T细胞转录因子-4在大鼠脑缺血再灌注海马齿状回神经干细胞中的表达

目的:检测T细胞转录因子-4(Tcf-4)在大鼠脑缺血再灌注海马组织神经干细胞中的表达及其变化。探讨影响神经干细胞早期增殖分化的分子调控机制。方法:采用大脑中动脉栓塞(MCAO)制作大鼠脑缺血再灌注模型。用免疫组织化学SP法及RT-PCR法检测海马神经干细胞BrdU、Tcf-4中的表达。结果:随着脑缺血再灌注第3日齿状回神经元BrdU阳性细胞明显增多,第7日达高峰,然后逐渐减少。Tcf-4 mRNA反应产物随脑缺血再灌注时间延长逐渐增多,第21日表达最强,以后表达逐渐减少。结论:Tcf-4时间依赖性表达与神经干细胞增殖分化进程相吻合,说明其在神经干细胞晚期分化中起重要调控作用。     

NMDA受体在β-淀粉样蛋白引起海马神经元突触蛋白改变中的作用

为了研究NMDA受体活性对Aβ引发的海马神经元突触蛋白表达变化的影响,本文运用免疫细胞化学方法检测不同浓度NMDA受体激动剂以及拮抗剂对Aβ诱导的海马神经元突触蛋白变化的影响。结果显示:NMDA可浓度依赖性地缓解Aβ25-35引起的突触蛋白synaptophysin与PSD-95的减少。抑制突触内NMDA受体,NMDA缓解Aβ减少突触蛋白的作用减弱;抑制突触外NMDA受体,对抗Aβ的作用无显著变化。本研究结果提示NMDA受体活性改变影响Aβ诱导的突触蛋白减少,突触内NMDA受体激活可对抗Aβ的毒性作用。突触内NMDA受体活性减弱可能在谷氨酸兴奋毒性中发挥作用。     

9602对脑缺血再灌大鼠海马CA1区诱发电位与形态学改变的影响

目的:探讨脑缺血再灌注后海马CA1区诱发群峰电位的变化与形态学改变的关系及中药9602的影响。方法:在整体脑缺血再灌注后不同时间制备的海马脑片上,记录CA1区诱发群峰电位(PS)的变化。采用TUNEL,Nissl染色法进行形态学检测。结果:脑缺血再灌组诱发PS的阈强度明显大于假手术组,波幅显著减小;加条件刺激后PS增幅显著低于假手术组,持续时间缩短。上述变化始于脑缺血再灌后8h,随再灌时间的延长而加重。海马CA1区再灌后8h起TUNEL阳性细胞明显增多,24h达高峰,异常细胞8h最多,随后降低并在低水平持续到7d,细胞总数随再灌时间的延长逐渐减少。中药9602明显降低缺血再灌脑片PS阈强度,增大PS波幅;加大条件刺激后PS增幅并延长持续时间;明显减少海马CA1区的TUNEL阳性细胞数,阻止CA1区细胞数的减少。结论:脑缺血再灌后海马CA1区神经细胞兴奋性和反应性降低,与脑缺血再灌后迟发性神经元死亡(DND)有关,细胞凋亡起重要作用。9602明显改善CA1区神经细胞的兴奋性和反应性,可能与其抑制脑缺血再灌诱导的细胞凋亡,减轻DND的发生有关。     

The ventral hippocampus and fear conditioning in rats. Different anterograde amnesias of fear after tetrodotoxin inactivation and infusion of the GABA(A) agonist muscimol

Studies on the involvement of the rat hippocampus in classical fear conditioning have focused mainly on the dorsal hippocampus and conditioning to a context. However, the ventral hippocampus has intimate connections with the amygdala and the nucleus accumbens, which are involved in classical fear conditioning to explicit and contextual cues. Consistently, a few recent lesion studies have indicated a role for the ventral hippocampus in classical fear conditioning to explicit and contextual cues. The present study examined whether neuronal activity within the ventral hippocampus is important for the formation of fear memory to explicit and contextual cues by classical fear conditioning. Tetrodotoxin (TTX; 10 ng/side), which completely blocks neuronal activity, or muscimol (1 microg/side), which increases GABA(A) receptor-mediated inhibition, were bilaterally infused into the ventral hippocampus of Wistar rats before the conditioning session of a classical fear-conditioning experiment. Conditioning to a tone and the context were assessed using freezing as a measure of conditioned fear. TTX blocked fear conditioning to both tone and context. Muscimol only blocked fear conditioning to the context. The data of the present study indicate that activity of neurons in the ventral hippocampus is necessary for the formation of fear memory to both explicit and contextual cues and that neurons in the ventral hippocampus that bear the GABA(A) receptor are important for the formation of fear conditioning to a context. In addition, both bilateral muscimol (0.5 microg/side and 1 microg/side) and TTX (5 ng/side and 10 ng/side) infusion into the ventral hippocampus dose-dependently decreased locomotor activity in an open-field experiment.     

脑缺血大鼠海马超微结构的形态定量研究

对大鼠双侧颈总动脉夹闭2小时,经透射电镜观察海马,用Weibel氏形态定量法分别测量了海马1区和3区的线粒体和突触的表面积密度(Svi)、表面积—体积比(Si/Vi),并与对照组进行了比较。结果表明:缺血时海马1区受损较严重,表现为线粒体体积缩小,数量减少,Svi下降;突触数量有增多的趋势,但突触的Svi与Si/Vi变化不明显。缺血组海马3区受损较轻,线粒体和突触的结构基本正常,其Svi、Si/Vi与对照组差别不显著,提示了3区对缺血有较强的耐受性。     

Coexistence of glutamate decarboxylase and somatostatin immunoreactivity in cultured hippocampal neurons of the rat

The immunoperoxidase-antiperoxidase method (PAP) was combined with immunofluorescence for simultaneous localization of glutamate decarboxylase (GAD)-and somatostatin-like immunoreactivity in rat hippocampal neurons growing in dissociated cell culture. A subpopulation of GAD-immunoreactive neurons additionally exhibited somatostatin-like immunostaining. GAD-negative somatostatin-positive cells could not be observed. It is discussed whether the cultured somatostatin-containing GAD neurons correspond to a certain subclass of basket cells as they occur in situ.     

西酞普兰对戊四氮点燃癫痫大鼠行为学及海马5-HT能递质系统影响的在体微透析研究

为研究5-羟色胺(5-HT)能神经递质在癫痫形成过程中的变化及西酞普兰(CTP)对其的影响,本研究用CTP(1mg/kg.d灌胃)预干预1周后,对戊四氮(PTZ,30mg/kg.d,腹腔注射)点燃癫痫过程中的行为学及在不同时间点对大鼠海马进行微透析取样,经高效液相电化学检测技术在活体观察了30只自由活动大鼠5-HT及其代谢产物5-羟吲哚乙酸(5-HIAA)水平和5-HT转化率(5-HIAA/5-HT)的动态变化。结果显示:PTZ注射后在CTP组发作潜伏期延长,发作程度轻和点燃时间延长,发作死亡率降低。点燃早期,CTP组大鼠的海马5-HT水平升高,5-HT转化率降低,与对照组和PTZ组比较,有显著性差异(P<0.05);点燃晚期CTP组和PTZ组与对照组比较5-HT水平和5-HT转化率均显著降低(P<0.05)。本研究结果提示PTZ点燃过程中,早期CTP升高脑内5-HT水平,可能直接抑制了引起爆发放电的动作电位,而抑制发作;晚期脑内5-HT神经元丢失和受体减少,功能减退,而导致CTP的作用减退。     

Adenosine receptor density and the depression of evoked neuronal activity in the rat hippocampus in vitro

The relationship between the heterogeneous distribution of A-1 adenosine receptors and the capacity of adenosine to depress neuronal activity was examined in the rat hippocampus. Utilizing autoradiographic techniques, the distribution of A-1 adenosine receptors was assessed by the binding of [3H]cyclohexyladenosine ([3H]CHA) to cryostat sections of rat brain. The apical dendritic region of CA1 showed a differential distribution of adenosine receptors between the stratum radiatum and stratum lacunosum/moleculare. The physiological relevance of this binding difference was studied in the hippocampal slice by examining the capacity of adenosine to depress evoked potentials in these two strata. It was observed that the receptor differences correlated with differential sensitivities to adenosine modulation of the evoked potentials. These data suggest that receptor density, as shown by binding techniques, may provide not only a qualitative but also a quantitative map of the sites of adenosine action.     

NR2B反义寡核苷酸对脑缺血海马CA1区NR2BmRNA表达的影响

为研究NMDA受体2B亚单位(NR2B)反义寡核苷酸(antisense oligonucleotide to NR2B,ANR2B)对短暂性脑缺血后海马CA1区NR2B mRNA表达的影响,分别向成年SD大鼠海马CA1区内立体定位注射ANR2B、NR2B正义寡核苷酸(SNR2B)、无菌生理盐水(NS),或者插针不注射(NSNO),24h后行四动脉阻断前脑缺血手术(缺血15min、再灌注24h),经心冲灌固定取脑,连续冰冻切片,原位杂交组织化学方法染色,光镜下观察各组每侧鼠脑NR2B mRNA的表达变化,并用LEICAQWin进行图像分析。结果显示,单纯缺血组海马各区的NR2B mRNA显色强度明显增加;缺血再灌组、假手术组和正常组海马CA1区内ANR2B注射点及其周围的NR2B mRNA显色明显下降;而在注射SNR2B、NS或NSNO的各组海马切片上,NR2B mRNA显色均无明显变化。结果表明ANR2B可以特异性地在体局部防止缺血后NR2B mRNA的高水平表达。     

慢性应激对大鼠空间学习记忆和海马一氧化氮的影响

目的 :探讨慢性应激对大鼠空间学习记忆和海马NO的影响。方法 :采用电击足底结合噪声建立慢性应激大鼠模型 ,Morris水迷宫观察动物的学习和记忆能力 ,同时检测海马NO含量和NOS活性。结果 :慢性应激大鼠在Morris水迷宫的空间学习和记忆能力明显下降 ,海马NO含量和NOS活性 (3 87± 0 47nmol/mgpro和 10 2 64± 13 33pmol/mgpro/min)显著高于对照组大鼠 (2 76± 0 43nmol/mgpro和 78 2 5± 10 67pmol/mgpro/min)。结论 :慢性应激损害大鼠空间学习和记忆能力 ,可能与其海马内NO增多有关