Windle R J, Wood S A, Shanks N, Lightman S L, Ingram C D
Department of Anatomy, University of Bristol School of Medical Sciences, United Kingdom.
Endocrinology. 1998 Feb;139(2):443-50. doi: 10.1210/endo.139.2.5721.
The present study investigated the dynamic regulation of the hypothalamo-pituitary-adrenal axis and its significance to acute stress responsiveness in the female rat. An automated, frequent blood-sampling technique allowed the circadian rhythm of corticosterone to be resolved into a series of pulses. These were equally distributed (mean interval, 50.9 +/- 3.7 min) throughout the 24-h cycle, but their magnitude varied significantly, being higher between 1800-2200 h (137 +/- 9 ng/ml) than between 0600-1000 h (75 +/- 17 ng/ml). This pattern of release indicates continuous, but variable, activity of the axis throughout the day. The pulsatile ultradian rhythm suggested alternate periods of secretion and inhibition, which were found to have a profound effect on the corticosterone responses to acute stress. Noise stress (10 min, 114 decibels) evoked a transient increase in corticosterone, which reached a maximum (377 +/- 87 ng/ml) 20 min after onset. However, within this group (n = 26) the response varied depending on the underlying basal activity. When stress coincided with a rising (secretory) phase of a pulse, corticosterone concentrations rose to 602 +/- 150% of mean basal concentrations (P < 0.001). In contrast, when stress coincided with a falling (nonsecretory) phase of a pulse, a significantly smaller response, no greater than a basal pulse, was evoked. Thus, the alternate periods of secretion and inhibition generating basal hypothalamo-pituitary-adrenal activity are an important determinant of responses to acute stress.
本研究调查了雌性大鼠下丘脑-垂体-肾上腺轴的动态调节及其对急性应激反应性的意义。一种自动化的频繁采血技术使皮质酮的昼夜节律分解为一系列脉冲。这些脉冲在整个24小时周期内均匀分布（平均间隔为50.9±3.7分钟），但其幅度变化显著，在1800-2200时（137±9纳克/毫升）高于0600-1000时（75±17纳克/毫升）。这种释放模式表明该轴在一天中持续但可变地活动。脉动性超日节律提示存在交替的分泌期和抑制期，发现它们对皮质酮对急性应激的反应有深远影响。噪声应激（10分钟，114分贝）引起皮质酮短暂升高，在开始后20分钟达到最大值（377±87纳克/毫升）。然而，在该组（n = 26）中，反应因基础基础活动而异。当应激与脉冲的上升（分泌）期同时发生时，皮质酮浓度升至平均基础浓度的602±150%（P < 0.001）。相反，当应激与脉冲的下降（非分泌）期同时发生时，诱发的反应明显较小，不超过基础脉冲。因此，产生基础下丘脑-垂体-肾上腺活动的交替分泌期和抑制期是对急性应激反应的重要决定因素。
