FTY720对大鼠急性脊髓损伤后caspase-3表达及细胞凋亡的影响

目的 探讨一种新型免疫抑制剂FTY720对大鼠急性脊髓损伤后caspase-3表达及细胞凋亡的影响。材料及方法 采用SD大鼠120只,随机分成A、B、C3组,每组40只,制作Allen’s胸9、10脊髓损伤模型。C组（FTY720治疗组）：以FTY720按3mg/kg生理盐水稀释至0.3ml灌胃。B组（对照组）：以等量生理盐水灌胃。A组（假手术组）：大鼠麻醉后仅切除胸9、10椎板,不打击脊髓,缝合后立即以等量生理盐水灌胃。分别于术后6小时、12小时、24小时、48小时、72小时处死大鼠,每次各组各8只,取损伤段脊髓超薄切片,行S-P免疫组化染色及Tunel染色,观察各组caspase-3表达及细胞凋亡情况,并计算各组免疫组化染色阳性细胞比值,进行统计学分析。结果A组各时间点几乎见不到Caspase-3和细胞凋亡表达阳性细胞。B组大鼠急性脊髓损伤后6小时出现caspase-3及细胞凋亡表达,伤后伤后12小时持续升高,到伤后24小时达高峰,伤后48小时开始减弱,伤后72小时进一步减弱,但仍维持较高水平; caspase-3表达及细胞凋亡同步,二者之间存在正相关（г=0.864,Ｐ＜０.０５）。而FTY720治疗组（C组）,虽然在caspase-3和细胞凋亡表达的周期上与损伤组相同,但caspase-3和细胞凋亡表达阳性的细胞数却显著低于对照组（B组）（Ｐ＜０.０５）。结论FTY720可以显著减少大鼠急性脊髓损伤后Caspase-3的表达及神经细胞凋亡,其具体机制还有待于进一步研究。     

一氧化氮合酶对脑损伤后神经细胞凋亡的影响

目的探讨脑损伤后神经型一氧化氮合酶（nNOS）和诱生型一氧化氮合酶（iNOS）对神经细胞凋亡的影响及其相关机制。方法320只SD大鼠随机分成以下4组：假手术组、脑创伤组、7-硝基吲唑组（nNOS抑制剂）和氨基胍组（iNOS抑制剂），此4组分别划分为伤后3h、6h、12h、24h、2d、3d、7d、14d8个时相组，每个时相组均为10只大鼠，采用Marmarou法制造大鼠重型弥漫性颅脑创伤模型，运用末端脱氧核苷酸转移酶介导的生物素脱氧尿嘧啶核苷酸缺口标记法（TUNEL）和免疫组化法，观察4组不同时相点海马CA1区的神经细胞凋亡情况和Bcl-2、Fas的表达情况。结果①假手术组偶见TUNEL阳性凋亡细胞及Bcl-2、Fas阳性细胞；②脑创伤组，伤后各时相点均出现TUNEL阳性凋亡细胞及Bcl-2阳性细胞，先上升后下降；③7-硝基吲唑（7-NI）组，伤后6h、12h、24h凋亡细胞明显下降而Bcl-2阳性细胞却明显上升（同脑创伤组比较P〈0．05）；④氨基胍（AG）组，伤后2～7d，凋亡细胞及Fas阳性细胞明显下降（同脑创伤组比较P〈0．01）。结论在脑损伤的早期，nNOS能够通过抑制Bcl-2的表达来促进神经细胞的凋亡；在脑损伤的晚期，iNOS能够通过诱导Fas的表达来促进神经细胞的凋亡。     

银杏叶提取物EGb761抑制脊髓损伤后的细胞凋亡

目的： 探讨银杏叶提取物EGb761对实验性大鼠脊髓损伤后神经保护的作用及其机制。方法： 成年雄性SD大鼠132 只,体重200~250g,随机分为正常对照组（N组）、损伤组（T组）、甲基强的松龙治疗组（MP组）和 EGb761 治疗组（EGb761组）,每组 33 只。T组、MP组、EGb761组用改良 Allen法以25GCF损伤力度致伤大鼠,建立 T9 脊髓中度损伤模型。术后4h、8h、24h每组随机取3只动物切取损伤区1cm脊髓节段,分别用黄嘌呤氧化酶法和硫代巴比妥酸（TBA）法测定脊髓组织中超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量。分别于术后24h、 3d、 5d、 7d、 14d 处死动物(n=6),快速取T9 节段脊髓,TUNEL法标记细胞凋亡,免疫组化方法检测诱生型一氧化氮合酶（iNOS）的表达。结果：术后4h、8h、24h EGb761治疗组SOD活性及MDA含量与损伤对照组比较均有显著差异（P<0.01）。术后各时相点EGb761治疗组神经细胞凋亡指数和iNOS表达阳性细胞率均低于损伤对照组（P<0.01或P<0.05）。结论：EGb761能抑制脊髓损伤后的脂质过氧化反应,减轻神经细胞的凋亡,其机制可能与抑制iNOS表达有关。     

高压氧预处理对大鼠急性脊髓损伤后神经细胞凋亡的影响

目的探讨高压氧预处理对急性脊髓损伤后不同时期神经细胞凋亡的影响及神经保护机制。方法将55只SD大鼠随机分为高压氧预处理组（25只）、正常损伤组（25只）及对照组（5只）。大鼠急性脊髓损伤模型制作采用改良Allen＇s法，分别于伤后1d、5d、7d、10d和14d在脊髓损伤部位取材，应用苏木精-伊红染色、原位缺口末端标记（TUNEL）方法检测大鼠脊髓损伤后的神经细胞凋亡情况。结果预处理组和单纯损伤组均见TUNEL阳性凋亡细胞，而预处理组凋亡细胞数减少；在各时间点预处理组与单纯损伤组差异均有统计学意义（P〈0．05）。结论高压氧预处理可减少继发性脊髓损伤细胞凋亡，因而可促进脊髓损伤后修复，对中枢神经系统损伤具有保护作用。     

许旺细胞-海藻酸钠凝胶移植修复大鼠脊髓损伤*

目的：观察许旺细胞-海藻酸钠凝胶移植对大鼠脊髓损伤后细胞凋亡、Bcl-2表达及下肢运动功能恢复的影响。 方法：清洁级SD大鼠随机分为4组：正常对照组、单纯损伤组、许旺细胞组、许旺细胞-海藻酸钠凝胶组。后3组制作脊髓全横断损伤模型。正常对照组、单纯损伤组不进行移植处理,许旺细胞组植入吸附许旺细胞悬液的明胶海绵块、许旺细胞-海藻酸钠凝胶组植入许旺细胞-海藻酸钠凝胶。分别于 12 h,1,3,7,21 d对动物进行BBB评分后处死,取损伤区脊髓节段制成石蜡切片进行TUNEL、Bcl-2染色,观察脊髓内凋亡细胞、Bcl-2细胞的数量及分布变化。 结果：正常对照组仅有少量淡染Bcl-2阳性细胞;单纯损伤组神经元Bcl-2免疫反应阳性细胞表达的高峰在第3天,14 d时Bcl-2免疫反应阳性细胞表达接近正常水平。许旺细胞-海藻酸钠凝胶移植后损伤脊髓细胞Bcl-2免疫反应阳性细胞表达具有显著增高(P < 0.05),7 d高度表达并持续2周以上。单纯损伤组脊髓内细胞凋亡最多,并于损伤后1,7 d形成两个高峰,多分布于白质中。许旺细胞-海藻酸钠凝胶组BBB评分较单纯损伤组及许旺细胞组明显提高(P < 0.05)。 结论：许旺细胞-海藻酸钠凝胶移植能抑制大鼠脊髓损伤后脊髓细胞凋亡、促进Bcl-2的表达,提高了脊髓运动功能的恢复,但未达到正常水平。 关键词：脊髓损伤;细胞凋亡;许旺细胞;Bcl-2     

NG2细胞的增殖活化对大鼠脊髓损伤后神经病理性疼痛产生和维持的影响

目的探讨NG2细胞在脊髓损伤(SCI)后神经病理性疼痛的产生和维持中的作用。方法将100只健康成年雄性SD大鼠按随机数字表法分为对照组(n=20, 不做任何干预措施)、假手术组(n=40, 暴露T10节段但不实施脊髓撞击)及SCI组(n=40, 暴露T10节段并采用改进型Allen’’s法构建SCI模型)。分别于术前1 d及术后14 d、21 d、28 d时, 应用Von Frey纤维探针检测大鼠后肢的机械缩足反射阈值(MWT), 采用免疫荧光染色检测大鼠脊髓背角NG2阳性细胞数量占细胞总数比例, 应用Western blotting实验检测大鼠脊髓背角硫酸软骨素蛋白多糖(CSPG)的表达。结果术后14 d、21 d、28 d时, SCI组大鼠后肢MWT均明显低于对照组及假手术组, 脊髓背角NG2阳性细胞数量占细胞总数比例均明显高于对照组及假手术组, 脊髓背角CSPG表达均明显高于对照组及假手术组, 差异均有统计学意义(P<0.05)。SCI组大鼠术前1 d及术后14 d、21 d、28 d时的后肢MWT呈现先下降后回升趋势, 脊髓背角NG2阳性细胞数量占细胞总数比例呈现先上升后...     

脑出血大鼠脑组织IGF-1的表达及其对细胞凋亡的影响

目的研究胰岛素样生长因子-1（IGF-1）在实验性大鼠脑出血（ICH）后脑组织中的表达及其对细胞凋亡的影响。方法应用立体定向技术，将自体未抗凝血注入大鼠基底节区以制备ICH模型；将动物分为正常对照组、ICH组及干预组，分别在不同时间断头取脑以制作标本，连续切片分别作IGF-1免疫组化染色及TUNEL染色。结果ICH后2h血肿周围脑组织表达IGF-1，24h达表达高峰，7d时恢复正常；TUNEL染色阳性细胞于ICH后8h开始出现，3d时达高峰，7d时仍有表达；给予外源性IGF-1后，凋亡细胞显著减少，与同时点ICH组相比差别有显著性。结论ICH后IGF-1可抑制细胞凋亡的发生，从而减轻ICH后继发性脑损伤。     

实验性脑出血大鼠脑内Caspase-3mRNA的表达作用研究

目的动态观察实验性脑出血大鼠脑内血肿周围神经细胞凋亡情况和Caspas-3蛋白及mRNA表达水平的变化,探讨脑H{血后血肿周围神经细胞损伤机制。方法健康雄性Wistar大鼠随机分为生理盐水对照组、假手术组和脑出血模型组,分为术后3h,6h,12h,24h,48h,3d,5d,7d共8个时相点,采用尾状核注射自体非抗凝动脉血复制大鼠脑出血模型,术后制作冰冻切片,对切片进行TUNEL染色,以及Caspase-5免疫组化和原位杂交染色,之后利用图像分析仪,观察阳性细胞数。结果脑出血后3h血肿周围尚无凋亡细胞出现,6h有凋亡发生,以后逐渐增多,3d达高峰后逐渐下降,生理盐水对照组仅有少量TUNEL阳性细胞。假手术组及生理盐水对照组3h无Caspase-3蛋白和mRNA表达,生理盐水对照组6h以后有少量表达,脑出血模型组在6hCaspase-3蛋白和mRNA开始表达,3d时Caspase-3的蛋白达到高峰,5d以后逐渐下降,24hCaspase-3mRNA表达达高峰,5d以后逐渐下降。脑出血后血肿周围脑组织Caspase-3蛋白的表达与TUNEL阳性细胞数呈正相关（r=0．515,P〈0．05）;Caspase-3蛋白表达与mRNA表达呈正相关（r=0．625,P〈0．05）。结论脑出血后血肿周围神经细胞损伤有凋亡机制参与,在出血后6h发生凋亡,第3天达高峰。Caspase-3的表达在Caspase-5蛋白水平变化趋势与脑m血后细胞凋亡的趋势一致,Caspase-3的mRNA水平的表达高峰时间先于Caspase-3蛋白的表达及凋亡的发生,提示Caspase-3的表达决定脑出血后细胞凋亡的发生,在脑出血后细胞凋亡中起促进作用。     

2ME2对脊髓损伤大鼠运动功能及凋亡相关基因caspase-3表达的影响

目的探讨2-甲氧基雌二醇(2ME2)对脊髓损伤(SCI)大鼠运动功能及细胞凋亡相关基因caspase-3表达的影响。方法成年雄性SD大鼠72只按随机数字表法分为假手术组、脊髓损伤组和2ME2治疗组,每组24只,采用改良的Allen’s法制作脊髓损伤模型,2ME2干预组大鼠自脊髓损伤模型建立后第1天开始按24 mg/kg给予2ME2腹腔注射,连续注射7 d,在造模成功后1 d、3 d、7 d、14 d、21 d、28 d采用BBB运动评分系统对各组大鼠运动功能进行评估,造模成功后第7天应用免疫荧光技术检测各组大鼠caspase-3表达,应用TUNEL染色进行凋亡细胞计数。结果造模后14 d、21 d、28 d 2ME2治疗组BBB评分显著高于脊髓损伤组,差异具有统计学意义(P<0.05),与假手术组相比,脊髓损伤组及2ME2治疗组caspase-3表达阳性细胞数及凋亡细胞数显著增加,差异具有统计学意义(P<0.05),2ME2治疗组较脊髓损伤组caspase-3表达阳性细胞数及凋亡细胞数显著减少,差异具有统计学意义(P<0.05)。结论 2ME2治疗能改善脊髓损伤大鼠肢体运动功能,具有一定神经保护作用,其治疗机制可能与通过抑制脊髓损伤后的进一步细胞凋亡相关基因的表达有关。     

胎鼠神经干细胞移植对大鼠脊髓损伤后神经细胞凋亡及凋亡抑制基因Bcl-2表达的影响

目的研究胎鼠神经干细胞(NSCs)移植对大鼠脊髓损伤(SCI)后神经细胞凋亡及凋亡抑制基因Bcl-2表达的影响。方法 40只SD大鼠随机分为正常对照组(Normal组),脊髓损伤组(SCI组),神经干细胞组(NSC组),神经干细胞标记组(BrdU+NSCs组)。采用电控脊髓损伤打击装置制作模型,5-溴脱氧尿嘧啶核苷(Br-dU)法标记处于对数生长期的NSCs,SCI后即刻进行NSCs移植。免疫组化法观察BrdU标记NSCs的存活、迁移及凋亡抑制基因Bcl-2的表达,TUNEL法标记凋亡细胞(免疫组化及免疫荧光显色),改良Rivlin法观察大鼠后肢运动功能的恢复情况。结果 BrdU+NSCs组在损伤脊髓区域可检测到BrdU标记的阳性NSCs。BrdU+NSC组与NSC组各时间点凋亡阳性细胞数均比SCI组减少(P<0.01),Bcl-2免疫阳性细胞光密度值比SCI组明显增加(P<0.01),且Bcl-2表达高峰延长至伤后7d;移植后7d、14d、28d后肢运动功能评分较SCI组明显升高(P<0.01)。Br-dU+NSC组与NSC组之间比较无明显差异(P>0.05)。结论体外培养的胚胎大鼠NSCs可在脊髓损伤区域存活、迁移,并能通过上调Bcl-2的表达来抑制大鼠脊髓损伤后神经细胞的凋亡,从而促进大鼠瘫痪肢体功能的恢复。     

Neuroprotective effects of the immunodepressant FTY720 on caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury

BACKGROUND:Studies on the immunodepressant FTY720 have primarily focused on organ transplantation and autoimmune disease therapy.However,the effects on caspase-3 expression and neural apoptosis following acute spinal cord injury remain uncertain.OBJECTIVE:To elucidate the underlying mechanism of the immunodepressant FTY720 to alleviate spinal cord injury by inhibiting expression of caspase-3 and neural apoptosis.DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment was performed at Central Laboratory of the Second Affiliated Hospital of Dalian Medical University from April to July 2009.MATERIALS:FTY720 was provided by Wuhan Yuancheng Technology Developing,China.METHODS:A total of 120 Sprague Dawley rats were randomly assigned to sham-surgery,model,and FTY720 groups.Spinal cord injury at the T9-10 segment was induced in model groups using the free-fall method.Following establishment of spinal cord injury at the T9-10 segment in the FTY720 group,rats were treated with an intragastric injection of 0.3 mL saline-diluted FTY720 (3 mg/kg).MAIN OUTCOME MEASURES:At 6,12,24,48,and 72 hours following spinal cord injury,caspase-3 expression was detected using streptavidin-peroxidase immunohistochemistry,and neural apoptosis was detected using the TUNEL method.RESULTS:Positive caspase-3 expression and neural apoptosis was not observed in the sham-surgery group at the various time points.The number of apoptotic cells increased with time after acute spinal cord injury,peaked at 24 hours following injury,and then gradually reduced.However,neural apoptosis remained at a high level.Caspase-3 expression positively correlated with neural apoptosis (r= 0.864,P< 0.05).Caspase-3 expression and neural apoptosis significantly decreased following FTY720 therapy (P< 0.05).CONCLUSION:FTY720 significantly reduced caspase-3 expression and neural apoptosis in a rat model of acute spinal cord injury.     

Ependymal cell proliferation and apoptosis following acute spinal cord injury in the adult rat

BACKGROUND: Studies have reported that spinal cord injury can induce the reactive proliferation of ependymal cells and secondarily cause the apoptosis of nerve cells. However, there is no generally accepted theory on the apoptotic characteristics of ependymal cells in the injured spinal cord.OBJECTIVE: To observe the reactive proliferation and apoptosis of ependymal cells in adult rats following acute spinal cord injury.DESIGN, TIME AND SETTING: A randomized control study based on neuropathology was performed in the Third Military Medical University of Chinese PLA between 2005 and 2007.MATERIALS: Forty healthy, adult, Wistar rats were included in the present study.METHODS: Moderate spinal cord injury was established in twenty rats using Feeney's method, while the remaining 20 rats served as controls and were only treated with laminectomy. All rats were injected intraperitoneally with 1.25 mL of BrdU solution (10 mg BrdU/mL saline) 3 times at 4 hours intervals during the 12 hours prior to sacrifice.MAIN OUTCOME MEASURES: Ependymal cell proliferation and apoptosis in the rat spinal cord were determined by BrdU and nestin immunofluorescence double-labeling, as well as the TUNEL method, at 1, 3, 7, and 14 days after operation.RESULTS: In the moderate spinal cord injury rats, nestin expression was observed in the cytoplasm of ependymal cells. One day immediately following surgery, ependymal cells were BrdU-labeled. The number of BrdU-positive cells increased at 3 days, reached a peak at 7 days, and gradually reduced thereafter. The ependyma developed ti'om a constitutive monolayer cells to a multi-layer cell complex. Some BrdU/Nestin double-positive ependymal cells migrated out from the ependyma. TUNEL-positive cells were also detected in the ependyma in the central region, as well as ischemic regions of the injured spinal cord. In addition, TUNEL-positive cells were visible in the ependyma. No TUNEL-positive ependymal cells were observed in the normal spinal cord.CONCLUSION: Proliferating ependymal cells induced apoptosis in the central and surrounding region following spinal cord injury.     

Neuroprotective effect of estrogen after chronic spinal cord injury in ovariectomized rats

BACKGROUND: At present, there is still lack of effective drugs for chronic spinal cord injury, whereas it is found recently that estrogen has a neuroprotective effect on brain and spinal cord injuries. OBJECTIVE: To observe the effect of estrogen on the apoptosis of nerve cells after gradual chronic spinal cord injury in ovariectomized rats. DESIGN: A randomized controlled animal trial. SETTING: Institute of Orthopaedics, the Second Hospital of Lanzhou University. MATERIALS: Sixty-five female Wistar rats of common degree, weighing 220–250 g, were provided by the experimental animal center of Lanzhou University. The rats were randomly divided into sham-operated group (n =5), estrogen-treated group (n =30) and saline control group (n =30), and the latter two groups were observed at 1, 3, 7, 14, 28 and 60 days respectively, and 5 rats for each time point. METHODS: All the rats were treated with bilateral oophorectomy 2 weeks before the experiment. T10 vertebral lamina was revolved into using plastic screw. The spinal canal impingement was not induced initially. After that, the original incision was opened to expose the screw every 7–10 days. MAIN OUTCOME MEASURES: The apoptosis and Caspase-3 positive cells in the damaged spinal cord were detected using terminal deoxynucleotidal transferase-mediated dUTP-biotin nick end labeling (TUNEL) method and Caspase-3 immunohistochemical staining at 1, 3, 7, 14, 28 and 60 days after chronic spinal cord injury respectively. RESULTS: Totally 65 rats were used, and the deleted ones during the experiment were supplemented by others. Changes of Caspase-3 expression after spinal cord injury: In the sham-operated group, only a small amount of Caspase-3 proteins were observed in the rat spinal cord, mainly located in motor neurons of spinal cord anterior horn. In the estrogen-treated group and saline control group, positive cells expressed occasionally at 1 day postoperatively, began to increase obviously at 7 days after injury, strongly expressed at 14 and 28 days, but decreased at 60 days, mainly located in the neurons of spinal cord gray matter anterior horn, and they expressed fewer in the motor neurons and white matter of ventral horn, and there were obvious differences between the estrogen-treated group and saline control group at 7, 14, 28 and 60 days (P < 0.05). CONCLUSION: Estrogen can reduce the apoptosis of nerve cells and promote the recovery of neurological function following gradual chronic spinal cord injury.     

Senegenin inhibits neuronal apoptosis after spinal cord contusion injury

Senegenin has been shown to inhibit neuronal apoptosis, thereby exerting a neuroprotective effect. In the present study, we established a rat model of spinal cord contusion injury using the modiifed Allen’s method. Three hours after injury, senegenin (30 mg/g) was injected into the tail vein for 3 consecutive days. Senegenin reduced the size of syringomyelic cavities, and it substantially reduced the number of apop-totic cells in the spinal cord. At the site of injury, Bax and Caspase-3 mRNA and protein levels were decreased by senegenin, while Bcl-2 mRNA and protein levels were increased. Nerve ifber density was increased in the spinal cord proximal to the brain, and hindlimb motor function and electrophysiological properties of rat hindlimb were improved. Taken together, our results suggest that senegenin exerts a neuroprotective effect by suppressing neuronal apoptosis at the site of spinal cord injury.     

Mechanisms underlying the promotion of functional recovery by deferoxamine after spinal cord injury in rats

Deferoxamine, a clinically safe drug used for treating iron overload, also repairs spinal cord injury although the mechanism for this action remains unknown. Here, we determined whether deferoxamine was therapeutic in a rat model of spinal cord injury and explored potential mechanisms for this effect. Spinal cord injury was induced by impacting the spinal cord at the thoracic T10 vertebra level. One group of injured rats received deferoxamine, a second injured group received saline, and a third group was sham operated. Both 2 days and 2 weeks after spinal cord injury, total iron ion levels and protein expression levels of the proinflammatory cytokines tumor necrosis factor-α and interleukin-1β and the pro-apoptotic protein caspase-3 in the spinal cords of the injured deferoxamine-treated rats were significantly lower than those in the injured saline-treated group. The percentage of the area positive for glial fibrillary acidic protein immunoreactivity and the number of terminal deoxynucleotidyl transferase d UTP nick end labeling-positive cells were also significantly decreased both 2 days and 2 weeks post injury, while the number of Neu N-positive cells and the percentage of the area positive for the oligodendrocyte marker CNPase were increased in the injured deferoxamine-treated rats. At 14–56 days post injury, hind limb motor function in the deferoxamine-treated rats was superior to that in the saline-treated rats. These results suggest that deferoxamine decreases total iron ion, tumor necrosis factor-α, interleukin-1β, and caspase-3 expression levels after spinal cord injury and inhibits apoptosis and glial scar formation to promote motor function recovery.     

Glial fibrillary acidic protein levels are associated with global histone H4 acetylation after spinal cord injury in rats

Emerging evidence has suggested global histone H4 acetylation status plays an important role in neural plasticity. For instance, the imbalance of this epigenetic marker has been hypothesized as a key factor for the development and progression of several neurological diseases. Likewise, astrocytic reactivity-a wellknown process that markedly influences the tissue remodeling after a central nervous system injury-is crucial for tissue remodeling after spinal cord injury(SCI). However, the linkage between the above-mentioned mechanisms after SCI remains poorly understood. We sought to investigate the relation between both glial fibrillary acidic protein(GFAP) and S100 calcium-binding protein B(S100B)(astrocytic reactivity classical markers) and global histone H4 acetylation levels. Sixty-one male Wistar rats(aged ~3 months) were divided into the following groups: sham; 6 hours post-SCI; 24 hours post-SCI; 48 hours post-SCI; 72 hours post-SCI; and 7 days post-SCI. The results suggested that GFAP, but not S100B was associated with global histone H4 acetylation levels. Moreover, global histone H4 acetylation levels exhibited a complex pattern after SCI, encompassing at least three clearly defined phases(first phase: no changes in the 6, 24 and 48 hours post-SCI groups; second phase: increased levels in the 72 hours post-SCI group; and a third phase: return to levels similar to control in the 7 days post-SCI group). Overall, these findings suggest global H4 acetylation levels exhibit distinct patterns of expression during the first week post-SCI, which may be associated with GFAP levels in the perilesional tissue. Current data encourage studies using H4 acetylation as a possible biomarker for tissue remodeling after spinal cord injury.     

Changes of Fas and Fas ligand immunoreactivity after compression trauma to rat spinal cord

This immunohistochemical study evaluated Fas and Fas ligand (FasL) in the rat nervous system and their changes in the spinal cord subjected to compression. Normal spinal cord showed a low level of Fas and FasL immunoreactivity in the white matter except in the corticospinal tracts. Fas and FasL immunoreactivity seemed to be located in axons and their myelin sheaths. Other regions of the nervous system did not show immunoreactivity to Fas and FasL. Moderate and severe compression injury of the spinal cord resulted in a reduction of Fas and FasL immunoreactivity in the white matter of injured T8–9 segments at 4 h and a complete loss at 1 day after trauma. This was seen even in the remaining white matter. In contrast, increased immunoreactivity to Fas and FasL was present in the cranial T7, caudal T10 (moderate injury) and T12 (severe injury) segments at day 4 with most intense staining were seen at day 9 after trauma. Increased Fas and FasL immunoreactivity may have pathophysiological implications for the development of secondary injuries after trauma to the spinal cord. Fas-FasL interactions may for instance be involved in apoptosis of oligodendrocytes which occurs as a delayed phenomenon after trauma to the spinal cord. The integrity of myelin sheaths may in this way be jeopardized by apoptosis of oligodendrocytes. Received: 30 June 1999 / Revised: 8 October 1999 / Accepted: 12 October 1999     

Hyperbaric oxygen therapy improves local microenvironment after spinal cord injury

Clinical studies have shown that hyperbaric oxygen therapy improves motor function in patients with spinal cord injury. In the present study, we explored the mechanisms associated with the recovery of neurological function after hyperbaric oxygen therapy in a rat model of spinal cord injury. We established an acute spinal cord injury model using a modification of the free-falling object method, and treated the animals with oxygen at 0.2 MPa for 45 minutes, 4 hours after injury. The treatment was administered four times per day, for 3 days. Compared with model rats that did not receive the treatment, rats exposed to hyperbaric oxygen had fewer apoptotic cells in spinal cord tissue, lower expression levels of aquaporin 4/9 mRNA and protein, and more NF-200 positive nerve fibers. Furthermore, they had smaller spinal cord cavities, rapid recovery of somatosensory and motor evoked potentials, and notably better recovery of hindlimb motor function than model rats. Our findings indicate that hyperbaric oxygen therapy reduces apoptosis, downregulates aquaporin 4/9 mRNA and protein expression in injured spinal cord tissue, improves the local microenvironment for nerve regeneration, and protects and repairs the spinal cord after injury.     

Protective effects and anti-apoptotic role of nerve growth factor on spinal cord neurons in sciatic nerve-injured rats

Abstract

Objectives:

The purpose of this study is to demonstrate a dependence of spinal cord motoneurons on the communication with their targets, sciatic nerves, and investigate whether the effects of nerve growth factor (NGF) on the spinal cord neuron apoptosis and surviving through the regulation of nuclear factor-kappa B (NF-kappaB) in Schwann cells (SCs) in sciatic nerve injured rats.

Methods:

Ninety healthy adult Sprague–Dawley rats were divided randomly into normal control group, crushing group, and NGF-intervened group. When sciatic nerve crushed 1, 3, 7, 14, and 21 days, the expression of NF-kappaB in SCs and the apoptosis regulator Bcl-2 and Caspase-3 in spinal cord were examined by immunohistochemistry staining, Western blot analysis, and immunofluorescence double-labeling method, the motor neuron apoptosis were investigated by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and the surviving neurons were tested by toluidine blue (Nissl) staining, respectively. All the data were further analyzed with SPSS10·0 application software.

Results:

The level of the expression of NF-kappaB in crushing group enhanced at 1 day after crushing, reached peak at 3 days, and reduced at least until 21 days, which was markedly higher than that in the normal control group. The expression of NF-kappaB in NGF-intervened group showed the same changes, reached peak at 7 days, and reduced until 21 days. However, when compared with crushing group, the expression of NF-kappaB in NGF-intervened group was down-regulated significantly until 3 days after injury, and up-regulated obviously with time going on. The same trend was observed in the time course on motor neuron apoptosis in crushing group and NGF-intervened group after sciatic nerves injury, while the reversing change was found in the surviving neurons. Moreover, the kinetics of Bcl-2 expression in spinal cord was consistent with that of NF-kappaB, while reversing with that of Caspase-3.

Conclusion:

The findings revealed that NGF may play a pivotal role of anti-apoptosis in spinal cord neurons through retrograde transport of NF-kappaB in SCs following sciatic nerve injury in rats.