HSV介导的神经营养因子-3体外表达拮抗顺铂的耳毒性作用

目的　观察单纯疱疹病毒 (HSV)扩增子型表达载体介导的神经营养因子 3(NT 3)体外表达对顺伯耳毒性的拮抗作用。　方法　以HSV扩增子型表达载体为基础 ,构建由CMV作启动子 ,表达c myc标记的大鼠NT3或鼠的小肠碱性磷酸酶 (MIAP)的HSVnt3和HSVmaip扩增子型表达载体。通过无辅助病毒的包装体系包装后 ,感染体外培养的耳蜗器官 ,经不同浓度的顺铂处理 4 8h后 ,观察转导NT 3或报告基因 (MIAP)后的耳蜗螺旋神经节细胞存活和神经突起的再生。　结果　显示在病毒滴度 (MOI)为 0 2 5时 ,HSVnt3感染体外培养的耳蜗 4 8h后 ,能够刺激耳蜗分泌较高水平的NT 3(3μg L)。用不同浓度的顺铂处理 4 8h ,HSVnt3转导的耳蜗螺旋神经节细胞可以在一定范围内 ,耐受顺铂的耳毒性作用 ,与HSVmiap转导的耳蜗比较 ,神经元残留的数量明显高于对照组 (P <0 0 0 1) ,耳蜗螺旋神经节细胞神经突起的长度和密度也与对照组有明显的差别 (P <0 0 0 1)。　结论　提示无辅助病毒的HSV所介导的神经营养因子 3表达 ,能够在体外拮抗顺铂的耳毒性作用。     

NRAGE影响人食管癌细胞放射抗性的作用及其机制研究

背景与目的：食管癌是全球威胁人类生命和健康的常见恶性肿瘤之一，中国每年食管癌发病人数占全球发病总人数的一半以上，以食管鳞癌最为常见。放疗是食管癌三大治疗手段之一，而放射抗性是导致其治疗失败的主要原因。神经营养因子受体相互作用MAGE类药物（neurotrophin receptor-interacting MAGE homolog，NRAGE）在放射抗性细胞株TE13R120中表达量明显高于亲本TE13细胞，且NRAGE亚细胞定位变化可能参与食管癌细胞放射抗性的形成。通过基因转染构建NRAGE稳定表达的食管癌细胞系，以进一步明确NRAGE基因与食管鳞癌细胞放射抗性的关系，分析该基因影响放射抗性的具体机制。方法：通过基因转染构建NRAGE稳定表达的食管癌细胞系。采用细胞克隆形成实验检测细胞放射敏感性，采用流式细胞术检测细胞周期及凋亡；细胞划痕、Transwell侵袭实验检测细胞迁移、侵袭能力，采用实时荧光定量聚合酶链反应（real-time fluorescence quantitive polymerase chain reaction，RTFQ-PCR）和蛋白质印迹法（Western blot）检测细胞中β-catenin表达情况。组间差异采用t检验或方差分析。结果：实验分为转染过表达组（Eca109/NRAGE组）和空白对照组（Eca109组）。Eca109/NRAGE细胞中NRAGE的表达量明显高于Eca109（t=29.65，P<0.05）。照射后Eca109/NRAGE细胞的放射抗性显著高于Eca109。流式细胞术检测结果显示，Eca109/NRAGE细胞中对射线抵抗性最强的S期细胞比例增加，对射线最敏感的G ₂ /M期减少。Eca109/NRAGE细胞凋亡率较Eca109细胞降低（t=3.268，P<0.05）。Eca109/NRAGE细胞迁移和侵袭能力均高于Eca109。RTFQ-PCR和Western blot检测结果显示，β-catenin的mRNA表达及蛋白水平在Eca109/NRAGE细胞中明显高于Eca109（t=15.87，P<0.05）。结论：NRAGE参与Eca109细胞放射抗性的形成，改变细胞的细胞周期分布和凋亡情况，影响细胞迁移及侵袭能力并可能影响食管癌细胞的放射敏感性，该作用可能与激活Wnt/β-catenin信号转导通路有关。     

The effect of P75 on Trk receptors in neuroblastomas

Neuroblastomas (NBs) with favorable outcome usually express TrkA, whereas unfavorable NBs frequently express TrkB and its cognate ligand BDNF. P75 (p75(LNTR), NGFR, TNFRSF16) binds NGF-related neurotrophins with low affinity and usually is coexpressed with Trk receptors in NBs. Here, we investigated the importance of p75 coexpression with Trk receptors in NBs. We transfected p75 into two Trk-null NB cell lines, SH-SY5Y and NLF that were also engineered to stably express TrkA or TrkB. Cell numbers were compared between single (Trk alone) and double (Trk+p75) transfectants, and proliferation was assessed by flow cytometry. P75 coexpression had little effect on cell growth in Trk NB cells in the absence of ligand, but it increased sensitivity and greatly enhanced the effect of cognate ligand. Exogenous NGF induced greater phosphorylation of TrkA and AKT. This was associated with increased cell number in TrkA/p75 cells compared to TrkA cells (p<0.01), which was due to increased proliferation in TrkA/p75 cells (p<0.05), followed by differentiation. Exogenous BDNF also increased cell number in TrkB/p75 compared to TrkB cells (p<0.01), due to an increase in proliferation, but without differentiation. Coexpression of p75 also increased specificity of Trk-expressing cells to ligand. NT3-induced phosphorylation of TrkA and AKT was reduced in TrkA/p75 cells. NT3-induced phosphorylation of TrkB (as well as AKT and MAPK) was also reduced with p75 coexpression. Our results suggest that p75 plays an important role in enhancing both the sensitivity of Trk receptors to low levels of ligand, as well as increasing the specificity of Trks to their cognate ligands. It also enhances ligand-induced differentiation in TrkA/p75 but not TrkB/p75 cells.     

Trophic and proliferative perturbations of in vivo/in vitro cephalic neural crest cells after ethanol exposure are prevented by neurotrophin 3

Neural crest cells (NCCs), a transient population that migrates from the developing neural tube, distributes through the embryo and differentiates into many derivatives, are clearly involved in the damage induced by prenatal exposure to ethanol. The aim of this work was to evaluate alterations of trophic parameters of in vivo (in ovo) and in vitro NCCs exposed to teratogenic ethanol doses, and their possible prevention by trophic factor treatment.Chick embryos of 24-30 h of incubation were treated during 10 h with 100 mM ethanol, or 40 ng/ml Neurotrophin 3 (NT3), or 10 ng/ml Ciliary Neurotrophic Factor (CNTF), or ethanol plus NT3 or CNTF, or defined medium; then the topographic distribution of NCC apoptosis was assessed using a whole-mount acridine orange supravital method. Cultures of cephalic NCCs were exposed to the same ethanol or NT3, or CNTF treatments, or ethanol plus one of both trophic factors, or N2 medium. A viability assay was performed using the calcein-ethidium test, apoptosis was evaluated with the TUNEL test, and proliferative capacity after BrdU labeling.After direct exposure of embryos to 100 mM ethanol for 10 h, a high level of NCC apoptosis was coincident with the abnormal closure of the neural tube. These anomalies were prevented in embryos exposed to ethanol plus NT3 but not with CNTF. In NCC cultures, high cell mortality and a diminution of proliferative activity were observed after 3 h of ethanol treatment. Incubation with ethanol plus NT3 (but not with CNTF) prevented NCC mortality as well as a fall in NCC proliferation.The consequences of direct exposure to ethanol expand data from our and other laboratories, supporting current opinion on the potential risk of alcohol ingestion (even at low doses and/or during a short time), in any period of pregnancy or lactation. Our in vivo/in vitro model encourages us to examine the pathogenic mechanism(s) of the ethanol-exposed embryo as well as the use of trophic factors for the treatment and/or prevention of anomalies induced by prenatal alcohol.     

Endogenous BDNF regulates induction of intrinsic neuronal growth programs in injured sensory neurons

Identification of the molecule(s) that globally induce a robust regenerative state in sensory neurons following peripheral nerve injury remains elusive. A potential candidate is brain-derived neurotrophic factor (BDNF), the sole neurotrophin upregulated in sensory neurons after peripheral nerve injury. Here we tested the hypothesis that BDNF plays a critical role in the regenerative response of mature rat sensory neurons following peripheral nerve lesion. Neutralization of endogenous BDNF was performed by infusing BDNF antibodies intrathecally via a mini-osmotic pump for 3 days at the level of the fifth lumbar dorsal root ganglion, immediately following unilateral spinal nerve injury. This resulted in decreased expression of the injury/regeneration-associated genes growth-associated protein-43 and Tα1 tubulin in the injured sensory neurons as compared to injury plus control IgG infused or injury alone animals. Similar results were observed following inhibition of BDNF expression by intrathecal delivery of small interfering RNAs (siRNA) targeting BDNF starting 3 days prior to injury. The reduced injury/regeneration-associated gene expression correlated with a significantly reduced intrinsic capacity of these neurons to extend neurites when assayed in vitro. In contrast, delayed infusion of BDNF antibody for 3 days beginning 1 week post-lesion had no discernible influence on the elevated expression of these regeneration-associated markers. These results support an important role for endogenous BDNF in induction of the cell body response in injured sensory neurons and their intrinsic ability to extend neurites, but BDNF does not appear to be necessary for maintaining the response once it is induced.     

The functional organisation of glia in the adult brain of Drosophila and other insects

This review annotates and categorises the glia of adult Drosophila and other model insects and analyses the developmental origins of these in the Drosophila optic lobe. The functions of glia in the adult vary depending upon their sub-type and location in the brain. The task of annotating glia is essentially complete only for the glia of the fly's lamina, which comprise: two types of surface glia—the pseudocartridge and fenestrated glia; two types of cortex glia—the distal and proximal satellite glia; and two types of neuropile glia—the epithelial and marginal glia. We advocate that the term subretinal glia, as used to refer to both pseudocartridge and fenestrated glia, be abandoned. Other neuropiles contain similar glial subtypes, but other than the antennal lobes these have not been described in detail. Surface glia form the blood brain barrier, regulating the flow of substances into and out of the nervous system, both for the brain as a whole and the optic neuropiles in particular. Cortex glia provide a second level of barrier, wrapping axon fascicles and isolating neuronal cell bodies both from neighbouring brain regions and from their underlying neuropiles. Neuropile glia can be generated in the adult and a subtype, ensheathing glia, are responsible for cleaning up cellular debris during Wallerian degeneration. Both the neuropile ensheathing and astrocyte-like glia may be involved in clearing neurotransmitters from the extracellular space, thus modifying the levels of histamine, glutamate and possibly dopamine at the synapse to ultimately affect behaviour.     

Training augments resistance exercise induced elevation of circulating brain derived neurotrophic factor (BDNF)

Brain derived neurotrophic factor (BDNF) is postulated to be an important mediator of exercise-induced neuroprotection. We tested the hypothesis that resistance exercise elevates circulating BDNF. Twenty healthy untrained college-aged males underwent a 5-week traditional or eccentric-enhanced progressive resistance training intervention. Blood was acquired at rest and 1, 30, and 60 min following a standardized resistance exercise testing bout performed at baseline and at the completion of the intervention. Serum BDNF responses did not differ between the two groups at any time point during baseline or post-intervention testing; thus, all values were combined into a single cohort for further analysis. Resting BDNF was not altered by the exercise training intervention [23,304 ± 1835 pg/ml (baseline) vs. 19,433 ± 1992 pg/ml (post-intervention)]. Following the baseline resistance exercise bout, serum BDNF increased 32% (p < 0.05) and was gradually reduced to 41% below resting levels at 60 min into recovery (p < 0.01). During post-intervention testing, serum BDNF increased 77% in response to the standardized resistance exercise bout (p < 0.01) and returned to resting values within 30 min. Ultimately, the change in serum BDNF from rest to immediately post-exercise was 98% greater at post-intervention than at baseline (p < 0.05). Our study is the first to demonstrate that resistance exercise induces a robust, yet transient, elevation of circulating BDNF and that progressive resistance training augments this response; perhaps demonstrating one mechanism through which exercise influences brain health.     

神经营养因子-3和胶质细胞衍生的神经营养因子共转导对小鼠耳蜗螺旋神经节细胞的保护作用

目的　探讨新型的病毒载体 (HSV Amplicon)介导的神经营养因子 3(NT 3)和胶质细胞衍生的神经营养因子 (GDNF)共同表达 ,对耳蜗螺旋神经节细胞 (SGNC)的保护作用。方法　构建能够在独自的转录控制条件下 ,同时表达NT 3和GDNF的HSV Amplicon重组体 (HSVnt 3myc/gdnf)。包装后 ,转导体外培养的内耳细胞 (MOI =1) ,4 8h后分别测定培养基中NT 3和GDNF的含量。建立顺铂 (DDP)致聋的小鼠动物模型 ,2 4只实验小鼠被分成 3组 ,经鼠尾静脉隔日注射DDP两次 ,8mg/kg ,4 8h后再分别经圆窗将 10 μlHSVnt 3myc/ gdnf、HSVnt 3myc/lac和HSVlac病毒悬液注入鼓阶 ,饲养 4周后 ,取出耳蜗 ,采用NIH软件分析系统 ,定量分析耳蜗内SGNC的总数。结果　ELISA显示HSVnt 3myc/gdnf转导的内耳细胞培养基中 ,NT 3的含量达 11 4 4 μg/ml,而GDNF的含量达 1 79ng/ml,与对照组比较 ,差异有显著意义 (P <0 0 1)。在DDP致聋的小鼠模型中 ,定向转染HSVnt 3myc/ gdnf、HSVnt 3myc/lac和HSVlac的耳蜗平均SGNC存活率分别为 88%、77%和2 2 % ,各组间差异有显著意义 (P <0 0 1)。结论　HSV Amplicon介导的NT 3/GDNF共同表达 ,可以刺激SGNC分泌NT 3和GDNF ,有效拮抗耳毒性药物所致的SGNC损伤 ,提高SGNC的残留数量 ,促进SGNC突起的再生。     

神经营养因子3在慢性应激诱发抑郁症的作用机制研究

目的探讨神经营养因子3在慢性应激诱发抑郁症过程中的作用机制。方法应用慢性不可预知的应激方式制作抑郁大鼠模型,采用蛋白质免疫印迹法、聚合酶链反应检测神经营养因子3蛋白和信使核酸(mRNA)的表达。结果实验后研究组大鼠的运动能力下降,体重显著低于对照组(t=15.47,P<0.001),这种变化持续于随后的整个造模期(t=18.73,P<0.001)。研究组大鼠神经营养因子3的蛋白和mRNA的表达均比对照组明显下降(P<0.001)。结论慢性应激后大鼠神经营养因子3的下调促进了神经元细胞凋亡。同时认为神经营养因子可能是通过磷酸肌醇3-激酶/Akt和Ras/MAPK途径调节神经元的凋亡。