Journal Article

Allopurinol reduces oxidative stress and activates Nrf2/p62 to attenuate diabetic cardiomyopathy in rats

Luo, Jierong, Zeng, Fei, Yan, Dan, Cheung, Chi Wai, Irwin, Michael G., Liu, Shiming, Li, Sisi, Xia, Zhengyuan, Liu, Hong, Huang, Huansen

2020

Overview

Allopurinol (ALP) attenuates oxidative stress and diabetic cardiomyopathy (DCM), but the mechanism is unclear. Activation of nuclear factor erythroid 2‐related factor 2 (Nrf2) following the disassociation with its repressor Keap1 under oxidative stress can maintain inner redox homeostasis and attenuate DCM with concomitant attenuation of autophagy. We postulated that ALP treatment may activate Nrf2 to mitigate autophagy over‐activation and consequently attenuate DCM. Streptozotocin‐induced type 1 diabetic rats were untreated or treated with ALP (100 mg/kg/d) for 4 weeks and terminated after heart function measurements by echocardiography and pressure‐volume conductance system. Cardiomyocyte H9C2 cells infected with Nrf2 siRNA or not were incubated with high glucose (HG, 25 mmol/L) concomitantly with ALP treatment. Cell viability, lactate dehydrogenase, 15‐F2t‐Isoprostane and superoxide dismutase (SOD) were measured with colorimetric enzyme‐linked immunosorbent assays. ROS, apoptosis, was assessed by dihydroethidium staining and TUNEL, respectively. The Western blot and qRT‐PCR were used to assess protein and mRNA variations. Diabetic rats showed significant reductions in heart rate (HR), left ventricular eject fraction (LVEF), stroke work (SW) and cardiac output (CO), left ventricular end‐systolic volume (LVVs) as compared to non‐diabetic control and ALP improved or normalized HR, LVEF, SW, CO and LVVs in diabetic rats (all P < .05). Hearts of diabetic rats displayed excessive oxidative stress manifested as increased levels of 15‐F2t‐Isoprostane and superoxide anion production, increased apoptotic cell death and cardiomyocytes autophagy that were concomitant with reduced expressions of Nrf2, heme oxygenase‐1 (HO‐1) and Keap1. ALP reverted all the above‐mentioned diabetes‐induced biochemical changes except that it did not affect the levels of Keap1. In vitro, ALP increased Nrf2 and reduced the hyperglycaemia‐induced increases of H9C2 cardiomyocyte hypertrophy, oxidative stress, apoptosis and autophagy, and enhanced cellular viability. Nrf2 gene silence cancelled these protective effects of ALP in H9C2 cells. Activation of Nrf2 subsequent to the suppression of Keap1 and the mitigation of autophagy over‐activation may represent major mechanisms whereby ALP attenuates DCM.

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc
• Subject: Allopurinol / Allopurinol - pharmacology / Animals / Antioxidants / Apoptosis / Apoptosis - drug effects / Autophagy / Cardiomyocytes / Cardiomyopathy / Catheters / Cell activation / Cell death / Cell Line / Cell viability / Colorimetry / Conductance / Diabetes / Diabetes mellitus / Diabetes Mellitus, Experimental - complications / Diabetes Mellitus, Experimental - diagnostic imaging / Diabetes Mellitus, Experimental - pathology / Diabetes Mellitus, Experimental - physiopathology / Diabetic Cardiomyopathies - complications / Diabetic Cardiomyopathies - diagnostic imaging / Diabetic Cardiomyopathies - pathology / Diabetic Cardiomyopathies - physiopathology / diabetic cardiomyopathy / Diastole - drug effects / Drinking water / Echocardiography / Ejection fraction / Enzymes / Experiments / Glucose / Glucose - toxicity / Heart rate / Heart Ventricles - diagnostic imaging / Heart Ventricles - drug effects / Heart Ventricles - pathology / Heart Ventricles - physiopathology / Heme / Hemodynamics - drug effects / Homeostasis / Hyperglycemia / Hyperglycemia - complications / Hyperglycemia - pathology / Hyperglycemia - physiopathology / Hypertrophy / Insulin / International organizations / Kelch-Like ECH-Associated Protein 1 - metabolism / L-Lactate dehydrogenase / Lactic acid / Male / Models, Biological / mRNA / Myocytes, Cardiac - drug effects / Myocytes, Cardiac - metabolism / Myocytes, Cardiac - pathology / NF-E2-Related Factor 2 - metabolism / Nrf2 / NRF2 protein / Original / Oxidative stress / Oxidative Stress - drug effects / Oxygenase / Phagocytosis / Plasma / Proteins / Rats, Sprague-Dawley / Rodents / Sequestosome-1 Protein - metabolism / Signal Transduction - drug effects / siRNA / Stroke / Studies / Superoxide dismutase / Systole - drug effects / Transcription factors / Ventricle