Role of alpha-tocopherol on antioxidant status in liver, lung and kidney of PCB exposed male albino rats

Modulation in growth, oxidative stress, photosynthesis, and morphology reveals higher toxicity of alpha-cypermethrin than chlorpyrifos towards a non-target green alga at high doses

Considering the frequent detection of pesticides in the aquatic environment, the ecotoxicological effects of Chlorpyrifos (CHP), an organophosphate, and alpha-cypermethrin (ACM), a pyrethroid, on freshwater microalgae were compared for the first time in this study. High concentrations of both CHP and ACM significantly suppressed the growth of test microalga Graesiella emersonii (p < 0.05). The 96-h EC50 of CHP and ACM were 54.42 mg L-1 and 29.40 mg L-1, respectively. Sub-inhibitory doses of both pesticides increased ROS formation in a concentration-dependent manner, which was accompanied by changes in antioxidant enzymes activities, lipid peroxidation, and variations in photosynthetic pigment concentration. Furthermore, both pesticides influenced photosystem II performance, oxygen-evolving complex efficiency and, intracellular ATP levels. Scanning electron microscopy analysis revealed that high concentrations of both CHP and ACM caused considerable morphological changes in the microalga. In comparison, CHP was more toxic than ACM at low concentrations, whereas ACM was more toxic at high concentrations.

Antioxidant and Anti-Inflammatory Properties of Phytochemicals Found in the Yucca Genus

The Yucca genus encompasses about 50 species native to North America. Species within the Yucca genus have been used in traditional medicine to treat pathologies related to inflammation. Despite its historical use and the popular notion of its antioxidant and anti-inflammatory properties, there is a limited amount of research on this genus. To better understand these properties, this work aimed to analyze phytochemical composition through documentary research. This will provide a better understanding of the molecules and the mechanisms of action that confer such antioxidant and anti-inflammatory properties. About 92 phytochemicals present within the genus have reported antioxidant or anti-inflammatory effects. It has been suggested that the antioxidant and anti-inflammatory properties are mainly generated through its free radical scavenging activity, the inhibition of arachidonic acid metabolism, the decrease in TNF-α (Tumor necrosis factor-α), IL-6 (Interleukin-6), iNOS (Inducible nitric oxide synthase), and IL-1β (Interleukin 1β) concentration, the increase of GPx (Glutathione peroxidase), CAT (Catalase), and SOD (Superoxide dismutase) concentration, and the inhibition of the MAPK (Mitogen-Activated Protein Kinase), and NF-κB (Nuclear factor kappa B), and the activation of the Nrf2 (Nuclear factor erythroid 2-related factor) signaling pathway. These studies provide evidence of its use in traditional medicine against pathologies related to inflammation. However, more models and studies are needed to properly understand the activity of most plants within the genus, its potency, and the feasibility of its use to help manage or treat chronic inflammation.

New insight into the perplexing toxic features of PCBs: A study of nephrotoxicity in an animal model

The present study investigated the effects of PCBs on the rat kidneys with attention given to the determination critical effect dose (CED) using the Benchmark dose (BMD) approach. Male albino Wistar rats (7 animals per group) were given by oral gavage Aroclor 1254 dissolved in corn oil at doses of 0.0, 0.5, 1, 2, 4, 8, or 16 mg/kg b.w./day for 28 days. The PCB nephrotoxicity was manifested by a dose-dependent changes in serum urea levels. The study has also revealed PCB-induced oxidative stress induction in kidneys. The observed nephrotoxic effects can be partly explained by oxidative damage of lipids and proteins in the kidneys due to observed reduced CuZnSOD activity and disturbances in antioxidant protection. Аll the renal oxidative stress parameters showed dependence on PCB oral doses as well as internal, measure kidney PCB levels. Calculated BMDL values were lower than estimated no observed adverse effect levels (NOAEL) based on the study, suggesting the importance of BMD approach use in future risk assessment.

Bioaccumulation, Metabolism, and Biomarker Responses in Hyriopsis cumingii Exposed to 4-Mono-Chlorinated Dibenzothiophene

Polychlorinated dibenzothiophenes (PCDTs) are sulfur analogues of polychlorinated dibenzofurans with prevalent occurrence in aquatic environments and potential ecological risks. However, data on the behavior and toxicity of PCDTs in aquatic organisms remain scarce. In the present study, the bioaccumulation, metabolism, and oxidative damage of 4-mono-chlorinated dibenzothiophene (4-mono-CDT) in freshwater mussel (Hyriopsis cumingii) were investigated after exposure to 4-mono-CDT in semistatic water. The uptake rates, depuration rates, half-lives, and bioconcentration factors of 4-mono-CDT in hepatopancreas, gill, and muscle tissues ranged from 0.492 to 1.652 L d^-1  g^-1 dry weight, from 0.117 to 0.308 d^-1 , from 2.250 to 5.924 d, and from 2.903 to 8.045 × 10³  L kg^-1 dry weight, respectively. A dechlorinated metabolite (dibenzothiophene) was detected in hepatopancreas tissue, indicating that dechlorination was the main metabolic pathway of 4-mono-CDT. As the exposure time increased, the activities of superoxide dismutase, catalase, and glutathione peroxidase were induced or inhibited in the different experimental groups. The malondialdehyde content increased with increasing 4-mono-CDT dose and exposure time. A higher concentration of 4-mono-CDT corresponded to a greater integrated biomarker response in each tissue and greater oxidative damage. The antioxidant enzymes in hepatopancreas were more sensitive to 4-mono-CDT than those in gill. The results provide useful information on the behavior and ecotoxicity of PCDTs in freshwater mussels. Environ Toxicol Chem 2021;40:1873-1882. © 2021 SETAC.

Renal changes and apoptosis caused by subacute exposure to Aroclor 1254 in selenium-deficient and selenium-supplemented rats

Aroclor 1254 (A1254), a mixture of polychlorinated biphenyls, exerts hepatic, renal, and reproductive toxicity in rodents. This study aimed to determine a protective role of selenium on histopathological changes, oxidative stress, and apoptosis caused by A1254 in rat kidney. It included a control group, which received regular diet containing 0.15 mg/kg Se (C), a Se-supplemented group (SeS) receiving 1 mg/kg Se, a Se-deficient group (SeD) receiving Se-deficient diet of ≤0.05 mg/kg Se, an A1254-treated group (A) receiving 10 mg/kg of Aroclor 1254 and regular diet, an A1254-treated group receiving Se-supplementation (ASeS), and an A1254-treated group receiving Se-deficient diet (ASeD). Treatments lasted 15 days. After 24 h of the last dose of A1254, the animals were decapitated under anaesthesia and their renal antioxidant enzyme activities, lipid peroxidation (LP), glutathione, protein oxidation, and total antioxidant capacity levels measured. Histopathological changes were evaluated by light and electron microscopy. Apoptosis was detected with the TUNEL assay. Kidney weights, CAT activities, and GSH levels decreased significantly in all A1254-treated groups. Renal atrophic changes and higher apoptotic cell counts were observed in the A and ASeD groups. Both groups also showed a significant drop in GPx1 activities (A – 34.92 % and ASeD – 86.46 %) and rise in LP (A – 30.45 % and ASeD – 20.44 %) vs control. In contrast, LP levels and apoptotic cell counts were significantly lower in the ASeS group vs the A group. Histopathological changes and renal apoptosis were particularly visible in the ASeD group. Our findings suggest that selenium supplementation provides partial protection against renal toxicity of Aroclor 1254.

Carnosic acid alleviates chlorpyrifos-induced oxidative stress and inflammation in mice cerebral and ocular tissues

Chlorpyrifos is an organophosphate pesticide whose exposure leads to inhibition of acetylcholinesterase (AChE) enzyme and induces oxidative stress, inflammation, and neurotoxicity. The current study was designed to evaluate the efficacy of carnosic acid (CA) in ameliorating CPF-induced cytotoxicity in mice brain and eye tissues. We allocated 40 male Swiss albino mice to receive DMSO 1% solution, oral CA 60 mg/kg/day bw, CPF 12 mg/kg/day bw via gastric gavage, or CPF plus CA at 30 and 60 mg/kg/day bw. Carnosic acid was administered once/day for 14 days, while CPF was administered in the last 7 days of the experiment. Biochemical analysis showed that CPF administration was associated with significant increases in the serum concentrations of interleukin-1β, IL-6, and tumor necrosis factor-α, while it was associated with significant reductions in serum AChE levels in mice. Moreover, CPF-intoxicated mice exhibited significantly higher levels of malondialdehyde and nitric oxide in the brain and eye tissues. However, they had significantly lower levels of reduced glutathione, glutathione peroxidase, superoxide dismutase, and catalase in comparison with normal controls. Pretreatment with CA at 30 and 60 mg/kg/day bw for 14 days significantly alleviated all the aforementioned CPF-induced alterations in a dose-dependent manner; more frequent restorations of the normal control ranges were observed in the higher dose group. In conclusion, CA offers a neuroprotective effect against CPF-induced oxidative stress and inflammation and should be further studied in upcoming experimental and clinical research.

Adolescent exposure to environmental level of PCBs (Aroclor 1254) induces non-alcoholic fatty liver disease in male mice

Polychlorinated biphenyls (PCBs) are persistent organic pollutants found in various environmental media, and there is growing evidence that PCBs may contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The purposes of this study were to investigate whether environmental level of Aroclor 1254 (a commercial mixture of PCBs) exposure to adolescent male mice could induce the development of NAFLD and the mechanisms involved. Twenty-one-day-old male C57BL/6 mice were exposed to Aroclor 1254 (0.5-500 μg/kg body weight) by oral gavage once every third day for 60 days. The results showed that exposure to Aroclor 1254 increased body weight and decreased the liver-somatic index in a dose-dependent manner. Aroclor 1254 administration increased lipid accumulation in the liver and induced the mRNA expression of genes associated with lipogenesis, including acetyl-CoA carboxylase 1 (Acc1), acetyl-CoA carboxylase 2 (Acc2) and fatty acid synthase (Fasn). Moreover, Aroclor 1254 decreased peroxisome proliferator-activated receptor alpha (PPARα) signaling and lipid oxidation. In addition, we found that Aroclor 1254 administration induced oxidative stress in mouse liver and elevated the protein level of cyclooxygenase 2 (COX-2), an inflammatory molecule, possibly via the endoplasmic reticulum (ER) stress inositol-requiring enzyme 1α-X-box-binding protein-1 (IRE1α-XBP1) pathway, but not the nuclear factor-κB (NF-κB) pathway. In summary, adolescent exposure to environmental level of PCBs stimulated oxidative stress, ER stress and the inflammatory response and caused NAFLD in male mice. This work provides new insight into the idea that adolescent exposure to environmental level of PCBs might induce the development of NAFLD under the regulation of ER stress in males.

Oxidative Potential of Chemical Mixtures Extracted from Contaminated Galveston Bay, TX Seafood Using a Human Cell Co-culture Model

Increasing levels of pollution in Galveston Bay, TX, are of significant concern for populations that directly depend on fishing activities. Efforts to evaluate contaminant levels in commercial fish have been largely limited to the quantification of chemical mixtures in fish tissue, but little information exists about the toxicological potential of these chemicals on consumption of contaminated seafood. The present study makes use of a human cell co-culture model, mimicking the digestive system, to address the oxidative potential of chemical mixtures in seafood. Chemical extractions were performed on fillets from three fish species and oysters collected from different areas in Galveston Bay. The resulting extracts were used to expose intestinal and liver cells before the measurement of cytotoxicity and activity of antioxidant enzymes. The pesticide 4,4'-DDE was found in nearly all samples from all sites in concentrations ranging from 0.23-9.4 µg/kg. Similarly, total PCBs found in fish and oyster tissue ranged from 0.68-65.65 µg/kg, with PCB-118 being the most common congener measured. In terms of cytotoxicity, oyster extracts led to significant cell mortality, contrary to observations for fish extracts. Antioxidant enzymes, while not directly related to the presence of chemical mixtures in tissue, presented evidence of potential increases in activity from spotted trout extracts. Observations from this study suggest the need to evaluate toxicological aspects of contaminated seafood and support the use of in vitro models for the screening of accumulated chemicals.

Pro-oxidant effects of a high α-tocopherol dose on kidney antioxidant biomarkers and histopathological aspects

The aim of this study is to evaluate the effect of α-tocopherol supplementation at two doses (600 and 1200 mg × kg^-1) on kidney antioxidant status and the histopathological changes in Wistar rats after 12 weeks of exposure at different diets. Forty rats has been divided into 4 groups of 10 rats each, the control group received basal diet with 5 % fresh sunflower oil (FSO), the second group: 5 % oxidized sunflower oil (OSO), the third group: 5 % OSO supplemented with 600 mg × kg^-1 α-tocopherol and the fourth group: 5 % OSO supplemented with 1200 mg × kg^-1 α-tocopherol. In OSO groups, the results showed highly significant increases of LPO (from 31.3 ± 0.9 to 53.8 ± 1.2 nmol of MDA formed/min/mg protein, p < 0.0001) with a significant decrease (p < = 0.001) of the antioxidant enzymatic activities (CAT, SOD, GPX, GR and G6PDH), body weight (339 ± 9 to 290 ± 3 g) and α-tocopherol levels (13.6 ± 0.6 to 6.5 ± 0.4 μg/mg protein). In OSO groups with 600 mg × kg^-1 α-tocopherol, an antioxidant effect was found, reflected by a return of the parameters to values similar to those of the control group. However, higher doses of α-tocopherol (1200 mg × kg^-1) induced a depletion of antioxidant status, α-tocopherol levels (6.0 ± 0.3 μg/mg protein, p < 0.001) and a very highly significant rise (p < 0.0001) of LPO content (54.86 ± 0.01 nmol of MDA formed/min/mg protein). The kidney tissues also showed changes in glomerular, severe inflammatory cells infiltration, and formation of novel vessels. So, we can conclude that the oxidative stress is attenuated by a moderate administration of 600 mg × kg^-1 α-tocopherol, while a pro-oxidant effect occurs at 1200 mg × kg^-1 α-tocopherol.

Age- and sex-dependent variation in the activity of antioxidant enzymes in the brown trout (Salmo trutta)

Oxidative stress is defined as the imbalance between pro-oxidant and antioxidant molecules in favor of the former and it represents one of the main driving forces of aging. To counteract the harmful effects of oxidative stress, organisms evolved a complex antioxidant system. According to the free radical theory of aging, while the production of reactive oxygen species (ROS) increases with age, the antioxidant defenses decline. Although this relationship has been investigated in diverse vertebrate taxa, the information in fish is scant and inconsistent, particularly for wild populations. Thus, the aim of the present study was the investigation of age- and sex-related changes of the antioxidant enzymes activity in free-living individuals of the brown trout (Salmo trutta). We measured the activity of the main enzymes involved in antioxidant protection, namely superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST), as well as lipid peroxidation, in the gills and the liver dissected from brown trout (1+- to 5+-year-old). A significant age-dependent variation in the activity of antioxidant enzymes was noted, with the exception of CAT. GPx activity followed a significant increasing trend with age in both the organs, while SOD decreased in the liver. Increased GST activity was found in the gills only. Lipid peroxidation levels significantly decreased with age in both the organs. SOD and CAT showed sex-dependent differences in the liver of brown trout, with males showing lower enzymatic activity than females. Our data contribute to improve the knowledge on the relationship between antioxidant enzyme activity, aging, and sex in fish.

Improvement of Serum Biochemical Parameters and Hematological Indices Through α-Tocopherol Administration in Dietary Oxidized Olive Oil Induced Toxicity in Rats

Dietary oxidized olive oil, alone or in combination with different doses of α-tocopherol, were given to Swiss albino rats for 30 days; in order to determine its role in oxidative stress and fatty liver, induced by the oxidized olive oils. Serum biochemical parameters and hematological indices of blood were analyzed. The liver was analyzed for histopathological changes, lipid peroxidation, and polar triacylglycerols composition. Results revealed that there was a significant decline in the serum total cholesterol, triglycerides, LDL, glucose and ALT; while a significant increase occurred in the serum HDL levels through the supplementation of α-tocopherol in male and female rats. Hematological parameters were almost in the normal reference range in the groups that were fed α-tocopherol, alone or in combination with oxidized oil, while being significantly altered by the oxidized olive oil. There were acute hepatitis and necrosis in the liver with no fatty changes after feeding with oxidized olive oil, along with varying doses of α-tocopherol. Higher amounts of polar compounds were present in female rats (15.2–93.1 μg/g) compared to male rats (12.2–82.3%) that correspond to the supplementation of α-tocopherol in combination with oxidized oil. Lipid oxidation in liver was minimized by tocopherol, while an increase occurred in the accumulation of oxidized lipids in the liver. These findings revealed that tocopherol is beneficial against the oxidized oil induced biochemical and hematological changes and lipid peroxidation but causes fatty accumulation in the liver. Therefore, the role of tocopherol in patients with fatty liver disease may be considered, as tocopherol may increase the chance of survival.

Toxicity evaluation of 4,4'-di-CDPS and 4,4'-di-CDE on green algae Scenedesmus obliquus: growth inhibition, change in pigment content, and oxidative stress

Polychlorinated diphenyl sulfides and polychlorinated diphenyl ethers are two types of dioxin-like pollutants, which are prevalent in aquatic environments. However, to date, limited information is available regarding their toxicity to green algae. In this study, growth inhibition, effect on pigment content, and oxidative stress potentials of 4,4'-di-CDPS and 4,4'-di-CDE on green algae Scenedesmus obliquus were investigated. The results indicate that the EC₅₀ values of 4,4'-di-CDPS after 24, 48, 72, and 96 h of exposure were 1.736, 1.172, 0.994, and 0.820 mg/L, while the corresponding values for 4,4'-di-CDE were 0.697, 1.087, 0.833, and 0.327 mg/L. As compared to the control group, most of the measured pigment content in algal cells significantly decreased after 96-h exposure to these two chemicals, suggesting their suppressive capability on the photosynthesis process in algal cells. Additionally, oxidative stress occurred as demonstrated by the significantly inhibited activities of the antioxidant enzymes (total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GPx)), and high increases in malondialdehyde (MDA) content in all 4,4'-di-CDE-treated groups and some moderate-dose and high-dose treatments with 4,4'-di-CDPS. Acute toxicity tests and biochemical analysis showed that 4,4'-di-CDE was more toxic than 4,4'-di-CDPS on S. obliquus.

GC-MS analysis and hepatoprotective activity of the n-hexane extract of Acrocarpus fraxinifolius leaves against paracetamol-induced hepatotoxicity in male albino rats

CONTEXT

In Egypt, the burden of liver diseases is exceptionally high.

OBJECTIVE

To investigate the components of the n-hexane extract of Acrocarpus fraxinifolius Arn. (Leguminosae) and its hepatoprotective activity against paracetamol (APAP)-induced hepatotoxicity in rats.

MATERIAL AND METHODS

TRACE GC ultra gas chromatogaphic spectrometry was used for extract analysis. Thirty albino rats were divided into six groups (five rats in each). Group 1 was the healthy control; Groups 2 and 3 were healthy treated groups (250 and 500 mg/kg b.w. of the extract, respectively) for seven days. Group 4 was hepatotoxicity control (APAP intoxicated group). Groups 5 and 6 received APAP + extract 250 and APAP + extract 500, respectively.

RESULTS

Chromatographic analysis revealed the presence of 36 components. Major compounds were α-tocopherol (18.23%), labda-8 (20)-13-dien-15-oic acid (13.15%), lupeol (11.93%), phytol (10.95%) and squalene (7.19%). In the acute oral toxicity study, the mortality rates and behavioural signs of toxicity were zero in all groups (doses from 0 to 5 g/kg b.w. of A. fraxinifolius). LD₅₀ was found to be greater than 5 g/kg of the extract. Only the high dose (500 mg/kg b.w.) of extract significantly alleviated the liver relative weight (4.01 ± 0.06) and biomarkers, as serum aspartate aminotransferase (62.87 ± 1.41), alanine aminotransferase (46.74 ± 1.45), alkaline phosphatase (65.96 ± 0.74), lipid profiles (180.39 ± 3.51), bilirubin profiles (2.30 ± 0.06) and hepatic lipid peroxidation (114.20 ± 2.06), and increased body weight (11.58 ± 0.20), serum protein profile (11.09 ± 0.46) and hepatic total antioxidant capacity (23.78 ± 0.66) in APAP-induced hepatotoxicity in rats.

CONCLUSION

Our study proves the antihepatotoxic/antioxidant efficacies of A. fraxinifolius hexane extract.

Protective effects of Ziziphora tenuior extract against chlorpyrifos induced liver and lung toxicity in rat: Mechanistic approaches in subchronic study

Chlorpyrifos (CPF) is one of the most widely used organophosphorus, which has spurred renewed interest. This study was conducted to investigate the protective effect of ziziphora tenuior extract against CPF-induced liver and lung toxicity. This study conducted 8-week rat sub-chronic toxicity study and then the effect of ziziphora tenuior extract in 3 different doses (40, 80, 160 mg/kg) was determined. We administrated maximum tolerated dose of CPF (6.75 mg/kg) by gavage for 8 weeks (5 times in week) to male rats. Rats were sacrificed 24 h after last dose and the biochemical analysis, which confirms involvement of oxidative stress in the pathogenesis of CPF toxicity in liver including increased in lipid peroxidation, protein carbonyl content, and ROS formation, glutathione depletion, decreased of antioxidant effect via frap oxidation and cytochrome c expulsion. In addition, pathological lesions confirm the dysfunction of the organs (liver and lung). In addition, using of ziziphora extract as an antioxidant is resulted in amelioration of oxidative stress marker in liver and lung damage. In conclusion, the current study revealed that CPF toxicity is related to oxidative stress and induction of cell death signaling and cotreatment with ziziphora extract is recommended in the routine therapy for the protection against CPF induced liver and lung tissue damage.

Ameliorative effect of α-tocopherol on polychlorinated biphenyl (PCBs) induced testicular Sertoli cell dysfunction in F1 prepuberal rats

The study was conducted to investigate the protective role of α-tocopherol against polychlorinated biphenyls (PCBs) induced effect in Sertoli cell function of F₁ prepuberal rats. Dams were grouped into six; each group consists of six animals. Group 1-control treated with corn oil as vehicle, group II- 0.5mgPCBs/kg bw/day, group III- 0.5mgPCBs/kg bw/day with α-tocopherol (50mg α-tocopherol/kg bw/day), group IV- 1mgPCBs/kg bwt/day, group V- 1mgPCBs/kg bw/day with α-tocopherol (50mg α-tocopherol/kg bw/day) and group VI - α-tocopherol alone treated orally from postpartum day1-20. Male offspring rats were euthanized on post natal day 21. Testes were collected for the histological examination and Sertoli cell isolation. The protein levels of follicle-stimulating hormone receptor, androgen binding protein, androgen receptor, estrogen receptor α & β, Inhibin-β, transferrin, claudin-11, occludin, E-cadherin, connexin-43, c-fos, c-jun, SF1, USF1 & 2 were studied using western blot method. The testicular architecture was affected in the PCBs exposed rats but this effect was restored by α-tocopherol supplementation. PCBs decreased the protein levels of FSHR, AR, ABP, ERα & β, transferrin, claudin-11, occludin, E-cadherin, connexin-43, c-fos, c-jun, SF1, USF1 & 2 whereas inhibin-β protein level was found to be increased in Sertoli cells. These results suggested that α-tocopherol has ameliorative role against PCBs induced testicular Sertoli cell dysfunction in F₁ progeny.

The toxic effects of polychlorinated biphenyl (Aroclor 1242) on Tm3 Leydig cells

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disrupt endocrine function in biological systems, especially in the male reproductive system. Previous studies on the reproductive toxicity of PCBs have focused on the impairment of spermatogenesis, disruption of steroidogenesis, decreased sperm number, and infertility. Aroclor 1242 is a commercial mixture with an average of 42% chlorine by weight. The purpose of the present study was to elucidate the hazardous effects of Aroclor 1242 on Leydig cells through an evaluation of cell viability, lipid peroxidation, hydroxyl radicals, H2O2 production, antioxidant enzymes, and steroidogenic enzymes. Leydig cells were exposed to Aroclor 1242 for 24 h under basal and luteinizing hormone-stimulated conditions at different concentrations (ranging from 10−16 M to 10−6 M). After incubation, Leydig cells were measured for cell viability, lipid peroxidation, reactive oxygen species (hydroxyl radical and H2O2), antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase), and steroidogenic enzymes (3β-hydroxysteroid dehydrogenase [HSD] and 17β-HSD). The results showed that cell viability was reduced only at Aroclor 1242 concentrations of 10−6 M and 10−8 M, whereas lipid peroxidation and reactive oxygen species increased relative to the concentration. Furthermore, antioxidant systems and steroidogenesis were interrupted to varying degrees, relative to the concentration. These findings suggest that exposure to Aroclor 1242 at high concentrations may result in detrimental effects to Leydig cell homeostasis. In addition, Aroclor 1242 may impair steroidogenesis, especially testosterone biosynthesis, by inhibiting two important steroidogenic enzymes.

Concentrations of vitamin A, E, thyroid and testosterone hormones in blood plasma and tissues from emaciated adult male Arctic foxes (Vulpes lagopus) dietary exposed to persistent organic pollutants (POPs)

The aim of the present study was to investigate the relationships and effects of oral POP exposure on retinol (vitamin A), α-tocopherol (vitamin E), thyroid hormones and testosterone in emaciated adult farmed Arctic foxes. Eight brother-pairs were exposed to either a diet containing naturally POP-contaminated minke whale blubber (Balaenoptera acutorostrata) (n=8), or a control diet containing pig (Sus scrofa) fat as the primary fat source (n=8) for 22 months. In the whale blubber containing feed the ∑POPs concentration was 802ng/g w.w. and it was 24ng/g w.w. in control feed. The liver mass was significantly higher and the ratio of FT4 (free thyroxine):FT3 (free triiodothyronine) was significantly lower in the POP exposed group as compared to the control group given feed with pig fat (both p<0.05). The exposed group revealed lower plasma and liver concentrations of α-tocopherol compared to the control group (both p<0.05). These results indicate that plasma FT4:FT3 ratio and plasma and liver α-tocopherol are valuable biomarker endpoints for chronic oral POP exposure in wild Arctic foxes. Based on this we suggest that plasma FT4:FT3 ratio and plasma and liver α-tocopherol are valuable biomarker endpoints for chronic POP exposure in wildlife Arctic foxes and that these perturbations may affect their health status.

Fresh water fish, Channa punctatus, as a model for pendimethalin genotoxicity testing: A new approach toward aquatic environmental contaminants

Pendimethalin (PND) is one of the common herbicides used worldwide. Fresh water fish, Channa punctatus, was exposed to PND in aquaria wherein its LC50 value was recorded to be 3.6 mg/L. Three sublethal (SL) concentrations, namely, 0.9, 1.8, and 2.7 mg/L were selected for the evaluation of genotoxicity and oxidative stress generated in the fish. In vivo comet assay was carried out in the blood, liver, and gill cells after exposing the fish to aforesaid SL concentrations of PND for 24, 48, 72, and 96 h. The results of the comet assay demonstrated the genotoxicity of PND in all the three tissues. Induction of oxidative stress in the gill cells was affirmed by the increased lipid peroxidation (LPO) and decreased levels of reduced glutathione, superoxide dismutase, and catalase. Frequencies of erythrocytic nuclear abnormalities (ENA) and micronuclei (MN) were also used to assess the genotoxic potential of PND on C. punctatus. MN frequency did not show any enhancement after PND exposure, but the frequency of ENA such as kidney-shaped nuclei, segmented nuclei and lobed nuclei, showed a significant increase after 24-96 h. Thus, ENA seems to be a better biomarker than MN for PND induced genotoxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1520-1529, 2016.

Polychlorinated Biphenyls Induce Oxidative DNA Adducts in Female Sprague-Dawley Rats

Polychlorinated biphenyls (PCBs) are organic chemicals that were traditionally produced and widely used in industry as mixtures and are presently formed as byproducts of pigment and dye manufacturing. They are known to persist and bioaccumulate in the environment. Some have been shown to induce liver cancer in rodents. Although the mechanism of the toxicity of PCBs is unknown, it has been shown that they increase oxidative stress, including lipid peroxidation. We hypothesized that oxidative stress-induced DNA damage could be a contributor for PCB carcinogenesis and analyzed several DNA adducts in female Sprague-Dawley rats exposed to 3,3',4,4',5-pentachlorobiphenyl (PCB 126), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), and a binary mixture (PCB 126 + 153) for 14, 31, and 53 wks. Eight adducts were measured to profile oxidative DNA lesions, including 8-oxo-deoxyguanosine (8-oxo-dG), 1,N(6)-ethenodeoxyadenosine (1,N(6)-εdA), N(2),3-ethenoguanine (N(2),3-εG), 1,N(2)-ethenodeoxyguanosine (1,N(2)-εdG), as well as malondialdehyde (M1dG), acrolein (AcrdG), crotonaldehyde (CrdG), and 4-hydroxynonenal-derived dG adducts (HNEdG) by LC-MS/MS analysis. Statistically significant increases were observed for 8-oxo-dG and 1,N(6)-εdA concentrations in hepatic DNA of female rats exposed to the binary mixture (1000 ng/kg/day + 1000 μg/kg/day) but not in rats exposed to PCB 126 (1000 ng/kg/day) or PCB 153 (1000 μg/kg/day) for 14 and 31 wks. However, exposure to PCB 126 (1000 ng/kg/day) for 53 wks significantly increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, and M1dG. Exposure to PCB 153 (1000 μg/kg/day) for 53 wks increased 8-oxo-dG, and 1,N(6)-εdA. Exposure to the binary mixture for 53 wks increased 8-oxo-dG, 1,N(6)-εdA, AcrdG, 1,N(2)-εdG, and N(2),3-εG significantly above control groups. Increased hepatic oxidative DNA adducts following exposure to PCB 126, PCB 153, or the binary mixture shows that an increase in DNA damage may play an important role in hepatic toxicity and carcinogenesis in female Sprague-Dawley rats.

The Role of Oxidative Stress and Antioxidants in Liver Diseases

A complex antioxidant system has been developed in mammals to relieve oxidative stress. However, excessive reactive species derived from oxygen and nitrogen may still lead to oxidative damage to tissue and organs. Oxidative stress has been considered as a conjoint pathological mechanism, and it contributes to initiation and progression of liver injury. A lot of risk factors, including alcohol, drugs, environmental pollutants and irradiation, may induce oxidative stress in liver, which in turn results in severe liver diseases, such as alcoholic liver disease and non-alcoholic steatohepatitis. Application of antioxidants signifies a rational curative strategy to prevent and cure liver diseases involving oxidative stress. Although conclusions drawn from clinical studies remain uncertain, animal studies have revealed the promising in vivo therapeutic effect of antioxidants on liver diseases. Natural antioxidants contained in edible or medicinal plants often possess strong antioxidant and free radical scavenging abilities as well as anti-inflammatory action, which are also supposed to be the basis of other bioactivities and health benefits. In this review, PubMed was extensively searched for literature research. The keywords for searching oxidative stress were free radicals, reactive oxygen, nitrogen species, anti-oxidative therapy, Chinese medicines, natural products, antioxidants and liver diseases. The literature, including ours, with studies on oxidative stress and anti-oxidative therapy in liver diseases were the focus. Various factors that cause oxidative stress in liver and effects of antioxidants in the prevention and treatment of liver diseases were summarized, questioned, and discussed.

Physiological and oxidative stress biomarkers in the freshwater monosex Nile tilapia, Oreochromis niloticus L., exposed to pendimethalin-based herbicide

Fish are relatively sensitive to changes in their surrounding environment, including increasing pollution. Therefore, the present study was undertaken to evaluate the impact of contamination with the pendimethalin-based herbicide; Stomp(®) 50% EC (50% pendimethalin as emulsive concentrate) on adults of the monosex Nile tilapia Oreochromis niloticus L. A total of 260 fish with body weights of 90 ± 5.0 g were used in the determination of the 96-h LC50 value and of the impacts of acute exposure to pendimethalin on physiological parameters, and oxidative stress and antioxidant biomarkers. The 96-h median lethal concentration (96-h LC50 ) value of pendimethalin for monosex Nile tilapia was determined as 4.92 mg/L. Abnormal behavioral responses of the fish and the toxic symptoms of pendimethalin exposure are described. Acute exposure to pendimethalin induced leukocytosis, hyperglobulinemia, and hyperglycemia, but resulted in nonsignificant changes in other hemato-biochemical parameters. Moreover, pendimethalin increased lipid peroxidation (LPO) and decreased levels of reduced glutathione and antioxidant enzymes; superoxide dismutase, catalase, and glutathione reductase in both liver and gill tissues, in a time-dependent manner, with maximum alterations observed in the gills rather than the liver. We conclude that although pendimethalin is moderately toxic, it does not cause hepatorenal toxicity. However, this herbicide pollutant induces major disturbances to the antioxidant system; induction of oxidative stress and LPO is the proposed toxicodynamic pathway for such stress.

Polychlorinated biphenyls as oxidative stress inducers in liver of subacutely exposed rats: implication for dose-dependence toxicity and benchmark dose concept

Hepatotoxicity is one of the well-documented adverse health effects of polychlorinated biphenyls (PCBs)-persistent organic pollutants widely present in the environment. Although previous studies suggest possible role of oxidative stress, the precise mechanisms of PCB-induced ROS production in liver still remain to be fully assessed. The aim of this study was to evaluate the effects of different doses of PCBs on the parameters of oxidative stress and to investigate whether these effects are dose dependent. Furthermore, a comparison between calculated benchmark doses (BMD) and estimated NOAEL values for investigated parameters, was made. Six groups of male albino Wistar rats (7 animals per group) were receiving Aroclor 1254 dissolved in corn oil in the doses of 0.5, 1, 2, 4, 8, 16 mg PCBs/kg b.w./day by oral gavage during 28 days while control animals were receiving corn oil only. The following parameters of oxidative stress were analyzed in liver homogenates: superoxide dismutase activity, glutathione, malondialdehyde (MDA) and total protein thiol levels. Hepatic enzymes AST, ALT, ALP and protein albumin were also determined in serum as clinical parameters of liver function. Collected data on the investigated parameters were analyzed by the BMD method. The results of this study demonstrate that subacute exposure to PCBs causes induction of oxidative stress in liver with dose-dependent changes of the investigated parameters, although more pronounced adverse effects were observed on enzymatic than on non-enzymatic components of antioxidant protection. The obtained values for BMD and NOAEL support the use of BMD concept in the prediction of health risks associated with PCBs exposure. Furthermore, our results implicate possible use of MDA in PCBs risk assessment, since MDA was the most sensitive investigated parameter with calculated low critical effect dose of 0.07 mg/kg b.w.

Hepatic oxidative status and metal homeostasis disturbance of 2-hydroxylated dioxin in ICR mice

In the present study, the toxic effects of the oral exposure of 2-hydroxylated dioxin (2-HODD) in ICR male mice were examined. The mice were administered different doses (0.2, 2.0 and 20.0mg/kg) of 2-HODD. After 14 days of exposure, the oxidative stress (OS) indicator levels and the essential metal concentrations in the mouse livers were determined. The results showed that the superoxide dismutase (SOD) and the glutathione peroxidase (GPx) activities were increased in the 0.2mg/kg group, whereas they were significantly decreased in the 2.0 and 20.0mg/kg groups. Decreases in the catalase (CAT) activity and the glutathione (GSH) levels, accompanied by increases in the malondialdehyde (MDA) contents, were recorded in all of the 2-HODD-treated groups. The hepatic iron, copper and zinc levels increased in all of the 2-HODD-treated groups. The histological examination of the livers demonstrated swollen cells and inflammation. Dose-dependent changes in both the OS indicators and the hepatic metal levels were observed. In conclusion, a single low dose of 2-HODD significantly perturbed the hepatic OS status and metals homeostasis in the mice.

The protective role of antioxidants in the defence against ROS/RNS-mediated environmental pollution

Overproduction of reactive oxygen and nitrogen species can result from exposure to environmental pollutants, such as ionising and nonionising radiation, ultraviolet radiation, elevated concentrations of ozone, nitrogen oxides, sulphur dioxide, cigarette smoke, asbestos, particulate matter, pesticides, dioxins and furans, polycyclic aromatic hydrocarbons, and many other compounds present in the environment. It appears that increased oxidative/nitrosative stress is often neglected mechanism by which environmental pollutants affect human health. Oxidation of and oxidative damage to cellular components and biomolecules have been suggested to be involved in the aetiology of several chronic diseases, including cancer, cardiovascular disease, cataracts, age-related macular degeneration, and aging. Several studies have demonstrated that the human body can alleviate oxidative stress using exogenous antioxidants. However, not all dietary antioxidant supplements display protective effects, for example, β-carotene for lung cancer prevention in smokers or tocopherols for photooxidative stress. In this review, we explore the increases in oxidative stress caused by exposure to environmental pollutants and the protective effects of antioxidants.

Hepatoprotective effect of curcumin and alpha-tocopherol against cisplatin-induced oxidative stress

Background

cis-Diammineplatinum (II) dichloride (cisplatin) is the important anti-cancer agent useful in treatment of various cancers. Unfortunately, it can produce unwanted side effects in various tissues, including the liver. The present study investigated the possible protective role of curcumin and α-tocopherol against oxidative stress-induced hepatotoxicity in rats upon cisplatin treatment.

Methods

Male Wistar rats were divided into five groups (n = 5). Saline and Cis groups, rats were intraperitoneal (i.p.) injected with normal saline and cisplatin [20 mg/kg body weight (b.w.)], respectively. Cis + α-tocopherol group, Cis + Cur group and Cis + α-tocopherol + Cur group, rats were pre-treated with a single dose of α-tocopherol (250 mg/kg b.w.), curcumin (200 mg/kg b.w.) and combined α-tocopherol with curcumin, respectively, for 24 h prior the administration of cisplatin. After 72 h of first injection, specimens were collected. Liver enzyme, lipid peroxidation biomarker, liver histopathology and gene expression of liver nicotinamide adenine dinucleotide phosphate (NADPH) oxidase were investigated.

Results

Cisplatin revealed a significant increase of hepatic malondialdehyde (MDA) levels and a significant reduction of hepatic superoxide dismutase (SOD) and catalase activities compared to the saline group. It elicited a marked increase of the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and demonstrated the liver pathologies including liver congestion, disorganization of hepatic cords and ground glass appearance of hepatocytes. It also demonstrated a significant increase of NADPH oxidase gene expression compared to saline group. Pre-treatment with combined curcumin and α-tocopherol improved the liver enzymes, lipid peroxidation biomarker, liver histopathology and gene expression of liver NADPH oxidase in cisplatin-treated rats.

Conclusions

The findings indicate that pre-treatment with combined curcumin and α-tocopherol can protect cisplatin-induced hepatotoxicity including the biochemical, histological and molecular aspects. The down-regulations of NADPH oxidase gene expression may be involved in abrogating oxidative stress via reduction of reactive oxygen species (ROS) production.

Anti-depressive effect of polyphenols and omega-3 fatty acid from pomegranate peel and flax seed in mice exposed to chronic mild stress

AIM

In this study polyphenols from pomegranate peel, and n-3 fatty acids with polyphenols from flax seed were evaluated for their anti depression properties in mice exposed to chronic mild stress (CMS).

METHODS

A total of 40 mice initially trained to consume 2% sucrose solution for 3 weeks were then divided into five groups of eight each. The first group was the normal control, the remaining four groups were exposed to CMS but were force fed with either: 10 mL water per kg bodyweight per day; imipramine (a standard antidepressant) 15 mg kg bodyweight; 30 mg per kg bodyweight polyphenol equivalent extract from pomegranate peel; or 30 mg polyphenols per kg bodyweight with omega-3 fatty acids present, for 50 days. At the end, blood and brain were analyzed for various biomarkers of depression.

RESULTS

The flax seed and imipramine groups had significantly increased sucrose consumption, decreased cortisol (blood), decreased epinephrine and norepinephrine concentration, decreased monoamine oxidase A and B activity, and decreased superoxide dismutase activity. Lipid peroxidation was completely inhibited. In contrast, pomegranate peel extract also completely inhibited lipid peroxidation in the brain, and reduced enzyme activity and hormone concentration but to a lesser extent than flax seed.

CONCLUSION

Polyphenols from flax seed with omega-3 fatty acids were able to reduce all the CMS effects tested compared to polyphenols from pomegranate peel.

Carnitine supplementation effects on nonenzymatic antioxidants in young rats submitted to exhaustive exercise stress

Previous studies have demonstrated that exercise stress increases oxidative stress in rats. However, antioxidant supplement therapy effects on reactive oxygen substances are conflicting. We evaluated the effects of carnitine on renal nonenzymatic antioxidants in young rats submitted to exhaustive exercise stress. Wistar rats were divided into 3 groups: (a) control group (not submitted to exercise stress), (b) exercise stress group, and (c) exercise stress and carnitine group. The rats from group 3 were treated with gavage administration of 1 ml of carnitine (5 mg·kg⁻¹) for 7 consecutive days. The animals from groups 2 and 3 were submitted to a bout of swimming exhaustive exercise stress. Kidney samples were analyzed for reactive substances to thiobarbituric acid by malondialdehyde (MDA), reduced glutathione (GSH), and vitamin-E levels. Carnitine treatment attenuated MDA increase caused by exercise stress (1: 0.16 ± 0.02 vs. 2: 0.34 ± 0.07 vs. 3: 0.1 ± 0.01 mmmol per milligram of protein; p < 0.0001). It also increased the renal levels of GSH (1: 23 ± 4 vs. 2: 23 ± 2 vs. 3: 58 ± 9 μmol per gram of protein; p < 0.0001); however, it did not change renal vitamin E (1: 24 ± 5 vs. 2: 27 ± 1 vs. 3: 28 ± 5 μM per gram of tissue; p < 0.001). In conclusion, carnitine improved oxidative stress and partially improved the nonenzymatic antioxidant activity in young rats submitted to exhaustive exercise stress.

Effects of paraoxon on serum biochemical parameters and oxidative stress induction in various tissues of Wistar and Norway rats

This study investigates the effects of different doses of paroxon (POX), an active metabolite of the organophosphate pesticide parathion, on some serum biochemical parameters and induction of oxidative stress in various tissues of female Wistar and Norway rats. The rats were intraperitoneally treated with 0.3, 0.7, 1 and 1.5 mg/kg of POX. The parameters were evaluated after 24h. The results showed that the decreased glutathione level and catalase, glutathione-S-transferase and lactate dehydrogenase activities in tissues of Wistar rat were higher than Norway rat at higher doses of POX. At these concentrations, POX increased superoxide dismutase activity, malondialdehyde level and some serum biochemical indices. In conclusion, POX induces the production of free radicals and oxidative stress in a dose-dependent manner. Induction of oxidative stress in POX-treated rats is in the order of brain > liver > heart > kidney>spleen. Wistar rat is found to be more sensitive to the toxicity of POX compared to Norway rat.

Eggshell thinning and decreased concentrations of vitamin E are associated with contaminants in eggs of ivory gulls

The ivory gull is a high Arctic seabird species threatened by climate change and contaminant exposure. High levels of contaminants have been reported in ivory gull Pagophila eburnea eggs from Svalbard and the Russian Arctic. The present study investigated associations between high levels of contaminants (organochlorinated pesticides (OCPs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), perfluorinated alkyl substances (PFASs) and mercury (Hg)) and three response variables: eggshell thickness, retinol (vitamin A) and α-tocopherol (vitamin E). Negative associations were found between levels of OCPs, PCBs and BFRs and eggshell thickness (p<0.021) and α-tocopherol (p<0.023), but not with retinol (p>0.1). There were no associations between PFASs and mercury and the three response variables. Furthermore, the eggshell thickness was 7-17% thinner in the present study than in archived ivory gull eggs (≤1930). In general, a thinning above 16 to 20% has been associated with a decline in bird populations, suggesting that contaminant-induced eggshell thinning may constitute a serious threat to ivory gull populations globally.

Antioxidative defense and oxidative stress in ringed seals (Pusa hispida) from differently polluted areas

High contaminant levels detected in Baltic seals have been associated with various health effects. In this study several parameters related to antioxidative defense and oxidative stress (concentrations of reduced and oxidised glutathione, lipid hydroperoxide and vitamin E, activities of glutathione reductase, peroxidase and S-transferase, glucose-6-phosphate dehydrogenase, catalase, and superoxidedismutase) were measured in the livers of ringed seals from the Baltic Sea and from a less contaminated reference area, Svalbard, Norway. Seals were caught during two different time periods 1996-1997 and 2002-2007, which represent different levels of contamination. No signs of oxidative damage were found in the Baltic seals. However, glutathione metabolism was enhanced in the ringed seals from the Baltic Sea compared to the seals from Svalbard. The adaptation to dive where repetitive ischemia/reperfusion occurs naturally may contribute to the resistance of oxidative stress and to the capacity to increase enzymatic antioxidant defense in phocid seals. This could explain the similarities in oxidative stress levels despite the differences in antioxidant responses between the ringed seals from the Baltic Sea and Svalbard.

Morphological alterations of Vero cell exposed to coplanar PCB 126 and noncoplanar PCB 153

Polychlorinated biphenyls (PCBs) are widespread, persistent environmental contaminants that display a complex spectrum of toxicological properties. Exposure to PCBs has been associated with morphological anomalies in cell cultures. However, most mechanistic studies of PCBs' toxic activity have been focused on coplanar congeners. It is of importance to determine whether PCB treatment would influence cell configuration and whether these changes would depend on the structural characteristics of PCBs. In this study, we investigated cell morphological alteration in Vero cell cultures after exposure to coplanar PCB 126 and noncoplanar PCB 153. The survival of Vero cells was measured through the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) test. Cytotoxicity results suggested that PCB congeners had a toxic, antiproliferative effect on Vero cells. Morphological studies described structural modifications and provided evidence that apoptosis might be the main cell death pathway in PCB 153-treated cells. The comparison between PCB 126 and PCB 153 indicated that the cell death mechanisms involved in coplanar or noncoplanar PCB congener exposure were different in Vero cells.

PCB153 reduces telomerase activity and telomere length in immortalized human skin keratinocytes (HaCaT) but not in human foreskin keratinocytes (NFK)

Polychlorinated biphenyls (PCBs), ubiquitous environmental pollutants, are characterized by long term-persistence in the environment, bioaccumulation, and biomagnification in the food chain. Exposure to PCBs may cause various diseases, affecting many cellular processes. Deregulation of the telomerase and the telomere complex leads to several biological disorders. We investigated the hypothesis that PCB153 modulates telomerase activity, telomeres and reactive oxygen species resulting in the deregulation of cell growth. Exponentially growing immortal human skin keratinocytes (HaCaT) and normal human foreskin keratinocytes (NFK) were incubated with PCB153 for 48 and 24days, respectively, and telomerase activity, telomere length, superoxide level, cell growth, and cell cycle distribution were determined. In HaCaT cells exposure to PCB153 significantly reduced telomerase activity, telomere length, cell growth and increased intracellular superoxide levels from day 6 to day 48, suggesting that superoxide may be one of the factors regulating telomerase activity, telomere length and cell growth compared to untreated control cells. Results with NFK cells showed no shortening of telomere length but reduced cell growth and increased superoxide levels in PCB153-treated cells compared to untreated controls. As expected, basal levels of telomerase activity were almost undetectable, which made a quantitative comparison of treated and control groups impossible. The significant down regulation of telomerase activity and reduction of telomere length by PCB153 in HaCaT cells suggest that any cell type with significant telomerase activity, like stem cells, may be at risk of premature telomere shortening with potential adverse health effects for the affected organism.

Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

Distribution of vitamins A (retinol) and E (α-tocopherol) in polar bear kidney: Implications for biomarker studies

Vitamins A and E content of inner organs, among these the kidneys, are increasingly being used as an indicator of adverse effects caused to the organism by e.g. environmental contaminants. In general, only a renal sub sample is used for analyses, and it is thus essential to know which part of the organ to sample in order to get a representative value for this important biomarker. The aim here was to assess the distribution of vitamins A (retinol) and E (α-tocopherol) within the polar bear multireniculate kidney (i.e. polar vs. medial position) and also within the cortex vs. medulla of each separate renculi. The results showed no significant difference between the medial and polar renculi with regards to either retinol (p=0.44) or α-tocopherol (p=0.75). There were, however, significant differences between cortex and medulla for both vitamins (retinol, p=0.0003; α-tocopherol, p<0.0001). The kidney cortex contained higher values of both vitamins than the medulla; on average 29% more retinol and 57% more α-tocopherol. Mean concentrations in the medulla was 2.7 mg/kg for retinol and 116 mg/kg for α-tocopherol, and in the cortex 3.5 mg/kg for retinol and 182 mg/kg for α-tocopherol. These results clearly indicate that one should take precautions when analyzing retinol and α-tocopherol in polar bear kidneys. Prior to analysis, the renculi should be separated into medulla and cortex. The results indicated no significant differences between renculi from different parts of the kidney.

Effects of exposure to halogenated organic compounds combined with dietary restrictions on the antioxidant defense system in herring gull chicks

The Herring gull (HG) (Larus argentatus) is naturally exposed to halogenated organic compounds such as polychlorinated biphenyls (PCBs) through its diet. During periods of food scarcity, arctic seabirds experience lipid mobilization, allowing stored lipid soluble contaminants to re-enter the body circulation. In the present study, we investigated the effects of PCB exposure and fasting on the antioxidant defense system in HG chicks. Forty newly hatched chicks were exposed to contaminated cod liver oil for 6weeks and then fasted for 1week. We assessed the hepatic total oxyradical scavenging capacity (TOSC) against peroxynitrite, hydroxyl and peroxyl radicals, and measured glutathione (reduced: GSH, and oxidized: GSSG) levels and the enzymatic activities of catalase, glutathione peroxidase, glutathione reductase and superoxide dismutase. The results show that fasting significantly increased the HOC levels in the HG chick livers. Limited effects were observed on antioxidant responses; significant effects were only found for catalase (CAT) activity, Se-dependent GPX activity and the GSH/GSSG ratio in the exposed and fasted group. CAT and Se-dependent GPX activities correlated negatively with the PCB concentrations within this group, and a nonlinear relationship between glutathione and contaminant levels was also found. These effects were generally not observed after exposure or fasting alone and were likely related to the high PCB levels induced by the combination of exposure and fasting.

Expression of antioxidant genes in renal cortex of PTU-induced hypothyroid rats: effect of vitamin E and curcumin

The present study was undertaken to investigate the effect of vitamin E and curcumin on the expression of antioxidant genes in 6-propyl-2-thiouracil (PTU)-induced hypothyroid rat renal cortex. The levels of lipid peroxidation and protein carbonylation were increased in hypothyroid rat kidney. Co-administration of vitamin E and curcumin to hypothyroid rats resulted in amelioration of lipid peroxidation level, whereas curcumin alone alleviated the protein carbonylation level. The mRNA levels of SOD1 and SOD2 were decreased in hypothyroid rats. Decreased level of SOD1 transcripts was observed in hypothyroid rats supplemented with curcumin alone or co-administrated with vitamin E. Translated products of SOD1 and SOD2 in hypothyroid rats was elevated in response to supplementation of both the antioxidants. Decreased SOD1 and SOD2 activities in hypothyroid rats compared to control were either unaltered or further decreased in response to the antioxidants. Expressions of CAT at transcript and translate level along with its activity were down regulated in hypothyroid rats. Administration of vitamin E to hypothyroid rats resulted in elevated CAT mRNA level. In contrast, expression of CAT protein was elevated in response to both the antioxidants. However, CAT activity was unaltered in response to vitamin E and curcumin. GPx1 and GR mRNA level and the activity of glutathione peroxidase (GPx) were not affected in response to induced hypothyroidism. The activity of GPx was increased in response to vitamin E treatment, whereas decreased GR activity in hypothyroid rats was further declined by the administration of antioxidants. The over all results suggest that vitamin E and curcumin differentially modulate the altered antioxidant defence mechanism of rat kidney cortex under experimental hypothyroidism.

PCB congeners induced mitochondrial dysfunction in Vero cells

Two PCB congeners were assessed for their cytotoxicity on Vero cells, in the attempt to compare their structure-activity relationship and to investigate the role of mitochondria involved in toxicity. Flow cytometry was used to monitor the changes of mitochondrial membrane potential (Δψ(m)), cell size and apoptosis rate. Treatments of Vero cell cultures with both PCB 126 and PCB 153 resulted in loss of cell viability in our experimental conditions. In ortho-substituted PCB 153 treated cells, loss of cell viability was accompanied by decreased Δψ(m) and cell shrinkage. The coplanar congener, PCB 126, had no significant effects on Δψ(m) or cell size in this time period of exposure. These studies showed that PCB 153 is more toxic than coplanar PCB 126 to Vero cells within 24h exposure. The cytotoxicity mechanism caused by coplanar or non-coplanar PCB congener was different, and apoptosis might be the main cell death pathway in PCB 153 treated cells.

Toxicity of the herbicide atrazine: effects on lipid peroxidation and activities of antioxidant enzymes in the freshwater fish Channa punctatus (Bloch)

The present study was undertaken to evaluate the toxicity and effects of a commercial formulation of the herbicide atrazine (Rasayanzine) on lipid peroxidation and antioxidant enzyme system in the freshwater air breathing fish Channa punctatus. The 12, 24, 48, 72 and 96 h LC(50) of atrazine, calculated by probit analysis, were determined to be 77.091, 64.053, 49.100, 44.412 and 42.381 mg·L(-1), respectively, in a semi static system with significant difference (p < 0.05) in LC(10-90) values obtained for different times of exposure. In addition to concentration and time dependent decrease in mortality rate, stress signs in the form of behavioral changes were also observed in response to the test chemical. In fish exposed for 15 days to different sublethal concentrations of the herbicide (1/4 LC(50) = ∼10.600 mg·L(-1), 1/8 LC(50) = ∼5.300 mg·L(-1) and 1/10 LC(50) = ∼4.238 mg·L(-1)) induction of oxidative stress in the liver was evidence by increased lipid peroxidation levels. The antioxidants superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) responded positively in a concentration dependent pattern, thus, suggesting the use of these antioxidants as potential biomarkers of toxicity associated with contaminations exposure in freshwater fishes.

Health effects from long-range transported contaminants in Arctic top predators: An integrated review based on studies of polar bears and relevant model species

The aim of this review is to provide a thorough overview of the health effects from the complexed biomagnified mixture of long-range transported industrial organochlorines (OCs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs) and mercury (Hg) on polar bear (Ursus maritimus) health. Multiple scientific studies of polar bears indicate negative relationships between exposure to these contaminants and health parameters; however, these are all of a correlative nature and do not represent true cause-and-effects. Therefore, information from controlled studies of farmed Norwegian Arctic foxes (Vulpes lagopus) and housed East and West Greenland sledge dogs (Canis familiaris) were included as supportive weight of evidence in the clarification of contaminant exposure and health effects in polar bears. The review showed that hormone and vitamin concentrations, liver, kidney and thyroid gland morphology as well as reproductive and immune systems of polar bears are likely to be influenced by contaminant exposure. Furthermore, exclusively based on polar bear contaminant studies, bone density reduction and neurochemical disruption and DNA hypomethylation of the brain stem seemed to occur. The range of tissue concentration, at which these alterations were observed in polar bears, were ca. 1-70,000 ng/g lw for OCs (blood plasma concentrations of some PCB metabolites even higher), ca. 1-1000 ng/g lw for PBDEs and for PFCs and Hg 114-3052 ng/g ww and 0.1-50 microg/g ww, respectively. Similar concentrations were found in farmed foxes and housed sledge dogs while the lack of dose response designs did not allow an estimation of threshold levels for oral exposure and accumulated tissue concentrations. Nor was it possible to pinpoint a specific group of contaminants being more important than others nor analyze their interactions. For East Greenland polar bears the corresponding daily SigmaOC and SigmaPBDE oral exposure was estimated to be 35 and 0.34 microg/kg body weight, respectively. Furthermore, PFC concentrations, at which population effect levels could occur, are likely to be reached around year 2012 for the East Greenland polar bear subpopulation if current increasing temporal trends continue. Such proposed reproductive population effects were supported by physiological based pharmacokinetic (PBPK) modelling of critical body residues (CBR) with risk quotients >or=1 for SigmaPCB, dieldrin, SigmaPFC and SigmaOHC (organohalogen contaminant). The estimated daily TEQ for East Greenland polar bears and East Greenland sledge dogs were 32-281-folds above WHO SigmaTEQ guidelines for humans. Compared to human tolerable daily intake (TDI), these were exceeded for PCBs, dieldrin, chlordanes and SigmaHCH in East Greenland polar bears. Comparisons like these should be done with caution, but together with the CBR modelling and T-score estimations, these were the only available tools for polar bear risk evaluation. In conclusion, polar bears seem to be susceptible to contaminant induced stress that may have an overall sub-clinical impact on their health and population status via impacts on their immune and reproductive systems.