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Type: Journal article
Title: Overfeeding reduces insulin sensitivity and increases oxidative stress, without altering markers of mitochondrial content and function in humans
Author: Samocha-Bonet, D.
Campbell, L.
Mori, T.
Croft, K.
Greenfield, J.
Turner, N.
Heilbronn, L.
Citation: PLoS One, 2012; 7(5):1-8
Publisher: Public Library of Science
Issue Date: 2012
ISSN: 1932-6203
Statement of
Dorit Samocha-Bonet, Lesley V. Campbell, Trevor A. Mori, Kevin D. Croft, Jerry R. Greenfield, Nigel Turner and Leonie K. Heilbronn
Abstract: BACKGROUND: Mitochondrial dysfunction and increased oxidative stress are associated with obesity and type 2 diabetes. High fat feeding induces insulin resistance and increases skeletal muscle oxidative stress in rodents, but there is controversy as to whether skeletal muscle mitochondrial biogenesis and function is altered. METHODOLOGY AND PRINCIPAL FINDINGS: Forty (37±2 y) non-obese (25.6±0.6 kg/m2) sedentary men (n = 20) and women (n = 20) were overfed (+1040±100 kcal/day, 46±1% of energy from fat) for 28 days. Hyperinsulinemic-euglycemic clamps were performed at baseline and day 28 of overfeeding and skeletal muscle biopsies taken at baseline, day 3 and day 28 of overfeeding in a sub cohort of 26 individuals (13 men and 13 women) that consented to having all 3 biopsies performed. Weight increased on average in the whole cohort by 0.6±0.1 and 2.7±0.3 kg at days 3 and 28, respectively (P<0.0001, without a significant difference in the response between men and women (P = 0.4). Glucose infusion rate during the hyperinsulinemic-euglycemic clamp decreased from 54.8±2.8 at baseline to 50.3±2.5 mmol/min/kg FFM at day 28 of overfeeding (P = 0.03) without a significant difference between men and women (P = 0.4). Skeletal muscle protein carbonyls and urinary F2-isoprostanes increased with overfeeding (P,<.05). Protein levels of muscle peroxisome proliferator-activated receptor gamma coactivator-1a (PGC1a) and subunits from complex I, II and V of the electron transport chain were increased at day 3 (all P<0.05) and returned to basal levels at day 28. No changes were detected in muscle citrate synthase activity or ex vivo CO2 production at either time point. CONCLUSIONS: Peripheral insulin resistance was induced by overfeeding, without reducing any of the markers of mitochondrial content that were examined. Oxidative stress was however increased, and may have contributed to the reduction in insulin sensitivity observed.
Keywords: Muscle, Skeletal; Mitochondria; Humans; Diabetes Mellitus, Type 2; Insulin Resistance; Obesity; Body Weight; Weight Gain; Insulin; Citrate (si)-Synthase; Blood Glucose; Intracellular Signaling Peptides and Proteins; Biopsy; Cohort Studies; Oxidative Stress; Adult; Female; Male; Lipid Metabolism; Diet, High-Fat
Rights: Copyright: © 2012 Samocha-Bonet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
RMID: 0020118973
DOI: 10.1371/journal.pone.0036320
Appears in Collections:Medicine publications

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