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Changes in diurnal rhythms of free cortisol secretion during different phases of menstrual cycle

Bao Aimin, Liu Rongyu, Eus J. W. Van Someren, Michel A. Hofman, Zhou Jiangning

Department of Neurobiology, School of Life Science, University of Science and Technology of China. Hefei 230032，Anhui,China；Anhui Geriatrics Institute, The First Affiliated Hospital of Anhui Medical University, Hefei 230022，Anhui,China；Netherlands Institute for Brain Research, 1105 AZ Amsterdam ZO, The Netherlands

Abstract

The effect of the menstrual cycle on the diurnal cortisol rhythm was investigated in 15 normally cyclic healthy women during reproductive life. Salivary cortisol was measured by radioimmunoassay in samples collected every 2 h for 24 h during the four phases of the menstrual cycle: menstrual phase, late follicular/peri-ovulation phase, early to mid luteal phase and late luteal phase, respectively. Distinct diurnal rhythms of free cortisol were found throughout the menstrual cycle by using a nonlinear periodic regression model. The model was characterized by an asymmetrically peaked diurnal cycle and ultradian harmonics. There was a trend to higher troughs and significantly shorter peak-width in phase Ⅱ and phase Ⅳ compared to phase Ⅰ . The ultradian amplitude in phase Ⅳ was significantly lower compared with phase I and showed a trend of decrease compared with phase Ⅱ. The results suggest that the daily cortisol secretion is modulated by the phase of the menstrual cycle.

Key words: Diurnal rhythm;Ultradian rhythm;Free cortisol;Menstrual cycle;Saliva

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Citing This Article：

Bao Aimin, Liu Rongyu, Eus J. W. Van Someren, Michel A. Hofman, Zhou Jiangning. Changes in diurnal rhythms of free cortisol secretion during different phases of menstrual cycle. Acta Physiol Sin 2003; 55 (5): (in Chinese with English abstract).