小鼠海马结构与脊髓损伤后抑郁症高发病率的关系研究

目的:探究脊髓损伤引发的抑郁高风险率是否与海马生理结构的改变有关。方法:制作小鼠脊髓损伤模型,分别在损伤后不同时期采用Basso Mouse Scale(BMS)评分对小鼠术后运动功能进行评估;并通过糖水偏好实验和悬尾实验评估小鼠的抑郁情况;HE染色观察海马组织内部细胞的变化;电镜观察海马亚细胞结构突触的结构变化;RT-qPCR检测突触蛋白标志物突触小泡蛋白(SYP)和突触后致密蛋白95(PSD-95)在mRNA水平上的变化。结果:行为学实验显示模型组小鼠有显著的抑郁行为,且在第7天抑郁程度最显著(P<0.01);HE染色显示,与对照组相比,模型组海马细胞排列紊乱,数量减少,形态欠规则;电镜结果显示,与对照组相比,模型组海马超微结构突触数量减少,突触活动区长度变短,突触后致密物厚度变薄,突触间隙宽度增加,突触界面曲率减小(P<0.05);RT-qPCR结果显示模型组SYP和PSD-95 mRNA表达水平较对照组降低(P<0.05)。结论:海马生理结构的改变是脊髓损伤后抑郁症高风险的原因之一。     

The relationship between age-related hearing loss and synaptic changes in the hippocampus of C57BL/6J mice

To explore the relationship between age-related hearing loss (presbycusis) and synaptic degeneration in the hippocampal CA3 region of C57BL/6J mice, we investigated both cognitive performance and synaptic changes within the hippocampus of C57BL/6J mice from three age groups of 6-8, 24-26, and 42-44 weeks; CBA/CaJ mice served as controls. The auditory brainstem response was used as a measure of hearing threshold, and cognitive behavior was evaluated using the Morris water maze. The ultrastructure of synapses was observed with transmission electron microscopy, and the quantity and distribution of the synaptic markers synaptophysin and PSD-95 were observed with immunohistochemistry. The hearing threshold of C57BL/6J mice was significantly higher at 24-26 weeks than at 6-8 weeks, and hearing loss was profound at 42-44 weeks. This was accompanied by progressive degeneration of synapses within the auditory cortex. In contrast, the hearing threshold of CBA/CaJ mice was relatively unchanged at 24-26 weeks of age, and these mice developed only mild hearing loss at 42-44 weeks of age. Interestingly, C57BL/6J, but not CBA/CaJ mice clearly exhibited both decreased performance in the Morris water maze and degeneration of synapses within the hippocampus. We therefore conclude that age-related hearing loss is accompanied by the degeneration of synapses in the hippocampal CA3 region of C57BL/6J mice.     

Glutaminase1 heterozygous mice show enhanced trace fear conditioning and Arc/Arg3.1 expression in hippocampus and cingulate cortex

Mice heterozygous for a mutation in the glutaminase (GLS1) gene (GLS1 HZ mice), with reduced glutamate recycling and release, display reduced hippocampal function as well as memory of contextual cues in a delay fear conditioning (FC) paradigm. Here, we asked whether this deficit reflects an inability to process contextual information or a selective alteration in salience attribution. In addition, we asked whether baseline and activity-induced hippocampal activity were diminished in GLS1 HZ mice. For this purpose, we manipulated the relative salience of the conditioned stimulus (CS) and contextual cues in FC tasks, and examined gene expression of the immediate early gene Arc (Arc/Arg3.1) in hippocampus and anterior cingulate cortex (ACC) following trace FC (tFC). The results indicate that GLS1 HZ mice succeed in processing contextual information when the salient CS is absent or less predictive. In addition, in the hippocampus-dependent tFC paradigm GLS1 HZ mice display enhanced CS learning. Furthermore, while baseline arc activation was reduced in GLS1 HZ mice in the hippocampus, in line with previous fMRI findings, it was enhanced in the hippocampus and anterior cingulate cortex following tFC. These findings suggest that GLS1 HZ mice have a pro-cognitive profile in the tFC paradigm, and this phenotype involves activation of both hippocampus and ACC.Taken together with previous work on the GLS1 HZ mouse, this study sheds light on the importance of glutamate transmission to memory processes that require the allocation of attentional resources, and extends our understanding of the underpinnings of attention deficits in SZ.     

七氟烷对新生大鼠海马Bcl-2表达及学习记忆能力的影响

目的：研究七氟烷对新生大鼠海马Bcl-2表达的影响,探讨其在神经细胞凋亡过程中的作用机制及相互作用方式。方法7日龄健康SD大鼠24只,体质量10～14 g ,雌雄不拘,使用随机数字表法将实验动物随机分为两组（n＝12）：A组为七氟烷组,B组为吸氧对照组。将A组急性暴露于2．3％七氟烷4h。暴露结束后等候4h。从两组大鼠中各取六只处死,取海马组织,用流式细胞术检测海马神经元凋亡,免疫印迹（Western Blot）法半定量检测Bcl-2的表达。剩余的12只饲养二周后做跳台试验。结果与吸氧对照组相比,七氟烷组海马神经元凋亡显著增加（ P＜0．05）。Western印迹法结果显示,七氟烷组Bcl-2表达降低。跳台试验证实大鼠学习记忆能力下降。结论七氟烷急性暴露可致发育中神经元的凋亡,导致认知功能障碍,其机制可能与Bcl-2信号通路有关。     

长期有氧运动和饮食铁含量对雌性大鼠血液铁和海马贮存铁的影响

目的观察饮食铁含量和长期有氧运动对雌性大鼠血液铁状态和海马非血红素铁（NHI）贮存的影响,探讨外周铁浓度与脑铁浓度的变化关系。方法采用断乳雌性SD大鼠71只,随机分为3组：饮食低铁含量组（12mg／kg）,饮食标准铁含量组（45mg／kg）和饮食高铁含量组（1000mg／kg）,其中每一组再分为运动组和静息组。用相应的铁含量饲料喂养1个月后,运动组进入游泳期,每周5d,每天1次,每次30min,持续3个月。静息组除不进行运动外,其余处理与对应运动组相同。在末次运动后,所有大鼠禁食24h,用戊巴比妥钠麻醉后静脉取血,测定红细胞相关指标和血清铁状态指标;断头取全脑,冰上快速分离出海马,测定海马NHI含量。结果与标准铁含量静息组比,低铁含量静息组血红蛋白（Hb）、红细胞压积（HCT）、平均红细胞体积（MCV）和平均红细胞血红蛋白量（MCH）均降低（P〈0．05）,红细胞分布宽度（RDW）和血浆总铁结合力（TIBC）升高（P〈0．05）。低铁含量饮食时（ID）,与静息组比,运动组Hb、HCT显著升高（P〈0．01）,海马NHI含量升高（P〈0．05）,血清铁（SI）、转铁蛋白饱和度（TS）均显著降低（P〈0．01）。高铁含量饮食时（SU）,与静息组比,运动组血浆TIBC升高（P〈0．05）,TS降低（P〈0．05）。结论低铁含量饮食导致雌性大鼠出现血液低铁状态,机体对于饮食铁不足有适应性调节;低铁饮食下长期低强度运动会加重雌性大鼠血液低铁状态,并且导致脑内海马铁贮存水平升高。     

充血性心力衰竭大鼠的大脑海马区TGF-β1表达的变化

目的研究充血性心力衰竭大鼠的大脑海马区TGF-β1变化。方法将85只成年雄性sD大鼠随机分为正常组5只、假手术组40只、模型组40只,假手术组和模型组观察时间点为术后1、2、4、8周。采用腹主动脉部分缩窄术。建立大鼠慢性充血性心力衰竭模型。应用超声心动图动态监测左室舒张末期内径（LVEDd）,舒张末期室间隔厚度（IVSd）和左室后壁厚度（LVPWd）;解剖心脏,计算心肌质量指数[心质量／体质量（HW／BW）和左室质量／体质量（LVW／BW）],免疫组织化学染色法检测大脑海马区TGF-β1表达变化。结果模型组LVEDd、IVSd、LVPWd高于正常组和假手术组,且呈时间依赖性上升趋势（P〈0．01）。模型组心肌质量指数与正常组和假手术组比较,差异有统计学意义（P〈0．01）。模型组TGF-β1表达量明显高于假手术组。结论压力超负荷性心力衰竭发生过程中大脑海马区TGF-β1表达量明显增高。     

肝性脑病大鼠海马CA3区神经元形态和一氧化氮合酶表达的变化

目的观察肝性脑病模型组和正常对照组大鼠脑海马CA3区神经元的变化及一氧化氮合酶(NOS)的表达;探讨海马CA3区神经元的形态学改变及一氧化氮(NO)在肝性脑病发病机制中的作用。方法雄性大鼠50只,实验开始前所有动物均进行莫里斯水迷宫测试,之后将动物分为对照组和实验组。9周后建立CCL4肝性脑病模型,分别取两组大鼠海马组织进行尼氏染色及烟酰胺腺嘌呤二核苷酸-黄递酶(NADPH-d),染色。结果尼氏染色发现,实验组大鼠海马神经元数目减少、染色较浅,胞质内尼氏体减少或消失;NADPH-d染色发现,实验组可见粗大轴突着色,树突联系广泛;对照组则少有粗大轴突着色,树突间联系不如实验组广泛。实验组NOS阳性神经元染色较对照组深,为紫蓝或深蓝色(强阳性及阳性),且阳性神经元数目较多;而对照组染色浅淡,呈浅蓝或与背景同色,为弱阳性。结论肝性脑病时海马受到损伤,NO可能介导了神经元的损伤并参与了肝硬化和肝性脑病的发病,血氨升高是肝性脑病(HE)致病因素之一。     

反复吸入七氟醚对大鼠海马和血小板线粒体功能的影响

目的探讨反复吸入七氟醚对成年大鼠海马和血小板线粒体功能的影响方法选取体质量250～300 g的雄性SD大鼠60只,随机分成3组,每组20只:空白对照组(Ⅰ组);单次吸醚组(Ⅱ组)。单次吸入浓度为2.4%七氟醚;反复吸醚组(Ⅲ组),连续5 d吸入浓度为2.4%七氟醚。每组随机取10只,测定海马和血小板线粒体的ATP的含量和SOD活力,另外10只予八臂迷宫行为学检测。结果单次或反复吸入2.4%七氟醚5 d后,与空白组相比,海马和血小板线粒体的ATP的含量和SOD活力,差异无统计学意义(P>0.05)。结论成年大鼠反复吸入2.4%七氟醚,对海马组织和血小板线粒体的SOD、ATP无明显影响,提示短期反复吸入七氟醚不会引起大鼠近期学习记忆功能损害。     

大鼠海马脑片缺血-再灌注模型中一氧化氮及一氧化氮合酶的变化

目的 建立器官型海马脑片缺血-再灌注模型,以阐明一氧化氮和一氧化氮合酶(NOS)在脑缺血-再灌注中的作用。 方法 以12只出生7-8 d的Sprague-Dawley乳鼠制备海马脑片,根据培养时间随机分为4组,每组2个微孔膜,每个Millcell-CM微孔膜放置6张脑片,在培养液和气体界面上培养脑片,4组中每组36张脑片。培养14 d后,缺氧、缺糖30 min,再灌注12、24和36 h,用逆转录聚合酶链反应(RT-PCR)和Western印迹技术,分别检测脑片组织中一氧化氮、NOS的mRNA和蛋白质水平的变化;用改良镉还原法检测培养液中一氧化氮代谢产物亚硝酸盐含量;生化法榆测培养液中乳酸脱氢酶(LDH)水平。 结果 缺血-再灌注模型的脑片组织,诱导性的一氧化氮合酶(iNOS)和神经源性的一氧化氮合酶(nNOS)在mRNA和蛋白质水平均表达上调,培养液中一氧化氮代谢产物亚硝酸盐含量明显高于对照组,差异有显著意义(P<0.05)。同时,培养液中LDH的水平随再灌注时间的延长而升高。结论 一氧化氮及NOS在脑缺血-再灌注损伤中起着重要作用。