ADRENAL SENSITIVITY TO ADRENOCORTICOTROPIN VARIES DIURNALLY
ADRENAL SENSITIVITY TO ADRENOCORTICOTROPIN VARIES DIURNALLY
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DOI：
10.1210/endo-109-1-70
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发表时间：
1981-01-01
期刊：
影响因子：
4.8
通讯作者：
DALLMAN, MF
中科院分区：
文献类型：
--
作者：
KANEKO, M;KANEKO, K;DALLMAN, MF
为了进一步描述肾上腺对ACTH反应性昼夜节律的变化，我们测量了ACTH分布体积、代谢清除率和T1/2。在未经处理、地塞米松预处理或去垂体组的雌性大鼠中，这些指标在早晚之间没有变化。为了研究肾上腺对ACTH反应性改变的本质，地塞米松预处理的大鼠在早晨和晚上分别灌输不同剂量的ACTH 2小时。肾上腺对最大刺激肾上腺的ACTH输注速率的反应(200pg/100g体重)。Min)早晚相同，说明肾上腺容量没有变化。以较低的速率输注ACTH(50-100 pg/100 g体重)。Min)显示，类固醇反应曲线的斜率在早晚之间增加，表明肾上腺对ACTH的敏感性存在昼夜变化。这些结果和以前的数据一起表明，肾上腺cAMP对ACTH的反应的大小和时间过程强烈地表明，ACTH受体的亲和力或与腺苷环化酶的偶联是每天变化的。在其他实验中，对年轻和成年雄性和成年雌性未处理的大鼠进行了血浆ACTH和皮质酮水平的测定，这些大鼠每隔4小时全天候被杀。ACTH对ACTH的敏感度在熄灯时达到峰值，在点亮时达到谷值，表明实验证实的节律正常发生。
To further characterize diurnal changes in the rhythm in adrenal responsiveness to ACTH, ACTH distribution volume, MCR [metabolic clearance rate], and t1/2 were measured. These did not change between morning and evening in groups of untreated, dexamethasone-pretreated or hypophysectomized female rats. To characterize the nature of the change in adrenal responsiveness to ACTH, dexamethasone-pretreated rats were infused for 2 h with a variety of doses of ACTH in the morning and evening. The adrenal response to an infusion rate of ACTH that maximally stimulated the adrenals (200 pg/100 g body wt .cntdot. min) was the same in the morning and evening, showing that adrenal capacity does not change. ACTH infusion at lower rates (50-100 pg/100 g body wt .cntdot. min) revealed that the slope of the steroid response curve increased between morning and evening, demonstrating a diurnal change in adrenal sensitivity to ACTH. These results together with previous data showing that the magnitude and time course of the adrenal cAMP response to ACTH changes diurnally strongly suggest that ACTH receptor affinity or coupling with adenylate cyclase changes diurnally. In other experiments, plasma ACTH and corticosterone levels were determined in groups of young and adult male and adult female untreated rats killed at 4-h intervals around the clock. Peak sensitivity to ACTH was found at lights-out and trough sensitivity was found at lights-on, suggesting that the experimentally demonstrated rhythm occurs normally.