Selenium modifies glutathione peroxidase activity and glutathione concentration in mice exposed to ozone-provoked oxidative stress

Effect of sodium selenite on chosen anti- and pro-oxidative parameters in rats treated with lithium: A pilot study

BACKGROUND

Selenium is an essential element of antioxidant properties. Lithium is widely used in medicine but its administration can cause numerous side effects including oxidative stress. The present study aimed at evaluating if sodium selenite could influence chosen anti- and pro-oxidant parameters in rats treated with lithium.

METHODS

The experiment was performed on four groups of Wistar rats: I (control) - treated with saline; II (Li) - treated with lithium (2.7 mgLi/kg b.w. as Li2CO3), III (Se) - treated with selenium (0.5 mgSe/kg b.w. as Na2SeO3), IV (Li+Se) - treated with Li2CO3 and Na2SeO3 together at the same doses as in group II and III, respectively. All treatments were performed by stomach tube for three weeks in form of water solutions. The following anti- and pro-oxidant parameters: total antioxidant status (TAS) value, catalase (CAT) activity, concentrations of ascorbic acid (AA) and malonyldialdehyde (MDA) in plasma as well as whole blood superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured.

RESULTS

Selenium given alone markedly enhanced whole blood GPx and diminished plasma CAT vs.

CONTROL

Lithium significantly decreased plasma CAT and slightly increased AA vs.

CONTROL

Selenium co-administration restored these parameters to the values observed in control animals. Furthermore, selenium co-administration significantly increased GPx in Li-treated rats. All other parameters (TAS, SOD and MDA) were not affected by lithium and/or selenium.

CONCLUSION

Further research seems to be warranted to decide if application of selenium as an adjuvant in lithium therapy is worth considering.

Impact of ozone exposure on the response to glucocorticoid in a mouse model of asthma: involvements of p38 MAPK and MKP-1

Background

Molecular mechanisms involved in the oxidative stress induced glucocorticoids insensitivity remain elusive. The mitogen-activated protein kinase phosphatase (MKP) 1 mediates a part of glucocorticoids action and can be modified by exogenous oxidants. Whether oxidant ozone (O₃) can affect the function of MKP-1 and hence blunt the response to corticotherapy is not clear.

Methods

Here we employed a murine model of asthma established with ovalbumin (OVA) sensitization and challenge to evaluate the influence of O₃ on the inhibitory effect of dexamethasone on AHR and airway inflammation, and by administration of SB239063, a selective p38 MAPK inhibitor, to explore the underlying involvements of the activation of p38 MAPK and the expression of MKP-1.

Results

Ozone exposure not only aggravated the pulmonary inflammation and AHR, but also decreased the inhibitory effects of dexamethasone, accompanied by the elevated oxidative stress, airway neutrophilia, enhanced phosphorylation of p38 MAPK, and upregulated expression of IL-17. Administration of SB239063 caused significant inhibition of the p38 MAPK phosphorylation, alleviation of the airway neutrophilia, and decrement of the ozone-induced IL-17 expression, and partly restored the ozone-impaired effects of dexamethasone. Ozone exposure not only decreased the protein expression of MKP-1, but also diminished the dexamethasone-mediated induction process of MKP-1 mRNA and protein expression.

Conclusions

The glucocorticoids insensitivity elicited by ozone exposure on current asthma model may involve the enhanced phosphorylation of p38 MAPK and disturbed expression of MKP-1.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0126-x) contains supplementary material, which is available to authorized users.

Hepatoprotective effects of phloridzin on hepatic fibrosis induced by carbon tetrachloride against oxidative stress-triggered damage and fibrosis in rats

The present study was to study the hepatoprotective effects of phloridzin (PHL) on hepatic fibrosis induced by carbon tetrachloride (CCl₄) in rats, on the basis of this investigation, the possible mechanism of PHL was elucidated. Male Sprague Dawley (SD) rats were randomly divided into six groups: control, model, PHL-L, PHL-M, PHL-H and colchine. All rats except control group were intraperitoneally injected with CCl₄, and control rats were injected with olive oil, twice a week for eight weeks. At the same time, the rats were orally given homologue drugs once a day, respectively. Hepatoprotective effects of PHL were evaluated by liver weight indexes, biochemical values, total antioxidant capacity and total-superoxide dismutase, histopathological observations, hepatic fibrosis, and the hepatic fibrosis relative gene and protein expressions. PHL significantly improved hepatic function; remarkably decreased serum hyaluronic acid (HA), transforming growth factor-β1 (TGF-β1), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and liver tissues hydroxyproline, malondialdehyde (MDA) levels, increased glutathione peroxidase (GSH-Px), total-antioxygen capacity (T-AOC) and total-superoxide dismutase (T-SOD) contents of liver tissues; Real-time polymerase chain reaction (PCR) and immunohisto-chemical results showed PHL might markedly reverse the up-regulated mRNA and protein expressions of the α-smooth muscle actin (SMA), TGF-β1 and tissue inhibitor of metalloproteinase-1 (TIMP1), up-regulate the matrix metalloproteinase-1 (MMP1) mRNA and protein expressions. Histopathological observations provided supportive evidence for biochemical analyses and the hepatic fibrosis relative gene and protein expressions, and with the dose of PHL increasing, the aforesaid improvement became more and more strong. The studies demonstrated that PHL exerted beneficially hepatoprotective effects on hepatic fibrosis induced by CCl₄, mainly enhancing antioxidant capacity of liver organizations, reduce the level of lipid peroxidation induced by CCl₄, and protect hepatocyte membranes from damage, and alleviate hepatic fibrosis.

Alteration of osteocalcin mRNA expression in ovine osteoblasts in dependence of sodium fluoride and sodium selenite medium supplementation

Objective of this study was to assess the quantification of osteocalcin (OCN) expression by ovine osteoblasts cultured with different concentrations of sodium fluoride (F) and sodium selenite (Se) to evaluate the interaction of these agents on OCN expression in vitro . We wanted to demonstrate a possible protective effect of selenium on the toxic effect of fluoride. Osteoblasts were isolated by complete trypsin and collagenase digestion from ovine calvarial bone and cultured in DMEM supplemented with 15% FBS at 37 degrees C in a humidified 5% CO 2 incubator. Identified osteoblasts were divided into one control group (C) and eight experimental groups, which were exposed to different concentrations of sodium fluoride (F; 0, 0.5, 1 mM) sodium selenite (Se; 0, 0.1, 1 microM). At different time points after treatment total RNA was extracted and reverse transcribed into first-strand cDNA. OCN mRNA was indirectly measured by real-time fluorescent quantitative PCR (qPCR). OCN mRNA expression in F 1 mM with Se 1 microM group was found to have a high peak at day seven and was lower before and afterwards. Expression of OCN mRNA in all groups except control could be promoted by F and/or Se showing a general upregulation. Furthermore, the toxicity from excessive exposure of osteoblast with F could be circumvented by usage of moderate concentration of Se. Osteoblasts cultured in vitro may have stressful responses to F and Se at the first few days. Low concentrations of Se inhibit the toxic effects of high concentrations of F. Therefore, F and Se could be used as antagonistic factors, which could regulate osteocalcin expression.