Este trabajo fue parcialmente apoyado por el NIH RO1-EY019951 (AAF), Sociedad de Illinois para la Prevención de la Ceguera (JCC, AAF), los fondos de libre disposición para el Departamento de Oftalmología de la investigación para prevenir la ceguera (RPB), Nueva York y RPB Medical Student Fellowship subvención (JCC).

1. Preparación de retina <ol><li> Enucleación del ojo del ratón. Uso de un lado, abrir las tapas del ojo para que el ojo es visible. Con la otra mano, usando unas pinzas curvas (curvas mirando hacia arriba), aplique presión en los aspectos superior e inferior de la órbita hasta que sobresalga el globo. Cierre suavemente fórceps en el aspecto posterior del ojo y levantar en un movimiento continuo a enucleación del ojo. </li><li> Fijar ojo con 10% formalina tamponada neutra durante al menos 24 horas. </li><li> Lugar ojo en una solución de PBS en una placa de Petri pequeña. </li><li> Diseccionar retina cuidadosamente bajo un microscopio, teniendo cuidado de evitar la inducción de grandes lágrimas. Hacer un corte inicial en la córnea con tijeras de disección. Entonces, mientras se mantiene la zona de corte con unas pinzas rectas, utilice unas tijeras para cortar a lo largo de la frontera de la córnea y la esclerótica retirar la córnea. El uso de pinzas curvas y rectas finas, con cuidado la cáscara de la esclerótica y la coroides a la retina hacia el nervio óptico. Este paso requiere paciencia,liberar rápidamente la retina puede llevar a las lágrimas. Retirar la lente y cualquier exceso del iris y los residuos de la retina 16. </li></ol> 2. Lavados con agua <ol><li> Colocar la retina en una placa de 24 pocillos y se tapa con agua (aproximadamente 500 l, se filtra con al menos un filtro de 45 micras). </li><li> Cambie el agua cada 30 minutos-1 hora, por lo menos 4-5 veces. </li><li> Deja toda la noche en agua con agitación suave a temperatura ambiente. </li></ol> Nota: Los pasos de lavado son muy importantes ya que ayudan a separar las capas de la retina neural de los vasos sanguíneos. 3. Digestión con tripsina <ol><li> Eliminar el agua y la retina se incuban en una solución de 3% de tripsina (Difco 1:250) en tampón Tris 0,1 M (pH 7,8) a 37 ° C con agitación suave a ninguna. Tripsina digestión se completa cuando el tejido comienza a mostrar signos de desintegración (aproximadamente 1,5 horas). Nota: Evite una agitación rápidaya que esto puede dañar los vasos. </li><li> Con cuidado, pipetear cabo tripsina en un pocillo separado usando un microscopio para evitar tocar la retina. Este exceso de tripsina puede ser utilizado más tarde, cuando la manipulación de los buques bajo el microscopio, en el paso 4.3. </li></ol> 4. La separación de la vasculatura <ol><li> Añadir agua filtrada a la retina. A continuación, tratar de desprenderse de la membrana limitante interna con pinzas, con unas tijeras si es necesario. Agitar con agitación suave durante 5 min. Con cuidado, pipetear el agua bajo el microscopio para evitar dañar la retina. </li><li> Repita los lavados con agua (por 5 minutos cada uno) para ayudar a liberar a la red de vasos del tejido retinal adherente. Lavados con agua se completan cuando hay poco o ningún residuo que queda en el agua después del lavado. </li><li> Manipulación cuidadosa bajo un microscopio de disección ahora son necesarios para liberar más la red de vasos. A continuación se presentan varias técnicas útiles, que pueden utilizarse en secuencia o individually para lograr el resultado deseado basada en la preferencia técnica: <ol class="lalpha"><li> Usando una pipeta de 200, pipeta cuidadosamente agua hacia arriba y hacia abajo al lado de los barcos, que sopla del agua en los vasos, causando agitación suave. </li><li> Con 200 l pipeta pipeta la tripsina arriba y hacia abajo para ayudar a las paredes del escudo de la pipeta. Y luego, cuidadosamente pipeta toda la red de vasos hacia arriba y hacia abajo una vez para ayudar a romper el tejido no vascular. Nota: Centrado de la punta de la pipeta en el nervio óptico en lugar de los bordes de la red vascular también puede prevenir la vasculatura se pegue a la punta. </li><li> Levante suavemente vasculatura con unas pinzas finas de agua para desalojar a los componentes no vasculares. </li><li> Si los pasos anteriores no funcionan, añadir tripsina a la retina para ayudar a romper el tejido, y se incuba a 37 ° C durante varios minutos. A continuación, retire la tripsina y repita los pasos 4.1-4.3. </li></ol></li></ol> &lt;strong&gt; Nota: Asegúrese de cubrir todos los instrumentos que entren en contacto con los vasos de tripsina (por ejemplo, puntas de pipeta, pinzas). Esto ayudará a evitar la adhesión de la vasculatura para el equipo. 5. Visualización de la vasculatura <ol><li> Coloque una gota de agua sobre un portaobjetos limpio. Usando una pipeta de 200 o fórceps, transferir los vasos digeridos en el agua. Asegúrese de que el vascular plana de montaje se desarrolló. La tensión superficial del agua ayuda a desplegar la red vascular ahora diáfano. Si el tejido no se desarrolla, añada más agua y agite suavemente el portaobjetos para facilitar despliegue. </li><li> Retire el exceso de agua muy lentamente con la pipeta o con una toalla de papel. </li><li> Permita que se sequen por completo. </li><li> Teñir diapositivas a través del protocolo adecuado, ya sea con PAS / hematoxilina o H &amp; E tinción. Nota: PAS / hematoxilina es útil para identificar pared del vaso y núcleos celulares, H &amp; E es útil para demonstration de RBC también. </li><li> Deshidratar y montar (Permount medio de montaje). </li></ol>

<ol>
	<li>Kuwabara, T., Cogan, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+of+retinal+vascular+patterns.+I.+Normal+architecture.">Studies of retinal vascular patterns. I. Normal architecture.</a> Arch. Ophthalmol. 64, 904-911 (1960).</li><li>Kuwabara, T., Cogan, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+vascular+patterns.+VII.+Acellular+change.">Retinal vascular patterns. VII. Acellular change.</a> Invest. Ophthalmol. 4, 1049-1064 (1965).</li><li>Bell, W. R., Green, W. R., Goldberg, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histopathologic+and+trypsin+digestion+studies+of+the+retina+in+incontinentia+pigmenti.">Histopathologic and trypsin digestion studies of the retina in incontinentia pigmenti.</a> Ophthalmology. 115, 893-897 (2008).</li><li>Danis, R. P., Wallow, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HRP/trypsin+technique+for+studies+of+the+retinal+vasculature.">HRP/trypsin technique for studies of the retinal vasculature.</a> Invest. Ophthalmol. Vis. Sci. 27, 434-437 (1986).</li><li>Kim, S. H., Chu, Y. K., Kwon, O. W., McCune, S. A., Davidorf, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphologic+studies+of+the+retina+in+a+new+diabetic+model;+SHR/N:Mcc-cp+rat.">Morphologic studies of the retina in a new diabetic model; SHR/N:Mcc-cp rat.</a> Yonsei Med. J. 39, 453-462 (1998).</li><li>Cuthbertson, R. A., Mandel, T. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomy+of+the+mouse+retina.+Endothelial+cell-pericyte+ratio+and+capillary+distribution.">Anatomy of the mouse retina. Endothelial cell-pericyte ratio and capillary distribution.</a> Invest. Ophthalmol. Vis. Sci. 27, 1659-1664 (1986).</li><li>Laver, N. M., Robison, W. G., Pfeffer, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+procedures+for+isolating+intact+retinal+vascular+beds+from+diabetic+humans+and+animal+models.">Novel procedures for isolating intact retinal vascular beds from diabetic humans and animal models.</a> Invest. Ophthalmol. Vis. Sci. 34, 2097-2104 (1993).</li><li>Midena, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+retina+of+the+diabetic+db/db+mouse.+I.+Endothelial+cell-pericyte+ratio.">Studies on the retina of the diabetic db/db mouse. I. Endothelial cell-pericyte ratio.</a> Ophthalmic Res. 21, 106-111 (1989).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+30.">Chapter 30.</a> Diabetic Retinopathy. , (2005).</li><li>Rosenblatt, B., Benson, W. E., Yannoff, M., Duker, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+6.19+Diabetic+Retinopathy.">Chapter 6.19 Diabetic Retinopathy.</a> Ophthalmology. , (2008).</li><li>Friedenwald, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+approach+to+some+problems+of+retinal+vascular+disease.">A new approach to some problems of retinal vascular disease.</a> Am. J. Ophthalmol. 32, 487-498 (1949).</li><li>Podesta, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bax+is+increased+in+the+retina+of+diabetic+subjects+and+is+associated+with+pericyte+apoptosis+in+vivo+and+in+vitro.">Bax is increased in the retina of diabetic subjects and is associated with pericyte apoptosis in vivo and in vitro.</a> Am. J. Pathol. 156 (10), 1025-1032 (2000).</li><li>Dagher, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+of+rat+and+human+retinas+predict+a+role+for+the+polyol+pathway+in+human+diabetic+retinopathy.">Studies of rat and human retinas predict a role for the polyol pathway in human diabetic retinopathy.</a> Diabetes. 53, 2404-2411 (2004).</li><li>Puro, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinovascular+physiology+and+pathophysiology:+new+experimental+approach/new+insights.">Retinovascular physiology and pathophysiology: new experimental approach/new insights.</a> Prog. Retin. Eye Res. 31, 258-270 (2012).</li><li>Roy, S., Nasser, S., Yee, M., Graves, D. T., Roy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+long-term+siRNA+strategy+regulates+fibronectin+overexpression+and+improves+vascular+lesions+in+retinas+of+diabetic+rats.">A long-term siRNA strategy regulates fibronectin overexpression and improves vascular lesions in retinas of diabetic rats.</a> Mol. Vis. 17, 3166-3174 (2011).</li><li>Li, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diabetic+eNOS-knockout+mice+develop+accelerated+retinopathy.">Diabetic eNOS-knockout mice develop accelerated retinopathy.</a> Invest. Ophthalmol. Vis. Sci. 51, 5240-5246 (2010).</li><li>Connor, K. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantification+of+oxygen-induced+retinopathy+in+the+mouse:+a+model+of+vessel+loss,+vessel+regrowth+and+pathological+angiogenesis.">Quantification of oxygen-induced retinopathy in the mouse: a model of vessel loss, vessel regrowth and pathological angiogenesis.</a> Nature Protocols. 4, 1565-1573 (2009).</li></ol>

Los autores declaran que no tienen intereses financieros en competencia.

Digestión con tripsina es un método estándar para evaluar la vasculatura de la retina. Por desgracia, es técnicamente difícil y puede dar lugar a alta tasa de pérdida de muestra si no se realiza correctamente. Además, el procedimiento es especialmente difícil en ratones, lo cual puede limitar la aplicación de esta técnica en los modelos animales genéticos comúnmente utilizados de enfermedades de los ojos. Este documento proporciona una guía sobre cómo llevar a cabo con eficacia y coherencia del procedimien...

Visualización de la vasculatura de la retina es un enfoque extremadamente importante para diseccionar los mecanismos de diversas enfermedades oculares tales como retinopatía diabética. Esto permite evaluar las anormalidades vasculares tempranas, como microaneurismas, degeneración capilar, y la pérdida de pericitos 8,9. Hasta la fecha, se han realizado varias técnicas desarrolladas para analizar la vasculatura de la retina. La perfusión de varios tintes se ha utilizado para resaltar los vasos, pero todos han compartido las mismas limitaciones. Inyección rara vez se pone de relieve toda la vasculatura de la retina a menos dado a una alta presión, lo que corre el riesgo de romperse y dañar los vasos 1. La inmunotinción del endotelio vascular con fluoróforo marcado con T isolectina B4 (Alexa Fluor 594 conjugado; I21413; Invitrogen; dilución 1:100) y montajes planos de retina puede resaltar la arquitectura general de los vasos, pero sin visualización detallada de los capilares, la membrana basal y pericitos . Se tomó nota deFriedenwald que los barcos se pueden destacar por tinción planas montes de retina con ácido periódico de Schiff (PAS) o hematoxilina y eosina (H &amp; E) tinción 10. Sin embargo, la tinción no era específica para los vasos y pone de relieve el tejido no vascular, así, por lo que es difícil de diferenciar de los vasos. En la década de 1960, Cogan y Kuwabara desarrollaron la técnica de digestión con tripsina que hace más fácil la visualización de la vasculatura de la retina mediante la digestión de los componentes no vasculares de la retina 1. Desde ese momento, la digestión con tripsina se ha convertido en el método estándar de oro en el análisis de la vasculatura de la retina 2-5. Sin embargo, es importante señalar que se han descrito otras técnicas alternativas para aislar la vasculatura. El uso de la lisis osmótica se ha utilizado para aislar la vasculatura y permitir estudios bioquímicos del tejido 11,12, pero el procedimiento no se ha utilizado como un método principal para el estudio anatómico. El método de impresión tejido ha sidoutilizado para aislar grandes segmentos de la microvasculatura y permite la posibilidad de estudiar la arquitectura electrotónico de la vasculatura 13. En teoría, esta técnica podría utilizarse también para estudiar los cambios anatómicos, como la calidad de los vasos es alta. Sin embargo, sólo es capaz de aislar segmentos de toda la red de vasculatura. Aunque estos métodos no pueden sustituir a digestión con tripsina, es importante tener en cuenta que tienen diferentes ventajas y desventajas y son complementarias a este respecto. El método de digestión con tripsina es técnicamente difícil y es difícil de realizar consistentemente 6,7. Por otra parte, se ha observado que la digestión con tripsina es especialmente difícil en un modelo de ratón, en particular si se desea preservar la arquitectura vascular general de la retina 6,7. Los desafíos incluyen (1) sobre la digestión de la retina que causa la pérdida tanto de la vasculatura así como el tejido no vascular, (2) bajo la digestión, lo que requiereamplia disección mecánica que podría a su vez conducir a un daño de la cama buque, (3) pobre separación del tejido no vascular de los vasos principales de la tinción inespecífica. Varios manuscritos han destacado estos desafíos, pero ninguno ha proporcionado un protocolo detallado y consistente para superarlos 14,15. Este manuscrito introducirá una metodología paso a paso que detalla la técnica para realizar la digestión con tripsina en ratón y rata retinas con consejos específicos sobre el manejo de los pasos particularmente difíciles. Una visión general esquemática se muestra en la Figura 1.

<table border="1">
	<tbody>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>REAGENTS</td>
		</tr>
		<tr>
			<td>10% neutral buffered formalin</td>
			<td>Fischer Scientific</td>
			<td>SF100-4</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Trypsin (1:250)</td>
			<td>Amresco</td>
			<td>0458-50G</td>
			<td>Make 3% trypsin in 0.1 M Tris</td>
		</tr>
		<tr>
			<td>TRIZMA base</td>
			<td>Sigma</td>
			<td>T1503-1KG</td>
			<td>Create 0.1 M Tris Buffer (pH 7.8 @ 37 &deg;C)</td>
		</tr>
		<tr>
			<td>TRIZMA</td>
			<td>Sigma</td>
			<td>T3253-500G</td>
		</tr>
		<tr>
			<td>Steritop sterile vacuum bottle</td>
			<td>Millipore</td>
			<td>SCGPS05RE</td>
			<td>Create filtered water</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>EQUIPMENT</td>
		</tr>
		<tr>
			<td>Dissecting microscope</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Any microscope that allows good visualization of the retina is adequate. (10x is sufficient with working distance of 24 mm)</td>
		</tr>
		<tr>
			<td>Straight scissors</td>
			<td>Fine Science Tools</td>
			<td>15024-10</td>
			<td>Cutting edge: 8 mm; Tip diameter: 0.2 mm; 10 cm</td>
		</tr>
		<tr>
			<td>Straight Forceps (Inox)</td>
			<td>Dumont #5</td>
			<td>11252-20</td>
			<td>Biologie tip; 0.05 x 0.02 mm; 11 cm</td>
		</tr>
		<tr>
			<td>Curved Forcepts (Dumostar)</td>
			<td>Dumont #7</td>
			<td>11297-10</td>
			<td>Biologie tip; 0.07 x 0.04 mm; 11.5 cm</td>
		</tr>
		<tr>
			<td>Dubnoff Metabolic Shaker Incubator</td>
			<td>Precision Scientific</td>
			<td>BDG59442</td>
			<td>Shaker optional</td>
		</tr>
		<tr>
			<td>24-well dish</td>
			<td>Falcon</td>
			<td>353047</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Microscope Slides</td>
			<td>VWR</td>
			<td>82027-132</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

trypsin digest protocol to analyze the retinal vasculature of a mouse model

Digestión con tripsina es el método estándar de oro para analizar la vasculatura de la retina 1-5. Se permite la visualización de la totalidad de la red de vasos complejas tridimensionales retina y capilares sanguíneos mediante la creación de un plano de montaje en dos dimensiones de los canales vasculares interconectados después de la digestión de los componentes no-vasculares de la retina. Esto permite estudiar varios cambios patológicos vasculares, tales como microaneurismas, degeneración capilar, y anormal endoteliales a las relaciones de pericitos. Sin embargo, el método es técnicamente difícil, especialmente en los ratones, que se han convertido en el modelo animal más ampliamente disponible para estudiar la retina debido a la facilidad de manipulaciones genéticas 6,7. En el ojo del ratón, que es particularmente difícil de eliminar por completo los componentes no vasculares, mientras que el mantenimiento de la arquitectura general de los vasos sanguíneos de la retina. Hasta la fecha, hay una escasez de literatura que describe la técnica de digestión con tripsina en detalle in el ratón. Este manuscrito ofrece una metodología detallada de la digestión con tripsina en la retina del ratón, paso a paso, mientras que también proporciona consejos para la solución de problemas difíciles pasos.

El producto final de un procedimiento exitoso es un montaje plana de toda la red de la vasculatura de la retina del ratón, con la arquitectura mantiene, se tiñeron con cualquiera de PAS / hematoxilina o H &amp; E, como se muestra en las Figuras 2-4. Claro diferenciación de las células endoteliales y los pericitos se puede ver como se muestra en la Figura 3. En la retina, los núcleos de las células endoteliales son oval o alargada y situada completamente dentro de la pared del vaso...

Watch this Scientific Journal Video about Trypsin Digest Protocol to Analyze the Retinal Vasculature of a Mouse Model at JoVE.com

Trypsin Digest Protocol to Analyze the Retinal Vasculature of a Mouse Model

Digestión con tripsina es uno de los métodos más comúnmente utilizados para analizar vasculatura de la retina. Este manuscrito describe el método en detalle, incluyendo alteraciones clave para optimizar la técnica y eliminar el tejido no vascular, mientras que la preservación de la arquitectura general de los vasos.

Tripsina Protocolo Resumen Para analizar la vasculatura de la retina de un modelo de ratón

Trypsin digest is the gold standard method to analyze the retinal vasculature 1-5. It allows visualization of the entire network of complex ...

trypsin-digest-protocol-to-analyze-retinal-vasculature-mouse

Research

JoVE Journal

Neuroscience

18.2K vistas.  Northwestern University Feinberg School of Medicine. Digestión con tripsina es uno de los métodos más comúnmente utilizados para analizar vasculatura de la retina. Este manuscrito describe el método en detalle, incluyendo alteraciones clave para optimizar la técnica y eliminar el tejido no vascular, mientras que la preservación de la arquitectura general de los vasos.

Video: Trypsin Digest Protocol to Analyze the Retinal Vasculature of a Mouse Model

Patch Clamp Recordings from Mouse Retinal Neurons in a Dark-adapted Slice Preparation

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of intracellular events that lead to closure of cyclic-nucleotide-gated channels in the cell membrane. The resulting change in membrane potential leads in turn to reductions in the amount of neurotransmitter release from both rod and cone synaptic terminals. To measure how the light-evoked change in photoreceptor membrane potential leads to downstream activity in the retina, scientists have made electrophysiological recordings from retinal slice preparations for decades1,2. In the past these slices have been cut manually with a razor blade on retinal tissue that is attached to filter paper; in recent years another method of slicing has been developed whereby retinal tissue is embedded in low gelling temperature agar and sliced in cool solution with a vibrating microtome3,4. This preparation produces retinal slices with less surface damage and very robust light-evoked responses. Here we document how this procedure can be done under infrared light to avoid bleaching the visual pigment.

Here we describe a procedure for generating dark-adapted slices of the mouse retina for electrophysiological recordings.

Grabaciones de patch clamp de neuronas de ratón de retina en una rebanada preparación adaptada a la oscuridad

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of ...

Investigación

Neurociencias

Dissection of a Mouse Eye for a Whole Mount of the Retinal Pigment Epithelium

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and cones). The RPE is a monolayer of pigmented cuboidal cells and associates closely with the neural retina just above it. This association makes the RPE of great interest to researchers studying retinal diseases. The RPE is also the site of an in vivo assay of homology-directed DNA repair, the pun assay. The mouse eye is particularly difficult to dissect due to its small size (about 3.5mm in diameter) and its spherical shape. This article demonstrates in detail a procedure for dissection of the eye resulting in a whole mount of the RPE. In this procedure, we show how to work with, rather than against, the spherical structure of the eye. Briefly, the connective tissue, muscle, and optic nerve are removed from the back of the eye. Then, the cornea and lens are removed. Next, strategic cuts are made that result in significant flattening of the remaining tissue. Finally, the neural retina is gently lifted off, revealing an intact RPE, which is still attached to the underlying choroid and sclera. This whole mount can be used to perform the pun assay or for immunohistochemistry or immunofluorescent assessment of the RPE tissue.

A formal demonstration of the dissection of a mouse eye, resulting in a whole mount of the retinal pigment epithelium.

Disección de un ojo del ratón de un monte entero del epitelio pigmentario de la retina

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and ...

An Optic Nerve Crush Injury Murine Model to Study Retinal Ganglion Cell Survival

Injury to the optic nerve can lead to axonal degeneration, followed by a gradual death of retinal ganglion cells (RGCs), which results in irreversible vision loss. Examples of such diseases in human include traumatic optic neuropathy and optic nerve degeneration in glaucoma. It is characterized by typical changes in the optic nerve head, progressive optic nerve degeneration, and loss of retinal ganglion cells, if uncontrolled, leading to vision loss and blindness.
The optic nerve crush (ONC) injury mouse model is an important experimental disease model for traumatic optic neuropathy, glaucoma, etc. In this model, the crush injury to the optic nerve leads to gradual retinal ganglion cells apoptosis. This disease model can be used to study the general processes and mechanisms of neuronal death and survival, which is essential for the development of therapeutic measures. In addition, pharmacological and molecular approaches can be used in this model to identify and test potential therapeutic reagents to treat different types of optic neuropathy.
Here, we provide a step by step demonstration of (I) Baseline retrograde labeling of retinal ganglion cells (RGCs) at day 1, (II) Optic nerve crush injury at day 4, (III) Harvest the retinae and analyze RGC survival at day 11, and (IV) Representative result.

This protocol shows how to retrogradely label retinal ganglion cells, and how to subsequently make an optic nerve crush injury in order to analyze retinal ganglion cell survival and apoptosis. It is an experimental disease model for different types of optic neuropathy, including glaucoma.

Un aplastamiento del nervio óptico Lesiones modelo murino para estudiar la supervivencia de células ganglionares retinianas

Injury to the optic nerve can lead to axonal degeneration, followed by a gradual death of retinal ganglion cells (RGCs), which results in irreversible ...

Morphometric Analyses of Retinal Sections

Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the retinal ganglion cell layer (RGCL) in rat models with N-methyl-D-aspartate (NMDA)&#x2013;induced excitotoxicity1, retinal ischemia-reperfusion injury2 and glaucoma3. Reduction of INL and inner plexiform layer (IPL) thicknesses were reversed with citicoline treatment in rats' eyes subjected to kainic acid-mediated glutamate excitotoxicity4. Alteration of RGC density and soma sizes were observed with different drug treatments in eyes with elevated intraocular pressure3,5,6. Therefore, having objective methods of analyzing the retinal morphometries may be of great significance in evaluating retinal pathologies and the effectiveness of therapeutic strategies.
The retinal structure is multi-layers and several different kinds of neurons exist in the retina. The morphometric parameters of retina such as cell number, cell size and thickness of different layers are more complex than the cell culture system. Early on, these parameters can be detected using other commercial imaging software. The values are normally of relative value, and changing to the precise value may need further accurate calculation. Also, the tracing of the cell size and morphology may not be accurate and sensitive enough for statistic analysis, especially in the chronic glaucoma model. The measurements used in this protocol provided a more precise and easy way. And the absolute length of the line and size of the cell can be reported directly and easy to be copied to other files. For example, we traced the margin of the inner and outer most nuclei in the INL and formed a line then using the software to draw a 90 degree angle to measure the thickness. While without the help of the software, the line maybe oblique and the changing of retinal thickness may not be repeatable among individual observers. In addition, the number and density of RGCs can also be quantified. This protocol successfully decreases the variability in quantitating features of the retina, increases the sensitivity in detecting minimal changes.
 	This video will demonstrate three types of morphometric analyses of the retinal sections. They include measuring the INL thickness, quantifying the number of RGCs and measuring the sizes of RGCs in absolute value. These three analyses are carried out with Stereo Investigator (MBF Bioscience &mdash; MicroBrightField, Inc.). The technique can offer a simple but scientific platform for morphometric analyses.

This video demonstrates three types of morphometric analyses of the retina, which include measuring the inner nuclear layer thickness, quantifying the number of retinal ganglion cells (RGCs) and measuring the sizes of RGCs. The technique can offer a simple but scientific platform for morphometric analyses.

Los análisis morfométricos de las Secciones de retina

Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the ...

A Visual Description of the Dissection of the Cerebral Surface Vasculature and Associated Meninges and the Choroid Plexus from Rat Brain

This video presentation was created to show a method of harvesting the two most important highly vascular structures, not residing within the brain proper, that support forebrain function. They are the cerebral surface (superficial) vasculature along with associated meninges (MAV) and the choroid plexus which are necessary for cerebral blood flow and cerebrospinal fluid (CSF) homeostasis. The tissue harvested is suitable for biochemical and physiological analysis, and the MAV has been shown to be sensitive to damage produced by amphetamine and hyperthermia 1,2. As well, the major and minor cerebral vasculatures harvested in MAV are of potentially high interest when investigating concussive types of head trauma. The MAV dissected in this presentation consists of the pial and some of the arachnoid membrane (less dura) of the meninges and the major and minor cerebral surface vasculature. The choroid plexus dissected is the structure that resides in the lateral ventricles as described by Oldfield and McKinley3,4,5,6. The methods used for harvesting these two tissues also facilitate the harvesting of regional cortical tissue devoid of meninges and larger cerebral surface vasculature, and is compatible with harvesting other brain tissues such as striatum, hypothalamus, hippocampus, etc. The dissection of the two tissues takes from 5 to 10 min total. The gene expression levels for the dissected MAV and choroid plexus, as shown and described in this presentation can be found at GSE23093 (MAV) and GSE29733 (choroid plexus) at the NCBI GEO repository. This data has been, and is being, used to help further understand the functioning of the MAV and choroid plexus and how neurotoxic events such as severe hyperthermia and AMPH adversely affect their function.

This video presentation shows a method of harvesting the two most important highly vascular structures that support forebrain function. They are the cerebral surface (superficial) vasculature along with associated meninges (MAV) and the choroid plexus which are necessary for cerebral blood flow and cerebrospinal fluid (CSF) homeostasis.

Una descripción visual de la disección de la vasculatura cerebral superficial y las meninges asociada y el plexo coroideo del cerebro de rata

This video presentation was created to show a method of harvesting the two most important highly vascular structures, not residing within the brain ...

Implementing Dynamic Clamp with Synaptic and Artificial Conductances in Mouse Retinal Ganglion Cells

Ganglion cells are the output neurons of the retina and their activity reflects the integration of multiple synaptic inputs arising from specific neural circuits. Patch clamp techniques, in voltage clamp and current clamp configurations, are commonly used to study the physiological properties of neurons and to characterize their synaptic inputs. Although the application of these techniques is highly informative, they pose various limitations. For example, it is difficult to quantify how the precise interactions of excitatory and inhibitory inputs determine response output. To address this issue, we used a modified current clamp technique, dynamic clamp, also called conductance clamp 1, 2, 3 and examined the impact of excitatory and inhibitory synaptic inputs on neuronal excitability. This technique requires the injection of current into the cell and is dependent on the real-time feedback of its membrane potential at that time. The injected current is calculated from predetermined excitatory and inhibitory synaptic conductances, their reversal potentials and the cell's instantaneous membrane potential. Details on the experimental procedures, patch clamping cells to achieve a whole-cell configuration and employment of the dynamic clamp technique are illustrated in this video article. Here, we show the responses of mouse retinal ganglion cells to various conductance waveforms obtained from physiological experiments in control conditions or in the presence of drugs. Furthermore, we show the use of artificial excitatory and inhibitory conductances generated using alpha functions to investigate the responses of the cells.

This video article illustrates the set-up, the procedures to patch cell bodies and how to implement dynamic clamp recordings from ganglion cells in whole-mount mouse retinae. This technique allows the investigation of the precise contribution of excitatory and inhibitory synaptic inputs, and their relative magnitude and timing to neuronal spiking.

Implementar Clamp dinámico con conductancias sinápticas y artificiales en células de ratón ganglionares retinianas

Ganglion cells are the output neurons of the  retina and their activity reflects the integration of multiple synaptic inputs  arising from specific neural ...

Video Imaging and Spatiotemporal Maps to Analyze Gastrointestinal Motility in Mice

The enteric nervous system (ENS) plays an important role in regulating gastrointestinal (GI) motility and can function independently of the central nervous system. Changes in ENS function are a major cause of GI symptoms and disease and may contribute to GI symptoms reported in neuropsychiatric disorders including autism. It is well established that isolated colon segments generate spontaneous, rhythmic contractions known as Colonic Migrating Motor Complexes (CMMCs). A procedure to analyze the enteric neural regulation of CMMCs in ex vivo preparations of mouse colon is described. The colon is dissected from the animal and flushed to remove fecal content prior to being cannulated in an organ bath. Data is acquired via a video camera positioned above the organ bath and converted to high-resolution spatiotemporal maps via an in-house software package. Using this technique, baseline contractile patterns and pharmacological effects on ENS function in colon segments can be compared over 3-4 hr. In addition, propagation length and speed of CMMCs can be recorded as well as changes in gut diameter and contraction frequency. This technique is useful for characterizing gastrointestinal motility patterns in transgenic mouse models (and in other species including rat and guinea pig). In this way, pharmacologically induced changes in CMMCs are recorded in wild type mice and in the Neuroligin-3R451C mouse model of autism. Furthermore, this technique can be applied to other regions of the GI tract including the duodenum, jejunum and ileum and at different developmental ages in mice.

This article describes a video imaging technique and high-resolution spatiotemporal mapping to identify changes in the neural regulation of colonic motility in adult mice. Subtle effects on gastrointestinal (GI) function can be detected using this approach in isolated tissue preparations to advance our understanding of GI disease.

Imágenes de vídeo y mapas espacio-temporales para Analizar la motilidad gastrointestinal en ratones

The enteric nervous system (ENS) plays an important role in regulating gastrointestinal (GI) motility and can function independently of the central ...

Protocol for Isolating the Mouse Circle of Willis

The cerebral arterial circle (circulus arteriosus cerebri) or circle of Willis (CoW) is a circulatory anastomosis surrounding the optic chiasma and hypothalamus that supplies blood to the brain and surrounding structures. It has been implicated in several cerebrovascular disorders, including cerebral amyloid angiopathy (CAA)-associated vasculopathies, intracranial atherosclerosis and intracranial aneurysms. Studies of the molecular mechanisms underlying these diseases for the identification of novel drug targets for their prevention require animal models. Some of these models may be transgenic, whereas others will involve isolation of the cerebro-vasculature, including the CoW.The method described here is suitable for CoW isolation in any mouse lineage and has considerable potential for screening (expression of genes, protein production, posttranslational protein modifications, secretome analysis, etc.) studies on the large vessels of the mouse cerebro-vasculature. It can also be used for ex vivo studies, by adapting the organ bath system developed for isolated mouse olfactory arteries.

We describe here a reproducible protocol for isolating the mouse circle of Willis.

Protocolo para el aislamiento del Círculo de Willis Ratón

The cerebral arterial circle (circulus arteriosus cerebri) or circle of Willis (CoW) is a circulatory anastomosis surrounding the optic chiasma and ...

Preparation of Mouse Retinal Cryo-sections for Immunohistochemistry

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for determining the mechanisms underlying retinal diseases. Maintaining structural integrity throughout the tissue preparation is vital for obtaining reproducible retinal IHC data but can be challenging due to the fragility and complexity of retinal cytoarchitecture. Strong fixatives like 10% formalin or Bouin's solution optimally preserve the retinal structure, they often impede IHC analysis by enhancing the background fluorescence and/or diminishing antibody-epitope interactions, a process known as epitope masking. Milder fixatives, on the other hand, like 4% paraformaldehyde, reduces background fluorescence and epitope-masking, meticulous dissection techniques must be utilized to preserve the retinal structure. In this article, we present a comprehensive method to prepare mouse ocular posterior cups for IHC that is sufficient to preserve most antibody-epitope interactions without loss of retinal structural integrity. We include representative IHC with antibodies to various retinal cell type markers to illustrate tissue preservation and orientation under optimal and sub-optimal conditions. Our goal is to optimize IHC studies of the retina by providing a complete protocol from ocular posterior cup dissection to IHC.

This report describes comprehensive methods for preparing frozen mouse retina sections for immunohistochemistry (IHC). Methods described include dissection of the ocular posterior cup, paraformaldehyde fixation, embedding in Optimal Cutting Temperature (OCT) media and tissue orientation, sectioning and immunostaining.

Preparación de criosecciones retinianas de ratón para inmunohistoquímica

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for ...

Optimization of the Retinal Vein Occlusion Mouse Model to Limit Variability

Mouse models of retinal vein occlusion (RVO) are often used in ophthalmology to study hypoxic-ischemic injury in the neural retina. In this report, a detailed method pointing out critical steps is provided with recommendations for optimization to achieve consistently successful occlusion rates across different genetically modified mouse strains. The RVO mouse model consists primarily of the intravenous administration of a photosensitizer dye followed by laser photocoagulation using a retinal imaging microscope attached to an ophthalmic guided laser. Three variables were identified as determinants of occlusion consistency. By adjusting the wait time after rose bengal administration and balancing the baseline and experimental laser output, the variability across experiments can be limited and a higher success rate of occlusions achieved. This method can be used to study retinal diseases that are characterized by retinal edema and hypoxic-ischemic injury. Additionally, as this model induces vascular injury, it can also be applied to study the neurovasculature, neuronal death, and inflammation.

Here, we describe an optimized protocol for retinal vein occlusion using rose bengal and a laser-guided retinal imaging microscope system with recommendations to maximize its reproducibility in genetically modified strains.

Optimización del modelo de ratón de oclusión de venas retinianas para limitar la variabilidad

Mouse models of retinal vein occlusion (RVO) are often used in ophthalmology to study hypoxic-ischemic injury in the neural retina. In this report, a ...