异丙酚对神经元缺氧损伤的保护及其作用机制

目的　研究异丙酚对离体大鼠海马神经元缺氧损伤的保护作用及其机制。方法　以原代培养的大鼠海马神经元作为研究对象 ,建立缺氧、H2 O2 和谷氨酸损伤模型 ,用MTT法测定神经元存活率。采用激光扫描共聚焦显微镜动态监测缺氧前后 ,单个海马神经元内Ca2 + 浓度和线粒体膜电位 (△Ψm)的变化。用电子自旋共振技术测定异丙酚对羟基自由基和超氧阴离子自由基的清除作用。结果　 6～ 4 8mg·L-1浓度的异丙酚可明显降低神经元缺氧损伤时的细胞死亡率 (P <0 0 1) ,作用程度均呈剂量相关 (r =0 89,P <0 0 5 ) ;2 4～ 4 8mg·L-1浓度的异丙酚可明显降低H2 O2 损伤时的细胞死亡率 (P <0 0 1) ;12～ 4 8mg·L-1浓度的异丙酚可明显降低谷氨酸损伤时的细胞死亡率 (P <0 0 1)。 3～ 4 8mg·L-1异丙酚对缺氧诱发的细胞内钙离子超载有抑制作用(P <0 0 5 ) ;12、4 8mg·L-1异丙酚能减缓缺氧引起的△Ψm降低 (P <0 0 1)。 12、4 8mg·L-1异丙酚对羟基自由基的清除率分别为 17 1%和 2 1 1% ,但对超氧阴离子自由基无清除作用。结论　异丙酚对离体培养的大鼠海马神经元缺氧性损伤具有保护作用 ,其作用机制部分与异丙酚抑制缺氧引起的 [Ca2 + ]i 异常升高、抑制线粒体膜电位的下降和清除羟基自由基有关     

健脑安对血管性痴呆大鼠海马区IL-1β和CRF蛋白异常表达的影响

目的观察具有益气补肾活血化痰作用的中药提取物健脑安对血管性疾呆(VaD)大鼠海马区表达升高的白细胞介素1β(interleukin-1,IL-1β)、促肾上腺皮质激素释放因子(corticotropin-releasing factor,CRF)的影响。方法对 Koizumi 和 Nagasawa 法加以改进,采用同侧颈总动脉永久结扎线栓法制备大脑中动脉梗塞(MCAO)大鼠模型,2h 后实现大脑中动脉再灌。动物分成中药健脑安大(19.34g 生药/ml)、中(9.67g 生药/ml)、小(4.83g 生药/ml)剂量组、白细胞介素1受体拮抗剂(IL-1ra)对照组、模型组和假手术组。中药干浸膏用0.5%羧甲基纤维素(CMC)配咸水溶液,每100g 大鼠给中药溶液0.7ml;IL-1ra 对照组大鼠在缺血前30min和缺血后10min 左侧脑室内分别注射人重组 IL-1ra 10μg;3个中药剂量组、假手术组、模型组分别于造模7天前开始灌胃中药及清洁水,分别按照缺血再灌后不同时间点(2、3、4、12h 和7天)取材。应用免疫组化方法标记实验各组大鼠脑海马区组织中 IL-1β和 CRF 蛋白阳性神经元的数量。结果...     

多层CT作肺血管分期造影对肺癌侵犯中央肺动脉的评估

目的 探索多层螺旋CT作肺血管分期造影的可能性和评价肺癌侵犯中央肺动脉的临床价值。方法 用多层螺旋CT对73例肺门区肺癌患者进行研究。分两段对比剂注射，结合三个扫描程序作肺血管分期造影，根据肺动脉被侵犯的不同部位和程度分为三度。按盲法评价图像并与手术和病理对照。结果 肺动脉分期造影成功的共68例(93.15％，68/73)。肺动脉I度侵犯者4例(5．88％，4／68)，Ⅱ度侵犯者9例(13．23％，9/68)，Ⅲ度侵犯者55例(80．88％，55/68)。I度者全部作肺叶切除;Ⅱ度与Ⅲ度者的肺叶切除率有显著性差异(x^2＝64．03，P＜0.005)；Ⅲa度与Ⅲb度者的肺叶切除率也有显著性差异(x^2＝68．69，P＜0.005)，Ⅲc度全部放弃手术。结论 多层螺旋CT作肺血管分期造影能更好地显示肺癌侵犯中央肺动脉的部位和程度，为选择外科治疗方案提供更多的影像学依据。     

调心方活性部位对大鼠海马脑片CA1区诱发LTP的影响

目的：研究调心方活性部位A对大鼠海马脑片诱发长时程增强(LTP)效应的影响。方法：采用细胞外微电极记录技术，记录大鼠海马脑片CA1区诱发群峰电位(PS)，然后施以100Hz，100串的强直刺激诱发LTP。结果：调心方活性部位A对大鼠海马脑片正常PS的形状、幅度无影响，提示并不影响海马的基础突触传递。给予强直刺激后，高浓度活性部位A可以明显增大LTP幅度，提示具有促进和维持LTP的作用。结论：调心方活性部位A可能是调心方促进和维持大鼠海马脑片诱发LTP的有效成分之一，对LTP的促进作用也是调心方活性部位A益智作用的机制之一。     

Transient depression of excitatory synaptic transmission induced by adenosine uptake inhibition in rat hippocampal slices

The transient property of the dipyridamole-induced depression of excitatory synaptic transmission was analyzed using field EPSPs (fEPSPs) recorded from the CA1 region in rat hippocampal slices. The fEPSPs were depressed by 1 microM dipyridamole and then gradually recovered to the control level. The depression was antagonized by aminophylline or DPCPX, although it was not significantly affected by DMPX. The results suggest that the fEPSP depression is induced by a mechanism through the A(1) receptor.     

Dexamethasone induces TrkA and p75NTR immunoreactivity in the cerebral cortex and hippocampus

Nerve growth factor (NGF) plays a crucial role in synaptic plasticity during brain development and adulthood by activating a dual receptor system composed of TrkA and p75 (p75NTR) receptors. Exogenous NGF modulates the expression of both receptors. Little is known about the ability of endogenous NGF to regulate the expression of these receptors in basal forebrain cholinergic terminals. The ability of glucocorticoids to increase NGF expression in the hippocampus prompted us to investigate whether the synthetic glucocorticoid dexamethasone (DEX) increases TrkA and p75NTR expression in NGF-target cholinergic neurons in developing rats. We first examined the effect of DEX on NGF mRNA by in situ hybridization. DEX given systemically (0.5 mg/kg, sc) for 1 week to 7-day-old rats elicited an increase in NGF mRNA levels in the dentate gyrus of the hippocampus and superficial layers II and III of the cerebral cortex. Immunohistochemical analysis of p75NTR and TrkA levels revealed a dramatic increase in p75NTR immunoreactivity (IR) in both basal forebrain and hippocampus and TrkA IR in the hippocampus. Interestingly, in DEX-treated rats more axonal terminals were immunopositive for p75NTR in the hippocampus and cortex, suggesting an increase in p75NTR IR in cell bodies as well as in terminals. Our data indicate that the endogenously produced NGF elicits biological changes similar to those of the exogenously delivered NGF. We suggest that glucocorticoids might regulate and coordinate cholinergic neuronal maturation by increasing the biosynthesis of NGF.     

Involvement of calmodulin-dependent protein kinase II in carbachol-induced rhythmic activity in the hippocampus of the rat

The role of calcium and protein kinases in rhythmic activity induced by muscarinic receptor activation in the CA1 area in rat hippocampal slices was investigated. Extracellular recording showed that carbachol (20 microM) induced synchronized field potential activity with a dominant frequency of 7.39+/-0.68 Hz. Pretreatment with the membrane permeable Ca(2+) chelator BAPTA-AM (50 microM) or with thapsigargin (1 microM), a compound which depletes intracellular calcium stores, reduced the dominant power of carbachol-induced theta-like activity by 83% and 78%, respectively. Inhibition of calmodulin-dependent protein kinase II (CaMKII) by the cell permeable inhibitor KN-93 (10 microM) reduced the power of carbachol-induced theta-like activity by 80%. In contrast the protein kinase C (PKC) inhibitor calphostin C did not significantly (P>0.05) affect the effect of carbachol. Whole-cell recording indicated that KN-93 also blocked carbachol-induced suppression of slow I(AHP) and strongly inhibited the carbachol-induced plateau potential. Our data suggest that activation of CaMKII by carbachol is crucial for local theta-like activity in the CA1 area of the rat hippocampus in vitro. Furthermore, involvement of CaMKII in carbachol-induced suppression of the slow I(AHP) and the induction of plateau potentials could play a role in the induction of theta-like rhythmic activity by carbachol.     

保存时距对短期记忆之记忆量的影响

目的:通过对大学生短期记忆之记忆量的测定,探讨保存时距对短期记忆的记忆量的影响。方法:以学习材料(每组20个汉字,共5组)、电脑、大学生为研究对象(42名北大医学部2003级学员参加实验),实验中包括1 s立即回忆,2 s立即回忆,1 s延迟回忆,2 s延迟回忆4种不同的测验方式,并随机分配给42名参加实验的学员进行测量。结果:进行F检验作保存时距与短期记忆保留量之间的分析得到,在短期记忆中,时距的长短对记忆量的影响很大,而在长期记忆中,时距的长短对记忆量的影响不大;当保存时距较长时,延迟作用比较明显,而当保存时距较短时,延迟作用并不明显。     

丝素纤维与海马神经元的生物相容性细胞培养研究

目的:研究丝素与体外培养的大鼠海马神经元的生物相容性。方法:采用制备丝素与SD大鼠胎鼠海马神经元共培养7天,每天倒置显微镜观察,免疫细胞化学染色激光共聚焦显微镜观察、分析。结果:通过光镜观察,发现大鼠海马神经元与丝素纤维共培养3天后,海马神经元附着于丝素纤维,神经突起沿丝素纤维向远处生长、延伸;培养7天后海马神经元形成神经元网络,包绕丝素纤维。免疫细胞化学染色显示附着于丝素上的细胞为神经元。结论:海马神经元沿着丝素纤维包裹生长,提示丝素纤维与海马神经元具有良好的生物相容性。     

吗啡对海马结构Bcl—Xs表达的影响

目的 研究吗啡对小白鼠海马结构Bcl—Xs表达厦神经元凋亡的影响。方法 免疫组化ABC法和图像分析与统计。结果 对照组小白鼠的海马结构有Bcl—Xs弱阳性表迭。注射吗啡10d后，小白鼠的海马结构有Bcl—Xs强阳性表迭：注射吗啡20d后。海马结构有Bcl—Xs极强的阳性表迭，并可见神经元凋亡；注射吗啡30d后，海马结构内神经元的凋亡加速，并有大量的空泡形成，Bcl—Xs的表迭减弱。结论 吗啡能促进Bel—Xs表迭，诱导神经元凋亡。