Lipp K, van der Meulen N
Pediatr Res. 1977 Jun;11(6):705-9. doi: 10.1203/00006450-197706000-00001.
This investigation was designed to study specific glucocorticoid binding to cytoplasmic fraction and nuclei of thymus cells during rat development and to find out whether these data can be correlated to changes of RNA synthesizing activity of nuclei and cytoplasm. The dexamethasone binding capacity of cytoplasm rose rapidly in rats weighing up to 125 g and decreased significantly in animals weighing more than 160 g. Hormone binding to nuclei revealed similar but less pronounced changes. RNA synthesizing activity of nuclei measured by [3H]uridine incorporation in vitro decreased from 57 +/- 4.6 dpm/microng DNA in young to 23 +/- 2.2 dpm/microng DNA in adult rats. RNA synthesizing activity of the cytoplasmic fraction fell 21.6% and that of purified polymerase IIIB fell 27.8% during development. Inhibition of RNA synthesis by dexamethasone applied in vivo and in vitro showed age-dependent differences. The RNA synthesizing capacity of nuclei was inhibited up to 39% in animals weighing 130 g and only 9% in aging rats. Similar changes were observed by incubation of intact thymocytes with and without hormone. The observed inhibitory effect of dexamethasone on RNA synthesis is well correlated to changes of cytoplasmic hormone receptor capacities during development.
本研究旨在探讨大鼠发育过程中特定糖皮质激素与胸腺细胞胞质部分及细胞核的结合情况，并确定这些数据是否与细胞核和细胞质中RNA合成活性的变化相关。体重达125 g的大鼠，其胞质的地塞米松结合能力迅速上升，而体重超过160 g的动物则显著下降。激素与细胞核的结合呈现相似但不太明显的变化。通过体外[3H]尿苷掺入法测定，幼龄大鼠细胞核的RNA合成活性从57±4.6 dpm/μg DNA降至成年大鼠的23±2.2 dpm/μg DNA。发育过程中，胞质部分的RNA合成活性下降了21.6%，纯化的聚合酶IIIB下降了27.8%。体内和体外应用地塞米松对RNA合成的抑制表现出年龄依赖性差异。体重130 g的动物，细胞核的RNA合成能力被抑制高达39%，而老龄大鼠仅为9%。完整胸腺细胞在有或无激素情况下孵育也观察到类似变化。地塞米松对RNA合成的抑制作用与发育过程中胞质激素受体能力的变化密切相关。
