עבודה זו נתמכה על ידי מימון מן המכון הלאומי לבריאות (מענקים R21 ו R01 NS45037 ES014901).

<ol>
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Neurosci. 14, 203-215 (1996).</li><li>Lein, P., Johnson, M., Guo, X., Rueger, D., Higgins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Osteogenic+protein-1+induces+dendritic+growth+in+rat+sympathetic+neurons.">Osteogenic protein-1 induces dendritic growth in rat sympathetic neurons.</a> Neuron. 15, 597-605 (1995).</li><li>Lein, P. J., Higgins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laminin+and+a+basement+membrane+extract+have+different+effects+on+axonal+and+dendritic+outgrowth+from+embryonic+rat+sympathetic+neurons+in+vitro.">Laminin and a basement membrane extract have different effects on axonal and dendritic outgrowth from embryonic rat sympathetic neurons in vitro.</a> 136, 330-345 (1989).</li><li>Higgins, D., Lein, P. J., Osterhout, D. J., Johnson, M. I., Banker, G., Goslin, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Culturing Nerve Cells. , 177-295 (1991).</li><li>Beck, H. N., Drahushuk, K., Jacoby, D. B., Higgins, D., Lein, P. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glia+induce+dendritic+growth+in+cultured+sympathetic+neurons+by+modulating+the+balance+between+bone+morphogenetic+proteins+(BMPs)+and+BMP+antagonists.">Glia induce dendritic growth in cultured sympathetic neurons by modulating the balance between bone morphogenetic proteins (BMPs) and BMP antagonists.</a> J. Neurosci. 22, 10377-10387 (2002).</li><li>Higgins, D., Lein, P., Osterhout, D., Johnson, M. I., Banker, G., Goslin, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Culturing Nerve Cells. , 177-205 (1991).</li><li>Bruckenstein, D. A., Higgins, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+differentiation+of+embryonic+rat+sympathetic+neurons+in+tissue+culture.+II.+Serum+promotes+dendritic+growth.">Morphological differentiation of embryonic rat sympathetic neurons in tissue culture. II. Serum promotes dendritic growth.</a> Dev. Biol. 128, 337-348 (1988).</li></ol>

החוקרים אין לי מה לחשוף.

היתרונות של מודל זה הם: (א) תרבויות מורכבות של אוכלוסייה הומוגנית של נוירונים אוהדים חסרי סוגי תאים אחרים 17,23 (ב) גורם הגדילה הדרישות של נוירונים הם אוהדים מבוססת היטב, אשר מאפשר את השימוש בינוני מוגדר, וכן מגוון של כלי התקשורת מוגדרים, מצעים לעבוד היטב לגידול ושמ...

<table border="1" style=";text-align:right;direction:rtl"><tbody><tr><td> שם מגיב </td><td> חברה </td><td> מספר קטלוגי </td><td> תגובות </td></tr><tr><td> זכוכית coverslips </td><td> Bellco </td><td> 1943-10012 </td><td> 12 עגול מ&quot;מ coverslip # 1 עובי, זכוכית הגרמני </td></tr><tr><td> בנט עצה pipets </td><td> Bellco </td><td> 1273-50003 </td><td></td></tr><tr><td> פולי-D-ליזין </td><td> סיגמא </td><td> P0899-100 מ&quot;ג </td><td> המניות פתרון 1 מ&quot;ג / מ&quot;ל </td></tr><tr><td> מים מזוקקים </td><td> Gibco </td><td> 15230 </td><td></td></tr><tr><td> בסדר מלקחיים Dumont לא. 4 ו 5 </td><td> מדע כלים עדינים (FST) </td><td> 11252-30 11241-30 </td><td></td></tr><tr><td> 20 מד מחטים </td><td> בקטון דיקינסון </td><td> 305176 </td><td></td></tr><tr><td> ליבוביץ של L-15 בינוני </td><td> Invitrogen </tד&gt; <td> 11415 </td><td></td></tr><tr><td> Collagenase </td><td> וורטינגטון </td><td> 4176 </td><td> 1 מ&quot;ג / מ&quot;ל </td></tr><tr><td> Dispase </td><td> רוש </td><td> 04942078001 </td><td> 5 מ&quot;ג / מ&quot;ל </td></tr><tr><td> האנק של פתרון מאוזן מלח (-Ca, מ&quot;ג) </td><td> Invitrogen </td><td> 14185-052 </td><td></td></tr><tr><td> DMEM נמוכה לגלוקוז </td><td> Invitrogen </td><td> 11885 </td><td></td></tr><tr><td> L-גלוטמין </td><td> Invitrogen </td><td> 25030 </td><td> 20 מ&quot;מ </td></tr><tr><td> אינסולין / transferrin / סלניום </td><td> Invitrogen </td><td> 51500-056 </td><td> 100x </td></tr><tr><td> שומן חומצה חינם BSA </td><td> Calbiochem </td><td> 126609 </td><td></td></tr><tr><td> NGF </td><td> הרלן Bioproducts </td><td> 5017 </td><td></td></tr><tr><td> חם בינוני F-12 מזין (F-12) </td><td> Invitrogen </td><td> 11765 </td><tד&gt; </td></tr><tr><td> ציטוסין arabinoside </td><td> סיגמא </td><td> C1768 </td><td></td></tr><tr><td> Matrigel </td><td> BD Biosciences </td><td> 356234 </td><td> למנוע הופעה חוזרת של ההקפאה, ההפשרה מחזורי </td></tr><tr><td> BMP-7 </td><td> R &amp; D מערכות Curis, Inc </td><td> 345-BP BMP7-07H </td><td> BMPs 4, 5 ו - 6 עובדים באותה מידה כמו גם BMP-7 ו לפעמים יותר קל להשיג באופן מסחרי </td></tr><tr><td> Paraformaldehyde </td><td> סיגמא </td><td> P6148 </td><td></td></tr><tr><td> טריטון X-100 </td><td> דיג </td><td> BP151-500 </td><td></td></tr><tr><td> עכבר נגד עכבר MAP2 נוגדן </td><td> שטרנברג Monoclonals בע&quot;מ </td><td> SMI52 </td><td> 1/5000 </td></tr><tr><td> Alexa פלואוריד 546 עז נגד העכבר </td><td> Invitrogen </td><td> A11003 </td><td> 1/10000 </td></tr><tr><td> הרכבה התקשורת </td><td> להאריך את בדיקות Antifade ערכת מולקולרית </td> &lt;td&gt; P7481 </td><td></td></tr></tbody></table>

inducing dendritic growth in cultured sympathetic neurons

הצורה של הדנדריטים ארבור קובע את הקלט הסינפטי הכולל תא עצב יכול לקבל 1-3, ומשפיע סוגי והפצה של תשומות אלה 4-6. דפוסי שינה של צמיחה הפלסטיות דנדריטים והן קשורות עם תפקוד לקוי neurobehavioral במודלים ניסיוניים 7, והם חשבו לתרום סימפטומים קליניים שנצפה בשתי 8-10 הפרעות התפתחותיות ומחלות ניווניות 11-13. תצפיות אלו מדגישים את החשיבות התפקודית של ויסות בדיוק מורפולוגיה הדנדריטים, וסבורים כי מנגנוני זיהוי השולטים הצמיחה הדנדריטים לא רק לקדם את ההבנה של כמה עצבי קישוריות מוסדר במהלך התפתחות תקינה, אבל עשויה גם לספק תובנות על אסטרטגיות טיפולית חדשנית למחלות נוירולוגיות שונות. מחקרים שיבדקו את המנגנונים של צמיחת הדנדריטים יהיה להקל במידה רבה על ידי זמינות Ofa מערכת מודל המאפשר נוירונים כדי לפעול באופן ניסיוני ממצב שבו הם לא להאריך דנדריטים אחד שבו הם לפרט ארבור הדנדריטים דומה לזה של עמיתיהם שלהם vivo. תרבויות העיקריות של נוירונים אוהדים הסתייגותם מן הגרעינים צוואר הרחם מעולה (SCG) של מכרסמים סביב הלידה לספק מודל כזה. כאשר בתרבית מוגדר בינוני בהעדר מתאי גליה בסרום ו ganglionic, הנוירונים אוהדים להאריך את תהליך יחיד אשר axonal, ואת זה המדינה חד קוטבי נמשכת שבועות עד חודשים בתרבות 14,15. עם זאת, תוספת של המוךפו&quot;גנטי שהולך או עצם חלבונים 7 (BMP-7) 16,17 או 18 Matrigel עד בינוני התרבות מפעילה נוירונים אלה כדי להרחיב את התהליכים רבים העונים על קריטריונים מורפולוגיים, ביוכימיים ופונקציונלי של דנדריטים. נוירונים אוהדים הסתייגותם מן SCG של מכרסמים סביב הלידה ו שגודלו בתנאים מוגדרים הם אוכלוסייה הומוגנית של נוירונים 19שמגיבים בצורה אחידה לפעילות דנדריט, קידום של Matrigel, BMP-7 ו BMPs אחרים של decapentaplegic (DPP) ו 60A subfamilies 17,18,20,21. חשוב לציין, Matrigel-BMP ו-Induced דנדריט היווצרות מתרחשת בהיעדר שינויים הישרדות התא או צמיחה axonal 17,18. כאן, נתאר כיצד להגדיר את תרבויות הסתייגותם של נוירונים אוהדים הנגזרות SCG של חולדות סביב הלידה, כך שהם מגיבים על פעילות דנדריט, קידום סלקטיבי של Matrigel או BMPs.

Watch this Scientific Journal Video about Inducing Dendritic Growth in Cultured Sympathetic Neurons at JoVE.com

Inducing Dendritic Growth in Cultured Sympathetic Neurons

אנו מתארים באמצעות פרוטוקול המוךפו&quot;גנטי שהולך העצם חלבונים 7 (BMP-7) או Matrigel סלקטיבי לגרום לצמיחה הדנדריטים בנוירונים אוהדים העיקריים הסתייגותם מן הגרעינים צוואר הרחם מעולה (SCG) של חולדות הלידה.

גרימת צמיחה הדנדריטים בנוירונים אוהדים מתורבתים

The shape of the dendritic arbor determines the total synaptic input a neuron can receive 1-3, and influences the types and distribution of these inputs ...

inducing-dendritic-growth-in-cultured-sympathetic-neurons

Research

JoVE Journal

Neuroscience

12.7K Views.  University of California, Davis. אנו מתארים באמצעות פרוטוקול המוךפו"גנטי שהולך העצם חלבונים 7 (BMP-7) או Matrigel סלקטיבי לגרום לצמיחה הדנדריטים בנוירונים אוהדים העיקריים הסתייגותם מן הגרעינים צוואר הרחם מעולה (SCG) של חולדות הלידה.

Video: Inducing Dendritic Growth in Cultured Sympathetic Neurons

Fluorescence Recovery After Photobleaching (FRAP) of Fluorescence Tagged Proteins in Dendritic Spines of Cultured Hippocampal Neurons

FRAP has been used to quantify the mobility of GFP-tagged proteins. Using a strong excitation laser, the fluorescence of a GFP-tagged protein is bleached in the region of interest. The fluorescence of the region recovers when the unbleached GFP-tagged protein from outside of the region diffuses into the region of interest. The mobility of the protein is then analyzed by measuring the fluorescence recovery rate. This technique could be used to characterize protein mobility and turnover rate.
In this study, we express the (enhanced green fluorescent protein) EGFP vector in cultured hippocampal neurons. Using the Zeiss 710 confocal microscope, we photobleach the fluorescence signal of the GFP protein in a single spine, and then take time lapse images to record the fluorescence recovery after photobleaching. Finally, we estimate the percentage of mobile and immobile fractions of the GFP in spines, by analyzing the imaging data using ImageJ and Graphpad softwares.
This FRAP protocol shows how to perform a basic FRAP experiment as well as how to analyze the data.

Fluorescence Recovery After Photobleaching FRAP of Fluorescence Tagged Proteins in Dendritic Spines of Cultured Hippocampal Neurons

FRAP has been used to quantify the mobility of Green Fluorescence Protein (GFP)-tagged proteins in cultured cells. We examined the mobile/immobile fractions of the GFP by analyzing the fluorescence recovery percentage after photobleaching. In this study, FRAP was performed at spines of hippocampal neurons.

שחזור הקרינה לאחר photobleaching (FRAP) של החלבונים המתויגים הקרינה הקוצים הדנדריטים של נוירונים בהיפוקמפוס Cultured

FRAP has been used to quantify the mobility of GFP-tagged proteins. Using a strong excitation laser, the fluorescence of a GFP-tagged protein is bleached ...

Analysis of Dendritic Spine Morphology in Cultured CNS Neurons

Dendritic spines are the sites of the majority of excitatory connections within the brain, and form the post-synaptic 
compartment of synapses. These structures are rich in actin and have been shown to be highly dynamic. In response to classical Hebbian plasticity 
as well as neuromodulatory signals, dendritic spines can change shape and number, which is thought to be critical for the refinement of neural 
circuits and the processing and storage of information within the brain. Within dendritic spines, a complex network of proteins link extracellular 
signals with the actin cyctoskeleton allowing for control of dendritic spine morphology and number. Neuropathological studies have demonstrated that 
a number of disease states, ranging from schizophrenia to autism spectrum disorders, display abnormal dendritic spine morphology or numbers. 
Moreover, recent genetic studies have identified mutations in numerous genes that encode synaptic proteins, leading to suggestions that these 
proteins may contribute to aberrant spine plasticity that, in part, underlie the pathophysiology of these disorders. In order to study the potential 
role of these proteins in controlling dendritic spine morphologies/number, the use of cultured cortical neurons offers several advantages. Firstly, 
this system allows for high-resolution imaging of dendritic spines in fixed cells as well as time-lapse imaging of live cells. Secondly, this in 
vitro system allows for easy manipulation of protein function by expression of mutant proteins, knockdown by shRNA constructs, or pharmacological 
treatments. These techniques allow researchers to begin to dissect the role of disease-associated proteins and to predict how mutations of these 
proteins may function in vivo.

Numerous recent studies have identified mutations in synaptic proteins associated with brain pathologies. Primary cultured cortical neurons offer great flexibility in examining the effects of these disease-associated proteins on dendritic spine morphology and motility.

ניתוח של מורפולוגיה השדרה דנדריטים של נוירונים במערכת העצבים המרכזית Cultured

Dendritic spines are the sites of the majority of excitatory connections within the brain, and form the post-synaptic 
compartment of synapses. These ...

Quantitative Analysis of Synaptic Vesicle Pool Replenishment in Cultured Cerebellar Granule Neurons using FM Dyes

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis. Retrieved SVs are then refilled with neurotransmitter and rejoin the recycling pool, defined as SVs that are available for exocytosis1,2. The recycling pool can generally be subdivided into two distinct pools - the readily releasable pool (RRP) and the reserve pool (RP). As their names imply, the RRP consists of SVs that are immediately available for fusion while RP SVs are released only during intense stimulation1,2. It is important to have a reliable assay that reports the differential replenishment of these SV pools in order to understand 1) how SVs traffic after different modes of endocytosis (such as clathrin-dependent endocytosis and activity-dependent bulk endocytosis) and 2) the mechanisms controlling the mobilisation of both the RRP and RP in response to different stimuli.
FM dyes are routinely employed to quantitatively report SV turnover in central nerve terminals3-8. They have a hydrophobic hydrocarbon tail that allows reversible partitioning in the lipid bilayer, and a hydrophilic head group that blocks passage across membranes. The dyes have little fluorescence in aqueous solution, but their quantum yield increases dramatically when partitioned in membrane9. Thus FM dyes are ideal fluorescent probes for tracking actively recycling SVs. The standard protocol for use of FM dye is as follows. First they are applied to neurons and are taken up during endocytosis (Figure 1). After non-internalised dye is washed away from the plasma membrane, recycled SVs redistribute within the recycling pool. These SVs are then depleted using unloading stimuli (Figure 1). Since FM dye labelling of SVs is quantal10, the resulting fluorescence drop is proportional to the amount of vesicles released. Thus, the recycling and fusion of SVs generated from the previous round of endocytosis can be reliably quantified.
Here, we present a protocol that has been modified to obtain two additional elements of information. Firstly, sequential unloading stimuli are used to differentially unload the RRP and the RP, to allow quantification of the replenishment of specific SV pools. Secondly, each nerve terminal undergoes the protocol twice. Thus, the response of the same nerve terminal at S1 can be compared against the presence of a test substance at phase S2 (Figure 2), providing an internal control. This is important, since the extent of SV recycling across different nerve terminals is highly variable11.
Any adherent primary neuronal cultures may be used for this protocol, however the plating density, solutions and stimulation conditions are optimised for cerebellar granule neurons (CGNs)12,13.

A live fluorescence imaging technique to quantify the replenishment and mobilisation of specific synaptic vesicle (SV) pools in central nerve terminals is described. Two rounds of SV recycling are monitored in the same nerve terminals providing an internal control.

ניתוח כמותי של רענון שלפוחיות Synaptic בריכת ב Cultured נוירונים גרגיר cerebellar באמצעות צבעים FM

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis.  Retrieved SVs are then refilled with ...

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.

המחקר הגנטי של הדור הבא אקסון עם נוירונים בתרבית למבוגרים הגנגליון הגב שורש

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

Voltage-sensitive Dye Recording from Axons, Dendrites and Dendritic Spines of Individual Neurons in Brain Slices

Understanding the biophysical properties and functional organization of single neurons and how they process information is fundamental for understanding how the brain works. The primary function of any nerve cell is to process electrical signals, usually from multiple sources. Electrical properties of neuronal processes are extraordinarily complex, dynamic, and, in the general case, impossible to predict in the absence of detailed measurements. To obtain such a measurement one would, ideally, like to be able to monitor, at multiple sites, subthreshold events as they travel from the sites of origin on neuronal processes and summate at particular locations to influence action potential initiation. This goal has not been achieved in any neuron due to technical limitations of measurements that employ electrodes. To overcome this drawback, it is highly desirable to complement the patch-electrode approach with imaging techniques that permit extensive parallel recordings from all parts of a neuron. Here, we describe such a technique - optical recording of membrane potential transients with organic voltage-sensitive dyes (Vm-imaging) - characterized by sub-millisecond and sub-micrometer resolution. Our method is based on pioneering work on voltage-sensitive molecular probes 2. Many aspects of the initial technology have been continuously improved over several decades 3, 5, 11. Additionally, previous work documented two essential characteristics of Vm-imaging. Firstly, fluorescence signals are linearly proportional to membrane potential over the entire physiological range (-100 mV to +100 mV; 10, 14, 16). Secondly, loading neurons with the voltage-sensitive dye used here (JPW 3028) does not have detectable pharmacological effects. The recorded broadening of the spike during dye loading is completely reversible 4, 7. Additionally, experimental evidence shows that it is possible to obtain a significant number (up to hundreds) of recordings prior to any detectable phototoxic effects 4, 6, 12, 13. At present, we take advantage of the superb brightness and stability of a laser light source at near-optimal wavelength to maximize the sensitivity of the Vm-imaging technique. The current sensitivity permits multiple site optical recordings of Vm transients from all parts of a neuron, including axons and axon collaterals, terminal dendritic branches, and individual dendritic spines. The acquired information on signal interactions can be analyzed quantitatively as well as directly visualized in the form of a movie.

An imaging technique for monitoring of membrane potential changes with sub-micrometer spatial and sub-millisecond temporal resolution is described. The technique, based on laser excitation of voltage-sensitive dyes, allows measurements of signals in axons and axon collaterals, terminal dendritic branches, and individual dendritic spines.

הקלטת דיי מתח רגישה מהאקסונים, הדנדריטים וקוצים הדנדריטים של נוירונים בודדים בפרוסות מוח

Understanding the biophysical properties and functional organization of single neurons and how they process information is fundamental for understanding ...

Imaging pHluorin-tagged Receptor Insertion to the Plasma Membrane in Primary Cultured Mouse Neurons

A better understanding of the mechanisms governing receptor trafficking between the plasma membrane (PM) and intracellular compartments requires an experimental approach with excellent spatial and temporal resolutions. Moreover, such an approach must also have the ability to distinguish receptors localized on the PM from those in intracellular compartments. Most importantly, detecting receptors in a single vesicle requires outstanding detection sensitivity, since each vesicle carries only a small number of receptors. Standard approaches for examining receptor trafficking include surface biotinylation followed by biochemical detection, which lacks both the necessary spatial and temporal resolutions; and fluorescence microscopy examination of immunolabeled surface receptors, which requires chemical fixation of cells and therefore lacks sufficient temporal resolution1-6 . To overcome these limitations, we and others have developed and employed a new strategy that enables visualization of the dynamic insertion of receptors into the PM with excellent spatial and temporal resolutions 7-17 . The approach includes tagging of a pH-sensitive GFP, the superecliptic pHluorin 18, to the N-terminal extracellular domain of the receptors. Superecliptic pHluorin has the unique property of being fluorescent at neutral pH and non-fluorescent at acidic pH (pH &lt; 6.0). Therefore, the tagged receptors are non-fluorescent when within the acidic lumen of intracellular trafficking vesicles or endosomal compartments, and they become readily visualized only when exposed to the extracellular neutral pH environment, on the outer surface of the PM. Our strategy consequently allows us to distinguish PM surface receptors from those within intracellular trafficking vesicles. To attain sufficient spatial and temporal resolutions, as well as the sensitivity required to study dynamic trafficking of receptors, we employed total internal reflection fluorescent microscopy (TIRFM), which enabled us to achieve the optimal spatial resolution of optical imaging (~170 nm), the temporal resolution of video-rate microscopy (30 frames/sec), and the sensitivity to detect fluorescence of a single GFP molecule. By imaging pHluorin-tagged receptors under TIRFM, we were able to directly visualize individual receptor insertion events into the PM in cultured neurons. This imaging approach can potentially be applied to any membrane protein with an extracellular domain that could be labeled with superecliptic pHluorin, and will allow dissection of the key detailed mechanisms governing insertion of different membrane proteins (receptors, ion channels, transporters, etc.) to the PM.

By tagging the extracellular domains of membrane receptors with superecliptic pHluorin, and by imaging these fusion receptors in cultured mouse neurons, we can directly visualize individual vesicular insertion events of the receptors to the plasma membrane. This technique will be instrumental in elucidating the molecular mechanisms governing receptor insertion to the plasma membrane.

הדמית pHluorin-תויגה הכנסת קולט לממברנה הפלזמה בנוירונים עכבר מתורבתים ראשיים

A better understanding of the mechanisms governing receptor trafficking between the plasma membrane (PM) and intracellular compartments requires an ...

Fast Micro-iontophoresis of Glutamate and GABA: A Useful Tool to Investigate Synaptic Integration

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of the dendritic tree, which eventually leads to neuronal output of action potentials at the axon. The influence of diverse spatial and temporal parameters of specific synaptic input on neuronal output is currently under investigation, e.g. the distance-dependent attenuation of dendritic inputs, the location-dependent interaction of spatially segregated inputs, the influence of GABAergig inhibition on excitatory integration, linear and non-linear integration modes, and many more.
With fast micro-iontophoresis of glutamate and GABA it is possible to precisely investigate the spatial and temporal integration of glutamatergic excitation and GABAergic inhibition. Critical technical requirements are either a triggered fluorescent lamp, light-emitting diode (LED), or a two-photon scanning microscope to visualize dendritic branches without introducing significant photo-damage of the tissue. Furthermore, it is very important to have a micro-iontophoresis amplifier that allows for fast capacitance compensation of high resistance pipettes. Another crucial point is that no transmitter is involuntarily released by the pipette during the experiment.
Once established, this technique will give reliable and reproducible signals with a high neurotransmitter and location specificity. Compared to glutamate and GABA uncaging, fast iontophoresis allows using both transmitters at the same time but at very distant locations without limitation to the field of view. There are also advantages compared to focal electrical stimulation of axons: with micro-iontophoresis the location of the input site is definitely known and it is sure that only the neurotransmitter of interest is released. However it has to be considered that with micro-iontophoresis only the postsynapse is activated and presynaptic aspects of neurotransmitter release are not resolved. In this article we demonstrate how to set up micro-iontophoresis in brain slice experiments.

In this article we introduce fast micro-iontophoresis of neurotransmitters as a technique to investigate integration of postsynaptic signals with high spatial and temporal precision.

מיקרו-Iontophoresis מהיר של גלוטמט וגאבא: כלי שימושי לחקירת האינטגרציה סינפטית

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of ...

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.

הדמיה קוצים הדנדריטים של העכברוש הראשי נוירונים בהיפוקמפוס באמצעות מובנה תאורה מיקרוסקופית

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

Quantification of Endosome and Lysosome Motilities in Cultured Neurons Using Fluorescent Probes

In the brain, membrane trafficking systems play important roles in regulating neuronal functions, such as neuronal morphology, synaptic plasticity, survival, and glial communications. To date, numerous studies have reported that defects in these systems cause various neuronal diseases. Thus, understanding the mechanisms underlying vesicle dynamics may provide influential clues that could aid in the treatment of several neuronal disorders. Here, we describe a method for quantifying vesicle motilities, such as motility distance and rate of movement, using a software plug-in for the ImageJ platform. To obtain images for quantification, we labeled neuronal endosome-lysosome structures with EGFP-tagged vesicle marker proteins and observed the movement of vesicles using a time-lapse microscopy. This method is highly useful and simplify measuring vesicle motility in neurites, such as axons and dendrites, as well as in the soma of both neurons and glial cells. Furthermore, this method can be applied to other cell lines, such as fibroblasts and endothelial cells. This approach could provide a valuable advancement of our understanding of membrane trafficking.

The investigation of membrane trafficking is crucial for understanding neuronal functions. Here, we introduce a method for quantifying vesicle motility in neurons. This is a convenient method that can be adapted to the quantification of membrane trafficking in the nervous system.

כימות של Endosome ו Lysosome Motilities ב נוירונים תרבותיים באמצעות בדיקות פלואורסצנטי

In the brain, membrane trafficking systems play important roles in regulating neuronal functions, such as neuronal morphology, synaptic plasticity, ...

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.