title: Hyperglycemia induced by glucose infusion causes hepatic oxidative stress and systemic inflammation, but not STAT3 or MAP kinase activation in liver in rats.
abstract: The purpose of this study was to determine the effects of acute hyperglycemia induced by glucose infusion on oxidative stress, systemic inflammation, and several key signal intermediates in liver for the systemic inflammatory response in nonstressed rats. Rats received saline or glucose infusion (hyperglycemic clamp) for 3 hours. Rats without catheter insertion were included as an additional control for observing the effects of surgical stress. Levels of malondialdehyde (MDA) and total glutathione to assess oxidative stress were determined in liver and muscle. Proinflammatory cytokines including tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6, and alpha 1 acid glycoprotein (alpha1-AG) were determined in serum. The protein content and phosphorylation of extracellular signal-regulated kinase (ERK)1/2, p38 stress-activated protein kinase (p38), and signal transducer and activator of transcription-3 (STAT-3) were examined in the liver tissue with or without IL-6 stimulation. The results showed that acute hyperglycemia significantly increased MDA release and depleted total glutathione in liver but not in muscle. Hyperglycemia also significantly elevated the production of TNF, IL-1, and alpha1-AG, but not IL-6 in serum. However, hyperglycemia for 3 hours in vivo did not activate ERK1/2, p38 and STAT3 in liver, and also did not alter the response of these signal proteins to IL-6 stimulation. These data suggest that acute (3 hours) hyperglycemia causes hepatic oxidative stress and activates a low-grade systemic inflammation but does not affect key components of the IL-6 signaling pathway in liver.
authors.affiliation: Nutrition/Infection Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Pei-Ra
authors.initials: PR
authors.lastname: Ling
authors.forename: Claudia
authors.initials: C
authors.lastname: Mueller
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Smith
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Bistrian
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005947:Glucose / Q000008:administration & dosage; D015309:Glucose Clamp Technique; D005978:Glutathione / Q000032:analysis; D006943:Hyperglycemia / Q000139:chemically induced / Q000150:complications / Q000378:metabolism*; D007249:Inflammation / Q000209:etiology*; D007328:Insulin / Q000097:blood; D007375:Interleukin-1 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000737:chemistry; D009961:Orosomucoid / Q000032:analysis; D018384:Oxidative Stress; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D050796:STAT3 Transcription Factor; D013312:Stress, Physiological / Q000209:etiology / Q000378:metabolism; D013514:Surgical Procedures, Operative; D015534:Trans-Activators / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D001786:Blood Glucose; D004268:DNA-Binding Proteins; D007328:Insulin; D007375:Interleukin-1; D015850:Interleukin-6; D009961:Orosomucoid; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D008315:Malondialdehyde; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D005978:Glutathione; D005947:Glucose