Metallothionein protects DNA from oxidative damage

Copper induces neuron-sparing, ferredoxin 1-independent astrocyte toxicity mediated by oxidative stress

Copper is an essential enzyme cofactor in oxidative metabolism, anti-oxidant defenses, and neurotransmitter synthesis. However, intracellular copper, when improperly buffered, can also lead to cell death. Given the growing interest in the use of copper in the presence of the ionophore elesclomol (CuES) for the treatment of gliomas, we investigated the effect of this compound on the surround parenchyma-namely neurons and astrocytes in vitro. Here, we show that astrocytes were highly sensitive to CuES toxicity while neurons were surprisingly resistant, a vulnerability profile that is opposite of what has been described for zinc and other toxins. Bolstering these findings, a human astrocytic cell line was similarly sensitive to CuES. Modifications of cellular metabolic pathways implicated in cuproptosis, a form of copper-regulated cell death, such as inhibition of mitochondrial respiration or knock-down of ferredoxin 1 (FDX1), did not block CuES toxicity to astrocytes. CuES toxicity was also unaffected by inhibitors of apoptosis, necrosis or ferroptosis. However, we did detect the presence of lipid peroxidation products in CuES-treated astrocytes, indicating that oxidative stress is a mediator of CuES-induced glial toxicity. Indeed, treatment with anti-oxidants mitigated CuES-induced cell death in astrocytes indicating that oxidative stress is a mediator of CuES-induced glial toxicity. Lastly, prior induction of metallothioneins 1 and 2 in astrocytes with zinc plus pyrithione was strikingly protective against CuES toxicity. As neurons express high levels of metallothioneins basally, these results may partially account for their resistance to CuES toxicity. These results demonstrate a unique toxic response to copper in glial cells which contrasts with the cell selectivity profile of zinc, another biologically relevant metal.

Structural Role of Cadmium and Zinc in Metallothionein Oxidation by Hydrogen Peroxide: The Resilience of Metal-Thiolate Clusters

Oxidative stress is a state involving an imbalance of reactive oxygen species in a cell and is linked to a variety of diseases. The metal-binding protein metallothionein (MT) may play a role in protection due to its high cysteine content. Many studies have shown that oxidative stress will cause MT to both form disulfide bonds and release bound metals. However, studies on the more biologically relevant partially metalated MTs have been largely neglected. Additionally, most studies to date have used spectroscopic methods that cannot detect specific intermediate species. In this paper, we describe the oxidation and the subsequent metal displacement pathway of fully and partially metalated MTs with hydrogen peroxide. The rates of the reactions were monitored using electrospray ionization mass spectrometry (ESI-MS) techniques, which resolved and characterized the individual intermediate M_x(SH)_yMT species. The rate constants were calculated for each species formation. Through ESI-MS and circular dichroism spectroscopy, it was found that the three metals in the β-domain were the first to be released from the fully metalated MTs. The Cd(II) in the partially metalated Cd(II)-bound MTs rearranged to form a protective Cd₄MT cluster structure upon exposure to oxidation. The partially metalated Zn(II)-bound MTs oxidized at a faster rate as the Zn(II) did not rearrange in response to oxidation. Additionally, density functional theory calculations showed that the terminally bound cysteines were more negative and thus more susceptible to oxidation than the bridging cysteines. The results of this study highlight the importance of metal-thiolate structures and metal identity in MT's response to oxidation.

Emerging Roles of Metallothioneins in Beta Cell Pathophysiology: Beyond and Above Metal Homeostasis and Antioxidant Response

Simple Summary

Defective insulin secretion by pancreatic beta cells is key for the development of type 2 diabetes but the precise mechanisms involved are poorly understood. Metallothioneins are metal binding proteins whose precise biological roles have not been fully characterized. Available evidence indicated that Metallothioneins are protective cellular effectors involved in heavy metal detoxification, metal ion homeostasis and antioxidant defense. This concept has however been challenged by emerging evidence in different medical research fields revealing novel negative roles of Metallothioneins, including in the context of diabetes. In this review, we gather and analyze the available knowledge regarding the complex roles of Metallothioneins in pancreatic beta cell biology and insulin secretion. We comprehensively analyze the evidence showing positive effects of Metallothioneins on beta cell function and survival as well as the emerging evidence revealing negative effects and discuss the possible underlying mechanisms. We expose in parallel findings from other medical research fields and underscore unsettled questions. Then, we propose some future research directions to improve knowledge in the field.

Abstract

Metallothioneins (MTs) are low molecular weight, cysteine-rich, metal-binding proteins whose precise biological roles have not been fully characterized. Existing evidence implicated MTs in heavy metal detoxification, metal ion homeostasis and antioxidant defense. MTs were thus categorized as protective effectors that contribute to cellular homeostasis and survival. This view has, however, been challenged by emerging evidence in different medical fields revealing novel pathophysiological roles of MTs, including inflammatory bowel disease, neurodegenerative disorders, carcinogenesis and diabetes. In the present focused review, we discuss the evidence for the role of MTs in pancreatic beta-cell biology and insulin secretion. We highlight the pattern of specific isoforms of MT gene expression in rodents and human beta-cells. We then discuss the mechanisms involved in the regulation of MTs in islets under physiological and pathological conditions, particularly type 2 diabetes, and analyze the evidence revealing adaptive and negative roles of MTs in beta-cells and the potential mechanisms involved. Finally, we underscore the unsettled questions in the field and propose some future research directions.

Exposure to Dichlorodiphenyldichloroethylene (DDE) and Metallothionein Levels in Rats Fed with Normocaloric or High-Fat Diet: A Review

The growing number of studies on metallothioneins (MTs), cysteine-rich metal-binding proteins, have been disclosing new functions of these proteins. Thanks to their inducibility, they were considered to play a pivotal role in regulating trace metals homeostasis and in detoxification from heavy metals; nowadays, it is known that they are involved in various physiological and pathological processes, such as regulation of apoptosis, elimination of free radicals, and protection of nucleic acids against toxic insults. MT induction has been demonstrated following stress factors other than heavy metals, such as endocrine-disrupting chemicals, insecticides, and herbicides. However, retrieved data are often controversial: in some cases, xenobiotics elicit MT expression and synthesis; under different conditions, they lead to a decrease in cellular MT content. This review describes the MT response to dichlorodiphenyltrichloroethane (DDT) contamination in mammalian tissues. In particular, attention focuses on changes in MT expression, synthesis, and localization in rat liver, kidneys, and testes following oral administration of dichlorodiphenyldichloroethylene (DDE), the main metabolite of DDT, under normal dietary conditions or in combination with a high fat diet potentially able to increase the cellular uptake of this lipophilic pesticide. The potential connection between MT expression and synthesis, lipophilic substances and trace metals availability is also discussed.

Integrated, multicohort analysis reveals unified signature of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease that follows an unpredictable disease course and affects multiple organs and tissues. We performed an integrated, multicohort analysis of 7,471 transcriptomic profiles from 40 independent studies to identify robust gene expression changes associated with SLE. We identified a 93-gene signature (SLE MetaSignature) that is differentially expressed in the blood of patients with SLE compared with healthy volunteers; distinguishes SLE from other autoimmune, inflammatory, and infectious diseases; and persists across diverse tissues and cell types. The SLE MetaSignature correlated significantly with disease activity and other clinical measures of inflammation. We prospectively validated the SLE MetaSignature in an independent cohort of pediatric patients with SLE using a microfluidic quantitative PCR (qPCR) array. We found that 14 of the 93 genes in the SLE MetaSignature were independent of IFN-induced and neutrophil-related transcriptional profiles that have previously been associated with SLE. Pathway analysis revealed dysregulation associated with nucleic acid biosynthesis and immunometabolism in SLE. We further refined a neutropoiesis signature and identified underappreciated transcripts related to immune cells and oxidative stress. In our multicohort, transcriptomic analysis has uncovered underappreciated genes and pathways associated with SLE pathogenesis, with the potential to advance clinical diagnosis, biomarker development, and targeted therapeutics for SLE.

Mitochondrial Involvement in the Adaptive Response to Chronic Exposure to Environmental Pollutants and High-Fat Feeding in a Rat Liver and Testis

In our modern society, exposure to stressful environmental stimuli, such as pollutants and/or chronic high-fat feeding, continuously induce tissular/organ metabolic adaptation to promote cellular survival. In extreme conditions, cellular death and tissular/organ damage occur. Mitochondria, as a cellular energy source, seem to play an important role in facing cellular stress induced by these environmental stimuli. On the other hand, mitochondrial dysfunction and oxidative stress play a key role in environmental stress-induced metabolic diseases. However, little is known about the combined effect of simultaneous exposure to chronic high-fat feeding and environmental pollutants on metabolic alterations at a tissular and cellular level, including mitochondrial dysfunction and oxidative stress induction. Our research group recently addressed this topic by analysing the effect of chronic exposure to a non-toxic dose of the environmental pollutant dichlorodiphenyldichloroethylene (DDE) associated with high-fat feeding in male Wistar rats. In this review, we mainly summarize our recent findings on mitochondrial adaptive response and oxidative stress induction in the liver, the main tissue involved in fat metabolism and pollutant detoxification, and in male gonads, the main targets of endocrine disruption induced by both high-fat feeding and environmental pollutants.

Combined effects of DDE and hyperlipidic diet on metallothionein expression and synthesis in rat tissues

Metallothionein is well known for its detoxificant and anti-oxidant properties and has been shown to be effective to prevent hydroxyl radical-generated DNA degradation. The purpose of this investigation was to analyze the combined effect of two factors promoting cellular oxidative-stress, that is, the administration of the pesticide dichloro-diphenyl-dichloroethylene (DDE) and a high fat diet, on metallothionein expression and synthesis in rat liver and kidney. DDE is the main metabolite of dichloro-diphenyl-trichloroethane (DDT), and is commonly found in the food chain and in all tissues of living organisms, carried by the fats. Male Wistar rats were fed with a standard (N) or a high fat (HF) diet and exposed to DDE (10 mg/kg body mass, N + DDE and HF + DDE groups) or vehicle (corn oil, N, and HF groups) via gavage every day for 28 days. Tissues histology was determined by light microscopy analysis; differences in metallothionein gene expression and synthesis by real-time PCR and western blot, respectively. Finally, protein cellular localization was established by immunocytochemistry. The results showed a different involvement of metallothionein in defending tissues from HF- and DDE-induced oxidative stress, suggesting that hepatic and renal cells use different strategies against pro-oxidant species. In both cell types a marked increase in the metallothionein content was observed in the nucleus, with a concomitant drop of the cytoplasmatic protein, either under HF- and DDE-stress conditions; however, no synergistic or additive effects were observed between the action of fats and pesticide. These findings reinforce the role of metallothionein in protecting DNA from oxidative damage.

Comparative analysis of gene expression between renal cortex and papilla in nedaplatin-induced nephrotoxicity in rats

To elucidate the mechanism of nephrotoxicity caused by anti-neoplastic platinum complex, nedaplatin (NDP), treatment with a particular focus on the renal papillary toxicity, we analysed the gene expression profiles of two renal regions, the cortex (RC) and the papilla (RP) in rat kidneys. Male Wistar rats received a single administration of 10 mg/kg intravenous NDP or vehicle alone (5% xylitol solution) and were sacrificed six days later. The kidneys were dissected into the RC and RP and used for histopathological and microarray analyses. Histopathologically, NDP caused characteristic renal lesions, such as necrosis, single cell necrosis (with TUNEL TdT-mediated dUTP-biotin nick end labelling-positive) and regeneration/hyperplasia of the epithelial cells in both renal regions. Global gene expression analysis revealed that several genes involved in various functional categories were commonly deregulated in both renal regions, such as apoptosis, cell cycle regulation, DNA metabolism, cell migration/adhesion and cytoskeleton organization or genes induced as a perturbation of oxidative status and calcium homeostasis. Comparative analysis of gene expression between RC and RP revealed that genes encoding several subtypes of cytokeratins were identified as being specifically overexpressed in RP by the NDP treatment. Differential expression patterns of these selected genes observed by microarray analysis were further confirmed by quantitative real time RT-PCR and immunohistochemistry, which demonstrated increased expression of cytokeratins (CKs) 14 and 19 at the epithelium covering RP and/or collecting duct epithelium. Overall, the results contribute to understanding the renal molecular events of NDP-induced nephrotoxicity including novel potential biomarker genes encoding CKs 14 and 19 that may serve as indicators of renal papillary toxicity. Human & Experimental Toxicology (2007) 26, 767—780

Fluorescence-tagged metallothionein with CdTe quantum dots analyzed by the chip-CE technique

ABSTRACT

Quantum dots (QDs) are fluorescence nanoparticles (NPs) with unique optic properties which allow their use as probes in chemical, biological, immunological, and molecular imaging. QDs linked with target ligands such as peptides or small molecules can be used as tumor biomarkers. These particles are a promising tool for selective, fast, and sensitive tagging and imaging in medicine. In this study, an attempt was made to use QDs as a marker for human metallothionein (MT) isoforms 1 and 2. Four kinds of CdTe QDs of different sizes bioconjugated with MT were analyzed using the chip-CE technique. Based on the results, it can be concluded that MT is willing to interact with QDs, and the chip-CE technique enables the observation of their complexes. It was also observed that changes ranging roughly 6-7 kDa, a value corresponding to the MT monomer, depend on the hydrodynamic diameters of QDs; also, the MT sample without cadmium interacted stronger with QDs than MT saturated with cadmium. Results show that MT is willing to interact with smaller QDs (blue CdTe) rather than larger ones QDs (red CdTe). To our knowledge, chip-CE has not previously been applied in the study of CdTe QDs interaction with MT.

GRAPHICAL ABSTRACT

Overexpression of Iris. lactea var. chinensis metallothionein llMT2a enhances cadmium tolerance in Arabidopsis thaliana

Metallothioneins (MTs) are cysteine-rich, low molecular weight, heavy metal-binding protein molecules. Here, a full-length cDNA homologue of MT2a (type 2 metallothionein) was isolated from the cadmium-tolerant species Iris. lactea var. chinensis (I. lactea var. chinensis). Expression of IlMT2a in I. lactea var. chinensis roots and leaves was up-regulated in response to cadmium stress. When the gene was constitutively expressed in Arabidopsis thaliana (A. thaliana), root length of transgenic lines was longer than that of wild-type under 50μM or 100μM cadmium stress. However, there was no difference of cadmium absorption between wild-type and trangenic lines. Histochemical staining by 3,3-diaminobenzidine (DAB) and nitroblue tetrazoliu (NBT) clearly demonstrated that transgenic lines accumulated remarkably less H2O2 and O2(-) than wild-type. Together, IlMT2a may be a promising gene for the cadmium tolerance improvement.

Transcriptome profiling of the newborn mouse lung response to acute ozone exposure

Ozone pollution is associated with adverse effects on respiratory health in adults and children but its effects on the neonatal lung remain unknown. This study was carried out to define the effect of acute ozone exposure on the neonatal lung and to profile the transcriptome response. Newborn mice were exposed to ozone or filtered air for 3h. Total RNA was isolated from lung tissues at 6 and 24h after exposure and was subjected to microarray gene expression analysis. Compared to filtered air-exposed littermates, ozone-exposed newborn mice developed a small but significant neutrophilic airway response associated with increased CXCL1 and CXCL5 expression in the lung. Transcriptome analysis indicated that 455 genes were down-regulated and 166 genes were up-regulated by at least 1.5-fold at 6h post-ozone exposure (t-test, p < .05). At 24h, 543 genes were down-regulated and 323 genes were up-regulated in the lungs of ozone-exposed, compared to filtered air-exposed, newborn mice (t-test, p < .05). After controlling for false discovery rate, 50 genes were identified as significantly down-regulated and only a few (RORC, GRP, VREB3, and CYP2B6) were up-regulated at 24h post-ozone exposure (q < .05). Gene ontology enrichment analysis revealed that cell cycle-associated functions including cell division/proliferation were the most impacted pathways, which were negatively regulated by ozone exposure, an adverse effect that was associated with reduced bromo-deoxyuridine incorporation. These results demonstrate that acute ozone exposure alters cell proliferation in the developing neonatal lung through a global suppression of cell cycle function.

The role of metallothionein in oxidative stress

Free radicals are chemical particles containing one or more unpaired electrons, which may be part of the molecule. They cause the molecule to become highly reactive. The free radicals are also known to play a dual role in biological systems, as they can be either beneficial or harmful for living systems. It is clear that there are numerous mechanisms participating on the protection of a cell against free radicals. In this review, our attention is paid to metallothioneins (MTs) as small, cysteine-rich and heavy metal-binding proteins, which participate in an array of protective stress responses. The mechanism of the reaction of metallothioneins with oxidants and electrophilic compounds is discussed. Numerous reports indicate that MT protects cells from exposure to oxidants and electrophiles, which react readily with sulfhydryl groups. Moreover, MT plays a key role in regulation of zinc levels and distribution in the intracellular space. The connections between zinc, MT and cancer are highlighted.

Zn tolerance of novel Colocasia esculenta metallothionein and its domains in Escherichia coli and tobacco

Contrary to extensive researches on the roles of metallothioneins (MTs) in metal tolerance of animals, the roles of plant MTs in metal tolerance are largely under investigation. In this study, we evaluated the functional role of type 2 MT from Colocasia esculenta (CeMT2b) in Zn tolerance of tobacco and E. coli cells. Under Zn-stress conditions, transgenic tobacco overexpressing CeMT2b displayed much better seedling growth, a significant decrease in the levels of H(2)O(2) and an increase in Zn accumulation compared with the wild type. Overexpression of CeMT2b in E. coli greatly enhanced Zn tolerance and Zn accumulation under Zn stresses compared with control cells. CeMT2b bound 5.38 ± 0.29 atoms of Zn per protein. To identify a structural domain of CeMT2b for Zn binding, we investigated the growth of E. coli expressing each of the N-terminal, C-terminal, and central linker domains or a CNC motif deletion from the C-terminus of full-length CeMT2b. The results showed that the CNC motif is required for Zn tolerance, and the N-terminal domain is more effective in Zn tolerance than the C-terminal domain. Taken together, our results provide direct evidence for functional contributions of CeMT2b in Zn tolerance of tobacco and E. coli cells.

Metallothioneins and zinc in cancer diagnosis and therapy

Metallothioneins (MTs) are involved in protection against oxidative stress (OS) and toxic metals and they participate in zinc metabolism and its homeostasis. Disturbing of zinc homeostasis can lead to formation of reactive oxygen species, which can result in OS causing alterations in immunity, aging, and civilization diseases, but also in cancer development. It is not surprising that altered zinc metabolism and expression of MTs are of great interest in the case of studying of oncogenesis and cancer prognosis. The role of MTs and zinc in cancer development is tightly connected, and the structure and function of MTs are strongly dependent on Zn²⁺ redox state and its binding to proteins. Antiapoptic effects of MTs and their interactions with proteins nuclear factor kappa B, protein kinase C, esophageal cancer-related gene, and p53 as well as the role of MTs in their proliferation, immunomodulation, enzyme activation, and interaction with nitric oxide are reviewed. Utilization of MTs in cancer diagnosis and therapy is summarized and their importance for chemoresistance is also mentioned.

Clustered metallothionein genes are co-regulated in rice and ectopic expression of OsMT1e-P confers multiple abiotic stress tolerance in tobacco via ROS scavenging

BACKGROUND

Metallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, found across genera and species, but their function(s) in abiotic stress tolerance are not well documented.

RESULTS

We have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive library generated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis of the rice genome sequence revealed that this gene belongs to a multigenic family, which consists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, away from the majority of other type I genes that are clustered on chromosome XII. Various members of this MT gene cluster showed a tight co-regulation pattern under several abiotic stresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in a developmental and organ specific manner. Using transgenic approach, we found a positive correlation between ectopic expression of OsMT1e-P and stress tolerance. Our experiments further suggest ROS scavenging to be the possible mechanism for multiple stress tolerance conferred by OsMT1e-P.

CONCLUSION

We present an overview of MTs, describing their gene structure, genome localization and expression patterns under salinity and development in rice. We have found that ectopic expression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenic tobacco and the resultant plants could survive and set viable seeds under saline conditions. Taken together, the experiments presented here have indicated that ectopic expression of OsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactive oxygen species.

dHPLC efficiency for semi-automated cDNA-AFLP analyses and fragment collection in the apple scab-resistance gene model

cDNA-AFLP analysis for transcript profiling has been successfully applied to study many plant biological systems, particularly plant-microbe interactions. However, the separation of cDNA-AFLP fragments by gel electrophoresis is reported to be labor-intensive with only limited potential for automation, and the collection of differential bands for gene identification is even more cumbersome. In this work, we present the use of dHPLC (denaturing high performance liquid chromatography) and automated DNA fragment collection using the WAVE(®) System to analyze and recover cDNA-AFLP fragments. The method is successfully applied to the Malus-Venturia inaequalis interaction, making it possible to collect 66 different transcript-derived fragments for apple genes putatively involved in the defense response activated by the HcrVf2 resistance gene. The results, validated by real time quantitative RT-PCR, were consistent with the plant-pathogen interaction under investigation and this further supports the suitability of dHPLC for cDNA-AFLP transcript profiling. Features and advantages of this new approach are discussed, evincing that it is an almost fully automatable and cost-effective solution for processing large numbers of samples and collecting differential genes involved in other biological processes and non-model plants.

Metallothioneins protect cytosolic creatine kinases against stress induced by nitrogen-based oxidants

The formation of intracellular nitrogen-based oxidants has important physiological and pathological consequences. CK (creatine kinase), which plays a key role in intracellular energy metabolism, is a main target of low concentrations of oxidative and nitrative stresses. In the present study, the interaction between cytosolic CKs [MM-CK (muscle-type CK) and BB-CK (brain-type CK)] and MTs [metallothioneins; hMT2A (human MT-IIA) and hMT3 (human MT-III)] were characterized by both in vitro and intact-cell assays. MTs could successfully protect the cytosolic CKs against inactivation induced by low concentrations of PN (peroxynitrite) and NO both in vitro and in hMT2A-overexpressing H9c2 cells and hMT3-knockdown U-87 MG cells. Under high PN concentrations, CK formed granule-like structures, and MTs were well co-localized in these aggregated granules. Further analysis indicated that the number of cells containing the CK aggregates negatively correlated with the expression levels of MTs. In vitro experiments indicated that MTs could effectively protect CKs against aggregation during refolding, suggesting that MT might function as a chaperone to assist CK re-activation. The findings of the present study provide direct evidence of the connection between the two well-characterized intracellular systems: the precisely balanced energy homoeostasis by CKs and the oxidative-stress response system using MTs.

Expression of a metallothionein A1 gene of Pisum sativum in white poplar enhances tolerance and accumulation of zinc and copper

Metallothioneins (MT) play an important role in heavy metal detoxification and homeostasis of intracellular metal ions in plant. In this study, two transgenic lines expressing MT type 2 gene (PsMT(A1)) from Pisum sativum, a regenerated non transformed line NT and clone AL22, selected as heavy metal tolerant, were characterized in presence of the heavy metals for the ability to accumulate zinc and copper and to activate antioxidative enzyme defences: superoxide dismutase, catalase, ascorbate peroxidase. The levels of expression of MT type 2 gene assessed by RT-qPCR confirmed the gene over-expression in transgenic lines and evidenced in NT and AL22 the up-regulation of gene transcription by zinc and copper. Transgenic poplar lines during heavy metal stress displayed increased ability to translocate and accumulate zinc and copper compared with NT and AL22. The antioxidant enzyme defence was differently activated in response to metals in the transgenic lines without a significant increase of ROS. These results suggested that PsMT(A1) could play a role in ROS scavenging leading to enhanced metal tolerance and increased zinc and copper sequestration in root and leaf.

Metallothionein-like gene from Cicer microphyllum is regulated by multiple abiotic stresses

Cicer microphyllum, a wild relative of cultivated chickpea, is a high altitude cold desert-adapted species distributed in western and trans-Himalayas. A complementary DNA (cDNA) encoding metallothionein-like protein has been identified from a cold-induced subtraction cDNA library from C. microphyllum. The sequence of the cloned metallothionein gene from C. microphyllum (GQ900702) contains 240-bp-long open reading frame and encodes predicted 79-amino acid protein of 7.9 kDa. Sequence analysis identified the motifs characteristic of type II metallothionein and designated as CmMet-2. Southern hybridization confirms a single copy of the CmMet-2 gene in C. microphyllum genome. In situ hybridization indicated spatial transcript regulation of CmMet-2 in root and aerial parts and also confirmed through real-time PCR-based quantitative transcript analysis. The data revealed a significantly low level of transcript in the aerial parts than the roots. Quantitative analysis using real-time PCR assay revealed induction of transcript in all parts of plants in response to cold stress at 4°C. The transcript abundance was found to increase exponentially with time course from 6 to 24 h after exposure. Further, regulation of transcript accumulation in response to abscisic acid application, polyethylene glycol (100 μM)-induced osmotic stress, or ZnSO(4) (1 μM) foliar spray indicated by Northern hybridization suggests the involvement of CmMet-2 in multiple stress response.

Comparative nephrotoxicity of Cisplatin and nedaplatin: mechanisms and histopathological characteristics

The antineoplastic platinum complexes cisplatin and its analogues are widely used in the chemotherapy of a variety of human malignancies, and are especially active against several types of cancers. Nedaplatin is a second-generation platinum complex with reduced nephrotoxicity. However, their use commonly causes nephrotoxicity due to a lack of tumor tissue selectivity. Several recent studies have provided significant insights into the molecular and histopathological events associated with nedaplatin nephrotoxicity. In this review, we summarize findings concerning the renal histopathology and molecular pathogenesis induced by antineoplastic platinum complexes, with a particular focus on the comparative nephrotoxicity of cisplatin and nedaplatin in rats.

Nanomaterial cytotoxicity is composition, size, and cell type dependent

Background

Despite intensive research efforts, reports of cellular responses to nanomaterials are often inconsistent and even contradictory. Additionally, relationships between the responding cell type and nanomaterial properties are not well understood. Using three model cell lines representing different physiological compartments and nanomaterials of different compositions and sizes, we have systematically investigated the influence of nanomaterial properties on the degrees and pathways of cytotoxicity. In this study, we selected nanomaterials of different compositions (TiO₂ and SiO₂ nanoparticles, and multi-wall carbon nanotubes [MWCNTs]) with differing size (MWCNTs of different diameters < 8 nm, 20-30 nm, > 50 nm; but same length 0.5-2 μm) to analyze the effects of composition and size on toxicity to 3T3 fibroblasts, RAW 264.7 macrophages, and telomerase-immortalized (hT) bronchiolar epithelial cells.

Results

Following characterization of nanomaterial properties in PBS and serum containing solutions, cells were exposed to nanomaterials of differing compositions and sizes, with cytotoxicity monitored through reduction in mitochondrial activity. In addition to cytotoxicity, the cellular response to nanomaterials was characterized by quantifying generation of reactive oxygen species, lysosomal membrane destabilization and mitochondrial permeability. The effect of these responses on cellular fate - apoptosis or necrosis - was then analyzed. Nanomaterial toxicity was variable based on exposed cell type and dependent on nanomaterial composition and size. In addition, nanomaterial exposure led to cell type dependent intracellular responses resulting in unique breakdown of cellular functions for each nanomaterial: cell combination.

Conclusions

Nanomaterials induce cell specific responses resulting in variable toxicity and subsequent cell fate based on the type of exposed cell. Our results indicate that the composition and size of nanomaterials as well as the target cell type are critical determinants of intracellular responses, degree of cytotoxicity and potential mechanisms of toxicity.

Protective effect of metallothionein on oxidative stress-induced DNA damage

Metallothioneins (MTs) are a family of low molecular weight proteins with a high cysteine and metal ion content. They are found in most cells and tissues and can be induced by a number of substances, including various forms of oxidative stress. MTs play a central role in essential trace element homeostasis and in metal detoxification. Because of their peculiar structure, characterized by a large content of thiol groups, MTs also act as a potent antioxidant by protecting against various injuries resulting from reactive oxygen (ROS) or nitrogen species (RNS). In this review, the involvement of MT in the protection of DNA against oxidative stress is discussed.

Antifibrotic activity of anthocyanidin delphinidin in carbon tetrachloride-induced hepatotoxicity in mice

The aim of this study was to investigate the hepatoprotective effects of anthocyanidin delphinidin in carbon tetrachloride (CCl(4))-induced liver fibrosis in mice. Male Balb/C mice were treated with CCl(4) dissolved in olive oil (20%, v/v, 2mL/kg) intraperitoneally (i.p.), twice a week for 7 weeks. Delphinidin was administered i.p. once daily for next 2 weeks, in doses of 10 and 25mg/kg of body weight. The CCl(4) control group has been observed for spontaneous reversion of fibrosis. CCl(4)-administration induced an elevation in serum transaminase and alkaline phosphatase levels and increased oxidative stress in the liver. Delphinidin has successfully attenuated oxidative stress, increased matrix metalloproteinase-9 and metallothionein I/II expression and restored hepatic architecture. Furthermore, the overexpression of tumor necrosis factor-alpha and transforming growth factor-beta1 has been withdrawn by delphinidin. Concomitantly, the expression of alpha-smooth muscle actin indicated returning of hepatic stellate cells (HSC) into inactive state. Our results suggest the therapeutic effects of delphinidin in CCl(4)-induced liver fibrosis by promoting extracellular matrix degradation, HSC inactivation and down-regulation of fibrogenic stimuli, with strong enhancement of hepatic regenerative capability.

Effects of exogenous metallothionein against thallium-induced oxidative stress in rat liver

Metallothionein (MT) is a low-molecular weight sulfur-rich protein that plays role in metal homeostasis/detoxification and radical scavenging. The following study investigated the ability of exogenous MT to protect against oxidative damage induced by thallium (TI) in rat liver. Male Wistar rats were divided into four groups; a control and three experimental groups. The control group received physiological saline. Group 1 animals were injected with thallium acetate intraperitoneally (i.p.) at a single dose of LD(50) (32 mg/kg). In group 2 and group 3, metallothionein I was administrated once at two different doses (1 or 2.5mg/kg i.p., respectively) 1h before TI intoxication. Levels of endogenous antioxidants, oxidative stress markers were measured and histopathological examinations were performed 4 days after TI administration. TI accumulation in liver decreased related to the dose of MT. Mostly all of the alterations in the levels antioxidants restored to normal levels in MT administrated animals. H(2)O(2) levels and lipid peroxidation decreased, integrity of hepatocytes and membranous structures inside the cells were preserved. The toxic effects of TI were modulated in MT administrated animals particularly at the dose of 2.5mg/kg. These findings suggest an active role of exogenous MT against TI-induced oxidative stress in rat liver.

Combined analysis of hypoxia-inducible factor 1 alpha and metallothionein indicates an aggressive subtype of colorectal carcinoma

PURPOSE

Hypoxia-inducible factor 1 (HIF-1) is a hypoxia-induced transcription factor that regulates gene expression in critical pathways involved in tumour growth and metastasis. Metallothionein (MT) is a group of small molecular weight cysteine-rich proteins with a broad variety of functions. The present study aimed to analyse the prognostic impact of HIF-1alpha and MT expression in colorectal cancer and to evaluate a possible link of combined HIF-1alpha and MT expression with colorectal cancer progression.

MATERIALS AND METHODS

We investigated the relationship of HIF-1alpha and MT with each other and clinicopathological parameters including proliferative activity (Ki67) and apoptosis (terminal desoxyribonucleotide transferase-mediated dUTP nick-end labelling) using immunohistochemistry.

RESULTS

HIF-1alpha expression was identified as an independent prognostic parameter in multivariate survival analysis and characterised an aggressive cancer phenotype. In addition, HIF-1alpha was significantly linked to an increased expression of MT.

CONCLUSIONS

HIF-1alpha expression qualified as an independent prognostic and characterised an aggressive cancer phenotype associated with an increased expression of MT. Our study suggests that MT can be added to the complex biological pathways induced by hypoxia in human cancer tissue.

Type 3 metallothioneins respond to water deficit in leaf and in the cambial zone of white poplar (Populus alba)

The involvement of metallothioneins (MTs) in response to plant water stress and recovery was assessed by analyzing gene expression in leaves and in the cambial zone of white poplar. One-year-old plants were submitted to two different watering regimes: irrigation was withheld for 9d and then resumed until day 17, or soil moisture was maintained to field capacity by irrigation during the experiment. Changes in leaves and stem water relations, gas exchange and CO(2) assimilation were recorded. The expression profiles of MT genes were analyzed in developing leaves and the cambial zone at maximum stress levels and after recovery and compared with the watered controls. Whole-plant water relations were significantly affected by water deprivation, though a complete recovery of plant water status was reached after resumption of watering. Withholding irrigation resulted in a significant decrease of leaf turgor potential and relative water content without a significant increase of the osmotic potential at full turgor. Similarly, stem water content decreased, leading to a marked increase of stem shrinkage, confirming that mild water stress affected primarily tissue water status. Following water depletion, the transcript analysis of MT genes revealed increased expression of type 3a and 3b MT genes in cambial tissues, and particularly in leaves. After water resumption, transcription decreased, suggesting that the changes in gene expression were related to water deficit. The results indicate that in leaves and, for the first time, in the cambial zone, type 3 MTs respond in a specific manner to changes in water status. These results are consistent with the regulatory cis-elements present in the 5' flanking region of type 3 MT genes.

Prion protein protects against zinc-mediated cytotoxicity by modifying intracellular exchangeable zinc and inducing metallothionein expression

PrPC contains several octapeptide repeats sequences toward the N-terminus which have binding affinity for divalent metals such as copper, zinc, nickel and manganese. However, the link between PrPC expression and zinc metabolism remains elusive. Here we studied the relationship between PrPC and zinc ions intracellular homeostasis using a cell line expressing a doxycycline-inducible PrPC gene. No significant difference in 65Zn2+ uptake was observed in cells expressing PrPC when compared with control cells. However, PrPC-expressing cells were more resistant to zinc-induced toxicity, suggesting an adaptative mechanism induced by PrPC. Using zinquin-ethyl-ester, a specific fluorophore for vesicular free zinc, we observed a significant re-localization of intracellular exchangeable zinc in vesicles after PrPC expression. Finally, we demonstrated that PrPC expression induces metallothionein (MT) expression, a zinc-upregulated zinc-binding protein. Taken together, these results suggest that PrPC modifies the intracellular localization of zinc rather than the cellular content and induces MT upregulation. These findings are of major importance since zinc deregulation is implicated in several neurodegenerative disorders. It is postulated that in prion diseases the conversion of PrPC to PrPSc may deregulate zinc homeostasis mediated by metallothionein.

Relationships between physiology, tissue contaminants, and biomarker responses in Atlantic cod (Gadus morhua L.)

It is generally assumed that there should be some relationship between tissue residues of contaminants and related biomarker responses in the same individual, with a possible additional modulation through physiological processes. The main basis for such assumptions originated from experimental studies, but it has been less easy to detect and quantify any such relationships in field-collected material. The aim of the current study was to clarify whether the responses of selected biomarkers (cytochrome P-4501A [CYP1A], delta-aminolevulinic acid dehydratase [ALA-D], metallothionein [MT]) could be correlated with physiological parameters and/or contaminant levels. Atlantic cod (Gadus morhua L.) were sampled over a decade at a number of locations along the Norwegian coast. The locations included both polluted and reference areas. In addition to contaminant-related responses (biomarkers), physiological characteristics were registered for each individual and the contaminant load determined. There were clear relationships between responses in all three biomarkers and tissue contaminants, but additional factors such as age or size and liver lipid or liver somatic index also contributed in multiple-regression models. The results indicated that responses in all three biomarkers reflected relevant, contaminant-related processes in the cod even though none of them provided a simple separation between polluted and pristine locations.

Detoxification mechanisms in shrimp: comparative approach between hydrothermal vent fields and estuarine environments

Hydrothermal vents are extreme deep-sea habitats that, due to their singular features, still intrigue scientific communities. Swift growth rates and profuse biomass of biological communities can be observed, despite of their inherently unstable physical-chemical and toxic conditions, indicating that organisms inhabiting this environment must be well adapted to these inhospitable conditions. The caridean shrimp, Chorocaris chacei, Mirocaris fortunata and Rimicaris exoculata, together with bathymodiolid mussels, dominate the vent fauna along the Mid-Atlantic Ridge (MAR). Crustacean species are widely used as biological indicators of environmental alterations, since they play a key ecological role as planktivorous grazers, epibenthic scavengers or as prey species. The biological consequences of the hydrothermal metal-rich environment in shrimp species are still largely unknown. Therefore, the aim of this study was the determination of the metal levels (Ag, Cd, Cu, Fe, Mn and Zn), metallothioneins (MT) and lipid peroxidation (LPO) in shrimp species collected in Rainbow, Lucky Strike and Menez-Gwen vent sites, in order to evaluate their different adaptation strategies toward metals when compared with two common coastal shrimp species (Palaemon elegans and Palaemonetes varians) from a fairly unpolluted estuarine system in south Portugal (Ria Formosa). Results show significant differences in metal concentrations, MT levels and lipid peroxidation between vent and coastal shrimp and also between shrimp species from the same site. This indicates that biochemical responses in both vent and coastal shrimp are affected not only by the environmental characteristics but also by inter-specific differences. Nevertheless, these responses apparently grant a successful adaptation for the survival in a metal-extreme environment.

Transcriptomic analysis reveals early signs of liver toxicity in female MRL +/+ mice exposed to the acylating chemicals dichloroacetyl chloride and dichloroacetic anhydride

Dichloroacetyl chloride (DCAC) is a reactive metabolite of trichloroethene (TCE). TCE and its metabolites have been implicated in the induction of organ-specific and systemic autoimmunity, in the acceleration of autoimmune responses, and in the development of liver toxicity and hepatocellular carcinoma. In humans, effects of environmental toxicants are often multifactorial and detected only after long-term exposure. Therefore, we developed a mouse model to determine mechanisms by which DCAC and related acylating agents affect the liver. Autoimmune-prone female MRL +/+ mice were injected intraperitoneally with 0.2 mmol/kg of DCAC or dichloroacetic anhydride (DCAA) in corn oil twice weekly for six weeks. No overt liver pathology was detectable. Using microarray gene expression analysis, we detected changes in the liver transcriptome consistent with inflammatory processes. Both acylating toxicants up-regulated the expression of acute phase response and inflammatory genes. Furthermore, metallothionein genes were strongly up-regulated, indicating effects of the toxicants on zinc ion homeostasis and stress responses. In addition, DCAC and DCAA induced the up-regulation of several genes indicative of tumorigenesis. Our data provide novel insight into early mechanisms for the induction of liver disease by acylating agents. The data also demonstrate the power of microarray analysis in detecting early changes in liver function following exposure to environmental toxicants.

Plant peptides and peptidomics

Extracellular plant peptides perform a large variety of functions, including signalling and defence. Intracellular peptides often have physiological functions or may merely be the products of general proteolysis. Plant peptides have been identified and, in part, functionally characterized through biochemical and genetic studies, which are lengthy and in some cases impractical. Peptidomics is a branch of proteomics that has been developed over the last 5 years, and has been used mainly to study neuropeptides in animals and the degradome of proteases. Peptidomics is a fast, efficient methodology that can detect minute and transient amounts of peptides and identify their post-translational modifications. This review describes known plant peptides and introduces the use of peptidomics for the detection of novel plant peptides.

Tris is a non-innocent buffer during intein-mediated protein cleavage

Fusion protein purification systems based on self-cleavable protein splicing elements are well established nowadays and have the advantage of producing recombinant proteins with their native amino acid composition while abolishing the need of an additional proteolytic cleavage step for removal of a purification tag. However, a potential disadvantage is the concomitant generation of reactive thioester intermediates during the protein self-splicing process, which are prone to undergo side reactions yielding undesired adducts. We followed the formation of these adducts as well as ways to avoid them with electrospray ionization mass spectrometry using one of our target proteins, Triticum aestivum (wheat) E(c)-1, a plant metallothionein with the ability to bind a total of six zinc or cadmium ions in the form of metal-thiolate clusters. Our investigations show that one of the most commonly used buffer substances, tris(hydroxymethyl)aminomethane (Tris), has to be applied with caution in combination with the described purification system, as it can itself react with the thioester intermediate forming a yet unreported stable adduct. This makes Tris a so called non-innocent buffer during the protein isolation procedure. Additionally, the results presented open up an interesting possibility to directly couple the one-step purification strategy with selective carboxy-terminal protein or peptide modification, e.g. the addition of fluorophors or PEGylation of peptides. Unrelated to the purification system used, we further observed a high amount of N-formylmethionine in the mass spectra when the protein of interest was expressed in cadmium-supplemented growth media.

Seasonal changes in mRNA encoding for cell stress markers in the oyster Crassostrea gigas exposed to radioactive discharges in their natural environment

The North Cotentin area (Normandy, France) hosts several nuclear facilities among which the AREVA reprocessing plant of La Hague is responsible for controlled discharges of liquid radioactive wastes into the marine environment. The resulting increase in radioactivity is very small compared to natural radioactivity. However, concerns about environment protection prompted the scientific community to focus on the effects of the chronic exposure to low concentrations of radionuclides in non-human biota. This study contributes to the evaluation of the possible impact of radioactive discharges on the oyster Crassostrea gigas in the field. Real-time polymerase chain reaction was used to quantify the expression levels of genes involved in cell stress in the oyster. They included members of the heat shock protein family (Hsp70, Hsc72, Hsp90), superoxide dismutase (SOD) and metallothionein (MT). Times series measurements were built from periodic samplings in the natural environment in order to characterize the natural variability as well as possible seasonal fluctuations. The genes studied exhibited a general seasonal expression pattern with a peak value in winter. The data inversely correlated with seawater temperature and the nature of the relationship between gene expression and temperature is discussed. In parallel, oysters were collected in four locations on the French shores, exposed or not to radioactive liquid wastes from the nuclear facilities hosted in the North Cotentin. The comparison of data obtained in the reference location on the Atlantic coast (not exposed) and data from oysters of the English Channel (exposed) gave no evidence for any statistical difference. However, because of the complexity of the natural environment, we cannot rule out the possibility that other parameters may have masked the impact of radioactive discharges. This dense set of data is a basis for the use of the expression levels of those genes as biomarkers to address the question of the possible effects of chronic exposure of the oyster to low concentrations of radionuclides in controlled laboratory experimental conditions.

Effects of dietary sulfur-containing amino acids on oxidative damage inrat liver caused byN-nitrosodimethylamine administration

Effects of dietary protein and S-containing amino acids on oxidative damage were investigated in rat liver. After feeding rats for 3 weeks from weaning, lower GSH levels and higher metallothionein (MT) levels were found in the liver of rats fed on a 10 % soyabean-protein-isolate (SPI)-based diet than those fed on a 10 % casein-based diet. After injection ofN-nitrosodimethylamine (NDMA) at 20 mg/kg body weight, increases in lipid peroxide, determined as thiobarbituric-acid reactive substances (TBARS), and γ-glutamyltransferase (GGT) activity in the liver were observed in the 10 % SPI diet group. By supplementing the 10 % SPI diet with 0·3 % cystine or methionine, GSH levels were increased, while MT levels were decreased, and elevation in TBARS levels after NDMA injection was diminished. On the other hand, increase in GGT activity could be prevented only by methionine supplement. On a 20 % SPI or casein diet, TBARS concentration and GGT activity were not altered after NDMA injection with concomitant increase in GSH levels and decrease in MT levels. These results indicate that sufficient amounts of methionine and cystine in a diet are important to protect the liver from oxidative damage after NDMA administration, and GSH plays a primary role in the cellular protective function when compared with MT.

ESTs from a wild Arachis species for gene discovery and marker development

BACKGROUND

Due to its origin, peanut has a very narrow genetic background. Wild relatives can be a source of genetic variability for cultivated peanut. In this study, the transcriptome of the wild species Arachis stenosperma accession V10309 was analyzed.

RESULTS

ESTs were produced from four cDNA libraries of RNAs extracted from leaves and roots of A. stenosperma. Randomly selected cDNA clones were sequenced to generate 8,785 ESTs, of which 6,264 (71.3%) had high quality, with 3,500 clusters: 963 contigs and 2537 singlets. Only 55.9% matched homologous sequences of known genes. ESTs were classified into 23 different categories according to putative protein functions. Numerous sequences related to disease resistance, drought tolerance and human health were identified. Two hundred and six microsatellites were found and markers have been developed for 188 of these. The microsatellite profile was analyzed and compared to other transcribed and genomic sequence data.

CONCLUSION

This is, to date, the first report on the analysis of transcriptome of a wild relative of peanut. The ESTs produced in this study are a valuable resource for gene discovery, the characterization of new wild alleles, and for marker development. The ESTs were released in the [GenBank:EH041934 to EH048197].

Induction of metallothionein in chick embryos as a mechanism of tolerance to platinum group metal exposure

Recent data show that platinum group metals (PGMs), primarily platinum (Pt), palladium (Pd) and rhodium (Rd), from automobile catalytic converters are being deposited in the environment. We investigated the PGM neurotoxicity and tolerance mechanism by induction of metallothionein (MT) in developing chick embryos. Chick embryos were injected on the 7th and 14th days of incubation with different concentrations of Pt and mixture of Pt, Pd and Rh (PGM mix) solutions. It is documented that induction of MT by zinc (Zn+2) protects against metal and non-metal hepatotoxicity. In this study the MT induction was examined through pretreatment of the two highest Pt(IV) exposure levels with exogenous Zn2+ on the 4th and 11th days of incubation. SDS-PAGE assay and digital image system were used to identify and quantify MT in homogenized brain and liver tissues. Quantitative analysis revealed an increase of MT in the 5 ppm Pt exposure as compared to controls. The 10 ppm Pt treatment was a lethal dose for exposed embryos. There was increased mortality at the 1.0 PGM mix level. The interaction of Pt, Pd and Rh in the mixture seems to favor metal accumulation and MT induction in the liver but not the brain. Pretreatment with exogenous Zn2+ increased chick survival. These results indicate that induction of MT plays a protective role against PGM toxicity. Metal analysis using atomic absorption spectrometer in graphite furnace mode (GFAAS) revealed PGM accumulation in chick embryo liver and brain tissues proportional to exposure concentration. Our results may imply that MT has an important role as a tolerance mechanism against PGM toxicity. The presence of Pt(IV) in brain tissue suggests that the undeveloped blood-brain barrier is permeable to PGMs. This raises concerns regarding the implication of these metals on neural injury.

Dietary phenolic antioxidants, caffeic acid and Trolox, protect rainbow trout gill cells from nitric oxide-induced apoptosis

Caffeic acid (CA) and Trolox are phenolic acids that have beneficial antioxidant effect, but the underlying mechanisms involved are not fully understood. The extent to which CA and Trolox protect against sodium nitroprusside (SNP)-induced oxidative cell injury was investigated in cultured rainbow trout gill cells. The cells exposed to SNP for 24 h displayed a dose-dependent leakage of lactate dehydrogenase (LDH) and decreased cell viability as indicated by the MTT assay (mitochondrial dehydrogenase activity). Both effects were prevented by treatment with 50 microM CA or Trolox. CA or Trolox, protected against SNP-induced caspase-3 activation and DNA fragmentation, indicating a reduction of apoptosis. Thus, the results indicate that SNP induced cell death is caspase-3 related apoptosis and the treatment with CA inhibited the apoptotic pathway. In addition, we studied the effect of CA and Trolox on expression of zinc-responsive antioxidant genes such as metallothioneins (MT), glutathione-S-transferase (GST Class pi) and glucose-6-phosphate dehydrogenase (G6PD) in cultured gill cells. CA, 100 microM, increased accumulation of mRNA for MTA, MTB, GST and G6PD in cells. Thus, in addition to its ability to sequester free radicals, CA may protect against oxidative stress through expression of zinc-induced antioxidant proteins. Because of these properties we suggest that CA could be a beneficial additive to fish feeds in aquaculture.

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.