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Sex differences in the circadian profiles of melatonin and cortisol in plasma and urine matrices under constant routine conditions

Gunn, PJ, Middleton, B, Davies, SK, Revell, VL and Skene, DJ (2016) Sex differences in the circadian profiles of melatonin and cortisol in plasma and urine matrices under constant routine conditions CHRONOBIOLOGY INTERNATIONAL, 33 (1). pp. 39-50.

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Abstract

Conflicting evidence exists as to whether there are differences between males and females in circadian timing. The aim of the current study was to assess whether sex differences are present in the circadian regulation of melatonin and cortisol in plasma and urine matrices during a constant routine protocol. Thirty-two healthy individuals (16 females taking the oral contraceptive pill (OCP)), aged 23.8 ± 3.7 (mean ± SD) years, participated. Blood (hourly) and urine (4-hourly) samples were collected for measurement of plasma melatonin and cortisol, and urinary 6-sulfatoxymelatonin (aMT6s) and cortisol, respectively. Data from 28 individuals (14 females) showed no significant differences in the timing of plasma and urinary circadian phase markers between sexes. Females, however, exhibited significantly greater levels of plasma melatonin and cortisol than males (AUC melatonin: 937 ± 104 (mean ± SEM) vs. 642 ± 47 pg/ml.h; AUC cortisol: 13581 ± 1313 vs. 7340 ± 368 mmol/L.h). Females also exhibited a significantly higher amplitude rhythm in both hormones (melatonin: 43.8 ± 5.8 vs. 29.9 ± 2.3 pg/ml; cortisol: 241.7 ± 23.1 vs. 161.8 ± 15.9 mmol/L). Males excreted significantly more urinary cortisol than females during the CR (519.5 ± 63.8 vs. 349.2 ± 39.3 mol) but aMT6s levels did not differ between sexes. It was not possible to distinguish whether the elevated plasma melatonin and cortisol levels observed in females resulted from innate sex differences or the OCP affecting the synthetic and metabolic pathways of these hormones. The fact that the sex differences observed in total plasma concentrations for melatonin and cortisol were not reproduced in the urinary markers challenges their use as a proxy for plasma levels in circadian research, especially in OCP users.

Item Type: Article
Subjects : Biosciences
Divisions : Faculty of Health and Medical Sciences > School of Biosciences and Medicine > Department of Biochemical Sciences
Authors :
AuthorsEmailORCID
Gunn, PJUNSPECIFIEDUNSPECIFIED
Middleton, BUNSPECIFIEDUNSPECIFIED
Davies, SKUNSPECIFIEDUNSPECIFIED
Revell, VLUNSPECIFIEDUNSPECIFIED
Skene, DJUNSPECIFIEDUNSPECIFIED
Date : 2 January 2016
Identification Number : 10.3109/07420528.2015.1112396
Copyright Disclaimer : © 2016 Pippa J. Gunn, Benita Middleton, Sarah K. Davies, Victoria L. Revell, and Debra J. Skene. Published by Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords : Science & Technology, Life Sciences & Biomedicine, Biology, Physiology, Life Sciences & Biomedicine - Other Topics, melatonin, human, circadian rhythms, cortisol, constant routine, 6-sulfatoxymelatonin, Sex differences, AGE-RELATED-CHANGES, ORAL-CONTRACEPTIVES, GENDER-DIFFERENCES, SALIVARY CORTISOL, BLIND SUBJECTS, MORNINGNESS-EVENINGNESS, DIRECT RADIOIMMUNOASSAY, MENSTRUAL-CYCLE, AXIS REACTIVITY, PINEAL-GLAND
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 21 Apr 2016 12:27
Last Modified : 21 Apr 2016 12:27
URI: http://epubs.surrey.ac.uk/id/eprint/810289

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