Functional morphology of excitable glial nets associated with sensory nerve endings-calcium image analysis.

最近的研究表明，神经胶质细胞通过胞内Ca^2+浓度的瞬时升高来响应各种刺激，并且这些信号介导神经胶质细胞的活动以调节神经元的功能。在皮肤感觉器中，神经胶质细胞通过分支突起相互连接，形成一个网络，在不同的轴突终末之间延伸。为了确定时空动态和生理特性的细胞信号在这些神经胶质细胞网，钙图像孤立的披针形末梢，运动受体的大鼠触须，监测通过延时共聚焦显微镜，而细胞被刺激的神经递质腺苷5 '-三磷酸（ATP）的应用程序，或通过触摸与显微操作器驱动的玻璃针。电镜下观察胶质细胞信号的形态学背景。用ATP刺激引起神经胶质细胞内Ca^2+浓度的振荡性升高。他们的反应 ...更多信息 覆盖轴突终末的板层突起总是向胞体内的板层突起延伸。在每个薄片中，由给定的刺激试验引起的初始波来自细胞突起内的特定位点。用玻璃针接触披针形细胞会触发受影响的神经胶质层中的Ca^2+峰值。偶尔，Ca^2+波会在胶质细胞内部和胶质细胞之间传播，进入包裹着相邻披针叶细胞的其他胶质突起。这些研究结果意味着亚细胞区室化，可能使每个胶质细胞板层通过自己的钙信号调节其伴随的披针形终端的活动，以及通过板层间信号传播调节相邻的披针形。药理学实验表明，神经胶质细胞的ATP诱发反应是由嘌呤受体亚型P2Y_2介导的，P2Y_2的激活可诱导细胞内Ca^2+的释放。电镜观察到披针形的胶质细胞膜，其内部存在着储存Ca^2+的滑面内质网和可能参与细胞间信号传递的缝隙连接。少

Recent studies have shown that glial cells respond to various stimuli by a transient elevation in the intracellular Ca^<2+> concentration, and that these signals mediate glial activities to regulate neuronal functions. In cutaneous sensory devices, glial elements connect with each other by branched processes to form a network extending among different axon terminals. In order to define spatiotemporal dynamics and physiological properties of the cell signals in these glial nets, calcium images of isolated lanceolate endings, motion receptors of rat vibrissae, were monitored by time-lapse confocal microscopy while the cells were stimulated by application of the neurotransmitter adenosine 5'-triphosphate (ATP), or by touching with a micromanipulator-driven glass needle. Morphological backgrounds of the glial signaling were observed electron microscopically. Stimulation with ATP evoked an oscillatory elevation in the intracellular Ca^<2+> concentration in the glial cells. Responses in thei … More r lamellar processes covering axon terminals always proceeded to those in their cell bodies. In each lamella, the initial wave evoked by a given trial of the stimulant arose from a specific locus within the cell process. Touching with a glass needle on lanceolates triggered a Ca^<2+> spike in the affected glial lamellae. The Ca^<2+> waves occasionally traveled within, and between the glial cells, to enter other glial processes enveloping neighboring lanceolates. These findings imply subcellular compartmentalization that may enable each glial lamella to modulate the activity of its accompanying lanceolate terminal through its own Ca signal as well as to regulate neighboring lanceolates through interlamellar signal propagation. Pharmacological experiments have shown that the ATP-evoked responses of the glia are mediated by the purinoceptor subtype P2Y_2, activation of which induces Ca^<2+> release from an intracellular store. Gliai lamellae of lanceolate endings examined by electron microscopy revealed smooth endoplasmic reticulum which would store Ca^<2+> in the lumen, and gap junctions which maybe involved in the intercellular signal propagation. Less