Effects of endurance running and dietary fat on circulating ghrelin and peptide YY

ghrelin and peptide yy (pyy) are newly recognized gutpeptides involved in appetite regulation. plasma ghrelinconcentrations are elevated in fasting and suppressed followinga meal, while pyy concentrations are suppressed in fasting andelevated postprandially. we determine whether ghrelin and pyyare altered by a low-fat, high-carbohydrate (10% fat, 75%carbohydrate) or moderate-fat, moderate-carbohydrate (35% fat,50% carbohydrate) diet and; whether these peptides are affectedby intense endurance running (which is likely to temporarilysuppress appetite). twenty-one endurance-trained runnersfollowed a controlled diet (25% fat) and training regimen for 3days before consuming the low-fat or isoenergetic moderate-fatdiet for another 3 days in random cross-over fashion. on day 7runners underwent glycogen restoration and then completed a90-minute pre-loaded 10-km time trial on day 8, following acontrol breakfast. blood samples were obtained on days 4 and 7(fasting), and day 8 (non-fasting) before and after exercise foranalysis of ghrelin, pyy, insulin and growth hormone (gh).insulin, gh, ghrelin and pyy changed significantly over time(p < 0.0001) but were not influenced by diet. ghrelin waselevated during fasting (days 4 and 7), while insulin and pyywere suppressed. following the pre-exercise meal, ghrelin wassuppressed ~17% and insulin and pyy were elevated ~157 and~40%, respectively, relative to fasting (day 7). followingexercise, pyy, ghrelin, and gh were significantly (p < 0.0001)increased by ~11, ~16 and ~813%, respectively. the noteddisruption in the typical inverse relationship between ghrelinand pyy following exercise suggests that interaction of thesepeptides may be at least partially responsible for post-exerciseappetite suppression. these peptides do not appear to beinfluenced by dietary fat intake.