Journal
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
Volume 290, Issue 6, Pages E1296-E1303Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpendo.00341.2005
Keywords
insulin sensitivity; adenosine 5 '-monophosphate kinase; acetyl-coenzyme A carboxylase; peroxisome proliferator-activated receptor-gamma coactivator-1 alpha
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Funding
- NIAMS NIH HHS [AR-45670, AR-42238] Funding Source: Medline
- NIDDK NIH HHS [DK-19514, DK-62948, DK-49147] Funding Source: Medline
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The study was designed to evaluate whether changes in malonyl-CoA and the enzymes that govern its concentration occur in human muscle as a result of physical training. Healthy, middle-aged subjects were studied before and after a 12-wk training program that significantly increased Vo(2) (max) by 13% and decreased intra-abdominal fat by 17%. Significant decreases (25-30%) in the concentration of malonyl-CoA were observed after training, 24-36 h after the last bout of exercise. They were accompanied by increases in both the activity (88%) and mRNA (51%) of malonyl-CoA decarboxylase (MCD) in muscle but no changes in the phosphorylation of AMP kinase (AMPK, Thr172) or of acetyl-CoA carboxylase. The abundance of peroxisome proliferator-activated receptor (PPAR)gamma coactivator-1 alpha (PGC-1 alpha), a regulator of transcription that has been linked to the mediation of MCD expression by PPAR gamma, was also increased ( 3- fold). In studies also conducted 24 - 36 h after the last bout of exercise, no evidence of increased whole body insulin sensitivity or fatty acid oxidation was observed during an euglycemic hyperinsulinemic clamp. In conclusion, the concentration of malonylCoA is diminished in muscle after physical training, most likely because of PGC- 1 alpha- mediated increases in MCD expression and activity. These changes persist after the increases in AMPK activity and whole body insulin sensitivity and fatty acid oxidation, typically caused by an acute bout of exercise in healthy individuals, have dissipated.
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