Identification of members of the annexin family in the detergent-insoluble fraction of rat Morris hepatoma plasma membranes

For proteomic analysis, plasma membranes of rat hepatocellular carcinoma Morris hepatoma 7777 were selectively solubilized according to the previously developed method [D. Josic, K. Zeilinger, Methods Enzymol. 271 (1996) 113-134]. If the Triton X100 insoluble pellet is subsequently extracted, several proteins can be solubilized. These proteins can be classified in two groups according to their molecular size. The proteins with apparent molecular weights in SDS-PAGE between 70 and 75 kDa belong to the first group. Smaller proteins, with apparent molecular weights between 30 and 45 kDa, are members of the second group. The main protein of higher molecular weight was also found in the Triton X100 insoluble extract from normal rat liver plasma membranes. This protein was identified as Annexin A6. The proteins from the second group are practically absent in the Triton X100 insoluble extract from rat liver. These proteins are present in relatively high concentrations in plasma membranes of Morris hepatoma 7777. Both groups of detergent-insoluble proteins from Morris hepatoma 7777 were further analyzed with SELDI-TOF and LC electrospray ionization mass spectrometry. From the first group, Annexin A6, together with two other integral plasma membrane proteins, was identified. In the second group of proteins with apparent molecular weights between 30 and 45kDa, further members of the annexin family, Annexins A1, A2, A4, A5 and A7 were identified. The possible role of these low molecular size annexins as potential cancer biomarkers is discussed.     

Influence of oxidative injury and monitoring of blood plasma by DSC on breast cancer patients

Damage caused by oxidative stress is involved in many types of diseases, including breast cancer. Our aim was to detect the oxidative stress parameters and blood plasma changes with differential scanning calorimetry (DSC) in breast cancer patients. The study included 40 adult breast cancer women who were grouped according to tumor diameter, regional lymph node metastases, proliferative activity, receptor status and postoperative chemotherapy. To monitor oxidative stress, malondialdehyde, oxygen free radicals (OFRs), activity of myeloperoxidase (MPO), superoxide dismutase (SOD) and catalase (CAT) were measured. Denaturation of plasma components was detected in Setaram Micro DSC-II calorimeter. The total production of OFRs, the MPO activity and lipidperoxidation were significantly increased in each breast cancer patients considering the tumor size, the metastatic lymph nodes, the proliferation activity and receptor status compared with healthy controls (p < 0.05). These pro-oxidants were slightly elevated without chemotherapy, but their values were increased significantly in chemotherapy-receiving group. The activity of SOD and CAT was significantly decreased in all groups, and in regard to the chemotherapy, they were changed significantly parallel to the severity of disease. Regarding to both the increased tumor diameter and the increased number of affected lymph nodes, DSC measurements showed a strong relationship between the maximum excess heat capacity (C_pmax) of the blood plasma and the severity of disease. The study demonstrated that oxidative stress is implicated in breast carcinoma and chemotherapy aggravates these changes which confirmed the plasma DSC measurements also.     

Superoxide dismutase activity in some strains of lactobacilli: induction by manganese

Dialyzed cell-free extract of lactobacilli was found to contain superoxide dismutase activity by using a test system in which superoxide ion is generated by xanthine oxidase. The specific activities of Lactobacillus acidophilus ATCC 4356, Lactobacillus murinus ATCC 35020, Lactobacillus acidophilus CRL 358, Lactobacillus plantarum ATCC 8014, Lactobacillus casei CRL 431, Lactobacillus plantarum CRL 353, Lactobacillus fermentum ATCC 9338, Lactobacillus buchneri NCDO 110, and Lactobacillus fermentum CRL 251 were between 0.06 and 0.43 U/mg protein. The presence of superoxide dismutase activity was demonstrated when the strains were grown in media containing Mn2+ ions. Superoxide dismutase of lactobacilli may be an Mn enzyme since it was not inhibited by either cyanide or azide ions. However, the cell-free extract of Lactobacillus murinus ATCC 35020 contains superoxide dismutase activity sensitive to both ions.     

Protein expression patterns associated with advanced stage ovarian cancer

This is a comparative proteomic study on biopsies from patients with ovarian cancer to identify potential diagnostic/prognostic biomarkers in both healthy and tumor tissue, interstitial fluid (normal interstitial fluid and tumoral interstitial fluid and peritoneal effusion. Protein expression/identification was evaluated by 2-DE and MS analysis: six proteins showed differential expression in tumoral interstitial fluid and tumor tissue compared to normal interstitial fluid and healthy tissue: five were found to be downregulated and identified as galectin 3, glutathione S-transferase A-2, retinol binding protein 1, phosphatidylethanolamine-binding protein and annexin 5, while the calgranulin, was significantly upregulated in all pathological samples, including the ascitic fluid. Validation of S100A8 overexpression in carcinoma tissue was obtained by immunohistochemistry. To our knowledge, this is the first study to report an over-expression of calgranulin by 2-DE associated with MS/MS analysis on surgical biopsy. The reduced expression of galectin 3 and retinol binding protein 1 in cystic fluid and serum of patients with early stage disease is confirmed in this study. The results highlight alterations in proteins that control cell-cycle progression and apoptosis, as well as factors that modulate the activity of signal transduction pathways. Moreover, this study suggests that calgranulin expression may be used as a diagnostic and/or prognostic biomarker.     

Mass Spectrometric Characterization of Protein Structure Details Refines the Proteome Signature for Invasive Ductal Breast Carcinoma

Early diagnosis as well as individualized therapies are necessary to reduce the mortality of breast cancer, and personalized patient care strategies rely on novel prognostic or predictive factors. In this study, with six breast cancer patients, 2D gel analysis was applied for studying protein expression differences in order to distinguish invasive ductal breast carcinoma, the most frequent breast tumor subtype, from control samples. In total, 1203 protein spots were assembled in a 2D reference gel. Differentially abundant spots were subjected to peptide mass fingerprinting for protein identification. Twenty proteins with their corresponding 38 differentially expressed 2D gel spots were contained in our previously reported proteome signature, suggesting that distinct protein forms were contributing. In-depth MS/MS measurements enabled analyses of protein structure details of selected proteins. In protein spots that significantly contributed to our signature, we found that glyceraldehyde-3-phosphate dehydrogenase was N-terminally truncated, pyruvate kinase M2 and nucleoside diphosphate kinase A but not other isoforms of these proteins were of importance, and nucleophosmin phosphorylation at serine residues 106 and 125 were clearly identified. Principle component analysis and hierarchical clustering with normalized quantitative data from the 38 spots resulted in accurate separation of tumor from control samples. Thus, separation of tissue samples as in our initial proteome signature could be confirmed even with a different proteome analysis platform. In addition, detailed protein structure investigations enabled refining our proteome signature for invasive ductal breast carcinoma, opening the way to structure-/function studies with respect to disease processes and/or therapeutic intervention.     

Anti‐proliferative activity of newly synthesized Cd(II), Cu(II), Zn(II),Ni(II), Co(II), VO(II), and Mn(II) complexes of 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide on three human cancer cells

Thiosemicarbazone ligand, 2‐((4,9‐dimethoxy‐5‐oxo‐5H‐furo[3,2‐g]chromen‐6‐yl)methylene) hydrazinecarbothioamide and its Cd(II), Cu(II), Zn(II), Ni(II), Co(II), VO(II), and Mn(II) complexes have been prepared and characterized by various spectroscopic and analytical techniques. Complexes molar conductance measurements displayed that all complexes (2–8) are non‐electrolyte. With general composition [M(H₃L)(CH₃COO)₂H₂O].nH₂O, where M = Cd(II), Cu(II), Zn(II), Ni(II), Co(II) and Mn(II) while complex (8) has [VO(H₃L)(SO₄)H₂O].2H₂O formula. Based on analytical and spectral measurements, the octahedral or distorted octahedral geometries suggested for complexes. Ligand and complexes anti‐proliferative activities were assessed against three various human tumor cell lines including breast cancer (MCF‐7), liver cancer (HepG2) and lung cancer (A549) using SRB fluorometric assay and cis‐platin as positive control. The anti‐proliferative activity result indicated that the ligand and its complexes have considerable anti‐proliferative activity analogous to that of ordinarily utilized anti‐cancer drug (cis‐platin). They do their anti‐cancer activities by modifying free radical's generation via raising the superoxide dismutase activity and depletion of intracellular reduced glutathione level, catalase, glutathione peroxidase activities, escorted by highly generation of hydrogen peroxide, nitric oxide and other free radicals leading to tumor cells death, as monitoring by decreasing the protein and nucleic acids synthesis.     

The Voltammetric Behavior of Superoxide Dismutase/Catalase Mimics

The voltammetric behavior of the superoxide dismutase/catalase mimics [(N,N′‐bis(salicylidene)ethylenediamine)Mn(III)]Cl (or salenMn(III) chloride) 1 and [(N,N′‐bis(3‐methoxysalicylidene)ethylenediamine)Mn(III)]Cl (or 3,3′‐methoxysalenMn(III) chloride) 2 in acetonitrile is described. Both compounds show quasi‐reversible one‐electron reductions to the Mn(II) compound. Electroanalytical techniques are used to follow the reaction between superoxide and 1 and 2 and it is shown that it is the reduced Mn(II) compounds which scavenge superoxide. It is also shown that both compounds electrocatalytically generate superoxide in the presence of dissolved dioxygen. The rate constant for this reaction was determined for both compounds using microelectrode steady state voltammetry. A general reaction scheme for interactions between these compounds and both dissolved dioxygen and superoxide is proposed.     

Exploration of Potential Tumor Markers for Lung Adenocarcinomas by Two‐Dimensional Gel Electrophoresis Coupled with Nano‐LC/MS/MS

To explore the potential tumor markers for lung adenocarcinoma, two‐dimensional gel electrophoresis (2DE) coupled with nano‐LC/MS/MS was used to analyze the differentially expressed proteins in 10 surgical resected lung adenocarcinoma tissues. 16 proteins were significantly different between the cancer tissue and adjacent normal tissue. Galectin‐1, peroxiredoxin II (Prx II), proapolipoprotein, glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), aldolase A, enolase 1, neuropolypeptide h3, Prx V, cyclophilin A, vimentin, protein disulfide isomerase (PDI), tropomyosin 3 (TPM 3), glutathione S‐transferase Pi (GST‐Pi), manganese superoxide dismutase (MnSOD), and cofilin 1 were up‐regulated in the cancer tissue. On the other hand, profilin was down‐regulated in the cancer tissue. Among these proteins, six proteins were validated by Western blot analysis. The identified proteins contributing to the spectrum of cancer progression may be used as potential diagnostic biomarkers for lung adenocarcinomas.     

Combinatorially Designed Lipid‐like Nanoparticles for Intracellular Delivery of Cytotoxic Protein for Cancer Therapy

An efficient and safe method to deliver active proteins into the cytosol of targeted cells is highly desirable to advance protein‐based therapeutics. A novel protein delivery platform has been created by combinatorial design of cationic lipid‐like materials (termed “lipidoids”), coupled with a reversible chemical protein engineering approach. Using ribonuclease A (RNase A) and saporin as two representative cytotoxic proteins, the combinatorial lipidoids efficiently deliver proteins into cancer cells and inhibit cell proliferation. A study of the structure–function relationship reveals that the electrostatic and hydrophobic interactions between the lipidoids and the protein play a vital role in the formation of protein–lipidoid nanocomplexes and intracellular delivery. A representative lipidoid (EC16‐1) protein nanoparticle formulation inhibits cell proliferation in vitro and suppresses tumor growth in a murine breast cancer model.     

Annexin II, a novel HSP27-interacted protein, is involved in resistance to UVC-induced cell death in human APr-1 cells

Heat shock protein 27 (HSP27) is implicated in diverse biologic functions as a molecular chaperone. We found that HSP27 is involved in the protection of human cells against UVC lethality. To elucidate the molecular mechanisms underlying UVC resistance, we searched for HSP27-interacted proteins related to resistance in UVC-resistant human cells, APr-1. Three candidates for HSP27-interacted proteins were found from cell lysates using an affinity column coupled with GST-fused HSP27 protein. Interaction between HSP27 and two candidates, annexin II and HSP70, was confirmed by immunoprecipitation analysis. After UVC irradiation, the amount of the complex of HSP27 and annexin II decreased in the postnuclear fraction, while it increased in the nuclear fraction. Cells transfected with annexin II-siRNA were more susceptible to UVC lethality. These results suggest that annexin II is a novel HSP27-interacted protein which is involved in UVC resistance in human cells, at least those tested here.     

Proteomics Approach of Rapamycin Anti-Tumoral Effect on Primary and Metastatic Canine Mammary Tumor Cells In Vitro

Rapamycin is an antifungal drug with antitumor activity and acts inhibiting the mTOR complex. Due to drug antitumor potential, the aim of this study was to evaluate its effect on a preclinical model of primary mammary gland tumors and their metastases from female dogs. Four cell lines from our cell bank, two from primary canine mammary tumors (UNESP-CM1, UNESP-CM60) and two metastases (UNESP-MM1, and UNESP-MM4) were cultured in vitro and investigated for rapamycin IC₅₀. Then, cell lines were treated with rapamycin IC₅₀ dose and mRNA and protein were extracted in treated and non-treated cells to perform AKT, mTOR, PTEN and 4EBP1 gene expression and global proteomics by mass spectrometry. MTT assay demonstrated rapamycin IC₅₀ dose for all different tumor cells between 2 and 10 μM. RT-qPCR from cultured cells, control versus treated group and primary tumor cells versus metastatic tumor cells, did not shown statistical differences. In proteomics were found 273 proteins in all groups, and after data normalization 49 and 92 proteins were used for statistical analysis for comparisons between control versus rapamycin treatment groups, and metastasis versus primary tumor versus metastasis rapamycin versus primary tumor rapamycin, respectively. Considering the two statistical analysis, four proteins, phosphoglycerate mutase, malate dehydrogenase, l-lactate dehydrogenase and nucleolin were found in decreased abundance in the rapamycin group and they are related with cellular metabolic processes and enhanced tumor malignant behavior. Two proteins, dihydrolipoamide dehydrogenase and superoxide dismutase, also related with metabolic processes, were found in higher abundance in rapamycin group and are associated with apoptosis. The results suggested that rapamycin was able to inhibit cell growth of mammary gland tumor and metastatic tumors cells in vitro, however, concentrations needed to reach the IC₅₀ were higher when compared to other studies.     

Effects of a Single Exposure to UVB Radiation on the Activities and Protein Levels of Copper-Zinc and Manganese Superoxide Dismutase in Cultured Human Keratinocytes

Abstract— Ultraviolet B irradiation has been believed to decrease or impair the activity of reactive oxygen species (ROS) scavenging enzymes such as superoxide dismutase (SOD) in the skin. It has been recently reported that two isozymes of SOD, namely copper-zinc SOD (Cu-Zn SOD) and manganese SOD (Mn SOD), exist in mammalian cells and that the two enzymes play different roles in living systems. The aim of this study was to investigate changes in SOD activities and protein levels in cultured human keratinocytes after acute UVB irradiation. In addition, the protein levels of Cu-Zn SOD and Mn SOD were quantified separately. A single exposure to UVB irradiation produced an increase in SOD activity and protein level that peaked immediately after UVB irradiation, after which a decline was observed, with subsequent recovery to baseline levels 24 h after irradiation. In individual assays of Mn SOD and Cu-Zn SOD, the amount of Mn SOD protein decreased and then gradually recovered 24 h after irradiation. In contrast, the amount of Cu-Zn SOD protein increased immediately after UVB irradiation, and then gradually declined. To evaluate the mechanisms of these changes, we examined the effects of the cytokines, interleukin-1α (IL-1α) and tumor necrosis factor-α (TNF-α), which can be secreted from keratinocytes after UVB irradiation, on the SOD activity and protein levels in keratinocytes. Interleukin-la and TNF-α enhanced both the SOD activity and protein level of Mn SOD, while these cytokines had no effect on Cu-Zn SOD protein levels in cultured human keratinocytes after incubation for 24 h. Furthermore, when neutralizing antibodies against IL-1α and TNF-α were added separately or together to the culture medium before UVB irradiation, the recovery of total SOD activity and Mn SOD protein level were markedly inhibited 24 h after irradiation. Our results suggest that significant increases in SOD activity and protein level occur as a cutaneous antioxidant defense mechanism that protects against the cytotoxicity as a result of UVB irradiation, and that this increase in SOD is attributed to Cu-Zn SOD. The Cu-Zn SOD and Mn SOD protein levels changed in a different manner after UVB irradiation. The former may participate in an early phase and the latter in a late phase defense mechanism directed against oxidant cytotoxicity through UVB irradiation. In addition, the recovery of Mn SOD to baseline levels 24 h after UVB irradiation seems to be mediated through cytokines such as IL-1α and TNF-α, which are secreted from keratinocytes.     

Expression patterns of antioxidant proteins in brains of patients with sporadic Creutzfeldt-Jacob disease

Using two-dimensional gel electrophoresis (2-DE) and Western blot analysis, we were able to identify and quantify six antioxidant proteins, peroxiredoxin (Prx) I, Prx II, Prx III, 1-Cys Prx, putative peroxisomal antioxidant enzyme (PLP), and mitochondrial Mn superoxide dismutase (Mn-SOD) in two individual brain regions, cerebellum and frontal cortex of patients with sporadic Creutzfeldt-Jacob (sCJD). Among six antioxidant proteins, 1-Cys Prx showed significant increase (P > 0.05) in sCJD frontal cortex whereas Prx I was decreased (P > 0.01). In cerebellum, levels of all antioxidant proteins studied were comparable to those of controls. Our findings provide evidence for the link between aberrant expression of antioxidant proteins, 1-Cys Prx and Prx I and CJD neuropathogenesis and we discuss the neuropathological meaning of these dysregulated antioxidant proteins in sCJD brain.     

Proteomic investigation of anti-tumor activities exerted by sinularin against A2058 melanoma cells

The extracts from soft corals have been increasingly investigated for biomedical and therapeutic purposes. The aim of this study is to examine and analyze the anti-tumor effects of the genus Sinularia extract sinularin on A2058 melanoma cells using MTT assay, cell migration assay, wound healing assay, flow cytometric analysis, and proteomic analysis. Sinularin dose-dependently (1-5 μg/mL) inhibited melanoma cell proliferation while the treatment at identical concentrations suppressed cell migration. Sinularin dose-dependently enhanced apoptotic melanoma cells and caused tumor cell accumulation at G2/M phase, indicating that sinularin exerts apoptosis-induced and cell cycle-delayed activities in A2058 melanoma cells. Comparative proteomic analysis was conducted to investigate the effects of sinularin at the molecular level by comparison between the protein profiling of melanoma cells treated with sinularin and without the treatment. Thirty-five differential proteins (13 upregulated and 22 downregulated) concerning the treatment were identified by liquid chromatography-tandem mass spectrometry. Proteomic data and Western blot displayed the levels of several tumor inhibitory or apoptosis-associated proteins including annexin A1, voltage-dependent anion-selective channel protein 1 and prohibitin (upregulated), heat shock protein 60, heat shock protein beta-1, and peroxiredoxin-2 (downregulated) in A2058 melanoma cells exposed to sinularin. Increased expression of p53, cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, p21, and Bax and decreased expression of Bcl-2 in sinularin-treated melanoma cells suggest that the anti-tumor activities of sinularin against melanoma cells are particularly correlated with these pro-apoptotic factors. These data provide important information for the mechanisms of anti-tumor effects of sinularin on melanoma cells and may be helpful for drug development and progression monitoring of human melanoma.     

Determination of Cu, Fe, Mn, and Zn in blood fractions by SEC-HPLC-ICP-AES coupling

The binding of Cu, Fe, Mn, and Zn to proteins in blood and in blood fractions was investigated, since their interactions in free radical metabolism in humans is of great interest. An HPLC-ICP-AES technique was developed allowing adequate separation of metalloproteins and of inorganic and organic metal species. For the separation of metalloproteins in erythrocytes and blood plasma a Merck Superformance Fractogel EMD BioSEC 650 (S) column was used. Size exclusion chromatography (SEC)-HPLC was hyphenated to ICP-AES both on-line and off-line for the detection of trace elements in the fractions resulting from HPLC separations. HPLC parameters, pH, temperature, flow rate and salt concentration were optimized for the protein separation and the optimal conditions were applied for the hyphenation to the ICP-AES detector. The separation column was calibrated with five standard proteins. For the element determination by ICP-AES a line selection with respect to the sensitivity was performed. Three different methods were used for the determination of trace elements in blood: direct determinations, on-line and off-line SEC-HPLC-ICP-AES measurements. For the optimizing experiments blood samples of one female subject were used. The direct determination by ICP-AES of the elements was performed in blood and blood fractions of ten different subjects to obtain the average concentration ranges. From the results the identification of the protein Cu/Zn superoxide dismutase in erythrocytes was possible. The LOD were 0.03 microgram mL-1 for Cu, 0.026 microgram mL-1 for Fe, 0.8 ng mL-1 for Mn, and 0.09 microgram mL-1 for Zn in a synthetic blood matrix.     

New conjugates of β-cyclodextrin with manganese(III) salophen and porphyrin complexes as antioxidant systems

Oxidative stress is the hallmark of several pathologies like arthritis, hypertension and many neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. In this scenario, antioxidant compounds can play a pivotal role in treating these severe pathologies. The synthesis of molecules able to mimic physiologically-relevant proteins is nowadays of particular interest. Several transition metal complexes, especially manganese(III) complexes with porphyrin and salen-type ligands, have been reported to be superoxide scavengers. Here we report the synthesis and spectroscopic characterization of manganese(III) complexes of 5[4-(6-O-β-cyclodextrin)-phenyl],10,15,20-tri(4-hydroxyphenyl)-porphyrin and of 6(A)-deoxy-6(A)[(S-cysteamidobenzoyl(3,4-diamino)-N,N'-bis(salicylidene))]-β-cyclodextrin. The superoxide dismutase activity of the metal complexes was investigated by indirect methods. The catalase and peroxidase activities were tested using ABTS assays.     

Temperature-dependent coordination in E. coli manganese superoxide dismutase

Two different temperature dependences of the manganese(II) high-field electron paramagnetic resonance spectrum of manganese superoxide dismutase from E. coli were observed. In the 25-200 K range, the zero-field interaction steadily decreased with increasing temperature. This was likely due to the thermal expansion of the protein. From these results, it was possible to deduce an approximately r(-)(2.5) dependence of Mn(II) zero-field interaction on ligand-metal distance. At temperatures above 240 K, a distinct six-line component was detected, the amplitude of which decreased with increasing temperature. On the basis of similarities to the six-line spectrum observed for the azide-complexed E. coli manganese superoxide dismutase, the newly detected six-line spectrum was assigned to a hexacoordinate Mn(II) center resulting from the coordination of a nearby water molecule to the normally five-coordinate center. The changes in enthalpy and entropy characterizing the hexacoordinate-pentacoordinate equilibrium in the 240-268 K range were -5 kcal/mol and -24 cal/mol.K, respectively. The structural implications of the zero-field parameters of the newly found hexacoordinate form in comparison to those of the Mn(II) centers in concanavalin-A and manganese-containing R. spheroides photosynthetic reaction centers and the values predicted by the superposition model are discussed.     

The effect of miR-7 on behavior and global protein expression in glioma cell lines

Malignant glioma is a common cancer of the nervous system. Despite recent research efforts in cancer therapy, the prognosis of patients with malignant glioma has remained dismal. MicroRNAs are noncoding RNAs that inhibit the expression of their targets in a sequence-specific manner, and a few have been shown to act as oncogenes or tumor suppressors. Here, we aimed at exploring the precise biological role of microRNA-7 (miR-7) and the global protein changes in glioma cell lines transiently transfected with miR-7. Transfection of miR-7 into glioma cell lines causes inhibition of cell migration and invasion and suppression of tumorigenesis. Moreover, ectopic expression of miR-7 inhibits lung metastases of glioma in vivo. Among 65 protein spots with differential expression separated by 2-DE, 37 proteins were successfully identified by MS/MS analysis. Of those, the 25 downregulated proteins, which include 14-3-3ζ, eukaryotic translation initiation factor 5A (EIF5A), and annexin A4, may be downstream targets of miR-7, a finding that could elucidate some aspects of the behavior of glioma cells at the protein level. In conclusion, the absence of miR-7 function could cause downstream molecules to switch on or off, resulting in glioma development, invasion, and metastases. MiR-7-based gene treatment may be a novel anti-invasion therapeutic strategy for malignant glioma.     

Protective Effect of Hydroxytyrosol Against Oxidative Stress Mediated by Arsenic-Induced Neurotoxicity in Rats

The present study reports beneficial effect of hydroxytyrosol (HT) against arsenic (As)-induced oxidative stress in the rat brain. Rats were orally administered with sodium arsenite dissolved in distilled water (25 ppm, by oral gavage) for 8 weeks or HT (10 mg/kg b. wt.) in combination with As. Results showed increase in protein oxidation and lipid peroxidation, while catalase and superoxide dismutase (SOD) activities as well as GSH content were decreased after As exposure in rat brain. Fourier transform infrared analysis showed significant alteration in peak area values that also validated the oxidative damage to lipids and proteins. In addition, As exposure caused increase in protein expression of caspase-3 and Bax, while Bcl-2 expression was downregulated resulting in translocation of cytochrome c from mitochondria to cytosol. Treatment of HT with As reversed protein oxidation, lipid peroxidation, and increased GSH content as well as catalase and SOD activities. Administration of HT also prevented translocation of cytochrome c from mitochondria and increased mitochondria/cytosol ratio of cytochrome c. Hence, treatment of HT with As improved antioxidant system and efficiently lowered the generation of oxidative stress in rat brain.