Oxidative stress-dependent impairment of cardiac-specific transcription factors in experimental diabetes.
Oxidative stress plays a key role in the pathogenesis of diabetic cardiomyopathy, which is characterized by myocyte loss and fibrosis, finally resulting in heart failure. The study looked at the downstream signaling whereby oxidative stress leads to reduced myocardial contractility in the left ventricle of diabetic rats and the effects of dehydroepiandrosterone (DHEA), which production is suppressed in the failing heart and prevents the oxidative damage induced by hyperglycemia in several experimental models. DHEA was given orally at a dose of 4 mg/rat per day for 21 d to rats with streptozotocin (STZ)-induced diabetes and genetic diabetic-fatty (ZDF) rats. Oxidative balance, advanced glycated end products (AGEs) and AGE receptors, cardiac myogenic factors, and myosin heavy-chain gene expression were determined in the left ventricle of treated and untreated STZ-diabetic rats and ZDF rats. Oxidative stress induced by chronic hyperglycemia increased AGE and AGE receptors and led to activation of the pleoitropic transcription factor nuclear factor-kappaB. Nuclear factor-kappaB activation triggered a cascade of signaling, which finally led to the switch in the cardiac myosin heavy-chain (MHC) gene expression from the alpha-MHC isoform to the beta-MHC isoform. DHEA treatment, by preventing the activation of the oxidative pathways induced by hyperglycemia, counteracted the enhanced AGE receptor activation in the heart of STZ-diabetic rats and ZDF rats and normalized downstream signaling, thus avoiding impairment of the cardiac myogenic factors, heart autonomic nervous system and neural crest derivatives (HAND) and myogenic enhancer factor-2, and the switch in MHC gene expression, which are the early events in diabetic cardiomyopathy.
Aragno
Manuela
M
Department of Experimental Medicine and Oncology, General Pathology Section, University of Turin, 10126 Turin, Italy.
Mastrocola
Raffaella
R
Medana
Claudio
C
Catalano
Maria Graziella
MG
Vercellinatto
Ilenia
I
Danni
Oliviero
O
Boccuzzi
Giuseppe
G
D000818:Animals; D003687:Dehydroepiandrosterone / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism* / Q000473:pathology; D017127:Glycation End Products, Advanced / Q000097:blood; D006321:Heart / Q000187:drug effects; D006352:Heart Ventricles / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D018995:Myosin Heavy Chains / Q000378:metabolism; D009928:Organ Specificity; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011924:Rats, Zucker; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000032:analysis; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D014157:Transcription Factors / Q000032:analysis* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D017127:Glycation End Products, Advanced; C000594638:MYH7 protein, rat; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D047888:Receptors, Tumor Necrosis Factor, Type I; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D003687:Dehydroepiandrosterone; D018995:Myosin Heavy Chains