Cdk13表达对神经元轴突伸长的影响

目的探讨智力障碍相关基因Cdk13对神经轴突伸长的影响。方法通过基因敲除模型、质粒细胞转染等方法,荧光共聚焦显微镜成像技术检测神经元轴突的形态,观察轴突伸长的变化。结果 Cdk12和Cdk13在神经系统中有表达,在敲除Cdk12和Cdk13后轴突长度比对照组减少,两者比较有统计学差异(P0.05),敲除Cdk12和Cdk13基因后Cdk5 mRNA水平降低。结论 Cdk13和Cdk12的表达对神经元轴突的生长至关重要,其失活会引起神经元轴突形态异常,可能是导致智力障碍的病理机制。     

Reviving through human hippocampal newborn neurons

Recent contradictory data has renewed discussion regarding the existence of adult hippocampal neurogenesis (AHN) in humans, i.e., the continued production of new neurons in the brain after birth. The present review revisits the debate of AHN in humans from a historical point of view in the face of contradictory evidence, analyzing the methods employed to investigate this phenomenon. Thus, to date, of the 57 studies performed in humans that we reviewed, 84% (48) concluded in favor of the presence of newborn neurons in the human adult hippocampus. Besides quality of the tissue (such as postmortem intervals below 26 hours as well as tissue conservation and fixation), considerations for assessing and quantify AHN in the human brain require the use of stereology and toxicological analyses of clinical data of the patient.     

褪黑素和6-羟褪黑素保护神经细胞抗缺血再灌注损伤比较研究

目的研究褪黑素(Mel)和6-羟褪黑素(6-OHMel)神经保护作用及作用机理。方法体外培养N2a细胞,模拟缺血再灌注(OGSD),加入Mel和6-OHMel,检测以下指标:①细胞生存能力:MTT法、乳酸脱氢酶释放;②细胞凋亡分析:DNA片断化,细胞色素C,Caspase3活性;③活性氧(ROS)和线粒体跨膜电位。结果①Mel和6-OHMel都能减轻OGSD诱导的N2a细胞损伤,Mel的作用强于6-OHMel。②Mel和6-OHMel均能抑制细胞色素C释放,但6-OHMel强于Mel。③Mel和6-OHMel都能稳定线粒体跨膜电位,但Mel作用时间比6-OHMel长。④Mel和6-OHMel能清除ROS,6-OHMel表现为直接作用,Mel表现为间接作用。⑤Mel和6-OHMel均能抑制caspase3的活性,但是作用时间不同。6-OHMel表现在OGSD后12h,Mel在OGSD后24h。结论Mel和6-OHMel的神经保护作用与其抗氧化、稳定线粒体功能相关,Mel的作用机制更复杂。     

Neuron transplantation into mice hippocampus alters sensitivity to barbital narcosis

The role of several hippocampal innervations in the sensitivity to barbital-induced narcosis was studied in selected mice strains. The outbred and inbred mouse strains HS/Ibg, SABRA/HUC, C57BL, CBA/LAC, and BALB/c were tested for barbital-induced sleep (315 mg/kg). The relatively short sleeping HS/Ibg (HS) and the longest sleeping BALE/c (BALE) were chosen for further investigation. Cholinergic (ACh), serotonergic (5-HT), and noradrenergic (NE) innervations were studied in HS strain; whereas BALE, which possesses both an unusually high sensitivity to barbital and unique NE innervations in the cortex and hippocampus, was employed in a detailed study of the NE innervations. Transplantation of embryonic NE cells from the mouse embryo into the hippocampus of adult HS mice increased barbital narcosis by 65% (p < 0.05), whereas transplantation of 5-HT cells decreased barbital narcosis by 54% (p < 0.001). Transplantation of ACh cells had no significant effect on barbital-induced narcosis. BALB mice were subjected to NE cell transplantation into the hippocampus and cortex. Similarly to HS, BALB receiving NE transplants into their hippocampus slept 34% longer than control after barbital challenge (p < 0.025). Noradrenergic cell transplantation into frontal cortex had no effect on barbital sleep. The results suggest that (a) enhancement by neural grafting of the NE innervation to the hippocampus accentuates and enhancement of the 5-HT innervations attenuates the sensitivity to barbital narcosis, whereas ACh innervations have no effect on the sensitivity to barbital narcosis, and (b) the unusually high sensitivity of BALB mice to barbital may not be related to its unique NE innervations.     

成年大鼠神经元和星形胶质细胞细胞周期蛋白依赖性激酶抑制因子表达的差异研究

目的比较研究成年大鼠细胞周期蛋白依赖性激酶抑制因子在神经元和星形胶质细胞的表达差异。方法应用免疫荧光和激光扫描共聚焦显微镜观察成年大鼠生理状态下大脑皮层或海马CA1、CA3、DG区神经元和星形胶质细胞细胞周期蛋白依赖性激酶抑制因子(CDKI)p15Ink4b、p21cipl的表达。结果成年大鼠海马区和大脑皮层的神经元有p15Ink4b和p21cipl的表达,细胞核和细胞浆均有表达,且以胞核为主;星形胶质细胞也有上述细胞周期调控蛋白的表达,便细胞数目较少,并且表达这些指标的星形胶质细胞多聚集在海马区。结论成年大鼠大脑皮层和海马区的神经元和星形胶质细胞均表达p15Ink4b和p21cipl,而其在神经元的表达较星形胶质细胞更为普遍。     

海洛因成瘾大白鼠中脑腹侧被盖区超微结构变化的研究

目的　模仿人类吸毒成瘾方式建立海洛因成瘾动物模型 ,研究其中脑腹侧被盖区超微结构改变 ,为深入研究海洛因成瘾神经生物学、行为学、神经药理学、成瘾戒断治疗等奠定基础。方法　采用递增法人为建立海洛因成瘾动物模型 ,设立对照组和模型组 ,取两组动物中脑腹侧被盖区于电镜下观察超微结构改变。结果　海洛因成瘾大白鼠中脑腹侧被盖区神经元胞体、轴突、树突都出现变性、坏死、调亡等超微病理结构改变。正常对照组电镜超微影像正常。结论　海洛因成瘾大鼠脑组织出现广泛性、多发性损害 ,且以变性为主 ,神经元凋亡是海洛因成瘾致脑神经元死亡的主要形式。     

小鼠持续性脑缺血后NMDA受体亚单位表达的变化

目的：研究小鼠持续性脑缺血后不同脑区NMDA受体亚单位表达的变化及其与病理损伤之间的联系。方法：采用大脑中动脉阻断法制作小鼠持续性脑缺血模型，取缺血后不同时间的皮层、海马、皮层下脑组织，用免疫印迹技术测定NMDA受体亚单位ζ1和ε1及ε2蛋白的含量。同时作冰冻切片和苏木素伊红染色，计算相应脑区神经元密度。结果：NMDA受体ζ1和ε1及ε2亚单位表达的改变发生于缺血后5h内，皮层下3个亚单位表达均明显增加，海马则各亚单位表达变化不一。脑梗塞灶和相关脑区神经元密度显著减小均出现于缺血后5h，相关脑区神经元死亡严重程度依次为皮层下组织和海马CA1区及大脑颞叶皮层Ⅲ－Ⅳ层。结论：小鼠持续性脑缺血，缺血侧脑组织NMDA受体亚单位ζ1和ε1及ε2表达的变化发生在明显的病理损害之前，表达变化程度因脑区不同，与相关脑区神经元损害的程度相应。     

Localization and characterization of epidermal growth-factor receptors in the developing rat medial septal area in culture

The presence and binding properties of epidermal growth-factor receptors (EGF-Rs) in different cell types purified from the rat medial septal area in culture were investigated. We report that astrocytes, oligodendrocytes and neurons from this area possess EGF-Rs while microglia do not. EGF-binding sites are detectable on astrocytes derived from the medial septum of both embryonic and neonatal rats. Scatchard analysis of the data for astrocytes from the fetal rats show that EGF specifically binds to both high- (K_d = 7.21 × 10⁻¹⁰ M, B_max = 3602 receptors/cell) and low-affinity (K_d = 3.99 × 10⁻⁸ 10⁻⁸ M, B_max = 6,265 receptors/cell) receptors on these cells. On the other hand, astrocytes purified from neonatal tissue possess a greater number of high-affinity receptors (B_max = 10,938 receptors/cell) when compared with the embryonic astroglia. With time in culture, the number of both types of receptors on neonatal astrocytes decreases. Oligodendrocytes also possess high- and low-affinity EGF-Rs with dissociation constants of 3.25 × 10⁻¹⁰ M and 3.85 × 10⁻⁸ M, respectively. The number of receptors on oligodendrocytes is significantly lower than those on neonatal astrocytes (B_max = 1185 and 25,081 receptors/cell for high- and low-affinity binding sites, respectively). Finally, neurons from this area also exhibit two different EGF-R types with dissociation constants similar to those described for astrocytes. As the number of receptors/neuron (B_max = 136 and 1159 receptors/cell for high- and low-affinity binding sites, respectively) appears to be extremely low, it is possible that EGF specifically binds only to a subpopulation of neurons from this area. These studies demonstrate which cell types in the developing medial sepal area posses EGF-Rs and provide a detailed characterization of these binding sites. These EGF-R-bearing cells may be potential targets for this growth factor or for transforming growth factor α in this brain area.     

高压氧对大鼠局灶性脑缺血再灌注时神经元特异性烯醇化酶的影响

目的研究高压氧(HBO)对大鼠局灶性脑缺血再灌注(IR)时．大鼠脑梗塞体积．脑组织病理改变及神经元特异性烯醇化酶(NSE)含量的影响。方法用线栓法制备阻断大脑中动脉(MCA)的局灶性脑IR模型。Wistar大鼠30只，随机分为5组：正常对照组(N组n=-6)，缺血再灌注2h 常压空气组(Rt组,n=-6)，缺血再灌注24h 常压空气组(R2组，n=-6)，缺血再灌注2h HBO组(H1组，n=-6)，缺血再灌注24h HBO组(H2组，n=-6)。R1、R2、H1、H2组缺血时间均为2h。R1、R2组暴露于常压空气，H1、H2组暴露于2．5MPa氧气。病理切片用HE染色，用Swanson方法测定脑梗塞体积，用酶联免疫法测定NSE含量。结果H1、H2组与R1、R2组相比，神经元缺血性损害较轻，脑梗塞体积缩小，NSE含量明显下降，差异有统计学意义。结论HBO能减轻缺血性脑损害，保护脑组织。     

丙烯酰胺对大鼠胚胎神经细胞分化的影响

用细胞微团培养法研究丙烯酰胺对大鼠胚胎神经细胞分化的影响。结果表明，当细胞培养物中丙烯酰胺浓度大于６０μｇ／ｍｌ时，可明显抑制细胞分化，表现为细胞集落数目减少，细胞表面突起和集落间神经纤维束减少，细胞形态改变。其半数分化抑制浓度（ＩＣｄ５０）为７５μｇ／ｍｌ，半数存活抑制浓度（ＩＣｖ５０）为９０μｇ／ｍｌ，两者较为接近。认为丙烯酰胺对细胞分化的抑制作用可能被其细胞毒作用所掩盖，其致畸作用不可忽视。