维生素E对Alzheimer病模型大鼠的影响

采用ＡｌＣｌ３诱导，建立Ａｌｚｈｅｉｍｅｒ病（ＡＤ）模型大鼠。用维生素Ｅ（ＶＥ）（５ｍｇ／１００ｇ体重·ｄ－１）对ＡＤ模型大鼠进行灌胃治疗。通过行为测试，光镜形态学观察，用免疫细胞化学ＡＢＣ结合图像定量分析的方法，对ＡＤ大鼠行为改变，海马结构ＣＡ１区淀粉样蛋白免疫反应阳性神经元的形态和数目、胞体平均截面积和光密度以及β淀粉样蛋白的沉积变化进行观察。结果显示ＶＥ组大鼠治疗３个月和５个月后，受电击次数和潜伏期较对照组明显减少和延长（Ｐ＜００１），３个月与５个月之间有显著性差异（Ｐ＜００１）；ＶＥ组大鼠海马结构ＣＡ１区淀粉样蛋白免疫反应阳性神经元的形态和数目、胞体平均截面积和光密度值，３个月和５个月较对照组均有明显减少和降低（Ｐ＜００１），３个月和５个月之间也有显著性差异（Ｐ＜００１），β淀粉样蛋白样反应染色减少或消失。说明ＶＥ可以改善ＡＤ模型大鼠的学习记忆，其作用机制是通过抑制和清除海马结构ＣＡ１区β淀粉样蛋白的沉积来实现的，作用效果随治疗时间的延长而更加明显。本实验研究结果为临床应用ＶＥ治疗老年性痴呆提供了形态学依据。     

下丘脑室周核内生长抑素能神经元的衰老变化及何首乌的抗衰老作用

目的探讨下丘脑室周核内生长抑素（ＳＳＴ）能神经元胞体的衰老变化，并为何首乌的抗衰老作用提供一些形态学证据。方法采用Ｗｉｓｔａｒ雄性大鼠２０只，对照组分３、１２、２４月龄３组，每组各５只，普食喂养；喂药组采用１２月龄大鼠５只，以０．２５ｇ／ｋｇ的何首乌粉拌食喂养至２４月龄。以上各组均在同等条件下进行ＡＢＣ免疫组织化学实验和图像定量分析。结果对照组中，与３月龄大鼠对比，室周核内ＳＳＴ能神经元的细胞数在１２月龄出现减少（Ｐ值＜０．０５），２４月龄显著减少（Ｐ值＜０．０１）；灰度值随增龄而显著减少（Ｐ值＜０．０１）；细胞面积在１２月龄呈现增大（Ｐ值＜０．０１），２４月龄又趋向缩小（Ｐ值＜０．０５）。何首乌组与对照组同月龄大鼠相比，ＳＳＴ能神经元细胞数的减少程度及灰度值的减少程度均减轻（Ｐ值＜０．０１），细胞面积的缩小程度也减轻（Ｐ值＜０．０５）。结论室周核内ＳＳＴ能神经元随增龄呈现细胞数及灰度值的显著减少。从形态学上看，何首乌可能具有抗衰老作用。     

小鼠大脑皮质和海马结构内胆碱能纤维的分布及增龄变化

用乙酰胆碱酯酶（ＡＣｈＥ）组织化学方法和体视学测量技术，研究胆碱能纤维在小鼠大脑皮质和海马结构内的分布及增龄变化。结果显示，小鼠大脑皮质和海马结构内ＡＣｈＥ阳性纤维呈不同的板层样分布，老年小鼠（２４月龄）额－顶皮质第Ⅲ、Ⅴ层和海马ＣＡ１、ＣＡ３区分子层及齿状回分子层ＡＣｈＥ阳性纤维密度明显低于成年小鼠（１３月龄）和青年小鼠（３月龄）（Ｐ＜０．０１），后两组间除成年小鼠海马ＣＡ３区分子层纤维密度稍低外，其他各区无显著差异（Ｐ＞０．０５）。结果表明，胆碱能纤维在小鼠大脑皮质和海马结构内的分布具有年龄相关性和区域特异性。     

续断对Alzheimer病模型大鼠海马结构淀粉样沉积的影响

目的探讨续断抗衰老作用的机理。方法用续断（２ｇ／ｄ／只）对ＡＤ模型大鼠灌胃治疗３个月。通过行为测试,光镜免疫细胞化学ＡＢＣ法,对ＡＤ大鼠行为改变,海马结构齿状回和ＣＡ１区ＡＰ－Ｌｉ神经元的形态和数目,β－ＡＰ的沉积变化进行了观察。结果续断组大鼠较对照组受电击次数减少,潜伏期延长（Ｐ＜０．０１）,海马结构齿状回和ＣＡ１区ＡＰ－Ｌｉ神经元的数目较对照组均有明显减少（Ｐ＜０．０１）,β－ＡＰ样反应染色减少。结论续断可以恢复ＡＤ模型大鼠的学习记忆缺损,有抑制和清除海马结构齿状回和ＣＡ１区β－ＡＰ的沉积的作用。     

维生素E抑制痴呆模型大鼠海马结构淀粉样前体蛋白表达的实验研究

目的观察ＶＥ对ＡＤ大鼠海马β－ＡＰＰ表达的影响。方法使用三氯化铝诱导建立ＡＤ模型大鼠。用ＶＥ（１０ｍｇ／ｄ／只）对ＡＤ模型大鼠进行灌胃治疗３月。采用行为测试,光镜免疫细胞化学ＡＢＣ法,观测大鼠海马结构淀粉样前体蛋白反应阳性神经元的数目和β－淀粉样前体蛋白表达的变化。结果ＶＥ组大鼠受电击次数和潜伏期较对照组明显减少和延长（Ｐ＜０．０５）;ＶＥ组大鼠海马结构齿状回和ＣＡ１区淀粉样蛋白反应阳性神经元的数目较对照组均有明显减少（Ｐ＜０．０５）,β－淀粉样前体蛋白呈弱阳性表达。结论ＶＥ可以改善ＡＤ模型大鼠的学习记忆,降低海马结构β－淀粉样前体蛋白过度表达。     

药物诱发大鼠痴呆模型的初步研究

目的　建立一种模拟痴呆动物模型的制备方法。方法　按二水平三因素 Ｌ１６ （２１５ ）正交试验设计分组,应用 Ａ 因素（东莨菪碱）、 Ｂ 因素（氯胺酮）、 Ｃ 因素（ Ｄ半乳糖）皮下注射制备动物模型。利用 Ｍ Ｇ２ 迷宫检测大鼠学习记忆功能。通过组织病理学观察大鼠海马 Ｃ Ａ １ 区锥体细胞的数量和形态及神经元纤维缠结和老年斑等。结果　氯胺酮和 Ｄ 半乳糖分别可致大鼠记忆功能明显下降（ Ｐ ＜ ００５）和海马 Ｃ Ａ １ 区锥体细胞减少,并可见嗜神经细胞现象和胶质细胞小结。结论　大鼠注射氯胺酮或 Ｄ半乳糖可作为模拟痴呆模型的方法之一。     

衰老和缺锌大鼠海马胆囊收缩素神经元数目及免疫反应强度的…

选用Ｗｉｓｔａｒ雄性大鼠２４只，分为缺Ｚｎ组（７月龄）、老龄组（２８月龄）和对照组（７月龄），每组各８只。采用免疫组化ＡＢＣ结合图象分析，观察海马胆囊收缩素（ＣＣＫ）神经数目及其免疫反应强度的变化。结果表明，与对照组相比，缺Ｚｎ大鼠与老龄大鼠海马ＣＣＫ阳性神经元的数目和免疫反应强度均明显降低（Ｐ〈０．０５或Ｐ〈０．０１）。提示衰老过程中海马ＣＣＫ阳性神经元的数目减少，ＣＣＫ免疫反应强度降低；衰老过     

肾血管性高血压大鼠运动区NPY阳性神经元的变化

目的：研究肾血管性高血压大鼠运动区 Ｎ Ｐ Ｙ阳性神经元的变化。　方法：雄性 Ｓ Ｄ大鼠 ６０ 只，随机分为两组（ｎ＝ ３０）。手术组用单夹肾动脉法复制高血压模型，对照组手术过程同手术组，但不上银夹。于术后 ７ ｄ，３０ ｄ，９０ ｄ 处死动物，取脑，用 Ａ Ｂ Ｃ免疫组化方法对大鼠运动区 Ｎ Ｐ Ｙ 阳性神经元进行定量分析。　结果：对照组运动区 Ｎ Ｐ Ｙ阳性神经元密度随年龄增加而减少，而手术组 Ｎ Ｐ Ｙ阳性神经元密度先减少，后增加，最后保持不变。手术组和对照组 Ｎ Ｐ Ｙ 神经元密度相比，术后 ７ ｄ 两组间无显著差异；术后 ３０ ｄ 手术组小于对照组（ Ｐ＜ ０．０５）；术后 ９０ ｄ 手术组大于对照组（ Ｐ＜ ０．０１）。　结论： Ｎ Ｐ Ｙ阳性神经元在高血压的发生、发展过程中起一定调控作用。     

衰老和缺锌大鼠海马胆囊收缩素神经元数目及免疫反应强度的变化

选用Ｗｉｓｔａｒ雄性大鼠２４只，分为缺Ｚｎ组（７月龄）、老龄组（２８月龄）和对照组（７月龄），每组各８只。采用免疫组化ＡＢＣ法结合图象分析，观察海马胆囊收缩素（ＣＣＫ）神经数目及其免疫反应强度的变化。结果表明，与对照组相比，缺Ｚｎ大鼠与老龄大鼠海马ＣＣＫ阳性神经元的数目和免疫反应强度均明显降低（Ｐ＜０．０５或Ｐ＜０．０１）。提示衰老过程中海马ＣＣＫ阳性神经元的数目减少，ＣＣＫ免疫反应强度降低；衰老过程中机体Ｚｎ水平的降低是触发这种变化的重要原因之一。     

维生素对Alzheimer病模型大鼠的影响

采用ＡｌＣｌ３诱导，建立Ａｌｚｈｅｉｍｅｒ病（ＡＤ）模型大鼠。用维生素Ｅ（ＶＥ）对ＡＤ模型大鼠进行灌胃治疗。通过行为测试，光镜形态学观察，用免疫细胞化学ＡＢＣ结合图像定量分析的方法，对ＡＤ大鼠行为改变，海马结构ＣＡ１区淀粉样蛋白免疫反应阳性神经元的形态和数目、胞体平均截面积和光密度以及β－淀粉样蛋白的沉积变化进行观察。结果显示ＶＥ组大鼠治疗３个月和５个月后，受电击次数和潜伏期罗对照组明显减少和延长     

Neurobiology of the aging brain: morphological alterations at synaptic regions

Computer-assisted morphometric studies have been carried out on nerve cell terminal regions in rats of different ages. The numerical density (Nv), the average area (S) and the surface density (Sv) of ethanol phosphotungstic acid stained (E-PTA) synaptic junctions were evaluated in cerebellar glomeruli and dentate gyrus supragranular layers. The volume density (Vv), the average volume (V) and the numerical density (Nvm) of synaptic mitochondria were measured in the cerebellar glomeruli of young (3 months), adult (11 months) and old (28 months) animals. We found that during aging Nv and Sv undergo a significant decrease, whereas S is significantly increased. The mitochondrial Vv is unchanged in all the age groups analysed, whereas in old rats V is increased and Nvm decreased, respectively. We interpret our results as supporting that the old CNS retains part of its remodelling activity and is capable of adaptive morphological response at synaptic terminal regions.     

不同月龄大鼠大脑中低密度脂蛋白受体相关蛋白的表达

目的　探讨不同月龄大鼠大脑额叶、海马、纹状体低密度脂蛋白受体相关蛋白 (LRP 1)表达的变化。方法　雄性SD大鼠 15只 ,流式细胞技术检测并计算 1,3,10月龄大鼠大脑额叶、海马、纹状体匀浆单细胞悬液LRP 1表达的平均荧光指数 ;免疫组织化学技术测定大脑海马CA1区神经细胞、微血管LRP 1表达 ,并应用MIAS图像分析系统进行平均吸光度测定。结果　流式细胞研究显示 ,大鼠海马 1、3月龄LRP 1表达强度均显著高于 10月龄大鼠 ;而额叶及纹状体各月龄组间差异无显著性意义。 1、3月龄大鼠海马区LRP 1表达强度均显著高于额叶及纹状体。免疫组织化学结果显示 ,LRP 1在海马CA1区微血管、神经细胞均有表达。随着月龄的增加 ,LRP 1在微血管的表达显著下降 ,而在海马CA1区神经细胞的表达各月龄组差异无显著性意义。结论　随着月龄的增加 ,海马区LRP 1的表达有下降趋势 ,尤其是海马CA1区微血管LRP 1的表达显著下降。     

Ⅱ组代谢型谷氨酸受体阻断剂对大鼠海马神经元凋亡的影响

目的观察Ⅱ组代谢型谷氨酸受体阻断剂对大鼠海马神经元凋亡的影响。方法 SD大鼠24只随机分为假手术组、痴呆组和阻断剂组,每组8只。大鼠脑室注射凝聚肽Aβ_(25-35)5建立痴呆大鼠模型,阻断剂组1周后行阻断剂脑室注射,另2组等量注射人工脑脊液4周行Morris水迷宫测试;测试1周后取材行病理观察,采用TUNEL法检测海马CA1区锥体细胞凋亡情况。结果与假手术组比较,痴呆组大鼠平均潜伏期明显延长,平台象限滞留时间明显缩短(P0.05);与痴呆组比较,阻断剂组大鼠上述指标明显提高(P0.05)。与假手术组比较,痴呆组大鼠海马CA1区可见大量的凋亡锥体细胞,阳性锥体细胞数、总面积、平均吸光度(A)值明显升高(P0.05);与痴呆组比较,阻断剂组大鼠海马CA1区可见明显的阳性细胞和核固缩,但其阳性染色锥体细胞数、总面积、平均A值明显降低(P0.05)。结论Ⅱ组代谢型谷氨酸受体阻断剂可明显抑制痴呆引起的海马CA1区锥体细胞的凋亡,提示其可能通过影响细胞凋亡,参与痴呆的发病过程。     

缺锌对衰老大鼠海马精氨酸加压素水平的影响

采用Y－迷宫实验、放射免疫分析和原子吸收分光光反法，测定缺锌、衰老和正常Wistar大鼠学习记忆行为、海马AVP水平和血浆Zn含量变化。结果：与对照组相比，老龄和缺锌大鼠在Y－迷宫中达到学会标准所需的潜伏期或次数明显延长（P＜0．05），血浆Zn和海马AVP水平明显降低（P＜0．05或P＜0.01）．提示表老过程中海马AVP水平明显降低，触发这种变化的原因可能与衰老过程中机体Zn水平的降低有关。     

下丘脑室周核内生长抑素神经元的衰老变化及牛膝抗衰老作用的实验研究

采用免疫组织化学ＡＢＣ法结合图象定量分析观察下丘脑室周核内生长抑素（ＳＯＭ）神经元的衰老变化及牛膝的抗衰老作用。结果表明：室周核内ＳＯＭ神经元的细胞数和灰度值呈增龄性降低；细胞面积在９月龄呈现增大，２２月龄又趋向缩小．牛膝喂药组与同月龄大鼠相比，ＳＯＭ神经元的细胞数减少及灰度值的减少均降低，细胞面积相对较大。本实验从形态学上报示牛膝具有延缓衰老之功效。     

鼠肝老化进程中枯否细胞对肝细胞的影响及机制

目的研究肝脏老化时枯否细胞（ＫＣ）在肝细胞（ＨＣ）功能损害中的地位和机制．方法应用ＨＣＫＣ共同培养技术研究６，１２，１８和２４月龄大鼠（每组５只）ＫＣ对ＨＣ蛋白质合成和线粒体代谢水平的影响，并探讨了这种影响与老化ＫＣ分泌功能改变的关系．结果单独培养的２４月龄组ＨＣ蛋白质合成能力和线粒体代谢水平较６月龄组明显降低；各月龄组ＨＣ与６月龄组ＫＣ共同培养时，两指标较单独培养者均有明显增加，与２４月龄组ＫＣ共同培养时则显著降低．ＬＰＳ（１０ｎｇ／Ｌ）对单独培养的ＨＣ蛋白质合成和线粒体能量代谢无明显影响，但对共同培养系统中６月龄ＫＣ的增强作用和２４月龄ＫＣ的抑制作用具有明显的放大作用．２４月龄组ＫＣＴＮＦ、ＩＬ８、ＮＯ的分泌水平较６月龄组ＫＣ明显升高，ＰＧＥ２明显降低．各组ＫＣ受ＬＰＳ刺激后ＴＮＦ和ＮＯ水平较未刺激组均有明显升高，其增值以高月龄组为显著；６和１２月龄组ＫＣ受刺激后ＩＬ８水平明显升高，１８和２４月龄组无明显变化；ＰＧＥ２的变化规律与ＩＬ８相反．结论ＫＣ在鼠肝老化时ＨＣ受损过程中起重要作用，这可能与老化ＫＣ分泌细胞因子谱有改变，导致ＨＣ分子微生态环境变化有关．     

Morphometric characterization of left ventricular myocardial cells of male rats during postnatal development.

Morphometric investigations of the left ventricular myocardial cells of male Wistar rats aged 0, 1, 2, 3, 4, 5, 6, 7, 14, 21 days and 1, 2, 3, 4, 5, 6 months were carried out.The volume density of the sarcoplasm decreased from 0.33 (at birth) to 0.018 (6th month). The volume density of the myofibrils diminished during the first 7 days of life, whereas after the 6th month (0.57) it was nearly the same again as at birth (0.52). The volume density of the mitochondria increased from 0.16 at birth to 0.33 in the 6th month. The surface density of the outer mitochondrial membrane increased at different rates. The number of mitochondria per unit area grew from 0.51 (at birth) to 0.88 (6th month). The distance between the mitochondria decreased from 4.33 μm (at birth) to 1.67 μm (6th month). The mitochondrial/myofibrillar ratio doubled in the course of the period covered by the study (0.32 at birth; 0.64 in the 6th month).The postnatal development of heart muscle cells can be characterized by data obtained on the heart at birth, at the ages of 3, 4, 5, 7, and 14 days and in the 1st, 3rd and 6th month.     

慢性氟中毒对大鼠大脑皮质神经细胞活性氧水平和线粒体融合的影响

目的 观察慢性氟中毒对大鼠大脑皮质神经细胞活性氧(ROS)水平和线粒体融合的影响,并分析二者间的关系.方法 选择SD大鼠120只,按性别和体质量随机分为3组:对照组、低氟组、高氟组,每组40只.对照组大鼠自由饮用自来水(含氟量<0.5 mg/L);低、高氟组分别饮用氟化钠(NaF)配制的含氟量为10.0、50.0 mg/L的自来水.分别于3、6个月时处死大鼠,采集大脑组织制作冰冻切片,采用荧光测定法检测皮质神经细胞ROS水平和线粒体形态变化.结果 3、6个月时各组大鼠大脑皮质神经细胞ROS荧光计数和Ⅱ型线粒体计数水平比较,差异有统计学意义(F值分别为3.07、3.06,3.05、3.07,P均<0.05).3个月时,与对照组(10.43±5.98、4.12±3.86)比较,高氟组大鼠大脑皮质神经细胞ROS荧光计数(25.48±6.09)和Ⅱ型线粒体计数(20.47±6.09)明显升高(P均<0.05),而低氟组(11.67±3.49、6.68±3.48)未见明显改变(P均>0.05);6个月时,与对照组(25.26±6.41、20.26±6.41)比较,低、高氟组大鼠大脑皮质神经细胞ROS荧光计数和Ⅱ型线粒体计数(63.02±8.15、65.60±7.40,49.33±8.61、53.10±6.95)均明显增高(P均<0.05).ROS荧光计数与Ⅱ型线粒体计数间呈明显正相关(r值分别为0.93、0.81,P均<0.05).结论 摄入过量的氟导致大鼠大脑皮质神经细胞氧化应激水平升高,线粒体融合功能障碍,这些改变与染氟时间和剂量密切相关.线粒体异常改变的机制可能与慢性氟中毒引起的氧化应激水平升高有关.

Abstract：

Objective To investigate the changes of reactive oxygen species(ROS) level and mitochondria fission-fusion-balance in cortical neurons of rats with chronic fluorosis and reveal the correlation between these two factors. Methods One hundred and twenty rats were randomly divided into 3 groups(control group, low-dose fluorosis group, high-dose fluorosis group) and 40 rats were in each group according to body weight and the experiments were carried out for 3 months or 6 months. The rats were fed with different concentrations of fluoride (NaF) to establish fluorosis models. Controls were fed with tap water( < 0.5 mg/L), experimental animals in low- or high-dose group were fed with water containing NaF 10.0,50.0 mg/L, respectively. The level of ROS and the morphology in mitochondria fission-fusion balance in neurons of the cortex of rat brains prepared with cortical frozen sections were detected with ROS fluorescent probe and MitoTracker RED probe, respectively. Results Significant differences of the level of ROS and the numbers of abnormal mitochondria in morphology in the cortical neurons were found between 3 groups at the experiment period of 3 month and 6 month(F= 3.07,3.06,3.05,3.07, all P < 0.05). As compared with control group(10.43 ± 5.98,4.12 ± 3.86) at the experiment period of 3 month, the level of ROS and the numbers of abnormal mitochondria in morphology in the cortical neurons were obviously increased in high-dose fluorosis group(25.48 ± 6.09,20.47 ± 6.09, all P < 0.05), whereas no significant changes were found in low-dose fluorosis group(11.67 ± 3.49,6.68 ± 3.48, all P> 0.05). Furthermore, the increases in both ROS level and abnormal numbers of mitochondria were significant observed in the cortical neurons of low-dose fluorosis group (63.02 ± 8.15, 49.33 ± 8.61) and high-dose fluorosis group(65.60 ± 7.40,53.10 ± 6.95) as compared with the control group (25.26 ± 6.41,20.26 ± 6.41) at the experimental period of 6 month (all P < 0.05). The abnormal numbers of mitochondria correlated with ROS level(r = 0.93,0.81, all P < 0.05). Conclusions Taking excessive amount of fluoride results in high level of oxidative stress and impaired the balance of mitochondrial fission-fusion,which is dependent on the feeding times and doses of fluoride. The mechanism of the mitochondrial abnormalities might be associated with the high level of oxidative stress induced by chronic fluorosis.     

褪黑素通过沉默信息调节因子1减轻线粒体氧化应激对脑缺血-再灌注小鼠的作用

目的探讨褪黑素通过沉默信息调节因子1(SIRT1)减轻线粒体氧化应激机制对脑缺血-再灌注(IR)小鼠的作用。方法通过线栓法建立小鼠短暂性大脑中动脉阻塞(MCAO)IR模型,对190只小鼠经腹腔注射褪黑素和侧脑室注射SIRT1抑制剂EX527,剔除死亡小鼠30只,按随机数字表法分为IR组、褪黑素组、褪黑素+EX527组、EX527组各40只,通过2,3,5-氯化三苯基四氮唑(TTC)法测定脑梗死体积、干湿比重法测定脑水肿并进行神经功能缺损评分。通过Western blot检测线粒体和胞质SIRT1、Ac-P53、Ac-核因子κB(Ac-NF-κB)、BCL2、BAX蛋白以及细胞色素C蛋白表达。多组间比较采用单因素方差分析。结果 (1)4组间脑梗死体积、神经功能障碍评分和脑水肿的差异均有统计学意义(F值分别为16.452、23.622和18.786,均P0.05)。4组SITR1、Ac-P53、Ac-NF-κB、BCL2、BAX表达差异均有统计学意义(F值分别为2 348.158、1 434.841、7 042.563、14 627.128和691.475,均P0.05)。4组小鼠线粒体膜电位、线粒体活性氧和复合体Ⅰ活性差异有统计学意义(F值分别为28.454、33.728和29.716,均P0.05)。(2)与IR组相比,褪黑素组的脑梗死体积缩小(32±5)mm~3比(57±5)mm~3,P0.05);神经功能障碍评分降低(2.4±0.3比3.5±0.3,P0.05);脑水肿减轻(80.2±0.9)%比(83.9±1.2)%,P0.05);SIRT1和抗凋亡蛋白BCL2的表达增加(P0.05);促凋亡蛋白BAX和Ac-P53、Ac-NF-κB的表达减少(P0.05);线粒体膜电位、线粒体复合体Ⅰ活性和细胞色素C水平提高(P0.05);胞质活性氧产物和细胞色素C水平降低(P0.05)。(3)与褪黑素组相比,褪黑素+EX527组的脑梗死体积增大[(42±5)mm~3比(32±5)mm~3,P0.05];神经功能障碍评分增高(3.2±0.3比2.4±0.3,P0.05);脑水肿加重[(83.4±0.8)%比(80.2±0.9)%,P0.05];SIRT1和抗凋亡蛋白BCL2的表达减少(P0.05);促凋亡蛋白BAX和Ac-P53、Ac-NF-κB的表达增加(P0.05);线粒体膜电位、线粒体复合体Ⅰ活性和细胞色素C水平降低(P0.05);胞质活性氧产物和胞质细胞色素C水平提高(P0.05)。结论在缺血性卒中模型小鼠中,褪黑素通过激活SIRT1信号通路,减轻线粒体氧化应激损伤和细胞死亡,从而发挥脑保护作用。     

Synaptic remodeling in hippocampal CA1 region of aged rats correlates with better memory performance in passive avoidance test

Aging is associated with deficits in long-term declarative memory formation, and wide differences in performance can be observed among aged individuals. The cellular substrates of these deficits and the reasons for such marked individual differences are not yet fully understood. In the present study, morphologic parameters of synapses and synaptic mitochondria in stratum molecolare of CA1 hippocampal region were investigated in aged (26- to 27-month-old) female rats after a single trial inhibitory avoidance task. In this memory protocol animals learn to avoid a dark compartment in which they received a mild, inescapable foot shock. Rats were tested 3 and 6 or 9 hours after the training, divided into good and bad responders according to their performance (retention times above or below 100 seconds, respectively) and immediately sacrificed. The number of synapses and synaptic mitochondria per cubic micrometer of tissue (numeric density), the average area of synapses and volume of synaptic mitochondria, the total area of synapses per cubic micrometer of tissue, the percentage of perforated synapses and the overall volume of mitochondria per cubic micrometer of tissue were evaluated. In the good responder group, the numeric density of synapses and mitochondria was significantly higher and the average mitochondrial volume was significantly smaller 9 hours versus 6 hours after the training. No significant differences were observed among bad responders. Thus, better performances in passive avoidance memory task are correlated with more efficient plastic remodeling of synaptic contacts and mitochondria in hippocampal CA1. Present findings indicate that maintenance of synaptic plastic reactivity during aging is a critical requirement for preserving long-term memory consolidation.