Daily profile in two circadian markers "melatonin and cortisol" and associations with metabolic syndrome components

Objective: The aim of the present work was to investigate associations in circadian markers, melatonin (MT) and cortisol, with metabolic syndrome (MetS) parameters, and with leptin, adiponectin and ghrelin plasma values. Methods: The study was conducted in 70 women (mean age: 41 +/- 10 years) that were classified without MetS (n = 30) and with MetS (n = 40). Blood collection, plasma separation and processing, and biochemical analyses for plasma lipids were performed. For measuring salivary melatonin, participants collected two samples. The first simple was obtained before lunch (at 14:00 p.m.) and the second sample was taken at night (3:00 a.m.). On a random working day, participants delivered repeated salivary cortisol samples. The first sample was obtained in the morning (09:00 a.m.), then before lunch at (14:00 p.m.), and finally just before bedtime (23:00 p.m.). Results: Significant differences were found between the MT measurements taken at night in women without and with MetS. With respect to cortisol, significant differences were found in the different times cortisol levels toward a more flattened pattern among MetS women. Both parameters were positive correlated between them. Of note MT and cortisol night/morning ratios were associated with MetS score and metabolic syndrome components. Conclusion: The findings indicate that diminished daily amplitude in MT and cortisol circadian patterns was associated with metabolic disturbances in blood pressure, glucose and plasma lipids regulation, ghrelin and adipocyte-secreted hormones such as leptin and adiponectin. (C) 2012 Elsevier Inc. All rights reserved.