CONTEXT: Follistatin inhibits TGF-β superfamily ligands, is involved in muscle atrophy, and is elevated in several endocrine disorders and in response to exercise or fasting. Follistatin is expressed in various tissues with the liver as a major contributor to the circulating levels. Current evidence shows contradictory results on whether circulating levels of follistatin displays a circadian rhythm.
OBJECTIVE: To characterize the 24-hour temporal pattern of plasma follistatin in healthy young men.
DESIGN: Observational 24-hour study with blood sampling every three hours. Cosinor rhythmometry and one-way repeated measures ANOVA were used to analyze plasma follistatin.
SETTING: Controlled research facility simulating normal daily life.
PATIENTS OR OTHER PARTICIPANTS: Twenty-two healthy young men were included in this study.
INTERVENTION(S): No interventions were applied.
MAIN OUTCOME MEASURE(S): Plasma concentrations of follistatin. This was measured in order to investigate the temporal pattern of follistatin to gain insight into its physiological actions and regulation.
RESULTS: Plasma follistatin showed a significant 24-hour rhythm (p<0.001) with a relative amplitude of 18% around a rhythm adjusted average (mesor±SD) of 873 ± 25 pg/mL, peaking at 11:50 h. ANOVA confirmed a significant effect of time, with morning and evening levels differing significantly.
CONCLUSIONS: Plasma follistatin displayed a significant 24-hour rhythm in our cohort of 22 healthy young men. While meal intake, particularly protein, influences follistatin, it does not fully explain the observed rhythm. Further studies are needed to confirm this rhythm and clarify its clinical relevance.
