Alterations in Energy Metabolism, Mitochondrial Function and Redox Homeostasis in GK Diabetic Rat Tissues Treated with Aspirin

Abstract

Our recent studies have demonstrated that aspirin treatment prevents inflammatory and oxidative stress-induced alterations in mitochondrial function, improves glucose tolerance and pancreatic endocrine function and preserves tissue-specific glutathione (GSH)-dependent redox homeostasis in Goto-Kakizaki (GK) diabetic rats. In the current study, we have investigated the mechanism of action of aspirin in maintaining mitochondrial bioenergetics and redox metabolism in the liver and kidneys of GK rats. Aspirin reduced the production of reactive oxygen species (ROS) and oxidative stress-induced changes in GSH metabolism. Aspirin treatment also improved mitochondrial respiratory function and energy metabolism, in addition to regulating the expression of cell signaling proteins that were altered in diabetic animals. Ultrastructural electron microscopy studies revealed decreased accumulation of glycogen in the liver of aspirin-treated diabetic rats. Hypertrophic podocytes with irregular fusion of foot processes in the renal glomerulus and detached microvilli, condensed nuclei and degenerated mitochondria observed in the proximal convoluted tubules of GK rats were partially restored by aspirin. These results provide additional evidence to support our previous observation of moderation of diabetic complications by aspirin treatment in GK rats and may have implications for cautious use of aspirin in the therapeutic management of diabetes.

Exercise alleviates diabetic complications by inhibiting oxidative stress-mediated signaling cascade and mitochondrial metabolic stress in GK diabetic rat tissues

“…For cellular fractionation, the tissues were homogenized in H-medium (70 mM sucrose, 220 mM mannitol, 2.5 mM HEPES, 2 mM EDTA, 0.1 mM phenylmethylsulfonylfluoride, pH 7.4) at 4°C and the fractions separated by differential centrifugation and the purity of the fractions were checked as described before ( Raza et al, 2004 ; Raza et al, 2011 ; Raza et al, 2015 ). The protein concentration of the individual fractions was measured by the Bradford method ( Bradford, 1976 ) as described before ( Amiri et al, 2015 ; John et al, 2021 ; John et al, 2022 ).…”

“…Activities of mitochondrial respiratory complexes from freshly isolated mitochondria were measured in the liver and kidney of control Wistar and diabetic GK rats, with or without exercise. Activities of NADH-ubiquinone-oxidoreductase (Complex I), succinate-cytochrome c reductase (Complex II/III), and cytochrome c oxidase (Complex IV) were measured by the methods of Birch-Machin and Turnbull ( Birch-Machin and Turnbull, 2001 ) using coenzyme Q2, succinate and reduced cytochrome c as substrates as described before ( Raza et al, 2004 ; Raza et al, 2011 ; Raza et al, 2015 ; Raza et al, 2016 ; John et al, 2022 ). The total ATP levels in the mitochondrial fractions were measured using the ATP somatic cell assay kit (Sigma-Aldrich Fine Chemicals, St Louis, MO, United States) and the luminescence was read immediately using the TD-20/20 luminometer (Turner Designs, Sunnyvale, CA, United States).…”

“…This again points to the liver being proactive in the detoxification of toxicant material. Studies, including our own, have shown mitochondrial dysfunction, including depressed mitochondrial respiratory complex activities and ultra-structural abnormalities in type 1 and type 2 diabetic rat models (Raza et al, 2016;Tang et al, 2018;Liu et al, 2019;John et al, 2022). Impaired mitochondrial capacity for glycogen and lipid oxidation has also been closely related to insulin resistance of peripheral tissues and also includes reduced oxygen consumption and ATP production and increased oxidative stress and attenuation after exercise training (Qi et al, 2011).…”

“…Cytochrome P450-dependent monooxygenase enzymes play important roles in maintaining redox homeostasis and detoxification of various drugs. Our previous studies have also shown the activation of cytochrome P450 enzymes in type 1 and type 2 diabetic rat models (Raza et al, 2004;Raza et al, 2015;Raza et al, 2016;John et al, 2022). Using dimethyl nitrosamine (DMNA) and erythromycin as substrates for CYP 450 2E1 and CYP 450 3A4 respectively, we have measured CYP 450 2E1 and CYP 450 3A4 enzyme activities as described earlier.…”

“…Measurement of ROS production, NADPH oxidase (NOX) activity, and lipid and protein oxidation ROS production was measured in the liver and kidneys of exercised and sedentary control Wistar and type 2 diabetic GK rats using the DCFH-DA fluorescence method to measure the total peroxides as described before (Raza et al, 2004(Raza et al, , 2016John et al, 2021;John et al, 2022). Non-mitochondrial ROS was measured as the NADPH oxidase (NOX) activity by the lucigenin-enhanced chemiluminescence method and the luminescence signals were read immediately using the TD-20/ 20 luminometer (Turner Designs, Sunnyvale, CA, United States).…”