神经病理性痛大鼠海马CA1区锥体神经元树突及树突棘的变化

目的:观察神经病理性痛条件下大鼠海马CA1区锥体神经元树突形态和树突棘密度的变化。方法:建立大鼠腰5脊神经结扎(L5 spinal nerve ligation,SNL)神经病理性痛模型,对照组为假手术组即只暴露腰5脊神经,不结扎。利用Von Frey纤维丝检测其50%机械性缩足阈值(paw withdrawal threshold,PWT),判断SNL模型是否成功。通过高尔基(Golgi)染色的方法观察SNL模型后14 d海马CA1区锥体神经元树突形态和树突棘密度的变化。结果:SNL模型组大鼠CA1区锥体神经元树突棘密度升高,与对照组相比有统计学差异(P0.05),而锥体神经元树突分支数无明显差异。结论:神经病理性痛会导致海马CA1区锥体神经元树突棘密度升高。     

慢性低压低氧暴露对小鼠海马CA1区神经元树突棘形态及细丝蛋白A表达的影响

目的:探讨低压低氧暴露对小鼠海马CA1区神经元树突棘形态及细丝蛋白A表达的影响。方法:6～8周龄C57BL/6雄性小鼠分为常氧暴露7 d组、常氧暴露14 d组、低压低氧暴露7 d组和低压低氧暴露14 d组。低压低氧暴露组置于低压舱模拟6 000 m海拔高原进行低压低氧暴露。Golgi染色法观察小鼠海马CA1区树突的分支数,以及基树突棘和顶树突棘长度和密度的变化; Western blot方法检测小鼠海马细丝蛋白A表达水平的变化;免疫组织荧光染色法检测小鼠海马CA1区细丝蛋白A的表达及分布变化。结果:与常氧暴露组相比,低压低氧暴露后,小鼠海马CA1区树突分支数的差异无统计学显著性,但基树突棘和顶树突棘的长度显著增加(P 0. 05),密度显著降低(P 0. 01)。低压低氧暴露后,小鼠海马细丝蛋白A表达水平低于常氧暴露组(P 0. 01或P0. 05)。免疫组织荧光染色显示细丝蛋白A在小鼠海马CA1区表达,低压低氧暴露后,海马CA1区细丝蛋白A表达水平降低(P 0. 05)。结论:慢性低压低氧暴露可影响小鼠海马CA1区细丝蛋白A表达,并导致海马CA1区神经元树突棘形态发生改变。     

慢性脑缺血大鼠海马CA1区锥体细胞树突形态及树突棘密度的变化

目的: 研究慢性脑缺血大鼠海马CA1区锥体细胞树突形态及树突棘密度的变化。 方法: 对大鼠进行双侧颈总动脉永久性结扎(2VO)制备慢性脑缺血模型,分别于2周、4周、8周通过Morris水迷宫对各组大鼠进行行为学评价,筛选造模成功大鼠,进行Golgi染色,光镜下观察海马CA1区锥体细胞树突的分支、长度及树突棘密度的变化。结果: 与对照组相比,4周、8周模型组树突的分支及长度显著减少(P<0.01),各周模型组树突棘的密度均有显著减少(P<0.01);模型组内随着缺血时间延长,树突的分支及长度、树突棘密度均显著减少(P<0.05)。结论: 慢性脑缺血可导致海马CA1区锥体细胞树突及树突棘损伤性变化,从而构成进展性认知功能障碍的病理生理学基础。     

PSD-95参与大鼠孕期铅暴露对子代海马突触影响的实验研究

目的:研究大鼠孕期铅暴露后子代海马突触变化与PSD-95表达改变的相关性,探讨铅暴露损伤学习记忆功能的机制。方法:通过饮用0.02%醋酸铅水溶液建立孕期铅暴露模型,利用原子吸收分光光度仪检测血铅,透射电镜技术检测海马突触密度,蛋白印记技术检测子代大鼠海马组织中VGLUT、VGAT和PSD-95的表达。结果:对照组和铅暴露组雄性21 d大鼠体重分别为(55.73±4.23)g和(56.01±5.97)g,无显著差异(P0.05);对照组与铅暴露组雄性21 d大鼠血铅分别为(10.2±2.1)μg/L和(301.2±34.8)μg/L,血铅水平明显升高(P0.01);对照组与铅暴露组雄性21 d大鼠单位面积突触数目分别为32.79±2.03和23.46±1.97,突触密度明显减少(P0.01);铅暴露后,VGAT的表达量没有明显变化(P0.05),VGLUT和PSD-95的表达量明显减少(P0.01)。结论:PSD-95表达减少引起海马兴奋性突触数目的下降是发育期铅暴露损伤学习记忆功能的可能机制。     

早期应激减低C57小鼠认知功能相关的海马神经元树突棘密度

目的 :借助高尔基染色法探讨早期应激对海马CA1、CA3区锥体细胞区神经元树突棘密度的影响。方法 :自出生后第2～9天,持续改变新生C57小鼠的生存环境1周,建立早年生活应激动物模型。采用ELISA CORT试剂盒检测第9日龄C57小鼠血浆皮质酮含量;针对120日龄小鼠行物体识别实验、物体位置识别实验,检测小鼠的认知功能;运用Golgi染色定量分析第9、21、120日龄3个时间点海马CA1、CA3区锥体细胞神经元树突棘的密度。结果 :9日龄应激组小鼠皮质酮含量显著增高(应激组为10.617ng/ml±2.012 ng/ml,对照组为3.300ng/ml±0.122ng/ml);120日龄应激组C 57雄性小鼠对新旧物体的识别能力表现为长期记忆(24h)能力减低;早期应激所致的负性效应持续损害海马锥体细胞区神经元至成年,表现为120日龄组C 57雄性小鼠神经元树突棘密度(每20μm树突节段树突棘数量)降低。结论 :早期应激所致负性效应延缓了海马锥体细胞区神经元树突棘的成熟和稳定,导致机体认知功能发育迟缓。     

β淀粉样蛋白1-42对大鼠海马神经元树突棘的影响

目的:研究β淀粉样蛋白1-42(Aβ1-42)对于原代培养的大鼠海马神经元树突棘形态和数量的影响.方法:将原代培养的新生大鼠海马神经元随机分为对照组(control)和Aβ1.42处理组(Aβ1-42),用浓度为500 nmol/L的Aβ1-42处理细胞,应用免疫荧光染色检测树突棘上大脑发育调节蛋白(drebrin)的...     

小鼠海马CA1区锥体神经元树突棘的发育

目的 对小鼠海马CA1区锥体神经元正常发育中树突棘密度及各种形态变化进行分析测定,为深入研究突触发生及突触可塑性提供直接的形态学依据.方法 分别取出生后0、5、10、20及30d 5个年龄段的C57BL/6小鼠各10只,采用基因枪对小鼠海马CA1区锥体神经元树突棘进行亲脂性荧光染料DiI标记,通过激光共焦显微镜对其进行观察分析;同时利用透射电镜技术对树突棘的超微结构进行分析.结果 树突棘的形态、大小及其密度随小鼠发育而变化,成熟树突棘内部存在滑面内质网与棘器,可能参与了突触后膜结合蛋白及其转运体的合成.结论 树突棘的发育过程与突触连接的形成以及突触可塑性密切相关.     

脑发育不同阶段慢性铅暴露对大鼠在体海马不同时间一氧化氮含量及合酶活性的影响

目的：比较脑发育不同阶段低浓度慢性铅暴露对大鼠在体海马一氧化氮含量及合酶活性的差异。方法：分别在仔鼠出生21天、42天、63天时测定对照组、断乳后暴露组、母体暴露组和持续暴露组仔鼠血铅含量和海马NO含量和NOS活性,并与对照组进行比较。结果：各暴露组在不同时间血铅含量均高于对照组（P〈0.05）。断乳后铅暴露组和持续铅暴露组NOS活性与对照组相比均有显著性差异（P〈0.05）,出生21天时明显高于对照组,而42天和63天明显低于对照组。持续暴露组NO含量与对照组相比有明显差异,出生21天时明显高于对照组,而42天和63天明显低于对照组。结论：脑发育任一阶段的慢性铅暴露均对海马NO含量和NOS活性有影响。与发育成熟海马相比,未成熟期海马对铅的神经毒性更为敏感,突触可塑性更易受损。     

DKK1对慢性吗啡和纳洛酮处理的培养海马神经元树突棘的影响

目的:探讨DKK1作为Wnt通路的抑制剂在吗啡依赖和纳洛酮戒断导致的神经元树突棘发育异常中是否起到一定的保护作用。树突棘是生长在神经元树突上的棘状突起,树突棘的生长与神经元突触可塑性有密切关系。方法:在原代培养的海马神经元上建立慢性吗啡依赖和纳洛酮戒断等模型,运用免疫荧光技术检测神经元树突棘的变化,Western Blot技术和免疫荧光技术检测Wnt通路关键蛋白β-catenin的变化。结果:在慢性吗啡依赖组以及慢性吗啡依赖和纳洛酮戒断组,β-catenin的表达增加并且神经元树突棘发生了明显丢失,而Wnt通路阻断剂DKK1在降低神经元内β-catenin的表达的同时对神经元树突棘的丢失起一定的抑制作用。结论:DKK1通过抑制Wnt通路对吗啡依赖所导致的海马神经元树突棘的丢失有一定作用。     

解郁丸对WKY抑郁样大鼠前额叶皮层与海马树突棘的影响

目的:观察Wistar-Kyoto(WKY)抑郁模型大鼠前额叶皮层与海马组织中树突棘的变化,并探讨解郁丸在其中的作用。方法:以成年雄性WKY大鼠为实验组,选用同品系SPF级Wistar大鼠为其对照组。首先,用糖水偏好实验、旷场实验和强迫游泳实验检测大鼠行为学变化,并作为其基线;然后将实验组所有WKY大鼠随机分为模型组、解郁丸组和西酞普兰组,与对照组分别进行21 d灌胃给药,再用相同的行为学方法检测给药后行为的变化。采用Golgi染色观察前额叶皮层与海马组织中树突棘的病理特点。Western blot检测前额叶皮层与海马组织突触后致密区蛋白95(PSD-95)的表达水平。结果:给药前,WKY大鼠表现出明显的抑郁样行为,前额叶皮层与海马组织中树突棘的密度明显降低(P<0. 01),且PSD-95蛋白的表达水平明显降低(P<0. 01);经药物治疗后,WKY大鼠的抑郁样行为明显减少,前额叶皮层与海马组织中树突棘的密度升高(P<0. 01),PSD-95蛋白的表达水平也提高(P<0. 01)。结论:解郁丸能明显减少WKY大鼠抑郁样行为,且影响树突棘的结构改变及PSD-9...     

Reversible reduction in dendritic spines in CA1 of rat and ground squirrel subjected to hypothermia-normothermia in vivo: A three-dimensional electron microscope study

A study was made at electron microscope level of changes in the three-dimensional (3-D) morphology of dendritic spines and postsynaptic densities (PSDs) in CA1 of the hippocampus in ground squirrels, taken either at low temperature during hibernation (brain temperature 2-4 degrees C), or after warming and recovery to the normothermic state (34 degrees C). In addition, the morphology of PSDs and spines was measured in a non-hibernating mammal, rat, subjected to cooling at 2 degrees C at which time core rectal temperature was 15 degrees C, and then after warming to normothermic conditions. Significant differences were found in the proportion of thin and stubby spines, and shaft synapses in CA1 for rats and ground squirrels for normothermia compared with cooling or hibernation. Hypothermia induced a decrease in the proportion of thin spines, and an increase in stubby and shaft spines, but no change in the proportion of mushroom spines. The changes in redistribution of these three categories of spines in ground squirrel are more prominent than in rat. There were no significant differences in synapse density determined for ground squirrels or rats at normal compared with low temperature. Measurement of spine and PSD volume (for mushroom and thin spines) also showed no significant differences between the two functional states in either rats or ground squirrels, nor were there any differences in distances between neighboring synapses. Spinules on dendritic shafts were notable qualitatively during hibernation, but absent in normothermia. These data show that hypothermia results in morphological changes which are essentially similar in both a hibernating and a non-hibernating animal.     

Developmental exposure to lead causes inherent changes on voltage-gated sodium channels in rat hippocampal CA1 neurons

In this study, the effects of chronic lead (Pb(2+)) exposure, during day 0 of gestation (E0) to postnatal day 15 (P15), on voltage-gated sodium channel currents (I(Na)) were investigated in CA1 field of the hippocampus (CA1) neurons using the conventional whole-cell patch-clamp technique on rat hippocampal slices. We found that developmental lead exposure increased the activation threshold and the voltage at which the maximum I(Na) current was evoked, caused positive shifts of I(Na) steady-state activation curve, and enlarged I(Na) tail-currents; Pb(2+) delayed the activation of I(Na) in a voltage-dependent manner, prolonged the time course of the fast inactivation of sodium channels; Pb(2+) induced a right shift of the steady-state inactivation curve, accelerated the activity-dependent attenuation of I(Na), but made no significant effects on the time course of the recovery of I(Na) from inactivation and the fraction of inactivated channels. In addition, the co-treatment with alpha-tocopherol (VE), an effective antioxidant and free radical scavenger, completely prevented the aforementioned changes on I(Na). The alterations on I(Na) properties induced by developmental lead exposure were partly different from that in previous acute experiments under the conditions closer to physiological situation, and the process was considered related to the participating of lead in lipid peroxidation reaction, which has been reported to change the conformation and biophysical functions of membrane proteins.     

母鼠孕哺期铅暴露及补充铁、钙对子代神经系统的影响

目的观察孕哺期铅暴露及补充铁和钙对子代学习记忆能力及海马细胞中生长抑素（SS）表达的影响。方法母鼠从孕期第1天至仔鼠出生第30天哺乳期间给以下干预：对照组（A）：饮用去离子水;染铅组（B）：饮用浓度为0．1％醋酸铅去离子水;铁＋铅组（C）：饮用浓度为0．1％醋酸铅的去离子水同时每天灌胃3．0mg／kg铁;铁＋钙＋铅组（D）：饮用浓度为0．1％醋酸铅的去离子水同时每天灌胃3．0mg／kg铁和250mg／kg钙。Y-迷宫试验用于检测仔鼠的学习记忆能力,采用免疫组织化学的方法观察仔鼠海马细胞中生长抑素（SS）阳性神经元。结果B组与A组比较,仔鼠Y-迷宫试验的错误次数明显增多（P〈0．05）,海马CA1、CA3区SS阳性神经元数量减少（P〈0．05）。D组Y-迷宫试验的错误次数比B组明显减少（P〈0．05）,海马CAI区SS阳性神经元数量增多,有统计学意义（P〈0．05）。C组则未表现上述变化。结论孕哺期母体铅暴露会损害仔鼠的学习记忆能力,补充钙剂可有所改善,而补充铁则没有明显改变,并能从海马组织中SS表达的改变得到印证。     

Ghrelin promotes reorganization of dendritic spines in cultured rat hippocampal slices

Recent evidence suggests ghrelin may up-regulate the number of spine synapses. However, it is not completely understood whether an increased number of synapses are expressed on existing spines or accommodated in newly generated spines. We examined if ghrelin might have promoted the generation of new dendritic spines. Localization of polymerized actin (F-actin), highly expressed in dendritic spines, was assayed using phalloidin, a mushroom toxin that has a high affinity to F-actin. Alexa 488-conjugated phalloidin was visualized and relative changes in fluorescing puncta were quantified using a confocal microscope. Ghrelin was applied to cultured hippocampal slices for either 60 min or 23 h. Ghrelin increased the phalloidin fluorescent signals. The antagonist of the ghrelin receptor, D-Lys3-GHSR-6, blocked the ghrelin's effect of increasing the phalloidin signal, suggesting that the ghrelin's effect was mediated by the ghrelin receptor (GHSR1a). The ghrelin-mediated increase in phalloidin signals remained elevated while ghrelin was present in the culture media for 23 h. However, removal of ghrelin from culture media restored the phalloidin signal to control level. Our results suggest ghrelin may have a stimulating effect on the generation or remodeling of dendritic spines, and the spine change persists in the presence of ghrelin. The serum ghrelin level is high when the stomach is empty, and the ghrelin level remains high until metabolic demands are fulfilled. Thus, ghrelin may be involved in food-related and appetite-related learning in the hippocampus.     

长期甲醛暴露对幼年小鼠学习记忆能力的影响

目的:研究长期甲醛暴露对幼年小鼠学习记忆能力的影响及分子机制。方法:将72只幼年C57BL/6小鼠分为对照组(control)、低浓度甲醛暴露组(FA-L)、中浓度甲醛暴露组(FA-M)和高浓度甲醛暴露组(FAH)。小鼠进行为期30 d不同浓度的甲醛暴露,称量小鼠体重变化,然后通过Morris水迷宫实验检测各组小鼠学习记忆能力,利用Nissl染色观察小鼠海马神经元结构变化,利用商品化试剂盒检测海马组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,利用Western Blot检测active caspase-3和Bcl-2等分子的表达变化。结果:与对照组小鼠相比,甲醛暴露小鼠体重增长缓慢,学习记忆能力下降,海马神经元数量减少,海马组织中SOD活性下降,MDA生成增加,active caspase-3水平增加,同时Bcl-2表达下降。结论:长期甲醛暴露可导致小鼠学习记忆能力下降,其作用机制与氧化应激反应增加并导致海马细胞凋亡有关。     

珠海地区胎儿铅暴露状况及其影响因素的探讨

目的:了解珠海市人群的胎儿铅暴露水平及其影响因素。方法:在珠海市收集脐带血标本81份,用电感耦合高频等离子体发射光谱仪测定血铅浓度,并以面谈问卷的形式对相应的81名产妇进行了社会环境及家庭生活因素调查。结果:81例脐带血血铅水平呈正态分布,范围在0590μg/L。平均值为150μg/L。脐带血血铅水平超过目前认为的安全界限(100μg/L)占67.9%。研究还发现孕妇居住房屋年代、孕妇居住地、孕期食用罐头食品是胎儿铅暴露的危险因素。多元Logistic回归分析发现,食用罐头食品对脐血铅水平的贡献在考虑了其他掺杂因素的影响后仍有统计学意义。结论:目前珠海市环境铅污染状况可能对胎儿的发育产生不利影响。