Subacute exposure to Roundup® changes steroidogenesis and gene expression of the glutathione-glutaredoxin system in rat ovaries: Implications for ovarian toxicity of this glyphosate-based herbicide.

Studies have indicated that glyphosate induces endocrine disruption and may adversely affect the male reproductive system. However, evidence of its effects on ovarian function is poorly understood so far, making further studies necessary on the mechanisms of the glyphosate toxicity in the female reproductive system. The aim of this work was to evaluate the effect of a subacute exposure (28 days) to the glyphosate-based formulation Roundup® (1.05, 10.5 and 105 µg/kg b.w. of glyphosate) on steroidogenesis, oxidative stress, systems involved in cell redox control and histopathological parameters in rat ovaries. Hence we quantify plasma estradiol and progesterone by chemiluminescence; non-protein thiol levels, TBARS, superoxide dismutase and catalase activity by spectrophotometry; gene expression of steroidogenic enzymes and redox systems by real-time PCR; and ovarian follicles by optical microscopy. Our results demonstrated that oral exposure increased progesterone levels and the mRNA expression of 3ß-hydroxysteroid dehydrogenase. Histopathological analysis revealed a decrease in the number of primary follicles and an increase in the number of corpus luteum in rats exposed to Roundup®. An imbalance of the oxidative status was also evidenced by decreasing the catalase activity at all groups exposed to the herbicide. Increased lipid peroxidation and gene expression of glutarredoxin and decreased of glutathione reductase were also observed. Our results indicate that Roundup® causes endocrine disruption of hormones related to female fertility and reproduction and changes the oxidative status by altering antioxidant activity, inducing lipid peroxidation, as well as changing the gene expression of the glutathione-glutarredoxin system in rat ovaries.

Bioactive compounds, antioxidant capacity and antitumoral activity of ethanolic extracts from fruits and seeds of Eugenia involucrata DC.

Eugenia involucrata DC. (Myrtaceae) is a native tree species from Brazil that has been scarcely studied. We investigated the phenolic composition, the antioxidant capacity and the antitumoral activity of ethanolic extracts from fruits (FE) and seeds (SE) of E. involucrata. Six anthocyanins were identified by UPLC-PDA/MS/MS in FE, being four derived from cyanidin, and the other ones derived from delphinidin and pelargonidin. Using HPLC-PDA, FE presented a larger number of phenolic compounds (epicatechin, catechin, rutin, ellagic acid, myricetin and quercetin) than SE, which did not show myricetin and quercetin. However, SE showed higher total phenolic content and generally stronger in vitro antioxidant capacity than FE, except that only FE exhibited superoxide radical scavenging activity, which may be attributed to the anthocyanins present in fruits. Additionally, only SE exhibited antitumoral activity in a pancreatic cancer cell line (PANC-1). The antitumoral mechanisms involved imbalance of antioxidant status, alteration of mitochondrial membrane potential, cytoskeleton disassembly and induction of cell death by apoptosis and necrosis. Compared to the standard antitumoral drug gemcitabine, SE exhibited higher antitumoral efficacy and selectivity index. The highest concentration of total phenolics and of specific phenolic compounds bearing antitumoral properties may be related to the antitumoral activity of SE. Our results corroborate previous data of E. involucrata as an important source of bioactive compounds and provide, for the first time, evidences of in vitro antitumoral potential of its seeds on pancreatic cancer cell line.

Exposure to the herbicide 2,4-dichlorophenoxyacetic acid impairs mitochondrial function, oxidative status, and behavior in adult zebrafish.

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most commonly used herbicides worldwide. While the effects of 2,4-D in target organisms are well known, its consequences in nontarget organisms are not fully explained. Therefore, the purpose of this study was to investigate the effects of the herbicide on mitochondrial energy metabolism, oxidative status, and exploratory behavior in adult zebrafish. Animal exposure to 2,4-D increased cytochrome c oxidase and catalase activities and reduced SOD/CAT ratio, moreover, increased the total distance traveled and the number of crossings. Finally, animals exposed to 2,4-D spent more time in the upper zone of the tank and traveled a long distance in the upper zone. Overall, our results indicate the 2,4-D can provoke disabling effects in nontarget organisms. The obtained data showed that exposure to 2,4-D at environmentally relevant concentrations alters mitochondrial metabolism and antioxidant status and disturbs the zebrafish innate behavior.

Exposure to ractopamine hydrochloride induces changes in heart rate and behavior in zebrafish embryos and larvae.

Different veterinary drugs have been widely found in surface and groundwater, affecting non-target organisms. Ractopamine (RAC) is one of these drugs found in water bodies. It is a ß-adrenergic agonist used as a feed additive to modulate the metabolism, redirect nutrients from the adipose tissue towards muscles, and increase protein synthesis in swine, cattle, and turkeys. RAC shows toxicological potential, but there is no data about its impacts on the development of non-target organisms, such as zebrafish (Danio rerio). In this study, we evaluated the effect of the exposure to this feed additive on critical parameters (hatching, survival, spontaneous movement, heart rate, and exploratory and locomotor behavior) in zebrafish embryos and larvae. The animals were exposed to RAC hydrochloride at 0.1, 0.2, 0.85, 8.5, and 85 µg/L. Zebrafish exposed to the drug showed increased heart rate at all tested concentrations and alterations on locomotion and exploratory behavior at 85 µg/L. No changes were observed in the survival, hatching rate and spontaneous movement. Our results suggest that RAC present in the environment can induce disabling effects on non-target organisms and elicit an ecological imbalance by increasing the animals' vulnerability to predation due to greater visibility.

A mixture of fipronil and fungicides induces alterations on behavioral and oxidative stress parameters in zebrafish.

Pesticide commercial mixtures, including the insecticide fipronil and the fungicides pyraclostrobin and methyl-thiophanate, have been used in concomitant pest control, facilitating agricultural management. Their widespread use can lead to soil and water contamination and potentially induce damages in the ecosystem, producing toxic effects in non-target organisms. Despite their toxicological potential, their effects on behavioral and biochemical parameters are not well understood. Here we investigated the effects of the mixture of fipronil and fungicides (MFF) pyraclostrobin and methyl- thiophanate on behavioral and biochemical parameters of oxidative stress in adult zebrafish. Animals exposed to the highest MFF tested concentration showed a decrease in the total distance traveled and in the number of crossings in the different zones of the tank. Furthermore, animals exposed to highest MFF tested concentration spent more time in water surface. In addition, our data showed that the exposure to this preparation promoted a decrease in non-protein thiol content as well as in catalase activity. Finally, pesticide exposure induced an increase in the superoxide dismutase/catalase ratio. Our results indicate that alterations in behavioral and oxidative parameters are involved in MFF toxicity in zebrafish. The antioxidant mechanisms analyzed were altered in concentrations that did not affect zebrafish behavior. Therefore, the assessment of oxidative stress parameters in zebrafish brains could be very useful to detect the early effects of environmental exposure to the MFF.

Protective effect of Uncaria tomentosa extract against oxidative stress and genotoxicity induced by glyphosate-Roundup® using zebrafish (Danio rerio) as a model.

Oxidative stress and DNA damage are involved in the glyphosate-based herbicide toxicity. Uncaria tomentosa (UT; Rubiaceae) is a plant species from South America containing bioactive compounds with known beneficial properties. The objective of this work was to evaluate the antioxidant and antigenotoxic potential of UT extract in a model of acute exposure to glyphosate-Roundup® (GR) in zebrafish (Danio rerio). We showed that UT (1.0 mg/mL) prevented the decrease of brain total thiols, the increase of lipid peroxidation in both brain and liver, and the decrease of liver GPx activity caused after 96 h of GR (5.0 mg/L) exposure. In addition, UT partially protected against the increase of micronucleus frequency induced by GR exposure in fish brain. Overall, our results indicate that UT protects against damage induced by a glyphosate-based herbicide by providing antioxidant and antigenotoxic effects, which may be related to the phenolic compounds identified in the extract.

Ractopamine hydrochloride induces behavioral alterations and oxidative status imbalance in zebrafish.

The occurrence of ractopamine (RAC) hydrochloride in water bodies is of significant concern due to its ecological impacts and toxicity to humans. RAC hydrochloride is a ß-adrenergic agonist drug used as a feed additive to (1) improve feed efficiency, (2) rate of weight gain, and (3) increase carcass leanness in animals raised for their meat. This drug is excreted by animals in urine and introduced into the environment affecting nontarget organisms including fish. In wastewater released from farms, RAC concentrations were detected from 0.124 µg/L to 30.1 µg/L, and in levels ranging from 1.3 × 10-5 to 5.4 × 10-4 µg/L in watersheds. The aim of this study was to examine the effects of exposure to RAC at 0.1, 0.2, 0.85, 8.5, or 85 µg/L dissolved in water on behavior and oxidative status in adult zebrafish. At 0.85 µg/L, RAC treatment increased exploratory behavior of zebrafish; while at 8.5 µg/L, decreased locomotor and exploratory activities were noted. With respect to oxidative stress biomarkers, results showed that RAC at 0.2 µg/L induced lipid peroxidation and elevated total thiol content in zebrafish brain. All drug tested concentrations produced a fall in nonprotein thiol content. Finally, RAC at 0.85, 8.5, or 85 µg/L increased catalase enzyme activity. Our results demonstrated that the exposure to RAC induced behavioral alterations and oxidative stress in zebrafish.

Effects of hydroalcoholic extract of Celtis iguanaea on markers of cardiovascular diseases and glucose metabolism in cholesterol-fed rats

ABSTRACT Celtis iguanaea (Jacq.) Sarg., Cannabaceae, is popularly used in the treatment of diabetes mellitus. However, chemical and pharmacological investigations are lacking. In this study, we investigated the effects of the hydroalcoholic extract from C. iguanaea on markers of cardiovascular diseases and the glucose metabolism in cholesterol-fed rats. Therefore, hypercholesterolemic rats (1% cholesterol) were orally treated with C. iguanaea extract (C-150, CI-300, or CI-600 mg/kg) or simvastatin (4 mg/kg) (n = 6) once a day (30 days) with a hypercholesterolemic diet. A control group (C) was given saline. C. iguanaea extract showed significant decreases in serum levels of total cholesterol, LDL-cholesterol, HMG-CoA-reductase, interleukin-1 and 6, TNF-α and IFN-γ when compared to group C (p < 0.001). Hypoglycemic effects were observed along with a decrease of the activity of sucrase (CI-600), maltase (CI-150, CI-300), and an increase in muscle glycogen levels (CI-300). Antioxidant effects were observed in plasma by the decrease of TBARS and increase of nonprotein thiols levels (CI-600). The histopathological analysis showed a significant decrease in the liver fat area for C. iguanaea extract compared to group C (p < 0.001). Our results suggest that the biological effects of C. iguanaea extract could be related to the flavonoids that possibly exert antioxidant, enzymatic inhibitory, and insulin-mimetic effects.

Prevention of unpredictable chronic stress-related phenomena in zebrafish exposed to bromazepam, fluoxetine and nortriptyline.

RATIONALE: Several model organisms have been employed to study the impacts of stress on biological systems. Different models of unpredictable chronic stress (UCS) have been established in rodents; however, these protocols are expensive, long-lasting, and require a large physical structure. Our group has recently reported an UCS protocol in zebrafish with several advantages compared to rodent models. We observed that UCS induced behavioral, biochemical, and molecular changes similar to those observed in depressed patients, supporting the translational relevance of the protocol. OBJECTIVES: Considering that a pharmacological assessment is lacking in this zebrafish model, our aim was to evaluate the effects of anxiolytic (bromazepam) and antidepressant drugs (fluoxetine and nortriptyline) on behavioral (novel tank test), biochemical (whole-body cortisol), and molecular parameters (cox-2, tnf-α, il-6, and il-10 gene expression) in zebrafish subjected to UCS. RESULTS: We replicated previous data showing that UCS induces behavioral and neuroendocrine alterations in zebrafish, and we show for the first time that anxiolytic and antidepressant drugs are able to prevent such effects. Furthermore, we extended the molecular characterization of the model, revealing that UCS increases expression of the pro-inflammatory markers cox-2 and il-6, which was also prevented by the drugs tested. CONCLUSIONS: This study reinforces the use of zebrafish as a model organism to study the behavioral and physiological effects of stress. The UCS protocol may also serve as a screening tool for evaluating new drugs that can be used to treat psychiatric disorders with stress-related etiologies.

Hypolipidemic and antiatherogenic effects of Cynara scolymus in cholesterol-fed rats

ABSTRACT Cynara scolymus L., Asteraceae, are traditionally used to treat dyspepsia. This study evaluated the hypolipidemic and antiatherogenic effects of an aqueous extract prepared from the leaves of C. scolymus in rat's model. Hypercholesterolemic rats (1% cholesterol and 0.5% cholic acid for 15 days) were treated (0.5 ml/200 g) with extract of C. scolymus (150, 300, or 600 mg/kg p.o.; n = 6) or simvastatin (4 mg/kg p.o.; n = 6) once per day for 30 days along with hypercaloric diet. A control group (C) was given water (0.5 ml/200 g; n = 6). A high-cholesterol diet was maintained throughout the treatment period. Rats treated with extract of C. scolymus (150, 300, or 600 mg/kg) and simvastatin showed significant decreases in serum levels of total cholesterol (−46.9%, −51.9%, −44%, and −41.9%, respectively) and low-density lipoprotein-cholesterol (LDL-C; −52.1%, −54.8%, −51.9%, and −46.7%, respectively), compared with group C (p < 0.005). Biochemical analyses revealed significant decrease in the concentration of IL-1, IL-6, TNF-α, IFN-γ, C-reactive protein, oxidized-LDL, and antioxidized-LDL in rats treated with extract of C. scolymus (150, 300, or 600 mg/kg). There were no differences in serum ALT enzyme activity between the groups. Our results suggest that hypolipidemic and antiatherogenic effects could be related with the presence of polar substances present in aqueous extract of C. scolymus.

Involvement of the catecholaminergic system on the antidepressant-like effects of Alpinia zerumbet in mice.

CONTEXT: The traditional uses of Alpinia zerumbet (Pers.) B.L.Burtt & R.m.SM (Zingiberaceae), popularly known as colonia or pacová, suggest that the species has antihypertensive, diuretic, and sedative properties. We previously reported that an ethanol extract of Alpinia zerumbet (HEA) significantly reduced the immobility time in the tail suspension test (TST), similar to the tricyclic antidepressant imipramine. Moreover, HEA presented antioxidant and anxiolytic-like effects in mice. OBJECTIVE: The objective of this study is to investigate the involvement of monoaminergic and glutamatergic systems in the antidepressant-like effects of this species. MATERIALS AND METHODS: A hydroethanolic extract prepared with the leaves of A. zerumbet was assayed in the TST in male Swiss mice (800 mg/kg, p.o.). Synthesis inhibitors (AMPT, inhibitor of tyrosine hydroxylase, 100 mg/kg, i.p.; and PCPA, irreversible tryptophan hydroxylase inhibitor, 100 mg/kg, i.p.) and a specific glutamate antagonist (AMPA receptor antagonist NBQX, 10 mg/kg, i.p.) were used prior testing. RESULTS: Pre-treatment with the noradrenergic/dopaminergic inhibitor AMPT fully abolished the anti-immobility effects of HEA, with the two-way ANOVA yielding a significant interaction between pre-treatment and treatment (F1,32 = 10.0, p < 0.01); no interaction was observed with the serotonergic inhibitor PCPA (F1,32 = 0.33, p > 0.05) or NBQX (F1,32 = 0.21, p > 0.05). CONCLUSION: These results indicated that HEA most likely acts through the dopaminergic and/or noradrenergic system but not through the serotoninergic or glutamatergic systems. This study reinforces the idea that the available biodiversity in Brazil can serve as a basis for innovation in the development of new drugs.

Antidepressant-Like and Antioxidant Effects of Plinia trunciflora in Mice.

The jaboticaba tree, Plinia trunciflora (O. Berg) Kausel, is popularly named "jabuticabeira" in Brazil and is used in folk medicine to treat diabetes and chronic inflammation of the tonsils, but studies evaluating the central effects of this species are limited. This study evaluated the antidepressant-like and antioxidant effects of P. trunciflora (PT) aqueous extract, in which five different anthocyanins were identified. PT showed significant ferric-reduction power and DPPH radical scavenging activity in vitro and reduced lipid peroxidation both in vitro and ex vivo. At the behavioural level, PT (400 and 800 mg/kg, i.p.) dose-dependently reduced immobility time in the tail suspension test in Swiss male mice. The identification of bioactive compounds accompanied by the in vitro and ex vivo antioxidant activity of PT suggests that these activities might be related to the antidepressant-like activity of P. trunciflora.

Hypolipidemic effects of Solidago chilensis hydroalcoholic extract and its major isolated constituent quercetrin in cholesterol-fed rats.

CONTEXT: Despite several studies on the effects of Solidago chilensis Meyen (Asteraceae), the phytochemical and hypolipidemic properties remain underappreciated. OBJECTIVE: This study evaluates the hypolipidemic and antioxidant effects of hydroalcoholic extract (HE) and quercetrin from S. chilensis aerial parts in cholesterol-fed rats. MATERIALS AND METHODS: The HE was analyzed by high-performance liquid chromatography, followed by quercetrin isolation. Hypercholesterolemic rats (1% cholesterol and 0.5% cholic acid for 15 d) were treated with HE (150, 300, and 600 mg/kg p.o.; n = 6), simvastatin (4 mg/kg p.o.; n = 6), or quercetrin (10 mg/kg p.o.; n = 6) once a day for 30 d. During this period, a high-cholesterol diet was maintained until the 30th day of treatment. RESULTS: Rats treated with HE (150, 300, and 600 mg/kg) and quercetrin showed decreased serum levels of total cholesterol (-19.9, -27.5, -31.0, and -39.4%), lipoprotein-cholesterol (-36.0, -37.5, -43.3, and -59.4%), and triacylglycerides (-15.6, -23.5, -29.8, and -27.2%) when compared with the control group similar to simvastatin. Moreover, treatment with HE and quercetrin decreased hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity (35.1% on average) and increased fecal cholesterol levels (38.2% on average). DISCUSSION AND CONCLUSIONS: Our results suggest that hypolipidemic effects of HE are associated with it modulating the activity of HMG-CoA reductase and its interference in the reabsorption and/or excretion of intestinal lipids. Solidago chilensis and its main constituent, quercetrin, may thus be effective as cholesterol-lowering agents and in preventing atherosclerosis.

Subchronic atrazine exposure changes defensive behaviour profile and disrupts brain acetylcholinesterase activity of zebrafish.

Animal behaviour is the interaction between environment and an individual organism, which also can be influenced by its neighbours. Variations in environmental conditions, as those caused by contaminants, may lead to neurochemical impairments altering the pattern of the behavioural repertoire of the species. Atrazine (ATZ) is an herbicide widely used in agriculture that is frequently detected in surface water, affecting non-target species. The zebrafish is a valuable model organism to assess behavioural and neurochemical effects of different contaminants since it presents a robust behavioural repertoire and also all major neurotransmitter systems described for mammalian species. The goal of this study was to evaluate the effects of subchronic ATZ exposure in defensive behaviours of zebrafish (shoaling, thigmotaxis, and depth preference) using the split depth tank. Furthermore, to investigate a putative role of cholinergic signalling on ATZ-mediated effects, we tested whether this herbicide alters acetylcholinesterase (AChE) activity in brain and muscle preparations. Fish were exposed to ATZ for 14days and the following groups were tested: control (0.2% acetone) and ATZ (10 and 1000µg/L). The behaviour of four animals in the same tank was recorded for 6min and biological samples were prepared. Our results showed that 1000µg/L ATZ significantly increased the inter-fish distance, as well as the nearest and farthest neighbour distances. This group also presented an increase in the shoal area with decreased social interaction. No significant differences were detected for the number of animals in the shallow area, latency to enter the shallow and time spent in shallow and deep areas of the apparatus, but the ATZ 1000 group spent significantly more time near the walls. Although ATZ did not affect muscular AChE, it significantly reduced AChE activity in brain. Exposure to 10µg/L ATZ did not affect behaviour or AChE activity. These data suggest that ATZ impairs defensive behaviours of zebrafish, which could be related to its action on brain cholinergic neurotransmission. Moreover, the use of the split depth tank could be an alternative strategy to assess group behaviour and depth preference after exposure to chemical compounds.

Acute exposure to low lead levels and its implications on the activity and expression of cytosolic thioredoxin reductase in the kidney.

Renal thioredoxin reductase-1 (TrxR-1) activity is stimulated at lead doses lower than that necessary to inhibit δ-aminolevulinate dehydratase activity (δ-ALA-D), which is a classical early biomarker of lead effects. Thus, we hypothesized that the activity of TrxR-1 could be a more sensitive early indicator of lead effects than is δ-ALA-D. To evaluate this hypothesis, we assessed the blood and renal TrxR-1 activity and its gene expression along with biomarkers of oxidative damage, antioxidant enzyme activities and biomarkers of lead exposure in rats acutely exposed to lead. A histopathological analysis was performed to verify renal damage. The increase in renal TrxR-1 activity paralleled the increase in the blood and renal lead levels at 6, 24 and 48 hr after the exposure to 25 mg/kg lead acetate (p < 0.05), whereas its expression was increased 24 and 48 hr after exposure. These effects were not accompanied by oxidative or tissue damage in the kidneys. Blood TrxR-1 activity was not affected by lead exposure (up to 25 mg/kg). Erythrocyte δ-ALA-D activity was inhibited 6 hr after the exposure to 25 mg/kg lead acetate (p < 0.05) but recovered thereafter. Renal δ-ALA-D activity decreased 24 and 48 hr after the exposure to 25 mg/kg lead acetate. There were no changes in any parameters at lead acetate doses <25 mg/kg. Our results indicate that blood TrxR-1 activity is not a suitable indicator of lead effects. In contrast, the increase in renal TrxR-1 expression and activity is implicated in the early events of lead exposure, most likely as a protective cellular mechanism against lead toxicity.

Acute restraint stress induces an imbalance in the oxidative status of the zebrafish brain.

The zebrafish (Danio rerio) has become an emergent model organism for translational approaches focused on the neurobiology of stress due to its genetic, neuroanatomical, and histological similarities with mammalian systems. However, despite the increasing number of studies using zebrafish, reports examining the impact of stress on relevant neurochemical parameters are still elementary when compared to studies using rodents. Additionally, it is important to further validate this model organism by comparing its stress response with those described in other species. Here, we evaluated the effects of an acute restraint stress (ARS) protocol on oxidative stress-related parameters in the zebrafish brain. Our data revealed that ARS significantly decreased catalase activity without altering the activity of superoxide dismutase. Oxidative stress was also indicated by increased levels of lipid peroxides. ARS significantly increased the levels of non-protein thiols, although significant changes in total reduced sulfhydryl content were not detected. These results suggest that ARS is an interesting strategy for evaluating the mechanisms underlying the neurochemical basis of the oxidative profile triggered by acute stressors in the zebrafish brain. Furthermore, this protocol may be suitable for screening new compounds with protective properties against oxidative stress, which plays an increasingly important role in many psychiatric disorders.

Blood thioredoxin reductase activity, oxidative stress and hematological parameters in painters and battery workers: relationship with lead and cadmium levels in blood.

Oxidative stress has been shown to be involved in lead and cadmium toxicity. We recently showed that the activity of the antioxidant enzyme thioredoxin reductase (TrxR) is increased in the kidneys of lead-exposed rats. The present study evaluated the blood cadmium and blood lead levels (BLLs) and their relationship with hematological and oxidative stress parameters, including blood TrxR activity in 50 painters, 23 battery workers and 36 control subjects. Erythrocyte δ-aminolevulinate dehydratase (δ-ALA-D) activity and its reactivation index were measured as biomarkers of lead effects. BLLs increased in painters, but were even higher in the battery workers group. In turn, blood cadmium levels increased only in the painters group, whose levels were higher than the recommended limit. δ-ALA-D activity was inhibited only in battery workers, whereas the δ-ALA-D reactivation index increased in both exposed groups; both parameters were correlated to BLLs (r = -0.59 and 0.84, P < 0.05), whereas the reactivation index was also correlated to blood cadmium levels (r = 0.27, P < 0.05). The changes in oxidative stress and hematological parameters were distinctively associated with either BLLs or blood cadmium levels, except glutathione-S-transferase activity, which was correlated with both lead (r = 0.34) and cadmium (r = 0.47; P < 0.05). However, TrxR activity did not correlate with any of the metals evaluated. In conclusion, blood TrxR activity does not seem to be a good parameter to evaluate oxidative stress in lead- and cadmium-exposed populations. However, lead-associated changes in biochemical and hematological parameters at low BLLs underlie the necessity of re-evaluating the recommended health-based limits in occupational exposure to this metal.

Astaxanthin prevents changes in the activities of thioredoxin reductase and paraoxonase in hypercholesterolemic rabbits.

This study explored the effects of the antioxidant astaxanthin on paraoxonase and thioredoxin reductase activities as well as on other oxidative stress parameters and on the lipid profile in hypercholesterolemic rabbits. Rabbits were fed a standard or a hypercholesterolemic diet alone or supplemented with 50, 100 and 500 mg/100 g of astaxanthin for 60 days. Antioxidant enzymes activities, lipid profile and oxidative stress markers were evaluated in the serum. The hypercholesterolemic diet increased lipids, including unsaturated fatty acids level, whereas it decreased saturated fatty acids level. These changes were accompanied by increased levels of oxidized low-density lipoprotein and oxidized low-density lipoprotein antibodies, as well as lipid and protein oxidation. Astaxanthin (100 and 500 mg/100 g) prevented hypercholesterolemia-induced protein oxidation, whereas 500 mg/100 g of astaxanthin decreased protein oxidation per se. The activities of superoxide dismutase and thioredoxin reductase were enhanced, whereas paraoxonase activity was inhibited in hypercholesterolemic rabbits. All astaxanthin doses prevented changes in thioredoxin reductase and paraoxonase activities. This effect was not related to a direct effect of astaxanthin on these enzymes, because in vitro astaxanthin enhanced thioredoxin reductase and had no effect on paraoxonase activity. Astaxanthin could be helpful in cardiovascular diseases by restoring thioredoxin reductase and paraoxonase activities.

Imbalance in superoxide dismutase/thioredoxin reductase activities in hypercholesterolemic subjects: relationship with low density lipoprotein oxidation.

BACKGROUND: There is a relationship among hypercholesterolemia, oxidative stress and inflammation in the atherogenesis. Thus, the objective of the present study was to assess paraoxonase (PON1), superoxide dismutase (SOD) and thioredoxin reductase (TrxR-1) activities and their relationship with lipids, oxidative stress and inflammation in subjects with different low density lipoprotein-cholesterol (LDL) levels. METHODS: Serum lipids, highly sensitive C-reactive protein (hs-CRP), lipid and protein oxidation, oxidized LDL (LDLox) and LDLox autoantibodies (LDLoxAB) levels and enzymes activities were measured in a total of 116 subjects that were divided into the following groups according to their LDL levels: low-LDL group (LDL < 100 mg/dL, n = 23), intermediate-LDL group (LDL 100-160 mg/dL, n = 50) and high-LDL group (LDL > 160 mg/dL, n = 43). RESULTS: The LDLox and hs-CRP levels increased in the high-LDL group (2.7- and 3.7- fold, respectively), whereas the intermediate and high-LDL groups had higher LDLoxAB (2.2- and 3.1-fold) when compared to low-LDL group (p < 0.05). Similarly, SOD activity, the atherogenic index (AI) and protein oxidation were also higher in the intermediate (1.3-, 1.3- and 1.2-fold) and high-LDL (1.6-, 2.3- and 1.6-fold) groups when compared to the low-LDL group (p < 0.05). Lipid oxidation and SOD/TrxR-1 ratio increased only in the high-LDL group (1.3- and 1.6-fold) when compared to the low-LDL group (p < 0.05). The SOD/TrxR-1 ratio was positively correlated to TBARS (r = 0.23, p < 0.05), LDLox (r = 0.18, p < 0.05), LDLoxAB (r = 0.21, p < 0.05), LDL (r = 0.19, p < 0.05) and AI (r = 0.22, p < 0.05). PON1 and TrxR-1 activities were similar among groups. CONCLUSIONS: Some oxidative events initiate when LDL levels are clinically acceptable. Moreover, hypercholesterolemic patients have an imbalance in SOD and TrxR-1 activities that is positively associated to LDL oxidation.

Astaxanthin reduces oxidative stress, but not aortic damage in atherosclerotic rabbits.

We evaluated whether carotenoid astaxanthin (ASX) could prevent oxidative and atherosclerotic damage in rabbits. Rabbits received regular chow (control) or an atherogenic diet (1% cholesterol) alone or supplemented with 50, 100, and 500 mg% ASX for 60 days (n = 5-9 per group). The atherogenic diet increased the serum cholesterol levels and the ratio of the intima/media area in the aortic arch. These changes were not prevented by ASX. Atherosclerotic rabbits showed increased aortic lipid peroxidation and nonprotein thiol group (NPSH) levels along with inhibition of glutathione peroxidase (GSH-Px). All ASX doses attenuated lipid peroxidation and the increase in NPSH but not the inhibition of GSH-Px. Aortic superoxide dismutase (SOD), catalase (CAT), and thioredoxin reductase (TrxR) activities were enhanced in atherosclerotic rabbits. Although all ASX doses prevented the increase in SOD activity, only 100 and 500 mg% ASX prevented the increase in CAT activity. Furthermore, these same doses partially prevented the increase in TrxR activity, while 50 mg% ASX completely prevented the effects of the atherogenic diet on this enzyme. However, ASX did not attenuate the hypercholesterolemia or the atherosclerotic lesions caused by the atherogenic diet at any of the doses evaluated. Our results indicate that although ASX did not prevent hypercholesterolemia or atherosclerotic lesions, it could play a beneficial role by preventing lipid peroxidation and changes in antioxidant enzyme activities.