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 os experimentos foram realizados de acordo com o Conselho Canadense de cuidados com animais e foram aprovados pela Universidade de Calgary, Comitê de Ética Animal Care. 1. Criação e Preparação animal <ol><li> Encomende ratas prenhes de fornecedores de animais de laboratório padrão ou filhotes da raça em casa de acordo com protocolos de reprodução padrão. </li><li> Casa todos os animais com acesso ad libitum a comida e água, em um rato quarto habitação temperatura controlada (21 ° C), que é mantido em uma luz 12:12 hr: ciclo escuro. </li><li> Quando os filhotes chegar dia pós-natal 21 (P21), desmamar filhotes de suas mães e casa em grupos do mesmo sexo de 3 ou 4. </li></ol> 2. Defina-up de Mild Traumatic Brain Injury (mTBI) Apparatus <ol><li> Antes do início do procedimento, pesos moinho para a massa desejado (por exemplo, 150 g). Fixe firmemente um anel de metal para a extremidade superior do peso permitindo que a linha de pesca para ser fifixada para o peso. </li><li> Pontuação folha de estanho com uma lâmina afiada. Certifique-se de que a folha de estanho teve suporta o peso do corpo do rato mas não irá interferir com a aceleração do rato após impacto da cabeça com o peso. </li><li> Fita da folha de estanho marcado para o estágio em forma de U feito de plástico transparente (38 x 27 x 27 cm3), que contém uma esponja de recolha (38 x 25 x 15 cm 3) (Figura 1), de modo que é esticada. </li><li> Coloque a fase de plástico em forma de U na posição correcta por baixo do tubo de guia feita de plástico transparente. </li><li> Segure o tubo guia de plástico (2,2 cm de diâmetro x 1,5 m) no lugar com um suporte de tripé e posicionar o tubo guia de modo que é de 3,5 cm acima da folha de estanho marcou. </li><li> Coloque a linha de pesca, através do anel de metal para assegurar que o peso da parte inferior do peso pendura livremente 2,5 centímetros acima da folha de estanho marcado. </li><li> Fixe firmemente a linha de pesca para o suporte de fixação. NOTA: Amarrar o peso para o clamp suporte a uma altura de 2,5 cm acima da folha de estanho evita re-hits enquanto o rato está caindo do impacto para a esponja de coleção). </li><li> Puxe o peso para cima através do tubo guia de plástico com a linha de pesca e mantê-lo no lugar com um pino de chave allen em 1,0 m. </li></ol> 3. Indução de mTBI <ol><li> Quando os ratos atingir P30 movimento gaiolas dentro da sala processual. </li><li> Coloque ratos em uma câmara de isoflurano e levemente anestesiar o rato até que ele não responde a uma pata ou cauda pitada. </li><li> Coloque rapidamente o rato peito para baixo sobre o papel alumínio marcou com a cabeça diretamente no caminho do peso cair. Veja a Figura 2. Se o rato começa a se mover ou wake-up antes de poder ser colocado no papel alumínio marcou, voltar para a câmara de isoflurano até que não responde a uma pata ou cauda pitada e começar de novo. </li><li> Puxe o pino chave Allen, permitindo que o peso a cair verticalmente através do tubo guia de plástico e bata no rato na cabeça. The rato serão submetidos a uma rápida rotação e terra 180 ° na posição supina. </li><li> Remover imediatamente o rato a partir da esponja coleção e aplicar lidocaína tópica para a cabeça do rato com um aplicador de algodão Pontas. </li><li> Coloque o rato em decúbito dorsal em uma gaiola limpa, que é aquecida por defini-lo em cima de uma almofada de aquecimento disponíveis comercialmente. </li><li> Usando um cronômetro ou timer digital adquirir o &quot;time-to-right&quot;. Tempo para a direita é o tempo que o rato para acordar da anestesia e virar a partir da posição deitada para a posição prona ou comece a caminhar. </li><li> Retorne o rato para sua gaiola de casa depois de ter recuperado o comportamento normal (aparência, andar, explorar, etc.). </li><li> Repita os passos de 3,2-3,8 para cada rato adicional exigindo uma mTBI. </li><li> Repita o procedimento no mesmo rato em vários pontos de tempo para experiências MTBI repetitivas. </li></ol> 4. A indução da lesão Sham <ol><li> Levemente Anesthetize o rato com isoflurano até que ele não responde a uma pata ou cauda pitada. </li><li> Coloque rapidamente o rato peito para baixo sobre o papel alumínio marcou com a cabeça diretamente no caminho do peso cair. </li><li> Retire o rato da folha de estanho sem puxar o pino de chave allen do tubo guia de plástico e aplique lidocaína tópica para a cabeça do rato com um aplicador de algodão Pontas. </li><li> Coloque o rato em decúbito dorsal em uma gaiola limpa, que é aquecida por defini-lo em cima de uma almofada de aquecimento disponíveis comercialmente. </li><li> Use um cronômetro ou timer digital para adquirir o &quot;time-to-right&quot;. </li><li> Retorne o rato para sua gaiola de casa depois de ter recuperado o comportamento normal (aparência, andar, explorar, etc.). </li></ol> 5. Verificação de mTBI com o teste de caminhada de feixe 8 <ol><li> 24 h após a indução do mTBI ou animais sham lesão de retorno para o quarto processual. </li><li> Transfira os ratos a uma gaiola exploração limpoe colocá-home-gaiola do rato na extremidade mais estreita dos 165 centímetros afuniladas feixe de modo que a parte aberta da gaiola de casa enfrenta a extremidade mais estreita do feixe. NOTA: O feixe cônico é de 165 cm de comprimento. A plataforma central do feixe tem uma largura de 6 cm na extremidade larga e 1,75 cm na parte mais estreita. O feixe de centro tem bordas (2 cm de largura e 2 cm abaixo da viga central) que fornecem segurança quando deslizamentos pé do rato. Coloque enchimento de espuma abaixo do feixe para reduzir o risco de lesões nos ratos que podem cair fora do feixe durante o teste. </li><li> Coloque uma câmara de vídeo na ponta mais larga do feixe e da posição afunilada / aumentar a câmara de vídeo para assegurar que o investigador observar o vídeo pode ver claramente os movimentos do rato por todo o comprimento da viga afunilada. </li><li> Coloque o rato na grande final do feixe cônico e incentivá-la a atravessar o feixe de sua gaiola de casa. Quando o rato cruza o feixe cônico, deixar o rato em sua gaiola de casa por pelo menos 60 segundos para reinForce o local de destino. Esta experimentação é # 1 e não incluídos na análise. </li><li> Ligue a câmera de vídeo e permitir que o rato para concluir a tarefa feixe-walking 4 vezes adicionais (mantendo os períodos de reforço 60 seg na gaiola). Uma vez que o rato tenha completado todos os ensaios, o retorno do rato para sua gaiola de casa. </li><li> Para marcar, registrar o número de perna-pé deslizamentos traseiras que ocorrem eo tempo / duração para atravessar o feixe, para cada prova individual. Use esses dados para calcular o número médio de pernas traseiras pé-deslizamentos e tempo para atravessar o feixe para cada rato. </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.

Embora existam muitos métodos amplamente utilizados para a geração de moderada a grave lesão traumática do cérebro (TBI), muito poucas técnicas foram desenvolvidas para induzir leve, fechado ferimentos na cabeça em roedores. Devido ao fato de que leve traumatismo cranioencefálico (mTBI) é três vezes mais comum do que a lesão cerebral moderada e grave combinado 1, é necessário um modelo confiável de mTBI para facilitar a investigação sobre fisiopatologia, os resultados neurobiológicos e comportamentais, e estratégias terapêuticas. Por exemplo, em parte devido às limitações dos modelos animais atuais 2, na última década, houve mais de 200 falhou ensaios clínicos de medicamentos para o tratamento de TBI 3. Quando os sistemas de modelagem são gerados para estudos de investigação de translação, a aplicabilidade dos resultados dependem da validade do modelo implementado. Para o estudo da mTBI / concussão, um modelo animal de confiança não apenas imitar a biomecânica forças responsável pela etiologia da lesão, mas também induzir sintomas consistentes com os relatados pela população clinicamente relevante. Além disso, porque as crianças estão em risco particularmente elevado para mTBI, sistemas de modelagem óptimos seria aplicável aos roedores jovens e jovens, em adição aos seus equivalentes adultos. Análises biomecânicas das circunstâncias em que os atletas sofreram mTBIs ou lesões cerebrais concussivas indicam que os fatores preditivos mais críticos para lesão são aceleração cabeça rápido e impactos de alta velocidade 4. A maioria dos modelos de roedores actualmente utilizados para a indução de TCE permitir pouco ou nenhum movimento da cabeça 5 (para revisão ver 2). O modelo descrito aqui, proporciona um impacto de alta velocidade para a cabeça de um rato juvenil fisicamente desenfreada que é acompanhada por uma rotação de 180 ° e de queda livre que se aplica forças de aceleração / desaceleração de cabeça e no corpo do sujeito. Taqui são dois principais vantagens associadas a esta técnica de queda de peso modificado para a indução de mTBI. Primeiro, o modelo produz concussiva clinicamente relevante como sintomatologia sem causar qualquer dano evidente para o cérebro (para uma descrição completa de resultados comportamentais ver 6). Também consistente com os relatórios clínicos da síndrome pós-concussão, esta técnica peso-drop modificado produz resultados heterogêneos. Embora os efeitos da mTBI são significativos, há uma variação substancial entre os roedores que passaram por um mTBI quando examinado em várias medidas de resultado. Em segundo lugar, o método permite o estudo de 7 mTBI repetitivo. Como a maioria dos modelos de TCE existentes provocado tais ferimentos graves, muitas vezes é difícil para induzir uma segunda lesão, e quase impossível estudar TBI repetitivo, sem grandes danos a todo o córtex. Portanto, a razão primária para a utilização da técnica de queda de peso modificado para a inducção de mTBI é produzir uma lesão que representa mais de perto a fisiopatologia e sintomatologia de concussão e repetitivo TBI nas populações juvenis. Com o aumento da incidência de mTBI relacionado a esportes, quedas e acidentes automobilísticos, especialmente durante a infância, este modelo de roedor única de mTBI fornece aos pesquisadores uma ferramenta valiosa para o estudo de concussão-like lesão cerebral que pode ser facilmente aplicada a multiple-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.

A técnica de peso-gota modificado descrito acima é um método fiável para a indução de uma lesão cerebral traumática leve (mTBI) em ratos juvenis. Utilizando um peso impacto de 150 g, esta técnica tem sido aplicada com sucesso em ratos jovens que vão 50-120 g. Além disso, o procedimento pode ser facilmente repetido nos mesmos animais para o estudo de mTBI repetitivo. Embora os animais que passam por uma única exposição mTBI um aumento do tempo para a direita (Figura 3) e aparecem surpreendeu ao acordar, eles rapidamente retomar suas atividades normais e são visualmente indistinguíveis de animais feridos por simulação. Tendo em conta que a lesão é leve, lidocaína tópica que elimina qualquer dor associada com o impacto de olhar, é o único analgésico necessário. Isso é importante para a investigação como medicamentos para a dor são conhecidos por interferir com os processos inflamatórios e recuperação típicas. Devido à falta de sintomatologia evidente, a tarefa é um feixe de passeio fiável paraol que pode ser utilizado para validar a indução da mTBI. É importante notar, que nem todos os animais que experimentam uma mTBI exibirão défices na tarefa viga curta, mas como um grupo, os ratos juvenis com uma mTBI demonstrar significativamente mais traseiras da perna do pé-deslizamentos quando em comparação com ratos jovens com uma lesão simulada (Figura 4). Outra característica chave desta técnica peso-gota modificado é a falta de contenção aplicada ao rato juvenil durante a indução da lesão. Ao entregar um golpe de raspão na cabeça seguido de rápida aceleração e desaceleração de rotação, este modelo representa mais de perto as forças biomecânicas atribuídos a mTBI e concussão. Quando este procedimento é aplicado a ratos jovens ou ratos adultos, as taxas de mortalidade são extremamente baixos (7/202 animais juvenis ~ taxa de mortalidade de 3,4%), e fratura de crânio e hemorragia intracraniana são excepcionalmente raros 6,7. Além disso, o modelo produz sy clinicamente relevantemptomology. Roedores jovens que experimentaram um único mTBI demonstrou déficits de equilíbrio e motor comportamentos, juntamente com déficits de função executiva, o aumento de comportamentos de tipo depressivo, e interações sociais alterados 6,9. Da mesma forma, camundongos adultos também apresentam equilíbrio e coordenação déficits leves que recuperar com o tempo 7. Finalmente, a indução de mTBI usando este modelo requer anestesia mínima e não envolve preparação cirúrgica ou se esconder debaixo do crânio. Os resultados, portanto, não são distorcidos por efeitos inflamatórios ou imunológicos confusão desencadeada pela cirurgia ou anestesia. Além disso, o tempo de recuperação rápida e falta de feridas abertas permite o início de paradigmas de ensaio adicionais para ocorrer pouco depois de experimentar o mTBI roedores. <img alt="Figura 1" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig1highres.jpg" width="500" /> Figura 1: </strong<html> &gt; C artoon representação da forma de U fase de plástico e esponja de recolha com todas as dimensões relevantes. Uma distância de 10 cm deve ser mantida entre a esponja de recolha e o início da fase de plástico para assegurar o rato juvenil tem tempo suficiente para completar os 180 rotação °. <img alt="Figura 2" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig2highres.jpg" width="500" /> Figura 2: (A) representação fotográfica da plataforma a indução da lesão. O rato juvenil é colocado no peito para baixo sobre o papel alumínio marcou de modo que a cabeça está diretamente abaixo do peso em queda. (B) Vista lateral da plataforma de indução da lesão. (C) demonstração fotográfica do peso usado na indução do mTBI . fazer upload / 51820 / 51820fig3highres.jpg &quot;width =&quot; 500 &quot;/&gt; Figura 3: Representação gráfica das diferenças médias de tempo para a direita entre ratos jovens que experimentaram um único mTBI e ratos jovens que sofreram uma lesão sham (* p &lt;0,01) Os ratos que receberam uma exposição mTBI um aumento significativo no. duração de tempo necessária para endireitar-se a partir da posição supina. <img alt="Figura 4" fo:content-width="5in" src="/files/ftp_upload/51820/51820fig4highres.jpg" width="500" /> Figura 4: Representação gráfica do número médio de perna-pé deslizamentos traseiras expostas na tarefa Walking Beam por ratos jovens que experimentaram um único mTBI e ratos jovens que sofreram uma lesão sham (* 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.

Um novo modelo de Mild Traumatic Brain Injury para ratos jovens

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

a-novel-model-of-mild-traumatic-brain-injury-for-juvenile-rats

Research

JoVE Journal

Medicine

23.4K visualizações.  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. 

Vídeo: 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 e crônica teste sensorial tátil após a lesão medular em ratos

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

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.

Um modelo de contusão grave de lesão medular em ratos

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.

Um método de estabilização Novel Vertebral para a Produção de contusão Lesão Medular

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.

Estique em células cerebrais endoteliais microvasculares (cEnd) como um<em&gt; In Vitro</em&gt; Modelo de lesão cerebral traumática do cérebro Barreira Hemato

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 Impact Cortical para lesão 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.

Renal Isquemia Reperfusão: um modelo do rato de lesão e regeneração

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.

Um Modelo de Lesão Medular Contusiva Baseado em Cilindrada de Tecidos em Ratos

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.

Um modelo de mouse de lesões cerebrais traumáticas leves simples e repetitivas

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.

Hemiseção Lateral da Medula Espinhal e Avaliações Comportamentais Assimétricas em Ratos Adultos

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.

Avaliação semi-quantitativa usando [18F] FDG Tracer em pacientes com lesão cerebral grave

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