title: Development of insulin resistance and obesity in mice overexpressing cellular glutathione peroxidase.
abstract: Insulin resistance, a hallmark of type 2 diabetes, is associated with oxidative stress. However, the role of reactive oxygen species or specific antioxidant enzymes in its development has not been tested under physiological conditions. The objective of our study was to investigate the impact of overexpression of glutathione peroxidase 1 (GPX1), an intracellular selenoprotein that reduces hydrogen peroxide (H(2)O(2)) in vivo, on glucose metabolism and insulin function. The GPX1-overexpressing (OE) and WT male mice (n = 80) were fed a selenium-adequate diet (0.4 mg/kg) from 8 to 24 weeks of age. Compared with the WT, the OE mice developed (P < 0.05) hyperglycemia (117 vs. 149 mg/dl), hyperinsulinemia (419 vs. 1,350 pg/ml), and elevated plasma leptin (5 vs. 16 ng/ml) at 24 weeks of age. Meanwhile, these mice were heavier (37 vs. 27 g, P < 0.001) and fatter (37% vs. 17% fat, P < 0.01) than the WT mice. At 30-60 min after an insulin challenge, the OE mice had 25% less (P < 0.05) of a decrease in blood glucose than the WT mice. Their insulin resistance was associated with a 30-70% reduction (P < 0.05) in the insulin-stimulated phosphorylations of insulin receptor (beta-subunit) in liver and Akt (Ser(473) and Thr(308)) in liver and soleus muscle. Here we report the development of insulin resistance in mammals with elevated expression of an antioxidant enzyme and suggest that increased GPX1 activity may interfere with insulin function by overquenching intracellular reactive oxygen species required for insulin sensitizing.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: James P
authors.initials: JP
authors.lastname: McClung
authors.forename: Carol A
authors.initials: CA
authors.lastname: Roneker
authors.forename: Weipeng
authors.initials: W
authors.lastname: Mu
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Lisk
authors.forename: Paul
authors.initials: P
authors.lastname: Langlais
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Xin Gen
authors.initials: XG
authors.lastname: Lei
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D005979:Glutathione Peroxidase / Q000096:biosynthesis / Q000097:blood / Q000378:metabolism*; D005982:Glutathione Transferase / Q000097:blood / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D020738:Leptin / Q000097:blood; D008099:Liver / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D009132:Muscles / Q000201:enzymology; D009765:Obesity / Q000201:enzymology* / Q000378:metabolism; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin / Q000378:metabolism; D012643:Selenium / Q000378:metabolism; D013482:Superoxide Dismutase / Q000097:blood / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000097:blood / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D011518:Proto-Oncogene Proteins; D000080662:Phospholipid Hydroperoxide Glutathione Peroxidase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D013880:Thioredoxin-Disulfide Reductase; D005982:Glutathione Transferase; D011972:Receptor, Insulin; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D012643:Selenium