Simon C, Gronfier C, Schlienger J L, Brandenberger G
Laboratoire des Régulations Physiologiques et des Rythmes Biologiques chez l'Homme, Strasbourg, France.
J Clin Endocrinol Metab. 1998 Jun;83(6):1893-9. doi: 10.1210/jcem.83.6.4864.
To determine the influence of circadian rhythmicity and sleep on the 24-h leptin diurnal variations, plasma leptin levels were measured at 10-min intervals over 24 h in seven normal subjects, once during nocturnal sleep, and once after an 8-h shift of sleep. The subjects were submitted to constant conditions (continuous enteral nutrition and bed rest in controlled chambers). Body temperature and plasma glucose and insulin levels were measured simultaneously. During nighttime sleep, leptin levels increased to a maximum (109.9 +/- 2.5% of the 24-h mean) and then decreased to reach a nadir in the late afternoon. The mean diurnal variation was 18.0 +/- 3.8% of the 24-h mean. In the daytime sleep condition, leptin levels rose during the night of deprivation to a maximum of 104.7 +/- 2.3% of the 24-h mean, decreased to a minimum around 0700 h, and then rose again during diurnal sleep (108.4 +/- 3.1% of the 24-h mean); the mean diurnal variation was 13.4 +/- 3.6% of the 24-h mean. ANOVA revealed a significant interaction between time of day and sleep effects (P < 0.05). The diurnal and the sleep-related variations of plasma leptin mirrored those of body temperature and roughly paralleled those of plasma glucose and insulin; the amplitudes of the diurnal leptin variations were significantly correlated with the amplitudes of the diurnal body temperature variations (P < 0.05). Plasma leptin levels also displayed irregular pulses of low amplitude (mean duration, 70 min) that were not affected by sleep, but were associated with a significant decrease in glucose and insulin levels (P < 0.01). These results demonstrate that under continuous enteral nutrition, plasma leptin levels are modulated by both a slight circadian component and sleep, which interact under normal conditions, and suggest that leptin is implicated in circadian thermoregulatory adjustments.
为了确定昼夜节律和睡眠对瘦素24小时昼夜变化的影响，对7名正常受试者在24小时内每隔10分钟测量一次血浆瘦素水平，一次在夜间睡眠期间，一次在睡眠8小时后进行。受试者处于恒定条件下（在可控室内持续肠内营养和卧床休息）。同时测量体温、血浆葡萄糖和胰岛素水平。夜间睡眠期间，瘦素水平升高至最高值（为24小时平均值的109.9±2.5%），然后下降，在傍晚时分降至最低点。平均昼夜变化为24小时平均值的18.0±3.8%。在白天睡眠条件下，瘦素水平在剥夺睡眠的夜间升高至24小时平均值的最高值104.7±2.3%，在0700时左右降至最低值，然后在日间睡眠期间再次升高（为24小时平均值的108.4±3.1%）；平均昼夜变化为24小时平均值的13.4±3.6%。方差分析显示，一天中的时间和睡眠效应之间存在显著交互作用（P<0.05）。血浆瘦素的昼夜变化和与睡眠相关的变化反映了体温的变化，大致与血浆葡萄糖和胰岛素的变化平行；昼夜瘦素变化的幅度与昼夜体温变化的幅度显著相关（P<0.05）。血浆瘦素水平还显示出低幅度的不规则脉冲（平均持续时间为70分钟），这些脉冲不受睡眠影响，但与葡萄糖和胰岛素水平的显著降低有关（P<0.01）。这些结果表明，在持续肠内营养的情况下，血浆瘦素水平受轻微的昼夜节律成分和睡眠的调节，它们在正常条件下相互作用，并提示瘦素参与昼夜体温调节调整。
