Schettini G, Koike K, Login I S, Judd A M, Cronin M J, Yasumoto T, MacLeod R M
Am J Physiol. 1984 Oct;247(4 Pt 1):E520-5. doi: 10.1152/ajpendo.1984.247.4.E520.
The marine dinoflagellate toxin maitotoxin (MTX), an activator of calcium channels, stimulates the release of prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH), and luteinizing hormone (LH) from monolayers of anterior pituitary cells in a dose-dependent manner. Maitotoxin significantly increased PRL, GH, and LH release within 1.5 min and TSH release within 3.5 min, and the stimulation continued for at least 1 h (P less than 0.01). MTX-stimulated hormonal release was blocked by the calcium channel blocker manganese (P less than 0.01). In freshly dispersed perifused pituitary cells in columns, exposure to MTX for 10 min markedly increased PRL, GH, TSH, and LH release for at least 1 h after withdrawal of the toxin. In other experiments, MTX significantly stimulated 45Ca2+ exchange by dispersed pituitary cells within 30 s, continuing for at least 30 min. We conclude that MTX increases anterior pituitary hormonal release, possibly by activating calcium channels, thereby increasing cellular calcium influx. Thus MTX may be a useful agent for investigating the involvement of Ca2+ in hormonal secretory processes.
海洋双鞭甲藻毒素——刺尾鱼毒素（MTX）是一种钙通道激活剂，它能以剂量依赖的方式刺激垂体前叶细胞单层释放催乳素（PRL）、生长激素（GH）、促甲状腺激素（TSH）和促黄体生成素（LH）。刺尾鱼毒素在1.5分钟内显著增加PRL、GH和LH的释放，在3.5分钟内增加TSH的释放，且这种刺激持续至少1小时（P<0.01）。MTX刺激的激素释放被钙通道阻滞剂锰阻断（P<0.01）。在柱中新鲜分散的灌流垂体细胞中，暴露于MTX 10分钟后，在撤除毒素后至少1小时内，PRL、GH、TSH和LH的释放显著增加。在其他实验中，MTX在30秒内显著刺激分散的垂体细胞进行45Ca2+交换，并持续至少30分钟。我们得出结论，MTX可能通过激活钙通道增加垂体前叶激素释放，从而增加细胞钙内流。因此，MTX可能是研究Ca2+在激素分泌过程中作用的有用试剂。
