This study was supported by FMMU new finding foundation and partially NIH funding.

1. Glia Cell Culture
Glial cells can be cultured from different regions of central nervous system. The whole process is shown in process figure.
<img src="/files/ftp_upload/2111/2111process.jpg" alt="Process 1" />
Day 1 Coating culture plate and coverslips
<ol>
	<li>Dry sterilized glass microscope round coverslips in an autoclave.</li>
	<li>Plate the sterilized coverslips into sterilized 24-well culture plate.</li>
	<li>Coat the coverslips with poly-lysine and incubate for 2 hours under root temperature.</li>
	<li>Coat 6-well culture plates in the same way as step 3.</li>
	<li>Wash the coverslips and 6-well culture plate twice with distilled water and air dry in culture hood.</li>
	<li>Add 200 &mu;L DMEM medium(with 10% FBS) in each well in 24-well plate and 2 mL in each well in 6-well plate and put them into incubator under 37 degree with 5% CO2</li>
</ol>
Day 2 Isolating cortex and glial cell culture
<ol>
	<li>Sterilize the positive flow dissection hood.</li>
	<li>Turn on UV light for 20 min.</li>
	<li>Spray all surfaces with 70% ethanol and wait 15 min before use.</li>
	<li>change tense: Anesthetize rat pups (P2-P6) by hypothermia, and decapitate at the base of the framen magnum using operating scissors.</li>
	<li>Open the cranium along the sagittal suture using an iris scissor and peel off the skull.</li>
	<li>Remove the forebrain and put them into chilled L15 medium, under stereomicroscope, carefully clean the dura and pia membrane with blood vessels, isolate the cortex and wash several times with L15 medium.</li>
	<li>Cut the cortex into small pieces with microsurgery scissor.</li>
	<li>Add 0.125% trypsin-EDTA prepared with L15 medium into cortex pieces and incubate in 37 degree for 15 min.</li>
	<li>Transfer tissue blocks into 20mL DMEM medium with 20% FBS in 50mL tube, add DNase stock solution to final concentration 10ug/mL, aspirate the tissue solution up and down for 20 times with fire polished glass Pasteure pipette, collect the single cells suspension.</li>
	<li>Wash the cell suspension one time with DMEM medium, re-suspend cells in DMEM with 10% FBS, count cells under microscope with a hemocytometer, seed cells at 5000-10000/cm2. Maintain cells in a 37 degree 5% incubator, change half of the medium 2 times per week.</li>
</ol>
2. Dorsal Root Ganglia Neurons Isolation, Culture and Purification
Day 1 Prepare Culture Material
<ol>
	<li>Coat the sterilized coverslips with poly-lysine, wash coverslips twice with distill water and air dry, put them into 24-well plates.</li>
	<li>Add 100&mu;L Neurobasal medium with 2% B27 and 2.5S NGF (50 ng/mL), put plate into 37 degree 5% CO2.</li>
</ol>
Day 2 Isolate DRGs from embryos
<ol>
	<li>Sterilized the flow hood in the same way as glial cell culture.</li>
	<li>Euthanize a pregnant rat (E15) by overdose with CO2, sterilized abdomen by 70% ethanol, embryos were isolated from uterus and put into chilled L15 medium.</li>
	<li>Isolate Spinal cords with connected dorsal root ganglia under stereomicroscope and transfer to 35mm dishes with chilled L15 medium. </li>
	<li>Collect single cell suspension and wash once with NBF medium (Neurobasal medium containing 2% B27 and 2.5S NGF (50 ng/mL)).</li>
</ol>
Day 3 Purify DRG Neurons
<ol>
	<li>18h-24h after neuron seeding, add a 1 mM concentrated FUDR stock solution to the neuron culture to a final concentration of 20 &mu;M and a final volume of 200 &mu;L.</li>
	<li>72h later, replace half the medium with Neurobasal medium containing 2% B27 and 2.5S NGF (50ng/mL) without FUDR. After that, change the medium every other day.</li>
</ol>
3. Coculture DRG neurons with glial cells
<ol>
 <li>When glial cell culture reached confluence (around 20 days after seeding), they were ready for coculture with neurons.</li>
	<li>24 hours before adding the purified neurons, glial cells medium were changed to Neurobasal medium containing 2% B27 and 2.5S NGF(50 ng/mL).</li>
	<li>Purified neurons were collected from culture wells, single cells suspension were obtained by mechanical passing through fire polished Pasteure pipette.</li>
	<li>After counting the number, neurons were seeded at 500/cm2 on confluent glial cells in Neurobasal medium containing 2% B27 and 2.5S NGF (50ng/mL).</li>
	<li>Neurons adhesion and neurite growth on glial cells could be recorded and analyzed at different time points by image analysis software and immunocytochemistry using cell type specific antibodies.</li>
</ol>
4. Representative Results
<ol>
	<li>Glial cell culture: After seeding, glial cells will become confluent around 20 days. Under phase contrast microscope, it was easily identified that different morphological glial cell subpopulations formed different growth pattern substructures and the GFAP positive astrocytes accounted for more than 90% as shown by immuocytochemisty technique (Figure 1, Figure 2).</li>
	<li>DRG neurons culture: In our method, after 72 hours FUDR treatment, the purity of DRG neurons will reach as high as 99% within 6 days, DRG neurons showed their unique morphologies and with high density neurite growth(Figure 3, Figure 4).</li>
	<li>Glial cell and neurons coculture: DRG neurons adhesion and neurite outgrowth occurred readily on glial cells within 4 hours after seeding, careful observations showed that neuron adhesion and neurite growth were influenced by glial cell subpopulations which formed special growth pattern substructures, this could be easily identified under phase contrast microscope and by immunocytochemistry(Figure 5, Figure 6).</li>
</ol>
<img src="/files/ftp_upload/2111/2111fig1.jpg" alt="Figure 1" /> Figure 1. Morphology of confluent glial cells. Cortical glial cells were plated on polylysine coated coverslip and cultured for 20 days, note the different growth pattern of glial cells, cells on the left side arranged in a radiated way.
<img src="/files/ftp_upload/2111/2111fig2.jpg" alt="Figure 2" /> Figure 2. Confluent glial cells labeled by Glial fibrillary acidic protein (GFAP) antibody. Note the radiated arrangement of GFAP (red) positive cells on the right side.
<img src="/files/ftp_upload/2111/2111fig3.jpg" alt="Figure 3" /> Figure 3. Dorsal root ganglia neurons grew in vitro without FUDR treatment. The contaminating cells formed DRG neurons' background.
<img src="/files/ftp_upload/2111/2111fig4.jpg" alt="Figure 4" /> Figure 4. Dorsal root ganglia neurons grew in vitro after FUDR treatment. The background contaminating cells had been eliminated completely.
<img src="/files/ftp_upload/2111/2111fig5.jpg" alt="Figure 5" /> Figure 5. Dorsal root ganglia neurons grown on glial cells. Neurons adhesion and neurite growth were inhibited on the radiated arranged cells and limited on the right side glial cells.
<img src="/files/ftp_upload/2111/2111fig6.jpg" alt="Figure 6" /> Figure 6. Dorsal root ganglia neurons growing on glial cells labeled by neurofilament antibody. The neurite(green) were inhibited on the radiated arranged left side glial cells and limited on the right side, all the glial cells were labeled by GFAP antibody(red).

<ol>
	<li>Rossignol, S., Schwab, M., Schwartz, M., Fehlings, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+cord+injury:+time+to+move?.">Spinal cord injury: time to move?.</a> J Neurosci. 27 (44), 11782-11792 (2007).</li><li>Yiu, G., He, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+inhibition+of+CNS+axon+regeneration.">Glial inhibition of CNS axon regeneration.</a> Nat Rev Neurosci. 7 (8), 617-627 (2006).</li><li>Barres, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mystery+and+magic+of+glia:+a+perspective+on+their+roles+in+health+and+disease.">The mystery and magic of glia: a perspective on their roles in health and disease.</a> Neuron. 60 (3), 430-440 (2008).</li><li>Matyash, V., Kettenmann, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterogeneity+in+astrocyte+morphology+and+physiology.">Heterogeneity in astrocyte morphology and physiology.</a> Brain Res Rev. , (2009).</li><li>Wanner, I. B., Deik, A., Torres, M., Rosendahl, A., Neary, J. T., Lemmon, V. P., Bixby, J. L. <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+in+vitro+model+of+the+glial+scar+inhibits+axon+growth.+Glia.">A new in vitro model of the glial scar inhibits axon growth. Glia.</a> 56 (15), 1691-1709 (2008).</li><li>Kuffler, D. P., Sosa, I. J., Reyes, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schwann+cell+chondroitin+sulfate+proteoglycan+inhibits+dorsal+root+ganglion+neuron+neurite+outgrowth+and+substrate+specificity+via+a+soma+and+not+a+growth+cone+mechanism.">Schwann cell chondroitin sulfate proteoglycan inhibits dorsal root ganglion neuron neurite outgrowth and substrate specificity via a soma and not a growth cone mechanism.</a> J Neurosci Res. 87 (13), 2863-2871 (2009).</li><li>Kleitman, N., Wood, P. M., Bunge, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+culture+method+for+the+study+of+myelination.">Tissue culture method for the study of myelination.</a> Culturing nerve cells. , P559-P559 (1998).</li></ol>

No conflicts of interest declared.

This experiment protocol was designed to reach two goals to study glial cells, especially astrocyte heterogeneity's influence on neuron adhesion and neurite growth. The first goal was to maintain astrocyte heterogeneity as much as possible, in this experiment, the confluent glial cell culture enriched astrocytes was mixed primary culture without any chemical treatment and digestion propagation, which may further damage the cell and induce injury response of astrocytes. The final astrocyte purity is more than 90% GFAP pos...

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>DMEM(high glucose)</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>10313-039</td>
<td>&nbsp;</td>
<tr>
<td>L15 medium</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>11415-114</td>
<td>&nbsp;</td>
<tr>
<td>FBS</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>10437-077</td>
<td>&nbsp;</td>
<tr>
<td>Neurobasal Medium</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>21103-049</td>
<td>&nbsp;</td>
<tr>
<td>poly-lysine</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>P4832</td>
<td>culture grade</td>
</tr>
<tr>
<td>NGF(2.5S)</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>13257-019</td>
<td>&nbsp;</td>
<tr>
<td>B27 supplyment</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>17504-044</td>
<td>&nbsp;</td>
<tr>
<td>0.25% trypsin-EDTA</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>25200-056</td>
<td>&nbsp;</td>
<tr>
<td>FUDR</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>F0503</td>
<td>&nbsp;</td>
<tr>
<td>neurofilament antibody</td>
<td>&nbsp;</td>
<td>Abcam</td>
<td>ab24575</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

study glial cell heterogeneity influence on axon growth using a new coculture method

In the central nervous system of all mammals, severed axons after injury are unable to regenerate to their original targets and functional recovery is very poor 1. The failure of axon regeneration is a combined result of several factors including the hostile glial cell environment, inhibitory myelin related molecules and decreased intrinsic neuron regenerative capacity 2. Astrocytes are the most predominant glial cell type in central nervous system and play important role in axon functions under physiology and pathology conditions 3. Contrast to the homologous oligodendrocytes, astrocytes are a heterogeneous cell population composed by different astrocyte subpopulations with diverse morphologies and gene expression 4. The functional significance of this heterogeneity, such as their influences on axon growth, is largely unknown.
To study the glial cell, especially the function of astrocyte heterogeneity in neuron behavior, we established a new method by co-culturing high purified dorsal root ganglia neurons with glial cells obtained from the rat cortex. By this technique, we were able to directly compare neuron adhesion and axon growth on different astrocytes subpopulations under the same condition.
In this report, we give the detailed protocol of this method for astrocytes isolation and culture, dorsal root ganglia neurons isolation and purification, and the co-culture of DRG neurons with astrocytes. This method could also be extended to other brain regions to study cellular or regional specific interaction between neurons and glial cells.

Watch this Scientific Journal Video about Study Glial Cell Heterogeneity Influence on Axon Growth Using a New Coculture Method at JoVE.com

Study Glial Cell Heterogeneity Influence on Axon Growth Using a New Coculture Method

In this protocol, we described a new method to study the influence of glial cell heterogeneity on axon growth with an in vitro co-culture system. Rat cortical glial cells were cultured to confluence and cocultured with highly purified rat dorsal root ganglia neurons. Different glial cell influence on neurons adhesion and axon growth was compared directly in the same culture. This method provides a new way to directly study the glial cell heterogeneity influence on neuron adhesion and axon growth.

In the central nervous system of all mammals, severed axons after injury are unable to regenerate to their original targets and functional recovery is ...

study-glial-cell-heterogeneity-influence-on-axon-growth-using-new

Research

JoVE Journal

Neuroscience

17.2K Aufrufe.  Cedars Sinai Medical Center, UCLA. In diesem Protokoll beschrieben wir eine neue Methode, um den Einfluss von Gliazellen Heterogenität auf Axon Wachstum mit einer Studie In-vitro- Co-Kultur-System. Rat kortikalen Gliazellen wurden bis zur Konfluenz kultiviert und kokultiviert mit hoch gereinigtem Ratten Spinalganglien Neuronen. Verschiedene Gliazellen Einfluss auf Neuronen Haftung und Axon-Wachstum wurde direkt in der gleichen Kultur verglichen. Diese Methode bietet eine neue Möglichkeit, ...

Serie: Study Glial Cell Heterogeneity Influence on Axon Growth Using a New Coculture Method

Genetic Study of Axon Regeneration with Cultured Adult Dorsal Root Ganglion Neurons

It is well known that mature neurons in the central nervous system (CNS) cannot regenerate their axons after injuries due to diminished intrinsic ability to support axon growth and a hostile environment in the mature CNS1,2. In contrast, mature neurons in the peripheral nervous system (PNS) regenerate readily after injuries3. Adult dorsal root ganglion (DRG) neurons are well known to regenerate robustly after peripheral nerve injuries. Each DRG neuron grows one axon from the cell soma, which branches into two axonal branches: a peripheral branch innervating peripheral targets and a central branch extending into the spinal cord. Injury of the DRG peripheral axons results in substantial axon regeneration, whereas central axons in the spinal cord regenerate poorly after the injury. However, if the peripheral axonal injury occurs prior to the spinal cord injury (a process called the conditioning lesion), regeneration of central axons is greatly improved4. Moreover, the central axons of DRG neurons share the same hostile environment as descending corticospinal axons in the spinal cord. Together, it is hypothesized that the molecular mechanisms controlling axon regeneration of adult DRG neurons can be harnessed to enhance CNS axon regeneration. As a result, adult DRG neurons are now widely used as a model system to study regenerative axon growth5-7.
Here we describe a method of adult DRG neuron culture that can be used for genetic study of axon regeneration in vitro. In this model adult DRG neurons are genetically manipulated via electroporation-mediated gene transfection6,8. By transfecting neurons with DNA plasmid or si/shRNA, this approach enables both gain- and loss-of-function experiments to investigate the role of any gene-of-interest in axon growth from adult DRG neurons. When neurons are transfected with si/shRNA, the targeted endogenous protein is usually depleted after 3-4 days in culture, during which time robust axon growth has already occurred, making the loss-of-function studies less effective. To solve this problem, the method described here includes a re-suspension and re-plating step after transfection, which allows axons to re-grow from neurons in the absence of the targeted protein. Finally, we provide an example of using this in vitro model to study the role of an axon regeneration-associated gene, c-Jun, in mediating axon growth from adult DRG neurons9.

An in vitro model for genetic study of axon regeneration using cultured adult mouse dorsal root ganglion neurons is described. The method includes a re-suspension/re-plating step to allow axon re-growth from neurons undergoing genetic manipulation. This approach is especially useful for loss-of-function studies of axon regeneration using RNAi-based protein knockdown.

It is well known that mature neurons in the central nervous system (CNS) cannot regenerate their axons after injuries due to diminished intrinsic ability ...

A Caenorhabditis elegans Model System for Amylopathy Study

Amylopathy is a term that describes abnormal synthesis and accumulation of amyloid beta (A&beta;) in tissues with time. A&beta; is a hallmark of Alzheimer's disease (AD) and is found in Lewy body dementia, inclusion body myositis and cerebral amyloid angiopathy 1-4. Amylopathies progressively develop with time. For this reason simple organisms with short lifespans may help to elucidate molecular aspects of these conditions. Here, we describe experimental protocols to study A&beta;-mediated neurodegeneration using the worm Caenorhabditis elegans. Thus, we construct transgenic worms by injecting DNA encoding human A&beta;42 into the syncytial gonads of adult hermaphrodites. Transformant lines are stabilized by a mutagenesis-induced integration. Nematodes are age synchronized by collecting and seeding their eggs. The function of neurons expressing A&beta;42 is tested in opportune behavioral assays (chemotaxis assays). Primary neuronal cultures obtained from embryos are used to complement behavioral data and to test the neuroprotective effects of anti-apoptotic compounds.

A Caenorhabditis elegans Model System for Amylopathy Study

We describe methods to study aspects of amylopathies in the worm C. elegans. We show how to construct worms expressing human A&beta;42 in neurons and how to test their function in behavioral assays. We further show how to obtain primary neuronal cultures that can be used for pharmacological testing.

Amylopathy is a term that describes abnormal synthesis and accumulation of amyloid beta (A&beta;) in tissues with time. A&beta; is a hallmark of ...

A Method to Make a Craniotomy on the Ventral Skull of Neonate Rodents

The use of a craniotomy for in vivo experiments provides an opportunity to investigate the dynamics of diverse cellular processes in the mammalian brain in adulthood and during development. Although most in vivo approaches use a craniotomy to study brain regions located on the dorsal side, brainstem regions such as the pons, located on the ventral side remain relatively understudied. The main goal of this protocol is to facilitate access to ventral brainstem structures so that they can be studied in vivo using electrophysiological and imaging methods. This approach allows study of structural changes in long-range axons, patterns of electrical activity in single and ensembles of cells, and changes in blood brain barrier permeability in neonate animals. Although this protocol has been used mostly to study the auditory brainstem in neonate rats, it can easily be adapted for studies in other rodent species such as neonate mice, adult rodents and other brainstem regions.

A surgical method is described to expose the ventral skull in neonate rats. Using this approach it is possible to open a craniotomy to perform acute electrophysiology and two-photon microscopy experiments in the brainstem of anesthetized pups.

The use of a craniotomy for in vivo experiments provides an opportunity to investigate the dynamics of diverse cellular processes in the mammalian brain ...

Inducing Plasticity of Astrocytic Receptors by Manipulation of Neuronal Firing Rates

Close to two decades of research has established that astrocytes in situ and in vivo express numerous G protein-coupled receptors (GPCRs) that can be stimulated by neuronally-released transmitter. However, the ability of astrocytic receptors to exhibit plasticity in response to changes in neuronal activity has received little attention. Here we describe a model system that can be used to globally scale up or down astrocytic group I metabotropic glutamate receptors (mGluRs) in acute brain slices. Included are methods on how to prepare parasagittal hippocampal slices, construct chambers suitable for long-term slice incubation, bidirectionally manipulate neuronal action potential frequency, load astrocytes and astrocyte processes with fluorescent Ca2+ indicator, and measure changes in astrocytic Gq GPCR activity by recording spontaneous and evoked astrocyte Ca2+ events using confocal microscopy. In essence, a &#8220;calcium roadmap&#8221; is provided for how to measure plasticity of astrocytic Gq GPCRs. Applications of the technique for study of astrocytes are discussed. Having an understanding of how astrocytic receptor signaling is affected by changes in neuronal activity has important implications for both normal synaptic function as well as processes underlying neurological disorders and neurodegenerative disease.

Here we describe an adaptation of protocols used to induce homeostatic plasticity in neurons for the study of plasticity of astrocytic G protein-coupled receptors. Recently used to examine changes in astrocytic group I mGluRs in juvenile mice, the method can be applied to measure scaling of various astrocytic GPCRs, in tissue from adult mice in situ and in vivo, and to gain a better appreciation of the sensitivity of astrocytic receptors to changes in neuronal activity.

Close to two decades of research has established that astrocytes in situ and in vivo express numerous G protein-coupled receptors (GPCRs) that can be ...

Preparation of Primary Mixed Glial Cultures from Adult Mouse Spinal Cord Tissue

It has been well-accepted that spinal cord glial responses contribute significantly to the development of neuropathic pain. Tremendous information regarding glial activities at the cellular and molecular levels has been obtained through in vitro cell culture systems. The in vitro systems utilized, mainly include primary glia derived from neonatal brain cortical tissue and immortalized cell lines. However, these systems may not reflect the characteristics of spinal cord glial cells in vivo. In order to further investigate the roles of spinal cord glial cells in the development of peripheral nerve injury-induced neuropathic pain using a culture system that better reflects the in vivo condition, our laboratory has developed a method to establish primary spinal cord mixed glial cultures from adult mice. Briefly, spinal cords are collected from adult mice and processed through papain digestion followed by myelin removal with a density-gradient medium. Single cell suspensions are cultured in complete Dulbecco&#39;s modified Eagle media (cDMEM) supplemented with 2-mercaptoethanol (2-ME) at 35.9 oC. These culture conditions were optimized specifically for the growth of mixed glial cells. Under these conditions, cells are ready to be used for experimentation between 12 - 14 d&#160;(cells are usually in log phase during this time) after the establishment of the culture (D 0) and can be kept in culture conditions up to D 21. This culture system can be used to investigate the responses of spinal cord glial cells upon stimulation with various substances and agents. Besides neuropathic pain, this system can be used to study glial responses in other diseases that involve pathological changes of spinal cord glial cells.

The development of neuropathic pain involves pathological changes of spinal cord glial cells. A reliable glial culture system derived from adult spinal cord tissue and designed for studying these cells in vitro is lacking. Therefore, we show here how&#160;to establish primary mixed glial cultures from adult mouse spinal cord tissue.

It has been well-accepted that spinal cord glial responses contribute significantly to the development of neuropathic pain. Tremendous information ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

Time-dependent Increase in the Network Response to the Stimulation of Neuronal Cell Cultures on Micro-electrode Arrays

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network dynamics in neuronal cultures. In contrast with more traditional methods, such as patch-clamping, which can only record activity from a single cell, MEAs can record simultaneously from multiple sites in a network, without requiring the arduous task of placing each electrode individually. Moreover, numerous control and stimulation configurations can be easily applied within the same experimental setup, allowing for a broad range of dynamics to be explored. One of the key dynamics of interest in these in vitro studies has been the extent to which cultured networks display properties indicative of learning. Mouse neuronal cells cultured on MEAs display an increase in response following training induced by electrical stimulation. This protocol demonstrates how to culture neuronal cells on MEAs; successfully record from over 95% of the plated dishes; establish a protocol to train the networks to respond to patterns of stimulation; and sort, plot, and interpret the results from such experiments. The use of a proprietary system for stimulating and recording neuronal cultures is demonstrated. Software packages are also used to sort neuronal units. A custom-designed graphical user interface is used to visualize post-stimulus time histograms, inter-burst intervals, and burst duration, as well as to compare the cellular response to stimulation before and after a training protocol. Finally, representative results and future directions of this research effort are discussed.

Mouse neuronal cells cultured on multi-electrode arrays display an increase in response following electrical stimulation. This protocol demonstrates how to culture neurons, how to record activity, and how to establish a protocol to train the networks to respond to patterns of stimulation.

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network ...

New Methods to Study Gustatory Coding

The sense of taste allows animals to detect chemicals in the environment, giving rise to behaviors critical for survival. When Gustatory Receptor Neurons (GRNs) detect tastant molecules, they encode information about the identity and concentration of the tastant as patterns of electrical activity that then propagate to follower neurons in the brain. These patterns constitute internal representations of the tastant, which then allow the animal to select actions and form memories. The use of relatively simple animal models has been a powerful tool to study basic principles in sensory coding. Here, we propose three new methods to study gustatory coding using the moth Manduca sexta. First, we present a dissection procedure for exposing the maxillary nerves and the subesophageal zone (SEZ), allowing recording of the activity of GRNs from their axons. Second, we describe the use of extracellular electrodes to record the activity of multiple GRNs by placing tetrode wires directly into the maxillary nerve. Third, we present a new system for delivering and monitoring, with high temporal precision, pulses of different tastants. These methods allow the characterization of neuronal responses in vivo directly from GRNs before, during and after tastants are delivered. We provide examples of voltage traces recorded from multiple GRNs, and present an example of how a spike sorting technique can be applied to the data to identify the responses of individual neurons. Finally, to validate our recording approach, we compare extracellular recordings obtained from GRNs with tetrodes to intracellular recordings obtained with sharp glass electrodes.

We present three new methods to study gustatory coding. Using a simple animal, the moth Manduca sexta (Manduca), we describe a dissection protocol, the use of extracellular tetrodes to record the activity of multiple gustatory receptor neurons, and a system for delivering and monitoring precisely timed pulses of tastants.

The sense of taste allows animals to detect chemicals in the environment, giving rise to behaviors critical for survival. When Gustatory Receptor Neurons ...

Visualization of Motor Axon Navigation and Quantification of Axon Arborization In Mouse Embryos Using Light Sheet Fluorescence Microscopy

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in vertebrates. Thus, it is critical to uncover the molecular mechanisms of how motor axons navigate to, arborize, and innervate their peripheral muscle targets during development and degeneration. Although transgenic Hb9::GFP mouse lines have long served to visualize motor axon trajectories during embryonic development, detailed descriptions of the full spectrum of axon terminal arborization remain incomplete due to the pattern complexity and limitations of current optical microscopy. Here, we describe an improved protocol that combines light sheet fluorescence microscopy (LSFM) and robust image analysis to qualitatively and quantitatively visualize developing motor axons. This system can be easily adopted to cross genetic mutants or MN disease models with Hb9::GFP lines, revealing novel molecular mechanisms that lead to defects in motor axon navigation and arborization.

Here, we describe a protocol for visualizing motor neuron projection and axon arborization in transgenic Hb9::GFP mouse embryos. After immunostaining for motor neurons, we used light sheet fluorescence microscopy to image embryos for subsequent quantitative analysis. This protocol is applicable to other neuron navigation processes in the central nervous system.

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in ...

Using Optical Coherence Tomography and Optokinetic Response As Structural and Functional Visual System Readouts in Mice and Rats

Optical coherence tomography (OCT) is a fast, non-invasive, interferometric technique allowing high-resolution retinal imaging. It is an ideal tool for the investigation of processes of neurodegeneration, neuroprotection and neuro-repair involving the visual system, as these often correlate well with retinal changes. As a functional readout, visually evoked compensatory eye and head movements are commonly used in experimental models involving the visual function. Combining both techniques allows a quantitative in vivo investigation of structure and function, which can be used to investigate the pathological conditions or to evaluate the potential of novel therapeutics. A great benefit of the presented techniques is the possibility to perform longitudinal analyses allowing the investigation of dynamic processes, reducing variability and cuts down the number of animals needed for the experiments. The protocol described aims to provide a manual for acquisition and analysis of high quality retinal scans of mice and rats using a low cost customized holder with an option to deliver inhalational anesthesia. Additionally, the proposed guide is intended as an instructional manual for researchers using optokinetic response (OKR) analysis in rodents, which can be adapted to their specific needs and interests.

A detailed protocol for the assessment of structural and visual readouts in rodents by optical coherence tomography and optokinetic response is presented. The results provide valuable insights for ophthalmologic as well as neurologic research.

Optical coherence tomography (OCT) is a fast, non-invasive, interferometric technique allowing high-resolution retinal imaging. It is an ideal tool for ...