Acylated Ghrelin Concentrations are Suppressed During Aerobic Exercise

Abstract

Ghrelin is an orexigenic (appetite stimulating) hormone secreted primarily from endocrine cells in the stomach. Studies have shown that total plasma ghrelin concentrations are unaffected by a single session of exercise. However, the majority of ghrelin in plasma is inactive (non-acylated). Acylation of ghrelin is required for it to exert an appetite stimulating effect. PURPOSE: To assess the effect of a single bout of treadmill running on plasma acylated ghrelin concentration. METHODS: Nine healthy males (age 21.2 ± 2.1 y, body mass 72.6 ± 6.7 kg, BMI 22.2 ± 2.4 kg·m−2, body fat 14.2 ± 3.5 %, maximum oxygen uptake 63.3 ± 7.0 mL·kg−1min−1, mean ± SD) participated in two, 9-h trials (exercise and control) in a random crossover design. Both trials began in the morning after an overnight fast. On the exercise trial participants ran for 60 min at 72 ± 6 % of maximum oxygen uptake. After this they rested for 8 h and consumed a test meal at 3 h (i.e. two hours after exercise). On the control trial participants rested for 9 h and at 3 h they consumed an identical test meal to that consumed on the exercise trial. Venous blood samples were taken at 0, 0.5, 1, 3, 4 and 9 h for the determination of plasma acylated ghrelin concentration using an enzyme immunoassay (SPI-BIO supplied by IDS Ltd). Hunger ratings were recorded using a visual scale. RESULTS: Plasma acylated ghrelin concentration (Table) was suppressed during and following the run on the exercise trial and after feeding on both trials i.e. at 4 h (two-way ANOVA, main effect of trial P <0.03, main effect of time P <0.05, trial x time interaction P <0.05). Subjective ratings of hunger declined during the run on the exercise trial and after feeding on both trials (two-way ANOVA, main effect of trial P = 0.19, main effect of time P <0.0005, trial x time interaction P <0.001).Table: Plasma acylated ghrelin concentrations (pg·mL−1) during control and exercise trials: median (range).CONCLUSIONS: These findings suggest that an intense bout of treadmill running suppresses appetite. This suppression is associated with a decline in plasma acylated ghrelin concentration.