高糖对缺氧神经元的影响及钙相关机制研究

研究高糖对神经元缺氧的影响 ,并探讨其钙相关机制。利用 SD大鼠大脑皮质神经元体外缺氧模型 ,通过对细胞活力的检测 ,观察浓度分别为 2 2 .7(对照组 ) ,30 ,40 ,50 ,60 (高糖组 ) mmol/ L的葡萄糖对神经元缺氧的影响 ;以 Fura- 2 / Am为荧光指示剂 ,测定细胞内游离钙离子浓度 ([Ca2 ]i。结果发现当培养基中葡萄糖浓度达到 60 mmol/ L时 ,高糖可引起缺氧神经元损伤 ;与对照组相比 ,有钙介质与无钙介质中静息[Ca2 ]i 均升高 ,P<0 .0 1 ;但对照组与高糖组在有钙介质中对氯化钾 (KCl)、谷氨酸 (Glu)刺激引起的[Ca2 ]i 升高无明显差异 ,P>0 .0 5;在无钙介质中 ,对氯化钙 (Ca Cl2 )引起的 [Ca2 ]i 增高率无明显差别 ,P>0 .0 5。本研究表明 :高糖对神经元的损伤作用可能与其促进细胞内钙离子释放 ,诱发细胞内钙超载有关     

15-HETE影响大鼠脑动脉平滑肌细胞内钙离子浓度的机制

目的 观察15-羟化二十烷四烯酸(15-HETE)对脑动脉平滑肌细胞内钙离子浓度([Ca2+]i)的影响,进一步探讨15-HETE引起[Ca2+]i变化的钙来源,从而明确15-HETE引起脑动脉平滑肌收缩的机制. 方法 酶法分离大鼠脑动脉平滑肌细胞,分为15-HETE组与对照组,15-HETE组添加15-HETE处理;对照组正常培养,不做其他处理.激光共聚焦技术测定15-HETE对[Ca2+]i的影响;进一步通过阻断外钙内流和耗竭内钙,探明15-HETE引起钙动员的来源;应用血管环技术从功能上判定细胞外钙对15-HETE引起的颈内动脉环收缩有无影响. 结果 15-HETE组与对照组相比,[Ca2+]i明显增加,差异有统计学意义(P＜0.05);预先加入硝苯地平、镧离子及改用无钙液阻断外钙内流后,15-HETE组[Ca2+]i仍明显高于对照组,差异有统计学意义(P＜0.05);而预先加入咖啡因耗竭细胞内钙后,15-HETE组[Ca2+]i较对照组差异无统计学意义(P＞0.05);采用无钙液去除细胞外钙后,15-HETE引起的血管环张力增加与有钙液中比较差异无统计学意义(P＞0.05). 结论 15-HETE可通过促使内钙释放而使[Ca2+]i增加,进而引起大鼠脑动脉平滑肌收缩.     

丁咯地尔抑制NE和Glu引起的单个脑细胞游离钙增高

目的：研究丁咯地尔对去甲肾上腺素(NE)和谷氨酸(Glu)引起大鼠单个脑细胞内游离钙增高的影响。方法：应用AR-CM-MIC阳离子测定系统测量细胞内游离钙([Ca2+]i)。结果：细胞外钙为1．3 mmol·L,丁咯地尔0．1,1．0,1 0．0μmol·L-1对细胞静息[Ca2+]i无明显影响,对NE诱导的[Ca2+]i增高明显抑制,对Glu诱导的[Ca2+]i增高具有一定的抑制作用。结论：丁咯地尔能抑制NE和Glu引起的单个脑细胞游离钙增高。     

凝血酶对原代培养海马神经元游离钙浓度的影响

目的研究原代培养的海马神经元内游离Ca2 水平及凝血酶的影响.方法大鼠海马神经元进行体外原代培养,用钙离子指示剂Fura-2双波长法测定海马神经元内游离[Ca2 ]i及不同浓度的凝血酶作用后细胞内[Ca2 ]i.结果原代培养的海马神经元生长旺盛,密度高,符合实验要求.在胞外Ca2 浓度为0.0 mmol/L时,静息状态下海马神经元游离[Ca2 ]i为(79.83±18.78)nmol/L.当胞外Ca2 浓度为1.3 mmol/L时,海马神经元游离[Ca2 ]i为(106.41±22.53)nmo1/L.(1～40)U/ml凝血酶可使海马神经元内游离Ca2 水平显著升高,与对照组相比均有显著性差异(P＜0.01).随凝血酶浓度的增加,胞内游离[Ca2 ]i之呈剂量依赖性增加.结论凝血酶可使原代培养的海马神经元内游离Ca2 浓度明显升高.     

大鼠小直径痛觉三叉神经节神经元同时存在三磷酸肌醇敏感性钙库和阿诺碱敏感性钙库？P2X和P2Y嘌呤受体介导细胞内钙信号转导通路的变化

背景： 面部创伤或面部手术等可能损伤三叉神经系统而导致三叉神经疼痛,由于其疼痛剧烈难忍、易复发,长期以来一直为口腔临床治疗的一大难题。现有大量研究发现嘌呤类受体与三叉神经痛相关,目前对其作用机制知之甚少。 目的：探讨在小直径三叉神经节神经元中嘌呤类受体介导钙信号途径。 方法：用Fura-2荧光染料通过显微镜荧光测定技术实时检测急性分离成年大鼠小直径三叉神经节神经元的细胞内钙离子浓度。 结果：用正常外液或去除细胞外Ca2+灌流细胞,分别给予thapsigargin（1 μmol/L）,内质网钙泵ATP酶抑制剂,和咖啡因（20 mmol/L）,ryanodine受体激动剂,均能够引起细胞内游离钙离子浓度（[Ca2+]i）不同程度地升高。ATP（100 μmol/L）也能够产生类似的效应。在去除细胞外Ca2+条件下,ATP引起的[Ca2+]i升高可被thapsigargin可逆性地抑制,而不能被咖啡因抑制;然而在正常外液环境中,ATP引起的细胞内[Ca2+]i 升高不能完全地被thapsigargin抑制。 结论：在痛觉三叉神经节神经元中,嘌呤类受体介导的[Ca2+]i升高有两条途径,一种途径是通过代谢型P2Y受体作用于三磷酸肌醇敏感性钙库;另一种途径是通过离子型受体P2X受体引起外钙内流。     

慢性癫癎模型海马神经元内钙稳态和钙动力学的长期变化

目的 探讨海马神经元内长期钙离子([Ca2+]i)和动力学变化在癫疴发生机制中的作用.方法 建立氯化锂-匹罗卡品慢性癫癎模型,于致痫后6 h和1、3、7、14、30 d不同时间点应用激光共聚焦显微镜观察离体海马神经元内[Ca2+]i的变化以及谷氨酸负荷后神经元内[Ca2+]i恢复速度的变化.结果 正常对照组大鼠急性分离海马神经元[Ca2+]i为(95.4±22.1)nmol/L,致癎后急剧升高至(867.6±35.2)nmol/L,第7天降低(292.8±18.3)mnol/L,此后持续在此水平,30 d后降至(220.8±17.6)nmol/L,仍高于对照组(t=12.55,P<0.01);正常对照组大鼠92%的海马神经元内[Ca2+]i处于正常范围内(25～150 nmol/L),致癎后6 h,所有神经元[Ca2+]i均有升高,并且85%的神经元高于500 nmol/L,致癎7、14、30 d后分别有75%、60%、52%的神经元[Ca2+]i高于正常值,但高于500 nmol/L者逐渐减少;经接触5 μmol/L谷氨酸人工脑脊液2 min后,对照组神经元可在(9.5±3.4)min内恢复至基线水平,而急性期、潜伏期、慢性期的癫癎神经元均存在明显延迟(t=5.08、4.56、4.21,P<0.01).结论 氯化锂-匹罗卡品致疴后可造成海马神经元内长期的[Ca2+]i和钙动力学改变,该种长期可塑性改变在慢性癫癎模型的诱发和维持中起着重要作用.     

不同温度对谷氨酸诱发原代培养皮质神经元损伤的保护机制

目的探讨不同温度对谷氨酸诱发皮质神经元损伤的保护机制。方法体外培养新生24 h内Wistar大鼠的皮质神经元,毒性剂量的谷氨酸(200μmol·L-1)诱致皮质神经元损伤,随机分为37℃组(常温)和33℃组(亚低温),两组再根据谷氨酸持续作用时间点(10 min,3 h,6 h,24 h)分为4个亚组,标记为T1,T2,T3,T4。两组细胞均在损伤后24 h,通过激光扫描共聚焦显微镜测量细胞内Ca2+浓度([Ca2+]i)、线粒体内Ca2+浓度([Ca2+]m)及线粒体跨膜电位(ΔΨm)。结果 37℃组和33℃组的[Ca2+]i及[Ca2+]m均随损伤时间的延长而显著性增加,同时伴有ΔΨm显著下降(P0.05);33℃组较37℃组[Ca2+]i及[Ca2+]m的增加明显减少,同时显著减低ΔΨm下降幅度(P0.05)。结论 33℃可抑制谷氨酸诱发皮质神经元损伤时的[Ca2+]m内流,减少[Ca2+]m,维持ΔΨm。     

全脑缺血再灌注损伤大鼠海马细胞周期依赖性蛋白激酶-5的变化

目的 探讨急性全脑缺血-再灌注(isehemia-reperfusion,I-R)损伤时大鼠海马细胞周期依赖性蛋白激酶-5(Cdk-5)的变化.方法 用三血管结扎法建立急性全脑I-R大鼠模型.将大鼠随机分为假手术对照组、脑缺血组、I-R组及尼莫地平(nimodipine,NIM)处理组.用免疫沉淀法测定Cdk-5酶活性,用Fura-2负载及荧光测定细胞内游离Ca2+浓度{[Ca2+]I}.结果 与假手术对照组比较,脑缺血组及除I-R 5 h亚组外的其余I-R亚组大鼠海马神经元[Ca2+]I升高(P＜0.05)且伴细胞内Cdk-5活性升高(P＜0.05).NIM处理组大鼠海马细胞[Ca2+]I低于缺血组及I-R 30 min组(P＜0.05,P＜0.05),而Cdk-5的活性也低于I-R 30 min组(P＜0.05).结论 急性全脑缺血和/或再灌注时大鼠海马神经元Cdk-5活性升高,神经元[Ca2+]I升高对Cdk-5活性升高可能起重要作用.     

氯氮平及其代谢产物对大鼠胰岛细胞胞内钙的影响

目的从胞内钙离子水平探讨氯氮平及其代谢产物对离体大鼠胰岛细胞内分泌功能的影响。方法分别用低浓度(3.3mmol/L)和高浓度(16.7mmol/L)的葡萄糖Hank′s液经灌流装置孵育诱导,以终浓度为1μmol/L的氯氮平、去甲基氯氮平和N-氧化氯氮平分别作用于分离培养的大鼠胰岛细胞,并设两种浓度葡萄糖的空白对照组,以Fluo-4/AM为荧光探针,应用激光扫描共聚焦显微镜,动态监测不同药物作用于胰岛细胞后胞内钙荧光强度的变化。结果(1)低糖条件下,氯氮平组[(22±4)%]和去甲基氯氮平组[(49±6)%]胞内[Ca2+]i均低于空白对照组[(93±6)%;P<0.01];与未加处理因素前(0min)相比,氯氮平组和去甲基氯氮平组的胞内[Ca2+]i随时间的延长而降低(P<0.05~0.01),且氯氮平的抑制作用强于去甲基氯氮平(P<0.01)。(2)高糖条件下,氯氮平组[(62±10)%]和去甲基氯氮平组[(18±8)%]胞内[Ca2+]i亦均低于空白对照组[(94±5)%;P<0.01];与未加处理因素前(0min)相比,氯氮平组和去甲基氯氮平组的胞内[Ca2+]i随时间的延长而降低(P<0.05~0.01),其中去甲基氯氮平的抑制作用强于氯氮平(P<0.01)。N-氧化氯氮平组对胞内[Ca2+]i的影响不大(P>0.05)。结论氯氮平及去甲基氯氮平均降低胰岛细胞胞内[Ca2+]i,从而抑制胰岛素分泌。     

β-淀粉样蛋白对海马神经元钙离子浓度的影响及其机制研究

目的　观察β-淀粉样蛋白 (Aβ1 -40 )对海马神经元内钙离子浓度的影响及尼莫地平的拮抗作用。方法　采用大鼠海马神经元的原代培养技术 ,分别用 MTT法和激光扫描共聚焦显微镜结合 Fluo-3 /AM标记观察神经元存活率和细胞内游离钙离子浓度变化。结果　 Aβ1 -40在较高浓度 (1μmol/L和 1 0μmol/L )下 ,对神经元存活率和 [Ca2 + ]i 的影响与对照组相比 ,差异均有显著性 (P <0 .0 5 ,P <0 .0 1 ) ;5 μmol/L尼莫地平可部分降低Aβ1 -40引起的 [Ca2 + ]i 升高。结论　 Aβ1 -40可引起培养海马神经元存活率下降及胞内钙离子浓度升高 ,尼莫地平有部分拮抗作用。     

Denervation study of synapses of organ of corti of old world monkeys

Fine structural characteristics of synapses in the spiral organ of Corti were examined, with reference to differences between inner and outer haircell systems, and to location of neurons of origin of efferent axons. Surgical interruption of crossed olivocochlear bundle, of vestibular nerve, of facial nerve, and excision of superior cervical ganglia were used to determine the pathways of efferent axons. Interruption of the vestibular nerve near the brainstem results in degeneration of all efferent terminals on outer hair cells. Mid-line lesions at, and caudal to, the facial colliculus result in degeneration of about half of these efferent terminals. Efferent synaptic bulbs to the inner hair-cell system are small, of the order of one micron, and form type 2 junctions with afferent dendrites. They tend to have more large dense-core vesicles (about 80 nm) than the large efferent terminals of the outer hair-cell system, and appear to be the terminals of axons in the habenula perforata, which exhibit varicosities laden with large dense core vesicles. The varicosities are unaffected by excision of the superior cervical ganglia. So far as our material can reveal, it appears that the varicosities in the habenula perforata do not survive vestibular root interruption, nor do the efferent processes in the internal spiral bundle or at the base of inner hair cells. Most interestingly, the afferent processes of the inner hair-cell system, as identified for example by their relation to pre-synaptic bodies in the inner hair cells, are subject to a trans-synaptic reaction after severance of the vestibular root. They undergo a dramatic cytological transformation, characterized by increase of volume, engorgement with microtubules, microfilaments, microvesicles of various sizes, and clusters of lysosomes. Thus, both the efferent and afferent terminals of the inner hair-cell system show marked cytological differences from the corresponding terminals of the outer hair cell system.     

Mechanism of action of tubocurarine on nicotinic cholinoreceptors of neurons of the sympathetic ganglia of rats

Tubocurarine (Tc) effect on membrane currents elicited by acetylcholine (ACh) was studied in isolated superior cervical ganglion neurons of rat using patch-clamp method in the whole-cell recording mode. The "use-dependent" block of ACh current by Tc was revealed in the experiments with ACh applications, indicating that Tc blocked the channels opened by ACh. Mean lifetime of Tc-open channel complex, tau, was found to be 9.8 +/- 0.5 s (n = 7) at -50 mV and 20-24 degrees C. tau exponentially increased with membrane hyperpolarization (e-fold change in tau corresponded to the membrane potential shift by 61 mV). Inhibition of the ACh-induced current by Tc (3-30 microM/1) was completely abolished by membrane depolarization to the level of 80-100 mV. Inhibition of ACh-induced current was augmented at increased ACh doses. It is concluded that the open channel block produced by Tc is likely to be the only mechanism for Tc action on nicotinic acetylcholine receptors in superior cervical ganglion neurons of rat.     

The effect of age of onset of PD on risk of dementia

Background Dementia occurs in the majority of patients with Parkinson’s disease (PD). Late onset of PD has been reported to be associated with a higher risk for dementia. However, age at onset (AAO) and age at baseline assessment are often correlated. The aim of this study was to explore whether AAO of PD symptoms is a risk factor for dementia independent of the general effect of age. Methods Two community-based studies of PD in New York (n = 281) and Rogaland county, Norway (n = 227) and two population-based groups of healthy elderly from New York (n = 180) and Odense, Denmark (n = 2414) were followed prospectively for 3–4 years and assessed for dementia according to DSM-IIIR. All PD and control cases underwent neurological examination and were followed with neurological and neuropsychological assessments. We used Cox proportional hazards regression based on three different time scales to explore the effect of AAO of PD on risk of dementia, adjusting for age at baseline and other demographic and clinical variables. Findings In both PD groups and in the pooled analyses, there was a significant effect of age at baseline assessment on the time to develop dementia, but there was no effect of AAO independent of age itself. Consistent with these results, there was no increased relative effect of age on the time to develop dementia in PD cases compared with controls. Interpretation This study shows that it is the general effect of age, rather than AAO that is associated with incident dementia in subjects with PD. Received in revised form: 22 December 2005     

Limits of deinstitutionalization--perspectives of relatives of psychiatric patients

After a hopeful beginning, the social process of the reintegration of those with severe mental illness has come to a standstill. I am led to wonder whether "the community" really wants to live together with people suffering from severe mental illness, and if so, how closely? As long as the medical treatment of mental illness provided by the general practitioners is fundamentally deficient, as they are not able to prescribe the necessary interventions--such as out-patient psychiatric nursing, and service providers in the out-patient sector are content with offering increasingly intensive forms of care for the less seriously ill at the cost of the Social Welfare System--the reintegration of those with serious mental illness remains an illusion--which is mainly to the benefit of providers of residential care in homes and hostels.     

Summary of legislation of 1935 of interest to the department of Mental Hygiene

Psychiatric Quarterly -