ABSTRACT
The trace elements such as iron are vital for various enzyme activities and for other cellular proteins, but iron toxicity causes the production of reactive oxygen species (ROS) that causes alterations in morphology and function of the nephron. The present study was designed to determine the effect of long-term iron overload on the renal antioxidant system and to determine any possible correlation between enzymatic and molecular levels. Our data showed that reduced glutathione (GSH) levels, which is a marker for oxidative stress, strikingly decreased with a long-term iron overload in rat kidney. While renal mRNA levels of glucose 6-phosphate dehydrogenase (G6pd), 6-phosphogluconate dehydrogenase (6pgd) and glutathione peroxidase (Gpx) were significantly affected in the presence of ferric iron, no changes were seen for glutathione reductase (Gsr) and glutathione S-transferases (Gst). While the iron affected the enzymatic activity of G6PD, GSR, GST, and GPX, it had no significant effect on 6PGD activity in the rat kidney. In conclusion, we reported here that the gene expression of G6pd, 6pgd, Gsr, Gpx, and Gst did not correlate to enzyme activity, and the actual effect of long-term iron overload on renal antioxidant system is observed at protein level. Furthermore, the influence of iron on the renal antioxidant system is different from its effect on the hepatic antioxidant system.
Subject(s)
Chlorides/poisoning , Ferric Compounds/poisoning , Gene Expression Regulation, Enzymologic/drug effects , Iron Overload/enzymology , Kidney/drug effects , Oxidative Stress/drug effects , Oxidoreductases/metabolism , Water Pollutants, Chemical/poisoning , Animals , Biomarkers/metabolism , Chlorides/administration & dosage , Dose-Response Relationship, Drug , Enzyme Induction/drug effects , Ferric Compounds/administration & dosage , Glucosephosphate Dehydrogenase/chemistry , Glucosephosphate Dehydrogenase/genetics , Glucosephosphate Dehydrogenase/metabolism , Glutathione/metabolism , Glutathione Peroxidase/chemistry , Glutathione Peroxidase/genetics , Glutathione Peroxidase/metabolism , Glutathione Transferase/chemistry , Glutathione Transferase/genetics , Glutathione Transferase/metabolism , Iron Overload/metabolism , Kidney/enzymology , Kidney/metabolism , Male , Oxidation-Reduction , Oxidoreductases/chemistry , Oxidoreductases/genetics , Phosphogluconate Dehydrogenase/chemistry , Phosphogluconate Dehydrogenase/genetics , Phosphogluconate Dehydrogenase/metabolism , RNA, Messenger/metabolism , Random Allocation , Rats, Sprague-Dawley , Reproducibility of Results , Water Pollutants, Chemical/administration & dosageABSTRACT
Reactive oxygen species (ROS) are highly reactive and oxygen-containing molecules that are derived by metabolic activities or from environmental sources. Toxicity of heavy metals including iron has the ability to generate ROS in all living organisms. The pentose phosphate pathway enzymes, which are glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, produce nicotinamide adenine dinucleotide phosphate (NADPH) that enables cells to counterbalance the oxidative stress via the action of the glutathione system. The results presented here have shown that toxic and nontoxic levels of iron have a strong effect on the expression of both genes. While toxic levels of iron exhibited significant changes in enzyme activity, nontoxic levels had no effect on enzymes in rat liver. Our results are the first evidence to elucidate how oxidative stress induced by long-term iron toxicity affects both enzymes at the enzymatic and molecular level and also to determine any possible correlation between the enzymatic and molecular levels.
Subject(s)
Chlorides/toxicity , Ferric Compounds/toxicity , Gene Expression/drug effects , Glucosephosphate Dehydrogenase/genetics , Liver/drug effects , Oxidative Stress/drug effects , Phosphogluconate Dehydrogenase/genetics , Animals , Glutathione/metabolism , Liver/enzymology , Liver/metabolism , Male , Oxidative Stress/genetics , RNA/genetics , Rats, Sprague-Dawley , Real-Time Polymerase Chain ReactionABSTRACT
The free radicals within the body, produced by metabolic activities or derived from environmental sources are relatively related to hepatoxicity. Since heavy metals including iron have the ability to produce free radicals, the liver glutathione system neutralizes them to protect cells against any damage. The objective of this study is to indicate the toxic effects of iron on the glutathione system at the enzymatic and molecular level. Thus, any possible correlation between enzymatic and molecular levels can be determined. According to our results, while mRNA expression of glutathione reductase (Gsr) and glutathione S-transferases (Gsta5) genes were not affected by long-term exposure to various concentrations of iron (Fe(3+)), transcription level of glutathione peroxidase (Gpx2) was influenced in the presence of toxic iron. Whereas the enzyme activites of GSR (GR), GPX and GST were significantly affected in rat liver.
