Abstract — In the present study, close spatial relationships between peripheral serotoninergic nerve elements and the musculature of the body in planaria Polycelis tenuis, Schmidtea mediterranea, and Girardia tigrina have been demonstrated using immunocytochemical and histochemical methods and a confocal laser scanning microscopy. Such a localization of serotoninergic neurons and their fibers indicates an important role of serotonin in the regulation of the muscle function in planaria. Investigation of the mechanisms of muscle contraction in planaria have shown that depolarization caused by high concentration of potassium ions (15–100 mM) and serotonin (10 –4 –10 –9 M) induced contractions of isolated muscle fibers of Procerodes littoralis. Dihydropyridine calcium channel blockers, nicardipine, nitrendipine, and nifedipine, inhibited contractions of muscles induced by potassium and serotonin suggesting the dependence of the muscle contraction on the extracellular calcium. Thapsigargin and cyclopiazonic acid decreased the number of muscle cells contracting in response to potassium ions, but did not influence the induction of the contractions by serotonin. Thus, the muscle contraction caused by serotonin did not depend on the intracellular calcium. The results provide evidence of the presence of different types of receptors and ion channels mediating the muscle contraction in planaria.

中文翻译：

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血清素在涡虫肌肉功能中的生理作用研究

摘要 — 在本研究中，已经使用免疫细胞化学和组织化学方法以及共聚焦激光扫描显微镜证明了外周血清素能神经元与细涡虫、地中海 Schmidtea 和 Girardia tigrina 中身体肌肉组织之间的密切空间关系。5-羟色胺能神经元及其纤维的这种定位表明5-羟色胺在调节涡虫肌肉功能中的重要作用。涡虫肌肉收缩机制的研究表明，由高浓度钾离子 (15–100 mM) 和血清素 (10 –4 –10 –9 M) 引起的去极化诱导了海角藻分离的肌肉纤维收缩。二氢吡啶类钙通道阻滞剂、尼卡地平、尼群地平和硝苯地平，抑制由钾和血清素诱导的肌肉收缩，表明肌肉收缩依赖于细胞外钙。毒胡萝卜素和环吡嗪酸减少了响应钾离子而收缩的肌肉细胞的数量，但不影响血清素对收缩的诱导。因此，由血清素引起的肌肉收缩不依赖于细胞内钙。结果提供了存在介导涡虫肌肉收缩的不同类型受体和离子通道的证据。但不影响血清素对收缩的诱导。因此，由血清素引起的肌肉收缩不依赖于细胞内钙。结果提供了存在介导涡虫肌肉收缩的不同类型受体和离子通道的证据。但不影响血清素对收缩的诱导。因此，由血清素引起的肌肉收缩不依赖于细胞内钙。结果提供了存在介导涡虫肌肉收缩的不同类型受体和离子通道的证据。