p-Chloro-diphenyl diselenide attenuates plasma lipid profile changes and hepatotoxicity induced by nonionic surfactant tyloxapol in rats.

Tyloxapol is a nonionic surfactant oligomer inductor of dyslipidemia, which in turn is a risk factor for liver damage. Selenium-based compounds have emerged as promising therapeutic candidates for treating different experimental disorders. This study investigated the effects of p-chloro-diphenyl diselenide (p-ClPhSe)2 on toxicity induced by Tyloxapol in rats. Plasma lipid profile, hepatic functionality and oxidative stress parameters were evaluated in adult male Wistar rats treated with (p-ClPhSe)2 (10 mg/kg; oral administration by gavage) for seven days and exposed to a single Tyloxapol injection (400 mg/kg; intraperitoneal route) 30 min after the last (p-ClPhSe)2 treatment. Tyloxapol exposure increased the plasma levels of total cholesterol, triacylglycerol, non-HDL-cholesterol and the calculated cardiac risk index (CRI). The plasma activities of alanine and aspartate aminotransferase (ALT and AST, liver function markers) were increased in rats exposed to Tyloxapol, which demonstrates a hepatic lipotoxicity. In the liver, reactive oxygen species (ROS) content was enhanced and the non-protein sulfhydryl (NPSH) levels were decreased by Tyloxapol. The data revealed that repeated treatment with (p-ClPhSe)2 reduced plasma lipid alterations and hepatotoxicity induced by Tyloxapol. Although (p-ClPhSe)2 did not reduce ROS levels increased by Tyloxapol, it increased NPSH content in the liver. Pearson's correlation coefficient revealed a positive relationship between the levels of hepatic NPSH and plasma HDL. HDL is known by eliciting antioxidant activity; therefore, the improvement in HDL function could be suggested as a therapeutic target. In conclusion, the results demonstrate the protective effects of (p-ClPhSe)2 on the hepatic lipotoxicity induced by Tyloxapol in rats.

Monosodium glutamate induced nociception and oxidative stress dependent on time of administration, age of rats and susceptibility of spinal cord and brain regions.

Monosodium glutamate (MSG), a food flavor enhancer used worldwide, has been studied because it may cause neurotoxicity, which is associated with oxidative stress. The aim of this study was to investigate whether spinal cord and brain regions are affected by oxidative stress and the temporal profile of nociceptive responses induced by MSG in newborn and adult rats. The newborn (post natal day, PND 1) Wistar rats received ten subcutaneous injections of MSG (4.0 g/kg) or saline solution. At PND 3, 11 or 90, the rats performed nociceptive tests and parameters of oxidative stress were evaluated in samples of spinal cord and brain regions. Adult rats (PND 90) were injected with MSG (4.0 g/kg, 10 injections) or saline solution, but MSG did not induce nociception or oxidative stress. The neonatal administration of MSG increased nociceptive behavior in the tail immersion, hot plate and formalin tests and decreased the SOD activity in spinal cord of PND 3 rats. In rats at PND 11 and 90, the neonatal administration of MSG increased mechanical allodynia and nociceptive behavior in the hot plate and formalin tests. The neonatal administration of MSG induced oxidative stress in the hippocampus of rats at PND 11 and in the cerebral cortex at PND 90. These findings demonstrate that nociception and oxidative stress was induced in rats dependent on the time of MSG administration, susceptibility of spinal cord and brain regions and the age of rats.

High doses of 2,2'-dithienyl diselenide cause systemic toxicity in rats: an in vitro and in vivo study.

Organoselenium compounds have important pharmacological properties. However, these compounds can cause toxicity, typically related to oxidation of endogenous thiols. The aim of this study was to investigate whether 2,2'-dithienyl diselenide (DTDS) has potential toxicity in vitro and in vivo. Therefore, sulfhydryl-containing enzyme activities, δ-aminolevulinic acid dehydratase (δ-ALA-D) and Na(+) -K(+) -ATPase were used to predict DTDS toxicity in rat brain homogenate in vitro. In in vivo experiments, a DTDS administration (50 or 100 mg kg(-1) , p.o.) to rats was performed and toxicological parameters were determined. DTDS inhibited δ-ALA-D (IC50 2 µm) and Na(+) -K(+) -ATPase (IC50 17 µm) activities in vitro. The inhibitory effect of DTDS on δ-ALA-D and Na(+) -K(+) -ATPase activities was restored by dithiothreitol. DTDS (5-25 µm) elicited a thiol oxidase-like activity. In vivo, DTDS (50 and 100 mg kg(-1) ) caused systemic toxicity, evidenced by a decrease in water and food intakes and body weight gain, as well as the death of rats. DTDS at the dose of 100 mg kg(-1) increased plasma alanine and aspartate aminotransferase activities and decreased urea levels. At 50 and 100 mg kg(-1) , it increased lipid peroxidation levels. At the highest dose, DTDS inhibited δ-ALA-D activity. By contrast, Na(+) -K(+) -ATPase activity and antioxidant defense were not altered in the brains of rats exposed to DTDS. In conclusion, interaction with the cisteinyl residues seems to mediate the inhibitory effect of DTDS on sulfhydryl-containing enzymes in vitro. In addition, high oral doses of DTDS induce toxicity in rats.

Diphenyl diselenide is as effective as Ebselen in a juvenile rat model of cisplatin-induced nephrotoxicity.

BACKGROUND: Cisplatin (CIS) is widely used in the chemotreatment of pediatric tumors. However, the CIS use is limited because of its high incidence of toxicity, mainly nephrotoxicity. Although there are many studies about CIS-related nephrotoxicity in animal models, only a few studies focus on juvenile animals. Because redox disturbances have been associated with kidney damage induced by CIS, this study aimed to compare the effectiveness of Ebselen and diphenyl diselenide (PhSe)2 against nephrotoxicity induced by CIS in juvenile rats. METHODS: Juvenile Wistar rats were randomly divided into six groups: rats from groups I to III received an intraperitoneal (i.p.) injection with saline solution. The other groups received CIS (i.p., 6 mg/kg) on the first day. One hour before CIS injection and on the next four days, animals of groups III and V were intragastrically treated with Ebselen (11 mg/kg) whereas those from groups IV and VI received (PhSe)2 (12 mg/kg). After 24 h of the last treatment, blood and kidney were collected, and the parameters of renal function and oxidative stress were determined. RESULTS: Kidney damage induced by CIS was confirmed by the increase of creatinine, urea and uric acid levels in the blood of juvenile rats. The renal oxidative disturbance was characterized by an increase in the levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl, and nitrogen oxides (Nox), as well as the decrease in non-protein thiol content (NPSH), glutathione-S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) activities. CIS inhibited the activities of δ-aminolevulinic acid dehydratase (δ-ALA-D) and Na+, K+-ATPase and down-regulated the Nrf2/Keap-1/HO-1 pathway in the kidney of juvenile rats. CONCLUSION: Both Ebselen and (PhSe)2 modulated back to the normal levels all parameters altered by the CIS administration in the kidney of juvenile rats. Thus, this study shows that (PhSe)2 was as effective as Ebselen in protecting the kidney against oxidative damage caused by CIS in rats.

Pattern differences between newborn and adult rats in cisplatin-induced hepatorenal toxicity.

Although cisplatin (CIS) has been associated with serious adverse effects, such as hepatotoxicity and nephrotoxicity in adult rats, there is few reports on its use in newborn rats. The aim of this study was to evaluate acute toxic effects of CIS in newborn rats. Adult and newborn Wistar rats received CIS by the i. p. route, at the dose of 5 or 10 mg/kg. After 24 h of treatment, blood, kidney, and liver were excised from the animals and parameters of renal and hepatic functions, oxidative stress markers were determined. Acute administration of CIS caused an increase of AST activity and urea levels, suggesting hepatorenal toxicity in newborn and adult rats. However, the pattern and intensity of damage was different between ages and tissues. Newborn rats showed more pronouncedly oxidative stress damage, characterized by an increase in reactive species and protein carbonyl levels, lower NPSH content and highest inhibition in δ-ALA-D and CAT activities. Besides that, it was observed a faster molecular response in protein levels involved with apoptosis and oxidative stress response; whereas in the beginning the damage was less severe in the kidney than in the liver of adult rats. Thus, the present study shows that there are body response differences between adult and newborn rats to CIS acute exposure being that newborn rats are more susceptible than adults.

Effectiveness of bis(phenylimidazoselenazolyl) diselenide on a mouse model of inflammatory nociception.

The injection of complete Freund's adjuvant (CFA) in the hindpaw of rodents induces tissue inflammation and nociceptive hypersensitivity. In addition, it has been reported that organoselenium compounds have antinociceptive properties in animal models. The purpose of this study was to investigate the potential antinociceptive effect of bis(phenylimidazoselenazolyl) diselenide (BPIS) in the inflammatory nociception model in mice and its possible mechanism of action. C57BL/6 mice received CFA intraplantar in right hindpaw and the inflammatory response was verified 24h after injection as well as the antinociceptive effect of BPIS. The CFA-induced mechanical allodynia was reversed by BPIS treatment (1mg/kg, p.o.) observed through the von Frey hair test. Additionally, L-arginine (600mg/kg; i.p.), administered before BPIS treatment, blocked its antinociceptive effect. Regarding myeloperoxidase activity, NOx and 3-nitrotyrosine levels, BPIS administration did not reverse alterations observed in the paw of animals injected with CFA. BPIS reversed the increase in spinal NOx content induced by CFA. In the spinal cord, it was also found that CFA induced an increase in malondialdehyde content and a decrease in glutamate uptake, and these alterations were reversed by BPIS. Moreover, BPIS treatment induced an increase in non-protein thiol levels in spinal cord of animals that received CFA injection. No alterations were found in glutathione peroxidase, reductase and S-transferase activities of experimental groups. The obtained data reinforce the relevance of BPIS as an antinociceptive agent as well as highlight the importance of the nitric oxide pathway in the spinal cord and its antioxidant potential for its mechanism of action.

Biochemical and histological evaluations of anti-inflammatory and antioxidant p-chloro-selenosteroid actions in acute murine models of inflammation.

This study investigated the potential p-chloro-selenosteroid (PCS) anti-inflammatory effect in different animal models of acute inflammation. In order to determine a time- and a dose-curve response of action, female adult Swiss mice (25-35g) were divided in different groups and pretreated by the intragastric route (i.g.) with PCS (5-10mg/kg) and after the specific times (5, 30 and 60min) the ear inflammation was induced with croton oil (2.5%, 20µl). The ear edema, myeloperoxidase (MPO) activity and histological analyses were performed. In a second experiment, the pleurisy model was used to determine the PCS protective effect (10mg/kg, i.g., 30min before induction) in the inflammatory and oxidative alterations induced by an intrapleural injection of a 1% carrageenan solution (0.1ml) in exudate and lung samples. Dexamethasone (1mg/kg, i.g.) was used as positive control for both models. Statistical analysis was performed through a One-Way ANOVA test followed by the Newman-Keuls' test. Pretreatment of 30min with PCS, only at a dose of 10mg/kg, decreased ear edema and the MPO activity as well as the histological alterations induced by croton oil. In the pleurisy model, PCS (10mg/kg, i.g.; 30min) reduced the leukocyte counts, histological alterations, MPO and adenosine deaminase activities, oxidative damage and the non-enzymatic antioxidant defense imbalance. PCS had a similar anti-inflammatory profile to dexamethasone; however, it showed a better antioxidant effect. PCS had anti-inflammatory and antioxidant actions in two well established inflammation models in mice.

Bis(phenylimidazoselenazolyl) diselenide as an antioxidant compound: An in vitro and in vivo study.

The organoselenium compounds have been reported for many biological properties, especially as potent antioxidants. The compound bis(phenylimidazoselenazolyl) diselenide (BPIS) is a novel diaryl diselenide derivative, which shows antinociceptive and anti-inflammatory properties in mice, but whose antioxidant activity has not been studied. The present study aimed to investigate the antioxidant and toxicological potential of BPIS in brain of rats in vitro, and the effect of BPIS against the oxidative damage induced by sodium nitroprusside (SNP) in mouse brain. BPIS, at low molecular range, reduced lipid peroxidation (LP) and protein carbonyl (PC) content in rat brain homogenates (IC50 values of 1.35 and 0.74 µM, respectively). BPIS also presented dehydroascorbate reductase-like and glutathione-S-transferase-like, as well as DPPH and NO-scavenging activities. Related to togicological assays, BPIS inhibited δ-ALA-D and Na(+), K(+)-ATPase activities in rat brain homogenates and [(3)H]glutamate uptake in synaptosomes in vitro, but these effects were observed at higher concentrations than it had antioxidant effect (IC50 values of 16.41, 26.44 and 3.29 µM, respectively). In vivo, brains of mice treated with SNP (0.335 µmol per site; i.c.v.) showed an increase in LP and PC and a reduction in non protein thiol content, however, it was not observed significant alterations in antioxidant enzyme activities. BPIS (10 mg/kg; p.o.) protected against these alterations caused by SNP. In conclusion, the results demonstrated the antioxidant action of BPIS in in vitro assays. Furthermore, BPIS protected against oxidative damage caused by SNP in mouse brain, strengthening the potential antioxidant effect of this compound.

Evaluation of the pharmacological properties of salicylic acid-derivative organoselenium: 2-hydroxy-5-selenocyanatobenzoic acid as an anti-inflammatory and antinociceptive compound.

The present study evaluated the antinociceptive and anti-inflammatory effects of per oral (p.o.) administration of salicylic acid-derivative organoselenium compounds in chemical models of nociception in mice. The compounds (50 mg/kg; p.o.) were administered 30 and 60 min before the nociceptive behavior and compared to the positive-control, acetylsalicylic acid (ASA; 200 mg/kg; p.o.). In addition, a dose-response curve (25-100 mg/kg) for compounds was carried out in the formalin test. When assessed in the chemical models, acetic acid-induced writhing behavior, formalin and glutamate tests, the compounds showed the following antinociceptive profile 1B>2B>1A>2A, suggesting a chemical structure-dependent relationship. Then, the anti-inflammatory properties and toxicological potential of compound 1B were investigated. Compound 1B, similar to the positive-control, ASA, diminished the edema formation and decreased the myeloperoxidase activity induced by croton oil (2.5%) in the ear tissue. The results also indicate that a single oral administration of 1B caused neither signs of acute toxicity nor those of gastrointestinal injury. The administration of 1B did not alter the water and food intakes, plasma alanine and aspartate aminotransferase activities or urea levels and cerebral or hepatic δ-aminolevulinate dehydratase activity. Salicylic acid-derivative organoseleniums, mainly compound 1B, have been found to be novel compounds with antinociceptive/anti-inflammatory properties; nevertheless, more studies are required to examine their therapeutic potential for pain treatment.