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-1α 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 AMPKα phosphorylation. Exercise elicited different patterns of Ser 221 -ACCβ, Ser 473 -Akt and Thr 642 -AS160 phosphorylation, during the recovery period after glucose ingestion. Thirty minutes after the control sprint, Ser 485 -AMPKα1/Ser 491 -AMPKα2 phosphorylation was reduced by 33% coinciding with increased Thr 172 -AMPKα phosphorylation (both, P < 0.05). Glucose abolished the 30-min Thr 172 -AMPKα phosphorylation. Ser 221 -ACCβ phosphorylation was elevated immediately following and 30 min after exercise in C and G, implying a dissociation between Thr 172 -AMPKα and Ser 221 -ACCβ phosphorylation. Two hours after the sprint, PGC-1α protein expression remained unchanged while SIRT1 (its upstream deacetylase) was increased. Glucose ingestion abolished the SIRT1 response without any significant effect on PGC-1α protein expression. In conclusion, glucose ingestion prior to a sprint exercise profoundly affects Thr 172 -AMPKα phosphorylation and its downstream signaling during the recovery period.