title: Insulin stimulates glucose uptake via a phosphatidylinositide 3-kinase-linked signaling pathway in bovine mammary epithelial cells.
abstract: The aim of this study was to investigate the effects of insulin on glucose uptake in lactating bovine mammary epithelial cells (BMEC). Primary BMEC were cultured in Dulbecco's modified Eagle's medium/nutrient mixture F-12 and treated with different levels of insulin (0, 5, 50, and 500 ng/mL) for 48 h after a 24-h starvation without fetal calf serum. Compared with the control cells (0 ng of insulin/mL), cell proliferation was enhanced by insulin treatment at all tested levels. Insulin significantly increased glucose uptake at a concentration of 500 ng/mL. In addition, the protein synthesis inhibitor cycloheximide (0.5mg/mL) counteracted the insulin-elevated glucose uptake, thereby suggesting that newly synthesized transporter protein might take part in the insulin-induced glucose uptake. Furthermore, pretreatment of the cells with SB203580, an inhibitor of p38 mitogen-activated protein kinase, did not influence the insulin-induced glucose uptake, but LY294002, a specific inhibitor of phosphatidylinositide 3-kinase, significantly reduced the insulin-stimulated glucose uptake. These results indicated that insulin-induced glucose uptake in BMEC may involve the phosphatidylinositide 3-kinase- but not mitogen-activated protein kinase-mediated signaling pathways.
authors.affiliation: Institute of Dairy Science, MOE Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou 310058, P. R. China; Shaanxi Institute of Zoology, 88 Xingqing Road, Xi'an 710032, P. R. China.
authors.forename: K
authors.initials: K
authors.lastname: Zhao
authors.affiliation: Institute of Dairy Science, MOE Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou 310058, P. R. China. Electronic address: hyliu@zju.edu.cn.
authors.forename: H-Y
authors.initials: HY
authors.lastname: Liu
authors.affiliation: Institute of Dairy Science, MOE Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou 310058, P. R. China.
authors.forename: M-M
authors.initials: MM
authors.lastname: Zhou
authors.affiliation: Institute of Dairy Science, MOE Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou 310058, P. R. China; Laboratory of Lactation and Metabolic Physiology, Department of Animal Science, University of Vermont, Burlington 05405.
authors.forename: F-Q
authors.initials: FQ
authors.lastname: Zhao
authors.affiliation: Institute of Dairy Science, MOE Key Laboratory of Molecular Animal Nutrition, Zhejiang University, Hangzhou 310058, P. R. China. Electronic address: liujx@zju.edu.cn.
authors.forename: J-X
authors.initials: JX
authors.lastname: Liu
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism*; D007774:Lactation; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002867:Chromones; D004791:Enzyme Inhibitors; D005947:Glucose; D007093:Imidazoles; D007328:Insulin; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; D048051:p38 Mitogen-Activated Protein Kinases; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093642:SB 203580
keywords: bovine; glucose transporter 8 (GLUT8); glucose uptake; insulin; mammary epithelial cell