Acute histopathological responses and long-term behavioral outcomes in mice with graded controlled cortical impact injury

While animal models of controlled cortical impact often display short-term motor dysfunction after injury, histological examinations do not show severe cortical damage. Thus, this model requires further improvement. Mice were subjected to injury at three severities using a Pin-Point^(TM)-controlled cortical impact device to establish secondary brain injury mouse models. Twenty-four hours after injury, hematoxylin-eosin staining, Fluoro-Jade B histofluorescence, and immunohistochemistry were performed for brain slices. Compared to the uninjured side, we observed differences of histopathological findings, neuronal degeneration, and glial cell number in the CA2 and CA3 regions of the hippocampus on the injured side. The Morris water maze task and beam-walking test verified long-term(14–28 days) spatial learning/memory and motor balance. To conclude, the histopathological responses were positively correlated with the degree of damage,as were the long-term behavioral manifestations after controlled cortical impact. All animal procedures were approved by the Institutional Animal Care and Use Committee at Shanghai Jiao Tong University School of Medicine.

Endorepellin downregulation promotes angiogenesis after experimental traumatic brain injury

Endorepellin plays a key role in the regulation of angiogenesis,but its effects on angiogenesis after traumatic brain injury are unclear.This study explored the effects of endorepellin on angiogenesis and neurobehavioral outcomes after traumatic brain injury in mice.Mice were randomly divided into four groups:sham,controlled cortical impact only,adeno-associated virus(AAV)-green fluorescent protein,and AAV-shEndorepellin-green fluorescent protein groups.In the controlled cortical impact model,the transduction of AAV-shEndorepellin-green fluorescent protein downregulated endorepellin while increasing the number of CD31+/Ki-67+proliferating endothelial cells and the functional microvessel density in mouse brain.These changes resulted in improved neurological function compared with controlled cortical impact mice.Western blotting revealed increased expression of vascular endothelial growth factor and angiopoietin-1 in mice treated with AAV-shEndorepellin-green fluorescent protein.Synchrotron radiation angiography showed that endorepellin downregulation promoted angiogenesis and increased cortical neovascularization,which may further improve neurobehavioral outcomes.Furthermore,an in vitro study showed that downregulation of endorepellin increased tube formation by human umbilical vein endothelial cells compared with a control.Mechanistic analysis found that endorepellin downregulation may mediate angiogenesis by activating vascular endothelial growth factor-and angiopoietin-1-related signaling pathways.

The pig as a preclinical traumatic brain injury model:current models,functional outcome measures,and translational detection strategies

Traumatic brain injury(TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the development of functional impairments. However, there are currently no effective therapeutic interventions that improve brain outcomes following TBI. As a result, a number of experimental TBI models have been developed to recapitulate TBI injury mechanisms and to test the efficacy of potential therapeutics. The pig model has recently come to the forefront as the pig brain is closer in size, structure, and composition to the human brain compared to traditional rodent models, making it an ideal large animal model to study TBI pathophysiology and functional outcomes. This review will focus on the shared characteristics between humans and pigs that make them ideal for modeling TBI and will review the three most common pig TBI models–the diffuse axonal injury, the controlled cortical impact, and the fluid percussion models. It will also review current advances in functional outcome assessment measures and other non-invasive, translational TBI detection and measurement tools like biomarker analysis and magnetic resonance imaging. The use of pigs as TBI models and the continued development and improvement of translational assessment modalities have made significant contributions to unraveling the complex cascade of TBI sequela and provide an important means to study potential clinically relevant therapeutic interventions.

Does progesterone show neuroprotective effects on traumatic brain injury through increasing phosphorylation of Akt in the hippocampus?

There are currently no federally approved neuroprotective agents to treat traumatic brain injury. Progesterone, a hydrophobic steroid hormone, has been shown in recent studies to exhibit neu-roprotective effects in controlled cortical impact rat models. Akt is a protein kinase known to play a role in cell signaling pathways that reduce edema, inlfammation, apoptosis, and promote cell growth in the brain. This study aims to determine if progesterone modulates the phosphor-ylation of Aktvia its threonine 308 phosphorylation site. Phosphorylation at the threonine 308 site is one of several sites responsible for activating Akt and enabling the protein kinase to carry out its neuroprotective effects. To assess the effects of progesterone on Akt phosphorylation, C57BL/6 mice were treated with progesterone （8 mg/kg） at 1 （intraperitonally）, 6, 24, and 48 hours （subcutaneously） post closed-skull traumatic brain injury. The hippocampus was harvest-ed at 72 hours post injury and prepared for western blot analysis. Traumatic brain injury caused a signiifcant decrease in Akt phosphorylation compared to sham operation. However, mice treat-ed with progesterone following traumatic brain injury had an increase in phosphorylation of Akt compared to traumatic brain injury vehicle. Our ifndings suggest that progesterone is a viable treatment option for activating neuroprotective pathways after traumatic brain injury.

Differences in pathological changes between two rat models of severe traumatic brain injury

The rat high-impact free weight drop model mimics the diffuse axonal injury caused by severe traumatic brain injury in humans,while severe controlled cortical impact can produce a severe traumatic brain injury model using precise strike parameters.In this study,we compare the pathological mechanisms and pathological changes between two rat severe brain injury models to identify the similarities and differences.The severe controlled cortical impact model was produced by an electronic controlled cortical impact device,while the severe free weight drop model was produced by dropping a 500 g free weight from a height of 1.8 m through a plastic tube.Body temperature and mortality were recorded,and neurological deficits were assessed with the modified neurological severity score.Brain edema and bloodbrain barrier damage were evaluated by assessing brain water content and Evans blue extravasation.In addition,a cytokine array kit was used to detect inflammatory cytokines.Neuronal apoptosis in the brain and brainstem was quantified by immunofluorescence staining.Both the severe controlled cortical impact and severe free weight drop models exhibited significant neurological impairments and body temperature fluctuations.More severe motor dysfunction was observed in the severe controlled cortical impact model,while more severe cognitive dysfunction was observed in the severe free weight drop model.Brain edema,inflammatory cytokine changes and cortical neuronal apoptosis were more substantial and blood-brain barrier damage was more focal in the severe controlled cortical impact group compared with the severe free weight drop group.The severe free weight drop model presented with more significant apoptosis in the brainstem and diffused blood-brain barrier damage,with higher mortality and lower repeatability compared with the severe controlled cortical impact group.Severe brainstem damage was not found in the severe controlled cortical impact model.These results indicate that the severe controlled cortical impact model is relatively more stable,more reproducible,and shows obvious cerebral pathological changes at an earlier stage.Therefore,the severe controlled cortical impact model is likely more suitable for studies on severe focal traumatic brain injury,while the severe free weight drop model may be more apt for studies on diffuse axonal injury.All experimental procedures were approved by the Ethics Committee of Animal Experiments of Tianjin Medical University,China(approval No.IRB2012-028-02)in Febru ary 2012.

Urolithin A alleviates blood-brain barrier disruption and attenuates neuronal apoptosis following traumatic brain injury in mice

Urolithin A(UA)is a natural metabolite produced from polyphenolics in foods such as pomegranates,berries,and nuts.UA is neuroprotective against Parkinson’s disease,Alzheimer’s disease,and cerebral hemorrhage.However,its effect against traumatic brain injury remains unknown.In this study,we established adult C57BL/6J mouse models of traumatic brain injury by controlled cortical impact and then intraperitoneally administered UA.We found that UA greatly reduced brain edema;increased the expression of tight junction proteins in injured cortex;increased the immunopositivity of two neuronal autophagy markers,microtubule-associated protein 1A/B light chain 3A/B(LC3)and p62;downregulated protein kinase B(Akt)and mammalian target of rapamycin(mTOR),two regulators of the phosphatidylinositol 3-kinase(PI3K)/Akt/mTOR signaling pathway;decreased the phosphorylation levels of inhibitor of NFκB(IκB)kinase alpha(IKKα)and nuclear factor kappa B(NFκB),two regulators of the neuroinflammation-related Akt/IKK/NFκB signaling pathway;reduced blood-brain barrier permeability and neuronal apoptosis in injured cortex;and improved mouse neurological function.These findings suggest that UA may be a candidate drug for the treatment of traumatic brain injury,and its neuroprotective effects may be mediated by inhibition of the PI3K/Akt/mTOR and Akt/IKK/NFκB signaling pathways,thus reducing neuroinflammation and enhancing autophagy.

Essential role of MALAT1 in reducing traumatic brain injury

As a highly evolutionary conserved long non-coding RNA,metastasis associated lung adenocarcinoma transcript 1(MALAT1)was first demonstrated to be related to lung tumor metastasis by promoting angiogenesis.To investigate the role of MALAT1 in traumatic brain injury,we established mouse models of controlled cortical impact and cell models of oxygen-glucose deprivation to mimic traumatic brain injury in vitro and in vivo.The results revealed that MALAT1 silencing in vitro inhibited endothelial cell viability and tube formation but increased migration.In MALAT1-deficient mice,endothelial cell proliferation in the injured cortex,functional vessel density and cerebral blood flow were reduced.Bioinformatic analyses and RNA pull-down assays validated enhancer of zeste homolog 2(EZH2)as a downstream factor of MALAT1 in endothelial cells.Jagged-1,the Notch homolog 1(NOTCH1)agonist,reversed the MALAT1 deficiency-mediated impairment of angiogenesis.Taken together,our results suggest that MALAT1 controls the key processes of angiogenesis following traumatic brain injury in an EZH2/NOTCH1-dependent manner.

Automated monitoring of early neurobehavioral changes in mice following traumatic brain injury

Traumatic brain injury often causes a variety of behavioral and emotional impairments that can develop into chronic disorders. Therefore, there is a need to shift towards identifying early symptoms that can aid in the prediction of traumatic brain injury outcomes and behavioral endpoints in patients with traumatic brain injury after early interventions. In this study, we used the Smart Cage system, an automated quantitative approach to assess behavior alterations in mice during an early phase of traumatic brain injury in their home cages. Female C57BL/6 adult mice were subjected to moderate controlled cortical impact（CCI） injury. The mice then received a battery of behavioral assessments including neurological score, locomotor activity, sleep/wake states, and anxiety-like behaviors on days 1, 2, and 7 after CCI. Histological analysis was performed on day 7 after the last assessment. Spontaneous activities on days 1 and 2 after injury were significantly decreased in the CCI group. The average percentage of sleep time spent in both dark and light cycles were significantly higher in the CCI group than in the sham group. For anxiety-like behaviors, the time spent in a light compartment and the number of transitions between the dark/light compartments were all significantly reduced in the CCI group than in the sham group. In addition, the mice suffering from CCI exhibited a preference of staying in the dark compartment of a dark/light cage. The CCI mice showed reduced neurological score and histological abnormalities, which are well correlated to the automated behavioral assessments. Our findings demonstrate that the automated Smart Cage system provides sensitive and objective measures for early behavior changes in mice following traumatic brain injury.

Identification of predictive MRI and functional biomarkers in a pediatric piglet traumatic brain injury model

Traumatic brain injury(TBI) at a young age can lead to the development of long-term functional impairments. Severity of injury is well demonstrated to have a strong influence on the extent of functional impairments;however, identification of specific magnetic resonance imaging(MRI) biomarkers that are most reflective of injury severity and functional prognosis remain elusive. Therefore, the objective of this study was to utilize advanced statistical approaches to identify clinically relevant MRI biomarkers and predict functional outcomes using MRI metrics in a translational large animal piglet TBI model. TBI was induced via controlled cortical impact and multiparametric MRI was performed at 24 hours and 12 weeks post-TBI using T1-weighted, T2-weighted, T2-weighted fluid attenuated inversion recovery, diffusion-weighted imaging, and diffusion tensor imaging. Changes in spatiotemporal gait parameters were also assessed using an automated gait mat at 24 hours and 12 weeks post-TBI. Principal component analysis was performed to determine the MRI metrics and spatiotemporal gait parameters that explain the largest sources of variation within the datasets. We found that linear combinations of lesion size and midline shift acquired using T2-weighted imaging explained most of the variability of the data at both 24 hours and 12 weeks post-TBI. In addition, linear combinations of velocity, cadence, and stride length were found to explain most of the gait data variability at 24 hours and 12 weeks post-TBI. Linear regression analysis was performed to determine if MRI metrics are predictive of changes in gait. We found that both lesion size and midline shift are significantly correlated with decreases in stride and step length. These results from this study provide an important first step at identifying relevant MRI and functional biomarkers that are predictive of functional outcomes in a clinically relevant piglet TBI model. This study was approved by the University of Georgia Institutional Animal Care and Use Committee(AUP: A2015 11-001) on December 22, 2015.

Temporal changes in inflammatory mitochondria-enriched microRNAs following traumatic brain injury and effects of miR-146a nanoparticle delivery

MicroRNAs(miRNAs)are small non-coding RNA molecules that regulate post-transcriptional gene expression and contribute to all aspects of cellular function.We previously reported that the activities of several mitochondria-enriched miRNAs regulating inflammation(i.e.,miR-142-3p,miR-142-5p,and miR-146a)are altered in the hippocampus at 3–12 hours following a severe traumatic brain injury.In the present study,we investigated the temporal expression profile of these inflammatory miRNAs in mitochondria and cytosol fractions at more chronic post-injury times following severe controlled cortical impact injury in rats.In addition,several inflammatory genes were analyzed in the cytosol fractions.The analysis showed that while elevated levels were observed in cytoplasm,the mitochondria-enriched miRNAs,miR-142-3p and miR-142-5p continued to be significantly reduced in mitochondria from injured hippocampi for at least 3 days and returned to near normal levels at 7 days post-injury.Although not statistically significant,miR-146a also remained at reduced levels for up to 3 days following controlled cortical impact injury,and recovered by 7 days.In contrast,miRNAs that are not enriched in mitochondria,including miR-124a,miR-150,miR-19b,miR-155,and miR-223 were either increased or demonstrated no change in their levels in mitochondrial fractions for 7 days.The one exception was that miR-223 levels were reduced in mitochondria at 1 day following injury.No major alterations were observed in sham operated animals.This temporal pattern was unique to mitochondria-enriched miRNAs and correlated with injury-induced changes in mitochondrial bioenergetics as well as expression levels of several inflammatory markers.These observations suggested a potential compartmental re-distribution of the mitochondria-enriched inflammatory miRNAs and may reflect an intracellular mechanism by which specific miRNAs regulate injury-induced inflammatory signaling.To test this,we utilized a novel peptide-based nanoparticle strategy for in vitro and in vivo delivery of a miR-146a mimic as a potential therapeutic strategy for targeting nuclear factor-kappa B inflammatory modulators in the injured brain.Nanoparticle delivery of miR-146a to BV-2 or SH-SY5Y cells significantly reduced expression of TNF receptor-associated factor 6(TRAF6)and interleukin-1 receptor-associated kinase 1(IRAK1),two important modulators of the nuclear factor-kappa B(NF-κB)pro-inflammatory pathway.Moreover,injections of miR-146a containing nanoparticles into the brain immediately following controlled cortical impact injury significantly reduced hippocampal TNF receptor-associated factor 6 and interleukin-1 receptor-associated kinase 1 levels.Taken together,our studies demonstrate the subcellular alteration of inflammatory miRNAs after traumatic brain injury and establish proof of principle that nanoparticle delivery of miR-146a has therapeutic potential for modulating pro-inflammatory effectors in the injured brain.All of the studies performed were approved by the University of Kentucky Institutional Animal Care and Usage Committee(IACUC protocol#2014-1300)on August 17,2017.

Acute effects of human protein S administration after traumatic brain injury in mice

Despite years of effort,no effective acute phase treatment has been discovered for traumatic brain injury.One impediment to successful drug development is entangled secondary injury pathways.Here we show that protein S,a natural multifunctional protein that regulates coagulation,inflammation,and apoptosis,is able to reduce the extent of multiple secondary injuries in traumatic brain injury,and therefore improve prognosis.Mice subjected to controlled cortical impact were treated acutely(10–15 minutes post-injury)with a single dose of either protein S(1 mg/kg)or vehicle phosphate buffered saline via intravenous injection.At 24 hours post-injury,compared to the non-treated group,the protein S treated group showed substantial improvement of edema and fine motor coordination,as well as mitigation of progressive tissue loss.Immunohistochemistry and western blot targeting caspase-3,B-cell lymphoma 2(Bcl-2)along with terminal deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)assay revealed that apoptosis was suppressed in treated animals.Immunohistochemistry targeting CD11 b showed limited leukocyte infiltration in the protein S-treated group.Moreover,protein S treatment increased the ipsilesional expression of aquaporin-4,which may be the underlying mechanism of its function in reducing edema.These results indicate that immediate intravenous protein S treatment after controlled cortical impact is beneficial to traumatic brain injury prognosis.Animal Use Protocols(AUPs)were approved by the University Committee on Animal Resources(UCAR)of University of Rochester Medical Center(approval No.UCAR-2008-102 R)on November 12,2013.

跑台训练促进可控性皮质损伤大鼠髓鞘再生

目的:研究跑台训练对可控性皮质损伤(CCI)大鼠髓鞘再生的影响。方法:通过撞击法制备CCI大鼠模型,进行8周跑台训练,采用改良的神经功能严重程度评分法检测神经功能缺损,利用平衡木实验检测大鼠的运动功能,使用酶联免疫吸附试验(ELISA)和RT-qPCR方法检测运动皮质中(BDNF)的表达,利用Western Blot方法检测胼胝体中髓鞘碱性蛋白(MBP)、髓鞘少突胶质细胞糖化蛋白(MOG)和髓鞘蛋白脂蛋白(PLP)的表达。结果:跑台训练改善了CCI损伤大鼠的神经功能评分和运动功能,增加了运动皮质中BDNF的表达,同时MBP、MOG和PLP表达上调。结论:跑台训练通过上调BDNF促进髓鞘修复,从而改善CCI损伤引起的神经功能缺损。

小鼠控制性脑皮质撞击模型的构建及分级

目的建立小鼠控制性脑皮质撞击模型,并对损伤程度进行分级,为探索小鼠颅脑创伤的病理生理机制和治疗方法创造条件。方法雄性C57BL/6J小鼠24只,分为4组(实验组3组,对照组1组),每组随机分配6只动物,应用PinPointTMPCI3000精细颅脑撞击仪,设定不同的打击参数,精确撞击小鼠脑皮质。其中,实验组打击深度分别为0.5 mm、1.0 mm、1.5 mm;打击时间均为80 ms;打击速度均为1.5 m/s。对照组只开骨窗,不打击脑皮质。致伤后观察小鼠意识和神经反射的抑制时间。伤后24h处死小鼠,取脑组织行HE染色,Fluoro-Jade B组织荧光染色。观察小鼠脑组织损伤侧海马CA3区退变神经元数目的变化。结果小鼠的脑损伤程度和打击强度相关;打击深度为0.5mm时模拟轻度颅脑损伤;打击深度为1.0 mm时模拟中度颅脑损伤;打击深度为1.5 mm时模拟重度颅脑损伤。结论应用PinPointTMPCI3000精细颅脑撞击仪成功创建出小鼠控制性脑皮质撞击模型,并且给予轻度、中度、重度损伤分级,为进一步研究颅脑创伤病理生理机制和治疗方法创造条件。

一种模拟大鼠不同程度颅脑损伤模型的构建与评估

目的构建并评估可以模拟不同损伤程度的大鼠颅脑损伤模型。方法将12只大鼠随机分为3组(轻、中、重度颅脑损伤组),以可控性颅脑损伤模型为基础,不同组采用特定致伤参数(探头致伤深度:轻度为2~3 mm,中度为3~4 mm,重度为4~5 mm;致伤速度均为2.5 m/s,致伤时间为0.1 s),造成不同程度颅脑损伤。分别采用MRI、行为学定量评价,颅脑病理定性分析,评估颅脑损伤程度。结果损伤后大鼠均出现不同程度行为异常,损伤颅脑病理显示组织神经元减少,小胶质细胞浸润,不同程度充血、水肿,轻度颅脑损伤组损伤体积(11.33±1.11)mm^3,中度颅脑损伤组损伤体积(20.77±1.90)mm^3,重度颅脑损伤组损伤体积(46.19±12.79)mm^3。结论采用可控性颅脑损伤方法可构建具有良好重复性、可靠性、稳定性的大鼠颅脑损伤模型,多种方式定量评估损伤程度相对精确,为后续研究奠定了基础。

脑损伤动物模型研究：液压冲击损伤与控制性皮层撞击损伤的比较

目的对两种常见的脑损伤动物模型即液压冲击损伤（FPI）模型与控制性皮层撞击（CCI）模型进行比较，评价两种脑损伤动物模型特点，为脑损伤动物模型的实验研究提供指导性意见。方法将140只大鼠分成7组，分别制作FPI模型（分别以0．1、0．2、0-3MPa三种不同冲击压力，每组20只）和CCI模型（分别以1．5、2．5、3．5mm三种不同撞击深度，每组20只），以假损伤组（Sham组20只）作为对照组。24h内比较其死亡率，观察其伤后生命体征（呼吸、血压、心跳）的变化，进行神经功能缺失评分，24h后处死大鼠取脑组织进行组织形态学评价。结果FPI模型冲击压力达到0．3MPa时，CCI模型撞击深度达到3．5mm时，死亡率均明显升高；FPI模型和CCI模型均出现不同程度的生命体征变化和神经功能的缺失，且随着冲击压力和撞击深度的增加，其生命体征评分和神经功能缺失评分均呈梯度上升：FPI模型和CCI模型两组脑组织均出现明显的脑损伤形态学改变。FPI模型和CCI模型之间比较，其死亡率、生命体征评分、神经功能缺失评分及脑组织形态学变化均无明显差异。结论采用合适的冲击压力（0．2MPa）、撞击深度（2．5mm）、撞击速度（2m／s）和接触时间（85ms），液压冲击损伤（FPI）与控制性皮层撞击（CCI）这两种方法均可制作可靠的急性脑损伤动物模型。

脑皮质撞击法致创伤性脑损伤大鼠模型的构建

目的通过脑皮质撞击法构建不同损伤程度创伤性脑损伤大鼠模型,以探讨脑皮质撞击仪参数的选取,为创伤性脑损伤的研究提供实验基础。方法雌性SD大鼠48只,随机等分为6组:即T1模型组、T2模型组、T3模型组、T4模型组、T5模型组(打击深度分别为1、2、3、4、5 mm)和正常对照组。模型组应用皮质和打击仪,通过设定共同的打击速率(5 m/s)、共同的打击最低点持续时间(200 ms)和不同的打击深度,造成不同程度的创伤性脑损伤,对照组不进行任何操作。术后24 h进行神经功能损伤评分(m NSS)、网屏实验评分和旷场试验评分。结果各TBI模型组的m NSS评分与对照组比较,差异均有统计学意义(P均<0.05),随着打击深度的增加,评分依次增高,但T1组与T2组差异无统计学意义(P<0.05);T2组、T3组、T4组和T5组的网屏实验评分与对照组比较,差异均有统计学意义(P<0.05);旷场试验中,各TBI模型组仅T3组垂直得分与对照组比较,差异有统计学意义(P<0.05)。水平得分和大便粒数两项指标,各组差异均无统计学意义(P>0.05)。结论以5 m/s为打击速率,200 ms为打击最低点持续时间,打击深度分别为1、3、4 mm可有效构建模拟轻、中、重度创伤性脑损伤的大鼠模型。

大鼠局灶性脑挫裂伤不同损伤区域水通道蛋白4表达变化的实验研究

目的探索水孔通道蛋白4(AQP4)在局灶性脑挫裂伤(CCII)不同损伤区域表达变化,及其对创伤性脑水肿血脑屏障(BBB)的影响。方法雄性成年Wistar大鼠,随机分为假手术组和CCII组,其中CCII组分为损伤中心组和损伤外周组。参照改良Feeney’s自由落体硬膜外撞击法制作CCII模型。结果损伤中心组和损伤周围组脑组织含水量明显高于假手术组;免疫组织化学结果显示损伤中心组在各检测时间点的AQP4含量和伊文思蓝(EB)含量均明显高于假手术组和损伤周围组,差异有统计学意义(P<0.05)。结论 CCII后AQP4蛋白的表达变化趋势和BBB的通透性相一致;损伤中心AQP4含量与损伤周围AQP4含量存在差异,这与相应区域的脑组织水肿类型相关。脑挫裂伤外周水肿带AQP4含量是降低的,损伤中心部位AQP4含量是升高的。损伤中心以血管源性脑水肿为主,脑挫裂伤外周水肿带以细胞毒性脑水肿为主。

门冬氨酸钾减轻大鼠可控性皮质打击伤引起的脑损伤

目的门冬氨酸钾(potassium aspartate,PA)作为一种电解质补充剂,在临床上广泛使用。以往的研究发现门冬氨酸钾在脑缺血/再灌注大鼠中对细胞凋亡有神经保护的作用。本研究将探讨门冬氨酸钾对创伤性脑损伤(traumatic brain injury,TBI)是否有保护作用。方法 TBI通过大鼠可控性皮质打击伤(controlled cortical impact,CCI)产生。门冬氨酸钾组或溶剂对照组在CCI发生后30 min以腹腔注射给予生理盐水或62.5 mg/kg剂量的PA,观察脑血流灌注量,改良神经功能缺损评分(modified Neurological Severity Score,m NSS)和皮质损伤体积,并检测脑水肿以及脑组织三磷腺苷(adenosine triphosphate,ATP)、乳酸含量和钠钾ATP酶活性。结果在CCI引起的大鼠皮质损伤中,与溶剂对照组相比,急性给予62.5 mg/kg剂量的PA治疗可以明显改善神经功能缺损(P<0.05),降低皮质损伤体积(P<0.01),减轻脑水肿(P<0.05)。此外,与溶剂对照组相比,门冬氨酸钾治疗组显著减少ATP缺失(P<0.01),降低乳酸含量(P<0.05),并增加钠钾ATP酶的活性(P<0.05)。结论 PA能通过增加ATP含量和钠钾ATP酶的活性并降低脑水肿,对TBI具有神经保护作用。这为PA在临床脑损伤时的应用提供了实验证据。

一种适用于康复研究的局灶性颅脑外伤大鼠模型

目的:仿制一种适合康复机制研究的局灶性颅脑外伤(TBI)动物模型,为国内广泛开展颅脑损伤康复机制研究提供基础。方法:成年雄性SD大鼠16只,随机分为颅脑外伤组和假手术组各8只。颅脑外伤组制作成控制性皮层损伤(CCI)模型,术后采用神经功能缺失评分、foot-fault test和cylinder test评估动物感觉和运动能力;外伤后第21～25天行Morris水迷宫检查,评估大鼠认知功能的变化;在外伤后28d通过焦油紫(CV)染色检测脑组织病理改变和组织缺失情况。结果:颅脑外伤组大鼠较假手术组神经功能评分有明显降低(P<0.05),运动协调能力和对称使用前肢的能力明显下降(P<0.05),空间学习和记忆能力明显损坏(P<0.05);脑组织明显缺损(P<0.05),缺损组织周边出现神经元变性、坏死,神经元丢失伴胶质细胞增生。结论:控制性皮层损伤的TBI模型大鼠表现明显的感觉、运动、认知功能障碍和相应的病理改变,可以作为一项良好的TBI模型用于康复训练研究。

双侧前额叶中度损伤大鼠执行控制和空间学习与记忆功能的研究

目的:通过控制性皮质撞击法,制作双侧前额叶中度损伤模型并观察其对大鼠的执行控制功能和空间学习与记忆功能的影响。方法:40只雄性SD大鼠随机分成3组:正常对照组(n=10)、假手术组(n=10)、控制性皮质撞击(CCI)组(n=20)。CCI组大鼠应用控制性皮质撞击法制作双侧额叶打击颅脑创伤模型,其中打击速度:3.5m/s,打击深度:1.5mm,停留时间:400ms。于CCI后第4周末及第8周末分别进行GO/NO GO任务测试及水迷宫测试。结果:造模前各组各测试均无显著差异。造模后第4周CCI组GO/NO GO任务测试可见正确率显著下降(P<0.01),造模后第8周,各组的正确率下降和造模前比均有显著性差异(P<0.05)。造模后定位航行实验可见各组潜伏期均有下降,对照组和假手术组下降有显著性差异(P<0.05),但CCI组无显著性差异;第4、8周,与对照组相比,CCI组则均有显著性差异(P<0.01)。造模后第4周空间探索实验可见,对照组和假手术组与造模前相比无显著性差异(P>0.05),CCI组则有显著下降(P<0.01);造模后第8周,假手术组和CCI组与造模前相比差异有显著性意义(P>0.05),CCI组则与第4周相比也有显著差异(P<0.01)。结论:应用CCI方法进行双侧前额叶撞击制备大鼠中度颅脑创伤模型,可以造成大鼠执行控制能力的显著下降,并对大鼠的空间学习和记忆能力均有严重影响。在伤后一定时间内,执行控制能力可能会有部分的自然恢复,但空间学习和记忆能力损害则可能进行性加重。