Ringraziamo il Dr. S. Stella e Helen Vuong per contributi al protocollo di imaging del calcio. Ringraziamo Fogli Dr. K. per girare le scene di intervista. Ringraziamo il Dr. Arlene Hirano per i suoi commenti sul manoscritto. Questo progetto di ricerca e sviluppo è stata condotta da presso la David Geffen School of Medicine presso la UCLA autori ed è reso possibile da un accordo di contratto che è stato assegnato e gestito dal Medical Research e Materiel Command dell&#39;Esercito degli Stati Uniti (USAMRMC) e la Telemedicina &amp; Advanced Technology Research Center (TATRC), a Fort Detrick, nel Maryland sotto Numero del contratto: W81XWH-10-2-0077. Il supporto per questi studi è arrivato anche dal NIH EY04067 e una recensione Merito VA (NB). BCN è un VA Career Research Scientist.

Tutti gli esperimenti sono stati eseguiti in conformità con le linee guida per il benessere degli animali da esperimento emesse dalla politica US Public Health Service on Human Care e uso di animali da laboratorio e la University of California-Los Angeles (UCLA) comitato per la ricerca degli animali. Sono stati utilizzati Maschio e femmina adulto ratti Sprague-Dawley (Charles River Lab, Wilmington, MA) tra l&#39;età di 3-5 settimane. 1. animali e tessuti Preparazione Wholemount Retina e Immunoistochimica protocollo <ol><li> Preparare i seguenti materiali e strumenti: un microscopio da dissezione, 2 pinze con punte molto fini, forbici, carta da filtro di cellulosa, pipetta di plastica e un vetrino da microscopio. </li><li> Euthanize il topo in una camera chiusa da anestetizzare profondamente l&#39;animale con il 1-3% isoflurano seguita da decapitazione con una ghigliottina. Rimuovere gli occhi con un paio di forbici iris e posto in una capsula di Petri contenente la soluzione extracellulare. Hibernate A, Ames Mesono raccomandati dium o soluzioni fisiologiche. </li><li> [Passo Facoltativo se riempimento di RGCs con Fluo-4 è desiderato]. Eseguire l&#39;etichettatura Fluo-4 come descritto nei passaggi 2,3-2,4. </li><li> Utilizzando il microscopio da dissezione (intensità della luce: 1,6 x 10 8 fotoni / mm 2 ⋅sec), rimuovere la cornea tagliando la parte anteriore del bulbo oculare. Rimuovere la lente e vitreo dalla superficie retinica interna con una pinza. Per rimuovere il vitreo, stabilizzare il bulbo oculare tenendo la sclera saldamente con una pinza. Rimuovere delicatamente la base del vitreo verso il centro della retina con l&#39;altra pinza. La preparazione in questa fase si chiama oculare, che viene utilizzato per criosezioni. Maggiori informazioni su criosezioni possono essere trovati nei riferimenti 14,15. </li><li> Rimuovere la retina dalla oculare. Quindi, fare quattro tagli per consentire la retina per distesi. Montare delicatamente la retina su un vetrino da microscopio con il fotorecettore livello verso l&#39;alto. Aggiungere una goccia di soluzione alla retina e mettere cecarta da filtro llulose sulla retina. Una volta che la retina si attacca alla carta da filtro, posizionare la retina posteriore in soluzione. Se necessario, appiattire la retina con una spazzola o pinze. </li><li> Posizionare le retine wholemounted in PFA 4% per 10-15 minuti per il fissaggio. </li><li> Lavare le retine wholemounted tre volte per 30 min in tampone fosfato 0,1 M (PB), pH 7.4. Bloccare le retine con il 5% di siero di capra normale o siero asino in 0,1 PB contenente 0,3% Triton X-100 e 0,1% NaN 3 a 4 ° C durante la notte. Si consiglia un volume finale di 500 ml per tutti i passi per salvare le soluzioni di blocco e anticorpi. </li><li> Il giorno dopo, incubare le wholemounts retine con le primarie di anticorpi 5-7 giorni a 4 ° C. Diluizioni ottimali devono essere determinati dall&#39;utente. </li><li> Lavare le retine 3 x 30 min in PB 0.1 M e incubare una notte a 4 ° C nel corrispondente anticorpo secondario fluoroforo coniugato diretto contro le specie del anticorpo primario (concentrazione 1: 1.000). </li><li> Dopo tre lavaggi finali di 30 minuti ciascuno con PB, montare le retine di mezzo di montaggio. Sigillare il coprioggetto con smalto per lo stoccaggio prolungato. Conservare i campioni a 4 ° C e proteggere dalla luce. </li></ol> 2 Etichettatura delle cellule gangliari e degli assoni in Rat Wholemount retine con un calcio colorante indicatore <ol><li> Preparare 1.000 ml di mammiferi Ringer contenente (in mM) 125 NaCl, KCl 3, 2 CaCl 2, 1,25 NaH 2 PO 4, 1 MgCl2, 25 NaHCO3 e 10 glucosio bolliti con 95% O 2/5% di CO &#173; 2. </li><li> Eseguire la dissezione, come descritto nella procedura 1.2-1.4. </li><li> Per caricare le cellule gangliari retiniche (RGC) e dei loro assoni con un indicatore di calcio colorante, iniettare 0,5 ml di Fluo-4 sale pentapotassico (40 mM magazzino in H 2 O) nel moncone del nervo ottico di circa 1 mm posteriormente al bulbo oculare con una siringa . Per misurare gli aumenti dinamici in cellule gangliari [Ca 2 + </sup&gt;] ho un indicatore con alta affinità, come Fluo-4 con il suo K d di 345 nm, è ottimale. Fluo-4 offre l&#39;ulteriore vantaggio di avere una altissima efficienza quantica con un conseguente aumento delle emissioni di&gt; 100 volte quando si lega al calcio. </li><li> Mettere il paraocchi in mammiferi di Ringer bollito con il 95% O 2/5% di CO &#173; 2 per 1 ora a temperatura ambiente al buio. </li></ol> 3. Imaging di calcio Protocollo per cellule gangliari retiniche e assoni. <ol><li> Rimuovere l&#39;occhio, cristallino e vitreo come descritto nei passaggi 1,1-1,4. Isolare la retina dalla oculare e dividere in quadranti. Mount lato cellule gangliari un quadrante su un vetrino e utilizzare una griglia fetta arpa per stabilizzarlo. Mantenere gli altri pezzi dark-adattato in mammiferi di Ringer bollito con il 95% O 2/5% di CO &#173; 2 su ghiaccio per un uso successivo. </li><li> Superfuse camera di registrazione con la soluzione di Ringer e mammiferimantenere la soluzione ribolle continuamente con il 95% O 2/5% di CO 2. </li><li> Immagine il tessuto al microscopio. Condurre esperimenti a temperatura ambiente (~ 23 ° C) o raggiungono temperature fisiologiche riscaldando il palco, riscaldando il bagno d&#39;acqua sotto il campione o l&#39;applicazione di aria calda sulla superficie del campione. Nota: E &#39;importante notare che molte funzioni cellulari sono regolate dalla temperatura, che svolge un ruolo chiave nel mantenimento dell&#39;omeostasi intracellulare 16. Tuttavia, l&#39;introduzione di misure di riscaldamento può aumentare il tasso di photobleaching, evaporazione della deriva medio e fuoco causata dall&#39;espansione termica 17. L&#39;uso della temperatura ambiente diminuisce intracellulare compartimentalizzazione di Fluo-4 18. </li><li> Eseguire un controllo di due K + impulsi alti appaiati in assenza di farmaci. Depolarizzare RGCs e assoni RGC aumentando la [K +] o da 3 mm a 60 mm per 33 secondi durante ogni impulso per attivareVGCCs con un sistema di superfusione guidato otto gravità canale. Ridurre Na + da 57 mm per mantenere isosmolarity nella soluzione di elevata K +. </li><li> Valutare il contributo delle diverse VGCCs al segnale di calcio con l&#39;uso di bloccanti generali o specifici del canale Ca. Ad esempio, la riduzione del segnale calcio dopo la somministrazione di un non-specifico bloccante dei canali del calcio, cobalto, purché una misura semi-quantitativa del contributo dei VGCCs all&#39;alta K + segnale calcio -evoked. </li><li> Acquisire i valori di intensità di fluorescenza posizionando una regione di interesse (ROI) intorno alle RGC di interesse (Figura 2). </li><li> Normalizza la variazione di intensità di fluorescenza prodotta dal secondo alta K + picco alla variazione prodotta dalla prima alta K + picco. Poi, per la sperimentazione di specifici bloccanti dei canali del calcio, farmaci applicare solo nel corso del secondo alto K + impulso di una coppia e normalizzare questo picco controil primo valore di picco. Per misurare l&#39;effetto del farmaco in alto K + picco, dividere l&#39;ampiezza del secondo picco K + da quella del primo. L&#39;analisi deve essere eseguita su questi valori rispetto ai loro controlli corrispondenti derivati ​​dal accoppiato alta K + picchi misurata in assenza di farmaco. </li><li> Acquisire immagini a intervalli di 5 sec. Per evitare foto-sbiancamento, mantenere l&#39;eccitazione laser più basso possibile. Fornire eccitazione dalla linea 488 nm del laser argon, mentre il tubo fotomoltiplicatore raccoglie l&#39;emissione fluorescente attraverso un filtro LP 505 nm. </li></ol>

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In questo articolo, abbiamo descritto due diverse tecniche: 1) L&#39;immunoistochimica per mostrare Fluo-4 localizzazione delle cellule gangliari della retina in wholemounts, e 2) Calcio Imaging per analizzare le dinamiche del calcio nelle cellule gangliari retiniche e dei loro assoni. Immunoistochimica utilizzando wholemounts è stato utilizzato per rivelare la localizzazione delle proteine ​​nei roditori retina 20-23. Tuttavia, ci sono alcune limitazioni. La qualità della c...

Cellule gangliari retiniche (RGC) esprimono L, N-, P / Q e T-tipo VGCC come determinato attraverso il blocco farmacologico di queste componenti della cellula intera Ca canale corrente 1,2. VGCC sono proteine ​​transmembrana multimerici che sono coinvolte nel rilascio del trasmettitore, la trascrizione del gene, regolazione cellulare e sinaptica plasticità 3,4,5. VGCCs funzionali sono costituiti da almeno tre classi distinte di subunità: grandi, transmembrana α 1 formano pori subunità che stabiliscono proprietà biofisiche e farmacologiche del canale, α ausiliario principalmente extracellulare 2 subunità δ e subunità β intracellulari. Gli ultimi due complessi di forma eteromerici con diverse subunità α 1 e alterano la cinetica gating e il traffico dei canali alla membrana plasmatica 6. Negli ultimi decenni, molte tecniche sono state impiegate per lo studio delle proteine ​​espresfissione, come la immunoistochimica, enzyme-linked test immunoenzimatico, analisi occidentale e citometria a flusso. Queste tecniche richiedono l&#39;uso di anticorpi specifici per l&#39;individuazione di una data proteina di interesse e forniscono strumenti potenti per la localizzazione e la distribuzione di proteine ​​specifiche nei diversi tessuti. Le tecniche utilizzate per rilevare e quantificare i livelli di espressione di mRNA di una particolare proteina come l&#39;analisi Northern blot, RT-PCR, real-time RT-PCR, ibridazione in situ, cDNA microarray e analisi di protezione della ribonucleasi forniscono un approccio alternativo quando gli anticorpi non sono facilmente livelli di espressione disponibile o se di una particolare proteina sono bassi 7. Tuttavia, una limitazione all&#39;uso di tali tecniche molecolari è l&#39;identificazione desiderata della sequenza genica. Per localizzare proteine ​​nella retina, immunoistochimica può essere eseguita su retine wholemount. A causa della accessibilità dei RGCs, la wholemountpreparazione fornisce una piattaforma eccellente per studiare la localizzazione di specifiche proteine ​​al somata RGC e dei loro assoni. Oltre alla loro localizzazione, alcune proprietà funzionali dei VGCCs in RGC sono evidenziabili attraverso l&#39;uso di tecniche di imaging calcio. Descriviamo un protocollo di imaging del calcio di etichettare selettivamente RGCs con un indicatore di calcio colorante per misurare la dinamica del calcio intracellulare. Il contributo di diversi VGCCs al segnale calcio in differenti compartimenti cellulari può essere isolata con l&#39;uso di specifici del sottotipo Ca bloccanti dei canali. Forse uno degli aspetti più positivi della tecnica di imaging del calcio qui descritta è la capacità di registrare simultaneamente e indipendentemente da più RGCs e dei loro assoni. Anche se molte tecniche fisiologiche, come ad esempio intera registrazione patch clamp cellulare, forniscono ad alta risoluzione temporale registrazioni delle correnti di membrana, il somatico o fonte assonale di thesE le correnti registrate non possono essere discriminati e registrazioni possono essere effettuate solo da un singolo neurone alla volta. Array multielettrodico (MEA) sono in grado di registrare simultaneamente punte da molte cellule, ma possono né rilevare né discriminare l&#39;attivazione di, ad esempio, diversi sottotipi di canali del calcio. MEAS preferenzialmente registrare da cellule che si trovano in prossimità di un dato elettrodo 8 e registrare da cellule che generano grandi picchi 9. Metodi di imaging ottici forniscono una strategia alternativa per consentire le registrazioni simultanee e indipendenti di intere popolazioni di cellule che possono essere integrate con le informazioni ottenute da microelettrodo singola cellula e la registrazione patch clamp e la registrazione MEA. Sebbene le tecniche di imaging del calcio qui descritti sono stati impiegati per studiare la dinamica del calcio di RGCs, patch clamp e MEA può essere utilizzato anche in parallelo per chiarire ulteriormente le correnti ioniche e spiking proprietà dei RGCs. <pclass = &quot;jove_content&quot;&gt; Dato che le cellule amacrine sfollati costituiscono circa il 60% della popolazione neuronale nello strato di cellule gangliari della retina di topo 10, il nostro obiettivo era quello di utilizzare una tecnica di carico che etichette selettivamente RGCs con un indicatore di calcio sintetico colorante in un preparazione wholemount. Sebbene coloranti sintetici indicatori di calcio offrono una piattaforma eccellente per lo studio della dinamica del calcio intracellulare, la sua diffusione è stata ostacolata dall&#39;incapacità di caricare efficacemente specifiche popolazioni di neuroni all&#39;interno di una data rete. Molte tecniche come la massa di carico 11 ed elettroporazione 8,12 sono stati eseguiti per caricare intere popolazioni di cellule, tuttavia, tali tecniche non discriminano tra i tipi cellulari specifici. Geneticamente codificati indicatori di calcio offrono la possibilità di etichettare selettivamente specifiche popolazioni di cellule, tuttavia, tali metodi richiedono la generazione di animali transgenici 13. La nostra tecnica descrive un metod di etichettare selettivamente RGCs nella preparazione wholemount tramite ottico iniezione moncone del nervo di un indicatore di calcio colorante. Nel loro insieme, le tecniche strutturali e fisiologiche descritte in questo articolo fornire una piattaforma per studiare la localizzazione e il contributo delle VGCCs al segnale calcio nel RGCs e dei loro assoni.

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			<td>Secondary antibody</td>
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			<td height="42" style="height:42px;width:216px;">RBPMS</td>
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			<td>A rabbit polyclonal antibody&#160;was generated against the N-terminus of the RBPMS&#160;polypeptide (RBPMS4-24), GGKAEKENTPSEANLQEEEVR, by a commercial vendor (ProSci, Poway, CA).</td>
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immunohistochemical and calcium imaging methods in wholemount rat retina

In questo documento si descrivono gli strumenti, reagenti, e le misure pratiche che sono necessarie per: 1) preparazione di successo di retine wholemount per immunoistochimica e, 2) Calcio Imaging per lo studio di tensione gated canali del calcio (VGCC) mediata segnalazione di calcio in retina cellule gangliari. Il metodo di imaging del calcio descriviamo questioni aggira in materia di non-specifico carico di cellule amacrine sfollati nello strato di cellule gangliari.

Immunomarcatura con anticorpi specifici fornisce una piattaforma per studiare la localizzazione di particolari proteine ​​di interesse nella retina e la tecnica di imaging calcio permette lo studio del contributo dei VGCCs verso le dinamiche di calcio nelle cellule gangliari retiniche e dei loro assoni. Utilizzando un anticorpo contro le RBPMS proteine ​​delle cellule gangliari (RNA binding protein con splicing multipla) che identifica selettivamente RGCs 19, siamo stati i...

Watch this Scientific Journal Video about Immunohistochemical and Calcium Imaging Methods in Wholemount Rat Retina at JoVE.com

Immunohistochemical and Calcium Imaging Methods in Wholemount Rat Retina

Immunoistochimica protocolli sono utilizzati per studiare la localizzazione di una specifica proteina nella retina. Tecniche di imaging di calcio sono impiegate per studiare le dinamiche del calcio nelle cellule gangliari retiniche e dei loro assoni.

Metodi di imaging immunoistochimici e di calcio in Wholemount Rat Retina

In this paper we describe the tools, reagents, and the practical steps that are needed for: 1) successful preparation of wholemount retinas for ...

immunohistochemical-calcium-imaging-methods-wholemount-rat

Research

JoVE Journal

Neuroscience

14.4K Views.  University of California, Los Angeles.  Immunoistochimica protocolli sono utilizzati per studiare la localizzazione di una specifica proteina nella retina. Tecniche di imaging di calcio sono impiegate per studiare le dinamiche del calcio nelle cellule gangliari retiniche e dei loro assoni. 

Video: Immunohistochemical and Calcium Imaging Methods in Wholemount Rat Retina

Functional Calcium Imaging in Developing Cortical Networks

A hallmark pattern of activity in developing nervous systems is spontaneous, synchronized network activity. Synchronized activity has been observed in intact spinal cord, brainstem, retina, cortex and dissociated neuronal culture preparations. During periods of spontaneous activity, neurons depolarize to fire single or bursts of action potentials, activating many ion channels. Depolarization activates voltage-gated calcium channels on dendrites and spines that mediate calcium influx. Highly synchronized electrical activity has been measured from local neuronal networks using field electrodes. This technique enables high temporal sampling rates but lower spatial resolution due to integrated read-out of multiple neurons at one electrode. Single cell resolution of neuronal activity is possible using patch-clamp electrophysiology on single neurons to measure firing activity. However, the ability to measure from a network is limited to the number of neurons patched simultaneously, and typically is only one or two neurons. The use of calcium-dependent fluorescent indicator dyes has enabled the measurement of synchronized activity across a network of cells. This technique gives both high spatial resolution and sufficient temporal sampling to record spontaneous activity of the developing network.
A key feature of newly-forming cortical and hippocampal networks during pre- and early postnatal development is spontaneous, synchronized neuronal activity (Katz &amp; Shatz, 1996; Khaziphov &amp; Luhmann, 2006). This correlated network activity is believed to be essential for the generation of functional circuits in the developing nervous system (Spitzer, 2006). In both primate and rodent brain, early electrical and calcium network waves are observed pre- and postnatally in vivo and in vitro (Adelsberger et al., 2005; Garaschuk et al., 2000; Lamblin et al., 1999). These early activity patterns, which are known to control several developmental processes including neuronal differentiation, synaptogenesis and plasticity (Rakic &amp; Komuro, 1995; Spitzer et al., 2004) are of critical importance for the correct development and maturation of the cortical circuitry.
In this JoVE video, we demonstrate the methods used to image spontaneous activity in developing cortical networks. Calcium-sensitive indicators, such as Fura 2-AM ester diffuse across the cell membrane where intracellular esterase activity cleaves the AM esters to leave the cell-impermeant form of indicator dye. The impermeant form of indicator has carboxylic acid groups which are able to then detect and bind calcium ions intracellularly.. The fluorescence of the calcium-sensitive dye is transiently altered upon binding to calcium. Single or multi-photon imaging techniques are used to measure the change in photons being emitted from the dye, and thus indicate an alteration in intracellular calcium. Furthermore, these calcium-dependent indicators can be combined with other fluorescent markers to investigate cell types within the active network.

Spontaneous activity of developing neuronal networks can be measured using AM-ester forms of calcium-sensitive indicator dyes. Changes in intracellular calcium, indicating neuronal activation, are detected as transient changes in indicator fluorescence with one- or two-photon imaging. This protocol can be adapted for a range of developmentally-dependent neuronal networks in vitro.

Calcio Imaging funzionale nello sviluppo di reti corticali

A hallmark pattern of activity in developing nervous systems is spontaneous, synchronized network activity. Synchronized activity has been observed in ...

Ricerca

Neuroscienze

Wholemount Immunohistochemistry for Revealing Complex Brain Topography

The repeated and well-understood cellular architecture of the cerebellum make it an ideal model system for exploring brain topography. Underlying its relatively uniform cytoarchitecture is a complex array of parasagittal domains of gene and protein expression. The molecular compartmentalization of the cerebellum is mirrored by the anatomical and functional organization of afferent fibers. To fully appreciate the complexity of cerebellar organization we previously refined a wholemount staining approach for high throughput analysis of patterning defects in the mouse cerebellum. This protocol describes in detail the reagents, tools, and practical steps that are useful to successfully reveal protein expression patterns in the adult mouse cerebellum by using wholemount immunostaining. The steps highlighted here demonstrate the utility of this method using the expression of zebrinII/aldolaseC as an example of how the fine topography of the brain can be revealed in its native three-dimensional conformation. Also described are adaptations to the protocol that allow for the visualization of protein expression in afferent projections and large cerebella for comparative studies of molecular topography. To illustrate these applications, data from afferent staining of the rat cerebellum are included.

Neural circuits are topographically organized into functional compartments with specific molecular profiles. Here, we provide the practical and technical steps for revealing global brain topography using a versatile wholemount immunohistochemical staining approach. We demonstrate the utility of the method using the well-understood cytoarchitecture and circuitry of cerebellum.

Immunoistochimica Wholemount per rivelare Topografia Cervello Complex

The repeated and well-understood cellular architecture of the cerebellum make it an ideal model system for exploring brain topography. Underlying its ...

In vivo Neuronal Calcium Imaging in C. elegans

The nematode worm C. elegans is an ideal model organism for relatively simple, low cost neuronal imaging in vivo. Its small transparent body and simple, well-characterized nervous system allows identification and fluorescence imaging of any neuron within the intact animal. Simple immobilization techniques with minimal impact on the animal's physiology allow extended time-lapse imaging. The development of genetically-encoded calcium sensitive fluorophores such as cameleon 1 and GCaMP 2 allow in vivo imaging of neuronal calcium relating both cell physiology and neuronal activity. Numerous transgenic strains expressing these fluorophores in specific neurons are readily available or can be constructed using well-established techniques. Here, we describe detailed procedures for measuring calcium dynamics within a single neuron in vivo using both GCaMP and cameleon. We discuss advantages and disadvantages of both as well as various methods of sample preparation (animal immobilization) and image analysis. Finally, we present results from two experiments: 1) Using GCaMP to measure the sensory response of a specific neuron to an external electrical field and 2) Using cameleon to measure the physiological calcium response of a neuron to traumatic laser damage. Calcium imaging techniques such as these are used extensively in C. elegans and have been extended to measurements in freely moving animals, multiple neurons simultaneously and comparison across genetic backgrounds. C. elegans presents a robust and flexible system for in vivo neuronal imaging with advantages over other model systems in technical simplicity and cost.

In vivo Neuronal Calcium Imaging in C. elegans

With its small transparent body, well-documented neuroanatomy and a host of amenable genetic techniques and reagents, C. elegans makes an ideal model organism for in vivo neuronal imaging using relatively simple, low-cost techniques. Here we describe single neuron imaging within intact adult animals using genetically encoded fluorescent calcium indicators.

In vivo imaging di calcio neuronale in C. elegans

The nematode worm C. elegans is an ideal model organism  for relatively simple, low cost neuronal imaging in vivo. Its small transparent body and simple, ...

Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based multicolor labeling is challenging, especially when utilized for assessing interrelations between target proteins in the tissue with a high fat content such as the central nervous system (CNS).
Our protocol represents a refinement of the standard immunolabeling technique particularly adjusted for detection of both structural and soluble proteins in the rat CNS and peripheral lymph nodes (LN) affected by neuroinflammation. Nonetheless, with or without further modifications, our protocol could likely be used for detection of other related protein targets, even in other organs and species than here presented.

We here present an optimized, detailed protocol for double immunostaining in formalin-fixed, paraffin-embedded rat central nervous system (CNS) and peripheral lymph node (LN) tissue sections.

Analisi immunoistochimica nel Sistema Nervoso Centrale e Periferico Rat linfa nodo del tessuto Sezioni

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based ...

Non-invasive Parenchymal, Vascular and Metabolic High-frequency Ultrasound and Photoacoustic Rat Deep Brain Imaging

Photoacoustics and high frequency ultrasound stands out as powerful tools for neurobiological applications enabling high-resolution imaging on the central nervous system of small animals. However, transdermal and transcranial neuroimaging is frequently affected by low sensitivity, image aberrations and loss of space resolution, requiring scalp or even skull removal before imaging. To overcome this challenge, a new protocol is presented to gain significant insights in brain hemodynamics by photoacoustic and high-frequency ultrasounds imaging with the animal skin and skull intact. The procedure relies on the passage of ultrasound (US) waves and laser directly through the fissures that are naturally present on the animal cranium. By juxtaposing the imaging transducer device exactly in correspondence to these selected areas where the skull has a reduced thickness or is totally absent, one can acquire high quality deep images and explore internal brain regions that are usually difficult to anatomically or functionally describe without an invasive approach. By applying this experimental procedure, significant data can be collected in both sonic and optoacoustic modalities, enabling to image the parenchymal and the vascular anatomy far below the head surface. Deep brain features such as parenchymal convolutions and fissures separating the lobes were clearly visible. Moreover, the configuration of large and small blood vessels was imaged at several millimeters of depth, and precise information were collected about blood fluxes, vascular stream velocities and the hemoglobin chemical state. This repertoire of data could be crucial in several research contests, ranging from brain vascular disease studies to experimental techniques involving the systemic administration of exogenous chemicals or other objects endowed with imaging contrast enhancement properties. In conclusion, thanks to the presented protocol, the US and PA techniques become an attractive noninvasive performance-competitive means for cortical and internal brain imaging, retaining a significant potential in many neurologic fields.

The present work describes a new protocol to perform non-invasive high-frequency ultrasound and photoacoustic based imaging on rat brain, to efficiently visualize deep subcortical regions and their vascular patterns by directing signals on skull foramina naturally present on animal cranium.

Non invasiva parenchimale, vascolare e metabolica ad alta frequenza ad ultrasuoni e fotoacustico Rat profonda Brain Imaging

Photoacoustics and high frequency ultrasound stands out as powerful tools for neurobiological applications enabling high-resolution imaging on the central ...

Transpupillary Two-Photon In Vivo Imaging of the Mouse Retina

The retina transforms light signals from the environment into electrical signals that are propagated to the brain. Diseases of the retina are prevalent and cause visual impairment and blindness. Understanding how such diseases progress is critical to formulating new treatments. In vivo&#160;microscopy in animal models of disease is a powerful tool for understanding neurodegeneration and has led to important progress towards treatments of conditions ranging from Alzheimer&#39;s disease to stroke. Given that the retina is the only central nervous system structure inherently accessible by optical approaches, it naturally lends itself towards in vivo imaging. However, the native optics of the lens and cornea present some challenges for effective imaging access.
This protocol outlines methods for in vivo two-photon imaging of cellular cohorts and structures in the mouse retina at cellular resolution, applicable for both acute- and chronic-duration imaging experiments. It presents examples of retinal ganglion cell (RGC), amacrine cell, microglial, and vascular imaging using a suite of labeling techniques including adeno-associated virus (AAV) vectors, transgenic mice, and inorganic dyes. Importantly, these techniques extend to all cell types of the retina, and suggested methods for accessing other cellular populations of interest are described. Also detailed are example strategies for manual image postprocessing for display and quantification. These techniques are directly applicable to studies of retinal function in health and disease.

In vivo imaging is a powerful tool for the study of biology in health and disease. This protocol describes transpupillary imaging of the mouse retina with a standard two-photon microscope. It also demonstrates different in vivoimaging methods to fluorescently label multiple cellular cohorts of the retina.

Transpupillare Due fotoni In vivo Imaging della retina del topo

The retina transforms light signals from the environment into electrical signals that are propagated to the brain. Diseases of the retina are prevalent ...

In vivo Calcium Imaging in Mouse Inferior Olive

Inferior olive (IO), a nucleus in the ventral medulla, is the only source of climbing fibers that form one of the two input pathways entering the cerebellum. IO has long been proposed to be crucial for motor control and its activity is currently considered to be at the center of many hypotheses of both motor and cognitive functions of the cerebellum. While its physiology and function have been relatively well studied on single-cell level in vitro, presently there are no reports on the organization of the IO network activity in living animals. This is largely due to the extremely challenging anatomical location of the IO, making it difficult to subject to conventional fluorescent imaging methods, where an optic path must be created through the entire brain located dorsally to the region of interest.
Here we describe an alternative method for obtaining state-of-the-art -level calcium imaging data from the IO network. The method takes advantage of the extreme ventral location of the IO and involves a surgical procedure for inserting a gradient-refractive index (GRIN) lens through the neck viscera to come into contact with the ventral surface of the calcium sensor GCaMP6s-expressing IO in anesthetized mice. A representative calcium imaging recording is shown to demonstrate the feasibility to record IO neuron activity after the surgery. While this is a non-survival surgery and the recordings must be conducted under anesthesia, it avoids damage to life-critical brainstem nuclei and allows conducting large variety of experiments investigating spatiotemporal activity patterns and input integration in the IO. This procedure with modifications could be used for recordings in other, adjacent regions of the ventral brainstem.

In vivo Calcium Imaging in Mouse Inferior Olive

We present a protocol to expose the brainstem of adult mouse from the ventral side. By using a gradient-refractive index lens with a miniature microscope, calcium imaging can be used to examine the activity of inferior olive neural somata in vivo.

In vivo Imaging del calcio nell'oliva inferiore del topo

Inferior olive (IO), a nucleus in the ventral medulla, is the only source of climbing fibers that form one of the two input pathways entering the ...

Brain Pericyte Calcium and Hemodynamic Imaging in Transgenic Mice In Vivo

Recent advances in protein biology and mouse genetics have made it possible to measure intracellular calcium fluctuations of brain cells in vivo and to correlate this with local hemodynamics. This protocol uses transgenic mice that have been prepared with a chronic cranial window and express the genetically encoded calcium indicator, RCaMP1.07, under the &#945;-smooth muscle actin promoter to specifically label mural cells, such as vascular smooth muscle cells and ensheathing pericytes. Steps are outlined on how to prepare a tail vein catheter for intravenous injection of fluorescent dyes to trace blood flow, as well as how to measure brain pericyte calcium and local blood vessel hemodynamics (diameter, red blood cell velocity, etc.) by two photon microscopy in vivo through the cranial window in ketamine/xylazine anesthetized mice. Finally, details are provided for the analysis of calcium fluctuations and blood flow movies via the image processing algorithms developed by Barrett et al. 2018, with an emphasis on how these processes can be adapted to other cellular imaging data.

Brain Pericyte Calcium and Hemodynamic Imaging in Transgenic Mice In Vivo

This protocol presents steps to acquire and analyze fluorescent calcium images from brain ensheathing pericytes and blood flow data from nearby blood vessels in anesthetized mice. These techniques are useful for studies of mural cell physiology and can be adapted to investigate calcium transients in any cell type.

Calcio dei periciti cerebrali e imaging emodinamico nei topi transgenici in vivo

Recent advances in protein biology and mouse genetics have made it possible to measure intracellular calcium fluctuations of brain cells in vivo and to ...

Subcellular Imaging of Neuronal Calcium Handling In Vivo

Calcium (Ca2+) imaging has been largely used to examine neuronal activity, but it is becoming increasingly clear that subcellular Ca2+ handling is a crucial component of intracellular signaling. The visualization of subcellular Ca2+ dynamics in vivo,&#160;where neurons can be studied in their native, intact circuitry, has proven technically challenging in complex nervous systems. The transparency and relatively simple nervous system of the nematode Caenorhabditis elegans enable the cell-specific expression and in vivo visualization of fluorescent tags and indicators. Among these are fluorescent indicators that have been modified for use in the cytoplasm as well as various subcellular compartments, such as the mitochondria. This protocol enables non-ratiometric Ca2+ imaging in vivo with a subcellular resolution that permits the analysis of Ca2+ dynamics down to the level of individual dendritic spines and mitochondria. Here, two available genetically encoded indicators with different Ca2+ affinities are used to demonstrate the use of this protocol for measuring relative Ca2+ levels within the cytoplasm or mitochondrial matrix in a single pair of excitatory interneurons (AVA). Together with the genetic manipulations and longitudinal observations possible in C. elegans, this imaging protocol may be useful for answering questions regarding how Ca2+ handling regulates neuronal function and plasticity.

Subcellular Imaging of Neuronal Calcium Handling In Vivo

The current methods describe a non-ratiometric approach for high-resolution, sub-compartmental calcium imaging in vivo in Caenorhabditis elegans using readily available genetically encoded calcium indicators.

Imaging subcellulare della manipolazione neuronale del calcio in vivo

Calcium (Ca2+) imaging has been largely used to examine neuronal activity, but it is becoming increasingly clear that subcellular Ca2+ handling is a ...

Imaging a due fotoni e calcio ad ampio campo nel collicolo superiore

Calcium Imaging in Mouse Superior Colliculus

The superior colliculus (SC), an evolutionarily conserved midbrain structure in all vertebrates, is the most sophisticated visual center before the emergence of the cerebral cortex. It receives direct inputs from ~30 types of retinal ganglion cells (RGCs), with each encoding a specific visual feature. It remains elusive whether the SC simply inherits retinal features or if additional and potentially de novo processing occurs in the SC. To reveal the neural coding of visual information in the SC, we provide here a detailed protocol to optically record visual responses with two complementary methods in awake mice. One method uses two-photon microscopy to image calcium activity at single-cell resolution without ablating the overlaying cortex, while the other uses wide-field microscopy to image the whole SC of a mutant mouse whose cortex is largely undeveloped. This protocol details these two methods, including animal preparation, viral injection, headplate implantation, plug implantation, data acquisition, and data analysis. The representative results show that the two-photon calcium imaging reveals visually evoked neuronal responses at single-cell resolution, and the wide-field calcium imaging reveals&#160;neural activity across the entire SC. By combining these two methods, one can reveal the neural coding in the SC at different scales, and such combination can also be applied to other brain regions.

Autore in primo piano: Svelare la codifica neurale e i meccanismi di elaborazione visiva nel collicolo superiore 

This protocol details the procedure for imaging calcium responses in the superior colliculus (SC) of awake mice, including imaging single-neuron activity with two-photon microscopy while leaving the cortex intact in wild-type mice, and imaging the entire SC with wide-field microscopy in partial-cortex mutant mice.

Imaging del calcio nel collicolo superiore del topo

The superior colliculus (SC), an evolutionarily conserved midbrain structure in all vertebrates, is the most sophisticated visual center before the ...