SIRT1, AMP-activated protein kinase phosphorylation and downstream kinases in response to a single bout of sprint exercise: influence of glucose ingestion

This study was designed to examine potential in vivo mechanisms of AMP-activated protein kinase (AMPK) phosphorylation inhibition and its downstream signaling consequences during the recovery period after a single bout of sprint exercise. Sprint exercise induces Thr(172)-AMPK phosphorylation and increased PGC-1 alpha mRNA, by an unknown mechanism. Muscle biopsies were obtained in 15 young healthy men in response to a 30-s sprint exercise (Wingate test) randomly distributed into two groups: the fasting (n = 7, C) and the glucose group (n = 8, G), who ingested 75 g of glucose 1 h before exercising to inhibit AMPK alpha phosphorylation. Exercise elicited different patterns of Ser(221)-ACC beta, Ser(473)-Akt and Thr(642)-AS160 phosphorylation, during the recovery period after glucose ingestion. Thirty minutes after the control sprint, Ser(485)-AMPK alpha 1/Ser(491)-AMPK alpha 2 phosphorylation was reduced by 33% coinciding with increased Thr(172)-AMPK alpha phosphorylation (both, P < 0.05). Glucose abolished the 30-min Thr(172)-AMPK alpha phosphorylation. Ser(221)-ACC beta phosphorylation was elevated immediately following and 30 min after exercise in C and G, implying a dissociation between Thr(172)-AMPK alpha and Ser(221)-ACC beta phosphorylation. Two hours after the sprint, PGC-1 alpha protein expression remained unchanged while SIRT1 (its upstream deacetylase) was increased. Glucose ingestion abolished the SIRT1 response without any significant effect on PGC-1 alpha protein expression. In conclusion, glucose ingestion prior to a sprint exercise profoundly affects Thr(172)-AMPK alpha phosphorylation and its downstream signaling during the recovery period.