This work was supported by grants from the Pharmaceutical Research and Manufacturers Association of America (PhRMA) Foundation (to B. Gulbransen), National Institutes of Health (Building Interdisciplinary Research Careers in Women&#8217;s Health) grant K12 HD065879 (B. Gulbransen) and start-up funds from Michigan State University (B. Gulbransen).

NOTA: Los siguientes procedimientos que afectan el tejido de los animales de laboratorio son consistentes con las Directrices AVMA para la Eutanasia de los Animales de 2013 y fueron aprobados previamente por la Universidad Estatal de Michigan IACUC. 1. Preparación del tejido <ol><li> Anestesiar a la investigación con animales en una cámara que contiene 2,5% de isoflurano en oxígeno o mediante la colocación de 3-5 ml de isoflurano líquido sobre un material absorbente en el suelo de la cámara, asegurando que una barrera física impide que los animales del contacto directo con el isoflurano. Prueba para la profundidad de la anestesia por pellizcar la almohadilla de la pata. NOTA: La profundidad de la anestesia se considera apropiado cuando no hay reflejo de retirada de la extremidad posterior. Una vez anestesiado apropiadamente, la eutanasia el ratón por dislocación cervical </li><li> Colocar el animal en posición supina y limpiar la piel abdominal con etanol al 70%. El uso de fórceps para pellizcar la piel abdominal en la línea media y el uso de tijeras quirúrgicas para realizar una media de 6 cml incisión a lo largo de la línea alba para exponer los órganos digestivos internos. </li><li> El uso de fórceps romos para localizar y exponer el íleon dentro del peritoneo. Cortar el mesenterio del íleon / colon con tijeras y comenzar desentrañar el intestino. </li><li> Una vez que la longitud del intestino se deshizo adecuadamente, cortar el intestino distal al estómago y proximal al ciego para una preparación de íleon. Para una preparación de intestino grueso, cortar el distal del colon hasta el ciego y proximal al recto. </li><li> Quite rápidamente el segmento intestinal y colocarlo en un vaso con medio DMEM / F12 suplementado con hidrocloruro de nicardipina 3 M y 1 mM de clorhidrato escopolamina (en adelante, &quot;los medios de comunicación&quot;) en hielo. La adición de estos inhibidores facilita microdisección y la imagen posterior al paralizar el músculo liso intestinal. </li><li> Segmento de corte de interés (por ejemplo, yeyuno, íleon, colon distal o proximal) basado en marcadores anatómicos establecidos. Normalmente utilize tejido del íleon distal o en el colon distal. Sin embargo, utilizar el mismo procedimiento básico para aislar, de carga y de imagen neuronas y glía mientéricas en todas las regiones intestinales. </li><li> Retirar un pequeño segmento (6.4 cm) del segmento de intestino deseada y colocar en una placa de Petri con recubrimiento de Sylgard lleno de medios refrigerados. </li><li> Asegure los extremos proximal y distal del segmento intestinal con alfileres de insectos y abrir el tubo intestinal haciendo una recta, a lo largo corte a lo largo del borde mesentérico. </li><li> Tejido Pin plana bajo una ligera tensión con la cara mucosa y cuidadosamente diseccionar capa mucosa utilizando unas pinzas finas (# 5 y # 5/45 trabajo mejor) y tijeras muy finas de primavera. NOTA: La eliminación de la mucosa puede ser muy traumático para la ENS si no se hace correctamente. Para las preparaciones de calidad, tener cuidado de limitar retirada brusca de la mucosa por descamación o raspado. La mejor práctica es levantar la mucosa y cortar debajo con tijeras finas. </li><li> Cortar el tejido en preparación menors (aproximadamente 0,5 cm 2) y el pin en platos de imagen (4 esquinas con capa muscular circular hacia arriba) se coloca en el hielo con medio fresco. </li><li> Diseccionar cuidadosamente lejos músculo circular por las burlas aparte con pinzas finas para exponer el plexo mientérico. Evite estirar excesivo. </li><li> Coloque el plato de imágenes de nuevo en solución de hielo y el cambio por medio fresco. </li><li> Preparar 2 ml de mezcla de enzimas por plato [dispasa 1 U / ml (4,48 mg / 8 ml), colagenasa Tipo II 150 U / ml (5,45 mg / 8 ml) en los medios de comunicación]. </li><li> Sacar los recipientes de hielo y agregue la mezcla de enzimas del paso 1.13. </li><li> Incubar platos a TA durante 15 min con 5% de CO 2/95% de aire. </li><li> Preparaciones de tejidos de lavado con medios 3 veces y esquinas re-pin. </li></ol> 2. Carga Fluo-4 Tinte NOTA: Evite fotoblanqueo trabajando con luz limitada durante la manipulación de los tintes fluorescentes y tejido cargadas de tintes indicadores. <ol><li> Preparar 4 mM solución de carga de Fluo-4. <ol><li> Añadir 1,5 ml de medio y 1,2 l de una acción probenecid 250 mM a una alícuota de 1,5 l de 4 mM Fluo-4 stock. 4 mM Fluo-4 stock se prepara mediante la adición de 11,4 l de Pluronic F-127 (20% en DMSO; suplementado con 0,25% Cremaphor-EL) a 50 g de Fluo-4, AM. </li></ol></li><li> Incubar preparaciones en Fluo-4 solución de carga durante 45 minutos en una incubadora oscura a 37 ° C. </li><li> Eliminar de la incubadora y lavar las preparaciones con los medios de comunicación 3 veces. </li><li> Medios de cambio de medio que contenía 200 mM probenecid e incubar 15 min a 37 ° C antes de formación de imágenes. NOTA: El probenecid es un fármaco que inhibe transportistas resistencia a múltiples fármacos en las neuronas. La adición de este fármaco inhibe la capacidad de las neuronas para extruir tintes y mejora etiquetado neuronal. Carga masiva de Ca 2+ colorantes indicadores en ausencia de probenecid produce carga celular principalmente glial. La adición de probenecid permite la visualización de las respuestas neuronales y gliales. </li><li> Preparar Modificado Krebuffer de bs. <ol><li> Hacer un tampón de Krebs modificada de tal manera que las concentraciones finales (en mm) de los componentes son como sigue: 121 NaCl, 5,9 KCl, 2,5 CaCl 2, 1,2 MgCl2, 1,2 NaH 2 PO 4, 10 HEPES, 21,2 NaHCO 3, 1 pirúvico ácido y 8 de glucosa (pH ajustado a 7,4 con NaOH). Añadir 3 nicardipina mu M y 1 mM escopolamina para inhibir las contracciones musculares durante Ca 2 + de imágenes y todo el montaje disecciones. </li></ol></li></ol> 3. Imagen y Análisis NOTA: Utilice por lo menos un equipo básico de imágenes con una fuente de luz fluorescente, microscopio, una cámara CCD calidad y software de adquisición correspondiente. Varíe la adición de otros componentes en función de la fuente de luz y aplicación específica. Una rueda de filtro y de obturación deben usarse con una fuente de luz de arco de xenón tradicional. Sin embargo, fuentes de luz LED y sistemas de iluminación no requieren esos componentes. <ol><li> Coloque el recording cámara bajo el microscopio y el uso de un sistema de perfusión de flujo por gravedad con múltiples depósitos de jeringa con calefacción establecer una velocidad de perfusión continua de 2-3 ml / min de 37 ° C tampón Krebs. Asegúrese de que para evitar la formación de burbujas de aire, tanto en la línea de entrada y de succión conectado a una trampa de vacío. </li><li> Traiga el plexo deseados en foco bajo iluminación de campo brillante. Evitar la sobreexposición de los tejidos, que puede conducir a la foto de blanqueo. </li><li> Examine el Fluo-4 carga dentro de los ganglios y seleccione ganglios saludable para la imagen. Ganglios poco saludables / dañados exhibirán autofluorescencia o puntiforme morfología y no deben ser utilizados para la imagen. </li><li> Una vez que se selecciona ganglio, desviar la trayectoria de la luz a la cámara y obtener imágenes en vivo con el software de adquisición de imágenes. Asegúrese de que ganglio está en enfocar y ajustar la tasa de adquisición de imágenes y los tiempos de exposición. NOTA: las tasas de adquisición de la imagen y los tiempos pueden variar dependiendo de los eventos investigadores desean grabar. Para la mayoría de experimentos, las imágenestradicionalmente adquiridos en 0,5 a 1 Hz para las células gliales y hasta 2-10 Hz para las neuronas porque las respuestas glial Ca 2 + no son tan rápidos como Ca 2 + transitorios en las neuronas. </li><li> Comience experimento y establecer actividad de referencia durante 30 segundos. </li><li> Aplicar drogas pre-calentado de interés, tales como agonistas y antagonistas del receptor utilizando el sistema de perfusión de flujo por gravedad a una velocidad de 2-3 ml / min. Siga aplicación de agonistas / antagonistas volviendo a una perfusión de tampón normal y permitir un período de lavado / recuperación de al menos 10 min. NOTA: Los tiempos de aplicación del fármaco variará dependiendo del compuesto individual y el diseño experimental. En general, una aplicación de 20-30 segundos de agonista es suficiente para activar G-receptores acoplados a proteínas en las neuronas y células gliales. Sin embargo, los canales iónicos activados por ligando (tales como los receptores nicotínicos de la acetilcolina) requieren tiempos de aplicación de no más de 5-10 segundos. Otras exposiciones duración causarán ligando canales iónicos a Dese rápidamentensitize. Antagonistas deben aplicarse durante aproximadamente 3-15 minutos para asegurar el bloqueo completo de las vías de receptores. Sin embargo, esta es una generalización bruto y los investigadores siempre debe optimizar cualquier fármaco experimental en su paradigma particular. </li><li> Detener la grabación y vista la película de lapso de tiempo del experimento. Seleccionar cuidadosamente las regiones de interés (ROI) utilizando el software de análisis de imagen correspondiente. </li><li> Utilice el software para normalizar y compara ROI intensidad fluorescente en contra de su valor inicial fluorescente línea de base. Los cambios en la fluorescencia normalizada son directamente proporcionales a los cambios en [Ca2 +]. <ol><li> Utilice una modificación de un método descrito anteriormente utilizando 26? F / F = ((F 1 - F 0) / F 0) ROI - ((F 1 - F 0) / F 0) de fondo, donde F1 es la fluorescencia en cualquier dado punto y F0 es la fluorescencia de línea de base, para mejorar la precisión de evaluación. Esto ayuda modificaciónen la reducción de ruido de los cambios de fluorescencia en preparaciones de tejidos que exhiben movimiento de la capa muscular subyacente en el plexo mientérico. </li></ol></li></ol>

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The authors have nothing to disclose.

The methodologies described in this manuscript provide a consistent approach to effectively study neurons and enteric glia in the ENS. Although imaging neurons and enteric glia in culture has yielded a wealth of insight into the function of individual cells, studying these cells in their native, multi-cellular environment is crucial for our understanding their physiology and pathophysiology. Fluorescence microscopy is a crucial technique for assessing multidirectional interactions of cells in the ENS. Loading cells of the ENS with selective fluorescent markers and image acquisition with high-resolution microscopy permits quantitative observations of cellular activity in the ENS. Imaging live tissue samples of the ENS is performed relatively quickly and generates large amounts of in-depth functional and spatial data. Mouse myenteric and submucosal plexus preparations used in these experiments allow for molecular and genetic manipulation approaches. Ca2+ imaging in whole-mount preparations provides a useful tool for the assessment of neuron-glia interactions.
In advanced experimental paradigms, several probes can be combined to obtain information about different events within the cells. Fluorescence microscopy can record images with enhanced contrast of specific molecules, if an appropriate fluorescent label is used. Fluo-4 was chosen because it possesses a large dynamic range. Sufficient incubation time is vital when using the AM dyes in ENS. Dye concentration and loading method may need to be adjusted to achieve best results. Ideal preparations should be loaded with sufficient dye to visualize changes in fluorescence but not so much so that the dye chelates the target ions and interferes with intracellular signaling. Exposure to fluorescent light should be limited to prevent phototoxicity in cells and photobleaching of dyes. 
Investigators must be careful with several steps of this experiment, especially solution and tissue preparation. Particular care has to be taken during processing and dissection of ENS tissue in order to maintain cellular functions. The GI tract contains several layers and tissue varieties, which pose challenges for dissection and imaging quality in these whole-mount preparations 27. Furthermore, the interconnecting fiber tracts of the MP are wider and ganglia are larger than those of the SMP 2. The neuronal density of the myenteric plexus is higher compared to that of the submucosal plexus 28. Slow and imprecise dissections will have detrimental effects on the quality of the plexus preparations and thus the overall success of the experiments. Therefore, clean/undamaged tools, practice and manual dexterity are critical to this procedure. 
In whole-mount tissue preparations, careful consideration should be taken when drawing the regions of interest (ROI) to correctly assess the kinetics and degree of observed change in fluorescence intensity of the desired cell type. As the ganglia are located on a contractile muscle layer, motion artifacts caused by gut motility are a primary concern during in situ imaging. Thus, suppressing these motion disturbances through re-pinning tissue preparations after incubation with enzymes and the addition of pharmacological inhibition (nicardipine/scopolamine) to buffers permits clear and reliable image acquisition. Aside from pharmacology and mechanical approaches to prevent tissue movement, recent studies illustrate the application of advanced software methodologies and cell type response characteristics to correct for residual tissue movement in the recordings and improve the accuracy of analysis 29. Barring these technical hurdles, this method provides physiologically relevant conditions to assess morphologic and quantitative characteristics of neurons and enteric glia in the ENS.

El sistema nervioso entérico (SNE) se organiza en dos plexos ganglionares incrustados dentro de la pared del tubo digestivo 1. Estos circuitos neuronales intramusculares, el plexo mientérico (MP) y el plexo submucoso (SMP), se componen de neuronas y glía entérica (Figura 1) 2. El MP y SMP regulan gastrointestinales (GI) funciones tales como la motilidad intestinal y la absorción del epitelio y secreción, respectivamente 3. Glía entérica se encuentran en las proximidades de las neuronas en los ganglios, pero las poblaciones de la glía entérica también existen dentro de la interconexión de los tractos de fibras y porciones extra-ganglionares de la pared intestinal 3,4. Glia entéricas se creía originalmente para proporcionar sólo un apoyo nutritivo para las neuronas. Sin embargo, estudios recientes sugieren fuertemente que las interacciones neurona-glía son esenciales para ENS funciona 5,6. Por ejemplo, los datos muestran que la glía entérica &quot;escuchar&quot; a la actividad neuronal 7y modular los circuitos neuronales 6,8, proteger a las neuronas entéricas del estrés oxidativo 9 y son capaces de generar nuevas neuronas entéricas en respuesta a la lesión 10,11. El protocolo presentado en esta revisión técnica proporciona un método simple y robusto para examinar la compleja interacción entre las neuronas y la glía entérica utilizando in situ intracelular de Ca 2 + de imágenes. Ca 2+ es una molécula de señalización ubicua en las células excitables y juega un papel esencial en los eventos de señalización sináptica en el sistema nervioso 12. La excitación de las neuronas o glía entérica provoca una elevación de la concentración citoplasmática de Ca2 +, ya sea por afluencia a través de canales de Ca2 + permeables o Ca 2 + liberación de las reservas de calcio intracelular. Imagen Ca 2 + transitorios en las neuronas y glía con tintes fluorescentes es un establecidos y técnica ampliamente utilizada para estudiar la organización funcional y dinámica deel 13-17 ENS. Formación de imágenes de Ca 2+ ha demostrado ser una herramienta importante en el estudio de los segmentos de tejido GI intactas para dilucidar la propagación de la excitabilidad a través de redes de marcapasos ICC 18 y músculo liso intestinal 19,20. Se permite a los investigadores para investigar un amplio espectro de parámetros fisiológicos y proporciona información acerca tanto a su distribución espacial y dinámica temporal. Las células se pueden teñir de manera eficiente en una forma mínimamente invasiva mediante el uso de indicadores fluorescentes de membrana permeable y protocolos de tinción optimizados 21. Esto ofrece la oportunidad de controlar un gran número de neuronas y glía entérica en preparaciones funcionalmente conservados 14-16,22, así como in vivo 23. -Todo el montaje preparaciones de tejidos son a granel cargado con una alta afinidad de Ca2 + colorante indicador como Fluo-4 que aumenta su fluorescencia cuando se une a Ca 2+. Los cambios en la fluorescencia se registran por una cámara CCD y analyzed digitalmente 6. El advenimiento de Ca 2+ proporcionó la oportunidad de supervisar las neuronas y células gliales interacciones, la capacidad de respuesta a diversos estímulos, y la participación de estos tipos de células en los procesos gastrointestinales en tiempo real. In situ imagen Ca 2+ ha dado una gran comprensión de los mecanismos de señalización de las neuronas entéricas y glía y posee varias ventajas sobre los modelos de cultivo celular de 6,24. En primer lugar, in situ preparaciones mantener el entorno de la matriz nativa de las neuronas y glia y salen de la mayor parte de sus conexiones con el tejido diana intacta. En segundo lugar, la genética y la morfología de la glía entérica culta significativamente se alteran en comparación con 6,24 en vivo. En tercer lugar, muchas interacciones heterotípicas se pierden en cultivo de células primarias y esto limita la evaluación de las interacciones célula-célula. Aunque las células cultivadas son muy adecuadas para la investigación de las propiedades fundamentales, su usefulness para el estudio de las interacciones complejas entre células gliales y las neuronas entéricas es limitado. La investigación de la interacción neurona-glía utilizando un enfoque in situ es fisiológicamente más relevantes como las vías sinápticas permanecen intactos 25. En comparación con los enfoques de cultivo celular, un enfoque in situ ofrece mejores condiciones para comprender sistemáticamente las intrincadas interacciones entre neuronas y glía entérica. Por otra parte, la organización planar del plexo ganglionares en los preparativos de todo el montaje es ideal para imágenes fluorescentes de intracelular de Ca 2 + transitorios y esta técnica ofrece un enfoque sencillo para evaluar la actividad neuronal glía en la ENS.

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in situ ca2+ imaging of the enteric nervous system

Reflex behaviors of the intestine are controlled by the enteric nervous system (ENS). The ENS is an integrative network of neurons and glia in two ganglionated plexuses housed in the gut wall. Enteric neurons and enteric glia are the only cell types within the enteric ganglia. The activity of enteric neurons and glia is responsible for coordinating intestinal functions. This protocol describes methods for observing the activity of neurons and glia within the intact ENS by imaging intracellular calcium (Ca2+) transients with fluorescent indicator dyes. Our technical discussion focuses on methods for Ca2+ imaging in whole-mount preparations of the myenteric plexus from the rodent bowel. Bulk loading of ENS whole-mounts with a high-affinity Ca2+ indicator such as Fluo-4 permits measurements of Ca2+ responses in individual neurons or glial cells. These responses can be evoked repeatedly and reliably, which permits quantitative studies using pharmacological tools. Ca2+ responses in cells of the ENS are recorded using a fluorescence microscope equipped with a cooled charge-coupled device (CCD) camera. Fluorescence measurements obtained using Ca2+ imaging in whole-mount preparations offer a straightforward means of characterizing the mechanisms and potential functional consequences of Ca2+ responses in enteric neurons and glial cells.

El uso adecuado de esta técnica permite a los investigadores para medir con precisión Ca2 + intracelular [Ca 2 +] i transitorios en las neuronas entéricas y glía en todo el montaje en preparaciones de tejido. Un ejemplo representativo de un agonista-evocó Ca 2 + respuestas en glía dentro de un ganglio mientérico del colon de ratón se muestra en Video 1. Los resultados siguientes están destinados a ilustrar algunos resultados representativos que hemos obtenido usando este método. En primer lugar, la figura 2 ilustra los resultados de un experimento que mide la glía entérica [Ca 2 +] i los cambios en la respuesta a la estimulación por el ATP dentro de los preparativos de cobaya colon plexo mientérico muscular longitudinal (LMMP). Específicamente, esta figura muestra el método para el análisis adecuado del protocolo experimental enumerados anteriormente, incluyendo el contorno de la ganglionares y asteriscos denotan la localización de las neuronas entéricas mientérico analizado. Estos resultados tambiénllustrate la dosis óptima de un centenar de ATP micromolar en la movilización de [Ca 2 +] i en el conejillo de indias glía mientérico. Esta respuesta puede ser utilizado para calibrar la estimulación glial entérico y normalizar las respuestas para poner a prueba los estímulos. A continuación, la Figura 3 aclara cómo seleccionar adecuadamente las regiones de interés (ROI) que rodea las células gliales, que se muestra y la zona círculos amarillos. Estos resultados también muestran los cambios de fluorescencia deseados bajo condiciones basales y en respuesta a estímulos farmacológicos. Finalmente, la figura 4 muestra las consideraciones espaciales para la elección de la glía entérica y neuronas de [Ca 2 +] i en las respuestas de los preparativos de todo el montaje. <img alt="Figura 1" src="/files/ftp_upload/52506/52506fig1highres.jpg" /> Figura 1. Organización de la ENS. La ENS contiene dos grandes plexos ganglionares. El plexo mientérico se encuentra entre el lcapas musculares ongitudinal y circulares. El plexo submucoso está situado entre la mucosa y la capa muscular circular. La ENS está exclusivamente compuesto por neuronas y glía entérica. Tractos de fibras nerviosas se conectan los ganglios. <a href="https://www.jove.com/files/ftp_upload/52506/52506fig1large.jpg" target="_blank">Por favor, haga clic aquí para ver una versión más grande de esta figura.</a> <img alt="Figura 2" src="/files/ftp_upload/52506/52506fig2highres.jpg" /> Figura 2. entérica glía en el conejillo de indias de colon responden plexo mientérico de ATP in situ. (A) Fluo-4 de fluorescencia en un ganglio mientérico (delineado por la línea de puntos) en condiciones basales. Las flechas apuntan a tractos de fibras interganglionic gruesos. (B) Después de la estimulación con 100 mmol / L de ATP, las células gliales, pero no neuronas, aumentan rápidamente Fluo-4 de fluorescencia que indica un aumento de la [Ca 2 +] <sub&gt; i. Tenga en cuenta que las células que responden son pequeñas y rodean las neuronas mucho más grandes (espacios oscuros marcados con un asterisco). (C) glía entérica responder a ATP en una forma dependiente de la dosis con 1 mmol / L provocar respuestas máximas 24. <a href="https://www.jove.com/files/ftp_upload/52506/52506fig2large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta cifra.</a> <img alt="Figura 3" src="/files/ftp_upload/52506/52506fig3highres.jpg" /> + Células Figura 3. murino S-100-GFP en el colon responden plexo mientérico a ATP in situ. (A) células gliales (verde) en un ratón de colon ganglio mientérico S-100-GFP + (esbozados por línea de trazos). Seis regiones de interés (ROI) que rodea las células gliales en los ganglios se muestran como círculos amarillos. Las flechas indican los tractos de fibras gruesas que llevan en el ganglio. Los asteriscos dubicación enote de 2 neuronas entéricas. (B) La misma muestra de ganglio Rhod-2 fluorescencia bajo condiciones basales. (C) Después de la estimulación con 100 mol / L ATP, las células gliales responden con un aumento de [Ca2 +] i como se muestra por el aumento de Rhod- 2 de fluorescencia. (D) Huellas correspondiente a cada retorno de la inversión se muestra en A-C. (E) con un promedio de respuesta (media ± SEM) de las 6 regiones de interés se muestran en D 24. <a href="https://www.jove.com/files/ftp_upload/52506/52506fig3large.jpg" target="_blank">Haga clic aquí para ver una versión más grande de esta figura.</a> <img alt="Figura 4" src="/files/ftp_upload/52506/52506fig4highres.jpg" /> La Figura 4. En las imágenes in situ de comunicación entérica-neurona-glía a. (A) Imágenes representativas (pseudocoloreada) de un experimento de imágenes de Ca 2+ en su conjunto de montajepreparación del plexo mientérico fue impugnada con el agonista del receptor neuronal P2X7 BzATP (100 m, 30 s). Tenga en cuenta que el agonista neuronal provoca un aumento en la fluorescencia Fluo4 en la neurona (A &#39;) antes de las células circundantes entéricos gliales (A &quot;). (B) Análisis del cambio en la fluorescencia con el tiempo en la glía (azul) y las neuronas (rojo ) tras la aplicación del agonista neuronal, BzATP. (C) Neuronal y respuestas gliales a BzATP en tampón normal (líneas continuas) y en tampón que contenía bajo Ca 2+ y Mg 2+ (líneas de trazos) para potenciar los receptores P2X7 neuronales 13. <a href="https://www.jove.com/files/ftp_upload/52506/52506fig4large.jpg" target="_blank">Por favor haga clic aquí para ver una versión más grande de esta figura.</a> Vídeo 1. agonista-evocó Ca 2 + respuesta en glía entérica ensitu. Este video muestra un ganglio mientérico del colon distal ratón cargado con el Ca 2 + colorante indicador, Fluo-4. El agonista de células gliales, ADP, se añade al baño cuando esté indicado. ADP provoca un aumento de Ca2 + intracelular en glía entérica como se observa por la elevación transitoria de Fluo-4 fluorescencia. <a href="https://www.jove.com/files/ftp_upload/52506/JOVE.mp4" target="_blank">Por favor, haga clic aquí para ver el vídeo.</a>

Watch this Scientific Journal Video about In Situ Ca2+ Imaging of the Enteric Nervous System at JoVE.com

In Situ Ca2+ Imaging of the Enteric Nervous System

The enteric nervous system (ENS) is a network of neurons and glia located in the gut wall that controls intestinal reflexes. This protocol describes methods for recording the activity of enteric neurons and glia in live preparations of ENS using Ca2+ imaging.

In Situ Ca 2+ Imaging del sistema nervioso entérico

Reflex behaviors of the intestine are controlled by the enteric nervous system (ENS). The ENS is an integrative network of neurons and glia in two ...

in-situ-ca2-imaging-of-the-enteric-nervous-system

Research

JoVE Journal

Neuroscience

In Situ Ca2+ Imaging of the Enteric Nervous System

17.0K vistas.  Michigan State University. The enteric nervous system (ENS) is a network of neurons and glia located in the gut wall that controls intestinal reflexes. This protocol describes methods for recording the activity of enteric neurons and glia in live preparations of ENS using Ca2+ imaging. 

Video: In Situ Ca2+ Imaging of the Enteric Nervous System

Oral Administration of Rotenone using a Gavage and Image Analysis of Alpha-synuclein Inclusions in the Enteric Nervous System

In Parkinson's disease (PD) patients, the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS) 1,2, the olfactory bulb (OB), the dorsal motor nucleus of the vagus (DMV)3, the intermediolateral nucleus of the spinal cord 4 and the substantia nigra, providing the basis for the neuropathological staging of the disease4,5. The ENS and the OB are the most exposed nervous structures and the first ones to be affected. Interestingly, PD has been related to pesticide exposure6-8. Here we show in detail two methods used in our previous study 9. In order to analyze the effects of rotenone acting locally on the ENS, we administered rotenone using a gavage to one-year old C57/BL6 mice. Rotenone is a widely used pesticide that strongly inhibits mitochondrial Complex I 10. It is highly lipophylic and poorly absorbed in the gastrointestinal tract 11. Our results showed that the administration of 5 mg/kg of rotenone did not inhibit mitochondrial Complex I activity in the muscle or the brain. Thus, suggesting that using our administration method rotenone did not cross the hepatoportal system and was acting solely on the ENS. Here we show a method to administer pesticides using a gavage and the image analysis protocol used to analyze the effects of the pesticide in alpha-synuclein accumulation in the ENS. The first part shows a method that allows intragastric administration of pesticides (rotenone) at a desired precise concentration. The second method shows a semi-automatic image analysis protocol to analyze alpha-synuclein accumulation in the ENS using an image analysis software.

Parkinson's disease has been related to the exposure to pesticides. Here we show a method to deliver pesticides using a gastric tube at the desired concentration and a method to analyze their effect in alpha-synuclein accumulation in the enteric nervous system.

La administración oral de la rotenona con una sonda y Análisis de Imágenes de la alfa-sinucleína inclusiones en el sistema nervioso entérico

In Parkinson's disease (PD) patients, the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS) 1,2, ...

Investigación

Neurociencias

Visualization of the Embryonic Nervous System in Whole-mount Drosophila Embryos

The Drosophila embryo is an attractive model system for investigating the cellular and molecular basis of neuronal development. Here we describe the procedure for the visualization of Drosophila embryonic nervous system using antibodies to neuronal proteins. Since the entire embryonic peripheral nervous and central nervous systems are well characterized at the level of individual cells (Dambly-Chaudi&egrave;re et al., 1986; Bodmer et al., 1987; Bodmer et al., 1989), any aberrations to these systems can be easily identified using antibodies to different neuronal proteins. The developing embryos are collected at certain times to ensure that the embryos are in the proper developmental stages for visualization. After collection, the outer layers of the embryo, the chorion membrane and the vitelline envelope that surrounds the embryo, are removed before fixation. Embryos are then incubated with neuronal antibodies and visualized using fluorescently labeled secondary antibodies. Embryos at stages 12-17 are visualized to access the embryonic nervous system. At stage 12 the CNS germ band starts shortening and by stage 15 the definitive pattern of the commissure has been achieved. By stage 17 the CNS contracts and the PNS is fully developed (Campos-Ortega et al. 1985). Thus changes in the pattern of the PNS and CNS can be easily observed during these developmental stages.

Visualization of the Embryonic Nervous System in Whole-mount Drosophila Embryos

We describe the procedure to prepare staged Drosophila embryos for the visualization of the embryonic nervous system during embryogenesis.

Visualización del sistema nervioso embrionario en Todo el montaje Drosophila Los embriones

The Drosophila embryo is an attractive model system for investigating the cellular and molecular basis of neuronal development. Here we describe the ...

Patch-clamp Capacitance Measurements and Ca2+ Imaging at Single Nerve Terminals in Retinal Slices

Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate retina. Two classes of retinal neurons, photoreceptors and bipolar cells, accomplish this by using ribbon-type active zones, which enable sustained and high-throughput neurotransmitter release over long time periods. ON-type mixed bipolar cell (Mb) terminals in the goldfish retina, which depolarize to light stimuli and receive mixed rod and cone photoreceptor input, are suitable for the study of ribbon-type synapses both due to their large size (~10-12 &mu;m diameter) and to their numerous lateral and reciprocal synaptic connections with amacrine cell dendrites. Direct access to Mb bipolar cell terminals in goldfish retinal slices with the patch-clamp technique allows the measurement of presynaptic Ca2+ currents, membrane capacitance changes, and reciprocal synaptic feedback inhibition mediated by GABAA and GABAC receptors expressed on the terminals. Presynaptic membrane capacitance measurements of exocytosis allow one to study the short-term plasticity of excitatory neurotransmitter release 14,15. In addition, short-term and long-term plasticity of inhibitory neurotransmitter release from amacrine cells can also be investigated by recordings of reciprocal feedback inhibition arriving at the Mb terminal 21. Over short periods of time (e.g. ~10 s), GABAergic reciprocal feedback inhibition from amacrine cells undergoes paired-pulse depression via GABA vesicle pool depletion 11. The synaptic dynamics of retinal microcircuits in the inner plexiform layer of the retina can thus be directly studied.
The brain-slice technique was introduced more than 40 years ago but is still very useful for the investigation of the electrical properties of neurons, both at the single cell soma, single dendrite or axon, and microcircuit synaptic level 19. Tissues that are too small to be glued directly onto the slicing chamber are often first embedded in agar (or placed onto a filter paper) and then sliced 20, 23, 18, 9. In this video, we employ the pre-embedding agar technique using goldfish retina. Some of the giant bipolar cell terminals in our slices of goldfish retina are axotomized (axon-cut) during the slicing procedure. This allows us to isolate single presynaptic nerve terminal inputs, because recording from axotomized terminals excludes the signals from the soma-dendritic compartment. Alternatively, one can also record from intact Mb bipolar cells, by recording from terminals attached to axons that have not been cut during the slicing procedure. Overall, use of this experimental protocol will aid in studies of retinal synaptic physiology, microcircuit functional analysis, and synaptic transmission at ribbon synapses.

Patch-clamp Capacitance Measurements and Ca2+ Imaging at Single Nerve Terminals in Retinal Slices

Here we describe a protocol for the preparation of agar-embedded retinal slices that are suitable for electrophysiology and Ca2+ imaging. This method allows one to study ribbon-type synapses in retinal microcircuits using direct patch-clamp recordings of single presynaptic nerve terminals.

Patch-clamp mediciones de capacitancia y Ca 2 + Imágenes en las terminaciones nerviosas individuales en rebanadas de retina

Visual stimuli are detected and conveyed over a wide dynamic range of light intensities and frequency changes by specialized neurons in the vertebrate ...

Multimodal Imaging of Stem Cell Implantation in the Central Nervous System of Mice

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, both in preclinical and clinical studies. However, to date results regarding functional outcome and/or tissue regeneration following stem cell transplantation are quite diverse. Generally, a clinical benefit is observed without profound understanding of the underlying mechanism(s)1. Therefore, multiple efforts have led to the development of different molecular imaging modalities to monitor stem cell grafting with the ultimate aim to accurately evaluate survival, fate and physiology of grafted stem cells and/or their micro-environment. Changes observed in one or more parameters determined by molecular imaging might be related to the observed clinical effect. In this context, our studies focus on the combined use of bioluminescence imaging (BLI), magnetic resonance imaging (MRI) and histological analysis to evaluate stem cell grafting.
BLI is commonly used to non-invasively perform cell tracking and monitor cell survival in time following transplantation2-7, based on a biochemical reaction where cells expressing the Luciferase-reporter gene are able to emit light following interaction with its substrate (e.g. D-luciferin)8, 9. MRI on the other hand is a non-invasive technique which is clinically applicable10 and can be used to precisely locate cellular grafts with very high resolution11-15, although its sensitivity highly depends on the contrast generated after cell labeling with an MRI contrast agent. Finally, post-mortem histological analysis is the method of choice to validate research results obtained with non-invasive techniques with highest resolution and sensitivity. Moreover end-point histological analysis allows us to perform detailed phenotypic analysis of grafted cells and/or the surrounding tissue, based on the use of fluorescent reporter proteins and/or direct cell labeling with specific antibodies.
In summary, we here visually demonstrate the complementarities of BLI, MRI and histology to unravel different stem cell- and/or environment-associated characteristics following stem cell grafting in the CNS of mice. As an example, bone marrow-derived stromal cells, genetically engineered to express the enhanced Green Fluorescent Protein (eGFP) and firefly Luciferase (fLuc), and labeled with blue fluorescent micron-sized iron oxide particles (MPIOs), will be grafted in the CNS of immune-competent mice and outcome will be monitored by BLI, MRI and histology (Figure 1).

This article describes an optimized sequence of events for multimodal imaging of cellular grafts in rodent brain using: (i) in vivo bioluminescence and magnetic resonance imaging, and (ii) post mortem histological analysis. Combining these imaging modalities on a single animal allows cellular graft evaluation with high resolution, sensitivity and specificity.

Imagen multimodal de implante de células madre en el sistema nervioso central de ratones

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, ...

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

In this article we describe how to individually label neurons in the embryonic CNS of Drosophila melanogaster by juxtacellular injection of the lipophilic fluorescent membrane marker DiI. This method allows the visualization of neuronal cell morphology in great detail. It is possible to label any cell in the CNS: cell bodies of target neurons are visualized under DIC optics or by expression of a fluorescent genetic marker such as GFP. After labeling, the DiI can be transformed into a permanent brown stain by photoconversion to allow visualization of cell morphology with transmitted light and DIC optics. Alternatively, the DiI-labeled cells can be observed directly with confocal microscopy, enabling genetically introduced fluorescent reporter proteins to be colocalised. The technique can be used in any animal, irrespective of genotype, making it possible to analyze mutant phenotypes at single cell resolution.

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

We present a technique for labeling single neurons in the central nervous system (CNS) of Drosophila embryos, which allows the analysis of neuronal morphology by either transmitted light or confocal microscopy.

El marcaje de células individuales en el Sistema Nervioso Central de<em&gt; Drosophila melanogaster</em

In this  article we describe how to individually label neurons in the embryonic CNS of Drosophila melanogaster by juxtacellular injection of the ...

Direct Intraventricular Delivery of Drugs to the Rodent Central Nervous System

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses specifically on antisense oligonucleotides (ASOs), though the techniques shown in the video here can also be used to deliver a plethora of other drugs to the CNS. Antisense oligonucleotides (ASOs) have the capability to knockdown sequence-specific targets 1 as well as shift isoform ratios of specific genes 2. To achieve widespread gene knockdown or splicing in the CNS of mice, the ASOs can be delivered into the brain using two separate routes of administration, both of which we demonstrate in the video.
The first uses Alzet osmotic pumps, connected to a catheter that is surgically implanted into the lateral ventricle. This allows the ASOs to be continuously infused into the CNS for a designated period of time. The second involves a single bolus injection of a high concentration of ASO into the right lateral ventricle. Both methods use the mouse cerebral ventricular system to deliver the ASO to the entire brain and spinal cord, though depending on the needs of the study, one method may be preferred over the other.

We describe a method to target drugs to the central nervous system by either implanting a catheter or performing a bolus injection into the right lateral ventricle in mice. We focus specifically on the delivery of antisense oligonucleotides. This technique is readily adaptable to other drugs and to rats.

Entrega intraventricular directa de medicamentos al roedor Sistema Nervioso Central

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses ...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing.

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing paradigms.

In vivo optogenético la estimulación del sistema nervioso central de roedores

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...

Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina

Retinal cone photoreceptors (cones) serve daylight vision and are the basis of color discrimination. They are subject to degeneration, often leading to blindness in many retinal diseases. Calcium (Ca2+), a key second messenger in photoreceptor signaling and metabolism, has been proposed to be indirectly linked with photoreceptor degeneration in various animal models. Systematically studying these aspects of cone physiology and pathophysiology has been hampered by the difficulties of electrically recording from these small cells, in particular in the mouse where the retina is dominated by rod photoreceptors. To circumvent this issue, we established a two-photon Ca2+ imaging protocol using a transgenic mouse line that expresses the genetically encoded Ca2+ biosensor TN-XL exclusively in cones and can be crossbred with mouse models for photoreceptor degeneration. The protocol described here involves preparing vertical sections (&#8220;slices&#8221;) of retinas from mice and optical imaging of light stimulus-evoked changes in cone Ca2+ level. The protocol also allows &#8220;in-slice measurement&#8221; of absolute Ca2+ concentrations; as the recordings can be followed by calibration. This protocol enables studies into functional cone properties and is expected to contribute to the understanding of cone Ca2+ signaling as well as the potential involvement of Ca2+ in photoreceptor death and retinal degeneration.

Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina

We describe a protocol to monitor Ca2+ dynamics in the axon terminals of cone photoreceptors using an ex-vivo&#160;slice preparation of the mouse retina. This protocol allows comprehensive studies of cone Ca2+ signaling in an important mammalian model system, the mouse.

Imagen Ca<sup&gt; 2 +</sup&gt; Dinámica de Terminales cono fotorreceptor axón de la retina del ratón

Retinal cone photoreceptors (cones) serve daylight vision and are the basis of color discrimination. They are subject to degeneration, often leading to ...

Transplantation of Chemogenetically Engineered Cortical Interneuron Progenitors into Early Postnatal Mouse Brains

Neuronal development is regulated by a complex combination of environmental and genetic factors. Assessing the relative contribution of each component is a complicated task, which is particularly difficult in regards to the development of &#947;-aminobutyric acid (GABA)ergic cortical interneurons (CIs). CIs are the main inhibitory neurons in the cerebral cortex, and they play key roles in neuronal networks, by regulating both the activity of individual pyramidal neurons, as well as the oscillatory behavior of neuronal ensembles. They are generated in transient embryonic structures (medial and caudal ganglionic eminences -&#160;MGE and CGE) that are very difficult to efficiently target using in utero electroporation approaches. Interneuron progenitors migrate long distances during normal embryonic development, before they integrate in the cortical circuit. This remarkable ability to disperse and integrate into a developing network can be hijacked by transplanting embryonic interneuron precursors into early post-natal host cortices. Here, we present a protocol that allows genetic modification of embryonic interneuron progenitors using focal ex vivo electroporation. These engineered interneuron precursors are then transplanted into early post-natal host cortices, where they will mature into easily identifiable CIs. This protocol allows the use of multiple genetically encoded tools, or the ability to regulate the expression of specific genes in interneuron progenitors, in order to investigate the impact of either genetic or environmental variables on the maturation and integration of CIs.

Here we present a protocol, designed to use chemogenetic tools to manipulate the activity of cortical interneuron progenitors transplanted into the cortex of early postnatal mice.

Trasplante de progenitores interneuronas corticales de ingeniería química en cerebros de ratón postnatal temprano

Neuronal development is regulated by a complex combination of environmental and genetic factors. Assessing the relative contribution of each component is ...

Intrathecal Delivery of Antisense Oligonucleotides in the Rat Central Nervous System

The blood brain barrier (BBB) is an important defense against the entrance of potentially toxic or pathogenic agents from the blood into the central nervous system (CNS). However, its existence also dramatically lowers the accessibility of systemically administered therapeutic agents to the CNS. One method to overcome this, is to inject those agents directly into the cerebrospinal fluid (CSF), thus bypassing the BBB. This can be done via implantation of a catheter for either continuous infusion using an osmotic pump, or for single bolus delivery. In this article, we describe a surgical protocol for delivery of CNS-targeting antisense oligonucleotides (ASOs) via a catheter implanted directly into the cauda equina space of the adult rat spine. As representative results, we show the efficacy of a single bolus ASO intrathecal (IT) injection via this catheterization system in knocking down the target RNA in different regions of the rat CNS. The procedure is safe, effective and does not require expensive equipment or surgical tools. The technique described here can be adapted to deliver drugs in other modalities as well.

Here, we describe a method for delivering drugs to the rat central nervous system by implanting a catheter into the lumbar intrathecal space of the spine. We focus on the delivery of antisense oligonucleotides, though this method is suitable for delivery of other therapeutic modalities as well.

Entrega intratecal de oligonucleótidos antisentido en el sistema nervioso central de Rata

The blood brain barrier (BBB) is an important defense against the entrance of potentially toxic or pathogenic agents from the blood into the central ...