移植人羊膜细胞对大鼠创伤性脑损伤的实验研究

目的 探究大鼠TBI后脑内移植人羊膜细胞（HACs）对大鼠运动功能的影响。方法 HACs经分离、Hoechst33342标记后重悬调整细胞浓度为10^5/μl；采用改进的Feeney自由落体法打击大鼠脑皮层后肢运动区域，损伤后24h经微量注射器和立体定向仪将Hoechst33342标记的HACs 10μl分别移植于挫伤灶中心和挫伤灶边缘；在TBI后的28d内采用钉板平衡木行走测试大鼠运动功能变化，运动功能检测结束后取出脑组织行组织学检测。结果 治疗组滑落脚步数明显少于对照组（P〈0．05）；移植的HACs呈蓝色荧光；部分移植HACs可见MAP-2阳性表达。结论 移植HACs使大鼠TBI后运动功能明显改善。     

胶质细胞源性神经营养因子基因修饰CD34+细胞静脉移植治疗高血压大鼠脑梗死

背景：近年来,已有实验证实经颅直接给予胶质细胞源性神经营养因子(glial cell-derived neurotrophic factor,GDNF)或携带GDNF基因病毒载体有显著减少脑梗死体积、促进神经功能恢复的疗效,但其治疗方法有创,临床应用有限。 目的：观察GDNF基因转染的人脐血CD34+细胞经静脉移植对自发性高血压大鼠脑梗死的疗效,并探讨其机制。 方法：分离人脐血CD34+细胞,脂质体方法转染pEGFP-GDNF质粒和pEGFP空载体至CD34+细胞制备pEGFP-GDNF-CD34+和pEGFP-CD34+细胞;制备60只雄性自发性高血压大鼠大脑中动脉栓死模型并随机分为3组：pEGFP-GDNF-CD34+细胞移植组(基因细胞组)、pEGFP-CD34+细胞移植组(单纯细胞组)、生理盐水组。改良神经功能损害评分评价神经功能恢复状况;图像分析法观察TTC染色脑梗死体积;酶联免疫法检测细胞培养液与脑组织匀浆GDNF水平,荧光显微镜及免疫组织化学检测绿色荧光蛋白标记CD34+细胞及其人神经胶质纤维酸性蛋白和人神经元核抗原表达。 结果与结论：经静脉移植pEGFP-GDNF-CD34+细胞向自发性高血压大鼠脑缺血区域迁移、存活、并向神经细胞定向分化,促进神经功能恢复。GDNF基因转染CD34+细胞在脑组织存活、向神经细胞分化及对大脑神经功能保护作用优于CD34+细胞。脑组织GDNF水平可能是GDNF基因转染CD34+细胞和单纯CD34+细胞移植治疗自发性高血压大鼠局灶性脑缺血疗效差异机制之一。     

慢病毒转染胶质细胞源性神经营养因子脂肪干细胞脑移植的研究

目的 探讨慢病毒转染胶质细胞源性神经营养因子(GDNF)的脂肪干细胞(ADSCs)脑移植的应用价值.方法 分离、培养SD大鼠ADSCs,用高滴度慢病毒将GDNF转染入细胞,观察细胞形态及用免疫荧光法观察神经标志物的表达.用立体定向仪将转染ADSCs植入大鼠的纹状体,移植1个月和2个月后,用荧光显微镜观察ADSCs脑内存活和分布状况,用Western blot检测GDNF蛋白的表达,并与正常对照组比较.结果 慢病毒转染ADSCs形态类似神经元,胞浆神经元特异性烯醇化酶(NSE)表达阳性.ADSCs移植到大鼠纹状体1个月后,移植部位有大量存活的ADSCs,2个月后,仍有部分存活细胞,并向远处移行,GDNF蛋白水平显著高于正常对照组(均P<0.01).结论 慢病毒转染GDNF的ADSCs可为干细胞移植治疗中枢神经系统疾病提供新的供体.     

TH和GDNF双转基因工程细胞对多巴胺能神经元的保护作用

目的将人的外源基因TH和GDNF共同转染SH-SY5Y细胞,建立一种可同时高效稳定表达TH和GDNF的工程细胞,探讨其在帕金森病(PD)基因治疗中的作用。方法将人GDNF和TH的cDNA构建于表达载体PcDNA3.0和PcDNA3.1,形成重组真核表达载体PcDNA3.1/hGDNF、和PcDNA3.0/hTH,同时转染至SH-SY5Y细胞系,利用RT-PCR鉴定筛选出高效稳定表达阳性克隆,将此工程细胞与大鼠原代多巴胺(DA)能神经元共培养,免疫细胞化学检测观察DA能神经元的数目和生长状态。结果成功建立了可同时高效稳定表达人TH和GDNF双基因的工程细胞,并且该细胞可防止DA能神经元退变死亡,有助于DA能神经元抵抗MPP+的毒性损伤。结论人TH和GDNF双转基因工程细胞对DA能神经原有防治兼顾的保护作用。、     

重组大鼠质粒pEGFP-GDNF的构建和在脊髓内表达的实验研究

采用RT PCR方法从大鼠胎脑组织总RNA中扩增出该基因的全序列cDNA ,并以融合蛋白方式克隆到增强型绿色荧光蛋白 (EGFP)报告基因的真核表达载体中 ,成功构建了重组质粒 pEGFP GDNF在体表达载体。采用基因注射法将阳离子脂质体DC Chol和pEGFP GDNF基因混合后转染至大鼠胸段脊髓组织中 ,观察GDNF在大鼠脊髓中的表达。RT PCR结果表明注射局部GDNFmRNA表达增加。荧光显微镜下观察发现 ,注射局部灰质和白质神经细胞内均有较多绿色荧光蛋白表达。本研究结果提示 ,阳离子脂质体介导GDNF体内转基因的方法是可行的 ,EGFP可作为报告基因观察GDNF在体内的表达。     

高胆固醇对AD大鼠海马神经元缺失和Tau蛋白异常磷酸化的影响

目的 研究高胆固醇饮食对阿尔茨海默病(AD)大鼠海马神经元缺失和Tau(ser202)异常磷酸化的影响.方法 海马齿状同注射B淀粉样蛋白(A13)建立AD大鼠模型,根据不同饮食,将动物分为高胆同醇AD组、高胆同醇磷酸盐缓冲液(PBS)组、标准饮食AD组和标准饮食PBS组;采用尼氏染色方法检测海马神经元缺失率,应用免疫组织化学方法检测海马及皮层Tau(ser202)磷酸化水平.结果 高胆固醇饮食增加海马神经元缺失,高胆固醇饮食AD组海马神经元缺失率(30.9%±4.6%)明显大于标准饮食AD组(22.7%±1.9%)、高胆同醇饮食PBS组(7.O%±1.5%)和标准饮食PBS组(5.4%±1.1%),差异均有统计学意义(P＜0.05);高胆固醇AD组、标准饮食AD组、高胆固醇PBS组、标准饮食PBS组海马齿状回(Pser202)Tau阳性细胞数分别为65.5±6.2、48.8±4.8、22.5±3.1和12.7±1.7,比较差异均有统计学意义(P＜0,05).结论 高胆固醇饮食促进Aβ诱导神经元缺失和Tau蛋白异常磷酸化.     

补肾壮阳胶囊对精神分裂症模型大鼠海马胶质细胞源性神经营养因子表达的影响

目的 探讨补肾壮阳胶囊(WSKY)对地卓西平马来酸盐(MK801)建立的精神分裂症模型大鼠海马胶质细胞源性神经营养因子(GDNF)表达的影响.方法 将40只6周龄SD雄性大鼠随机分为3组:对照组(生理盐水腹腔注射+生理盐水灌胃)、模型组(M K801腹腔注射+生理盐水灌胃)及WSKY+MK801组(MK801腹腔注射+WSKY灌胃,而根据WSKY剂量的不同又分为3个亚组);各组相应处理两周后运用Western Blot和RT-PCR技术分别检测各组大鼠海马区GDNF蛋白及mRNA的表达.结果 与对照组相比较,模型组的GDNF蛋白及mRNA的表达下降,差异有统计学意义(P<0.05);而与模型组相比,WSKY+MK801组中较高剂量WSKY可致GDNF蛋白及其mRNA的表达增加,差异有统计学意义(P<0.05).结论 MK801可致大鼠海马GDNF表达减少,而补肾壮阳胶囊可上调大鼠海马GDNF的表达.     

GDNF基因转染的细胞侧脑室内移植对缺血性脑损伤大鼠的神经保护作用

目的 研究胶质源性神经营养因子GDNF基因转导的细胞侧脑室内移植治疗局灶性缺血性脑损伤大鼠的可行性,并探讨GDNF的神经保护作用机制.方法 体外培养SH-SY5Y细胞株,并用分子克隆技术转导入GFP-GDNF基因,使其可持续分泌绿色荧光蛋白GFP和GDNF.取75只体重150～180 g的健康雄性大鼠,分为移植缺血组、注射缺血组、缺血对照组和正常组等.在立体定向仪介导下向移植缺血组大鼠侧脑室注入转导GDNF基因的SY5Y细胞,向注射缺血组大鼠侧脑室内注射入5U/10μL的GDNF,24 h后采用线栓法对移植缺血组、注射缺血组和缺血对照组动物进行手术,建立局灶性脑缺血损伤模型（即大脑中动脉阻断,MCAO）,在缺血后2 d时用Longa五分法评测行为学改变,TTC染色判断梗塞体积大小,用Western-blot法检测凋亡相关蛋白Bcl-2/Bax的表达水平.结果 在缺血损伤两天后,移植缺血组动物的肢体功能恢复效果优于缺血对照组,TTC染色亦提示移植缺血组脑梗死体积小于缺血对照组和注射缺血组（P＜0.01）.缺血灶周围脑组织凋亡相关蛋白Bcl-2和Bax含量均明显增高,移植缺血组Bcl-2/Bax的比值高于缺血对照组和注射缺血组.结论 GD-NF对缺血性脑损伤大鼠有神经保护作用,用GDNF基因转导的细胞移植治疗是一种可行的途径,效果优于经侧脑室直接给药.GDNF可调节凋亡相关蛋白Bcl-2/Bax的表达,这可能为其神经保护作用的机制之一.     

大鼠轻型颅脑损伤后星形胶质细胞与神经元的病理改变

目的 探讨轻型颅脑损伤（TBI）后神经元及星形胶质细胞改变的病理生理过程。方法 将24只成年SD大鼠随机分为轻型TBI组（n=18）和假手术组（n=6）,轻型TBI组又分为伤后3 h（n=6）、伤后24 h（n=6）、伤后72 h（n=6）三亚组。采用液压冲击法制作轻型TBI模型。采用胶质纤维酸性蛋白（GFAP）染色检测星形胶质细胞,采用Fluoro-Jade B（FJ-B）荧光染色检测变性神经元。结果 与假手术组相比,轻型TBI后3 h、24 h、72 h邻近顶叶皮质、海马CA2/3区GFAP阳性细胞数量均明显减少（P<0.05）;缺失区周围星形胶质细胞肿胀增生明显。FJ-B阳性神经元在损伤后3 h无明显增加（P>0.05）,伤后24 h皮层区FJ-B阳性神经元显著增加（P<0.05）,伤后72 h海马区FJ-B阳性神经元显著增加（P<0.05）。伤后72 h伤侧皮层区与海马区GFAP阳性细胞数和FJ-B阳性细胞数呈显著负相关（r=-0.8285,P<0.05）。结论 轻型TBI后星形胶质细胞超急性期（3 h）即出现损害和胶质反应,神经元则在急性期（24 h）至亚急性期（72 h）出现明显损害,星形胶质细胞缺失程度可以反应神经元损伤程度。     

脑源性神经营养因子基因重组慢病毒转染骨髓间质干细胞移植治疗大鼠脑出血的实验研究

目的 观察脑源性神经营养因子(BDNF)基因重组慢病毒转染骨髓间质干细胞(MSCs)移植治疗大鼠脑出血的疗效.方法 分离培养大鼠MSCs;将带有BDNF的慢病毒载体转染MSCs;RT-PCR、蛋白质印迹检测转基因MSCs BDNF基因及蛋白水平表达.制备大鼠脑出血模型,采用抽签法随机分为磷酸盐缓冲液(PBS)组、MSCs组、空病毒转染骨髓问质干细胞(MSCs-EGFP)组、脑源性神经营养因子基因重组慢病毒转染骨髓间质干细胞(MSCs-EGFP-BDNF)组,每组15只.72 h后细胞移植,记录各组细胞移植后7、14、21 d神经功能缺损改善程度;免疫荧光双标检测MSCs脑内迁移和分化情况.结果 MSCs-EGFP-BDNF组BDNF基因及蛋白水平表达明显高于MSCs组及MSCs-EGFP组;与PBS组(7 d:2.0±0.4,14 d:1.7 ±0.2,21 d:1.3±0.2)相比,MSCs组(7 d:1.6±0.2,14 d:1.2 ±0.3,21 d:0.8±0.2)、MSCs-EGFP组(7 d:1.6±0.3,14 d:1.1 ±0.2,21 d:0.8 ±0.3)及MSCs-EGFP-BDNF组(7 d:1.2±0.3,14 d:0.6±0.1,21 d:0.2 ±0.2)大鼠神经功能评分均有不同程度改善(F=6.667、18.417、20.882,均P＜0.05),其中MSCs-EGFP-BDNF组改善最为显著;免疫荧光双标显示MSCs-EGFP-BDNF组胶原纤维酸性蛋白、神经元特异性核蛋白、环核苷酸磷酸二酯酶阳性率明显高于MSCs组及MSCs-EGFP组,而MSCs组与MSCs-EGFP组比较差异无统计学意义.结论 BDNF基因重组慢病毒修饰的MSCs基因及蛋白水平表达均增高;修饰的MSCs移植后可迁移至脑出血灶周围存活并分化表达神经细胞标志物,促进脑出血后神经功能修复.     

The tumor-suppressor gene, p53, is induced in injured brain regions following experimental traumatic brain injury.

A growing body of evidence suggests that neurons undergo apoptotic cell death following traumatic brain injury (TBI). Since the expression of several tumor suppressor and cell cycle genes have been implicated in neuronal apoptosis, the present study used in situ hybridization (ISH) histochemistry to evaluate the regional and temporal patterns of expression of the mRNAs for the tumor suppressor gene, p53, and the cell cycle gene, cyclin D1, following lateral fluid-percussion (FP) brain injury in the rat. Anesthetized adult male Sprague-Dawley rats (n=16) were subjected to lateral FP brain injury of moderate severity (2.4-2.7 atm), while sham controls (n=6) were surgically prepared but did not receive brain injury. Animals were killed by decapitation at 6 h (n=6 injured and 2 sham), 24 h (n=6 injured and 2 sham), or 3 days (n=4 injured and 2 sham), and their brains processed for ISH. Little to no expression of p53 mRNA was observed in sham brains. At 6 h post-injury, p53 mRNA was induced predominantly in cells that are vulnerable to TBI, such as those in the contused cortex, lateral and medial geniculate nuclei of the thalamus, and the CA(3) and hilar neurons of the hippocampus. Increased p53 mRNA was also detected in hippocampal CA(1) neurons, cells that are relatively resistant to FP brain injury. Levels of p53 mRNA returned to sham levels in all regions of the injured brain by 24 h. In contrast to p53, cyclin D1 mRNA was detectable in the brains of uninjured animals and was not altered by brain injury. These results suggest that the tumor suppressor gene p53, but not cyclin D1, is upregulated and may participate in molecular response to TBI.     

大鼠脑缺血再灌注后星形胶质细胞反应性变化差异与海马CA1区的迟发性神经元死亡

BACKGROUND： Blood supply to the hippocampus is not provided by the middle cerebral artery. However, previous studies have shown that delayed neuronal death in the hippocampus may occur following focal cerebral ischemia induced by middle cerebral artery occlusion.
OBJECTIVE： To observe the relationship between reactive changes in hippocampal astrocytes and delayed neuronal death in the hippocampal CA1 region following middle cerebral artery occlusion.
DESIGN, TIME AND SETTING： The immunohistochemical, randomized, controlled animal study was performed at the Laboratory of Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, from July to November 2007.
MATERIALS： Rabbit anti-glial fibrillary acidic protein （GFAP） （Neomarkers, USA）, goat anti-rabbit IgG （Sigma, USA） and ApoAlert apoptosis detection kit （Biosciences Clontech, USA） were used in this study. METHODS： A total of 42 healthy adult male Wistar rats, aged 3–5 months, were randomly divided into a sham operation group （n = 6） and a cerebral ischemia/reperfusion group （n = 36）. In the cerebral ischemia/reperfusion group, cerebral ischemia/reperfusion models were created by middle cerebral artery occlusion. In the sham operation group, the thread was only inserted into the initial region of the internal carotid artery, and middle cerebral artery occlusion was not induced. Rats in the cerebral ischemia/reperfusion group were assigned to a delayed neuronal death （＋） subgroup and a delayed neuronal death （–） subgroup, according to the occurrence of delayed neuronal death in the ischemic side of the hippocampal CA1 region following cerebral ischemia.
MAIN OUTCOME MEASURES： Delayed neuronal death in the hippocampal CA1 region was measured by Nissl staining. GFAP expression and delayed neuronal death changes were measured in the rat hippocampal CA1 region at the ischemic hemisphere by double staining for GFAP and TUNEL.
RESULTS： After 3 days of ischemia/reperfusion, astrocytes with abnormal morphology were detected in the rat hippocampal CA1 region in the delayed neuronal death （＋） subgroup. No significant difference in GFAP expression was found in the rat hippocampal CA1 region at the ischemic hemisphere in the sham operation group, delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup （P 〉 0.05）. After 7 days of ischemia/reperfusion, many GFAP-positive cells, which possessed a large cell body and an increased number of processes, were activated in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression in the hippocampal CA1 region was greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.01）. Moreover, GFAP expression was significantly greater in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.01）. After 30 days of ischemia/reperfusion, GFAP-positive cells were present in scar-like structures in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression was significantly greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.05）. GFAP expression was significantly lower in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.05）. The delayed neuronal death rates were 42% （5/12）, 33% （4/12） and 33% （4/12） at 3, 7 and 30 days, respectively, followingischemia/reperfusion. No significant differences were detected at various time points （χ2 = 0.341, P 〉 0.05）.
CONCLUSION： The activation of astrocytes was poor in the hippocampal CA1 region during the early stages of ischemia, which is an important reason for delayed neuronal death. Glial scar formation aggravated delayed neuronal death during the advanced ischemic stage.     

Dose-dependent neuronal injury after traumatic brain injury

The Fluoro-Jade (FJ) stain reliably identifies degenerating neurons after multiple mechanisms of brain injury. We modified the FJ staining protocol to quickly stain frozen hippocampal rat brain sections and to permit systematic counts of stained, injured neurons at 4 and 24 h after mild, moderate or severe fluid percussion traumatic brain injury (TBI). In adjacent sections, laser capture microdissection was used to collect uninjured (FJ negative) CA3 hippocampal neurons to assess the effect of injury severity on mRNA levels of selected genes. Rats were anesthetized, intubated, mechanically ventilated and randomized to sham, mild (1.2 atm), moderate (2.0 atm) or severe (2.3 atm) TBI. Four or 24 h post-TBI, ten frozen sections (10 microm thick, every 15th section) were collected from the hippocampus of each rat, stained with FJ and counterstained with cresyl violet. Fluoro-Jade-positive neurons were counted in hippocampal subfields CA1, CA3 and the dentate gyrus/dentate hilus. At both 4 and 24 h post-TBI, numbers of FJ-positive neurons in all hippocampal regions increased dose-dependently in mildly and moderately injured rats but were not significantly more numerous after severe injury. Although analysis of variance demonstrated no overall difference in expression of mRNA levels for heat shock protein 70, bcl-2, caspase 3, caspase 9 and interleukin-1beta in uninjured CA3 neurons at all injury levels, post hoc analysis suggested that TBI induces increases in neuroprotective gene expression that offset concomitant increases in deleterious gene expression.     

酸敏感离子通道2a对缺血预处理诱导大鼠海马缺血耐受的作用

目的探讨脑缺血时的组织病理学变化及酸敏感离子通道2a（ASIC2a）在缺血预处理诱导的脑缺血模型耐受中的作用。方法取成年雄性SD大鼠160只,随机分为假手术组、预缺血组、缺血组、缺血预处理组共4组。行焦油紫染色观察各组大鼠海马CAI区存活神经元密度,TUNEL染色观察大鼠海马CA1区神经元凋亡情况,RT—PCR和Western blotting检测ASIC2a在大鼠海马CAl区mRNA和蛋白表达情况。结果缺血预处理能够显著减少大鼠海马CA1区锥体神经元的死亡和凋亡,PC＋Isch组和Isch组相比具有显著性差异（P〈0．01）。全脑缺血能够上调ASIC2a在大鼠海马CA1区mRNA和蛋白表达,在24h达到高峰,而缺血预处理进一步上调ASIC2a表达,呈进行性上升,在24h和72h时相点,PC＋Isch组和Isch组相比具有显著性差异（P〈0．01）。结论在脑缺血耐受中,缺血预处理对第二次致死性缺血表现出保护作用。在这个过程中,大鼠海马CA1区ASIC2a基因和蛋白表达上调发挥了重要的保护作用。     

Expression of glial cell line-derived neurotrophic factor induced by transient forebrain ischemia in rats.

This study examined the expression of glial cell line-derived neurotrophic factor (GDNF) mRNA and the cellular localization of GDNF production in rats subjected to transient forebrain ischemia induced by four-vessel occlusion. Transient forebrain ischemia induced GDNF mRNA expression in the hippocampus from 3 h to 3 days after the ischemic episode, with peak expression at 6 h. The GDNF mRNA increase in the cerebral cortex was similar to that in the hippocampus, whereas no increase in GDNF mRNA was observed in the striatum and brainstem. Western blot analysis showed that GDNF in the hippocampal CA1 region was increased slightly from 3 to 24 h after the ischemia, and then subsequently declined to below the baseline level. In the hippocampus, GDNF was evenly produced in pyramidal neurons of both sham-operated rats and normal rats, as determined by immunohistochemistry. Interestingly, we found that ischemia-induced reactive astrocytes, as well as surviving neurons, produced GDNF in 3-7 days after the ischemia. On the other hand, in other regions, such as the cerebral cortex, striatum, and brainstem, there was no change in GDNF-positive cells secondary to ischemia. These findings suggest that expression of GDNF mRNA is regulated in part via ischemia-induced neuronal degeneration. They also suggest that ischemia-induced reactive astrocytes may produce GDNF to protect against neuronal death. Therefore, GDNF may play an important role in ischemia-induced neuronal death in the brain.     

雷公藤内酯对海人酸致痫大鼠海马神经元的保护作用及相关PUMA蛋白表达的影响

目的探讨雷公藤内酯对海人酸致痫大鼠海马神经元的保护作用及对海马神经元PUMA(P53上调的细胞凋亡调控因子)蛋白表达的影响。方法 30只SD大鼠随机分成3组,其中对照组10只,海人酸组10只,雷公藤内酯干预组10只。结晶紫染色观察海马神经元的形态变化,免疫组化染色法检测海马神经元PUMA蛋白的表达。结果结晶紫染色结果显示,海人酸组中,海马神经元变性或丢失,胞体皱缩,形态不规则。而雷公藤内酯干预组中海马神经元的数量和形态与对照组相似,胞浆清晰淡染,核仁清楚。免疫组化染色结果显示,海人酸组中海马神经元PUMA蛋白表达水平与对照组比较显著增多(P<0.05);雷公藤内酯干预组中海马神经元PUMA蛋白表达水平与海人酸组比较显著减少(P<0.05)。结论雷公藤内酯对海人酸致痫大鼠海马神经元具有保护作用;其可下调海马神经元PUMA蛋白的表达,抑制海人酸致痫大鼠海马神经元凋亡。     

Traumatic brain injury causes a long-lasting calcium (Ca2+)-plateau of elevated intracellular Ca levels and altered Ca2+ homeostatic mechanisms in hippocampal neurons surviving brain injury

Traumatic brain injury (TBI) survivors often suffer chronically from significant morbidity associated with cognitive deficits, behavioral difficulties and a post-traumatic syndrome and thus it is important to understand the pathophysiology of these long-term plasticity changes after TBI. Calcium (Ca2+) has been implicated in the pathophysiology of TBI-induced neuronal death and other forms of brain injury including stroke and status epilepticus. However, the potential role of long-term changes in neuronal Ca2+ dynamics after TBI has not been evaluated. In the present study, we measured basal free intracellular Ca2+ concentration ([Ca2+](i)) in acutely isolated CA3 hippocampal neurons from Sprague-Dawley rats at 1, 7 and 30 days after moderate central fluid percussion injury. Basal [Ca2+](i) was significantly elevated when measured 1 and 7 days post-TBI without evidence of neuronal death. Basal [Ca2+](i) returned to normal when measured 30 days post-TBI. In contrast, abnormalities in Ca2+ homeostasis were found for as long as 30 days after TBI. Studies evaluating the mechanisms underlying the altered Ca2+ homeostasis in TBI neurons indicated that necrotic or apoptotic cell death and abnormalities in Ca2+ influx and efflux mechanisms could not account for these changes and suggested that long-term changes in Ca2+ buffering or Ca2+ sequestration/release mechanisms underlie these changes in Ca2+ homeostasis after TBI. Further elucidation of the mechanisms of altered Ca2+ homeostasis in traumatized, surviving neurons in TBI may offer novel therapeutic interventions that may contribute to the treatment and relief of some of the morbidity associated with TBI.     

Delayed neuronal death and damage of GDNF family receptors in CA1 following focal cerebral ischemia

Delayed neuronal death (DND) of pyramidal neurons in the CA1 and CA3 regions of the hippocampus has been extensively studied following global brain ischemia, whereas only little is known about DND in this highly vulnerable brain region after focal brain ischemia. In the present study, the distribution and time course of hippocampal neuronal apoptosis were studied following transient middle cerebral artery occlusion (MCAO) in rats 1, 3, 7, 14, and 30 days after the insult. In 60% of the animals, more than 90% of CA1 pyramidal neurons showed strong nick-end labeling (TUNEL) staining at day 3 with fragmentation and marginalization of the nuclei in approximately 40% of these cells. The number of TUNEL-positive cells decreased within the next days, but 30 days after MCAO, some apoptotic neurons were still present. Analysis of the expression of the glial cell line-derived neurotrophic factor (GDNF) and its receptors GFRalpha1, GFRalpha2, and GFRalpha3 using triple immunofluorescence and confocal laser scanning microscopy revealed that in all animals showing marked hippocampal DND, the neuronal staining for GFRalpha1, GFRalpha3, and GDNF decreased prior to the onset of TUNEL staining in CA1. After 7 days, some apoptotic neurons still expressed GFRalpha3, whereas only few showed GFRalpha1 immunoreactivity, indicating that GFRalpha1 may be beneficial for the survival of hippocampal neurons. The data suggest that reduced expression of GDNF and impairment of GFRalpha1/3 may contribute to hippocampal DND after focal brain ischemia.