Dietary Sucrose Lowers Nociceptive Latencies Independently of Thermogenic Effects

Previous reports indicate that chronic sucrose feeding produces a significant reduction in the latency of response in the radiant heat tail-flick test. Other earlier studies have shown a relationship between tail-skin temperature and tail-flick latency, while others yet have shown an increase in tail-skin temperature following sucrose feeding. Together these previous findings suggest the possibility that dietary-induced alterations in nociceptive latencies occur as an artifact secondary to diet-related changes in tail-skin temperature. The data presented in this study show that chronic sucrose feeding significantly increased tail-skin temperature (p < 0.0001) and decreased tail-flick latency (p < 0.0001) with significant correlations between tail-skin temperatures and tail-flick latencies in both the control and sucrose fed groups. However, while the slopes of the regression lines were similar for both groups, the elevations of the lines were significantly different (p = 0.0068) suggesting a dietary impact on nociceptive thresholds independent of the temperature effect. The data were also subjected to a previously reported temperature-correction procedure and comparisons in the methods of data analysis are discussed.     

星状神经节阻滞后福尔马林诱导的伤害行为反应和间脑c-fos表达

目的　研究星状神经节阻滞 (SGB)后福尔马林诱导的家兔伤害行为反应和间脑c -fos表达。方法　在家兔星状神经节附近置入导管 ,一周后 ,选择恢复健康者 2 4只随机分为三组 :假手术组 (A组 )、SGB组 (B组 )和对照组 (C组 ) ,每组 8只。B和C组在右前肢足底皮下注射 3 %福尔马林 0 5ml致痛 ,A组同样部位注射等量生理盐水。致痛前 10min ,B组经导管给 0 2 5 %布比卡因0 5ml ,A和C组给等量生理盐水。致痛 2h ,灌注固定 ,取左右侧间脑。采用加权法对伤害行为反应评分 ,免疫组化法测间脑c -fos表达。结果　SGB后福尔马林诱导的Ⅱ期伤害行为反应明显缓解 ;B组下丘脑c -fos表达明显少于C组 (P <0 0 1) ,而B组与C组丘脑c -fos表达无显著性差异 (P >0 0 5 )。结论　SGB可减轻福尔马林诱导的Ⅱ期伤害行为反应 ,降低下丘脑c -fos表达 ,这可能与其治疗炎症痛的机制有关。     

Interaction between cerebellar neurons

Cross-correlation methods were applied to examine interaction between the cerebellar cortex and the interaction between Purkinje neurons and neurons of the deep cerebellar nuclei. Patterns of interaction between different cerebellar cortical neurons are described.     

Neurotoxic mechanism of homocysteine in hippocampal neurons

Abstract

Homocysteine (Hcy) is a neurotoxic amino acid that accumulates in several neurodegenerative disorders. We examined the consequences of treatment of cultured rat hippocampal neurons with Hcy and the effects of folate, S-adenosyl methionine (SAM) and MK-801 on Hcy-induced neuron apoptosis and the related molecular mechanisms were also observed. Primary hippocampal neurons were treated with 250 μM Hcy for 4 h resulted in apoptosis time-dependently. 100 μM S-adenosyl methionine (SAM) and 10 μM folate significantly repressed, although 1 μM MK-801, an NMDA receptor inhibitor did not, Hcy-induced neuron apoptosis. SAM and folate significantly repressed Hcy-induced neuron DNA damage. Hcy induced neuron calcium overload through activation of NMDA receptors. Hcy treatment also induced a significant increase in MDA level, but did not affect the neurons' total antioxidant capacity (T-AOC). Hcy (250 μM) significantly increased the expression of p53 and Bax while decreased the expression of Bcl-2. SAM and folate inhibited the changes of apoptosis-related protein expression induced by Hcy. These findings indicate that Hcy compromises neuronal homeostasis by not only DNA damage, but also neuron exitotoxicity, oxidative injury, apoptosis, and expression changes of apoptosis-related proteins.     

大鼠嗅觉神经元凋亡的相关研究

目的研究凋亡是否参与嗅上皮正常生理更替和嗅球摘除后嗅觉神经元死亡后再生过程，探讨凋亡与神经元再生的关系。方法应用原位末端标记法观察正常成年人鼠嗅上皮和摘除嗅球后大鼠嗅上皮12、24、48h和8d中凋亡的出现和改变情况。结果正常成年大鼠嗅上皮中有末端脱氧核苷酸转移酶介导的脱氧三磷酸尿苷缺口末端标记（TUNEL）阳性细胞[（2．35±0．43）个／200μm]，摘除嗅球后TUNEL阳性细胞数增加，24h达峰值[（102．37±19．33）个／200μm]，以后迅速下降，维持于低水平。结论凋亡参与成年嗅觉神经元生理性更替以及实验性嗅觉神经元死亡和再生的过程。可能是通过直接或间接的信号传导调节神经元前体细胞的增殖和分化。     

Serotonergic neurons in the alcohol preferring rats

Previously, we have shown that the serotonin (5-HT) content and fiber density in a number of terminal brain regions have been found to be decreased in the selectively bred, alcohol preferring (P) rats than in the alcohol nonpreferring (NP) rats. In this study, we further report that, compared with NP rats, there were fewer 5-HT-immunostained (5-HT-IM) neurons in the major ascending raphe nuclei of the P rats. Among the three major groups of 5-HT neurons responsible for the majority of ascending projections to forebrain, dorsal raphe (B₇), median raphe (B₈), and B₉, there were fewer 5-HT-IM neurons in the median and dorsal raphe (not including nucleus oralis) of P rats, compared with NP rats (unpaired Student's test). No difference was observed in the B₉ group. When the animals were treated with pargyline and L-tryptophan to enhance the 5-HT in the neurons, the number of 5-HT-IM neurons increased in both lines of rats. However, the difference in the number of 5-HT neurons between the rat lines remained. The intensity of 5-HT-IM was also found to be lower in the dorsal raphe neurons of the untreated P than in the untreated NP rats. The decreased 5-HT-IM was supported by high performance liquid chromatography measurement of 5-HT content, which also indicated that 5-HT content of the dorsal raphe was lower in the P than in the NP rats. These results indicate that lower 5-HT content and fewer 5-HT-IM neurons in the raphe account for the reduced density of detectable 5-HT-IM fibers in the terminal brain regions in the P rats, and that 5-HT neuronal transmission is reduced in the alcohol preferring rats.     

锰致神经元细胞DNA损伤作用

目的 建立体外染锰细胞模型,探讨锰神经毒性作用机制。方法 成熟原代皮层与低、中、高不同浓度的锰液,(分别为0.2,0.6,1.0 mmol/L,共孵育24 h。观察各组神经细胞形态学的变化,单细胞凝胶电泳试验(SCGE)检测神经细胞的DNA损伤,以彗星细胞尾长及彗星样细胞百分率为评价损伤指标。结果 光镜下可见不同浓度锰孵育后神经细胞形态学发生改变,SCGE显示神经细胞DNA出现不同程度的损伤,彗星尾长分别为(117.3±30.8),(136.6±29.0),(218.7±22.6)μm;彗星样细胞百分率分别为40%,43%,96%,2指标均较对照组((84.1±11.8)μm,15%)显著增加(P<0.01)。尤以高浓度锰损伤组严重,显著高于中、低浓度组(P<0.01)。结论 锰不但能引起体外培养的神经细胞外在的形态学损伤,还可导致神经细胞DNA损伤。     

Genotoxicants target distinct molecular networks in neonatal neurons

BACKGROUND: Exposure of the brain to environmental agents during critical periods of neuronal development is considered a key factor underlying many neurologic disorders. OBJECTIVES: In this study we examined the influence of genotoxicants on cerebellar function during early development by measuring global gene expression changes. METHODS: We measured global gene expression in immature cerebellar neurons (i.e., granule cells) after treatment with two distinct alkylating agents, methylazoxymethanol (MAM) and nitrogen mustard (HN2). Granule cell cultures were treated for 24 hr with MAM (10-1,000 microM) or HN2 (0.1-20 microM) and examined for cell viability, DNA damage, and markers of apoptosis. RESULTS: Neuronal viability was significantly reduced (p < 0.01) at concentrations > 500 microM for MAM and > 1.0 microM for HN2; this correlated with an increase in both DNA damage and markers of apoptosis. Neuronal cultures treated with sublethal concentrations of MAM (100 microM) or HN2 (1.0 microM) were then examined for gene expression using large-scale mouse cDNA microarrays (27,648). Gene expression results revealed that a) global gene expression was predominantly up-regulated by both genotoxicants; b) the number of down-regulated genes was approximately 3-fold greater for HN2 than for MAM; and c) distinct classes of molecules were influenced by MAM (i.e, neuronal differentiation, the stress and immune response, and signal transduction) and HN2 (i.e, protein synthesis and apoptosis). CONCLUSIONS: These studies demonstrate that individual genotoxicants induce distinct gene expression signatures. Further study of these molecular networks may explain the variable response of the developing brain to different types of environmental genotoxicants.     

胞红蛋白在缺氧神经元中的表达

目的 探讨细胞红蛋白(cytoglobin,CYGB)在体外培养神经元缺氧时的表达,为研究缺氧缺血性脑病(hypoxic ischemic encephalopathy,HIE)的生理病理机制及寻求该病新的治疗方法提供实验基础。方法 运用无血清培养技术进行胎鼠皮质神经元原代培养6 d;先用神经元特异性烯醇化酶免疫组织化学方法纯度鉴定,然后随机分配为4组,将其中3组(第1组作为对照)置于0.5%~0.9%的O₂中,用CCK8试剂盒测试细胞生存率,同时用Real-timePCR和Westernblot观察CYGB在神经元正常及缺氧不同时间点(8 h,16 h,24 h)核酸及蛋白的表达情况。结果 神经元纯度鉴定纯度大于99%;缺氧后神经元生存率随着时间推移降低,但绝大部分神经元仍存活;CYGB核酸及蛋白的表达随缺氧时间增长而递增,且每组之间差异有统计学意义(P<0.05)。结论 在体外培养的神经元细胞中,缺氧可以促进CYGB的表达,提示CYGB在缺氧性神经损伤中可能发挥某种特定的生理功能。     

小璧碱改善AD模型小鼠认知障碍作用

  目的  探讨益智聪明汤对β-淀粉样蛋白（Aβ_25-35）致阿尔茨海默病模型（AD）小鼠Tau蛋白磷酸化位点的影响。  方法  60只昆明种小鼠,随机分为假手术组,模型组,益智聪明汤低、中、高剂量组及多奈哌齐组,小鼠脑海马内注射Aβ_25-35制作小鼠AD模型,小鼠按相应剂量灌胃给药,连续15 d,1次/d;末次给药后,Western blot测定小鼠脑海马 tau蛋白磷酸化位点的表达,苏木素-伊红染色检测小鼠脑海马神经元形态学变化。  结果  与假手术组比较,模型组小鼠脑海马 tau蛋白磷酸化位点 Ser 404、Thr 231、Thr 181、Ser 396蛋白表达水平[分别为（1.800 ± 0.172）、（2.321 ± 0.140）、（2.109 ± 0.145）、（2.761 ± 0.250）]均增加（P均 < 0.05）;与模型组比较,高剂量（26.0 g/kg）益智聪明汤组小鼠海马 Ser 404、Thr 231、Thr 181、Ser 396蛋白表达水平[分别为（1.006 ± 0.158）、（1.384 ± 0.122）、（1.164 ± 0.125）、（0.978 ± 0.122）]均降低（均P < 0.05）;益智聪明汤可改善小鼠海马区神经元细胞排列紊乱、水肿等现象,并减少神经元死亡。  结论  益智聪明汤可通过降低AD模型小鼠tau蛋白磷酸化水平,减少神经元的损伤。     

微波辐射对大鼠海马神经元损伤作用

目的 观察高功率微波(HPM)辐射后原代培养大鼠海马神经元中钙-钙调蛋白依赖蛋白激酶(Ca²⁺/calmodulin-dependent protein kinaseⅡ,CaMKⅡ)的变化及其意义。方法 采用30 mW/cm²HPM辐射原代培养大鼠海马神经元,于辐射后1 h,采用免疫细胞化学等方法观察海马神经元中磷酸化-CaMKⅡ(p-CaMKⅡ)的变化。结果 30 mW/cm²HMP辐射后1 h,大鼠海马神经元细胞形态有所改变,部分细胞胞体略萎缩,胞浆减少,突起变细,长度变短;免疫细胞化学结果显示,同假辐射组比较,辐射组大鼠海马神经元胞浆中棕黄色颗粒明显增多,颜色加深;免疫荧光结果显示,同假辐射组比较,辐射组大鼠海马神经元胞浆中红色荧光明显增强。p-CaMKⅡ表达明显增加。结论 HPM辐射后大鼠海马原代培养神经元中CaMKⅡ磷酸化增强,参与了海马神经元损伤及突触可塑性改变的病理生理过程。     

Neuroprotection of spinal neurons against blunt trauma and ischemia

Each year in the Unites States there are over 10,000 new cases of para- and quadriplegia, and more than 100,000 cases of limited, but permanent, neurological losses. Many of these losses result from blunt trauma and ischemia to the spinal cord which leads to neuron death. Although blunt trauma directly kills neurons due to the physical trauma, over the subsequent 48 hours an even larger population of neurons dies due to secondary causes. One of leading triggers of this neuron death is ischemia due to the disruption of the blood circulation. Selective, but unavoidable, spinal cord ischemia occurs during thoracoabdominal surgery to repair aortic aneurysms. This ischemia leads to neuron death, functional neurological loss, and paraplegia in up to 33% of the cases. Thus, both blunt trauma and induced ischemia have similar triggers of neuron death. To reduce the neurological losses resulting from ischemia mechanisms must be found to make spinal neurons more tolerant to ischemic insult and other secondary causes of neuron death. In this review we discuss mechanisms being developed, predominantly using animal models, to provide neuroprotection to prevent neurological losses following blunt trauma and during induced spinal cord ischemia. In parallel, our own experiments are looking at neuroprotective techniques using adult human neurons. We believe the optimal neuroprotective approach will involve the perfusion of the ischemic region of the spinal cord with a hypothermia solution containing a combination of pharmacological agents.     

亚硒酸钠对神经皮质细胞氧化损伤作用

目的研究不同剂量亚硒酸钠对小鼠大脑皮层神经皮质细胞的损伤作用。方法选用24h龄ICR小鼠，培养大脑神经皮质细胞，48h后加入不同浓度的亚硒酸钠（0．004，0．020，0．100，0．500μmol／L），四甲基偶氮噻唑蓝试验检测细胞活性、激光共聚焦显微镜检测线粒体膜电位，慧星试验检测细胞DNA损伤。结果高剂量亚硒酸钠（0．1和0．5umol／L）明显抑制皮质神经细胞生长、降低线粒体膜电位、并严重损伤DNA，且呈现剂量效应关系（P〈0．05）。与对照组比较，低剂量亚硒酸钠（0．004和0．020μmol／L）虽然呈现一定毒性作用，但差异无统计学意义（P〉0．05）。结论高浓度亚硒酸钠可引起细胞损伤，降低细胞活力，其机制可能与细胞线粒体结构和功能改变以及DNA结构榻伤有关．     

The effect of exogenous melamine on rat hippocampal neurons

Rat hippocampal neurons in culture medium were exposed to different concentrations of melamine. By examining the morphology of cells detected with acridine orange staining, different changes of fluorescences of Ca2? observed with Fluo3, and caspase-3 activity assayed with optical density by enzyme linked immunosorbent assay kit, we found the effect of melamine on hippocampal neurons. Pathologic changes happened in hippocampal neurons, and there seemed to be insoluble metabolites in most of the cells with 312 μg/mL melamine stimulated for 12 hours. Then, we tested the Ca2? fluorescences of the cells above. The free intracellular Ca2? concentrations were measured using the fluorescent dye Fluo3. The average fluorescence of Ca2? in hippocampal neurons stimulated by 312 μg/mL melamine (55.43 ± 3.54) was higher than the normal ones (6.94 ± 0.14). Besides, caspase-3 activity of hippocampal neurons after being challenged with melamine was higher than that of normal ones in the mass. From the above conclusions, melamine did induce damnification to hippocampal neurons, probably in the way of inducing cells to undergo apoptotic processes and disrupting the homeostasis of Ca2?. Our experimental results disproved some viewpoints that not melamine alone, but melamine and cyanuric acid in combination could cause damage in toxicological studies and provided compelling evidence that low levels of melamine exposure may also represent a health risk to nerves, in opposition to the idea that damage of melamine and cyanuric acid in combination were limited to the kidneys.     

Glycosylation is altered by ethanol in rat hippocampal cultured neurons

AIMS: Glycoproteins, such as adhesion molecules and growth factors, participate in the regulation of nervous system development. Ethanol affects the synthesis, intracellular transport, distribution, and secretion of N-glycoproteins in different cell types, including astrocytes and hepatocytes, suggesting alterations in the glycosylation process. We analysed the effect of exposure to low doses of ethanol (30 mm, 7 days) on glycosylation in cultured hippocampal neurons. METHODS: Neurons were incubated for short (5 min) and long (90 min) periods with the radioactively labelled carbohydrate precursors 2-deoxy-glucose, N-acetyl-D-mannosamine and mannose. The uptake and metabolism of these precursors, as well as the radioactivity distribution in protein gels, were analysed. The levels of the glucose transporters GLUT1 and GLUT3 were also determined. RESULTS: Ethanol exposure reduces the synthesis of proteins, DNA and RNA and decreased the uptake of mannose, but not of 2-deoxy-glucose and N-acetyl-D-mannosamine, and it increased the protein levels of both glucose transporters. Moreover, it altered the carbohydrate moiety of several proteins. Finally, alcohol treatment results in an increment of cell surface glycoconjugates containing terminal non-reduced mannose. CONCLUSIONS: Alcohol-induced alterations in glycosylation of proteins in neurons could be a key mechanism involved in the teratogenic effects of alcohol exposure on brain development.     

小鼠原代神经元细胞狂犬病病毒滴度测定

目的探索利用小鼠原代神经元细胞测定狂犬病病毒(rabies virus,RV)滴度的可行性。方法分离培养小鼠大脑皮质原代神经元细胞,接种100小鼠脑内接种半数致死量(MICLD50)的标准攻击强毒(CVS)毒株,通过免疫荧光和反转录聚合酶链反应(RT-PCR)检测其感染性,并在此基础上在原代神经元细胞上进行了该毒株的细胞半数感染量(CCID50)测定。结果成功制备了小鼠大脑皮质原代神经元细胞;原代神经细胞培养物接种CVS 96h后,用抗微管相关蛋白质(MAP2)抗体和抗RV阳性血清作为一抗并经荧光抗体染色后,在胞体和突起上均有神经元特异性和RV特异性着染;在共聚焦显微镜下,当相同的细胞部位上出现红色和绿色交迭时呈现粉色斑点,免疫荧光证实原代神经细胞可被CVS感染,同时RT-PCR得到1 770 bp左右的目的条带,说明其被CVS感染;该原代细胞上所测定的CVS病毒滴度为104.5CCID50/0.1 mL,而该病毒的原始滴度为104.5MICLD50/0.03 mL。结论小鼠脑原代神经元细胞上测定的CVS株的病毒滴度与通过脑内接种法测定的滴度相同。     

锰对大鼠纹状体神经细胞凋亡的影响

目的利用锰染毒大鼠模型，分析不同浓度锰对大鼠纹状体神经细胞凋亡的影响，探讨锰神经毒性的作用机制。方法将健康雄性SD大鼠随机分成空白对照组和高、中、低3个剂量染锰组，每组6只动物。染毒结束，开颅分离取出大鼠纹状体，分别做锰含量测定、Tunel染色和透射电子显微镜观察。结果高、中、低3个剂量染锰组纹状体锰含量分别为（2．98±0．52）、（2．75±0．37）、（2．61±0．73）ng／mg，均高于空白对照组的（．60±0．20）ng／mg，差异有统计学意义（P〈0．05）。高、中、低3个剂量染锰组纹状体细胞凋亡指数分别为（24．83±5．98），（17．00±5．33），（15．33±2．58），均高于空白对照组的（2．83±0．41），差异有统计学意义（P〈0．05）。且随着染锰剂量的加大，细胞凋亡指数增加。染锰组大鼠纹状体的透射电子显微镜显示中剂量染锰时，部分纹状体神经细胞出现核变小、固缩，染色质浓集等细胞凋亡的特征性改变。结论锰可致大鼠纹状体神经细胞出现程度不同的细胞凋亡，而凋亡的程度与锰浓度有关。     

铅硒联合作用对原代培养海马神经元影响

目的观察铅、硒对原代培养的海马神经元生长及存活的影响，研究硒对铅的神经细胞生长抑制的拮抗作用。方法建立新生Wistar大鼠海马神经元原代无血清培养技术，通过PbCl2，Na2SeO3单独及联合作用，观察神经细胞的生长和存活情况。结果10^-5mol／L铅明显抑制了原代培养的海马神经元突起生长，引起神经元存活率下降；单独硒（2×10^-6mol／L）有明显促进海马神经元突起生长的作用．尤其在神经元突起生长早期；但对海马神经元存活率的影响不明显。铅和硒共同孵育时，培养早期硒能拮抗铅对神经元突起延伸的抑制．但随着培养时间延长，这种拮抗作用消失；从神经元存活率来看，在实验剂量下，未见硒能拮抗铅对神经元存活的抑制作用。结论铅具有抑制神经元生长和存活的毒性。本实验剂量下的硒在细胞培养早期有促进神经元突起生长和拈抗铅对神经元生长和存活的抑制作用。