Os autores gostariam de agradecer ao Dr. Candace Hsieh para sugestões e assistência com técnicas de imagem e Doris Dr. Wu para a perícia no pinto anatomia do ouvido interno durante a embriogênese. Este trabalho foi financiado pela NSF IOS-0642346, NIH T32-DC010775, NIH T32-GM008620, NIH R01-DC010796, e GAANN DOE P200A120165.

1. Preparar os instrumentos de dissecação seguinte e Reagentes <ul><li> Fluido cerebrospinal artificial (aCSF; 130 mM de NaCl, 3 mM KCl, 1,2 mM de KH 2 PO 4, 20 mM de NaHCO3, 3 mM de HEPES, 10 mM de glicose, 2 mM de CaCl2, 1,3 mM MgSO4) infundida continuamente com 95% de O 2/5% CO 2, à temperatura ambiente. Para a perfusão, encher a 2/3 de 500 ml de boca larga frasco Nalgene com um buraco perfurado na tampa. Tanque vai ser ligado a um tubo de um borbulhador de vidro haste, que penetra o aCSF através do orifício na tampa do frasco. Regule a pressão para se obter um fluxo constante de bolhas que alcançam de cerca de 1/3 do líquido, mas não são suficientemente forte para provocar salpicos sobre o aro. Submerge 5 ml frascos de vidro (até 6) para dentro do frasco de Nalgene para separar amostras individuais uns dos outros e da turbulência do fluxo de gás. ACSF oxigenado deve ser, pelo menos, 20 min antes de qualquer incubação de tecidos. </li><li> Prato de dissecação pequeno silicone (35 mm x 10milímetro revestido Petri usando Sylgard elastômeros Kit) com dois pinos de dissecação colocados em poliestireno hexagonal pequena (47 fundo mm) pesam barco. </li><li> Dois ponta fina fórceps, um tip-fórceps curvo, numa proveta de 50 ml, e um recipiente para resíduos de tecidos. </li><li> Puxado micropipeta de vidro (1,2 OD / 0,9 ID) quebrado de aproximadamente 20-50 uM de abertura na ponta e preenchido com rodamina dextran amina (RDA, MW = 3000, Invitrogen) em uma solução de 6,25% com 0,4% de Triton X-100 em PBS . Anexar por tubos bem para picospritzer e estabilizar a micromanipulador. </li></ul> 2. Micro dissecção para revelar papila basilar no E8 4,5 <ol><li> Com pinças curvas, corte E8 embrião logo abaixo do tronco, colocando a cabeça diretamente sobre silicone revestido prato dissecção dentro pesar barco. </li><li> A utilização de pinos de dissecação, posicionar a cabeça com uma vista ventral de modo que o ouvido do lado de juros é um pouco visível, o cabeça ligeiramente inclinada dorsalmente e apontando 10-30 graus de distância da center (Figura 2A). Imediatamente proteger a cabeça com pinos. Se bilateral traçado é desejada, a cabeça do centro em 0 graus, ou uma visão completa ventral para que ambos os lados podem ser acessados. Da mesma forma, para uma injeção do lado esquerdo, fixar a cabeça de -10 a -30 graus do centro para o lado esquerdo é acessível. </li><li> Usando o copo de 50 ml, transferir 30 ml de aCSF oxigenado para o prato, totalmente submergindo o tecido. </li><li> Agarre cuidadosamente e descascar para baixo a mandíbula inferior utilizando uma pinça de ponta fina, em seguida, remover a pálpebra inferior do lado de interesse. </li><li> Remover o tecido vascular sobrejacente, incluindo qualquer paladar restante e garganta. Estes tecidos moles deverão descascar revelar a superfície lisa de desenvolver chondrocranium com as artérias vertebrais distintas na sua superfície. Até este ponto, a massa branca característica otoconial deve ser visível. </li><li> Dissecar cuidadosamente a pele ao redor do meato externo, cartilagem da articulação da mandíbula e do ouvido médio, deixando o emner ouvido intacto. Use a pinça para gentilmente cortar estas estruturas cartilaginosas. </li><li> Remover artérias vertebrais e acúmulo de sangue através de um movimento de varredura suave com as pontas finas fórceps. Sangue pode obscurecer vista e de coagulação pode ligar a abertura pipeta de injeção. </li><li> O ducto coclear com epitélio sensorial adjacente (papila basilar) e gânglio acústico encontra-se directamente por baixo do chondrocranium 6 e pode ser visualizada como uma projecção semelhante a dedo alongado que se prolonga a partir do ouvido interno ventralmente, com a ponta distal-mais (vértice) próximo do anterior linha média 5. Pode haver um pequeno agrupamento de sangue (vermelho) do dissecação e / ou calcificações otolíticos (branco) no vértice do ducto coclear (Figura 2B), que pode auxiliar na visualização. No ápice é a mácula lagenar, um adesivo sensitivo pensado para ser da função vestibular 7,8. </li></ol> 3. Rotulagem seletiva de CN VIII Auditivo Fibras <ol><li&gt; Coloque a pipeta de injeção perto da superfície do embrião na região da papila do ducto coclear e basilar. </li><li> Lentamente baixar a micropipeta a primeira punção do crânio. Esta região craniana é mais fino do que áreas adjacentes e requer menos força para penetrar. A micropipeta deve agora ser dentro do ducto coclear. Opcional: uma pequena injecção de rastreio corante pode ser feita aqui para ajudar a visualizar a papila basilar. </li><li> Sem reposicionar o micropipeta, continue baixando até ele apenas violações da fronteira profunda do ducto coclear (Figura 1). Realizar uma injecção e repetir em várias regiões ao longo do comprimento da papila basilar (Figuras 2C, 2D), excluindo a extremidade mais proximal onde a lagena vestibular está localizado. Com o picospritzer definido entre 10-30 psi, várias injeções são feitas. O volume do fluido injectado varia de corante, e depende do grau de rotulagem desejada. Cada injecção deverá resultar num corante fluorescente-laponto Beled de aproximadamente 200-400 um de diâmetro (Figura 2D). </li><li> Uma vez que a injecção está completa, utilize uma pinça para transecção da amostra acima do tronco cerebral e da utilização de uma pipeta de transferência para colocar a porção de caudal para um pequeno frasco dentro do recipiente de aCSF continuamente perfundidos com 95% O2 / 5% de CO 2. </li><li> Para cada embrião, 20-30 min para permitir a transferência de corantes, em função da distância do centro de rastreio desejado. </li><li> Remover o tecido e se preparar para cortes histológicos. No exemplo mostrado aqui, o tecido é imerso em paraformaldeído a 4% (em 1X PBS) durante a noite, de sacarose a 30% (em 1X PBS) durante a noite. </li></ol> 4. Contracoloração e Análise <ol><li> Contracoloração é útil para ajudar a orientar o observador a localização anatômica, bem como identificar as regiões de interesse particular. Um contracorante eficaz nesta preparação é de imunomarcação de neurofilamento (Figuras 1, 3B, 3E), o que fortemente l comabels axônios e permite a demarcação de vias axonais no SNC. </li><li> Análise deveria ser realizada por toda a região marcada, tal como as saliências podem estender várias centenas de microns ou mais ao longo do eixo rostro-caudal. Alguns exemplos de análises básicas são: taxas de erro de segmentação de tempo, e / ou alterar os padrões de divergência de projecção. RDA axónios marcados são visualizados no sistema nervoso periférico e central, com alta resolução (Figuras 3A, 3D). </li></ol>

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Estudos sobre o desenvolvimento precoce do nervo VIII têm sido limitada, em parte, devido à dificuldade em identificar os axônios embrionárias resultantes de gânglios distinto múltipla. Vários estudos exploraram os sinais moleculares orientadores auditivo e vestibular célula sensorial e destinos de células ganglionares durante o desenvolvimento precoce, 5,11,12 mas os processos que regulam a inervação central têm ainda a ser determinado. Relatórios de projeções das células ganglionares acústi...

<table border="1"><tbody><tr><td> Nome do reagente / Material </td><td> Companhia </td><td> Número de catálogo </td><td> Comentários </td></tr><tr><td> Poliestireno Pesar </td><td> Fisher Scientific </td><td> 02-202-101 </td><td></td></tr><tr><td> Prato de Petri, 35 X 10 mm </td><td> Fisher Scientific </td><td> 50820644 </td><td> Use para fazer prato dissecção de silicone </td></tr><tr><td> Sylgard Kit elastômero de silicone </td><td> Instrumentos de Precisão mundo </td><td> SYLG184 </td><td> Brasão Petri para fazer prato dissecção </td></tr><tr><td> Pinos de dissecação </td><td> Vário </td><td></td><td> Embrião mantém no local durante a dissecção </td></tr><tr><td> NaCL </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> KCl </td><td> Vário </td><td></td><td> parte da receita aCSF </td&gt; </tr><tr><td> KH 2 PO 4 </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> NaHCO3 </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> Glicose </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> CaCl 2 </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> MgSO4 </td><td> Vário </td><td></td><td> parte da receita aCSF </td></tr><tr><td> Recipiente para aCSF. Sugerem translúcido boca larga frasco de Nalgene, 500 ml (16 onças) com tampa. </td><td> CPLabSafety </td><td> QP-PLC-03717 </td><td> Abertura do orifício na parte superior da tampa para haste de vidro bubling penetrar líquido </td></tr><tr><td> Vazio 5 ml frasco de vidro ou frasco transparente e comparável </td><td> Farmacêutica americana Partners, Inc </td><td> 6332300105 </td><td&gt; Utilização durante a incubação aCSF para manter as amostras separadas umas das outras e do fluxo de borbulhamento </td></tr><tr><td> Tanque de carbogénio (95% O2 / 5% CO 2) ligada a um tubo de borbulhador </td><td> Vário </td><td></td><td> Anexar por tubulação para borbulhador haste de vidro para perfusão aCSF </td></tr><tr><td> Vidro tronco borbulhador </td><td> Vário </td><td></td><td> Para infundir carbogênio em aCSF </td></tr><tr><td> Curvo-ponta fórceps </td><td> Instrumentos de Precisão mundo </td><td> 501008 </td><td> Para remover a cabeça do embrião do ovo </td></tr><tr><td> Dois bem-ponta fórceps </td><td> Instrumentos de Precisão mundo </td><td> 501985 </td><td> Para micro-dissecção </td></tr><tr><td> 50 ml Proveta </td><td> vário </td><td></td><td></td></tr><tr><td> Rodamina Dextran Amine (RDA) </td><td> Invitrogen </td><td> vário </td><td> Fluorescente axônio traçador </td></tr><tr><td> Triton X-100 </td><td> ICN Biomedicals </td><td></td><td></td></tr><tr><td> Solução salina tamponada com fosfato, (1X PBS) </td><td> Vário </td><td></td><td> Reagente de laboratório padrão </td></tr><tr><td> Fina parede capilares de vidro, 1,2 OD, 0,9 ID 4 &quot;(100 mm) de comprimento </td><td> Instrumentos de Precisão mundo </td><td> TW120F-4 </td><td> Carregar com a RDA. Cada capilar faz duas micropipetas de vidro </td></tr><tr><td> Agulha / Pipetar extrator </td><td> David Kopf Instruments </td><td> Modelo 720 </td><td> Configurações usadas: Calor 16,4, 2,2 Solenóide </td></tr><tr><td> Picospritzer </td><td> Parker Instrumentation </td><td> vário </td><td> Anexar por tubos de vidro fino para micropipeta </td></tr><tr><td> Micromanipulador </td><td> Narishige </td><td> vário </td><td></td></tr><tr><td> Microscópio de dissecção com fluorescência </td><td> Vário </td><td></td><td></td&gt; </tr><tr><td> Paraformaldeído a 4% </td><td> Vário </td><td></td><td> Reagente de laboratório padrão </td></tr><tr><td> anticorpo anti-neurofilamento, opcional </td><td> Millipore </td><td> AB1991 </td><td> Siga o protocolo recomendado pelo fabricante histológica </td></tr><tr><td> Criostato e materiais associados para seccionamento </td><td> Leica </td><td> vário </td><td></td></tr><tr><td> Microscópio de epifluorescência para imagiologia </td><td> Zeiss, vários </td><td></td><td></td></tr></tbody></table>

selective tracing of auditory fibers in the avian embryonic vestibulocochlear nerve

O pintainho embrionário é um modelo largamente utilizado para o estudo das projecções periféricas e centrais de células ganglionares. No sistema auditivo, rotulagem seletiva de axônios auditivos dentro do nervo craniano VIII aumentaria o estudo do centro de desenvolvimento circuito auditivo. Esta abordagem é difícil porque múltiplos órgãos sensoriais do ouvido interno, contribuir para o nervo VIII 1. Além disso, os marcadores que distinguem de forma confiável auditivo versus grupos vestibulares de axónios no interior do nervo VIIIth aviária ainda têm de ser identificados. Vias auditivas e vestibulares não podem ser distinguidas funcionalmente em embriões precoces, como sensoriais evocadas respostas não estão presentes antes dos circuitos são formados. Centralmente projetando axônios VIII foram traçadas em alguns estudos, mas auditivo rotulagem axônio foi acompanhada de rotulagem de outros componentes do nervo VIII 2,3. Aqui, nós descrevemos um método para o rastreio anterógrada do gânglio acústico para selectivamente labeaxónios auditivas l dentro do nervo VIIIth desenvolvimento. Em primeiro lugar, após o esvaziamento parcial da região cefálica anterior de um embrião de pinto com 8 dias de imersão em fluido cerebrospinal artificial oxigenado, o ducto coclear é identificado por anatómicas. Em seguida, uma micropipeta de vidro fino puxado está posicionado para injectar uma pequena quantidade de rodamina dextran amina na região adesiva e profunda adjacente onde as células ganglionares acústicos estão localizados. Dentro de 30 minutos após a injeção, os axônios auditivas são rastreados centralmente na parte posterior do cérebro e posteriormente pode ser visualizado a seguir à preparação histológica. Este método proporciona uma ferramenta útil para estudos do desenvolvimento da formação periférica de circuito auditivo central.

Os componentes do nervo VIII e a anatomia do nervo em si são complexas e tortuosas (Figuras 1, 3). Seletivamente o rastreio fibras resultantes a partir de células do gânglio acústicos, os segmentos do nervo VIII, bem como aferentes auditivos primários dentro do tronco cerebral podem ser rastreados de forma limpa e distinguidos dos seus homólogos vestibulares (Figuras 2, 3). Do mesmo modo, esta técnica pode ser utilizada para estudar as projecções periféricas das células gangl...

Watch this Scientific Journal Video about Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve at JoVE.com

Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve

Aqui descrevemos uma técnica de microdissecção seguido de injeção de corante fluorescente no gânglio acústico de embriões de galinha cedo para rastreamento seletivo das fibras auditivas axônios no nervo e rombencéfalo.

Rastreamento seletiva de fibras no nervo auditivo embrionário aviária Vestibulococlear

The embryonic chick is a widely used model for the study of peripheral and central ganglion cell projections. In the auditory system, selective labeling ...

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Research

JoVE Journal

Neuroscience

9.1K visualizações.  University of California, Irvine. Aqui descrevemos uma técnica de microdissecção seguido de injeção de corante fluorescente no gânglio acústico de embriões de galinha cedo para rastreamento seletivo das fibras auditivas axônios no nervo e rombencéfalo.

Vídeo: Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve

Tissue Preparation and Immunostaining of Mouse Sensory Nerve Fibers Innervating Skin and Limb Bones

Detection and primary processing of physical, chemical and thermal sensory stimuli by peripheral sensory nerve fibers is key to sensory perception in animals and humans. These peripheral sensory nerve fibers express a plethora of receptors and ion channel proteins which detect and initiate specific sensory stimuli. Methods are available to characterize the electrical properties of peripheral sensory nerve fibers innervating the skin, which can also be utilized to identify the functional expression of specific ion channel proteins in these fibers. However, similar electrophysiological methods are not available (and are also difficult to develop) for the detection of the functional expression of receptors and ion channel proteins in peripheral sensory nerve fibers innervating other visceral organs, including the most challenging tissues such as bone. Moreover, such electrophysiological methods cannot be utilized to determine the expression of non-excitable proteins in peripheral sensory nerve fibers. Therefore, immunostaining of peripheral/visceral tissue samples for sensory nerve fivers provides the best possible way to determine the expression of specific proteins of interest in these nerve fibers. So far, most of the protein expression studies in sensory neurons have utilized immunostaining procedures in sensory ganglia, where the information is limited to the expression of specific proteins in the cell body of specific types or subsets of sensory neurons. Here we report detailed methods/protocols for the preparation of peripheral/visceral tissue samples for immunostaining of peripheral sensory nerve fibers. We specifically detail methods for the preparation of skin or plantar punch biopsy and bone (femur) sections from mice for immunostaining of peripheral sensory nerve fibers. These methods are not only key to the qualitative determination of protein expression in peripheral sensory neurons, but also provide a quantitative assay method for determining changes in protein expression levels in specific types or subsets of sensory fibers, as well as for determining the morphological and/or anatomical changes in the number and density of sensory fibers during various pathological states. Further, these methods are not confined to the staining of only sensory nerve fibers, but can also be used for staining any types of nerve fibers in the skin, bones and other visceral tissue.

Immunocytochemical identification of peripheral sensory nerve fiber subtypes (and detection of protein expression therein) are key to the understanding of molecular mechanisms underlying peripheral sensation. Here we describe methods for preparation of peripheral/visceral tissue samples, such as skin and limb bones, for specific immunostaining of peripheral sensory nerve fibers.

Preparação do tecido e imunocoloração de Fibras nervosas sensoriais que inervam rato da Pele e Ossos Limb

Detection and primary processing of physical, chemical and thermal sensory stimuli by peripheral sensory nerve fibers is key to sensory perception in ...

Neurociência

A Lightweight, Headphones-based System for Manipulating Auditory Feedback in Songbirds

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and sensorimotor plasticity1. Consistent sensory perturbations result in compensatory changes in motor output, reflecting changes in feedforward motor control that reduce the experienced feedback error. By quantifying how different sensory feedback errors affect human behavior, prior studies have explored how visual signals are used to recalibrate arm movements2,3 and auditory feedback is used to modify speech production4-7. The strength of this approach rests on the ability to mimic naturalistic errors in behavior, allowing the experimenter to observe how experienced errors in production are used to recalibrate motor output.
Songbirds provide an excellent animal model for investigating the neural basis of sensorimotor control and plasticity8,9. The songbird brain provides a well-defined circuit in which the areas necessary for song learning are spatially separated from those required for song production, and neural recording and lesion studies have made significant advances in understanding how different brain areas contribute to vocal behavior9-12. However, the lack of a naturalistic error-correction paradigm - in which a known acoustic parameter is perturbed by the experimenter and then corrected by the songbird - has made it difficult to understand the computations underlying vocal learning or how different elements of the neural circuit contribute to the correction of vocal errors13.
The technique described here gives the experimenter precise control over auditory feedback errors in singing birds, allowing the introduction of arbitrary sensory errors that can be used to drive vocal learning. Online sound-processing equipment is used to introduce a known perturbation to the acoustics of song, and a miniaturized headphones apparatus is used to replace a songbird's natural auditory feedback with the perturbed signal in real time. We have used this paradigm to perturb the fundamental frequency (pitch) of auditory feedback in adult songbirds, providing the first demonstration that adult birds maintain vocal performance using error correction14. The present protocol can be used to implement a wide range of sensory feedback perturbations (including but not limited to pitch shifts) to investigate the computational and neurophysiological basis of vocal learning.

We describe the design and assembly of miniaturized headphones suitable for replacing a songbird&#x2019;s natural auditory feedback with a manipulated acoustic signal. Online sound processing hardware is used to manipulate song output, introduce real-time errors in auditory feedback via the headphones, and drive vocal motor learning.

Um leve, sistema de fones baseado para manipular feedback auditivo em Songbirds

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and ...

Optogenetic Stimulation of the Auditory Nerve

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted deaf subjects1-6. Nonetheless, sound coding with current CIs has poor frequency and intensity resolution due to broad current spread from each electrode contact activating a large number of SGNs along the tonotopic axis of the cochlea7-9. Optical stimulation is proposed as an alternative to electrical stimulation that promises spatially more confined activation of SGNs and, hence, higher frequency resolution of coding. In recent years, direct infrared illumination of&#160;the cochlea has been used to evoke responses in the auditory nerve10. Nevertheless it requires higher energies than electrical stimulation10,11 and uncertainty remains as to the underlying mechanism12. Here we describe a method based on optogenetics to stimulate SGNs with low intensity blue light, using transgenic mice with neuronal expression of channelrhodopsin 2 (ChR2)13 or virus-mediated expression of the ChR2-variant CatCh14. We used micro-light emitting diodes (&#181;LEDs) and fiber-coupled lasers to stimulate ChR2-expressing SGNs through a small artificial opening (cochleostomy) or the round window. We assayed the responses by scalp recordings of light-evoked potentials (optogenetic auditory brainstem response: oABR) or by microelectrode recordings from the auditory pathway and compared them with acoustic and electrical stimulation.

Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.

A estimulação optogenética do nervo auditivo

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted ...

Conditional Genetic Transsynaptic Tracing in the Embryonic Mouse Brain

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits during embryonic maturation of the brain however is technically challenging because most transsynaptic tracing methods developed to date depend on stereotaxic tracer injection. To overcome this problem, we developed a binary genetic strategy for conditional genetic transsynaptic tracing in the mouse brain. Towards this end we generated two complementary knock-in mouse strains to selectively express the bidirectional transsynaptic tracer barley lectin (BL) and the retrograde transsynaptic tracer Tetanus Toxin fragment C from the ROSA26 locus after Cre-mediated recombination. Cell-specific tracer production in these mice is genetically encoded and does not depend on mechanical tracer injection. Therefore our experimental approach is suitable to study neural circuit formation in the embryonic murine brain. Furthermore, because tracer transfer across synapses depends on synaptic activity, these mouse strains can be used to analyze the communication between genetically defined neuronal populations during brain development at a single cell resolution. Here we provide a detailed protocol for transsynaptic tracing in mouse embryos using the novel recombinant ROSA26 alleles. We have utilized this experimental technique in order to delineate the neural circuitry underlying maturation of the reproductive axis in the developing female mouse brain.

Capitalizing on a binary genetic strategy we provide a detailed protocol for neural circuit tracing in mice that express complementary transsynaptic tracers after Cre-mediated recombination. Because cell-specific tracer production is genetically encoded, our experimental approach is suitable to study the formation and maturation of neural circuitry during murine embryonic brain development at a single cell resolution.

Condicional Genetic transsináptica Tracing no Embryonic do cérebro do rato

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits ...

Laser-guided Neuronal Tracing In Brain Explants

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake through electroporation in brain explants with targeted laser illumination and matching filter goggles during the procedure. The described technique of in vitro electroporation by itself yields relatively good visual control for targetting certain areas of the brain. By combining it with laser excitation of fluorescent genetic markers and their read-out through band-passing filter goggles, which can pick up the emissions of the genetically labeled cells/nuclei and the fluorescent tracing dye, a researcher can substantially increase the accuracy of injections by finding the area of interest and controlling for the dye-spread/uptake in the injection area much more efficiently. In addition, the laser illumination technique allows to study the functionality of a given neurocircuit by providing information about the type of neurons projecting to a certain area in cases where the GFP expression is linked to the type of transmitter expressed by a subpopulation of neurons.

We describe a technique to label neurons and their processes via anterograde or retrograde tracer injections into brain nuclei using an in vitro preparation. We modified an existing method of in vitro tracer electroporation by taking advantage of fluorescently labeled mouse mutants and basic optical equipment in order to increase labeling accuracy.

Neuronal Tracing em explantes cérebro guiadas a laser

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake ...

Three-dimensional Imaging and Analysis of Mitochondria within Human Intraepidermal Nerve Fibers

The goal of this protocol is to study mitochondria within intraepidermal nerve fibers. Therefore, 3D imaging and analysis techniques were developed to isolate nerve-specific mitochondria and evaluate disease-induced alterations of mitochondria in the distal tip of sensory nerves. The protocol combines fluorescence immunohistochemistry, confocal microscopy and 3D image analysis techniques to visualize and quantify nerve-specific mitochondria. Detailed parameters are defined throughout the procedures in order to provide a concrete example of how to use these techniques to isolate nerve-specific mitochondria. Antibodies were used to label nerve and mitochondrial signals within tissue sections of skin punch biopsies, which was followed by indirect immunofluorescence to visualize nerves and mitochondria with a green and red fluorescent signal respectively. Z-series images were acquired with confocal microscopy and 3D analysis software was used to process and analyze the signals. It is not necessary to follow the exact parameters described within, but it is important to be consistent with the ones chosen throughout the staining, acquisition and analysis steps. The strength of this protocol is that it is applicable to a wide variety of circumstances where one fluorescent signal is used to isolate other signals that would otherwise be impossible to study alone.

This protocol uses three-dimensional (3D) imaging and analysis techniques to visualize and quantify nerve-specific mitochondria. The techniques are applicable to other situations where one fluorescent signal is used to isolate a subset of data from another fluorescent signal.

Imagem tridimensional e análise de mitocôndrias dentro as fibras nervosas intraepidérmicas humana

The goal of this protocol is to study mitochondria within intraepidermal nerve fibers. Therefore, 3D imaging and analysis techniques were developed to ...

Imaging Serotonergic Fibers in the Mouse Spinal Cord Using the CLARITY/CUBIC Technique

Long descending fibers to the spinal cord are essential for locomotion, pain perception, and other behaviors. The fiber termination pattern in the spinal cord of the majority of these fiber systems have not been thoroughly investigated in any species. Serotonergic fibers, which project to the spinal cord, have been studied in rats and opossums on histological sections and their functional significance has been deduced based on their fiber termination pattern in the spinal cord. With the development of CLARITY and CUBIC techniques, it is possible to investigate this fiber system and its distribution in the spinal cord, which is likely to reveal previously unknown features of serotonergic supraspinal pathways. Here, we provide a detailed protocol for imaging the serotonergic fibers in the mouse spinal cord using the combined CLARITY and CUBIC techniques. The method involves perfusion of a mouse with a hydrogel solution and clarification of the tissue with a combination of clearing reagents. Spinal cord tissue was cleared in just under two weeks, and the subsequent immunofluorescent staining against serotonin was completed in less than ten days. With a multi-photon fluorescent microscope, the tissue was scanned and a 3D image was reconstructed using Osirix software.

Supraspinal projections are important for pain perception and other behaviors, and serotonergic fibers are one of these fiber systems. The present study focused on the application of the combined CLARITY/CUBIC protocol to the mouse spinal cord in order to investigate the termination of these serotonergic fibers.

Imagiologia Fibras Serotoninérgicos na medula espinhal mouse usando o CLARIDADE / Técnica CUBIC

Long descending fibers to the spinal cord are essential for locomotion, pain perception, and other behaviors. The fiber termination pattern in the spinal ...

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats

Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory bowel diseases and diabetes. Here, we describe a protocol for the in vitro characterization of the electrophysiological properties of colonic afferents in rats. The colorectum, with the intact pelvic ganglion (PG) attached, is removed from the rat; superfused with carbogenated Krebs solution in the recording chamber; and cannulated at the oral and anal ends to allow for distension. A fine nerve bundle emanating from the PG is identified, and the multiunit afferent nerve activity is recorded using a suction electrode. Distension of the colonic segment elicits gradual increases in multiunit discharge. A principal component analysis is conducted to differentiate the low-threshold, the high-threshold, and the wide-dynamic range afferent fibers. Chemical sensitivity of colonic afferents can be studied through the bath or intraluminal administration of test compounds. This protocol can be modified for application to other species, such as mice and guinea pigs, and to study the differences in the electrophysiological properties of thoracolumbar/hypogastric and lumbosacral/pelvic afferents of the descending colon in normal and pathological conditions.

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats

Abnormal sensory function underlies visceral pain and other symptoms of functional and inflammatory bowel diseases. A protocol for the electrophysiological recording of the colonic afferent nerves in an ex vivo rat colorectum preparation is presented here.

In Vitro Caracterização das propriedades eletrofisiológicas das fibras aferentes do cólon em ratos

Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory ...

Retrograde Neuroanatomical Tracing of Phrenic Motor Neurons in Mice

Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic nerves innervating the respiratory diaphragm. In spinal cord slices, phrenic motor neurons cannot be identified from other motor neurons on morphological or biochemical criteria. We provide the description of procedures for visualizing phrenic motor neuron cell bodies in mice, following intrapleural injections of cholera toxin subunit beta (CTB) conjugated to a fluorophore. This fluorescent neuroanatomical tracer has the ability to be caught up at the diaphragm neuromuscular junction, be carried retrogradely along the phrenic axons and reach the phrenic cell bodies. Two methodological approaches of intrapleural CTB delivery are compared: transdiaphragmatic versus transthoracic injections. Both approaches are successful and result in similar number of CTB-labeled phrenic motor neurons. In conclusion, these techniques can be applied to visualize or quantify the phrenic motor neurons in various experimental studies such as those focused on the diaphragm-phrenic circuitry.

Here, we describe a protocol for identifying phrenic motor neurons in mice after intrapleural delivery of fluorophore conjugated cholera toxin subunit beta. Two techniques are compared to inject the pleural cavity: transdiaphragmatic versus transthoracic approaches.

Rastreamento neuroanatômica retrógrado do frênico neurônios em ratos

Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic ...

Targeting Alpha Synuclein Aggregates in Cutaneous Peripheral Nerve Fibers by Free-floating Immunofluorescence Assay

To date, for most neurodegenerative diseases only a post-mortem histopathological definitive diagnosis is available. For Parkinson&#39;s disease (PD), the diagnosis still relies only on clinical signs of motor involvement that appear later on in the disease course, when most of the dopaminergic neurons are already lost. Hence, there is a strong need for a biomarker that can identify patients at the beginning of disease or at the risk of developing it. Over the last few years, skin biopsy has proved to be an excellent research and diagnostic tool for peripheral nerve diseases such as small fiber neuropathy. Interestingly, a small fiber neuropathy and alpha synuclein (&#945;Syn) neural deposits have been shown by skin biopsy in PD patients. Indeed, skin biopsy has the great advantage of being an easily accessible, minimally invasive and painless procedure that allows the analysis of peripheral nervous tissue prone to the pathology. Moreover, the possibility of repeating the skin biopsy in the course of the follow-up of the same patient allows studying the longitudinal correlation with the disease progression. We set up a standardized reliable protocol to investigate the presence of &#945;Syn aggregates in skin nerve fibers of the PD patient. This protocol involves few short fixation steps, a cryotome sectioning and then a free-floating immunofluorescence double-staining with two specific antibodies: anti Protein Gene Product 9.5 (PGP9.5) to mark the cutaneous nerve fibers and anti 5G4 for detecting &#945;Syn aggregates. It is a versatile, sensitive and easy to perform protocol that can also be applied for targeting other proteins of interest in skin nerves. The ability to mark &#945;Syn aggregates is another step forward to the use of skin biopsy as a tool for establishing a pre-mortem histopathological diagnosis of PD.

Here, we present a protocol for a free-floating indirect immunofluorescence assay on skin biopsy sections that allows for the identification of disease specific conformation variants of alpha synuclein involved in Parkinson disease and multiple proteins of the peripheral nervous system.

Segmentação de agregados Alpha synuclein em fibras nervosas periféricas cutâneas por ensaio de imunofluorescência livre-flutuante

To date, for most neurodegenerative diseases only a post-mortem histopathological definitive diagnosis is available. For Parkinson&#39;s disease (PD), the ...