title: Exercise training enhances white adipose tissue metabolism in rats selectively bred for low- or high-endurance running capacity.
abstract: Impaired visceral white adipose tissue (WAT) metabolism has been implicated in the pathogenesis of several lifestyle-related disease states, with diminished expression of several WAT mitochondrial genes reported in both insulin-resistant humans and rodents. We have used rat models selectively bred for low- (LCR) or high-intrinsic running capacity (HCR) that present simultaneously with divergent metabolic phenotypes to test the hypothesis that oxidative enzyme expression is reduced in epididymal WAT from LCR animals. Based on this assumption, we further hypothesized that short-term exercise training (6 wk of treadmill running) would ameliorate this deficit. Approximately 22-wk-old rats (generation 22) were studied. In untrained rats, the abundance of mitochondrial respiratory complexes I-V, citrate synthase (CS), and PGC-1 was similar for both phenotypes, although CS activity was greater than 50% in HCR (P = 0.09). Exercise training increased CS activity in both phenotypes but did not alter mitochondrial protein content. Training increased the expression and phosphorylation of proteins with roles in β-adrenergic signaling, including β3-adrenergic receptor (16% increase in LCR; P < 0.05), NOR1 (24% decrease in LCR, 21% decrease in HCR; P < 0.05), phospho-ATGL (25% increase in HCR; P < 0.05), perilipin (25% increase in HCR; P < 0.05), CGI-58 (15% increase in LCR; P < 0.05), and GLUT4 (16% increase in HCR; P < 0.0001). A training effect was also observed for phospho-p38 MAPK (12% decrease in LCR, 20% decrease in HCR; P < 0.05) and phospho-JNK (29% increase in LCR, 20% increase in HCR; P < 0.05). We conclude that in the LCR-HCR model system, mitochondrial protein expression in WAT is not affected by intrinsic running capacity or exercise training. However, training does induce alterations in the activity and expression of several proteins that are essential to the intracellular regulation of WAT metabolism.
authors.affiliation: School of Medical Sciences, Royal Melbourne Institute of Technology, Bundoora, Australia.
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Stephenson
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Lessard
authors.forename: Donato A
authors.initials: DA
authors.lastname: Rivas
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Watt
authors.forename: Ben B
authors.initials: BB
authors.lastname: Yaspelkis
authors.forename: Lauren G
authors.initials: LG
authors.lastname: Koch
authors.forename: Steven L
authors.initials: SL
authors.lastname: Britton
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
mesh_terms: D052436:Adipose Tissue, White / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D001835:Body Weight / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis / Q000235:genetics; D008066:Lipolysis / Q000502:physiology; D008297:Male; D024101:Mitochondrial Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000096:biosynthesis / Q000235:genetics; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000235:genetics* / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D012420:Running / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D051275:Glucose Transporter Type 4; D024101:Mitochondrial Proteins; D009419:Nerve Tissue Proteins; C539820:Nr4a1 protein, rat; C091333:Nr4a3 protein, rat; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D016601:RNA-Binding Proteins; C495694:Slc2a4 protein, rat; D014157:Transcription Factors; D002950:Citrate (si)-Synthase; D011494:Protein Kinases
keywords: exercise; lipolysis; metabolism; mitochondria; white adipose tissue