title: Glucose variability aggravates cardiac fibrosis by altering AKT signalling path.
abstract: To study the effect of blood glucose variability on cardiac fibrosis and its mechanism in a model of diabetic cardiomyopathy.
  
  
  
  A total of 45 Sprague Dawley rats were randomly divided into three groups: control, control diabetes mellitus and fluctuated blood glucose groups. Fluctuated blood glucose was induced by daily subcutaneous insulin and intraperitoneal glucose injections at different time points. Blood lipids and glycosylated haemoglobin A1c were assessed. Super oxide dismutase activity and malondialdehyde level in rat heart homogenates were determined by assay kit. Structural cardiac tissue changes were observed by haematoxylin and eosin staining and Masson's trichrome staining. Collagen type 3, fibronectin, phosphorylated Ser/Thr protein kinase, phosphorylated glycogen synthase kinase-3 beta, glycogen synthase kinase-3 beta, nuclear factor kappa-light-chain-enhancer of activated B cells, cleaved-cysteinyl aspartate-specific proteinase-3 (caspase-3) and tumour necrosis factor-α levels were determined by western blot.
  
  
  
  Compared with the control group, cardiac fibrosis and oxidative stress in heart tissue were aggravated in diabetic rats, which were more pronounced in glucose variability rats. However, the expression levels of AKT and glycogen synthase kinase-3 beta were not significantly different in three groups, but the expression levels of phosphorylated Ser/Thr protein kinase and phosphorylated glycogen synthase kinase-3 beta were significantly decreased in the control diabetes mellitus and fluctuated blood glucose groups compared to control group, and levels in the fluctuated blood glucose group were significantly less than in the control diabetes mellitus group. In addition, the expression levels of nuclear factor kappa B and caspase-3 in both the control diabetes mellitus and fluctuated blood glucose groups were higher than in the control group, with the highest levels measured in the fluctuated blood glucose group.
  
  
  
  Blood glucose variability can aggravate heart tissue fibrosis, possibly involving oxidative stress by inhibiting AKT signalling path.
authors.affiliation: 1 Department of Endocrinology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Changjiang
authors.initials: C
authors.lastname: Ying
authors.affiliation: 2 The Graduate School, Xuzhou Medical University, Xuzhou, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Liu
authors.affiliation: 1 Department of Endocrinology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Ling
authors.affiliation: 3 Department of Cardiology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Cheng
authors.affiliation: 4 Laboratory of Morphology, Xuzhou Medical University, Xuzhou, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhou
authors.affiliation: 2 The Graduate School, Xuzhou Medical University, Xuzhou, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Wang
authors.affiliation: 2 The Graduate School, Xuzhou Medical University, Xuzhou, China.
authors.forename: Yizhen
authors.initials: Y
authors.lastname: Mao
authors.affiliation: 2 The Graduate School, Xuzhou Medical University, Xuzhou, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: 5 Xuzhou Medical University, Xuzhou, China.
authors.forename: Runze
authors.initials: R
authors.lastname: Zhang
authors.affiliation: 1 Department of Endocrinology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood* / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications; D058065:Diabetic Cardiomyopathies / Q000097:blood / Q000201:enzymology / Q000209:etiology* / Q000473:pathology; D005355:Fibrosis; D006442:Glycated Hemoglobin / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism; D008055:Lipids / Q000097:blood; D008297:Male; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D053148:Caspase 3; D006442:Glycated Hemoglobin; D000071679:Glycogen Synthase Kinase 3 beta; D008055:Lipids; D016328:NF-kappa B; D051057:Proto-Oncogene Proteins c-akt; D014409:Tumor Necrosis Factor-alpha; C000605508:Gsk3b protein, rat; C505410:Casp3 protein, rat
keywords: AKT; Blood glucose variability; diabetic cardiomyopathy; oxidative stress