1-3-dimethylthiourea and Kidney-Diseases

Nephrotoxicity is the major dose-limiting factor of cisplatin chemotherapy. Reactive oxygen species generated in mitochondria are thought to be the main cause of cellular damage in such injury. The present study examined, in vivo, the protective potential of the hydroxyl radical scavenger dimethylthiourea (DMTU) against cisplatin-induced effects on renal mitochondrial bioenergetics, redox state and oxidative stress. Adult male Wistar rats (200 to 220 g) were divided into four groups of eight animals each. The control group was treated only with an intraperitoneal (i.p.) injection of saline solution (1 ml/100 g body weight). The second group was given only DMTU (500 mg/kg body weight, i.p, followed by 125 mg/Kg, i.p., twice a day until they were killed). The third group was given a single injection of cisplatin (10 mg/kg body weight, i.p.). The fourth group was given DMTU (500 mg/kg body weight, i.p.), just before the cisplatin injection (10 mg/kg body weight, i.p.), followed by injections of DMTU (125 mg/kg body weight, i.p.) twice a day until they were killed. Animals were killed 72 h after the treatment. Besides not presenting any direct effect on mitochondria, DMTU substantially inhibited cisplatin-induced mitochondrial injury and cellular death by apoptosis, suppressing the occurrence of acute renal failure. All the following cisplatin-induced effects were prevented by DMTU: (1) increased plasmatic levels of creatinine and blood urea nitrogen (BUN); (2) decreased ATP content, calcium uptake and electrochemical potential; (3) oxidation of lipids, including cardiolipin; and oxidation of proteins, including sulfhydryl, and aconitase enzyme, as well as accumulation of carbonyl proteins; (4) depletion of the antioxidant defense (NADPH and GSH) and (5) increased activity of the apoptosis executioner caspase-3. Our findings show the important role played by mitochondria and hydroxyl radicals in cisplatin-induced nephrotoxicity, as well as the effectiveness of DMTU in preventing the renal mitochondrial damage caused by cisplatin. These results strongly suggest that protection of mitochondria by hydroxyl radical scavengers may be an interesting approach to prevent the kidney tissue damage caused by cisplatin-chemotherapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Blood Urea Nitrogen; Cisplatin; Creatinine; Energy Metabolism; Free Radical Scavengers; Glutathione; Kidney; Kidney Diseases; Lipid Peroxidation; Male; Membrane Potentials; Mitochondria; NADP; Oxidation-Reduction; Oxidative Stress; Rats; Rats, Wistar; Thiourea

Cisplatin is an important chemotherapeutic agent but can cause acute renal injury. Part of this acute renal injury is mediated through tumor necrosis factor-alpha (TNF-alpha). The pathway through which cisplatin mediates the production of TNF-alpha and injury is not known. Cisplatin activates p38 MAPK and induces apoptosis in cancer cells. p38 MAPK activation leads to increased production of TNF-alpha in ischemic injury and in macrophages. However, little is known concerning the role of p38 MAPK in cisplatin-induced renal injury. Therefore, we examined the effect of cisplatin on p38 MAPK activity and the role of p38 MAPK in mediating cisplatin-induced TNF-alpha production and renal injury. In vitro, cisplatin caused a dose-dependent activation of p38 MAPK in proximal tubule cells. Inhibition of p38 MAPK activation led to inhibition of TNF-alpha production. In vivo, mice treated with a single dose of cisplatin (20 mg/kg body wt) developed severe renal dysfunction at 72 h [blood urea nitrogen (BUN): 154 +/- 34 mg/dl, creatinine: 1.4 +/- 0.4 mg/dl], which was accompanied by an increase in kidney p38 MAPK activity and an increase in infiltrating leukocytes. However, animals treated with the p38 MAPK inhibitor SKF-86002 along with cisplatin showed less renal dysfunction (BUN: 55 +/- 14 mg/dl, creatinine: 0.3 +/- 0.02 mg/dl, P < 0.05), less severe histological damage, and fewer leukocytes compared with cisplatin+vehicle-treated animals. Serum levels of TNF-alpha, sTNFRI, and sTNFRII also increased significantly in cisplatin-treated mice compared with SKF-86002-treated mice (P < 0.05). Kidney mRNA levels of TNF-alpha were significantly increased in cisplatin-treated mice compared with either SKF-86002- or saline-treated animals. The hydroxyl radical scavenger DMTU (100 mg.kg body wt(-1).day(-1)) prevented the activation of p38 MAPK by cisplatin both in vitro and in vivo. DMTU also completely prevented cisplatin-induced renal injury (BUN: 140 +/- 27 vs. 22 +/- 2 mg/dl, P < 0.005) and the increase in serum TNF-alpha (33 +/- 7 vs. 4 +/- 2 pg/ml, P < 0.005) and kidney TNF-alpha mRNA in vivo. We conclude that hydroxyl radicals, either directly or indirectly, activate p38 MAPK and that p38 MAPK plays an important role in mediating cisplatin-induced acute renal injury and inflammation, perhaps through production of TNF-alpha.

Topics: Animals; Cell Line; Cisplatin; Enzyme Activation; Enzyme Inhibitors; Free Radical Scavengers; Imidazoles; Kidney Diseases; Male; Mice; Mice, Inbred C57BL; p38 Mitogen-Activated Protein Kinases; Pyridines; Reactive Oxygen Species; Thiazoles; Thiourea; Tumor Necrosis Factor-alpha

We evaluated the roles of reactive oxygen species and intrinsic antioxidant enzymes in the development of daunomycin (DM)-induced nephropathy in mice. A single dose of DM (20 mg/kg intravenously) induced proteinuria by day 7 and the nephrotic syndrome by day 14 in DM-sensitive strain (A/J) but not in DM-resistant strain (C57BL/6J) (B6). Renal cortical lipid peroxide levels in the A/J mice significantly increased at days 2, 4, and 7 after DM injection, whereas no increase was observed in the B6 mice. The resistance to DM in B6 mice was associated with higher activities in renal cortical superoxide dismutase and glutathione peroxidase. The administration of superoxide dismutase or of dimethylthiourea significantly suppressed the DM-induced proteinuria in the A/J mice. Four days of superoxide dismutase or dimethylthiourea administration suppressed the proteinuria. These findings suggested that murine DM-nephropathy appeared to be mediated by reactive oxygen species and that intrinsic antioxidant enzyme activities may play an important role in the susceptibility to DM-induced nephropathy in mice.

Topics: Albuminuria; Animals; Catalase; Daunorubicin; Free Radical Scavengers; Glutathione; Glutathione Peroxidase; Kidney; Kidney Diseases; Lipid Peroxides; Male; Mice; Mice, Inbred Strains; Nephrotic Syndrome; Reactive Oxygen Species; Serum Albumin; Superoxide Dismutase; Thiourea

Studies were performed to examine the mechanisms for the protective effects of free radical scavengers on gentamicin (GM)-mediated nephropathy. Administration of GM at 40 mg/kg sc for 13 days to rats induced a significant reduction in renal blood flow (RBF) and inulin clearance (CIn) as well as marked tubular damage. A significant reduction in urinary guanosine 3',5'-cyclic monophosphate (cGMP) excretion and a significant increase in renal cortical renin and endothelin-1 contents were also observed in GM-mediated nephropathy. Superoxide dismutase (SOD) or dimethylthiourea (DMTU) significantly lessened the GM-induced decrement in CIn. The SOD-induced increase in glomerular filtration rate was associated with a marked improvement in RBF, an increase in urinary cGMP excretion, and a decrease in renal renin and endothelin-1 content. SOD did not attenuate the tubular damage. In contrast, DMTU significantly reduced the tubular damage and lipid peroxidation, but it did not affect renal hemodynamics and vasoactive substances. Neither SOD nor DMTU affected the renal cortical GM content in GM-treated rats. These results suggest that 1) both SOD and DMTU have protective effects on GM-mediated nephropathy, 2) the mechanisms for the protective effects differ for SOD and DMTU, and 3) superoxide anions play a critical role in GM-induced renal vasoconstriction.

Topics: Acetylglucosaminidase; Animals; Cyclic GMP; Endothelins; Free Radical Scavengers; Gentamicins; Kidney; Kidney Diseases; Lipid Peroxides; Male; Rats; Rats, Sprague-Dawley; Renal Circulation; Renin; Superoxide Dismutase; Thiourea

Hypoxic injury in the isolated perfused rat kidney (IPRK) was monitored using 23Na-NMR in the presence or absence of 1.5 and 15 mM dimethylthiourea (DMTU) or 15 mM dimethylsulphoxide (DMSO) before and after inducing hypoxia. Hypoxia induced a prompt exponential increase in total renal 23Na+, renal vascular resistance, and sodium excretion and decreased inulin clearance and adenine nucleotides and reduced glutathione concentrations. Lipid peroxide metabolites were unaltered. The increase in 23Na+ was significantly reduced (P < 0.001) by both DMTU and DMSO although hypoxic perturbations of function and biochemical parameters were not. Posthypoxic increases in renal 23Na+ include approximately 10% from the intratubular compartment, but principally reflect the intracellular and interstitial compartments. The results demonstrate that 23Na-NMR is a sensitive indicator of hypoxic renal injury in intact kidney and suggest that DMTU and DMSO protect against hypoxic injury by a mechanism independent of free radical-binding.

Topics: Animals; Dimethyl Sulfoxide; Hypoxia; Kidney Diseases; Magnetic Resonance Spectroscopy; Male; Rats; Rats, Wistar; Sodium; Thiourea

Glutathione (GSH) metabolism, a tissue detoxification pathway, was evaluated in rats with adriamycin nephrosis (AN) treated with dimethylthiourea (DMTU), a free radical scavenger. After 7 days of DMTU, a significant reduction in proteinuria occurred as compared to AN controls (62.4 +/- 13.3 vs. 155.0 +/- 24.0 mg/24 h). A significant increase in renal cortical GSH content as well as glutathione peroxidase (GP) and transferase (GT) activities occurred in DMTU-treated rats as compared to controls. Glutathione monoethyl ester (GME) administration alone reduced proteinuria by 21% in AN, which was not significant despite a large increase in the renal GSH content, however, GP and GT activities were not increased by GME. We conclude that DMTU ameliorates glomerular injury in AN by stimulating GSH metabolism.

Topics: Animals; Doxorubicin; Glutathione; Kidney Cortex; Kidney Diseases; Male; Proteinuria; Rats; Rats, Sprague-Dawley; Thiourea

Toxic O2 metabolites have been postulated to contribute to renal ischemia-reperfusion injury, but their biochemical assessment and contribution as a function of the duration of ischemia is unclear. To address this issue we measured renal function and renal cortical glutathione levels following 20, 30, or 45 min of ischemia in situ and then 60 min of reperfusion by the isolated kidney technique. Increasing durations of ischemia were associated with progressive decreases in perfusion flow rate, glomerular filtration rate, tubular Na reabsorption, and renal cortical glutathione following reperfusion. However, reperfusion following simultaneous addition of the permeable O2 metabolite scavenger dimethylthiourea (DMTU; but not urea) prevented glutathione consumption and attenuated reperfusion-induced injury after 20 and 30 min of ischemia. In contrast, reperfusion with DMTU prevented glutathione consumption but did not improve renal function after 45 min of ischemia. Similarly, reperfusion with dimethyl sulfoxide also attenuated renal injury after 20 and 30 min, but not after 45 min of ischemia. Thus reperfusion of kidneys made ischemic for 20 or 30 min is associated with decreases in tissue glutathione and renal function that were both inhibitable by addition of O2 metabolite scavengers during reperfusion. In contrast, addition of O2 metabolite scavengers during reperfusion of kidneys previously made ischemic for 45 min prevented decreases in glutathione but did not improve renal function. We conclude that O2 metabolites formed during reperfusion contribute to functional impairment in kidneys made ischemic for short durations up to 30 min) but that after prolonged ischemia (greater than 30 min) injury is primarily mediated by non-O2 metabolite-dependent cellular events.

Topics: Animals; Dimethyl Sulfoxide; Glomerular Filtration Rate; Glutathione; Ischemia; Kidney Diseases; Male; Oxygen; Perfusion; Rats; Rats, Inbred Strains; Thiourea