镧离子对大鼠垂体细胞合成与释放β－内啡肽的影响

Effects of Lanthanum Ion on Beta-Endorphin Biosynthesis and Release in Rat Pituitary Cells

采用无血清原代培养大鼠垂体细胞的方法，研究镧离子（Ｌａ^（３＋））对大鼠垂体细胞合成和释放β－内啡肽（β－ＥＰ）的影响。当细胞培养液中的Ｌａ^（３＋）浓度为１０^（－５）、１０^（－７）和１０^（－９）ｍｏｌ／Ｌ时可促进垂体前叶和中／后叶细胞释放β－ＥＰ，并增加细胞内β－ＥＰ含量。本文结果为阐明镧离子的镇痛作用机制进一步提供了细胞水平的实验依据。

By using the primary culture method for pituitary cells in CSFM established in our laboratory,we studied the effects of lanthanum ion (La3+)on the biosynthesis and release of β-endorphin-like immunoreactive substances in rat pituitary cells. Anterior and intermediate/posterior pituitary cells from male rats were cultured with arachidonic acid(AA),cortisol,dexamethasone(DEX ) and lanthanum chloride. RIA was used to determine β-EP levels in culture medium and within cells. The results indicated that AA could obviously stimulate the release of β-EP from pituitary cells at a concentration of 2×10-5mol/L, while cortisol at 10-6mol/L and DEX at 10-7 mol/L inhibited this release. These data coincide with results reported in the literature and thereby prove the reliability of the method used. When incubated with pituitary cells, lanthanum chloride induced a dose-and time-dependent release of β-EP.Namely,β-EP release continuously increased for a period under the action of La3+ of different doses(10-5 mol/L and 10￣(-7) mol/L).β-EP content in cells showed similar changes.These results suggest that β-EP biosynthesis and release in rat anterior and intermediate/posterior pituitary cells are stimulated by lanthanum ions.They also provide experimental evidence for explaining the analgesic mechanism of lanthanum ions at the cellular level.