Chapotot F, Gronfier C, Jouny C, Muzet A, Brandenberger G
Laboratoire des Régulations Physiologiques et des Rythmes Biologiques chez l'Homme, Institut de Physiologie, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
J Clin Endocrinol Metab. 1998 Dec;83(12):4263-8. doi: 10.1210/jcem.83.12.5326.
To determine whether human hypothalamo-pituitary-adrenal axis activity is related to the alertness level during wakefulness, 10 healthy young men were studied under resting conditions in the daytime (0900-1800 h) after an 8-h nighttime sleep (2300-0700 h). A serial 70-sec gaze fixation task was required every 10 min throughout the daytime experimental session. The corresponding waking electroencephalographic (EEG) segments were submitted to quantitative spectral analysis, from which EEG beta activity (absolute power density in the 13-35 Hz frequency band), an index of central alertness, was computed. Blood was collected continuously through an indwelling venous catheter and sampled at 10-min intervals. Plasma cortisol concentrations were measured by RIA, and the corresponding secretory rates were determined by a deconvolution procedure. Analysis of individual profiles demonstrated a declining tendency for EEG beta activity and cortisol secretory rate, with an overall temporal relationship indicated by positive and significant cross-correlation coefficients between the two variables in all subjects (average r=0.565, P < 0.001). Changes in cortisol secretion lagged behind fluctuations in EEG beta activity, with an average delay of 10 min for all the subjects. On the average, 4.6+/-0.4 cortisol secretory pulses and 4.9+/-0.5 peaks in EEG beta activity were identified by a detection algorithm. A significant, although not systematic, association between the episodes in the two variables was found: 44% of the peaks in EEG beta activity (relative amplitude, near 125%; P < 0.001) occurred during an ascending phase of cortisol secretion, cortisol secretory rates increasing by 40% (P < 0.01) 10-min after peaks in EEG beta activity. However, no significant change in EEG beta activity was observed during the period from 50 min before to 50 min after pulses in cortisol secretion. In conclusion, the present study describes a temporal coupling between cortisol release and central alertness, as reflected in the waking EEG beta activity. These findings suggest the existence of connections between the mechanisms involved in the control of hypothalamo-pituitary-adrenal activity and the activation processes of the brain, which undergoes varying degrees of alertness throughout daytime wakefulness.
为了确定人类下丘脑 - 垂体 - 肾上腺轴活动是否与清醒时的警觉水平相关，在夜间睡眠8小时（23:00 - 07:00）后的白天静息条件下（09:00 - 18:00）对10名健康年轻男性进行了研究。在整个白天的实验过程中，每隔10分钟需要进行一次连续70秒的注视固定任务。对相应的清醒脑电图（EEG）片段进行定量频谱分析，从中计算出EEGβ活动（13 - 35Hz频段的绝对功率密度），这是中枢警觉性的一个指标。通过留置静脉导管持续采集血液，并每隔10分钟取样一次。用放射免疫分析法测定血浆皮质醇浓度，并通过反卷积程序确定相应的分泌率。对个体数据的分析表明，EEGβ活动和皮质醇分泌率呈下降趋势，所有受试者中这两个变量之间的正相关且显著的交叉相关系数表明了总体的时间关系（平均r = 0.565，P < 0.001）。皮质醇分泌的变化滞后于EEGβ活动的波动，所有受试者的平均延迟为10分钟。平均而言，通过检测算法识别出4.6±0.4个皮质醇分泌脉冲和4.9±0.5个EEGβ活动峰值。发现两个变量的发作之间存在显著但不系统的关联：EEGβ活动峰值的44%（相对幅度，接近125%；P < 0.001）发生在皮质醇分泌的上升阶段，在EEGβ活动峰值后10分钟，皮质醇分泌率增加40%（P < 0.01）。然而，在皮质醇分泌脉冲前50分钟至后50分钟期间，未观察到EEGβ活动有显著变化。总之，本研究描述了皮质醇释放与中枢警觉性之间的时间耦合，这在清醒EEGβ活动中得到体现。这些发现表明，参与下丘脑 - 垂体 - 肾上腺活动控制的机制与大脑的激活过程之间存在联系，大脑在白天清醒期间经历不同程度的警觉。
