NEUROBIOLOGIC STUDIES OF NEURONS AND GLIA IN CELL CULTURE

我们之前已经表明，慢性(&gt；24小时。)感官刺激 体外培养的神经元对生长激素的敏感性发生改变 电压敏感钙通道的刺激和下调 (VSCC)。我们现在在这一效果中表现出了特殊性，这两个方面都是 受影响的VSCC类型和不同的刺激模式。低谷 电压激活的VSCC(T电流)对刺激极为敏感； 以0.5赫兹的稳定频率进行单次刺激可完全消除T 电流大而不影响高压激活(N和L)的压控晶闸管。 相同数量的脉冲被组织成不同的破伤风模式 (‘突发性’)或稳定刺激对N和 L洋流。放射性标记的VSCC配体PN200-110的结合也是 慢性刺激下调细胞内钙离子的数量 经络受刺激的影响。培养骨骼的活化 含有乙酰胆碱的肌肉细胞产生凝血酶原mRNA的增加， 这与我们提出的凝血酶在血管中的作用是一致的。 依赖活动的突触消除过程。我们没有做到 证明丝氨酸蛋白酶抑制物蛋白连接蛋白的调节 然而，在肌肉方面，1。如果这种内源性抑制物确实在 突触的消除可能是因为它的存在(和调制) 在其他类型的细胞中，要么是神经细胞，要么是胶质细胞。关于PN 1‘S的证据 在神经胶质细胞中的存在和调节确实是通过 Brenneman在LDN的小组。 研究活动非依赖性指导的细胞定位 在发育中的视觉系统中，我们已经建立了视网膜和 在改良的三室室中进行顶盖培养。使用胚胎 我们已将之前确定的厌恶组件定位为 顶盖神经元。我们发现了一种可能是新颖的、积极的指导 放射状胶质细胞上的成分。这两种指导机制都是 在发育过程中仅限于顶盖的一部分。

We have previously shown that chronic (>24 hr.) stimulation of sensory neurons in vitro produces an alteration in growth cone sensitivity to stimulation and a down regulation of voltage-sensitive Ca++ channels (VSCC). We now show specificity in this effect both with regard to the type of VSCC affected and for different patterns of stimulation. The low voltage activated VSCC (T current) is extremely sensitive to stimulation; single stimuli at a steady rate of 0.5 Hz completely abolish the T current while not affecting the high voltage activated (N and L) VSCC. The same number of impulses organized into different patterns of tetanic ('bursty') or steady stimulations have differential effects on the N and L currents. Binding of a radio-labelled VSCC ligand, PN200-110 is also down regulated by chronic stimulation confirming that the number of Ca++ channels is affected by the stimulation. Activation of cultured skeletal muscle cells with acetylcholine produces an increase in prothrombin mRNA, which is consistent with the role we have proposed for thrombin in the process of activity dependent synapse elimination. We fail to demonstrate a modulation of the serine protease inhibitor Protease Nexin 1 in muscle, however. If this endogenous inhibitor does play a role in synapse elimination it may be because of its presence (and modulation) in some other cell type, either nerve or glia. Evidence for PN 1's presence and modulation in glia cells has indeed been obtained by Brenneman's group in the LDN. To investigate the cellular localization of activity-independent guidance cues in the developing visual system, we have established retinal and tectal cultures in modified 3-compartment chambers. Using embryonic chick we have localized a previously identified aversive component to tectal neurons. We have discovered a possibly novel, positive guidance component on radial glia. Both of these guidance mechanisms are restricted to one portion of the tectum during development.