Metallothionein In Protection Research Articles

Interplay between dietary lipids and cadmium exposure in rainbow trout liver: Influence on fatty acid metabolism, metal accumulation and stress response

The present study aimed at investigating interactive effects between dietary lipids and both short- and long-term exposures to a low, environmentally realistic, cadmium (Cd) concentration. Juvenile rainbow trout were fed four isolipidic diets (31.7 g/kg) enriched in either linoleic acid (LA, 18:2n-6), alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3) or docosahexaenoic acid (DHA, 22:6n-3). From the 4th week of this 10-week experiment, the lipid level of the diet was increased (120.0 g/kg) and half of the fish fed each diet were aqueously exposed to Cd (0.3 μg/L) while the other half were not exposed to Cd (control). Fish were sampled and their liver was harvested for fatty acid profile, hepatic Cd and calcium concentrations, total glutathione level and gene expression assessment, either (i) after 4 weeks of feeding and 24 h of Cd contamination (day 29) (short-term Cd exposure) or (ii) after 10 weeks of feeding and 6 weeks of Cd contamination (day 70) (long-term Cd exposure). We found that both dietary lipids and Cd exposure influenced fatty acid homeostasis and metabolism. The hepatic fatty acid profile mostly reflected that of the diet (e.g. n-3/n-6 ratio) with some differences, including selective retention of specific long chain polyunsaturated fatty acids (LC-PUFAs) like DHA and active biotransformation of dietary LA and ALA into LC-PUFAs. Cd effects on hepatic fatty acid profiles were influenced by the duration of the exposure and the nutritional status of the fish. The effects of diet and Cd exposure on the fatty acid profiles were only sparsely explained by variation of the expression pattern of genes involved in fatty acid metabolism. The biological responses to Cd were also influenced by dietary lipids. Fish fed the ALA-enriched diet seemed to be the least affected by the Cd exposure, as they showed a higher detoxifying ability against Cd with an early upregulation of protective metallothionein a (MTa) and apoptosis regulator BCL2-Like1 (BCLx) genes, an increased long-term phospholipid synthesis and turnover and fatty acid bioconversion efficiency, as well as a lower long-term accumulation of Cd in their liver. In contrast, fish fed the EPA-enriched diet seemed to be the most sensitive to a long-term Cd exposure, with an impaired growth performance and a decreased antioxidant capacity (lower glutathione level). Our results highlight that low, environmentally realistic aqueous concentrations of Cd can affect biological response in fish and that these effects are influenced by the dietary fatty acid composition.

NmtA, a novel metallothionein of Anabaena sp. strain PCC 7120 imparts protection against cadmium stress but not oxidative stress

Metallothioneins (MTs) are low molecular weight, sulfhydryl-containing, cysteine-rich, metal-binding proteins. Eukaryotes have multiple metallothionein genes; however, there is dearth of reports on prokaryotic metallothioneins. Bacterial MTs with SmtA from Synechococcus PCC 7942 as prototype have been studied in the context of cadmium detoxification. In this study, a smtA related ORF, namely nmtA, was identified in the heterocystous, nitrogen-fixing cyanobacterium, Anabaena PCC 7120. A recombinant N-terminal histidine-tagged Anabaena NmtA protein was overexpressed in Escherichia coli and purified. The protein was identified by peptide mass fingerprinting using MALDI-TOF Mass Spectrometry as putative metallothionein of Anabaena PCC 7120 with a calculated mass of ∼6.1 kDa. While the native metallated NmtA exhibited resistance against proteolysis, metal free apo-NmtA resulting from acid and dithiothreitol (DTT) treatment could be digested by proteinase K revealing a metal dependent proteolytic protection of NmtA. Expression of nmtA in Anabaena PCC 7120 was induced evidently by cadmium, zinc and copper but not by uranium or hydrogen peroxide. Recombinant Anabaena PCC 7120 overexpressing NmtA protein revealed superior cadmium tolerance but showed limited influence against oxidative stress tolerance as compared with the strain carrying vector alone. In contrast, a mutant of Synechococcus PCC 7942 deficient in MT locus was found to be highly susceptible to H2O2 indicating a likely involvement of cyanobacterial MT in protection against oxidative damage. Overall, the study improved our understanding of metal tolerance mechanisms in Anabaena PCC 7120 by demonstrating a key role of NmtA in cadmium tolerance.

Differential protein expression in metallothionein protection from depleted uranium-induced nephrotoxicity.

The purpose of this study was to investigate the underlying mechanism of metallothionein (MT) protection from depleted uranium (DU) using a proteomics approach to search for a DU toxicity-differential protein. MT−/− and MT+/+ mice were administrated with a single dose of DU (10 mg/kg, i.p.) or equal volume of saline. After 4 days, protein changes in kidney tissues were evaluated using a proteomics approach. A total of 13 differentially expressed proteins were identified using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The validating results showed that the expression of aminoacylase-3 (ACY-3) and the mitochondrial ethylmalonic encephalopathy 1 (ETHE1) decreased significantly after DU exposure; in addition, the reduction in MT−/− mice was more significant than that in MT+/+ mice. The results also showed that exogenous ETHE1 or ACY-3 could increase the survival rate of human embryonic kidney 293 (HEK293) cells after DU exposure. A specific siRNA of ETHE1 significantly increased cell apoptosis rates after DU exposure, whereas exogenous ETHE1 significantly decreased cell apoptosis rates. In summary, ACY-3 and ETHE1 might involve in protection roles of MT. ETHE1 could be a new sensitive molecular target of DU-induced cell apoptosis.

Metallothionein Prevents Age-Associated Cardiomyopathy via Inhibiting NF-κB Pathway Activation and Associated Nitrative Damage to 2-OGD.

Cardiac-specific metallothionein (MT) overexpression extends lifespan, but the mechanism underlying the effect of MT protection against age-associated cardiovascular diseases (CVD) remains elusive. To elucidate this, male wild-type and two lines of MT-transgenic (MT-TG) mice, MM and MT-1 (cardiac-specific overexpressing MT about 10- and 80-fold, respectively) at three representative ages (2-3, 9-10, and 18-20 months), were utilized. A stable human MT2A overexpressing cardiomyocytes (H9c2MT7) was also introduced. Histomorphology and echocardiographic analysis revealed that age-associated cardiac hypertrophy, remodeling, and dysfunction were ameliorated in MT-TG mice. Also, aging-accompanied NF-κB activation, characterized by increased nuclear p65 translocation, elevated DNA-binding activity, and upregulation of inflammatory cytokines, was largely attenuated by MT overexpression. Treatment of H9c2 cardiomyocytes with tumor necrosis factor-α (TNF-α), which mimicked an inflammatory environment, significantly increased NF-κB activity, and some age-related phenotypes appeared. The NF-κB activation was further proved to be pivotal for both age-associated and TNF-α-induced nitrative damage to cardiac 2-oxoglutarate dehydrogenase (2-OGD) by virtue of NF-κB p65 gene silencing. MT inhibited NF-κB activation and associated nitrative damage to cardiac 2-OGD in both old MT-TG hearts and TNF-α-treated H9c2MT7 cardiomyocytes; these protective effects were abolished in H9c2MT7 cardiomyocytes by MT-specific gene silencing. Innovation and Conclusion: Together, these findings indicate that the protective effects of MT against age-associated CVD can be attributed mainly to its role in NF-κB inhibition and resultant alleviation of nitrative damage to 2-OGD. Antioxid. Redox Signal. 25, 936-952.

JAK2/STAT3 Pathway Mediates Protection of Metallothionein Against Doxorubicin-Induced Cytotoxicity in Mouse Cardiomyocytes.

Doxorubicin (Dox) is one of the most important anticancer agents; however, its clinical application is limited by its severe cardiotoxicity. In our previous study, we found that the gene expression levels of the Janus-activated kinase/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway were different between MT(-/-) cardiomyocytes and MT(+/+) cardiomyocytes when they were treated with Dox. Thus, this study was intended to investigate the role of JAK2/STAT3 pathway in metallothionein (MT) protection of Dox-induced cardiotoxicity. Tyrphostin AG490 (α-cyano-(3,4-dihydroxy)-N-benzylcinnamide) is a synthetic protein tyrosine kinase inhibitor which at first has been considered as a specific JAK2 inhibitor and can inhibit the JAK2/STAT3 signaling pathway. In the present study, AG490 was used to assess the role of JAK2/STAT3 in MT protection against Dox-induced cardiotoxicity. The AG490 can attenuate the MT protection by increasing lactate dehydrogenase and the number of apoptotic cells. Interestingly, pretreated with AG490, MT(-/-) cardiomyocytes were more sensitive than MT(+/+) to Dox-induced cytotoxicity as measured by reactive oxygen species generation, lipid peroxidation, and protein carbonylation. Metallothionein 1 and MT-2 messenger RNA were upregulated by Dox, and AG490 decreased the protein expression of MT-1 and MT-2. After Dox treatment, the protein expression of p-Jak2 and p-Stat3 levels was significantly increased in MT(+/+) cardiomyocytes, suggesting that the JAK2/STAT3 pathway was partially involved in MT protection against Dox-induced cardiotoxicity.

Peroxiredoxins are involved in metallothionein protection from doxorubicin cardiotoxicity

Previous studies have shown that metallothionein (MT) can antagonize the myocardiotoxicity induced by doxorubicin (Dox), a most effective anticancer agent. However, the molecular mechanisms are not well-understood. Using a proteomics approach we have detected that major peroxiredoxins (Prxs), an important redox regulating molecule family, may be involved in this process. In the present study, we assessed a link between metallothionein and peroxiredoxins. Wild-type (MT +/+) and MT −/− mice were treated intraperitoneally with doxorubicin at a single dose of 15 mg/kg and sacrificed on the 4th day after treatment. Doxorubicin induced cardiotoxicity in both wild-type and MT −/− mice was manifested with increased serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities, and cardiac morphological changes. These toxic responses were stronger in the hearts of MT −/− mice that were more vulnerable to doxorubicin-induced oxidative injury as exhibited by increased lipid peroxidation and decreased catalase and glutathione peroxidase (GSH-Px) expression. Moreover, in the MT −/− mice, the deficiency of metallothionein inhibited the expression of Cu/Zn Superoxide dismutase (SOD-1) induced by doxorubicin. Doxorubicin significantly increased the mRNA levels and protein expressions of Prx-1, -2, -3, -5, and -6 in the hearts of wild-type but not MT −/− mice. Therefore, the present study suggests that metallothionein provides protection against doxorubicin-induced cardiotoxicity, which possibly involves regulation of peroxiredoxins.

Hypoxia‐inducible factor 1α is critically involved in metallothionein protection against diabetic cardiomyopathy

Previous studies have shown that metallothionein (MT) protects against diabetic cardiomyopathy (DCM) in mice. The current study was undertaken to test the hypothesis that the protective role of MT against DCM is mediated by hypoxia‐inducible factor ‐1 (HIF‐1) pathway leading to an increased angiogenesis and a normalization of glucose metabolism in a MT cardiac specific over‐expression mouse model and a rat embryonic cardiac fibroblast H9c2 cell line. Streptozotocin‐induced diabetes decreased cardiac HK‐II protein level, a HIF target and an important glycolysis enzyme; and cardiac‐specific MT over‐expression relieved this suppression. MT over‐expression increased HK‐II mRNA level nder both non‐diabetic and diabetic conditions. In vitro analysis showed that MT over‐expression increased and normalized the hyperglycemia‐reduced glycolysis. MT over‐expression significantly prevented the diabetes‐induced reduction in angiogenesis. Further studies showed that MT over‐expression increased HIF‐1α mRNA and protein level in diabetic heart and in MT stable over‐expressing H9c2 cells, indicating the transcriptional modulation of HIF‐1α by MT. This study demonstrated that MT increased HIF‐1 transcriptional activity leading to the normalization of glycolysis and angiogenesis in cardiomyocytes under diabetic conditions. Supported by a grant from American Diabetes Association (W.F)

Hypoxia‐inducible Factor 1α is Critically Involved in Metallothionein Protection against Diabetic Cardiomyopathy

The purpose of this study was to examine whether or not MT affects HIF‐1α activity in the heart of diabetic mice and in the cardiac cells leading to the regulation of angiogenic factors and glycolytic enzymes. Diabetes decreased cardiac VEGF and HK‐II protein level in mice; both cardiac‐specific MT and HIF‐1α over‐expression could relieve this suppression. Further analysis showed that MT over‐expression increased HIF‐1α protein level in diabetic heart. MT rescues HIF‐1α transcriptional activity leading to normalization of VEGF and HK‐II in cardiomyocytes under diabetic conditions. (Supported in part by an American Diabetes Association Grant 07‐07‐JF‐23)

European eel ( Anguilla anguilla L.) metallothionein, endocrine, metabolic and genotoxic responses to copper exposure

This study investigated Anguilla anguilla (European eel) physiological and genotoxic responses to copper (Cu) and their relation with metallothionein (MT) protection. Eels were exposed during 7 days to Cu 0.2 μmol/L. MT induction was assessed in gill and liver, revealing significant response only in liver. Endocrine responses displayed a plasma free triiodothyronine (T3) and cortisol significant decrease, though the thyroid-stimulating hormone (TSH) and free thyroxine (T4) concentrations were unaltered. A significant plasma glucose increase was observed whereas lactate was significantly decreased. Despite the absence of DNA integrity decrease in blood, gill, liver and kidney, erythrocytic nuclear abnormalities (ENA) frequency significantly increased in Cu exposed group. MT induction was insufficient to prevent endocrine and metabolic alterations as well as genotoxicity/clastogenicity in blood. However, MT protection was evident in liver by preventing DNA integrity loss. Globally, it was demonstrated that Cu environmentally realistic levels may pose a serious ecological risk to fish.

Antioxidant defense against anthracycline cardiotoxicity by metallothionein

Anthracycline cardiotoxicity is related to oxidative stress generated from the metabolism of anthracyclines in the heart. Studies using transgenic mice with high levels of antioxidants such as catalase or metallothionein (MT) specifically in the heart have demonstrated that elevation of cardiac antioxidant defense leads to intervention of anthracycline cardiotoxicity. MT protection against anthracycline-induced cardiac toxicity is related to its anti-apoptotic effect by inhibiting both p38-MAPK-mediated and mitochondrial cytochrome c-release-mediated apoptotic signaling. The anti-apoptotic effect of MT is closely related to its antioxidant action, which involves regulation of zinc homeostasis by the MT redox cycle. MT interferes with oxidant-mediated detrimental process through at least in part zinc release and zinc transfers directly from MT to acceptor proteins. In addition, MT posttranslationally modulates critical proteins involved in mitochondrial respiration and energy metabolism. All of these processes constitute the mechanisms by which MT protects from anthracycline cardiotoxicity.

The Role of Zinc Sulfate and Metallothionein in Protection Against Ethanol-Induced Gastric Damage in Rats

In this study, the effects of zinc sulfate against ethanol-induced acute gastric damage in rats were investigated, morphologically and biochemically. In addition, the present investigation has demonstrated the distribution of metallothionein stimulated by zinc in gastric mucosal tissues, immunohistochemically. The gastric damage was induced by intragastric administration of 1 ml absolute ethanol per rat. Rats received zinc sulfate (100 mg/kg/day) for 3 consecutive days 2 hr prior to the administration of absolute ethanol. Acute ethanol exposure caused degenerative morphological changes, a decrease in metallothionein immunreactivity; an increase in lipid peroxidation (LPO) levels, and a decrease in reduced glutathione (GSH) levels in gastric mucosa. On the other hand, zinc sulfate administration to ethanol-treated rats caused a significant reduction in the histological damage, an increase in metallothionein immunreactivity, a decrease in LPO levels, and an increase in GSH levels in gastric mucosa. As a result, the present study indicates that zinc sulfate has a protective effect against ethanol-induced acute gastric damage. In addition, we might say that the zinc given as exogenous protection against acute gastric damage has a protective effect both by stimulation of metallothionein synthesis and through GSH as well as having antioxidative potential.

Modulation of Cytochrome c Oxidase-Va Is Possibly Involved in Metallothionein Protection from Doxorubicin Cardiotoxicity

Previous studies using a cardiac-specific metallothionein (MT)-overexpressing transgenic (MT-TG) mouse model have demonstrated that MT protects from doxorubicin (DOX)-induced oxidative heart injury. The molecular mechanisms that underlie this cardioprotection, however, have yet to be defined. In the present study, we tested the hypothesis that MT overexpression activates cytoprotective mechanisms, leading to cardiac protection from DOX toxicity. MT-TG mice and nontransgenic wild-type (WT) controls were treated i.p. with DOX at a single dose of 20 mg/kg and sacrificed on the third day after the treatment. An expression proteomic analysis involving two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry was used to identify MT-induced changes in cytoprotection-related proteins. We identified 18 proteins that were modified by DOX treatment in the heart. These proteins included those involved in cellular antioxidant defense, enzymes of the mitochondrial electron transport chain, enzymes involved in beta-oxidation of fatty acids and glycolysis, and proteins involved in regulation of cardiac muscle contraction. However, the most dominant modification by MT is the cytochrome c oxidase subunit Va (CCO-Va). In response to DOX treatment, a specific isoform of CCO-Va was enhanced in the MT-TG but not in the WT mouse hearts. Because CCO-Va is a critical component in the mitochondrial electron transport chain, the results suggest that the cardioprotective effect of MT may be related to an increased expression or a differential modification of CCO-Va.

Zinc Supplementation Prevents Alcoholic Liver Injury in Mice through Attenuation of Oxidative Stress

Alcoholic liver disease is associated with zinc decrease in the liver. Therefore, we examined whether dietary zinc supplementation could provide protection from alcoholic liver injury. Metallothionein-knockout and wild-type 129/Sv mice were pair-fed an ethanol-containing liquid diet for 12 weeks, and the effects of zinc supplementation on ethanol-induced liver injury were analyzed. Zinc supplementation attenuated ethanol-induced hepatic zinc depletion and liver injury as measured by histopathological and ultrastructural changes, serum alanine transferase activity, and hepatic tumor necrosis factor-alpha in both metallothionein-knockout and wild-type mice, indicating a metallothionein-independent zinc protection. Zinc supplementation inhibited accumulation of reactive oxygen species, as indicated by dihydroethidium fluorescence, and the consequent oxidative damage, as assessed by immunohistochemical detection of 4-hydroxynonenal and nitrotyrosine and quantitative analysis of malondialdehyde and protein carbonyl in the liver. Zinc supplementation suppressed ethanol-elevated cytochrome P450 2E1 activity but increased the activity of alcohol dehydrogenase in the liver, without affecting the rate of blood ethanol elimination. Zinc supplementation also prevented ethanol-induced decreases in glutathione concentration and glutathione peroxidase activity and increased glutathione reductase activity in the liver. In conclusion, zinc supplementation prevents alcoholic liver injury in an metallothionein-independent manner by inhibiting the generation of reactive oxygen species (P450 2E1) and enhancing the activity of antioxidant pathways.

Differential sensitivity of three marine invertebrates to copper assessed using multiple biomarkers

Understanding how biomarkers relate to each other on exposure to particular contaminants in different species is key to their widespread application in environmental management. However, few studies have systematically used multiple biomarkers in more than a single species to determine the variability of sublethal effects of a particular contaminant. In this study, three marine invertebrates, the shore crab Carcinus maenas, the common limpet Patella vulgata and the blue mussel Mytilus edulis, were exposed over 7 days in the laboratory to environmentally realistic concentrations of the priority pollutant copper. A combination of molecular, cellular and physiological biomarkers was measured in each organism to detect the toxic effects of copper. Biomarkers included lysosomal stability (neutral red retention), neurotoxicity (acetylcholinesterase activity), metabolic impairment (total haemolymph protein), physiological status (heart rate) and induction of protective metallothionein proteins. P. vulgata was the most sensitive to copper with significant effects measured in all biomarkers at concentrations of 6.1 μg Cu l −1. In C. maenas, cellular and neurotoxic endpoints were affected significantly only at 68.1 μg Cu l −1. Exposure to copper also induced metallothionein production in crabs. Over a 7-day exposure period, M. edulis was the most tolerant species to copper with significant effects being observed at the cellular level only at 68.1 μg Cu l −1. In all three species, cellular and neurotoxic pathways were more sensitive to disruption than physiological processes (protein and heart rate). Results illustrate how a suite of biomarkers applied to different sentinel species can provide a ‘diagnosis of stress’, whereby, effects at the molecular level can be used to interpret the level of physiological impairment of the organism.

Metallothionein protection against alcoholic liver injury through inhibition of oxidative stress.

Antioxidants are likely potential pharmaceutical agents for the treatment of alcoholic liver disease. Metallothionein (MT) is a cysteine-rich protein and functions as an antioxidant. This study was designed to determine whether MT confers resistance to acute alcohol-induced hepatotoxicity and to explore the mechanistic link between oxidative stress and alcoholic liver injury. MT-overexpressing transgenic and wild-type mice were administrated three gastric doses of alcohol at 5 g/kg. Liver injury, oxidative stress, and ethanol metabolism-associated changes were determined. Acute ethanol administration in the wild-type mice caused prominent microvesicular steatosis, along with necrosis and elevation of serum alanine aminotransferase. Ultrastructural changes of the hepatocytes include glycogen and fat accumulation, organelle abnormality, and focal cytoplasmic degeneration. This acute alcohol hepatotoxicity was significantly inhibited in the MT-transgenic mice. Furthermore, ethanol treatment decreased hepatic-reduced glutathione, but increased oxidized glutathione along with lipid peroxidation, protein oxidation, and superoxide generation in the wild-type mice. This hepatic oxidative stress was significantly suppressed in the MT-transgenic mice. However, MT did not affect the ethanol metabolism-associated decrease in NAD(+)/NADH ratio or increase in cytochrome P450 2E1. In conclusion, MT is an effective agent in cytoprotection against alcohol-induced liver injury, and hepatic protection by MT is likely through inhibition of alcohol-induced oxidative stress.

33] Mouse astrocyte cultures used to study antioxidant property of metallothionein isoforms

Publisher Summary Metallothioneins (MTs) are low molecular weight and cysteine-rich intracellular proteins that bind both essential (zinc and copper) and toxic (cadmium and mercury) metals with high affinity. They have no known enzymatic activity and are not essential, but their induced synthesis is important in the detoxification of toxic metals, and also protection against reactive-free radicals. The many nucleophilic thiol-rich groups in MT can react with various electrophilic chemicals, can participate in controlling the intracellular redox potential, and may scavenge free radicals generated during the metabolism of xenobiotics. In addition, the induction of MT synthesis in oxidative stress and exposure to various organic compounds, anticancer drugs, and ionizing radiation suggests a role for MT in protection against free radical toxicity.

Mechanism of metallothionein protection against acute alcoholic hepatotoxicity in mice

Mechanism of metallothionein protection against acute alcoholic hepatotoxicity in mice

Mechanism of metallothionein protection against acute alcoholic hepatotoxicity in mice

Mechanism of metallothionein protection against acute alcoholic hepatotoxicity in mice

Protective role of zinc-metallothionein on DNA damage in vitro by ferric nitrilotriacetate (Fe–NTA) and ferric salts

Oxidative DNA damage can be caused by radicals generated by transitional metals like iron in Fenton reaction. Metallothionein (MT) may play an important role in preventing oxidative DNA damage. Therefore, after comparing the effects of ferric salts (Fe), and complexes of ferric salts with nitrilotriacetic acid (Fe–NTA) on DNA damage, the protective effects of zinc-MT (Zn-MT) on DNA damage of Fe salts or Fe–NTA were investigated in vitro. DNA damage was measured by loss of fluorescence of DNA binding to ethidium bromide, and also by increased DNA mobility in agarose gel electrophoresis. Both Fe salts and Fe–NTA could induce calf thymus DNA damage in presence of hydrogen peroxide and ascorbate. However, the degree of DNA damage was lower with Fe salts than that with Fe–NTA complex. Addition of 50 μM Zn-MT could only protect DNA from Fe–NTA, but not from Fe salt induced damage. The protective effect of MT was about five times better than that of glutathione (GSH). These results suggest a potential role for MT in protection from Fe–NTA-induced DNA damage.

Role of Metallothionein in Protection against Renal Oxidative Stress Induced by cis-Diamminedichloroplatinum (II) in Glutathione-Depleted Mice.

The protective role of metallothionein (MT) against renal lipid peroxidation caused by administration of cis-diamminedichloroplatinum (II) (cis-DDP) was examined in glutathione (GSH)-depleted mice. Pretreatment with DL-buthionine-SR-sulfoximine (BSO), an inhibitor of GHS synthesis, 4 hr prior to injection of a subtoxic dose of cis-DDP (45 μmol/kg) significantly induced renal toxicity of this anticancer drug evaluated by an increase in blood urea nitrogen (BUN) levels. Renal levels of thiobarbituratereactive substances (TBA-RS), determined as an indicator for lipid peroxidation, were also significantly increased in BSO-treated mice by cis-DDP in advance of the increase in BUN values. The BSO-enhanced renal lipid peroxidation induced by cis-DDP was found to be attenuated by pre-administration of zinc chloride, an inducer of MT synthesis. Binding of platinum to MT in the kidneys of mice after cis-DDP administration was not increased by pretreatment with zinc chloride. A significant decrease in concentration of preinduced-MT was observed after administration of cis-DDP. This result suggests that MT may prevent the lipid peroxidation by scavenging free radicals generated by cis-DDP, but not by binding directly to cis-DDP or its metabolites, in GSH-depleted mice. The present findings support the view that MT may substitute for GSH as a scavenger of radicals produced by cis-DDP.