Marina Prigol

Convulsant effect of diphenyl diselenide in rats and mice and its relationship to plasma levels

Diphenyl diselenide [(PhSe)2], an organoselenium compound, presents pharmacological and toxicological properties in rodents. The aim of this study was to carry out the determination and quantification of (PhSe)2 in plasma after oral administration (p.o.) of this compound (500 mg/kg), dissolved in canola oil, in rats and mice. The second objective was to verify the involvement of different routes of administration ((p.o.), intraperitoneal (i.p.) and subcutaneous (s.c.)) and vehicle solutions (canola oil and dimethyl sulfoxide (DMSO)) in the appearance of seizure episodes and in the plasmatic levels of (PhSe)2 in rats and mice. Analysis of (PhSe)2 in blood samples was performed by gas chromatography/flame ionized detector system (GC/FID). Rat and mouse peak plasma (PhSe)2 levels were 13.13 and 10.11 microg/ml (C(max)), respectively, and occurred at 0.5h (T(max)) post-dosing. The use of different administration routes (p.o., i.p. and s.c.) and vehicle solutions (canola oil or DMSO) in rats and mice indicated that the appearance of seizures and (PhSe)2 plasmatic levels are dependent of administration routes (i.p.>p.o.>s.c.), vehicle solutions (DMSO>canola oil) and animal species (mice>rat).

Chronic unpredictable mild stress decreases BDNF and NGF levels and Na(+),K(+)-ATPase activity in the hippocampus and prefrontal cortex of mice: antidepressant effect of chrysin.

Our working hypothesis is that brain neurotrophins and brain Na(+),K(+)-ATPase may be strongly associated with the occurrence of depression in animals subjected to chronic unpredictable mild stress (CUMS). Still, we believe that chrysin, a natural and bioactive flavonoid found in honey and some plants, can provide satisfactory effects on antidepressant therapy. Thus, we aimed to evaluate the effect of CUMS on brain-derived neurotropic factor (BDNF) and nerve growth factor (NGF) levels as well as the Na(+),K(+)-ATPase activity in the hippocampus and prefrontal cortex of female mice. We also aimed to examine the effect of a 28-day oral treatment with chrysin (5 or 20mg/kg) in female mice subjected to CUMS, comparing to the effect of fluoxetine. Results showed that CUMS applied for 28days induced a decrease in BDNF and NGF levels as well as in the Na(+),K(+)-ATPase activity. CUMS also promoted a depressive status in the swimming forced test (FST), in the sucrose preference test, and in corticosterone levels. Chrysin (20mg/kg) and fluoxetine also occasioned the up-regulation of BDNF and NGF levels in non-stressed mice and in mice subjected to CUMS. CUMS decreased non-protein thiol (NPSH) levels and increased reactive oxygen species (ROS) levels. In response to these changes, the glutathione reductase (GR), glutathione peroxidase (GPx) and catalase (CAT) activities were increased in mice exposed to CUMS. Chrysin and fluoxetine treatments protected against all these alterations, suggesting the involvement of the antioxidant function in the antidepressant effect of chrysin and fluoxetine. In conclusion, CUMS decreased BDNF and NGF levels as well as the Na(+),K(+)-ATPase activity in mice. Chrysin presented antidepressant effect in mice on behavioral, neurotrophic and biochemistry parameters equivalent to fluoxetine. Furthermore, we suggest that the up-regulation of BDNF and NGF levels is a mechanism possibly involved in the antidepressant effect of chrysin in mice.

Involvement of oxidative stress in seizures induced by diphenyl diselenide in rat pups

In the present study the potential neurotoxicity of diphenyl diselenide, as measured by the manifestation of seizures in rat pups (postnatal days, PND, 12-14) was evaluated. The results suggest that the latency for the appearance of tonic-clonic seizures, characterized by rearing and falling of rat pups body, was dependent of the dose tested. Diphenyl diselenide at high doses induced seizure episodes in rat pups. The highest dose of diphenyl diselenide (500 mg/kg) increased the levels of lipid peroxidation and catalase activity as well as decreased delta-ALA-D (delta-aminolevulinate dehydratase) and Na(+), K(+) ATPase activity in the brain of rat pups. Our results indicate the possible involvement of free radical oxygen injury in diphenyl diselenide-induced seizures. The data obtained with the dose of 150 mg/kg in the brain of rats that exhibited seizures are: an increase in lipid peroxidation levels; the lack of effect on catalase activity; an inhibition of delta-ALA-D activity, supporting that the enzyme activity is more sensitive than other parameters analyzed as an indicator of oxidative stress. The lowest dose of diphenyl diselenide emphasizes the relationship between the appearance of seizures and the latency for the onset of the first episode. Taken together, this paper could add to our understanding of diphenyl diselenide neurotoxic effect demonstrated by the appearance of seizures which are, at least in part, related to the oxidative stress.

Antioxidant effect of diphenyl diselenide on oxidative stress caused by acute physical exercise in skeletal muscle and lungs of mice

This study was designed to examine if diphenyl diselenide (PhSe)2, an organoselenium compound, attenuates oxidative stress caused by acute physical exercise in skeletal muscle and lungs of mice. Swiss mice were pre‐treated with (PhSe)2 (5 mg kg‐1 day‐1) for 7 days. At the 7th day, the animals were submitted to acute physical exercise which consisted of continuous swimming for 20 min. The animals were euthanized 1 and 24 h after the exercise test. The levels of thiobarbituric acid reactive species (TBARS), non‐protein thiols (NPSH) and ascorbic acid and the activity of catalase (CAT) were measured in the lungs and skeletal muscle of mice. Glycogen content was determined in the skeletal muscle of mice. Parameters in plasma (urea and creatinine) were determined. The results demonstrated an increase in TBARS levels induced by acute physical exercise in the skeletal muscle and lungs of mice. Animals submitted to exercise showed an increase in non‐enzymatic antioxidant defenses (NPSH and ascorbic acid) in the skeletal muscle. In lungs of mice, activity of CAT was increased. (PhSe)2 protected against the increase in TBARS levels and ameliorated antioxidant defenses in the skeletal muscle and lungs of mice submitted to physical exercise. These results indicate that acute physical exercise caused a tissue‐specific oxidative stress in the skeletal muscle and lungs of mice. (PhSe)2 protected against oxidative damage induced by acute physical exercise in mice. Copyright

Protective effect of hesperidin in a model of Parkinson's disease induced by 6-hydroxydopamine in aged mice

OBJECTIVE Parkinsons disease (PD) may be caused by the interaction of a number of factors, including genetics, toxins, oxidative stress, mitochondrial abnormalities, and aging. Studies have shown that consumption of an antioxidant-rich diet may reduce the incidence of neurodegenerative diseases. The aim of this study was to evaluate the role of the flavonoid hesperidin in an animal model of PD induced by 6-hidroxidopamine (6-OHDA). METHODS Aged mice were treated with hesperidin (50 mg/kg) during 28 d after an intracerebroventricular injection of 6-OHDA. The enzymatic activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and glutathione S-transferase, the levels of glutathione, reactive oxygen species, total reactive antioxidant potential, dopamine and its levels of metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid, was analyzed in the striatum. The behavioral parameters (depressive-like, memory, and locomotor) were measured. RESULTS This study demonstrated that hesperidin (50 mg/kg) treatment was effective in preventing memory impairment in the Morris water maze test, as well as, depressive-like behavior in the tail suspension test. Hesperidin attenuated the 6-OHDA-induced reduction in glutathione peroxidase and catalase activity, total reactive antioxidant potential and the dopamine and its metabolite levels in the striatum of aged mice. 6-OHDA increased reactive oxygen species levels and glutathione reductase activity in the striatum, and these alterations were mitigated by chronic administration of hesperidin. CONCLUSION This study demonstrated a protective effect of hesperidin on the neurotoxicity induced by 6-OHDA in aged mice, indicating that it could be useful as a therapy for the treatment of PD.

Antidepressant-like effect of diphenyl diselenide on rats exposed to malathion: involvement of Na+K+ ATPase activity.

The antidepressant-like effect of repeated administration of diphenyl diselenide (PhSe)2 in rats exposed to malathion is reported. The role of Na+K+ ATPase, acetylcholinesterase (AChE) and monoamine oxidase (MAO) activities and oxidative stress in antidepressant behavior were investigated in cerebral cortex of rats. Rats were exposed once a day for 3 consecutive days to malathion (50mg/kg, intraperitoneal) and (PhSe)2 (50mg/kg, oral). To investigate the antidepressant-like behavior rats were submitted to the forced swimming test (FST) and open-field test (OFT). Thiobarbituric acid reactive species (TBARS) levels, enzymatic and non-enzymatic antioxidant defenses were carried out in cerebral cortex of rats. The results confirmed that malathion increased immobility time in the FST without altering the locomotor performance in the OFT. Treatment with (PhSe)2 ameliorated performance in the FST without altering the crossing numbers in the OFT. The inhibition of Na+K+ ATPase activity caused by malathion was prevented by treatment with (PhSe)2. Exposure to malathion did not alter parameters of oxidative stress as well as AChE and MAO activities in cerebral cortex of rats. In conclusion, (PhSe)2 exerted antidepressant-like effect in rats exposed to malathion. Na+K+ ATPase activity is, at least in part, involved in (PhSe)2 antidepressant-like behavior.

Hypolipidemic action of chrysin on Triton WR-1339-induced hyperlipidemia in female C57BL/6 mice

Chrysin (5,7-dihydroxyflavone) is a flavonoid, natural component of traditional medicinal herbs, present in honey, propolis and many plant extracts. The objective of this study was to investigate the hypolipidemic properties of chrysin on Triton WR-1339-induced hyperlipidemia in female C57BL/6 mice. Triton WR-1339 was administered intraperitoneally (400 mg/kg) to overnight-fasted mice to develop acute hyperlipidemia. Chrysin was administered orally (10 mg/kg) 30 min before Triton WR-1339. At 24 h after Triton WR-1339 injection, blood samples were collected to measure plasma lipid levels. The hepatic thiobarbituric acid reactive substances (TBARS), carbonyl content, non-protein sulfhydryl (NPSH) and ascorbic acid (AA) levels, as well as catalase (CAT) and superoxide dismutase (SOD) activity were recorded. Chrysin administration significantly decreased total cholesterol levels. In addition, it partially decreased non-high density lipoprotein-cholesterol and triglycerides levels in plasma of hyperlipidaemic mice. In addition chrysin administration prevented the increase on TBARS levels and prevented the decrease in SOD activity induced by Triton WR-1339. These findings indicated that chrysin was able to decrease plasma lipids concentration and that its antioxidant properties was, at least in part, involved in the hypolipidaemic action of chrysin.

Diphenyl diselenide ameliorates behavioral and oxidative parameters in an animal model of mania induced by ouabain.

Bipolar disorder (BD) is a common and severe mood disorder associated with higher rates of suicide and disability. Ouabain, a Na(+)/K(+)-ATPase inhibitor, induces behavioral changes in rats and has been used as a model of mania. The aim of this study was to investigate if diphenyl diselenide [(PhSe)(2)], an organoselenium compound with pharmacological properties, is effective against ouabain-induced hyperactivity and alterations in cerebral oxidative status of rats. Male Wistar rats were treated with a single dose of (PhSe)(2) (50 mg/kg, p.o.) 30 min before i.c.v. injection of ouabain (5 μl, 10(-5) M) or with the mood stabilizer, lithium chloride (LiCl) (45 mg/kg, p.o.), twice a day, for 7 days before the administration of ouabain. Open-field locomotion was quantified after ouabain administration. Thiobarbituric acid reactive substances (TBARS), oxidatively modified proteins, tyrosine nitration, ascorbic acid and non-protein thiols (NPSH) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities were determined in the whole brain. Ouabain increased locomotor activity in the open-field test and pretreatment with (PhSe)(2) or LiCl blocked this effect. In addition, ouabain increased lipid peroxidation and oxidatively modified proteins, demonstrated by a significant increase in TBARS levels and carbonyl content, which were attenuated by pretreatment with (PhSe)(2) or LiCl. The activities of SOD and CAT were increased by ouabain. LiCl was effective on preventing the increases of both enzyme activities, but (PhSe)(2) attenuated the ouabain effect in SOD activity. GPx and GR activities, ascorbic acid, NPSH and tyrosine nitration levels were not altered in all experimental groups. Similarly to LiCl, (PhSe)(2) produced an antimanic-like action, since it was effective against the locomotor hyperactivity elicited by ouabain. The results also indicated that (PhSe)(2) was effective against oxidative stress caused by ouabain in rats.

Protective effect of unsymmetrical dichalcogenide, a novel antioxidant agent, in vitro and an in vivo model of brain oxidative damage

Unsymmetrical dichalcogenides, a class of organoselenium compounds, were screened for antioxidant activity in rat brain homogenates in vitro. Unsymmetrical dichalcogenides (1-3) were tested against lipid peroxidation induced by sodium nitroprusside (SNP) or malonate, and reactive species (RS) production induced by sodium azide in rat brain homogenates. Compounds 1 (without a substituent at the phenyl group), 2 (chloro substituent at the phenyl group bounded to the sulfur atom) and 3 (chloro substituent at the phenyl group bounded to the selenium atom) protected against lipid peroxidation induced by SNP. The IC50 values followed the order 3<2<1. Lipid peroxidation induced by malonate was also reduced by dichalcogenides 1, 2 and 3. The IC50 values were 3<or=2<1. RS production induced by sodium azide was reduced by compounds 1-3 (IC50 values were 3<2<or=1). Compounds 1-3 were screened against oxidatively modified protein in rat brain homogenates. Compound 3 presented the lowest value of IC50 23.5 microM (IC50 values were 3<2<or=1). Compounds 1-3 at 40 microM displayed thiol peroxidase-like activity in rat brain homogenates. Since compound 3 was the most efficient antioxidant against lipid and protein oxidation in rat brain homogenates in vitro, 3 was investigated in the oxidative damage induced by SNP in mouse brain. Swiss albino mice were pre-treated with compound 3 (50 mg/kg, oral route, p.o). After 30 min, mice received SNP (0.35 microM/site i.c.v.). The levels of lipid peroxidation and the activity of catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) were carried out in brain homogenates of SNP-injected mice. Compound 3 protected against the increase in lipid peroxidation levels and the reduction of GST and GR activities in brain homogenate of mice exposed to SNP, suggesting the potential beneficial activity of dichalcogenides against deleterious oxidations in an in vivo model.

Involvement of the serotonergic system in the anxiolytic-like effect caused by m-trifluoromethyl-diphenyl diselenide in mice

The organoselenium compound diphenyl diselenide (PhSe)(2) has shown interesting antioxidant and neuroprotective activities. On the other hand, this compound has also presented some toxic effects. m-Trifluoromethyl-diphenyl diselenide (m-CF(3)-C(6)H(4)Se)(2), a structural analog of (PhSe)(2), has proven to be antipsychotic and antioxidant in mice. The present study was designed to investigate the anxiolytic-like effect of (m-CF(3)-C(6)H(4)Se)(2) in female mice, employing light/dark box and elevated plus-maze (EPM) tests. The involvement of 5-hydroxytryptamine (5-HT) receptors and monoamine oxidase (MAO) activity in the anxiolytic-like effect was also evaluated. (m-CF(3)-C(6)H(4)Se)(2) (0.1, 10 and 100 mg/kg, p.o.) did not affect locomotor activity as evaluated in the open-field test (OFT). (m-CF(3)-C(6)H(4)Se)(2) at the dose of 100 mg/kg produced an anxiolytic-like action, both in light-dark box and the EPM tests. To evaluate the role of 5-HT receptors in the anxiolytic-like effect of (m-CF(3)-C(6)H(4)Se)(2), a selective 5-HT(1A) receptor antagonist, WAY100635 (0.1 mg/kg, s.c.), a non-selective 5-HT(2A/2C) receptor antagonist, ritanserin (2 mg/kg, i.p.) and a selective 5-HT(3) receptor antagonist, ondansetron (0.1 mg/kg, i.p.) were used. All the antagonists used were able to abolish the anxiolytic-like effect of (m-CF(3)-C(6)H(4)Se)(2). (m-CF(3)-C(6)H(4)Se)(2), at the dose of 100 mg/kg, inhibited the MAO-A activity in mice brain. Taken together these data demonstrated that the anxiolytic-like effect caused by (m-CF(3)-C(6)H(4)Se)(2) seems to be mediated by the involvement of the serotonergic system.