title: Muscle glycogen resynthesis, signalling and metabolic responses following acute exercise in exercise-trained pigs carrying the PRKAG3 mutation.
abstract: Hampshire pigs carrying the PRKAG3 mutation in the AMP-activated protein kinase (AMPK) γ3 subunit exhibit excessive skeletal muscle glycogen storage and an altered glycogen synthesis signalling response following exercise. AMPK plays an important role as a regulator of carbohydrate and fat metabolism in mammalian cells. Exercise-trained muscles are repeatedly exposed to glycogen degradation and resynthesis, to which the signalling pathways adapt. The aim of this study was to examine the effect of acute exercise on glycogen synthesis signalling pathways, and the levels of insulin and other substrates in blood in exercise-trained pigs with and without the PRKAG3 mutation. After 5 weeks of training, pigs performed two standardized treadmill exercise tests, and skeletal muscle biopsies were obtained immediately after exercise and 3 h postexercise in the first test, and 6 h postexercise in the second test. The PRKAG3 mutation carriers had higher glycogen storage, and resynthesis of glycogen was faster after 3 h but not after 6 h of recovery. Alterations in the concentrations of insulin, glucose, lactate and free fatty acids after exercise did not differ between the genotypes. The carriers showed a lower expression of AMPK and increased phosphorylation of Akt Ser(473) after exercise, compared with non-carriers. Acute exercise stimulated the phosphorylation of AS160 in both genotypes, and the phosphorylation of GSK3α Ser(21) and ACC Ser(79) in the non-carriers. In conclusion, exercise-trained pigs carrying the PRKAG3 mutation show an altered Akt and AMPK signalling response to acute exercise, indicating that glucose metabolism is associated with faster resynthesis of muscle glycogen in this group.
authors.affiliation: Section for Comparative Physiology and Medicine, Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, PO Box 7018, SE-750 07 Uppsala, Sweden. birgitta.essen-gustavsson@kv.slu.se
authors.forename: Birgitta
authors.initials: B
authors.lastname: Essén-Gustavsson
authors.forename: Anna
authors.initials: A
authors.lastname: Granlund
authors.forename: Boubacar
authors.initials: B
authors.lastname: Benziane
authors.forename: Marianne
authors.initials: M
authors.lastname: Jensen-Waern
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Chibalin
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005080:Exercise Test / Q000662:veterinary; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D020690:GTPase-Activating Proteins / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis; D006003:Glycogen / Q000096:biosynthesis*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D018482:Muscle, Skeletal / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013552:Swine
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; D019344:Lactic Acid; D006003:Glycogen; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; C448021:glycogen synthase kinase 3 alpha; D055372:AMP-Activated Protein Kinases