Schulz W A, Gebhardt R, Mecke D
Eur J Biochem. 1985 Feb 1;146(3):549-53. doi: 10.1111/j.1432-1033.1985.tb08686.x.
Induction of ornithine decarboxylase by various hormones was studied in quiescent primary cultures of adult rat hepatocytes maintained in a chemically defined medium. The following results were obtained: Enzyme activity rose transiently during the first day of cultivation in hormone-untreated cells. During this phase, insulin increased ornithine decarboxylase activity. Inducibility by insulin was maintained for more than 40 h only after pretreatment with 0.1 microM dexamethasone. Enzyme activity could be induced by 1 nM insulin and peaked after 7 h. Inducibility by glucagon and growth hormone required pretreatment with the glucocorticoid hormone. Ornithine decarboxylase activity was maximal 5 h after glucagon addition. Concentrations down to 0.1 nM were effective. Pretreatment with dexamethasone was most effective, when the hormone was present during the first 20 h of cultivation. The effect of the glucocorticoid during the pretreatment phase was diminished by colchicine and to a lesser extent by cytochalasine B. We suggest that part of the permissive effect of dexamethasone could be mediated by changes in the cytoskeleton and the function of hormone receptors. The fact that induction of ornithine decarboxylase was exerted by several hormones despite the absence of cell proliferation and DNA synthesis may indicate that polyamine biosynthesis has an important role in the quiescent hepatocyte.
在化学成分明确的培养基中维持的成年大鼠肝细胞的静止原代培养物中，研究了各种激素对鸟氨酸脱羧酶的诱导作用。获得了以下结果：在未用激素处理的细胞培养的第一天，酶活性短暂上升。在此阶段，胰岛素增加了鸟氨酸脱羧酶的活性。仅在用0.1微摩尔地塞米松预处理后，胰岛素的诱导性才能维持超过40小时。1纳摩尔胰岛素可诱导酶活性，并在7小时后达到峰值。胰高血糖素和生长激素的诱导需要用糖皮质激素进行预处理。添加胰高血糖素后5小时，鸟氨酸脱羧酶活性最高。低至0.1纳摩尔的浓度也有效。当地塞米松在培养的前20小时存在时，预处理效果最佳。秋水仙碱可减弱预处理阶段糖皮质激素的作用，细胞松弛素B的减弱作用较小。我们认为，地塞米松的部分允许作用可能是由细胞骨架和激素受体功能的变化介导的。尽管没有细胞增殖和DNA合成，但几种激素仍能诱导鸟氨酸脱羧酶，这一事实可能表明多胺生物合成在静止肝细胞中具有重要作用。
