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 border="0" cellpadding="0" cellspacing="0" width="824">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Brass Weights</td>
			<td style="width:155px;">Ginsberg Scientific</td>
			<td style="width:187px;">7-2500-2</td>
			<td style="width:219px;">Need to have metal loop attached to base</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Alluminum Foil</td>
			<td style="width:155px;">Alcan</td>
			<td style="width:187px;"></td>
			<td>Available at most grocery stores</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Masking Tape</td>
			<td style="width:155px;"></td>
			<td style="width:187px;"></td>
			<td>Commercially available&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">U-Shaped Plastic Stand</td>
			<td style="width:155px;"></td>
			<td style="width:187px;"></td>
			<td>Constructed by Laboratory</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Clamp Stand</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td style="width:187px;">Z190357</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Plastic Guide Tube</td>
			<td style="width:155px;"></td>
			<td style="width:187px;"></td>
			<td>Could be constructed or purchased at a hardware store</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Fishing Line</td>
			<td style="width:155px;">Angler 10lb&#160;</td>
			<td style="width:187px;"></td>
			<td>Purchased from a sporting goods retailer&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:264px;">Isoflurane</td>
			<td style="width:155px;">Pharmaceutical Partners of Canada</td>
			<td style="width:187px;">DIN 02237518</td>
			<td>Inhalation Anesthetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Topical Lidocaine (30ml)</td>
			<td style="width:155px;">Astra Zeneca</td>
			<td style="width:187px;">DIN 0001694</td>
			<td>Xylocaine Jelly 2%&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Cotton Swabs</td>
			<td style="width:155px;"></td>
			<td style="width:187px;"></td>
			<td>Commercially available&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Heating Pad - 3 heat setting</td>
			<td style="width:155px;"></td>
			<td style="width:187px;"></td>
			<td>Commercially available&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Stop Watch</td>
			<td style="width:155px;">Sportline</td>
			<td style="width:187px;">L303</td>
			<td>Purchased from a sporting goods retailer&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">Video Camera</td>
			<td style="width:155px;">Sony</td>
			<td style="width:187px;">HDR-CX260V</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:264px;">Sprague Dawley Rats</td>
			<td style="width:155px;">Charles River Laboratories</td>
			<td style="width:187px;">SAS SD 40</td>
			<td>Male and females ordered from Charles River Laboratories and pups bred in-house</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:264px;">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

23.4K 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

Acute and Chronic Tactile Sensory Testing after Spinal Cord Injury in Rats

Spinal cord injury (SCI) impairs sensory systems causing allodynia1-8. To identify cellular and molecular causes of allodynia, sensitive and valid sensory testing in rat SCI models is needed. However, until recently, no single testing approach had been validated for SCI so that standardized methods have not been implemented across labs. Additionally, available testing methods could not be implemented acutely or when severe motor impairments existed, preventing studies of the development of SCI-induced allodynia3. Here we present two validated sensory testing methods using von Frey Hair (VFH) monofilaments which quantify changes in tactile sensory thresholds after SCI4-5. One test is the well-established Up-Down test which demonstrates high sensitivity and specificity across different SCI severities when tested chronically5. The other test is a newly-developed dorsal VFH test that can be applied acutely after SCI when allodynia develops, prior to motor recovery4-5. Each VFH monofilament applies a calibrated force when touched to the skin of the hind paw until it bends. In the up-down method, alternating VFHs of higher or lower forces are used on the plantar L5 dermatome to delineate flexor withdrawal thresholds. Successively higher forces are applied until withdrawal occurs then lower force VFHs are used until withdrawal ceases. The tactile threshold reflects the force required to elicit withdrawal in 50% of the stimuli. For the new test, each VFH is applied to the dorsal L5 dermatome of the paw while the rat is supported by the examiner. The VFH stimulation occurs in ascending order of force until at least 2 of 3 applications at a given force produces paw withdrawal. Tactile sensory threshold is the lowest force to elicit withdrawal 66% of the time. Acclimation, testing and scoring procedures are described. Aberrant trials that require a retest and typical trials are defined. Animal use was approved by Ohio State University Animal Care and Use Committee.

We describe two tactile sensory testing methods for acute or chronic periods of spinal cord injury in rats. These validated procedures can detect the development and maintenance of allodynia-like sensations.

Aguda y crónica Prueba sensorial táctil después de la lesión de la médula espinal en ratas

Spinal cord injury (SCI) impairs sensory systems causing allodynia1-8. To identify cellular and molecular causes of allodynia, sensitive and valid sensory ...

Investigación

Medicina

A Contusion Model of Severe Spinal Cord Injury in Rats

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is described to obtain a consistent model of severe SCI. Use of a stereotactic frame and computer controlled impactor allows for creation of reproducible injury. Hypothermia and urinary tract infection pose significant challenges in the post-operative period. Careful monitoring of animals with daily weight recording and bladder expression allows for early detection of post-operative complications. The functional results of this contusion model are equivalent to transection models. The contusion model can be utilized to evaluate the efficacy of both neuroprotective and neuroregenerative approaches.

A contusion model of severe spinal cord injury is described. Detailed pre-operative, operative and post-operative steps are described to obtain a consistent model.

Un modelo Contusión de la lesión de la médula espinal severa en ratas

The translational potential of novel treatments should be investigated in severe spinal cord injury (SCI) contusion models. A detailed methodology is ...

A Novel Vertebral Stabilization Method for Producing  Contusive Spinal Cord Injury

Clinically-relevant animal cervical spinal cord injury (SCI) models are essential for developing and testing potential therapies; however, producing reliable cervical SCI is difficult due to lack of satisfactory methods of vertebral stabilization. The conventional method to stabilize the spine is to suspend the rostral and caudal cervical spine via clamps attached to cervical spinous processes. &#160;However, this method of stabilization fails to prevent tissue yielding during the contusion as the cervical spinal processes are too short to be effectively secured by the clamps (Figure 1). &#160;Here we introduce a new method to completely stabilize the cervical vertebra at the same level of the impact injury. &#160;This method effectively minimizes movement of the spinal column at the site of impact, which greatly improves the production of consistent SCIs. &#160;We provide visual description of the equipment (Figure 2-4), methods, and a step-by-step protocol for the stabilization of the cervical 5 vertebra (C5) of adult rats, to perform laminectomy (Figure 5) and produce a contusive SCI thereafter. &#160;Although we only demonstrate a cervical hemi-contusion using the NYU/MASCIS impactor device, this vertebral stabilization technique can be applied to other regions of the spinal cord, or be adapted to other SCI devices. &#160;Improving spinal cord exposure and fixation through vertebral stabilization may be valuable for producing consistent and reliable injuries to the spinal cord. &#160;This vertebral stabilization method can also be used for stereotactic injections of cells and tracers, and for imaging using two-photon microscopy in various neurobiological studies.

Vertebral stabilization is necessary for minimizing variability, and for producing consistent experimental spinal cord injuries.&#160; Using a customized stabilizing apparatus in conjunction with the NYU/MASCIS impactor device, we have demonstrated here the proper equipment and procedure for generating reproducible hemi-contusive cervical (C5) spinal cord injuries in adult rats.

Una novela Vertebral Método de Estabilización para Producir contuso Lesiones de la Médula Espinal

Clinically-relevant animal cervical spinal cord injury (SCI) models are essential for developing and testing potential therapies; however, producing ...

Stretch in Brain Microvascular Endothelial Cells (cEND) as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying mechanisms involved in it are useful for treatment. There are both in vivo and in vitro methods available for this purpose. In vivo models can mimic actual head injury as it occurs during TBI. However, in vivo techniques may not be exploited for studies at the cell physiology level. Hence, in vitro methods are more advantageous for this purpose since they provide easier access to the cells and the extracellular environment for manipulation.
Our protocol presents an in vitro model of TBI using stretch injury in brain microvascular endothelial cells. It utilizes pressure applied to the cells cultured in flexible-bottomed wells. The pressure applied may easily be controlled and can produce injury that ranges from low to severe. The murine brain microvascular endothelial cells (cEND) generated in our laboratory is a well-suited model for the blood brain barrier (BBB) thus providing an advantage to other systems that employ a similar technique. In addition, due to the simplicity of the method, experimental set-ups are easily duplicated. Thus, this model can be used in studying the cellular and molecular mechanisms involved in TBI at the BBB.

Stretch in Brain Microvascular Endothelial Cells cEND as an In Vitro Traumatic Brain Injury Model of the Blood Brain Barrier

In vitro traumatic brain injury models are being developed to reproduce in vivo brain deformation. Stretch-induced injury has been employed for astrocytes, neurons, glial cells, aortic, and brain endothelial cells. However, our system uses a blood brain barrier (BBB) model that possesses properties constituting a legitimate model of the BBB to establish an in vitro&#160;TBI model.

Estirar en Brain células endoteliales microvasculares (CEND) como<em&gt; In Vitro</em&gt; Lesión cerebral traumática Modelo de la barrera hematoencefálica

Due to the high mortality incident brought about by traumatic brain injury (TBI), methods that would enable one to better understand the underlying ...

Controlled Cortical Impact Model for Traumatic Brain Injury

Every year over a million Americans suffer a traumatic brain injury (TBI). Combined with the incidence of TBIs worldwide, the physical, emotional, social, and economical effects are staggering. Therefore, further research into the effects of TBI and effective treatments is necessary. The controlled cortical impact (CCI) model induces traumatic brain injuries ranging from mild to severe. This method uses a rigid impactor to deliver mechanical energy to an intact dura exposed following a craniectomy. Impact is made under precise parameters at a set velocity to achieve a pre-determined deformation depth. Although other TBI models, such as weight drop and fluid percussion, exist, CCI is more accurate, easier to control, and most importantly, produces traumatic brain injuries similar to those seen in humans. However, no TBI model is currently able to reproduce pathological changes identical to those seen in human patients. The CCI model allows investigation into the short-term and long-term effects of TBI, such as neuronal death, memory deficits, and cerebral edema, as well as potential therapeutic treatments for TBI.

Traumatic brain injuries (TBIs) remain a serious health problem. Using the controlled cortical impact surgery model, research on the effects of TBI and possible treatment methods may be performed.

Controlado Modelo de Impacto cortical de la lesión cerebral traumática

Every year over a million Americans suffer a traumatic brain injury (TBI).  Combined with the incidence of TBIs worldwide, the physical, emotional, ...

Renal Ischaemia Reperfusion Injury: A Mouse Model of Injury and Regeneration

Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable during renal transplantation. Experimental models that accurately and reproducibly recapitulate renal IRI are crucial in dissecting the pathophysiology of AKI and the development of novel therapeutic agents. Presented here is a mouse model of renal IRI that results in reproducible AKI. This is achieved by a midline laparotomy approach for the surgery with one incision allowing both a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia of the left kidney. By careful monitoring of the clamp position and body temperature during the period of ischaemia this model achieves reproducible functional and structural injury. Mice sacrificed 24 hr&#160;following surgery demonstrate loss of renal function with elevation of the serum or plasma creatinine level as well as structural kidney damage with acute tubular necrosis evident. Renal function improves and the acute tissue injury resolves during the course of 7 days following renal IRI such that this model may be used to study renal regeneration. This model of renal IRI has been utilized to study the molecular and cellular pathophysiology of AKI as well as analysis of the subsequent renal regeneration.

The mouse model of renal ischaemia reperfusion injury described here comprises of a right nephrectomy that provides control tissue and clamping of the left renal pedicle to induce ischaemia that results in acute kidney injury. This model uses a midline laparotomy approach with all steps performed via one incision.

La isquemia reperfusión renal: un modelo de ratón de la lesión y regeneración

Renal ischaemia reperfusion injury (IRI) is a common cause of acute kidney injury (AKI) in patients and occlusion of renal blood flow is unavoidable ...

A Tissue Displacement-based Contusive Spinal Cord Injury Model in Mice

Producing a consistent and reproducible contusive spinal cord injury (SCI) is critical to minimizing behavioral and histological variabilities between experimental animals. Several contusive SCI models have been developed to produce injuries using different mechanisms. The severity of the SCI is based on the height that a given weight is dropped, the injury force, or the spinal cord displacement. In the current study, we introduce a novel mouse contusive SCI device, the Louisville Injury System Apparatus (LISA) impactor, which can create a displacement-based SCI with high injury velocity and accuracy. This system utilizes laser distance sensors combined with advanced software to produce graded and highly-reproducible injuries. We performed a contusive SCI at the 10th thoracic vertebral (T10) level in mice to demonstrate the step-by-step procedure. The model can also be applied to the cervical and lumbar spinal levels.

We introduce a tissue displacement-based contusive spinal cord injury model that can produce a consistent contusive spinal cord injury in adult mice.

Un modelo de lesión de la médula espinal contundente basado en el desplazamiento de tejidos en ratones

Producing a consistent and reproducible contusive spinal cord injury (SCI) is critical to minimizing behavioral and histological variabilities between ...

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 ...

Spinal Cord Lateral Hemisection and Asymmetric Behavioral Assessments in Adult Rats

Incomplete spinal cord injury (SCI) often leads to impairments of sensorimotor functions and is clinically the most frequent type of SCI. Human Brown-S&#233;quard syndrome&#160;is a common type of incomplete SCI caused by a lesion to one half of the spinal cord which results in paralysis and loss of&#160;proprioception&#160;on the same (or ipsilesional) side as the injury, and loss of pain and temperature sensation on the opposite (or contralesional) side. Adequate methodologies for producing a spinal cord lateral hemisection (HX) and assessing neurological impairments are essential to establish a reliable animal model of Brown-S&#233;quard syndrome. Although lateral hemisection model plays a pivotal role in basic and translational research, standardized protocols for creating such a hemisection and assessing unilateralized function are lacking. The goal of this study is to describe step-by-step procedures to produce a rat spinal lateral HX at the 9th thoracic (T9) vertebral level. We, then, describe a combined behavior scale for HX (CBS-HX) that provides a simple and sensitive assessment of asymmetric neurological performance for unilateral SCI. The CBS-HX, ranging from 0 to 18, is composed of 4 individual assessments which include unilateral hindlimb stepping (UHS), coupling, contact placing, and grid walking. For CBS-HX, the ipsilateral and contralateral hindlimbs are assessed separately. We found that, after a T9 HX, the ipsilateral hindlimb showed impaired behavior function whereas the contralateral hindlimb showed substantial recovery. The CBS-HX effectively discriminated behavioral functions between ipsilateral and contralateral hindlimbs and detected temporal progression of recovery of the ipsilateral hindlimb. The CBS-HX components can be analyzed separately or in combination with other measures when needed. Although we only provided visual descriptions of the surgical procedures and behavioral assessments of a thoracic HX, the principle may be applied to other incomplete SCIs and at other levels of the injury.

Here we describe surgical procedures to produce a reliable spinal cord lateral hemisection (HX) at the 9th thoracic level in adult rats and neurobehavioral assessments designed for detecting asymmetric deficits after such a unilateral injury.

Hemisección lateral de la médula espinal y evaluaciones conductuales asimétricas en ratas adultas

Incomplete spinal cord injury (SCI) often leads to impairments of sensorimotor functions and is clinically the most frequent type of SCI. Human ...

Semi-quantitative Assessment Using [18F]FDG Tracer in Patients with Severe Brain Injury

Patients with severe traumatic brain injury (sTBI) have difficulty knowing whether they are accurately expressing their thoughts and emotions because of disorders of consciousness, disrupted higher brain function, and verbal disturbances. As a consequence of an insufficient ability to communicate, objective evaluations are needed from family members, medical staff, and caregivers. One such evaluation is the assessment of functioning brain areas. Recently, multimodal brain imaging has been used to explore the function of damaged brain areas. [18F]-fluorodeoxyglucose positron emission tomography-computed tomography ([18F]FDG-PET/CT) is a successful tool for examining brain function. However, the assessment of brain glucose metabolism based on [18F]FDG-PET/CT is not standardized and depends on several varying parameters, as well as the patient&#39;s condition. Here, we describe a series of semiquantitative assessment protocols for a region-of-interest (ROI) image analysis using self-produced [18F]FDG tracers in patients with sTBI. The protocol focuses on screening the participants, preparing the [18F]FDG tracer in the hot lab, scheduling the acquisition of [18F]FDG-PET/CT brain images, and measuring glucose metabolism using the ROI analysis from a targeted brain area.

Semi-quantitative Assessment Using [18F]FDG Tracer in Patients with Severe Brain Injury

[18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography is useful for studying glucose metabolism related to brain function. Here, we present a protocol for an [18F]FDG tracer set-up and semiquantitative assessment of the region-of-interest analysis for targeted brain areas associated with clinical manifestations in patients with severe traumatic brain injury.

Evaluación semicuantitativa usando [18F] FDG trazador en pacientes con lesión cerebral grave

Patients with severe traumatic brain injury (sTBI) have difficulty knowing whether they are accurately expressing their thoughts and emotions because of ...