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首页> 外文期刊>Cellular Physiology and Biochemistry >Evidence that IP3 and ryanodine-sensitive intra-cellular Ca2+ stores are not involved in acute hyposmotically-induced prolactin release in tilapia
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Evidence that IP3 and ryanodine-sensitive intra-cellular Ca2+ stores are not involved in acute hyposmotically-induced prolactin release in tilapia

机译：IP3和对ryanodine敏感的细胞内Ca2 +储存不参与罗非鱼急性下渗诱导的催乳激素释放的证据

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摘要

Prolactin (PRL) cells from the euryhaline tilapia, Oreochromis mossambicus, behave like osmoreceptors by responding directly to reductions in medium osmolatiy with increased secretion of the osmoregulatory hormone PRL. Extracellular Ca2+ is essential for the transduction of a hyposmotic stimulus into PRL release. In the current study, the presence and possible role of intracellular Ca2+ stores during hyposmotic stimulation was investigated using pharmacological approaches. Changes in intracellular Ca2+ concentration were measured with fura-2 in isolated PRL cells. Intracellular Ca2+ stores were depleted in dispersed PRL cells with thapsigargin (1 muM) or cyclopiazonic acid (CPA, 10 muM). Preincubation with thapsigargin prevented the rise in [Ca2+](i) induced lysophosphatidic acid (LPA, 1 muM), an activator of the IP3 signalling cascade, but did not prevent the hyposmotically-induced rise in [Ca2+](i) in medium with normal [Ca2+] (2 mM). Pre-treatment with CPA produced similar results. Prolactin release from dispersed cells followed a pattern that paralleled observed changes in [Ca2+](i). CPA inhibited LPA-induced prolactin release but not hyposmotically-induced release. Xestospongin C (1 muM), an inhibitor of IP3 receptors. had no effect on hyposmotically-induced PRL release. Pre-exposure to caffeine (10 mM) or ryanodine (1 muM) did not prevent a hyposmotically-induced rise in [Ca2+](i). Taken together these results indicate the presence of IP3 and ryanodine-sensitive Ca2+ stores in tilapia PRL cells. However, the rapid rise in intracellular [Ca2+] needed for acute PRL release in response to hyposmotic medium can occur independently of these intracellular Ca2+ stores. Copyright (C) 2004 S. Karger Ag, Basel .
机译：来自欧亚罗非鱼罗非鱼（Oreochromis mossambicus）的催乳素（PRL）细胞通过直接响应中等渗透压的降低和渗透压调节激素PRL的分泌增加而表现出类似渗透压感受器的作用。细胞外Ca2 +对于将低渗刺激转换为PRL释放至关重要。在当前的研究中，使用药理学方法研究了低渗刺激期间细胞内Ca2 +储存的存在和可能的作用。用呋喃2测定分离的PRL细胞中细胞内Ca2 +浓度的变化。细胞内的Ca2 +储存在枯草芽孢杆菌素（1μM）或环吡唑酸（CPA，10μM）中分散的PRL细胞中。与毒胡萝卜素的预温育可防止[Ca2 +]（i）诱导的溶血磷脂酸（LPA，1μM）的升高，这是IP3信号级联反应的激活剂，但不能阻止低钙诱导的[Ca2 +]（i）在含有以下成分的培养基中的升高：正常的[Ca2 +]（2 mM）。 CPA预处理产生了相似的结果。催乳素从分散的细胞中释放的模式与观察到的[Ca2 +]（i）变化平行。 CPA抑制LPA诱导的催乳激素释放，但不能抑制低渗诱导的释放。 Xestospongin C（1μM），一种IP3受体抑制剂。对低渗诱导的PRL释放没有影响。预先暴露于咖啡因（10 mM）或ryanodine（1μM）并不能防止低钙诱导的[Ca2 +]（i）升高。这些结果加在一起表明在罗非鱼PRL细胞中存在IP3和对精氨酸敏感的Ca2 +。但是，响应于低渗性介质，急性PRL释放所需的细胞内[Ca2 +]的快速升高可能独立于这些细胞内Ca2 +的储存而发生。版权所有（C）2004 S.Karger Ag，巴塞尔。

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