ZNC(C)PR及其类似物对大鼠脑内CNDF mRNA表达的影响

利用反转录ＰＣＲ的方法,以甘油醛３磷酸脱氢酶（ＧＡＰＤＨ）ｍＲＮＡ作为内源参照物,测定了记忆增强肽ＺＮＣ（Ｃ）ＰＲ及其类似物对大鼠海马和皮层中胆碱能神经分化因子（ＣＮＤＦ）ｍＲＮＡ表达的影响。ＺＮＣ（Ｃ）ＰＲ能显著地增强ＣＮＤＦｍＲＮＡ的表达,并在给药后１８ｈ达到高峰（海马３．０２倍,皮层５．３３倍,与对照组比较Ｐ＜０．０１）。ＺＮＣ（Ｃ）ＰＲ受体的激动剂ＮＬＰＲ也能诱导ＣＮＤＦｍＲＮＡ的表达,并比ＺＮＣ（Ｃ）ＰＲ活性更高。ＺＮＣ（Ｃ）ＰＲ受体的拮抗剂ＺＤＣ（Ｃ）ＰＲ能部分地阻断ＺＮＣ（Ｃ）ＰＲ的作用。精氨酸加压素（ＡＶＰ）只有微弱的活性,而催产素（ＯＸＴ）则没有活性。以上结果表明ＣＮＤＦ是ＺＮＣ（Ｃ）ＰＲ作用的靶基因之一,且这种作用是通过受体介导的。     

精氨酸加压素C端片段（4—8）对C6神经胶质瘤细胞胞内 …

ＺＮＣ（Ｃ）ＰＲ是精氨酸加压素（ＡＶＰ）在脑内的天然酶解产物,具有促进学习记忆的中枢效应。为了进一步阐明其作用的分子机制,以Ｃ６神经胶质瘤细胞为模型,用荧光染料Ｆｌｕｏ３负载细胞,用激光共聚焦显微镜观察胞内自由钙离子的变化情况。民现ＺＮＣ（Ｃ）ＰＲ能促进胞内钙离子的升高,这种作用是剂量依赖的,并能被其拮抗剂ＺＤＣ（Ｃ）ＰＲ所抑制,胞外钙离子对该升高没有影响。     

慢性应激对大鼠学习记忆能力和海马LTP的影响

目的和方法：本研究采用一种多因素的２１ｄ慢性应激动物模型,以Ｙ迷宫和ＬＴＰ为指标,探讨慢性应激对运动学习记忆能力和海马神经突触可塑性的影响。结果：长期慢性应激使大鼠空间学习记忆能力下降,而且,使中枢海马齿状回ＬＴＰ的诱生受到抑制。结论：慢性应激可能使大鼠海马齿状回神经突触可塑性降低,并进一步影响到学习记忆的功能。     

海马内移植颈上神经节组织改善穹窿—海马伞横切大鼠的记忆功能

３８只Ｗｉｓｔａｒ大鼠双穹窿－海马伞损伤后,以被动回避反应为指标观察到记忆明显受损,与损伤前相比,有记忆动物自６５．３％降至１３．６％,两者差别非常显著。于穹窿－海马伞损伤后记忆丧失动物（ｎ＝１５）自体一侧分离出颈上神经节（ＳＣＧ）,切为２－３块并在室温下孵育于２０－５０μｇ／ｍｌ２．５ｓＮＧＦ中１－２ｈ,而后移植于自体双侧海马背侧,移植４周后观察至动物记忆明显恢复,恢复记忆的动物数占７３．３％。     

海马内移植颈上神经节组织改善穹窿－海马伞横切大鼠的记忆功能

３８只Ｗｉｓｔａｒ大鼠双侧穹窿－海马伞损伤后．以被动回避反应为指标观察到记忆明显受损,与损伤前相比,有记忆动物自６５．３％降至１３．６％,两者差别非常显著。于穹窿－海马伞损伤后记忆丧失动物（ｎ＝１５）自体一侧分离出颈上神经节（ＳＣＧ）,切为２－３块并在室温下孵育于２０—５０μｇ／ｍｌ２．５ｓＮＧＦ中１—２ｈ,而后移植于自体双侧海马背侧,移植４周后观察到动物记忆明显恢复,恢复记忆的动物数占７３．３％。在行为实验基础上应用荧光组化方法检查了移植细胞成活情况并测量了海马内去甲肾上腺素（ＮＡ）的含量。移植后２周海马内ＮＡ含量比损伤组有明显上升。移植后一个月,可见部分移植细胞成活并有神经纤维生长。实验表明．穹窿－海马伞损伤大鼠海马内自体移植ＳＣＧ,通过神经递质的局部补充对动物丧失的记忆能力具有一定改善作用。     

AVP（4—8）增强CK—N—XH细胞内PKC和MAPK的活性

ＡＶＰ（４￣８）是精氨酸加压素（ＡＶＰ）在脑内的天然酶解产物,具有增强学习记忆的功能。为了进一步阐明其作用的分子机制,以ＳＫ－Ｎ－ＳＨ成神经瘤细胞（ＳＫ细胞）为模型进行研究。放射性配基结合实验表明,在ＳＫ细胞上存在ＡＶＰ（４￣８）的特异性结合位点。ＡＶＰ（４￣８）可以刺激ＳＫ细胞中蛋白激酶Ｃ（ＰＫＣ）和促细胞分裂原活化的蛋白激酶（ＭＡＰＫ）尖性的升高,并可以被ＡＶＰ（４￣８）的受体拮抗剂ＺＤＣ（Ｃ     

大鼠海马CA3区的习得性长时程突触增强

本实验应用慢性埋植电极技术以电生理学结合行为学的方法,观察大鼠条件性饮水反应的建立、消退和再建立过程中,其海马CA_3区突触效应的变化规律。以刺激内嗅区的穿通纤维(PP)诱发的单突触的群体锋电位(PS)及群体兴奋性突触后电位(EPSPs)为指标,经叠加处理分析,发现随着条件反应的建立,海马CA_3锥体细胞出现突触效应的长时程增强(LTP),它随行为反应的实验性消退而消退,而在随后再次建立条件反应时,又重新出现;且无论此LTP达最高水平还是它的完全消退均超前于条件性行为反应的水平。又在一个实验日训练作业结束时PS并未立即随之增大,在24h内它随时间而发展,但到第4小时已达最高水平,且条件反应率是与PS的水平相应的,对PS与EPSPs的斜率进行相关分析表明,PS的变化主要是突触传递功效的变化。上述结果表明,海马CA_3区随着行为训练有习得性LTP产生。从其发神变化特点及其与条件性行为的关系,提示此习得性LTP极其可能是本实验中学习和记忆的展经基础。     

蛋白激酶Cγ和蛋白磷酸酯酶Aα在慢性复合应激性学习记忆增强大鼠海马中表达的变化

目的 探讨蛋白激酶Cγ(PKCγ)和蛋白磷酸酯酶Aα(PP2B-Aα)在慢性复合应激性学习记忆增强大鼠海马中的表达及其意义。方法 将成年雄性Wistar大鼠随机分为应激组和对照组,对应激组实行慢性复合应激42d后,用Morris水迷宫,Y-迷宫对2组大鼠进行学习和记忆能力测试,然后用免疫组织化学方法,观察2组大鼠PKCγ和PP2B-Aα的表达,并用计算机图像分析系统对免疫阳性反应结果进行处理。结果 应激组比对照组学习记忆能力明显增强;在海马CA3区PKCγ的免疫反应阳性日月显增强;PP2B-Aα在海马CA1和CA3区的免疫反应阳性明显减弱。结论 海马内PKCγ和PP2B-Aα表达的变化可能参与了慢性复合应激致大鼠学习记忆增强的机制。     

海马长时程增强与26S蛋白酶复合体活性变化的关系

实验观察了大鼠海马脑片上突触传递长时程增强(long term potentiation,LTP)的产生和维持中26S蛋白酶复合体活性的动态变化过程,初步分析了介导其变化的受体途径。结果显示:强直刺激前,26S蛋白酶复合体活性为190±14.3 cpm/(100 μg·2 h),强直刺激诱导fEPSP斜率增加10 min时,其活性升为273±18.3 epm/(100μg·2 h),强直刺激诱导fEPSP斜率增加60 min时,26S蛋白酶复合体活性又降为210±12.8 cpm/(100μg·2 h)。NMDA受体特异阻断剂AP-5在损害L1P产生的同时,抑制26S蛋白酶复合体活性升高。实验结果提示:大鼠海马LTP产生过程中,26S蛋白酶复合体活性存在一个短时间的,依赖于N-methyl-D-aspartate(NMDA)受体的升高过程。     

幼年和老年大鼠学习中海马CA_3区长时程突触增强的年龄特征

研究发现幼年和老年大鼠在条件性饮水反应的建立、消退和再建立过程中,海马CA_3区有习得性长时程突触增强(LTP)的形成、消退和再形成现象。在它的形成和再形成以及每实验日训练作业后习得性LTP的发展上,幼年鼠明显快于老年鼠,而习得性LTP的消退,在两组间无明显差异。这既表明海马CA_3区的习得性LTP具年龄特征,也为论证习得性LTP可能是学习和记忆的神经基础之一提供了新的证据。     

ZNC(C)PR的构象及分子动力学模拟

本文用分子动力学方法和质子间距约束结合建立了ZNC(C)PR的构象。质子间距是由二维核磁共振的NOE效应得到的。结果表明ZNC(C)PR分子的主链是伸展的,但Asn2的侧链与Arg5的侧链相互靠近,使整个分子成紧密结构。在所建模型的基础上,对ZNC(C)PR进行了分子动力学摸拟。发现第一位的焦谷氨酸环很灵活,这可能意味着焦谷氨酸环对ZNC(C)PR的活性并不重要,这与实验结果是一致的。     

ZNC(C)PR affects developmental changes of P46 phosphorylation in rat hippocampus

Protein phosphorylation has been suggested to be correlated with brain development and with the molecular mechanism of behavioral effects of neuropeptides. The present study reports in vitro endogenous phosphorylation of P46, a membrane-associated protein that is changed during development of the rat hippocampus. This study indicated that the degree of endogenous phosphorylation may be correlated with the establishment of synaptic connections. Interestingly, P46 was proved to be identical to a well-known growth-associated protein B-50/GAP-43 in its identical apparent molecular weight, isoelectric point, phosphorylation dependence, and the cross immunoreaction of monoclonal anti-B-50/GAP-43 antibody and P46. Moreover, neonatal administration of neuropeptide ZNC(G)PR could facilitate the developmental progress of P46 endogenous phosphorylation. It is suggested that the changes in P46 phosphorylation could be involved in the cellular mechanism of ZNC(C)PR behavioral effects on learning. © 1993 Wiley-Liss, Inc.     

精氨加压素片段(4-8)对鼠脑PKC和PKA活性的影响

精氨加压素的 C端片段 ,AVP( 4 - 8) ,具有增强记忆的功能 ,它在大鼠脑内引发一系列的生理生化反应 .PKC经常是 G蛋白偶联受体信号传导途径中的介导激酶 ,在 AVP( 4 - 8)信号转导支路中亦不例外 .放射性配基结合实验表明 ,在海马及皮层突触膜上存在 AVP( 4 - 8)的特异性结合位点 .AVP( 4 - 8)可以刺激大鼠脑内 PKC酶活的升高 ,并可以被 AVP( 4 - 8)的受体拮抗剂 ZDC( C) PR阻断 .在同样条件下 ,AVP( 4 - 8)对 PKA酶活无显著性影响 .     

大鼠下丘脑交叉上核中CREB的昼夜节律

利用凝胶迁移率变化的实验方法,对饲养在光照－黑暗循环的条件和持续黑暗的条件下Wistar雄性大鼠下丘脑交叉上核中CREB含量的昼夜间变化进行了分析,发现CREB在交叉上核中具有内源性的昼夜节律.     

Hyperhomocysteinemia Induces Rat Memory Impairment Via Injuring Hippocampal CA3 Neurons and Downregulating cAMP Response Element-Binding Protein (CREB) Phosphorylation

Accumulated evidence demonstrated that an elevated plasma homocysteine level, hyperhomocysteinemia, induced cognitive impairment in animals, elderly and the patients with neurodegenerative diseases. To date, the underlying cellular and molecular mechanisms by which hyperhomocysteinemia induces cognitive impairment has not been clearly defined. The purpose of this study was to investigate the possible cellular and molecular mechanisms behind hyperhomocysteinemia signaling in rat memory impairment. The results from this study demonstrated that hyperhomocysteinemia induced neuronal damage and loss in hippocampal CA3 region and downregulated the cAMP response element-binding protein (CREB) phosphorylation. The findings of this study provide evidence that hyperhomocysteinemia induces rat memory impairment via injuring hippocampal CA3 neurons and downregulating CREB phosphorylation.

     

Prenatal Ethanol Exposure Decreases GAP-43 Phosphorylation and Protein Kinase C Activity in the Hippocampus of Adult Rat Offspring

Abstract: Consumption of moderate quantities of ethanol during pregnancy produces deficits in long-term potentiation in the hippocampal formation of adult offspring. Protein kinase C (PKC)-mediated phosphorylation of the presynaptic protein GAP-43 is critical for the induction of long-term potentiation. We tested the hypothesis that this system is affected in fetal alcohol-exposed (FAE) rats by measuring GAP-43 phosphorylation and PKC activity in the hippocampus of adult offspring of rat dams that had consumed one of three diets throughout gestation: (a) a 5% ethanol liquid diet, which produced a maternal blood ethanol concentration of 83 mg/dl (FAE); (b) an isocalorically equivalent 0% ethanol diet (pair-fed); or (c) lab chow ad libitum. Western blot analysis using specific antibodies to PKC-phosphorylated GAP-43 revealed that FAE rats had an ∼50% reduction in the proportion of phosphorylated GAP-43. Similarly, we found that PKC-mediated incorporation of ³²P into GAP-43 was reduced by 85% in hippocampal slices from FAE rats compared with both control groups. FAE animals also showed a 50% reduction in total hippocampal PKC activity, whereas the levels of six major PKC isozymes did not change in any of the diet groups. These results suggest that GAP-43 phosphorylation deficits in rats prenatally exposed to moderate levels of ethanol are not due to alterations in the expression of either the enzyme or substrate protein, but rather to a defect in kinase activation.     

PAF-Stimulated Protein Tyrosine Phosphorylation in Hippocampus: Involvement of NO Synthase

The effect of platelet-activating factor (PAF) on protein tyrosine phosphorylation was studied in rat hippocampal slices. PAF caused an increase in the tyrosine phosphorylation of two phosphoproteins, which we identified by immunoprecipitation assays as the focal adhesion kinase p125^FAK and crk-associated substrate p130^Cas. The PAF effect was time- and dose-dependent. In addition, the involvement of PAF receptor was demonstrated by using PCA-4248, a specific receptor antagonist. When NO synthase was inhibited by N^G-monomethyl-L-arginine (L-NMA), PAF-stimulated protein tyrosine phosphorylation was inhibited. In conclusion, our results indicate that PAF increased the tyrosine phosphorylation of both p125^FAK and p130^Cas proteins by the production of NO in hippocampus, suggesting that PAF may play a role in the functioning of this cerebral area.