Przylipiak A F, Kiesel L, Karenberg T A, Przylipiak M S, Runnebaum B
Department of Obstetrics and Gynecology, University of Heidelberg, FRG.
Acta Endocrinol (Copenh). 1990 Oct;123(4):459-63. doi: 10.1530/acta.0.1230459.
Inositol 4,5-bisphosphate and inositol 1,4,5-trisphosphate, administered exogenously at a concentration of 3 x 10(-5) mol/l increased LH release in superfused rat pituitary cells by 950 +/- 267% and 281 +/- 83%, respectively. This stimulatory effect was reversible and dose-dependent. Other inositol phosphates (inositol 1-monophosphate, inositol 1,4,5,6-tetrakisphosphate, inositol 1,3,4,5,6-pentakisphosphate and inositol 1,2,3,4,5,6-hexakisphosphate), tested in vitro, did not significantly influence LH release. In saponin-permeabilized cells, the rate of basal and stimulated LH release was twice that in non-permeabilized cells. Penetration of inositol bisphosphate and inositol trisphosphate into saponin-treated pituitary cells did not increase the secretory potency of these agents compared with their effect on non-permeabilized cells. The new findings document that inositol trisphosphate formation occurs within 5-45 s after GnRH (10(-7) mol/l) administration and seems to be involved in mediating the rapid, first phase of LH release, whereas inositol bisphosphate formation occurs after 3-15 min and is probably related to later phases of LH secretion. Our results suggest that inositol bisphosphate and inositol trisphosphate are important regulators of the release of luteinizing hormone and can exert their effects not only intracellularly, but also extracellularly.
以3×10⁻⁵mol/L的浓度外源性给予肌醇4,5 - 二磷酸和肌醇1,4,5 - 三磷酸，可使体外灌流的大鼠垂体细胞中促黄体生成素（LH）释放分别增加950±267%和281±83%。这种刺激作用是可逆的且呈剂量依赖性。体外测试的其他肌醇磷酸酯（肌醇1 - 单磷酸、肌醇1,4,5,6 - 四磷酸、肌醇1,3,4,5,6 - 五磷酸和肌醇1,2,3,4,5,6 - 六磷酸）对LH释放没有显著影响。在皂角苷通透的细胞中，基础和刺激状态下LH释放的速率是非通透细胞中的两倍。与它们对非通透细胞的作用相比，肌醇二磷酸和肌醇三磷酸进入皂角苷处理的垂体细胞并没有增加这些物质的分泌效能。新的研究结果表明，在给予促性腺激素释放激素（GnRH，10⁻⁷mol/L）后5 - 45秒内会形成肌醇三磷酸，且似乎参与介导LH释放的快速第一阶段，而肌醇二磷酸的形成发生在3 - 15分钟之后，可能与LH分泌的后期阶段有关。我们的结果表明，肌醇二磷酸和肌醇三磷酸是促黄体生成素释放的重要调节因子，它们不仅可以在细胞内发挥作用，还能在细胞外发挥作用。
