Lack of Day/Night variation in fibroblast growth factor 21 levels in young healthy men

• Published in: International Journal of Obesity 2015-06, Vol.39 (6), p.945-948
• Main Authors: Foo, J-P, Aronis, K N, Chamberland, J P, Mantzoros, C S
• Format: Article
• Language: English
• Subjects: 13/21; 13/56; 14/1; 631/443/319; 631/80/105; 692/163; 692/308; Analysis; Biological rhythms; Body mass index; Circadian Rhythm - physiology; Circadian rhythms; Diabetes; Dimorphism (Biology); Embryos; Endocrinology; Energy; Energy Metabolism - physiology; Epidemiology; Fatty acids; Fatty Acids, Nonesterified - blood; Female; Fibroblast growth factors; Fibroblast Growth Factors - blood; Fibroblasts; Gender; Glucose; Growth factors; Health aspects; Health care; Health Promotion and Disease Prevention; Healthy Volunteers; Homeostasis; Humans; Internal Medicine; Leptin - blood; Lipid metabolism; Lipids; Male; Medicine; Medicine & Public Health; Metabolic Diseases; Metabolic regulation; Metabolism; Night; Obesity; original-article; Physiological aspects; Physiology; Public Health; Sex Characteristics; Sexual dimorphism; Signal Transduction; Statistical analysis; Statistical methods; Triglycerides; Variation; Weight Loss; Young Adult; Young men
• ISSN: 0307-0565; 1476-5497
• DOI: 10.1038/ijo.2014.215

Background: Fibroblast growth factor (FGF) 21 is an endocrine factor with an emerging role as a metabolic regulator. We previously reported the presence of a significant day/night variation of FGF-21 in energy-replete, healthy female subjects. However the day/night patterns of secretion in male subjects remain to be fully elucidated. To elucidate day/night pattern of FGF-21 levels in male subjects in the energy-replete state, its relationship to FFA and to investigate whether a sexual dimorphism exists in FGF-21 physiology. Methods: Eight healthy lean male subjects were studied for up to 5 days while on an isocaloric diet. Blood samples were obtained for measurement of FGF-21 and free fatty acids (FFA) hourly from 0800 AM on day 4 till 0800AM on day 5. Results: FGF-21 did not exhibit any statistically significant day/night variation pattern of circulating FGF-21 levels during the isocaloric fed state in male subjects. FGF-21 levels in male subjects are closely cross-correlated with FFA levels, similar to female subjects. Conclusions: A sexual dimorphism exists in FGF-21 physiology; that as opposed to female subjects, no significant day/night variation exists in FGF-21 rhythm in male subjects in the energy-replete state. Circulating pattern of FGF-21, similar to the female subjects, was highly cross-correlated to the FFA levels in the male subjects, signifying that the sexual dimorphism in FGF-21 physiology may be related to the differing lipid metabolism in both the genders.