PURPOSE The aims of our study were to determine first circadian influences on central concentrations of the neuropeptides oxytocin and arginine-vasopressin and second to investigate if these central concentrations are associated with those in the peripheral compartments blood and saliva in neurocritical care patients. We therefore included patients with external ventricular drain who attended a neurosurgical intensive care unit and were not exposed to painful or stressful stimuli during the sampling period. For this purpose, blood, cerebrospinal fluid and saliva were collected in a 24-hour-interval at the timepoints 06:00, 12:00, 18:00 and 24:00. RESULTS In none of the three body fluids examined, significant time-dependent fluctuations of oxytocin and arginine-vasopressin concentrations could be detected during the 24-hour sampling period. The only exception was the subgroup of postmenopausal women whose oxytocin concentrations in cerebrospinal fluid at 12:00 were significantly higher than at 18:00. Correlations of blood and cerebrospinal fluid and blood and saliva neuropeptide levels were very weak to weak at each timepoint. Cerebrospinal fluid and saliva oxytocin levels showed a moderate correlation at 06:00 but did correlate very weak at the other timepoints. CONCLUSIONS Central as well as peripheral oxytocin and arginine-vasopressin concentrations in neurocritical care patients did not show significant diurnal fluctuations. No strong correlations between central and peripheral neuropeptide concentrations could be detected under basal conditions. If investigators even though decide to use saliva concentrations as surrogate parameter for central neuropeptide activity, they have to consider that correlations of cerebrospinal fluid and saliva oxytocin seem to be highest in the early morning.

中文翻译：

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人脑脊液、血液和唾液中不存在催产素和精氨酸加压素的昼夜节律

目的我们研究的目的首先是确定昼夜节律对神经肽催产素和精氨酸加压素的中心浓度的影响，其次是研究这些中心浓度是否与神经重症监护患者的外周隔室血液和唾液中的浓度有关。因此，我们纳入了在神经外科重症监护室就诊且在采样期间未暴露于疼痛或压力刺激的心室外引流患者。为此，在时间点 06:00、12:00、18:00 和 24:00 每隔 24 小时收集血液、脑脊液和唾液。结果 在所检查的三种体液中，在 24 小时采样期间均未检测到催产素和精氨酸-加压素浓度随时间的显着波动。唯一的例外是绝经后妇女亚组，其 12:00 脑脊液中的催产素浓度显着高于 18:00。在每个时间点，血液和脑脊液以及血液和唾液神经肽水平的相关性非常弱到弱。脑脊液和唾液催产素水平在 06:00 显示出中等相关性，但在其他时间点的相关性非常弱。结论 神经重症监护患者的中枢和外周催产素和精氨酸 - 加压素浓度没有显示出明显的昼夜波动。在基础条件下没有检测到中枢和外周神经肽浓度之间的强相关性。如果研究人员即使决定使用唾液浓度作为中枢神经肽活性的替代参数，