Michaud N J, Burton A F
Biol Neonate. 1977;32(3-4):132-7. doi: 10.1159/000241006.
Corticosterone in fetal mouse tissues after injection of mothers with 14C-corticosterone was determined by acetylation with 3H-acetic anhydride and cocrystallization to constant specific activity. The corticosterone content of whole fetal tissue varied between gestational days 13 and 17 from 641 to 300 ng/g. Specific activity of fetal hormone remained essentially constant; after a 15-min pulse this was as much as one-quarter that of maternal hormone. Placenta, head and liver showed distinctly different patterns which changed during this time, with a decrease in conversion of corticosterone to 11-dehydrocorticosterone. A sharp increase occurred in the activity of fetal liver 11beta-hydroxysteroid:NADP oxidoreductase activity. This mitochondrial enzyme, pH optimum 6, KM = 33 micrometer, reduced the metabolite, raising the relative amount of corticosterone in the fetus from 16 to 91%. 1 day after removal of maternal adrenals both maternal and fetal corticosterone were normal, indicating ability of fetal adrenals to function. Maternal corticosterone, however, crossed the placenta readily and it is considered likely that, normally, the maternal hormone predominates. Regardless of origin, corticosterone is maintained by enzymatic conversion in a distinct manner in different tissues.
给孕鼠注射14C-皮质酮后，通过用3H-乙酸酐乙酰化并共结晶至恒定比活度来测定胎鼠组织中的皮质酮。在妊娠第13至17天，整个胎鼠组织中的皮质酮含量在641至300 ng/g之间变化。胎鼠激素的比活度基本保持恒定；在15分钟的脉冲后，其比活度高达母体激素的四分之一。胎盘、头部和肝脏呈现出明显不同的模式，且在此期间发生变化，皮质酮向11-脱氢皮质酮的转化率降低。胎鼠肝脏11β-羟基类固醇：NADP氧化还原酶活性急剧增加。这种线粒体酶，最适pH为6，KM = 33微米，还原了代谢产物，使胎鼠体内皮质酮的相对含量从16%提高到91%。去除母体肾上腺1天后，母体和胎鼠的皮质酮均正常，表明胎鼠肾上腺具有功能。然而，母体皮质酮很容易穿过胎盘，据认为通常母体激素占主导地位。无论来源如何，皮质酮在不同组织中通过酶促转化以独特的方式得以维持。
