The inhibitory action of dithiocarbamates and carbon disulphide on malondialdehyde formation resulting from lipid peroxidation in rat liver microsomes

Protective Effects of Ozone Oxidative Postconditioning on Long-term Injury After Renal Ischemia/Reperfusion in Rat

BACKGROUND

Renal ischemia/reperfusion (I/R) injury can cause serious kidney damage (eg, acute aortic injury, chronic fibrosis). Some postconditioning treatments have been reported to protect from I/R effects. However, their mechanisms remain unclear. Here, we focused on potential protective effects of ozone on tubulointerstitial fibrosis after renal I/R injury in rats.

METHODS

Adult male rats were randomly divided into 4 groups with (1) sham-without I/R; (2) I/R-by clamping renal pedicle for 45 minutes; (3) I/R with ozone oxidative postconditioning (OzoneOP) following a 10-day reperfusion; and (4) I/R with oxygen oxidative postconditioning (OxygenOP) following a 10-day reperfusion. The kidneys were collected at 2 time points post I/R 10 days (at early phase) and 12 weeks (at late phase) and then analyzed for renal function, tissue fibrosis, and serum creatinine and urea nitrogen levels by staining and colorimetric methods. Additionally, expression levels of related fibrotic factors, such as α-smooth muscle actin, transforming growth factor β1, and phospho-Smad2, were assayed by immunochemistry staining.

RESULTS

OzoneOP treatment downregulated the α-smooth muscle actin, transforming growth factor β1, and phospho-Smad 2 protein expression in rats subjected to I/R at 10 days and 12 weeks. Moreover, it improved renal dysfunction and attenuated the patchy tubulointerstitial fibrosis.

CONCLUSION

Ourdata indicate that I/R-induced renal damage might cause severe tubulointerstitial fibrosis at the late phase, and OzoneOP treatment may inhibit this fibrotic development.

A labile sulfur in trisulfide affects cytochrome P-450 dependent lipid peroxidation in rat liver microsomes

The effects of trisulfide derivatives were studied on cytochrome P-450-dependent lipid peroxidation using rat liver microsomal systems. Cytochrome P-450-dependent lipid peroxidation was induced by carbon tetrachloride or tert-butylhydroperoxide and was evident by an increase in thiobarbituric acid-reactive substances (TBA-RS) and oxygen consumption. In these cytochrome P-450-dependent lipid peroxidation systems, pretreatment of microsome with trisulfide derivatives (cystine trisulfide and thiocyclam) significantly inhibited TBA-RS formation and oxygen consumption compared with disulfide or thiol analogs (cystine, nereistoxin, or cysteine). The labile sulfur contained in trisulfide disappeared during incubation with liver microsomes. In the CCl4-induced lipid peroxidation system, the cytochrome P-450 level and NAD(P)H-cytochrome P-450 reductase activity were significantly decreased by the addition of trisulfide derivatives. Therefore, in cytochrome P-450-dependent lipid peroxidation system, the potential effects of trisulfide appear to be mediated via enzyme inhibition. These results suggest that pretreatment of the trisulfide derivatives may affect the toxic function of exogenous xenobiotics or drugs, which are reduced by the liver enzyme cytochrome P-450 to radical species.

Induction of cystine transport and other stress proteins by disulfiram: effects on glutathione levels in cultured cells

Disulfiram (Antabuse) (DSF) has been reported to protect rats and other animals from the effects of hyperbaric hyperoxia at 4 to 6 ATA (atmospheres). In contrast, DSF and diethyldithiocarbamate (DDC), its metabolite, accelerate the toxic effects in rats of 100% oxygen at 1 to 2 ATA. We have examined the effects of DSF and DDC on glutathione (GSH) levels in bovine pulmonary artery endothelial cells and Chinese hamster ovary cells. Increases in intracellular GSH occurred 8 to 24 h after addition of DSF to the culture media. These increases in intracellular GSH were associated with increases in the rate of uptake of cystine into the cells. DDC was a less effective inducer of cystine uptake and increased intracellular GSH levels than was DSF. At the concentrations used, neither DDC nor DSF caused significant decreases in intracellular superoxide dismutase levels. Exogenous sulfhydryl compounds including GSH and cysteine partially blocked the induction of cystine transport by DSF or DDC, suggesting that the induction might be mediated through a sulfhydryl reaction between DSF and some cellular components. The increases in GSH in the cultured cells were not significant by 4 h of exposure. In contrast, other stress proteins including heme oxygenase are induced by 2 to 4 h after DSF addition. In previously reported in vivo studies, DSF treatment protected against hyperbaric oxygen damage after as little as 1 to 4 h pre-exposure. This suggests that effects of DSF exposure other than GSH augmentation may be responsible for the protective effects seen in vivo.

Antioxidant capacity of diethyldithiocarbamate in a metal independent lipid peroxidative process

2,2'-Azobis-[2-amidinopropane] initiated lipid peroxidation of egg yolk phosphatydil choline liposomes was measured by oxygen uptake and the emitted visible luminescence. Lipid peroxidation involved a chain process (kinetic chain length = 49 +/- 11) and its rate was independent of added Fe ions. Diethyldithiocarbamate (DDC) behaved as an efficient inhibitor in the microM range, being able to trap 1.05 +/- 0.25 free radicals per added molecule. The efficiency of DDC was also independent of Fe addition to the system. These results indicate that DDC is able to trap the chain carrying free radicals, showing that this compound, besides being a powerful metal chelator, is also an efficient free radical scavenger. It is proposed that the relevant step in this process involves an electron transfer from DDC to the peroxy radical LOO., LOO. + DDC- ----LOO- + DDC. followed by protonation of LOO- and dimerization of the DDC. radical.

Disulfiram is protective against postischemic cell death in the liver

The effect of the scavenger compound disulfiram (Antabus) on postischemic cell injury was investigated. Rats were subjected to 90 min of liver ischemia and 3 h of reperfusion. The extent of cell injury was evaluated morphologically by a dye exclusion test and a histochemical stain for calcium. It was found that pretreatment with disulfiram significantly reduced the number of injured cells compared to untreated controls.

Inhibition of lipid peroxidation in spinal cord homogenates by various drugs

The extent and kinetic profiles of lipid peroxidation induced with Fe2+-ascorbic acid in a homogenate of spinal cord from greyhound dogs were ascertained by measurement of the formation of malondialdehyde (MDA) and chemiluminescence in the presence of four drugs. Changes in MDA and chemiluminescence were correlated as a function of the activator or inhibitors. The kinetic profiles of chemiluminescence which were observed for 25 min after addition of the activator and individual inhibitors were similar regardless of the type of inhibitor studied. The most effective inhibition was by disulfiram which was approximately 11 and 33 times more effective than two other inhibitors, propyl gallate and promethazine, respectively, and 11,000 times more effective than D-alpha-tocopherol.