脂多糖注入黑质对大鼠黑质纹状体单胺类递质和行为的影响

目的　探讨脂多糖 (L ipopolysaccharide,L PS)对大鼠行为学和黑质纹状体单胺类递质的影响。方法　采用立体定位注射 5μg L PS入大鼠脑黑质 ,在不同时间点观察大鼠注射阿朴吗啡后的旋转行为学 ,及采用HPL C测定黑质纹状体单胺类递质的含量变化。结果　 L PS注射后 14、2 1、3 0 d,大鼠出现向注射侧的旋转行为 ,在黑质和纹状体 ,DA及其代谢产物随时间改变呈不同程度下降 (P<0 .0 5) ,而 5-HT仅有短暂下降 ,NA无变化。结论　 L PS注入黑质特异性损害 DA能神经元 ,可降低黑质纹状体 DA及其代谢产物含量 ,诱导大鼠产生旋转行为     

左旋多巴对健康老年大鼠脑内多巴胺转运体的影响

目的　探讨长期应用左旋多巴 (L dopa)对健康老年大鼠脑内多巴胺转运体 (DAT)的影响。方法　将健康老年大鼠随机分为A、B、C 3组 ,分别每日给予口服大剂量L dopa(15 0mg/kg)、小剂量L dopa(5 0mg/kg)和生理盐水共 4个月。停药 2 4h后 ,经尾静脉注射 99mTc TRODAT 10 2ml(80 0 μGi) ,3h后处死。剥离纹状体、大脑皮质、小脑、脑干 ,称湿重 ,测定放射性计数 ,计算脑组织ID值。结果　纹状体放射活性ID值A组、B组分别为 0 .76 4± 0 .12 9和 0 .92 8± 0 .14 5 ,明显低于C组 (1.5 6 2± 0 .2 89) (P <0 0 0 1,P <0 0 5 ) ,其他部位差异无显著性。结论　长期应用L dopa可以导致纹状体部位DAT减少     

N-乙酰半胱氨酸抗谷氨酸诱导海马神经元损伤的研究

目的　观察N-乙酰半胱氨酸(N- acetylcysteine,NAC)对不同浓度谷氨酸(Glutamte,Glu)诱导海马神经元损伤的影响,探讨其作用机制,评价毒性作用。方法　采用台盼蓝活细胞拒染与TUNEL法比较不同浓度NAC预处理3d给药与细胞毒性暴露后快速给药对10 0μmol/ L、5 0 0μm ol/ L Glu诱导体外培养海马神经元损伤的影响,并与MK- 80 1比较;利用激光扫描共聚焦显微镜(L SCM)观测细胞内Ca2 浓度变化;采用台盼蓝活细胞拒染、原子力显微镜(AFM)及细胞内酯酶活性判定方法评价NAC毒性。结果　NAC可降低10 0μmol/ L Glu诱导的海马神经元死亡率,以预处理组为佳,1m mol/ L NAC预处理保护效果类似于10μmol/ L MK - 80 1;NAC对5 0 0μm ol/ L Glu诱导的海马神经元损伤无保护作用。1mm ol/ L NAC预处理抑制Glu诱导的神经元Ca2 内流。经10 0 mmol/ L NAC作用的细胞虽然形态完整,但台盼蓝染色蓝染,失去对Glu毒性的反应性;AFM扫描见神经元细胞膜皱缩;培养基Ca2 经Fluo- 3(AM)标记后L SCM下无激发荧光。结论　NAC对轻度Glu细胞毒性损伤有保护作用,预防性用药效果更优越。认为抑制Glu诱导的神经元Ca2 内流为其保护机制之一。高浓度NAC具有固定作用     

酒精对大鼠伏核诱发电位的抑制

电刺激大鼠脑片嗅结节区,记录伏核神经元的诱发电位,观察酒精对该诱发电位的影响,并用氯胺酮和L-谷氨酸进行分析.结果表明 :酒精能使伏核神经元诱发电位的幅值降低22.1%,同时酒精亦能使外源性谷氨酸引起的诱发电位幅值降低32.7%.提示酒精抑制伏核神经元的诱发电位可能与NMDA受体有关.     

慢性应激对大鼠海马CA1区长时程增强的影响及苯妥英钠的效应

目的　探讨慢性应激对海马功能的影响及苯妥英钠对它们的效应。方法　采用离体海马脑片结合电生理的方法 ,观察慢性应激对大鼠海马CA1区长时程增强 (LTP)的作用及苯妥英钠的效应。应用群体峰电位 (PS)的幅值和场兴奋性突触后电位 (fEP SP)的斜率作为观测LTP指标。在CA3区Schaffer侧支上施加高频刺激 (HFS) ,观察CA1区PS幅值和EPSP斜率在HFS前后的变化。结果　HFS后对照组和应激加苯妥英钠组LTP形成率、PS幅值和EPSP斜率变化的幅度均明显高于应激组和应激加生理盐水组 (P <0 0 5 )。对照组和应激加苯妥英钠组上述三个指标比较则无明显差异 (P >0 0 5 )。结论　慢性应激抑制海马CA1区LTP的形成 ,而苯妥英钠使应激海马LTP的形成保持在正常状态     

利鲁唑对大麻素诱导大鼠星形胶质细胞场兴奋性突触后电位长时程抑制的影响

目的:探讨利鲁唑对大麻素诱导大鼠星形胶质细胞场兴奋性突触后电位(f EPSP)长时程抑制(LTD)的影响。方法:30只2月龄SD大鼠随机分为对照组、HU210组和利鲁唑组,每组10只。对各组大鼠进行颅内双侧腹侧被盖区(VTA)立体定位并留置注射管;分别给予对照组、HU210组双侧VTA区留置管内注射生理盐水、利鲁唑组注射利鲁唑(100 pmol/μl),每侧均为10μl;30 min后分别给予对照组腹腔注射生理盐水及HU210组和利鲁唑组腹腔注射HU210 100μg/kg;均为1次/d,连续5 d。最后1次注射HU210 24 h后制备脑片,每只动物取2张脑片分别进行高频电刺激(HFS)和低频电刺激(LFS),观察f EPSP变化,即诱导长时程增强(LTP)和LTD。结果:HFS及LFS不能诱导对照组VTA脑片的LTP或LTD;HU210组脑片经LFS可以诱导出明显的LTD;利鲁唑组脑片LFS不能诱导出LTD。结论:利鲁唑能抑制大麻素诱导的大鼠神经细胞f EPSP的LTD;有望成为治疗大麻素成瘾的新途径。     

阿司匹林抑制大鼠血管平滑肌细胞增殖及p44/42 MAPK的表达

目的观察阿司匹林(ASA)对体外培养的大鼠血管平滑肌细胞增殖和磷酸化p44/42丝裂素活化蛋白激酶(MAPK)表达的影响.方法体外培养SD大鼠血管平滑肌细胞,应用不同浓度的ASA(1 mmol/L、2 mmol/L、5 mmol/L及10 mmol/L)分别作用并设立对照进行比较,采用MTS/PES法确定血管平滑肌细胞的增殖状态,利用p44/42磷酸化抗MAPK抗体的蛋白免疫印迹法测定磷酸化p44/42MAPK蛋白表达. 结果各组的细胞增殖率分别为对照组0.79±0.14;ASA1 mmol/L组0.81±0.16;ASA 2 mmol/L组0.83±0.08;ASA 5 mmol/L组0.60±0.07;ASA 10 mmol/L组0.35±0.05.统计分析显示5 mmol/L和10 mmol/L的ASA分别能明显抑制大鼠血管平滑肌细胞的增殖(P＜0.05).ASA对大鼠血管平滑肌细胞的磷酸化p44/P42 MAPK蛋白表达有显著的抑制作用(P0.05). 结论 ASA对体外培养的大鼠血管平滑肌细胞增殖和磷酸化p44/42MAPK蛋白表达均有明显的抑制作用.     

左旋多巴诱发异动症大鼠皮质纹状体突触超微结构与功能的变化

目的　探讨左旋多巴诱发异动症 (levodopainduceddyskinesias ,LID)大鼠皮质纹状体突触结构和功能的变化。方法　 6 羟多巴胺 (6 OHDA)立体定位注射制备偏侧帕金森病 (Parkinsondisease,PD)大鼠模型 ,复方左旋多巴 (L dopa)甲酯腹腔注射治疗 4周 (2 0mg·kg-1·d-1,每天 2次 )诱发LID大鼠模型。采用免疫组化及透射电镜方法对大鼠皮质纹状体突触界面的结构进行定量分析 ,并观察单次地佐环平 (MK 80 1,0 1mg/kg)治疗后突触前谷氨酸 (Glu)释放量的变化。结果　透射电镜证实皮质Glu能纤维与纹状体神经元的树突棘构成不对称突触 ,与PD大鼠比较 ,LID大鼠Glu能非对称性突触中穿孔性突触进一步增加 (P <0 0 1) ,且突触间隙变窄 ,突触后致密物质 (post synapticdensity ,PSD)厚度增加 (P <0 0 5 )。同时伴有突触前Glu释放量的增多 ,但可被N 甲基 D 门冬氨酸 (NMDA)受体拮抗剂MK 80 1所抑制。结论　慢性L dopa治疗使皮质纹状体突触功能进一步活化 ,其中涉及突触后形态和功能的改变及突触前活性的增强 ,这些突触可塑性变化与LID的发生密切相关     

酒精对大鼠伏核诱发电位的抑制

电刺激大鼠脑片嗅结节区,记录伏核神经元的诱发电位,观察酒精对该诱发电位的影响。并用氯胺酮和Ｌ－谷氨酸进行分析。结果表明：酒精能使伏核神经元诱发电位的幅值降低２２．１％,同时酒精亦能使外源性谷氨酸引起的诱发电位幅值降低３２．７％。提示酒精抑制伏核神经元的诱发电位可能与ＮＭＤＡ受体有关。     

左旋多巴治疗对实验性帕金森病大鼠黑质纹状体TNF—a表达的影响

目的　研究左旋多巴 (L - dopa)治疗对实验性帕金森病 (PD)大鼠黑质纹状体肿瘤坏死因子(TNF-α)表达的影响。方法　黑质定位注射 6 -羟多巴胺 (6 - OHDA )制备偏侧 PD大鼠模型 ,经 5 0～ 10 0 mg/ kg体重 L - dopa灌胃治疗 4周后 ,检测双侧额叶皮质、黑质和纹状体区域 TNF-α的表达。结果　 6 - OHDA损毁侧黑质和纹状体 TNF-α含量和阳性细胞面密度分别显著高于健侧 (均 P<0 .0 5 )。损毁侧与健侧 TNF-α含量的比率随 L - dopa治疗用量的增加而增高 ,且均显著高于对照组 (P<0 .0 5 )。结论　 L - dopa治疗进一步加剧了PD大鼠黑质纹状体区域 TNF-α的高表达。     

Ethanol reverses the direction of long-term synaptic plasticity in the dorsomedial striatum

The striatum is a critical structure for the control of voluntary behaviour, and striatal synaptic plasticity has been implicated in instrumental learning. As ethanol consumption can cause impairments in cognition, learning, and action selection, it is important to understand the effects of this drug on striatal function. In this study we examined the effects of ethanol on long-term synaptic plasticity in the dorsomedial striatum (DMS), a striatal subregion that plays a central role in the acquisition and selection of goal-directed actions. Ethanol was found to impair N-methyl-d-aspartic acid receptor (NMDAR)-dependent long-term potentiation (LTP) dose-dependently in the DMS, and to promote long-term depression (LTD) at the highest concentration (50 mm) used. These results suggest that ethanol, at a concentration usually associated with mild intoxication, could significantly change experience-dependent modification of corticostriatal circuits underlying the learning of goal-directed instrumental actions.     

Heterogeneity of Metabotropic Glutamate Receptors in the Striatum: Electrophysiological Evidence

In order to investigate the functional role of metabotropic glutamate receptors (mGluRs) in the striatum we performed extracellular and intracellular recordings from a corticostriatal brain slice preparation. The effects of l -2-amino-3-phosphopropionic acid ( l -AP3), an antagonist of mGluRs, were studied both on long-term synaptic depression (LTD) and on presynaptic inhibition of excitatory postsynaptic potentials (EPSPs) induced by different agonists of mGluRs. l -AP3 produced a dose-dependent (3 – 30 μM) reduction of the LTD evoked in the striatum by the tetanic stimulation of the corticostriatal pathway. In contrast to this action, l -AP3 (10 – 100 μM) did not significantly affect the presynaptic inhibitory effect of 1-amino-cyclopentyl- trans -dicarboxylic acid ( t -ACPD), an agonist of mGluRs, on corticostriatal transmission. Higher concentrations of l -AP3 (0.3 – 1 mM) reduced by themselves the EPSP amplitude. The inhibitory effect of t -ACPD on the cortically evoked EPSPs was mimicked either by the active stereoisomer 1S,3R-ACPD or by amino-4-phosphonobutyric acid ( l -AP4), a glutamate autoreceptor agonist. In some neurons, these inhibitory actions were coupled with membrane depolarizations. The depression of synaptic transmission caused by t -ACPD, 1S,3R-ACPD and l -AP4 was not altered following the induction of LTD. Chronic lithium treatment of the animals (60–120 mg/kg i.p. for 10 days) blocked striatal LTD but not presynaptic inhibition mediated by mGluR agonists. The present findings show that the mechanisms underlying LTD and the presynaptic inhibition induced by different agonists of mGluRs exhibit functional and pharmacological differences. These data suggest heterogeneity of mGluRs in the striatum.     

The effect of acute ethanol on dopamine metabolism and other neurotransmitters in the hypothalamus and the corpus striatum of mice

Summary The effect of acute ethanol on the levels of NE, DA and its metabolites DOPAC and HVA, as well as on the levels of GABA, in the corpus striatum and hypothalamus were investigated in mice in the first two hours after acute ethanol administration. There was a marked increase in the concentration of DOPAC and HVA in the corpus striatum from 30 to 120 minutes after a dose of 3.5 g/kg of ethanol even though the concentration of DA was only elevated at 60 minutes after ethanol. A dose of 1.75 g/kg of ethanol did not increase DA levels 60 minutes after administration although it did increase the concentration of DOPAC and HVA at this time. In the hypothalamus a dose of 3.5 g/kg of ethanol did not change the concentration of NE or DA but did produce a marked increase in the levels of DOPAC and HVA at 60 and 120 minutes post ethanol. A lower dose of ethanol, 1.75 g/kg, produced the same effect 60 minutes after ethanol. Ethanol caused a dose-dependent accumulation of DOPA in the corpus striatum after inhibition of DOPA-decarboxylase suggesting an increased synthesis of DA. These data suggest that the increased concentrations of DA metabolites after ethanol is secondary to enhanced DA synthesis and turnover. The concentration of NE and GABA in the hypothalamus and the corpus striatum was unchanged at any time period after ethanol.     

Suppression of the induction of long-term depression by carbon monoxide in rat cerebellar slices

Carbon monoxide (CO) suppresses brain functions at doses lower than that suppressing oxygen (O(2)) supply to the brain, and the cerebellum is one of the sites most susceptible to the neurotoxic effects of CO. We investigated the effects of CO on the induction of cerebellar long-term depression (LTD) in the synapses between parallel fibres (PFs) and Purkinje cells. CO, at concentrations between 8 nM and 5 microM, exhibited almost no effect on synaptic responses in Purkinje cells, O(2) consumption and NO release from PFs in rat cerebellar slices. However, the induction of LTD was significantly suppressed by CO at concentrations between 40 and 200 nM. The suppressive effect of 40 nM CO was antagonized by 10 microM NOR3, an NO donor. In contrast, CO exhibited no clear effect on the induction of LTD at concentrations between 1 and 5 microM. The induction of LTD, suppressed by 10 microM N(G)-nitro-L-arginine, an inhibitor of NO synthase, was not restored by 5 microM CO. CO is not only a neurotoxic substance but also a candidate for an intercellular messenger. delta-Aminolevulinate (30 microM), a substance facilitating endogenous CO production, suppressed the induction of LTD, and the effect of delta-aminolevulinate was antagonized by 10 microM NOR3. These findings suggest that CO may have a suppressive effect on the induction of cerebellar LTD at nanomolar concentrations, probably via its effects on NO/cGMP signalling.     

DJ-1 is Essential for Long-Term Depression at Hippocampal CA1 Synapses

Mutations in DJ-1 cause inherited Parkinson’s disease (PD) in several families. The normal function of DJ-1 is unknown, but mice lacking DJ-1 exhibit a deficit in dopaminergic signaling in the striatum. Since the hippocampus contains relatively high levels of DJ-1, and PD patients are often cognitively impaired, we evaluated the effects of DJ-1 deficiency on the plasticity of hippocampal CA1 synapses. LTP was slightly impaired and LTD was abolished in DJ-1−/− mice, whereas DJ-1+/− mice exhibited no alterations in synaptic plasticity. The dopamine receptor D2/3 agonist quinpirole rescued LTD in DJ-1−/− mice, suggesting a role for impaired dopaminergic signaling in the hippocampal LTD deficit.     

人外周血内皮祖细胞增殖、凋亡及丙二醛、抗氧化因子合成与波动性高糖的影响**☆

背景：研究表明波动性高血糖较持续性高血糖对血管内皮功能的损害可能更严重。 目的：观察波动性高糖对人外周血内皮祖细胞增殖、凋亡及丙二醛、抗氧化因子合成的影响。 方法：密度梯度离心法获取人外周血单个核细胞。取经培养鉴定后的内皮祖细胞，细胞同化后分别给予5.5 mmol/L，20 mmol/L，5.5/20 mmol/L葡萄糖(5.5，20 mmol/L的葡萄糖培养液每8 h更换1次)及20 mmol/L甘露醇。干预72 h后，MTT法检测内皮祖细胞的增殖情况；流式细胞仪检测细胞凋亡率；比色法测定培养液中丙二醛水平及超氧化物歧化酶活力。 结果与结论：20 mmol/L和5.5/20 mmol/L葡萄糖作用72 h，内皮祖细胞增殖减少、凋亡率增高(P < 0.01），培养液中丙二醛水平增高、超氧化物歧化酶活力降低(P < 0.01)，均以5.5/20 mmol/L葡萄糖作用最明显(P < 0.01)。说明波动性高糖较恒定性高糖更易抑制内皮祖细胞增殖并促进其凋亡，其机制可能与波动性高糖环境下氧化应激水平增高有关。     

The small‐conductance calcium‐activated potassium channel is a key modulator of firing and long‐term depression in the dorsal striatum

The striatum is considered to be critical for the control of goal‐directed action, with the lateral dorsal striatum (latDS) being implicated in modulation of habits and the nucleus accumbens thought to represent a limbic–motor interface. Although medium spiny neurons from different striatal subregions exhibit many similar properties, differential firing and synaptic plasticity could contribute to the varied behavioral roles across subregions. Here, we examined the contribution of small‐conductance calcium‐activated potassium channels (SKs) to action potential generation and synaptic plasticity in adult rat latDS and nucleus accumbens shell (NAS) projection neurons in vitro. The SK‐selective antagonist apamin exerted a prominent effect on latDS firing, significantly decreasing the interspike interval. Furthermore, prolonged latDS depolarization increased the interspike interval and reduced firing, and this enhancement was reversed by apamin. In contrast, NAS neurons exhibited greater basal firing rates and less regulation of firing by SK inhibition and prolonged depolarization. LatDS neurons also had greater SK currents than NAS neurons under voltage‐clamp. Importantly, SK inhibition with apamin facilitated long‐term depression (LTD) induction in the latDS but not the NAS, without alterations in glutamate release. In addition, SK activation in the latDS prevented LTD induction. Greater SK function in the latDS than in the NAS was not secondary to differences in sodium or inwardly rectifying potassium channel function, and apamin enhancement of firing did not reflect indirect action through cholinergic interneurons. Thus, these data demonstrate that SKs are potent modulators of action potential generation and LTD in the dorsal striatum, and could represent a fundamental cellular mechanism through which habits are regulated.     

Contribution of GABAergic inhibition to synaptic responses and LTD early in postnatal development in the rat superior colliculus

We studied the development of optic tract evoked field potentials (FP) in the rodent superior colliculus (SC) and the effect of GABA antagonists upon their development and upon induction of long-term depression (LTD). Brain slices were cut from Lister Hooded rats. The optic tract was stimulated while recording from the superficial grey layer. GABAergic inhibition was assessed by adding 100 microm picrotoxin and 3 microm CGP55845 antagonists to block GABA A,B,C receptors. LTD was induced with a 50 Hz, 20 s tetanus. At age P2, the FP consisted only of a presynaptic spike. The GABA antagonists had no effect. By P4, the FP consisted of a presynaptic spike, a longer latency population spike, and a field excitatory postsynaptic potential (fEPSP). The fEPSP was slightly prolonged by the GABA antagonists at this age. By P7-P14, a prominent FP with trailing fEPSP was recorded. The GABA antagonists usually had a large effect, with the fEPSP increasing in both amplitude and duration. A mature FP was usually recorded in P15-P23 slices where the GABA antagonist effect remained substantial. LTD could be induced in 17 of 30 control slices from rats aged P4-P26. The average fEPSP amplitude after tetanus was 77.9% of control. Pre-treatment with GABA antagonists produced a short-term potentiation (average 114.0%), rather than LTD, in 14 of 19 cases. This STP was followed by a more prolonged potentiation in 12 of the 14 cases. We conclude that GABAergic inhibitory circuits mature before eye opening and that GABA contributes to induction of LTD in the developing SC.     

Modulatory metaplasticity induced by pregnenolone sulfate in the rat hippocampus: A leftward shift in LTP/LTD‐frequency curve

We recently have found that an acute application of the neurosteroid pregnenolone sulfate (PREGS) at 50 μM to rat hippocampal slices induces a long‐lasting potentiation (LLP_PREGS) via a sustained ERK2/CREB activation at perforant‐path/granule‐cell synapses in the dentate gyrus. This study is a follow up to investigate whether the expression of LLP_PREGS influences subsequent frequency‐dependent synaptic plasticity. Conditioning electric stimuli (CS) at 0.1–200 Hz were given to the perforant‐path of rat hippocampal slices expressing LLP_PREGS to induce long‐term potentiation (LTP) and long‐term depression (LTD). The largest LTP was induced at about 20 Hz‐CS, which is normally a subthreshold frequency, and the largest LTD at 0.5 Hz‐CS, resulting in a leftward‐shift of the LTP/LTD‐frequency curve. Furthermore, the level of LTP at 100 Hz‐CS was significantly attenuated to give band‐pass filter characteristics of LTP induction with a center frequency of about 20 Hz. The LTP induced by 20 Hz‐CS (termed 20 Hz‐LTP) was found to be postsynaptic origin and dependent on L‐type voltage‐gated calcium channel (L‐VGCC) but not on N‐methyl‐D ‐aspartate receptor (NMDAr). Moreover, the induction of 20 Hz‐LTP required a sustained activation of ERK2 that had been triggered by PREGS. In conclusion, the transient elevation of PREGS is suggested to induce a modulatory metaplasticity through a sustained activation of ERK2 in an L‐VGCC dependent manner. © 2009 Wiley‐Liss, Inc.     

Ethanol-induced alterations in the expression of neurotrophic factors in the developing rat central nervous system

Neonatal rats were exposed to ethanol throughout gestation, or during the early postnatal period (postnatal days 4-10 (P4-10)), and enzyme-linked immunoabsorbent assays were subsequently conducted in order to assess nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) protein content in hippocampus, septum, cortex/striatum and cerebellum. These determinations revealed that following prenatal ethanol treatment, there were significant ethanol-induced increases in NGF in P1 cortex/striatum, but no changes in any of the three neurotrophic factors (NTFs) in the other brain regions. Cortex/striatal NGF protein returned to control levels by P10. Following early postnatal exposure, BDNF was elevated in hippocampus and cortex/striatum (assessed on P10), and NGF was also enhanced in cortex/striatum at this age. Hippocampal and cortex/striatal BDNF returned to control levels by P21, but cortex/striatal NGF levels remained enhanced at this age. This NTF did not differ in ethanol and control animals by P60, however. The possible significance of elevated levels of NTFs as a function of ethanol exposure is discussed, and it is speculated that while such alterations could play a protective role, increases in these substances during critical developmental periods could also prove to be deleterious, and could even contribute to certain of the neuropathologies which have been observed following developmental ethanol exposure.