Zaplatosch Mitchell E, Wideman Laurie, McNeil Jessica, Sims Jesse N L, Adams William M
Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, Mailing address: P.O. Box 26170 Greensboro, NC, 27402-6170, USA.
Department of Exercise and Sports Management, Kennesaw State University, Mailing address: Prillaman Health Sciences Room 4025, Mail Drop 4104, 520 Parliament Garden Way NW, Kennesaw, GA, 30144-5591, USA.
Compr Psychoneuroendocrinol. 2025 Jan 2;21:100281. doi: 10.1016/j.cpnec.2024.100281. eCollection 2025 Feb.
Previous studies have identified links between fluid intake, hydration related hormones and cortisol measured at one timepoint but have not considered how hydration may influence cortisol dynamics throughout the day. This study assessed associations between hydration status (copeptin, urinary osmolality, urine volume) and habitual fluid intake with cortisol dynamics.
The day before (DB) a 6-h laboratory visit, 29 male participants (age, 23±4y; BMI, 25.5 ± 4.3 kg/m; body fat, 17.3 ± 9.3 %) provided 24-h urine samples and a fasted blood sample for hydration status assessment, recorded their 24-h fluid intake for three days prior, and provided 10 saliva samples to assess cortisol dynamics from DB into the evening of the laboratory visit. Calculated indices of cortisol dynamics included: nocturnal cortisol rise (NCR - salivary cortisol rise from bed to awakening), peak salivary cortisol (peak S - highest cortisol of all samples), cortisol awakening response (ΔCAR - difference between high morning sample and awakening sample), area under the curve with respect to ground (AUCG) and increase (AUCI), and diurnal cortisol slope (DCS - rate of change in cortisol from awakening to bed). The relationships between fluid intake or hydration status and cortisol dynamics were analyzed by separating participants into fluid intake tertile groups and by regressing cortisol dynamics on the continuous variables of total fluid intake (TFI) or hydration biomarkers.
There were no between-group differences for ΔCAR (p = 0.89), AUCG (p = 0.57), AUCI (p = 0.48), peak S (p = 0.14), NCR (p = 0.95), DCS (p = 0.22), or serum cortisol (p = 0.61). TFI was not associated with log (peak S) (p = 0.49), ΔCAR (p = 0.61), AUCG (p = 0.76), or AUCI (p = 0.56). Copeptin was not associated with log (peak S) (p = 0.99), ΔCAR (p = 0.22), AUCG (p = 0.69) or AUCI (p = 0.18). Urinary hydration markers were not associated with any measures of cortisol dynamics (p > 0.05). These null effects were consistent when controlling for physical activity, sleep, and body fat percentage.
In the absence of dehydrating stimuli, measures of fluid intake or hydration status may not be associated with cortisol dynamics in young healthy males.
以往研究已确定在某一时刻测量的液体摄入量、与水合作用相关的激素和皮质醇之间的联系，但尚未考虑水合作用如何在一整天中影响皮质醇动态变化。本研究评估了水合状态（ copeptin、尿渗透压、尿量）和习惯性液体摄入量与皮质醇动态变化之间的关联。
在进行6小时实验室访视的前一天（DB），29名男性参与者（年龄23±4岁；体重指数25.5±4.3kg/m；体脂17.3±9.3%）提供24小时尿液样本和一份空腹血样用于水合状态评估，记录他们在之前三天的24小时液体摄入量，并提供10份唾液样本以评估从DB到实验室访视当晚的皮质醇动态变化。计算得出的皮质醇动态变化指标包括：夜间皮质醇升高（NCR——从卧床到醒来时唾液皮质醇升高）、唾液皮质醇峰值（peak S——所有样本中的最高皮质醇）、皮质醇觉醒反应（ΔCAR——早晨高值样本与觉醒样本之间的差值）、相对于基线的曲线下面积（AUCG）和增加量（AUCI）以及昼夜皮质醇斜率（DCS——从醒来至卧床时皮质醇的变化率）。通过将参与者分为液体摄入量三分位数组，并将皮质醇动态变化指标对总液体摄入量（TFI）或水合生物标志物的连续变量进行回归分析，来分析液体摄入量或水合状态与皮质醇动态变化之间的关系。
ΔCAR（p = 0.89）、AUCG（p = 0.57）、AUCI（p = 0.48）、peak S（p = 0.14）、NCR（p = 0.95）、DCS（p = 0.22）或血清皮质醇（p = 0.61）在组间无差异。TFI与log（peak S）（p = 0.49）、ΔCAR（p = 0.61）、AUCG（p = 0.76）或AUCI（p = 0.56）无关。Copeptin与log（peak S）（p = 0.99）、ΔCAR（p = 0.22）、AUCG（p = 0.69）或AUCI（p = 0.18）无关。尿液水合标志物与任何皮质醇动态变化指标均无关（p>0.05）。在控制身体活动、睡眠和体脂百分比时，这些无效效应是一致的。
在没有脱水刺激的情况下，液体摄入量或水合状态指标可能与年轻健康男性的皮质醇动态变化无关。
