Schomerus C, Laedtke E, Korf H W
Centre of Morphology, Johann Wolfgang Goethe University, Frankfurt/Main, Germany.
Neurochem Int. 1995 Aug;27(2):163-75. doi: 10.1016/0197-0186(95)00029-8.
Calcium responses of isolated rat pineal cells to noradrenergic, cholinergic and vasopressinergic stimulations were recorded by use of the fura-2 technique and an image analysis system. Subsequently the recorded cells were identified as pinealocytes by immunocytochemical demonstration of S-antigen, a pinealocyte-specific marker. S-antigen immunoreactive pinealocytes were shown to respond to norepinephrine stimulation with an elevation of the intracellular free calcium concentration ([Ca2+]i). This response was dose-dependent and consisted of a rapid increase in [Ca2+]i (primary phase) followed by a decrease to an elevated plateau well above the basal level (secondary phase). The plateau persisted for at least 1 h when cells were constantly exposed to norepinephrine and dropped to basal level upon removal of the stimulus. Analysis of the calcium responses of cells treated with caffeine or thapsigargin suggested that the primary phase reflects mobilization of calcium from inositol 1,4,5-trisphosphate-sensitive intracellular calcium stores. Depletion of these calcium stores was a decisive and sufficient prerequisite to evoke the secondary phase which was apparently elicited by calcium influx. These data suggest that a capacitative calcium entry is involved in pineal calcium signalling. Acetylcholine induced an increase in [Ca2+]i in rat pinealocytes. Experiments with different cholinergic agonists and antagonists provided evidence that the acetylcholine-induced calcium response was mediated via nicotinic acetylcholine receptors. Stimulation of isolated rat pineal cells with arginine-vasopressin caused a rise in [Ca2+]i in approx. 5% of the cells. However, these cells remained unidentified because they contained neither immunoreactive S-antigen nor immunoreactive glial fibrillary acidic protein, a marker for interstitial (glial) cells of the rat pineal organ. Taken together, the results underline the pivotal role of norepinephrine for the regulation of pineal signal transduction, but they also support the notion that other neurotransmitters and neuropeptides are involved in the modulation of pineal calcium signalling.
运用fura - 2技术和图像分析系统记录了分离的大鼠松果体细胞对去甲肾上腺素能、胆碱能和血管加压素能刺激的钙反应。随后，通过免疫细胞化学方法显示松果体细胞特异性标志物S - 抗原，将记录的细胞鉴定为松果体细胞。结果表明，S - 抗原免疫反应性松果体细胞对去甲肾上腺素刺激有反应，细胞内游离钙浓度（[Ca2 + ]i）升高。这种反应呈剂量依赖性，包括[Ca2 + ]i的快速增加（初级阶段），随后下降至远高于基础水平的升高平台期（次级阶段）。当细胞持续暴露于去甲肾上腺素时，平台期持续至少1小时，去除刺激后降至基础水平。对用咖啡因或毒胡萝卜素处理的细胞的钙反应分析表明，初级阶段反映了钙从肌醇1,4,5 - 三磷酸敏感的细胞内钙储存库中的动员。这些钙储存库的耗尽是引发次级阶段的决定性和充分前提条件，次级阶段显然是由钙内流引起的。这些数据表明，钙池调控性钙内流参与了松果体钙信号传导。乙酰胆碱可诱导大鼠松果体细胞内[Ca2 + ]i增加。使用不同胆碱能激动剂和拮抗剂的实验提供了证据，表明乙酰胆碱诱导的钙反应是通过烟碱型乙酰胆碱受体介导的。用精氨酸血管加压素刺激分离的大鼠松果体细胞，约5%的细胞内[Ca2 + ]i升高。然而，这些细胞未被鉴定，因为它们既不含有免疫反应性S - 抗原，也不含有免疫反应性胶质纤维酸性蛋白，后者是大鼠松果体器官间质（胶质）细胞的标志物。综上所述，这些结果强调了去甲肾上腺素在松果体信号转导调节中的关键作用，但也支持了其他神经递质和神经肽参与松果体钙信号调制的观点。
