Long-term exercise stimulates adenosine monophosphate–activated protein kinase activity and subunit expression in rat visceral adipose tissue and liver

• Published in: Metabolism, clinical and experimental Vol. 55; no. 8; pp. 1122 - 1128
• Main Authors: Takekoshi, Kazuhiro, Fukuhara, Michiko, Quin, Zeng, Nissato, Sumiko, Isobe, Kazumasa, Kawakami, Yasushi, Ohmori, Hajime
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.08.2006; Elsevier
• Subjects: Adipose Tissue - enzymology; AMP-Activated Protein Kinases; Animals; Biological and medical sciences; Blood Glucose - metabolism; Blotting, Western; Body Weight - physiology; Cholesterol - blood; Cholesterol, HDL - blood; Liver - enzymology; Male; Medical sciences; Metabolic diseases; Multienzyme Complexes - biosynthesis; Multienzyme Complexes - metabolism; Oxygen Consumption - physiology; Physical Conditioning, Animal - physiology; Protein-Serine-Threonine Kinases - biosynthesis; Protein-Serine-Threonine Kinases - metabolism; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - biosynthesis; RNA, Messenger - genetics; Triglycerides - blood; Physical exercise; Adipose tissue; Rat; Digestive system; Enzyme; Transferases; Liver; Rodentia; Activity; Gene expression; Subunit; Long term; Vertebrata; Mammalia; Adenosine kinase; Protein kinase; Animal
• ISSN: 0026-0495; 1532-8600
• DOI: 10.1016/j.metabol.2006.04.007

Adenosine monophosphate–activated protein kinase (AMPK) is activated in response to adenosine triphosphate depletion caused by the metabolic and nutritional state. Mammalian AMPK is a heterotrimeric enzyme composed of a catalytic α subunit and 2 regulatory subunits ( β and γ). Although much attention has been focused on exercise-induced AMPK activation in skeletal muscle, little information is available on the role of AMPK in adipose tissue and liver. Acetyl-coenzyme A carboxylase (ACC) is a well-known downstream target of AMPK. The ACC contains serine residues that are phosphorylated by AMPK. The present study was undertaken to determine whether long-term exercise of medium intensity (60% of V˙ o 2max for 12 weeks) may influence AMPK enzyme activity, gene/protein expression, and subsequent ACC phosphorylation in rat adipose tissue (visceral and subcutaneous) and liver. We initially demonstrated that long-term exercise induced a significant increase in phosphorylation of Thr 172 in the AMPK α 1 subunit and of Ser 79 in ACC in visceral adipose tissue rather than subcutaneous tissue. We also demonstrated that the AMPK α 1-, α 2-subunit messenger RNA (mRNA) level as well as the corresponding protein levels were increased in response to long-term exercise, whereas the other subunits were not altered significantly. In contrast to that of visceral adipose tissue, long-term exercise did not induce any significant effect on any of the AMPK subunit mRNA levels or α 1-, α 2-subunit protein levels in subcutaneous adipose tissue. In addition to adipose tissue, we demonstrated that long-term exercise induced an increase in both AMPK/ACC phosphorylation and α 1-, α 2-subunit mRNA/protein expression in the liver. Although the precise physiologic relevance of AMPK activation in these tissues remains unknown, it is possible that it might play an important role in long-term exercise-induced adaptation mechanisms and may lead to an improvement in certain metabolic abnormalities in metabolic diseases.