Mitochondrial function and cellular energy maintenance during aging in a Drosophila melanogaster model of Parkinson disease.

Parkinson's disease (PD) is a common neurodegenerative disease characterized by movement disorders as well as loss of dopaminergic neurons. Moreover, genes affecting mitochondrial function, such as SNCA, Parkin, PINK1, DJ-1 and LRRK2, were demonstrated to be associated with PD and other neurodegenerative disease. Additionally, mitochondrial dysfunction and cellular energy imbalance are common markers found in PD. In this study, we used the pink1 null mutants of Drosophila melanogaster as a Parkinson's disease model to investigate how the energetic pathways and mitochondrial functions change during aging in a PD model. In our study, the loss of the pink1 gene decreased the survival percent and the decreased climbing index during aging in pink1-/- flies. Furthermore, there was an impairment in mitochondrial function demonstrated by a decrease in OXPHOS CI&CII-Linked and ETS CI&CII-Linked in pink1-/- flies at 3, 15 and 30 days of life. Interestingly, OXPHOS CII-Linked and ETS CII-Linked presented decreases only at 15 days of life in pink1-/- flies. Moreover, there was an increase in peroxide (H2O2) levels in pink1-/- flies at 15 and 30 days of life. Loss of the pink1 gene also decreased the activity of citrate synthase (CS) and increased the activity of lactate dehydrogenase (LDH) in pink1-/- flies head. Our results demonstrate a metabolic shift in ATP production in pink1-/- flies, which changed from oxidative to glycolytic pathways from 15 days of age, and is apparently more pronounced in the central nervous system.

Cyclophosphamide in Drosophila promotes genes and transposable elements differential expression and mitochondrial dysfunction.

Cyclophosphamide (CPA) is an alkylating agent used for cancer chemotherapy, organ transplantation, and autoimmune disease treatment. Here, mRNA sequencing and high-resolution respirometry were performed to evaluate the alterations of Drosophila melanogaster gene expression fed with CPA under acute (0.1 mg/mL, for 24 h) and chronic (0.05 mg/mL, for 35 days) treatments. Differential expression analysis was performed using Cufflinks-Cuffdiff, DESeq2, and edgeR software. CPA affected genes are involved in several biological functions, including stress response and immune-related pathways, oxi-reduction and apoptotic processes, and cuticle and vitelline membrane formation. In particular, this is the first report of CPA-induced mitochondrial dysfunction caused by the downregulation of genes involved with mitochondria constituents. CPA treatment also changed the transcription pattern of transposable elements (TEs) from the gypsy and copia superfamilies. The results presented here provided evidence of CPA mitochondrial toxicity mechanisms and that CPA can modify TEs transcription in Drosophila flies.

Influence of diphenyl diselenide on chlorpyrifos-induced toxicity in Drosophila melanogaster.

Exposure to chlorpyrifos (CPF) poses several harmful effects to human and animal health. The present study investigated the influence of diphenyl diselenide (DPDS) on CPF-induced toxicity in Drosophila melanogaster. Firstly, the time course lethality response of virgin flies (2- to 3-day-old) to CPF (0.075-0.6µg/g) and DPDP (5-40µmol/kg) in the diet for 28 consecutive days were investigated. Subsequently, the protective effect of DPDS (10, 20 and 40µmol/kg) on CPF (0.15µg/g)-induced mortality, locomotor deficits, neurotoxicity and oxidative stress was assessed in a co-exposure paradigm for 7 days. Results showed that CPF exposure significantly decreased the percent live flies in a time- and concentration-dependent manner, whereas the percent live flies with DPDS treatment was not statistically different from control following 28 days of treatment. In the co-exposure study, CPF significantly increased flies mortality while the survivors exhibited significant locomotor deficits with decreased acetylcholinesterase (AChE) activity. Dietary supplementation with DPDS was associated with marked decrease in mortality, improvement in locomotor activity and restoration of AChE activity in CPF-exposed flies. Moreover, CPF exposure significantly decreased catalase and glutathione-S-transferase activities, total thiol level with concomitant significant elevation in the levels of reactive oxygen species and thiobarbituric acid reactive substances in the head and body regions of the treated flies. Dietary supplementation with DPDS significantly improved the antioxidant status and prevented CPF-induced oxidative stress, thus demonstrating the protective effect of DPDS in CPF-treated flies.

Cryotherapy reduces skeletal muscle damage after ischemia/reperfusion in rats.

The aim of this study was to analyze the effects of cryotherapy on the biochemical and morphological changes in ischemic and reperfused (I/R) gastrocnemius muscle of rats. Forty male Wistar rats were divided into control and I/R groups, and divided based on whether or not the rats were submitted to cryotherapy. Following the reperfusion period, biochemical and morphological analyses were performed. Following cryotherapy, a reduction in thiobarbituric acid-reactive substances and dichlorofluorescein oxidation levels were observed in I/R muscle. Cryotherapy in I/R muscle also minimized effects such as decreased cellular viability, levels of non-protein thiols and calcium ATPase activity as well as increased catalase activity. Cryotherapy also limited mitochondrial dysfunction and decreased the presence of neutrophils in I/R muscle, an effect that was corroborated by reduced myeloperoxidase activity in I/R muscle treated with cryotherapy. The effects of cryotherapy are associated with a reduction in the intensity of the inflammatory response and also with a decrease in mitochondrial dysfunction.

Antioxidant properties of diorganoyl diselenides and ditellurides: modulation by organic aryl or naphthyl moiety.

Diorganoyl dichalcogenide compouds can have antioxidant activity in different in vitro and in vivo models. Here, we have compared the potential antioxidant activity of 1-dinaphthyl diselenide (1-NapSe)(2), 2-dinaphthyl diselenide (2-NapSe)(2), 1-dinaphthyl distelluride (1-NapTe)(2), 2-dinaphthyl ditelluride (2-NapTe)(2) with their well-studied analogs diphenyl diselenide ((PhSe)(2)) and diphenyl telluride ((PhTe)(2)). (PhSe)(2), (PhTe)(2), and naphthalene analogs-inhibited Fe(II)-induced lipid peroxidation, catalytically decomposed hydrogen peroxide and oxidized thiols, such as dithiothreitol (DTT), Cysteine (CYS), dimercaptopropionic acid (DMPS), and thiophenol (PhSH). (PhSe)(2) was the less potent of the tested compounds against Fe(II)-induced lipid peroxidation in brain homogenates and the change in the organic moiety from an aryl to naphthyl group increased considerably the antioxidant potency of diselenide compounds. However, the change from aryl to naphthyl had little effect on the thio-peroxidase-like activity of diorganoyl dichalcogenides. These results suggest that minor changes in the organic moiety of aromatic diselenide compounds can modify profoundly their capacity to inhibit iron-induced lipid peroxidation. The pharmacological properties of organochalcogens are thought to be linked to their capacity of modulating oxidative stress. Consequently, it becomes important to explore the toxicological properties of dinaphthyl diselenides and ditellurides.

Behavior and brain enzymatic changes after long-term intoxication with cadmium salt or contaminated potatoes.

This study investigated the cadmium (Cd) intoxication on cognitive, motor and anxiety performance of rats subjected to long-term exposure to diet with Cd salt or with Cd from contaminated potato tubers. Potato plantlets were micropropagated in MS medium and transplanted to plastic trays containing sand. Tubers were collected, planted in sand boxes and cultivated with 0 or 10 µM Cd and, after were oven-dried, powder processed and used for diet. Rats were divided into six groups and fed different diets for 5 months: control, potato, potato+Cd, 1, 5 or 25 mg/kg CdCl2. Cd exposure increased Cd concentration in brain regions. There was a significant decrease in the step-down latency in Cd-intoxicated rats and, elevated plus maze task revealed an anxiolytic effect in rats fed potato diet per se, and an anxiogenic effect in rats fed 25 mg/kg Cd. The brain structures of rats exposed to Cd salt or Cd from tubers showed an increased AChE activity, but Na+,K+-ATPase decreased in cortex, hypothalamus, and cerebellum. Therefore, we suggest an association between the long-term diet of potato tuber and a clear anxiolytic effect. Moreover, we observed an impaired cognition and enhanced anxiety-like behavior displayed by Cd-intoxicated rats coupled with a marked increase of brain Cd concentration, and increase and decrease of AChE and Na+,K+-ATPase activities, respectively.

Resveratrol reduces vacuous chewing movements induced by acute treatment with fluphenazine.

Treatment with classical neuroleptics in humans can produce a serious side effect, known as tardive dyskinesia (TD). Here, we examined the possible neuroprotective effects of resveratrol, a polyphenol compound contained in red grapes and red wine, in an animal model of orofacial dyskinesia (OD) induced by acute treatment with fluphenazine. Adult male rats were treated during 3 weeks with fluphenazine enantate (25 mg/kg, i.m., single administration) and/or resveratrol (1 mg/kg, s.c., 3 times a week). Vacuous chewing movements (VCMs), locomotor and exploratory performance were evaluated. Fluphenazine treatment produced VCM in 70% of rats and the concomitant treatment with resveratrol decreased the prevalence to 30%, but did not modify the intensity of VCMs. Furthermore, the fluphenazine administration reduced the locomotor and exploratory activity of animals in the open field test. Resveratrol co-treatment was able to protect the reduction of both parameters. Taken together, our data suggest that resveratrol could be considered a potential neuroprotective agent by reducing motor disorders induced by fluphenazine treatment.

Ascorbic acid oxidation of thiol groups from dithiotreitol is mediated by its conversion to dehydroascorbic acid.

The aim of the present study was to investigate whether the in vitro pro-oxidant effect of ascorbic acid towards thiol groups could be mediated by free radicals formed during its auto-oxidation and/or by a direct oxidation of -SH groups by its oxidized form (dehydroascorbic acid). This hypothesis was examined by measuring the rate of AA (ascorbic acid) oxidation in MOPS (3-morpholinepropanesulfonic acid buffer) and phosphate buffer (PB). Here we have used dithiothreitol (DTT) as model of vicinal thiol-containing enzymes, namely δ-aminolevulinate dehydratase. The rate of AA and DTT oxidation was more pronounced in the presence of PB than in the MOPS. AA oxidation induced by iron/EDTA complex was significantly reduced by addition of superoxide dismutase, catalase and DTT to the reaction medium. H2O2 alone did not stimulate the oxidation of AA; however, AA oxidation was enhanced significantly with the addition of crescent concentrations of iron. Conversely, in DTT oxidation assay (without AA) the addition of iron, EDTA and H2O2, did not promote the oxidation of -SH groups. Our findings suggest that in the presence of physiological concentrations of AA and thiols, the oxidation of -SH groups is mediated by AA conversion to dehydroascorbic acid with the participation of iron. Furthermore, free radical species formed during the auto-oxidation of AA apparently did not oxidize thiol groups to a significant extent.

Inhibition of δ-aminolevulinate dehydratase is not closely related to the development of hyperglycemia in alloxan-induced diabetic mice.

Alloxan is a compound widely used in models of diabetes mellitus due to its ability for damage insulin-producing ß-cells. The aim of this study was to investigate acute (after 24h) and sub-acute (after seven days) effects of 200mg/kg alloxan administration on mice. Biochemical parameters as liver, kidney, and blood δ-ALA-D activity, total sulfhydryl content of hepatic and renal tissues, and hepatic and renal content of malondialdehyde (MDA) were evaluated. The histopathology of hepatic and renal tissues of alloxan-treated and control animals was carried out. Further, blood glucose levels were determined in an attempt to correlate alloxan-induced hyperglycemia with changes in thiol status. Results showed that mice exhibited a significant inhibition of hepatic and renal δ-ALA-D activity in addition to a significant decrease in total sulfhydryl groups of same tissues in both acute and sub-acute alloxan administrations. Moreover, alloxan-induced inhibition of δ-ALA-D activity was partly suppressed when enzymatic assay was performed in the presence of dithiothreitol, suggesting that inhibitory effect of alloxan on δ-ALA-D activity is, at least partially, related to the oxidation of the enzyme's essential thiol groups. Blood δ-ALA-D activity was significantly inhibited only 24h after alloxan administration; however, at this time, a hyperglycemic status was not observed in animals. In contrast, a significant increase in blood glucose levels was observed seven days after alloxan administration. Despite of alterations in biochemical parameters, histological tissue examination of alloxan-treated mice revealed typical renal and hepatic parenchyma. Therefore, these results showed that acute toxic effects of alloxan are related, at least partially, to depletion of sulfhydryl groups, and do not closely relate to the development of hyperglycemia in mice.

Evaluation of the biological effects of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate, a new telluroamino acid derivative of aspartic acid.

(S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate, a new telluroamino acid derivative, showed remarkable glutathione peroxidase (GPx)-like activity, attesting to its antioxidant potential. However, the stability and toxicity of this compound has not yet been investigated. The present study was designed to investigate the pharmacological/toxicological properties of this compound in vitro and in vivo. In vitro, this telluroamino acid derivative significantly blocked spontaneous and Fe(II)-induced TBARS formation in rat brain homogenates, demonstrating high antioxidant activity. In addition, it exhibited GPx-like and thiol oxidase activities. However, when subcutaneously administered to mice, (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate indicated genotoxic and mutagenic effect in adult male mice. Considering the differential effects of (S)-dimethyl 2-(3-(phenyltellanyl) propanamido) succinate in vitro and in vivo, additional experiments are needed to elucidate the mechanism(s) by which this compound displays its antioxidant/toxicological effects.

Dexmedetomidine protects blood δ-aminolevulinate dehydratase from inactivation caused by hyperoxygenation in total intravenous anesthesia.

Delta-aminolevulinate dehydratase (δ-ALA-D) enzyme is sensitive to pro-oxidant agents, including molecular oxygen. Here, we tested whether hyperoxygenation after total intravenous (i.v.) anesthesia could interact with the type of anesthesia (dexmedetomidine, continuous infusion; 0.5 µg/kg/h or remifentanil, continuous infusion; 0.3 µg/kg/min) plus propofol using blood δ-ALA-D activity and thiobarbituric acid reactive substances (TBARS) levels as ending points of toxicity. In absence or presence of dithiothreitol (DTT), δ-ALA-D activity was reduced after hyperoxygenation in the group treated with remifentanil and was not modified in dexmedetomidine group. TBARS increased considerably in the blood of both groups of patients after oxygenation. The results obtained here suggest that the hyperoxygenation was associated with a marked increase in TBARS production regardless of the type of anesthesia. δ-ALA-D activity was only inhibited in remifentanil group, which indicates a possible interaction between oxygenation and the type of anesthetic. This is the first demonstration that dexmedetomidine may protect blood δ-ALA-D from oxidation. However, further studies are necessary to establish a possible antioxidant role of dexmedetomidine against hyperoxygenation in human blood.

Evidence of the involvement of K+ channels and PPARgamma receptors in the antidepressant-like activity of diphenyl diselenide in mice.

OBJECTIVES: This study investigated the involvement of different types of K(+) channels and PPARgamma receptors in the antidepressant-like effect of diphenyl diselenide in mice. METHODS: Mice were pretreated with subeffective doses of K(+) channel inhibitors (tetraethylammonium, glibenclamide, charybdotoxin and apamin), openers (cromakalim, minoxidil), GW 9662 (a PPARgamma antagonist) or vehicle. Thirty minutes later the mice received diphenyl diselenide in either an effective or a subeffective dose, 30 min before a tail-suspension test. KEY FINDINGS: Pre-treatment with tetraethylammonium, charybdotoxin or apamin combined with a subeffective dose of diphenyl diselenide was effective in decreasing the immobility time in the mouse tail-suspension test. The reduction in the immobility time elicited by an effective dose of diphenyl diselenide in this test was prevented by the pretreatment of mice with minoxidil and GW 9662. CONCLUSIONS: Diphenyl diselenide elicited an antidepressant-like effect and this action was mediated, at least in part, by modulation of K(+) channels and PPARgamma receptors.

Diphenyl diselenide protects against glycerol-induced renal damage in rats.

In this study we evaluated the effect of diphenyl diselenide (PhSe)(2) on glycerol-induced acute renal failure in rats. Rats were pre-treated by gavage every day with (PhSe)(2 )(7.14 mg kg(-1)) for 7 days. On the eighth day, rats received an intramuscular injection of glycerol (8 mL kg(-1)). Twenty-four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), delta-aminolevulinate dehydratase (delta-ALA-D) and Na(+), K(+)-ATPase activities and ascorbic acid levels were evaluated in renal homogenates. Histopathological evaluations were also performed. The results demonstrated that (PhSe)(2) was able to protect against the increase in urea and creatinine levels and histological alterations in kidney induced by glycerol. (PhSe)(2) protected against the inhibition in delta-ALA-D, CAT and GPx activities and the reduction in ascorbic acid levels induced by glycerol in kidneys of rats. In conclusion, the present results indicate that (PhSe)(2) was effective in protecting against acute renal failure induced by glycerol.

Involvement of different types of potassium channels in the antidepressant-like effect of tramadol in the mouse forced swimming test.

Administration of tramadol elicited an antidepressant-like effect in the rat forced swimming test (FST) by a mechanism dependent on the inhibition of the L-arginine-nitric oxide (NO)-guanylate cyclase pathway. Since it has been reported that NO can activate different types of potassium (K(+)) channels in several tissues, the present study investigated the possibility of synergistic interactions between different types of K(+) channel inhibitors and tramadol in the mouse FST. Intracerebroventricular pretreatment of mice with tetraethylammonium (TEA, a non-specific inhibitor of K(+) channels, 25 pg/site), glibenclamide (an ATP-sensitive K(+) channel inhibitor, 0.5 pg/site) or charybdotoxin (a large- and intermediate conductance calcium-activated K(+) channel inhibitor, 25 pg/site) was able to produce a synergistic action of a subeffective dose of tramadol (1 mg/kg, p.o.). Conversely, pretreatment with apamin (a small-conductance calcium-activated K(+) channel inhibitor, 10 pg/site) did not modify the action of a subeffective dose of tramadol (1 mg/kg, p.o.). Administration of tramadol and the K(+) channel inhibitors, alone or in combination, did not affect the number of crossings and rearings in the open field test (OFT). Reduction in the immobility time elicited by an active dose of tramadol (40 mg/kg, p.o.) in the FST was prevented by pretreatment of mice with cromakalim (a K(+) channel opener, 10 microg/site, i.c.v.), without affecting the number of crossings and rearings in the OFT. Thus, our findings clearly suggest that oral acute administration of tramadol produces antidepressant-like effect on the FST in mice by a mechanism that involves the K(+) channels.

Guanosine and synthetic organoselenium compounds modulate methylmercury-induced oxidative stress in rat brain cortical slices: involvement of oxidative stress and glutamatergic system.

Excessive formation of reactive oxygen species (ROS) and disruption of glutamate uptake have been pointed as two key mechanisms in methylmercury-toxicity. Thus, here we investigate the involvement of glutamatergic system in methylmercury (MeHg) neurotoxicity and whether diphenyl diselenide, ebselen and guanosine could protect cortical rat brain slices from MeHg-induced ROS generation. MeHg (100 and 200 microM) increased 2',7'-dichlorodihydrofluorescin (DCFH) oxidation after 2h of exposure. At 50 microM, MeHg increased DCFH oxidation only after 5h of exposure. Guanosine (1 and 5 microM) did not caused any effect per se; however, it blocked the increase in DCFH caused by 200 or 50 microM MeHg. Ebselen (5 and 10 microM) decreased significantly the DCFH oxidation after 2 and 5h of exposure to MeHg. Diphenyl diselenide (5 microM) did not change the basal DCFH oxidation, but abolished the pro-oxidant effect of MeHg. MK-801 also abolished the pro-oxidant effect of MeHg. These results demonstrate for the first time the potential antioxidant properties of organoseleniun compounds and guanosine against MeHg-induced ROS generation after short-term exposure in a simple in vitro model. In conclusion, endogenous purine (guanosine) and two synthetic organoselenium compounds can modulate the pro-oxidant effect of MeHg in cortical brain slices.

Comparative studies on dicholesteroyl diselenide and diphenyl diselenide as antioxidant agents and their effect on the activities of Na+/K+ ATPase and delta-aminolevulinic acid dehydratase in the rat brain.

The present study sought to evaluate the effect of a newly synthesized selenium compound, dicholesteroyl diselenide (DCDS) and diphenyl diselenide (DPDS) on the activities of delta-aminolevulinate dehydratase and Na+/K+-ATPase in the rat brain. The glutathione peroxidase mimetic activity of the two compounds as well as their ability to oxidize mono- and di- thiols were also evaluated. The antioxidant effects were tested by measuring the ability of the compounds to inhibit the formation of thiobarbituric acid reactive species and also their ability to inhibit the formation of protein carbonyls. The results show that DPDS exhibited a higher glutathione peroxidase mimetic activity as well as increased ability to oxidize di-thiols than DCDS. In addition, while DPDS inhibited the formation of thiobarbituric acid reactive species and protein carbonyls, DCDS exhibited a prooxidant effect in all the concentration range (20-167 microM) tested. Also the activities of cerebral delta-aminolevulinate dehydratase and Na+/K+ ATPase were significantly inhibited by DPDS but not by DCDS. In addition, the present results suggested that the inhibition of Na+/K+ ATPase by organodiselenides, possibly involves the modification of the thiol group at the ATP binding site of the enzyme. In conclusion, the results of the present investigation indicated that the non-selenium moiety of the organochalcogens can have a profound effect on their antioxidant activity and also in their reactivity towards SH groups from low-molecular weight molecules and from brain proteins.

Highly stereoselective one-pot procedure to prepare bis- and tris-chalcogenide alkenes via addition of disulfides and diselenides to terminal alkynes.

We present here the reaction of diorganoyl dichalcogenides with terminal alkynes under catalyst-free conditions, by a one-pot procedure, to prepare bis- and tris-chalcogenide alkenes selectively, avoiding the previous preparation of chalcogen alkynes. The reaction proceeded cleanly under mild reaction conditions, and the addition of dichalcogenides to alkynes occurred stereoselectively to give exclusively the corresponding Z isomers. We observed that the selectivity control was governed by the effective participation of the hydroxyl group from propargyl alcohols. In addition, the bis-chalcogenide alkenes were exclusively obtained with propargyl alcohol having the acidic hydroxyl group proton. Conversely, the alkynes with no potentially acidic hydroxyl group proton, at propargyl positions, gave exclusively the tris-chalcogenide alkenes.