">15008-08</td>
			<td>angled / sharp / 8.5 cm / 5 mm cutting edge</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Standard pattern forceps</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">11000-16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Student surgical scissors</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">91401-14</td>
			<td>blunt / 14.5 cm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Spring scissors</td>
			<td style="width:207px;">Fine Science Tools</td>
			<td style="width:119px;">15006-09</td>
			<td>angled to side / 9 cm / 10 mm cutting edge</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Isoflurane</td>
			<td style="width:207px;">Webster Veterinary</td>
			<td style="width:119px;">14043-225-06</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Poly-L-lysine</td>
			<td>Sigma</td>
			<td style="width:119px;">P2636</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM</td>
			<td>Sigma</td>
			<td>M2279</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">100 mM Sodium pyruvate</td>
			<td style="width:207px;">Sigma</td>
			<td style="width:119px;">S8636</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Glucose</td>
			<td style="width:207px;">Sigma</td>
			<td style="width:119px;">G8270</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10x HBSS</td>
			<td>Sigma</td>
			<td>H4385</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">1 M HEPES, pH 7.3</td>
			<td>Gibco/Invitrogen</td>
			<td>15630-080</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GlutaMAX</td>
			<td>Gibco/Invitrogen</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Neurobasal Media</td>
			<td>Gibco/Invitrogen</td>
			<td>21130-049</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">B27 Supplement (50x)</td>
			<td>Gibco/Invitrogen</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">N2 Supplement</td>
			<td>Gibco/Invitrogen</td>
			<td>17502-048</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ovalbumin</td>
			<td style="width:207px;">Sigma</td>
			<td style="width:119px;">A5503</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin/Streptomycin</td>
			<td>Gibco/Invitrogen</td>
			<td style="width:119px;">15070-063</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">2.5% Trypsin</td>
			<td>Gibco/Invitrogen</td>
			<td style="width:119px;">15090-046</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">DNase I</td>
			<td style="width:207px;">Sigma</td>
			<td style="width:119px;">DN-25</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">Cytosine arabinoside</td>
			<td style="width:207px;">Calbiochem/EMD Millipore</td>
			<td align="right" style="width:119px;">251010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:284px;">Kynurenic acid</td>
			<td style="width:207px;">Sigma</td>
			<td style="width:119px;">K3375</td>
			<td></td>
		</tr>
	</tbody>
</table>

calcium phosphate transfection of primary hippocampal neurons

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this method on hard-to-transfect cells like primary neurons. Here we describe our detailed protocol for calcium phosphate transfection of hippocampal neurons cocultured with astroglial cells.

When the different parameters of transfection are optimized and carefully controlled from experiment to experiment, it is possible to obtain transfection efficiencies of up to 50%. Figure 1 shows a field of neurons that are transfected with GFP on DIV4. The field contains a total of 28 neurons, among which 16 were transfected. This represents an efficiency of over 50%. A sampling of other fields on the same coverslip shows the overall efficiency is around 50% (data not shown). With the astroglial cocultu...

Watch this Scientific Journal Video about Calcium Phosphate Transfection of Primary Hippocampal Neurons at JoVE.com

Calcium Phosphate Transfection of Primary Hippocampal Neurons

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this ...

calcium-phosphate-transfection-of-primary-hippocampal-neurons

Research

JoVE Journal

Neuroscience

25.1K Views.  Rutgers University.  Precipitazione di fosfato di calcio è un metodo conveniente ed economico per la trasfezione di cellule in coltura. Con ottimizzazione, è possibile usare questo metodo su cellule di difficile trasfezione come neuroni primari. Qui descriviamo il nostro protocollo dettagliato per fosfato di calcio trasfezione di neuroni dell'ippocampo co-coltivate con le cellule astrogliali. 

Video: Calcium Phosphate Transfection of Primary Hippocampal Neurons

Nucleofection and Primary Culture of Embryonic Mouse Hippocampal and Cortical Neurons

Hippocampal and cortical neurons have been used extensively to study central nervous system (CNS) neuronal polarization, axon/dendrite outgrowth, and synapse formation and function. An advantage of culturing these neurons is that they readily polarize, forming distinctive axons and dendrites, on a two dimensional substrate at very low densities. This property has made them extremely useful for determining many aspects of neuronal development. Furthermore, by providing glial conditioning for these neurons they will continue to develop, forming functional synaptic connections and surviving for several months in culture. In this protocol we outline a technique to dissect, culture and transfect embryonic mouse hippocampal and cortical neurons. Transfection is accomplished by electroporating DNA into the neurons before plating via nucleofection. This protocol has the advantage of expressing fluorescently-tagged fusion proteins early in development (~4-8hrs after plating) to study the dynamics and function of proteins during polarization, axon outgrowth and branching. We have also discovered that this single transfection before plating maintains fluorescently-tagged fusion protein expression at levels appropriate for imaging throughout the lifetime of the neuron (&gt; 2 months in culture). Thus, this methodology is useful for studying protein localization and function throughout CNS development with little or no disruption of neuronal function.

This protocol outlines the steps required to dissect, transfect via electroporation and culture mouse hippocampal and cortical neurons. Short-term cultures may be used for studies of axon outgrowth and guidance, while long-term cultures can be used for studies of synaptogenesis and dendritic spine analysis.

Hippocampal and cortical neurons have been used extensively to study central nervous system (CNS) neuronal polarization, axon/dendrite outgrowth, and ...

Isolation and Culture of Hippocampal Neurons from Prenatal Mice

Primary cultures of rat and murine hippocampal neurons are widely used to reveal cellular mechanisms in neurobiology. By isolating and growing individual neurons, researchers are able to analyze properties related to cellular trafficking, cellular structure and individual protein localization using a variety of biochemical techniques. Results from such experiments are critical for testing theories addressing the neural basis of memory and learning. However, unambiguous results from these forms of experiments are predicated on the ability to grow neuronal cultures with minimum contamination by other brain cell types. In this protocol, we use specific media designed for neuron growth and careful dissection of embryonic hippocampal tissue to optimize growth of healthy neurons while minimizing contaminating cell types (i.e. astrocytes). Embryonic mouse hippocampal tissue can be more difficult to isolate than similar rodent tissue due to the size of the sample for dissection. We show detailed dissection techniques of hippocampus from embryonic day 19 (E19) mouse pups. Once hippocampal tissue is isolated, gentle dissociation of neuronal cells is achieved with a dilute concentration of trypsin and mechanical disruption designed to separate cells from connective tissue while providing minimum damage to individual cells. A detailed description of how to prepare pipettes to be used in the disruption is included. Optimal plating densities are provided for immuno-fluorescence protocols to maximize successful cell culture. The protocol provides a fast (approximately 2 hr) and efficient technique for the culture of neuronal cells from mouse hippocampal tissue.

We provide a protocol for the culture of highly purified hippocampal neurons from prenatal mouse brains without the use of a feeder glial cell layer.

Primary cultures of rat and murine hippocampal neurons are widely used to reveal cellular mechanisms in neurobiology. By isolating and growing individual ...

Imaging Dendritic Spines of Rat Primary Hippocampal Neurons using Structured Illumination Microscopy

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. Technological advances have identified these structures as key elements in neuron connectivity and synaptic plasticity. The quantitative analysis of spine morphology using light microscopy remains an essential problem due to technical limitations associated with light's intrinsic refraction limit. Dendritic spines can be readily identified by confocal laser-scanning fluorescence microscopy. However, measuring subtle changes in the shape and size of spines is difficult because spine dimensions other than length are usually smaller than conventional optical resolution fixed by light microscopy's theoretical resolution limit of 200 nm.
Several recently developed super resolution techniques have been used to image cellular structures smaller than the 200 nm, including dendritic spines. These techniques are based on classical far-field operations and therefore allow the use of existing sample preparation methods and to image beyond the surface of a specimen. Described here is a working protocol to apply super resolution structured illumination microscopy (SIM) to the imaging of dendritic spines in primary hippocampal neuron cultures. Possible applications of SIM overlap with those of confocal microscopy. However, the two techniques present different applicability. SIM offers higher effective lateral resolution, while confocal microscopy, due to the usage of a physical pinhole, achieves resolution improvement at the expense of removal of out of focus light. In this protocol, primary neurons are cultured on glass coverslips using a standard protocol, transfected with DNA plasmids encoding fluorescent proteins and imaged using SIM. The whole protocol described herein takes approximately 2 weeks, because dendritic spines are imaged after 16-17 days in vitro, when dendritic development is optimal. After completion of the protocol, dendritic spines can be reconstructed in 3D from series of SIM image stacks using specialized software.

This article describes a working protocol to image dendritic spines from hippocampal neurons in vitro using Structured Illumination Microscopy (SIM). Super-resolution microscopy using SIM provides image resolution significantly beyond the light diffraction limit in all three spatial dimensions, allowing the imaging of individual dendritic spines with improved detail.

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. ...

Primary Culture of Mouse Dopaminergic Neurons

Dopaminergic neurons represent less than 1% of the total number of neurons in the brain. This low amount of neurons regulates important brain functions such as motor control, motivation, and working memory. Nigrostriatal dopaminergic neurons selectively degenerate in Parkinson&#39;s disease (PD). This progressive neuronal loss is unequivocally associated with the motors symptoms of the pathology (bradykinesia, resting tremor, and muscular rigidity). The main agent responsible of dopaminergic neuron degeneration is still unknown. However, these neurons appear to be extremely vulnerable in diverse conditions. Primary cultures constitute one of the most relevant models to investigate properties and characteristics of dopaminergic neurons. These cultures can be submitted to various stress agents that mimic PD pathology and to neuroprotective compounds in order to stop or slow down neuronal degeneration. The numerous transgenic mouse models of PD that have been generated during the last decade further increased the interest of researchers for dopaminergic neuron cultures. Here, the video protocol focuses on the delicate dissection of embryonic mouse brains. Precise excision of ventral mesencephalon is crucial to obtain neuronal cultures sufficiently rich in dopaminergic cells to allow subsequent studies. This protocol can be realized with embryonic transgenic mice and is suitable for immunofluorescence staining, quantitative PCR, second messenger quantification, or neuronal death/survival assessment.

Dopaminergic neurons play a vital regulatory role in the brain. Their loss is associated with Parkinson's disease. In this video, we show how to generate primary cultures of central dopaminergic neurons from embryonic mouse mesencephalon. Such cultures are useful to study the extreme vulnerability of these neurons to various stresses.

Dopaminergic neurons represent less than 1% of the total number of neurons in the brain. This low amount of neurons regulates important brain functions ...

Fluorescence and Bioluminescence Imaging of Subcellular Ca2+ in Aged Hippocampal Neurons

Susceptibility to neuron cell death associated to neurodegeneration and ischemia are exceedingly increased in the aged brain but mechanisms responsible are badly known. Excitotoxicity, a process believed to contribute to neuron damage induced by both insults, is mediated by activation of glutamate receptors that promotes Ca2+ influx and mitochondrial Ca2+ overload. A substantial change in intracellular Ca2+ homeostasis or remodeling of intracellular Ca2+ homeostasis may favor neuron damage in old neurons. For investigating Ca2+ remodeling in aging we have used live cell imaging in long-term cultures of rat hippocampal neurons that resemble in some aspects aged neurons in vivo. For this end, hippocampal cells are, in first place, freshly dispersed from new born rat hippocampi and plated on poli-D-lysine coated, glass coverslips. Then cultures are kept in controlled media for several days or several weeks for investigating young and old neurons, respectively. Second, cultured neurons are loaded with fura2 and subjected to measurements of cytosolic Ca2+ concentration using digital fluorescence ratio imaging. Third, cultured neurons are transfected with plasmids expressing a tandem of low-affinity aequorin and GFP targeted to mitochondria. After 24 hr, aequorin inside cells is reconstituted with coelenterazine and neurons are subjected to bioluminescence imaging for monitoring of mitochondrial Ca2+ concentration. This three-step procedure allows the monitoring of cytosolic and mitochondrial Ca2+ responses to relevant stimuli as for example the glutamate receptor agonist NMDA and compare whether these and other responses are influenced by aging. This procedure may yield new insights as to how aging influence cytosolic and mitochondrial Ca2+ responses to selected stimuli as well as the testing of selected drugs aimed at preventing neuron cell death in age-related diseases.

Fluorescence and Bioluminescence Imaging of Subcellular Ca2+ in Aged Hippocampal Neurons

Intracellular Ca2+ remodeling in aging may contribute to excitotoxicity and neuron damage, processes mediated by Ca2+ overload. We aimed at investigating Ca2+ remodeling in the aging brain using fluorescence and bioluminescence imaging of cytosolic and mitochondrial Ca2+ in long-term cultures of rat hippocampal neurons, a model of neuronal aging.

Susceptibility to neuron cell death associated to neurodegeneration and ischemia are exceedingly increased in the aged brain but mechanisms responsible ...

Low-Density Primary Hippocampal Neuron Culture

The ability to probe the structure and physiology of individual nerve cells in culture is crucial to the study of neurobiology, and allows for flexibility in genetic and chemical manipulation of individual cells or defined networks. Such ease of manipulation is simpler in the reduced culture system when compared to the intact brain tissue. While many methods for the isolation and growth of these primary neurons exist, each has its own limitations. This protocol describes a method for culturing low-density and high-purity rodent embryonic hippocampal neurons on glass coverslips, which are then suspended over a monolayer of glial cells. This &#39;sandwich culture&#39; allows for exclusive long-term growth of a population of neurons while allowing for trophic support from the underlying glial monolayer. When neurons are of sufficient age or maturity level, the neuron coverslips can be flipped-out of the glial dish and used in imaging or functional assays. Neurons grown by this method typically survive for several weeks and develop extensive arbors, synaptic connections, and network properties.

This article describes the protocol for culturing low-density primary hippocampal neurons growing on glass coverslips inverted over a glial monolayer. The neuron and glial layers are separated by paraffin wax beads. The neurons grown by this method are suitable for high-resolution optical imaging and functional assays.

The ability to probe the structure and physiology of individual nerve cells in culture is crucial to the study of neurobiology, and allows for flexibility ...

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 ...

Generation of Neurospheres from Mixed Primary Hippocampal and Cortical Neurons Isolated from E14-E16 Sprague Dawley Rat Embryo

Primary neuron culture is an essential technique in the field of neuroscience. To gain deeper mechanistic insights into the brain, it is essential to have a robust in vitro model that can be exploited for various neurobiology studies. Though primary neuron cultures (i.e., long-term hippocampal cultures) have provided scientists with models, it does not yet represent the complexity of brain network completely. In the wake of these limitations, a new model has emerged using neurospheres, which bears a closer resemblance to the brain tissue. The present protocol describes the plating of high and low densities of mixed cortical and hippocampal neurons isolated from the embryo of embryonic day 14-16 Sprague Dawley rats. This allows for the generation of neurospheres and long-term primary neuron culture as two independent platforms to conduct further studies. This process is extremely simple and cost-effective, as it minimizes several steps and reagents previously deemed essential for neuron culture. This is a robust protocol with minimal requirements that can be performed with achievable results and further used for a diversity of studies related to neuroscience.

Presented here is a protocol for the spontaneous generation of neurospheres enriched in neural progenitor cells from high density plated neurons. During the same experiment, when neurons are plated at a lower density, the protocol also results in prolonged primary rat neuron cultures.

Primary neuron culture is an essential technique in the field of neuroscience. To gain deeper mechanistic insights into the brain, it is essential to have ...

Use of Primary Cultured Hippocampal Neurons to Study the Assembly of Axon Initial Segments

Neuronal axon initial segments (AIS) are sites of initiation of action potentials and have been extensively studied for their molecular structure, assembly and activity-dependent plasticity. Giant ankyrin-G, the master organizer of AIS, directly associates with membrane-spanning voltage gated sodium (VSVG) and potassium channels (KCNQ2/3), as well as 186 kDa neurofascin, a L1CAM cell adhesion molecule. Giant ankyrin-G also binds to and recruits cytoplasmic AIS molecules including beta-4-spectrin, and the microtubule-binding proteins, EB1/EB3 and Ndel1. Giant ankyrin-G is sufficient to rescue AIS formation in ankyrin-G deficient neurons. Ankyrin-G also includes a smaller 190 kDa isoform located at dendritic spines instead of the AIS, which is incapable of targeting to the AIS or rescuing the AIS in ankyrin-G-deficient neurons. Here, we described a protocol using cultured hippocampal neurons from ANK3-E22/23-flox mice, which, when transfected with Cre-BFP exhibit loss of all isoform of ankyrin-G and impair the formation of AIS. Combined a modified Banker glia/neuron co-culture system, we developed a method to transfect ankyrin-G null neurons with a 480 kDa ankyrin-G-GFP plasmid, which is sufficient to rescue the formation of AIS. We further employ a quantification method, developed by Salzer and colleagues to deal with variation in AIS distance from the neuronal cell bodies that occurs in hippocampal neuron cultures. This protocol allows quantitative studies of the de novo assembly and dynamic behavior of AIS.

Here, we described a protocol to quantitatively study the assembly and structure of the axon initial segments (AIS) of hippocampal neurons that lack pre-assembled AIS due to the absence of a giant ankyrin-G.

Neuronal axon initial segments (AIS) are sites of initiation of action potentials and have been extensively studied for their molecular structure, ...

Easy and Reproducible Low-Density Primary Culture using Frozen Stock of Embryonic Hippocampal Neurons

Neuronal culture is a valuable system for evaluating synaptic functions and drug screenings. In particular, a low-density culture of primary hippocampal neurons allows the study of individual neurons or subcellular components. We have shown subcellular protein localization within a neuron by immunocytochemistry, neuronal polarity, synaptic morphology, and its developmental change using a low-density primary hippocampal culture. Recently, ready-to-use frozen stocks of neurons have become commercially available. These frozen stocks of neurons reduce the time needed to prepare animal experiments and also contribute to the reduction of the number of animals used. Here, we introduce a reproducible low-density primary culture method using a 96-well plate. We used a commercially available frozen stock of neurons from the rat embryonic hippocampus. The neurons can be stably cultured long-term without media changes by reducing the growth of glial cells at particular timepoints. This high-throughput assay using low-density culture allows reproducible imaging-based evaluations of synaptic plasticity.

A ready-to-use frozen stock of neurons is a powerful tool for evaluating synaptic functions. Here, we introduce an easy low-density primary culture from frozen stock using a 96-well plate.

Neuronal culture is a valuable system for evaluating synaptic functions and drug screenings. In particular, a low-density culture of primary hippocampal ...