청소년 쥐에 대한 가벼운 외상성 뇌 손상의 소설 모델
Summary
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.
Abstract
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.
Introduction
중등도에서 중증 외상성 뇌 손상 (TBI), 거의 기술이 약한 유도하기 위해 개발되었습니다의 생성을위한 많은 널리 사용되는 방법이 있지만, 설치류에서 머리 부상을 마감했다. 경증 외상성 뇌 손상 (mTBI)가 세 배 더 일반적인 복합 1 중등도 뇌 손상보다 사실에 의해, mTBI의 안정적인 모델 연구에 대한 병태 생리, 신경 생물학 및 행동의 결과, 및 치료 전략을 용이하게하기 위해 필요하다. 예를 들어, 200 가지가 넘는다 지난 10 년간, 현재 동물 모델 2의 한계에 부분적으로는 TBI (3)의 치료를 위해 약물 임상 시험에 실패했습니다. 모델링 시스템이 병진 조사 연구를 위해 생성되는 경우, 결과의 적용 구현 모델의 유효성에 의존한다. mTBI / 뇌진탕의 연구를 위해 신뢰할 수있는 동물 모델은 생체 역학적 인 힘 respon을 모방하지 않을부상의 원인에 대한 sible뿐만 아니라 임상 적으로 인구에 의해보고 된 것과 일치 증상을 유발한다. 아이들이 mTBI에 특히 높은 위험이 있기 때문에 또한, 최적의 모델링 시스템은 성인 등가물뿐만 아니라, 젊은 청소년 설치류에 적용 할 수있다.
선수 mTBIs 또는 진탕 뇌 손상을 입었다 고하는 상황의 생체 역학적 분석은 부상의 가장 중요한 예측 요인 빠른 머리 가속 및 고속 영향 4 있음을 나타냅니다. 현재 TBI의 유도에 이용 설치류 모델의 대부분은 헤드 (5) (검토를 위해 2 참조)를 거의 또는 전혀 이동을 허용한다. 여기에 설명 된 모델은 피사체의 머리와 몸에 가속 / 감속의 힘을 적용 180 ° 회전 및 자유 낙하를 동반 물리적으로 억제되지 않은 청소년 쥐의 머리에 높은 속도에 미치는 영향을 제공합니다. 티여기에 mTBI의 유도에 대해이 수정 된 체중 감소 기술과 관련된 두 가지 주요 장점은. 첫째, 모델 (행동의 결과가 6 참조의 완전한 설명) 뇌에 대한 명백한 손상을 유발하지 않고 symptomology 같은 임상 적으로 진탕을 생산하고 있습니다. 후 진탕 증후군의 임상 보고서와도 일관성이 수정 체중 감소 기술은 이기종 결과를 생성합니다. mTBI의 효과가 중요하지만, 여러 결과 측정에 검사 할 때 mTBI을 경험 설치류 사이에 상당한 차이가 있습니다. 둘째, 본 방법은 반복 mTBI (7)의 조사를 허용한다. 기존 TBI 대부분 모델은 심각한 상해를 입힐 때, 그것은 전체 피질 광범위한 손상없이 반복적 TBI 공부 종종 초 부상을 충분히하는 것이 곤란하고, 거의 불가능하다.
따라서, 산업용 냉장고 변성 중량 드롭 기술을 이용하기위한 기본 원리mTBI의 ction의 더 밀접 청소년 인구의 병태 생리 및 뇌진탕의 symptomology 반복적 TBI를 나타내는 부상을 생산하는 것입니다. 특히 어린 시절 동안 증가 스포츠 관련 mTBI의 발생, 폭포, 자동차 사고로, mTBI의 독특한 설치류 모델은 쉽게 여러 히트에 적용 할 수 진탕 같은 뇌 손상의 연구를위한 유용한 도구와 연구자를 제공합니다 패러다임.
Protocol
Representative Results
Discussion
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’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.
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
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’s Hospital Foundation (ACHF) and the Alberta Children’s Hospital Research Institute (ACHRI). The Postdoctoral fellowship for RM was provided by ACHF.
Materials
| Brass Weights | Ginsberg Scientific | 7-2500-2 | Need to have metal loop attached to base |
| Alluminum Foil | Alcan | Available at most grocery stores | |
| Masking Tape | Commercially available | ||
| U-Shaped Plastic Stand | Constructed by Laboratory | ||
| Clamp Stand | Sigma-Aldrich | Z190357 | |
| Plastic Guide Tube | Could be constructed or purchased at a hardware store | ||
| Fishing Line | Angler 10lb | Purchased from a sporting goods retailer | |
| Isoflurane | Pharmaceutical Partners of Canada | DIN 02237518 | Inhalation Anesthetic |
| Topical Lidocaine (30ml) | Astra Zeneca | DIN 0001694 | Xylocaine Jelly 2% |
| Cotton Swabs | Commercially available | ||
| Heating Pad – 3 heat setting | Commercially available | ||
| Stop Watch | Sportline | L303 | Purchased from a sporting goods retailer |
| Video Camera | Sony | HDR-CX260V | |
| Sprague Dawley Rats | Charles River Laboratories | SAS SD 40 | Male and females ordered from Charles River Laboratories and pups bred in-house |
| Balance Beam | Constructed by Laboratory |
Riferimenti
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