Name: a novel model of mild traumatic brain injury for juvenile rats
Uploaded: 2014-12-08T13:00:00.000+00:00
Duration: 7 min 36 s
Description: Watch this Scientific Journal Video about A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats at JoVE.com

The authors would like to thank Irene Ma, Rose Tobais, and Jong Rho for their technical assistance. Funding was provided to MJE by the Department of Pediatrics at the University of Calgary, the Alberta Children&#8217;s Hospital Foundation (ACHF) and the Alberta Children&#8217;s Hospital Research Institute (ACHRI). The Postdoctoral fellowship for RM was provided by ACHF.

NOTA: Todos los experimentos se llevaron a cabo de acuerdo con el Consejo Canadiense de Cuidado de Animales y fueron aprobados por la Universidad de Calgary, Comité de Ética de los Animales. 1. Cría y Preparación de los animales <ol><li> Ordene ratas embarazadas de proveedores de animales de laboratorio estándar o cachorros de razas en la casa de acuerdo con los protocolos de reproducción estándar. </li><li> Casa todos los animales con acceso ad libitum a la comida y el agua, en una rata habitación vivienda temperatura controlada (21 ° C), que se mantiene en una luz 12:12 h: oscuridad ciclo. </li><li> Cuando las crías alcanzan postnatal día 21 (P21), destetar las crías de sus madres y casa en grupos del mismo sexo de 3 o 4. </li></ol> 2. Establecimiento de leve lesión cerebral traumática (LCTL) Aparato <ol><li> Antes de iniciarse el procedimiento, los pesos de molino a la masa deseado (por ejemplo, 150 g). Fije seguramente un asa de metal en el extremo superior del peso permitiendo a la línea de pesca a ser fijo al peso. </li><li> Puntuación papel de aluminio con una cuchilla afilada. Asegúrese de que el papel de aluminio marcado soporta el peso corporal de la rata, pero no va a interferir con la aceleración de la rata después de impacto de la cabeza con el peso. </li><li> Tape la lámina de estaño marcado a la etapa en forma de U hecho de plástico transparente (38 x 27 x 27 cm 3) que contiene una esponja de recogida (38 x 25 x 15 cm 3) (Figura 1), de modo que es tensa. </li><li> Coloque la etapa de plástico en forma de U en la posición correcta debajo del tubo de guía hecha de plástico transparente. </li><li> Mantenga el tubo de guía de plástico (2,2 cm de diámetro x 1,5 m) en su lugar con un soporte de abrazadera y posicionar el tubo de guía de manera que es 3,5 cm por encima de la lámina de estaño marcado. </li><li> Fije la línea de pesca a través del bucle de metal para el peso asegurando que la parte inferior de el peso cuelgue libremente 2,5 cm por encima de la lámina de estaño marcado. </li><li> Sujete con firmeza la línea de pesca en el soporte de sujeción. NOTA: Anclaje a red el peso de la almejap soporte a una altura de 2,5 cm por encima del papel de aluminio impide re-hits, mientras que la rata está cayendo por el impacto de la esponja colección). </li><li> Tire el peso hacia arriba a través del tubo guía de plástico con la línea de pesca y mantenerlo en su lugar con un pin de llave allen de 1,0 m. </li></ol> 3. Inducción de LCTL <ol><li> Cuando las ratas llegan P30 jaulas Colócate en la sala de procedimiento. </li><li> Coloque ratas en una cámara de isoflurano y ligeramente anestesiar la rata hasta que no responde a una pata o la cola pellizco. </li><li> Coloque rápidamente la rata pecho abajo en el papel de aluminio anotado con su cabeza directamente en la trayectoria de la caída de peso. Véase la Figura 2. Si la rata comienza a moverse o despertar antes de que pueda ser colocado en la hoja de la lata marcado, volver a la cámara de isoflurano hasta que no responden a una pata o la cola pellizco y comenzar de nuevo. </li><li> Tire del pasador de llave Allen, permitiendo que el peso caiga verticalmente a través del tubo de guía de plástico y golpear la rata en la cabeza. The rata se someterá a una rápida rotación y tierra 180 ° en la posición supina. </li><li> Retirar inmediatamente la rata de la esponja recogida y aplicar lidocaína tópica a la cabeza de la rata con un aplicador de punta de algodón. </li><li> Coloque la rata en la posición supina en una jaula limpia que se calienta mediante el establecimiento de que sobre una almohadilla de calefacción disponible comercialmente. </li><li> Con un cronómetro o temporizador digital adquirir el &quot;time-to-derecha&quot;. Tiempo a derecha es el tiempo empleado por la rata de despertar de la anestesia y la vuelta de la posición supina a la posición prona o comience a caminar. </li><li> Volver a la rata a su casa-jaula después de que se ha recuperado el comportamiento normal (asearse, caminar, explorar, etc.). </li><li> Repita los pasos 3.2 a 3.8 para cada rata adicional que requiere una LCTL. </li><li> Repita el procedimiento en la misma rata en múltiples puntos de tiempo para experimentos repetitivos LCTL. </li></ol> 4. Inducción de la Lesión Sham <ol><li> Ligeramente anesthetize la rata con isoflurano hasta que no responde a una pata o la cola pellizco. </li><li> Coloque rápidamente la rata pecho abajo en el papel de aluminio anotado con su cabeza directamente en la trayectoria de la caída de peso. </li><li> Retire la rata de la hoja de la lata sin tira de la pata llave allen del tubo guía de plástico y aplicar lidocaína tópica a la cabeza de la rata con un aplicador con punta de algodón. </li><li> Coloque la rata en la posición supina en una jaula limpia que se calienta mediante el establecimiento de que sobre una almohadilla de calefacción disponible comercialmente. </li><li> Use un cronómetro o temporizador digital para adquirir el &quot;time-to-derecha&quot;. </li><li> Volver a la rata a su casa-jaula después de que se ha recuperado el comportamiento normal (asearse, caminar, explorar, etc.). </li></ol> 5. Verificación de LCTL con la prueba de marcha de la viga 8 <ol><li> 24 horas después de la inducción de la LCTL o animales retorno lesión simulada a la sala de procedimiento. </li><li> Transferir las ratas a una explotación jaula limpiay colocar el hogar de jaula de la rata en el extremo más estrecho de los 165 cm de haz tal que la parte abierta de la casa de jaula enfrenta el extremo más estrecho del haz cónico. NOTA: El haz cónico es de 165 cm de largo. La plataforma del centro de la viga tiene una anchura de 6 cm en el extremo ancho y 1,75 cm en la parte más estrecha. La viga central tiene repisas (2 cm de ancho y 2 cm por debajo de la viga central) que proporcionan la seguridad cuando se resbala de la rata. Coloque el acolchado de espuma debajo de la viga de reducir el riesgo de lesiones en las ratas que pueden caer fuera de la viga durante la prueba. </li><li> Colocar una cámara de vídeo en el extremo ancho de la viga cónica y la posición / zoom de la cámara de vídeo para garantizar que el investigador viendo el vídeo puede ver claramente los movimientos de la rata para toda la longitud de la viga cónica. </li><li> Coloque la rata en el extremo ancho del haz cónico y animarla a caminar a través de la viga a su casa-jaula. Una vez que la rata cruza el haz cónico, deje la rata en su casa-jaula durante al menos 60 segundos para reinForce la ubicación de destino. Esto es Trial # 1 y no se incluye en el análisis. </li><li> Encienda la cámara de vídeo y permite la rata para completar la tarea haz de caminar 4 veces más (manteniendo los períodos de refuerzo 60 seg en la jaula de alojamiento). Una vez que la rata ha completado todos los ensayos, volver a la rata a su casa-jaula. </li><li> Para anotar, registrar el número de la pierna-pie se desliza traseras que se producen y el tiempo / duración de cruzar la viga, para cada ensayo individual. Utilizar estos datos para calcular el número medio de la pierna-pie resbalones y traseras tiempo para cruzar el haz para cada rata. </li></ol>

<ol>
	<li>DeWitt, D., Perez-Polo, R., Hulsebosch, C., Dash, P., Robertson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Challenges+in+the+development+of+rodent+models+of+mild+traumatic+brain+injury.">Challenges in the development of rodent models of mild traumatic brain injury.</a> Journal of Neurotrauma. 30, 688-701 (2013).</li><li>Xiong, Y., Mahmood, A., Chopp, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+traumatic+brain+injury.">Animal models of traumatic brain injury.</a> Nature Reviews Neuroscience. 14, 128-142 (2013).</li><li>Zhang, Z., Lerner, S., Kobiessy, F., Hayes, R., Wang, K., Yan, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systems+biology+and+the+anostic+approach+to+drug+discovery+and+development+to+treat+traumatic+brain+injury.">Systems biology and the anostic approach to drug discovery and development to treat traumatic brain injury.</a> Systems Biology in Drug Discovery and Development: Methods and Protocols, Methods in Molecular Biology. , .</li><li>Viano, D., Casson, I., Pellmen, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concussion+in+profession+football:+Biomechanics+of+the+struck+player+-+Part+14.">Concussion in profession football: Biomechanics of the struck player - Part 14.</a> Neurosurgery. 61, 313-327 (2007).</li><li>Marmarou, A., 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=A+new+model+of+diffuse+brain+injury+in+rats:+Part+1+-+Pathophysiology+and+biomechanics.">A new model of diffuse brain injury in rats: Part 1 - Pathophysiology and biomechanics.</a> Journal of Neurosurgery. 80, 291-300 (1994).</li><li>Mychasiuk, R., Farran, A., Esser, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+an+experimental+rodent+model+of+pediatric+mild+traumatic+brain+injury.">Assessment of an experimental rodent model of pediatric mild traumatic brain injury.</a> Journal of Neurotrauma. 31 (8), (2014).</li><li>Kane, 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=A+mouse+model+of+human+repetitive+mild+traumatic+brain+injury.">A mouse model of human repetitive mild traumatic brain injury.</a> Journal of Neuroscience Methods. 203, 41-49 (2012).</li><li>Schallert, T., Woodlee, M., Fleming, S., Krieglstein, J., Klumpp, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disentangling+multiple+types+of+recovery+from+brain+injury.">Disentangling multiple types of recovery from brain injury.</a> Pharmacology of Cerebral Ischemia. , (2002).</li><li>Mychasiuk, R., Hehar, H., Farran, A., Esser, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mean+Girls:+Sex+differences+in+the+effects+of+mild+traumatic+brain+injury+on+the+social+dynamics+of+juvenile+rat+play+behaviour.">Mean Girls: Sex differences in the effects of mild traumatic brain injury on the social dynamics of juvenile rat play behaviour.</a> Behavioural Brain Research. 259, (2014).</li><li>Centers for Disease Control and Prevention. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Report to congress on mild traumatic brain injury in the United States: Steps to prevent a serious public health problem. , 1-47 (2003).</li></ol>

No competing financial interests exist.

Reliable modelling systems are needed to effectively cultivate basic science research that has significant translational validity. In response to rising occurrences and popular media, the investigation of mTBI and concussion has become a priority in many disciplines. However, despite increased research, there have been only incremental improvements in therapeutic strategies and treatment options 3. This lack of progress may be partially due to a discrepancy between the modeling systems employed and actual injury etiology. The majority of studies utilized rodent models that failed to reproduce the important biomechanical forces and appropriate post-injury symptomology. The current human definition of mTBI specifies that the injury results from acceleration and deceleration forces associated with a blunt trauma 10. The modified weight drop technique described here is therefore an ideal model for the study of mTBI and concussion because it uses a glancing impact to cause rapid rotational acceleration and deceleration to the head of an unrestrained animal, mimicking the biomechanical forces identified in sports-related injuries and automobile accidents. In addition, this model is easily adapted to examine repetitive mTBI, a phenomena that is emerging as a serious medical and socioeconomic issue. Studies indicate that rodents may be exposed to a series of 10 distinct mTBIs with minimal mortality 7. Finally, the method is inexpensive and can be carried out rapidly, allowing for high-throughput examination of a many therapeutic compounds and treatment regiments. 
Just as with any procedural technique, certain aspects of the protocol are particularly important to the generation of reliable results. First, the tin foil needs to be scored effectively. If the tin foil is not properly scored, the force imparted by the weight during the glancing impact will not be enough to propel the juvenile rat through the tin foil onto the collection sponge. In these situations, the rat will remain in the starting position (chest down on the tin foil) and the mTBI will result from the blunt trauma from the weight impacting the stationary head, not the rotational acceleration and deceleration desired. Second, during the induction of the mTBI and the sham injury, the level of anesthetic applied to each rat should be consistent. Owing to the fact that time-to-right is used as marker of mTBI, the researcher should try to ensure that animals receiving a mTBI and animals receiving a sham injury are exposed to similar levels of anesthetic. A major advantage to this technique over many other TBI procedures is the low level and duration of anesthesiology. However, the juvenile rat needs to be non-responsive to a toe or tail pinch to ensure they do not wake-up on the stage before the injury is induced. Finally, in order to maintain a consistent injury etiology, the positioning of the rat&#8217;s head is particularly important. Ideally the weight should impact the center of the dorsal surface of the head. Caution should be taken to avoid positioning the path of the weight too near the caudal/posterior portion of the head, as impacting the brainstem and cerebellum is associated with increased mortality and seizure activity. 
Based upon the biomechanical pathophysiology of injury induction and the behavioural outcomes examined, the modified weight-drop technique appears to be a reliable model for the investigation of paediatric mTBI and concussion. Although preliminary studies of this novel model have assessed some basic molecular and structural changes 7 future studies will be needed to ascertain how the brain responds to a mTBI with this injury etiology. An in-depth analysis of the neuroanatomical and biological changes that occur at the cellular and epigenetic level would increase model validity and translational applicability. In addition to stimulating the generation of targeted pharmacological therapies, understanding the pathophysiological changes that occur in the brain in response to mTBI and concussion would also direct the research related to clinical biomarkers that have the ability to predict outcomes following injury.

Aunque hay muchos métodos ampliamente utilizados para la generación de moderada a severa lesión cerebral traumática (TBI), muy pocos se han desarrollado técnicas para inducir leve, cerrado heridas en la cabeza en los roedores. Debido al hecho de que la lesión cerebral traumática leve (LCTL) es tres veces más común que la lesión cerebral moderada y severa combinada 1, se necesita un modelo fiable de LCTL para facilitar la investigación en relación con la fisiopatología, los resultados neurobiológicos y de comportamiento, y estrategias terapéuticas. Por ejemplo, debido en parte a las limitaciones de los modelos animales actuales 2, en la última década ha habido más de 200 fallidos ensayos clínicos con medicamentos para el tratamiento de TBI 3. Cuando los sistemas de modelado se generan para los estudios de investigación traslacional, la aplicabilidad de los resultados dependen de la validez del modelo implementado. Para el estudio de LCTL / conmoción cerebral, un modelo animal fiable no sólo imitar la fuerzas biomecánicas responsable de etiología lesión, sino que también inducen síntomas consistentes con los reportados por la población clínicamente relevante. Además, dado que los niños están en riesgo particularmente alto de LCTL, sistemas de modelado óptimo sería aplicable a los roedores jóvenes y menores de edad, además de sus equivalentes adultos. Análisis biomecánicos de circunstancias en las que los atletas han sufrido mTBIs o lesiones cerebrales concussive indican que los factores predictivos más críticos para la lesión son la aceleración rápida y cabeza impactos de alta energía 4. La mayoría de los modelos de roedores actualmente empleados para la inducción de TBI permite poco o ningún movimiento de la cabeza 5 (para revisión ver 2). El modelo descrito aquí, entrega un impacto de alta velocidad a la cabeza de una rata juvenil físicamente desenfrenada que se acompaña de una rotación de 180 ° y la caída libre que aplica fuerzas de aceleración / deceleración a la cabeza y el cuerpo del sujeto. Taquí son dos ventajas principales asociados a esta técnica de caída de peso modificado para la inducción de LCTL. En primer lugar, el modelo produce conmoción clínicamente relevante como sintomatología sin causar un daño claro al cerebro (para una descripción completa de los resultados conductuales ver 6). También en consonancia con los informes clínicos de síndrome post-conmoción, esta técnica peso soltar modificado produce resultados heterogéneos. Aunque los efectos de la LCTL son significativas, existe una variación considerable entre los roedores que experimentaron una LCTL cuando se examina en múltiples medidas de resultado. En segundo lugar, el método permite el estudio de LCTL repetitivo 7. Como la mayoría de los modelos de TCE existentes infligir tales lesiones graves, a menudo es difícil para inducir una segunda lesión, y casi imposible estudiar TBI repetitiva sin grandes daños a toda la corteza. Por lo tanto, la razón principal para el uso de la técnica de caída de peso modificado para la inducción de LCTL es producir una lesión que representa más de cerca la patofisiología y sintomatología de la conmoción cerebral y repetitivo TBI en poblaciones juveniles. Con la creciente incidencia de LCTL relacionado con los deportes, caídas, y accidentes automovilísticos, especialmente durante la infancia, este modelo roedor única de LCTL proporciona a los investigadores una herramienta valiosa para el estudio de la lesión cerebral conmoción similar que se puede aplicar fácilmente a múltiples hit paradigmas.

<table><tbody><tr><td>Brass Weights</td><td>Ginsberg Scientific</td><td>7-2500-2</td><td>Need to have metal loop attached to base</td></tr><tr><td>Alluminum Foil</td><td>Alcan</td><td></td><td>Available at most grocery stores</td></tr><tr><td>Masking Tape</td><td></td><td></td><td>Commercially available&amp;nbsp;</td></tr><tr><td>U-Shaped Plastic Stand</td><td></td><td></td><td>Constructed by Laboratory</td></tr><tr><td>Clamp Stand</td><td>Sigma-Aldrich</td><td>Z190357</td><td></td></tr><tr><td>Plastic Guide Tube</td><td></td><td></td><td>Could be constructed or purchased at a hardware store</td></tr><tr><td>Fishing Line</td><td>Angler 10lb&amp;nbsp;</td><td></td><td>Purchased from a sporting goods retailer&amp;nbsp;</td></tr><tr><td>Isoflurane</td><td>Pharmaceutical Partners of Canada</td><td>DIN 02237518</td><td>Inhalation Anesthetic</td></tr><tr><td>Topical Lidocaine (30ml)</td><td>Astra Zeneca</td><td>DIN 0001694</td><td>Xylocaine Jelly 2%&amp;nbsp;</td></tr><tr><td>Cotton Swabs</td><td></td><td></td><td>Commercially available&amp;nbsp;</td></tr><tr><td>Heating Pad - 3 heat setting</td><td></td><td></td><td>Commercially available&amp;nbsp;</td></tr><tr><td>Stop Watch</td><td>Sportline</td><td>L303</td><td>Purchased from a sporting goods retailer&amp;nbsp;</td></tr><tr><td>Video Camera</td><td>Sony</td><td>HDR-CX260V</td><td></td></tr><tr><td>Sprague Dawley Rats</td><td>Charles River Laboratories</td><td>SAS SD 40</td><td>Male and females ordered from Charles River Laboratories and pups bred in-house</td></tr><tr><td>Balance Beam</td><td></td><td></td><td>Constructed by Laboratory</td></tr></tbody></table>

a novel model of mild traumatic brain injury for juvenile rats

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor vehicle accidents, and falls, a reliable animal model of mTBI had previously not been developed for this important aspect of development. The modified weight-drop technique employs a glancing impact to the head of a freely moving rodent transmitting acceleration, deceleration, and rotational forces upon the brain. When applied to juvenile rats, this modified weight-drop technique induced clinically relevant behavioural outcomes that were representative of post-concussion symptomology. The technique is a rapidly applied procedure with an extremely low mortality rate, rendering it ideal for high-throughput studies of therapeutics. In addition, because the procedure involves a mild injury to a closed head, it can easily be used for studies of repetitive brain injury. Owing to the simplistic nature of this technique, and the clinically relevant biomechanics of the injury pathophysiology, the modified weight-drop technique provides researchers with a reliable model of mTBI that can be used in a wide variety of behavioural, molecular, and genetic studies.

La técnica peso soltar modificado descrito anteriormente es un método fiable para la inducción de la lesión cerebral traumática leve (LCTL) en ratas jóvenes. Utilizando un peso impacto de 150 g, esta técnica se ha aplicado con éxito en ratas jóvenes, que van desde 50 hasta 120 g. Además, el procedimiento se puede repetir fácilmente en los mismos animales para el estudio de repetitivo LCTL. Aunque los animales que experimentan una sola exhibición LCTL un aumento en el tiempo de lanzamiento al derecho (Figura 3), aparezcan sorprendieron al despertarse, que reanuden rápidamente las actividades normales y son visualmente indistinguibles de los animales sham-heridos. Dado que la lesión es leve, lidocaína tópica que elimina cualquier dolor asociado con el impacto de mirar, es el único analgésico necesario. Esto es importante para la investigación como se conoce a medicamentos para el dolor de interferir con los procesos inflamatorios y recuperación típicas. Debido a la falta de sintomatología manifiesta, la tarea de balancín es un fiable paraol que se puede utilizar para validar la inducción de la LCTL. Es importante tener en cuenta, que no todos los animales que experimentan un LCTL exhibirán los déficits en la tarea de balancín, pero como grupo, las ratas jóvenes con un LCTL demostrar la pierna-pie se desliza mucho más traseras cuando se compara con ratas jóvenes con una lesión simulada (Figura 4). Otra característica clave de esta técnica peso soltar modificado es la falta de restricción aplicada a la rata de menores durante la inducción de la lesión. Mediante la entrega de un golpe de refilón a la cabeza seguido de una rápida aceleración rotacional y desaceleración, este modelo representa más de cerca las fuerzas biomecánicas atribuidos a LCTL y conmoción cerebral. Cuando se aplica este procedimiento a ratas jóvenes o ratones adultos, las tasas de mortalidad son extremadamente bajos (7/202 animales jóvenes ~ 3,4% de tasa de mortalidad), y fractura de cráneo y hemorragia intracraneal son excepcionalmente raros 6,7. Además, el modelo produce sy clínicamente relevantemptomology. Roedores menores que experimentaron una sola LCTL demostraron déficits de equilibrio y de motor comportamientos, junto con déficits en la función ejecutiva, el aumento de los comportamientos depresivos similares, y las interacciones sociales alteradas 6,9. Del mismo modo, los ratones adultos también muestran déficits de equilibrio y coordinación leves que se recuperan con el tiempo 7. Finalmente, la inducción de LCTL el uso de este modelo requiere anestesia mínimo y no implica la preparación quirúrgica o madriguera en el cráneo. Resultados por lo tanto no están sesgadas por confusión efectos inflamatorios o inmunológicos desencadenados por la cirugía o anestesia. Además, el tiempo de recuperación rápida y la falta de heridas abiertas permite el inicio de los paradigmas de ensayo adicionales que se produzca poco después de roedores experimentan el LCTL. <img alt="Figura 1" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig1highres.jpg" width="500" /> Figura 1: </strong<html> &gt; C artoon representación de la forma de U etapa de plástico y la recogida de esponja con todas las dimensiones pertinentes. Una distancia de 10 cm debe mantenerse entre la esponja recogida y la parte superior de la etapa de plástico para garantizar la rata juvenil tiene tiempo suficiente para completar el 180 rotación °. <img alt="Figura 2" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig2highres.jpg" width="500" /> Figura 2: (A) la representación fotográfica de la plataforma de la inducción de la lesión. La rata juvenil se coloca en el pecho abajo en el papel de aluminio anotado para que la cabeza está directamente debajo del peso que cae. (B) Vista lateral de la plataforma de la inducción de lesiones. (C) la demostración fotográfico del peso utilizado en la inducción de la LCTL . subir / 51820 / 51820fig3highres.jpg &quot;width =&quot; 500 &quot;/&gt; Figura 3: Representación gráfica de las diferencias promedio en el tiempo a derecha entre ratas jóvenes que experimentaron un solo LCTL y ratas jóvenes que experimentaron una lesión simulada (* p &lt;0,01) Las ratas que recibieron una exposición LCTL un aumento significativo en el. duración de tiempo necesario para enderezarse desde la posición supina. <img alt="Figura 4" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig4highres.jpg" width="500" /> Figura 4: Representación gráfica de la media de la pierna-pie se desliza traseras exhibidos en la tarea Walking Beam de ratas jóvenes que experimentó un solo LCTL y ratas jóvenes que experimentaron una lesión simulada (* p &lt;0,05).

Watch this Scientific Journal Video about A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats at JoVE.com

A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats

The modified weight-drop technique is an easy, cost-effective procedure used for the induction of mild traumatic brain injury in juvenile rats. This novel technique produces clinically relevant symptomology that will advance the study of mild traumatic brain injury (mTBI) and concussion.

Un nuevo modelo de leve lesión cerebral traumática para ratas jóvenes

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor ...

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Research

JoVE Journal

Medicine

23.5K vistas.  University of Calgary. The modified weight-drop technique is an easy, cost-effective procedure used for the induction of mild traumatic brain injury in juvenile rats. This novel technique produces clinically relevant symptomology that will advance the study of mild traumatic brain injury (mTBI) and concussion. 

Video: A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats

Detecting Behavioral Deficits in Rats After Traumatic Brain Injury

With the increasing incidence of traumatic brain injury (TBI) in both civilian and military populations, TBI is now considered a chronic disease; however, few studies have investigated the long-term effects of injury in rodent models of TBI. Shown here are behavioral measures that are well-established in TBI research for times early after injury, such as two weeks, until two months. Some of these methods have previously been used at later times after injury, up to one year, but by very few laboratories. The methods demonstrated here are a short neurological assessment to test reflexes, a Beam-Balance to test balance, a Beam-Walk to test balance and motor coordination, and a working memory version of the Morris water maze that can be sensitive to deficits in reference memory. Male rats were handled and pre-trained to neurological, balance, and motor coordination tests prior to receiving parasagittal fluid percussion injury (FPI) or sham injury. Rats can be tested on the short neurological assessment (neuroscore), the beam-balance, and the Beam-Walk multiple times, while testing on the water maze can only be done once. This difference is because rats can remember the task, thus confounding the results if repeated testing is attempted in the same animal. When testing from one to three days after injury, significant differences are detected in all three non-cognitive tasks. However, differences in the Beam-Walk task were not detectable at later time points (after 3 months). Deficits were detected at 3 months in the Beam-Balance and at 6 months in the neuroscore. Deficits in working memory were detected out to 12 months after injury, and a deficit in a reference memory first appeared at 12 months. Thus, standard behavioral tests can be useful measures of persistent behavioral deficits after FPI.

The goal of the behavioral tests presented here is to detect functional deficits in rats after traumatic brain injury. Four specific tests are presented that detect deficits in behaviors to reflect the damage to specific brain areas at times extending to one year after injury.

Detección de déficits conductuales en ratas después de la lesión cerebral traumática

With the increasing incidence of traumatic brain injury (TBI) in both civilian and military populations, TBI is now considered a chronic disease; however, ...

Investigación

Comportamiento

Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social hierarchies that are often based on dominant-submissive relationships. The dominant-submissive relationship is a normal behavioral pattern among the individuals of a species. Traumatic brain injury is a frequent cause of social interaction impairment and the reorganization of dominant-submissive relationships in animal pairs. This protocol describes submissive behavior in adult male Sprague-Dawley rats after the induction of traumatic brain injury using a fluid-percussion model compared to naive rats through a series of dominant-submissive tests performed between 29 days and 33 days after induction. The dominant-submissive behavior test shows how brain injury can induce submissive behavior in animals competing for food. After traumatic brain injury, the rodents were more submissive, as indicated by them spending less time at the feeder and being less likely to arrive first at the trough compared to the control animals. According to this protocol, submissive behavior develops after traumatic brain injury in adult male rats.

The present protocol describes a rat model of fluid percussion-induced traumatic brain injury followed by a series of behavioral tests to understand the development of dominant and submissive behavior. Using this model of traumatic brain injury in conjunction with specific behavioral tests enables the study of social impairments following brain injury.

Evaluación del comportamiento dominante-sumiso en ratas adultas después de una lesión cerebral traumática

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social ...

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal neurological deficits and even amnesia. Athletes participating in contact sports are at high risk of exposure to large number of mTBIs. In terms of the level of injury in a sporting athlete, a mTBI is defined as a mild injury that does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Despite previous attempts to model mTBI in mice and rats, many have reported gross adverse effects including skull fractures, intracerebral bleeding, axonal injury and neuronal cell death. Herein, we describe our highly reproducible animal model of mTBI that reproduces clinically relevant symptoms. This model uses a custom made pneumatic impactor device to deliver a closed-head trauma. This impact is made under precise velocity and deformation parameters, creating a reliable and reproducible model to examine the mechanisms that contribute to effects of single or repetitive concussive mTBI.

Athletes absorb several hundred mild traumatic brain injuries (mTBI)/concussions every year; however, the consequence of these on the brain is poorly understood. Therefore, an animal model of single and repetitive mTBI that consistently replicates clinically relevant symptoms provides the means to advance the study of mTBI and concussion.

Un Modelo de Ratón de Único y Repetitivo Lesión Cerebral Traumática Leve

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal ...

Medicina

A Novel and Translational Rat Model of Concussion Combining Force and Rotation with In Vivo Cerebral Microdialysis

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to altered neurotransmission. Indeed, cerebral microdialysis studies in rodents have demonstrated an excessive extracellular glutamate release in the hippocampus within the first 10 min following trauma. Microdialysis offers the clear advantage of in vivo neurotransmitter continuous sampling while not having to sacrifice the animal. In addition to the aforementioned technique, a closed head injury model that exerts rapid acceleration and deceleration of the head and torso is needed, as such a factor is not available in many other animal models. The Wayne State weight-drop model mimics this essential component of human craniocerebral trauma, allowing the induction of an impact on the head of an unrestrained rodent with a falling weight. Our novel and translational rat model combines cerebral microdialysis with the Wayne State weight-drop model to study, in lightly anesthetized and unrestrained adult rats, the acute changes in extracellular neurotransmitter levels following concussion. In this protocol, the microdialysis probe was inserted inside the hippocampus as region of interest, and was left inserted in the brain at impact. There is a high density of terminals and receptors in the hippocampus, making it a relevant region to document altered neurotransmission following concussion. When applied to adult Sprague-Dawley rats, our combined model induced increases in hippocampal extracellular glutamate concentrations within the first 10 min, consistent with the previously reported post-concussion symptomology. This combined weight-drop model provides a reliable tool for researchers to study early therapeutic responses to concussions in addition to repetitive brain injury, since this protocol induces a closed-head mild trauma.

Neurotransmitter alteration is a mechanism of neural dysfunction that occurs after concussion and contributes to the sometimes-catastrophic long-term consequences. This rat model combines microdialysis, allowing in vivo neurotransmitter quantification, with a weight-drop technique exerting rapid acceleration and deceleration of the head and torso, an important factor of human craniocerebral trauma.

Un modelo de rata novedoso y traslacional de la conmoción cerebral que combina la fuerza y la rotación con la microdiálisis cerebral In Vivo

Persistent cognitive and motor symptoms are known consequences of concussions/mild traumatic brain injury (mTBIs) that can be partly attributable to ...

Neurociencias

Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous variability and heterogeneity (age, gender, type of trauma, other possible pathologies, etc.), animal models play a key role in unraveling factors that are limitations in clinical research. They provide a standardized and controlled setting to investigate the biological mechanisms of injury and repair following TBI. However, not all animal models mimic the diffuse and subtle nature of mTBI effectively. For example, the commonly used controlled cortical impact (CCI) and lateral fluid percussion injury (LFPI) models make use of a craniotomy to expose the brain and induce widespread focal trauma, which are not commonly seen in mTBI. Therefore, these experimental models are not valid to mimic mTBI. Thus, an appropriate model should be used to investigate mTBI. The Marmarou weight drop model for rats induces similar microstructural alterations and cognitive impairments as seen in patients who sustain mild trauma; therefore, this model was selected for this protocol. Conventional computed tomography and magnetic resonance imaging (MRI) scans commonly show no damage following a mild injury, because mTBI induces often only subtle and diffuse injuries. With diffusion weighted MRI, it is possible to investigate microstructural properties of brain tissue, which can provide more insight into the microscopic alterations following mild trauma. Therefore, the goal of this study is to obtain quantitative information of a selected region-of-interest (i.e., hippocampus) to follow up disease progression after obtaining a mild and diffuse brain injury.

The overall goal of this procedure is to obtain quantitative microstructural information of the hippocampus in a rat with mild traumatic brain injury. This is done using an advanced diffusion-weighted magnetic resonance imaging protocol and region-of-interest based analysis of parametric diffusion maps.

Imágenes de difusión avanzada en el hipocampo de ratas con lesión cerebral traumática leve

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous ...

Electromagnetic Controlled Closed-Head Model of Mild Traumatic Brain Injury in Mice

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and understanding the mechanisms of how a TBI alters brain function. The availability of multiple animal models of TBI is necessary to model the different aspects and severities of TBI seen in people. This manuscript describes the use of a midline closed head injury (CHI) to develop a mouse model of mild TBI. The model is considered mild because it does not produce structural brain lesions based on neuroimaging or gross neuronal loss. However, a single impact creates enough pathology that cognitive impairment is measurable at least 1 month after injury. A step-by-step protocol to induce a CHI in mice using a stereotaxically guided electromagnetic impactor is defined in the paper. The benefits of the mild midline CHI model include the reproducibility of the injury-induced changes with low mortality. The model has been temporally characterized up to 1 year after the injury for neuroimaging, neurochemical, neuropathological, and behavioral changes. The model is complementary to open skull models of controlled cortical impact using the same impactor device. Thus, labs can model both mild diffuse TBI and focal moderate-to-severe TBI with the same impactor.

The protocol describes mild traumatic brain injury in a mouse model. In particular, a step-by-step protocol to induce a mild midline closed head injury and the characterization of the animal model is fully explained.

Modelo electromagnético controlado de cabeza cerrada de lesión cerebral traumática leve en ratones

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and ...

Assessing Changes in Synaptic Plasticity Using an Awake Closed-Head Injury Model of Mild Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of closed-head mTBI in the preclinical setting to increase translatability to the clinical population. The awake closed-headed injury (ACHI) model uses a modified controlled cortical impactor to deliver closed-headed injury, inducing clinically relevant behavioral deficits without the need for a craniotomy or the use of an anesthetic.
This technique does not normally induce fatalities, skull fractures, or brain bleeds, and is more consistent with being a mild injury. Indeed, the mild nature of the ACHI procedure makes it ideal for studies investigating repetitive mTBI (r-mTBI). Growing evidence indicates that r-mTBI can result in a cumulative injury that produces behavioral symptoms, neuropathological changes, and neurodegeneration. r-mTBI is common in youths playing sports, and these injuries occur during a period of robust synaptic reorganization and myelination, making the younger population particularly vulnerable to the long-term influences of r-mTBI.
Further, r-mTBI occurs in cases of intimate partner violence, a condition for which there are few objective screening measures. In these experiments, synaptic function was assessed in the hippocampus in juvenile rats that had experienced r-mTBI using the ACHI model. Following the injuries, a tissue slicer was utilized to make hippocampal slices to evaluate bidirectional synaptic plasticity in the hippocampus at either 1 or 7 days following the r-mTBI. Overall, the ACHI model provides researchers with an ecologically valid model to study changes in synaptic plasticity following mTBI and r-mTBI.

Here, it is demonstrated how an awake closed-head injury model can be used for examining the effects of repeated mild traumatic brain injury (r-mTBI) on synaptic plasticity in the hippocampus. The model replicates important features of r-mTBI in patients and is used in conjunction with in vitro electrophysiology.

Evaluación de los cambios en la plasticidad sináptica utilizando un modelo de lesión cerebral traumática leve con vigilia

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of ...

Validación de la respuesta a las lesiones y las evaluaciones conductuales en un modelo de rata mTBI

Rat Model of Closed-Head Mild Traumatic Injury and its Validation

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful insights, developing a stable and reproducible animal model is essential. In this study, we report a detailed description of a closed-head mTBI model and a representative validation method using Sprague-Dawley rats to verify the modeling effect. The model involves dropping a 550 g mass weight from a height of 100 cm directly onto the head of a rat on a destructible surface, followed by a 180-degree turn. To assess the injury, rats underwent a series of neurobehavioral assessments 10 min post-injury, including time of loss of consciousness, first seeking-behavior time, escape ability, and beam balance ability test. During the acute and subacute stages following the injury, behavioral tests were conducted to assess motor coordination ability (Beam task), anxiety (Open Field test), and learning and memory abilities (Morris Water Maze test). The closed-head mTBI model produced a consistent injury response with minimal mortality and replicated real-life situations. The validation method effectively verified the model development and ensured the stability and consistency of the model.

Autor destacado: Avance en la investigación de lesiones cerebrales traumáticas: un modelo de cabeza cerrada para una replicación precisa y una evaluación rápida 

Here, we present a closed-head mild traumatic brain injury (mTBI) rat model and its validation exhibiting remarkable similarity to human mTBI concerning behavioral manifestations during the acute and subacute stages.

Modelo de Rata de Lesión Traumática Leve de Cabeza Cerrada y su Validación

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful ...

Un nuevo modelo de leve lesión cerebral traumática para ratas jóvenes

Resumen

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