ELEMENTAL AND STRUCTURAL ORGANIZATION OF NEURONS AND GLIA

本项目研究钙的生理和发育 在树突和树突的突触活动过程中的调节 中枢神经系统神经元的棘。 此前，分析和 使用一种新型海马切片培养物进行结构工作， 其特征在于内质网的一个子集作为主要的钙离子- CA3区神经元树突内的隔离细胞器 在传入突触活动之后。 我们现在已经确定， 这些钙缓冲细胞器非常相似，如果不是相同的话， 到那些在其他时候作为钙的储存和释放 细胞器发现这些细胞器起着钙离子的作用 在<1 - 15分钟的时间范围内， 线粒体钙螯合作用与ER摄取平行 仅在突触活动后的第一分钟内。类似的证据 对于强大的线粒体钙螯合已经从 蛙交感神经节分离神经元的新研究 以前我们已经证明雌二醇使树突棘密度加倍 在CA1海马神经元的培养中，从而提供了一种有吸引力的 解释最近发现雌激素影响认知， 在成年生物体中的可塑性。使用激酶抑制剂的新实验， 反义寡核苷酸和特异性抗体， 高分辨率共聚焦显微镜显示， 元件结合蛋白（CREB）必须通过cAMP磷酸化- 依赖性蛋白激酶A和CREB结合蛋白（CBP）被募集， 在脊柱发育之前。这表明，基因组激活， 转录刺蛋白可能是新刺发育所必需的。在 通过对雌二醇间接作用的平行实验，发现 这种激素可以降低谷氨酸脱羧酶（GAD）的抑制作用 海马中间神经元，从而减少数量和可用性 神经递质γ-氨基丁酸这实际上改变了 锥体神经元的兴奋/抑制，增加细胞内 钙，这可能反过来导致磷酸化CREB和合成 新的刺。研究结果表明， 雌二醇可以提供一种强有力但短暂的方式来控制兴奋性 活性和形态可塑性。

This project studies the physiology and development of calcium regulation during synaptic activity in the dendrites and dendritic spines of central nervous system neurons. Previously, analytical and structural work using a new type of hippocampal slice culture had characterized a subset of endoplasmic reticulum as the major calcium- sequestering organelle in dendrites of CA3 neurons in the minutes following the afferent synaptic activity. We have now established that these calcium-buffering organelles are very similar, if not identical, to those which at other times act as calcium storage and release organelles. It is found that these organelles function as calcium sequestration sites within a time frame of <1-15 minutes, while mitochondrial calcium sequestration operates in parallel with ER uptake only over the first minute following synaptic activity. Similar evidence for robust mitochondrial calcium sequestration has been obtained from a new study on isolated neurons from frog sympathetic ganglia. Previously we had shown that estradiol doubles dendritic spine density in cultures of CA1 hippocampal neurons, thus providing an attractive explanation for the recent discovery that estrogen affects cognition and plasticity in adult organisms. New experiments using kinase inhibitors, antisense oligonucleotides, and specific antibodies in combination with high-resolution confocal microscopy now show that the cAMP response element binding protein (CREB) is necessarily phosphorylated via cAMP- dependent protein kinase A, and CREB binding protein (CBP) is recruited, prior to spine development. This indicates that genome activation to transcribe spine proteins may be required for new spine development. In parallel experiments on the indirect effects of estradiol, it was found that this hormone lowers glutamic acid decarboxylase (GAD) in inhibitory hippocampal interneurons, thus decreasing the amount and availability of the neurotransmitter GABA. This effectively changes the balance of excitation/inhibition in pyramidal neurons, increasing intracellular calcium which may in turn cause phosphorylation of CREB and synthesis of new spines. The findings suggest that the indirect effects of estradiol can provide a powerful yet transient way to control excitatory activity and morphological plasticity.