Harmine prevents 3-nitropropionic acid-induced neurotoxicity in rats via enhancing NRF2-mediated signaling: Involvement of p21 and AMPK.

Oxidative stress induced neurotoxicity is increasingly perceived as an important neuropathologic mechanism underlying the motor and behavioral phenotypes associated with Huntington's disease (HD). Repeated exposure to 3-nitropropionic acid (3-NP) induces neurotoxic changes which closely simulate the neuropathological and behavioral characteristics of HD. This study aimed at evaluating the prophylactic effects of the dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) inhibitor "harmine" against 3-NP-indued neurotoxicity and HD-like symptoms. The potential prophylactic effect of harmine (10 mg/kg/day; intraperitoneal) was investigated on 3-NP-induced motor and cognitive HD-like deficits, nuclear factor erythroid 2 like 2 (NRF2), AMP kinase (AMPK) and p21 protein levels and the gene expression of haem oxygenase-1 (Ho-1), NAD(P)H: quinone oxidoreductase-1 (Nqo-1) and p62 in addition to redox imbalance and histological neurotoxic changes in the striatum, prefrontal cortex, and hippocampus of male Wistar rats. Harmine successfully increased the protein levels of NRF2, AMPK and p21 and the gene expression of Ho-1, Nqo-1 and p62, restored redox homeostasis, and reduced CASPASE-3 level. This was reflected in attenuation of 3-NP-induced neurodegenerative changes and improvement of rats' motor and cognitive performance. This study draws attention to the protective role of harmine against 3-NP-induced motor and cognitive dysfunction that could be mediated via enhancing NRF2-mediated signaling with subsequent amelioration of oxidative stress injury via NRF2 activators, p21 and AMPK, in the striatum, prefrontal cortex, and hippocampus which could offer a promising therapeutic tool to slow the progression of HD.

Reduced mitochondrial complex II activity enhances cell death via intracellular reactive oxygen species in STHdhQ111 striatal neurons with mutant huntingtin.

Huntington's disease (HD) is an inherited neurodegenerative disorder caused by CAG repeat expansion in the huntingtin (HTT) gene. Here, we examined the effects of antioxidants on 3-nitropropionic acid (3-NP; a mitochondrial complex II inhibitor)-induced mitochondrial dysfunction and cell death in STHdhQ111 striatal cells carrying homozygous mutant HTT with extended CAG repeats compared with those in STHdhQ7 striatal cells. 3-NP reduced cell viability and increased cell death both in STHdhQ111 and STHdhQ7, and the cytotoxicity was markedly attenuated by antioxidants (N-acetyl-l-cysteine and edaravone). Furthermore, 3-NP increased intracellular reactive oxygen species (ROS) production in both cell lines, and this increase was inhibited by antioxidants. Mitochondrial ROS was also increased by 3-NP in STHdhQ111 but not in STHdhQ7, and this increase was significantly inhibited by edaravone. Mitochondrial membrane potential (MMP) was lower in STHdhQ111 than that in STHdhQ7, and antioxidants prevented 3-NP-induced MMP decrease in STHdhQ111.3-NP enhanced oligomerization of dynamin-related protein 1 (Drp1), a protein that promotes mitochondrial fission in both cells, and both antioxidants prevented the increase in oligomerization. These results suggest that reduced mitochondrial complex II activity enhances cell death via intracellular ROS production and Drp1 oligomerization in striatal cells with mutant HTT and antioxidants may reduce striatal cell death.

Neuroprotective effects of the CTK 01512-2 toxin against neurotoxicity induced by 3-nitropropionic acid in rats.

The mitochondrial inhibitor 3-nitropropionic acid (3-NP) induces excitotoxicity. The authors hypothesized that CTK 01512-2, a recombinant peptide calcium channel N-type blocker, and the TRPA1 antagonist, could show neuroprotective effects. The male Wistar rats received 3-NP [25 mg/kg (i.p.) for 7 days], and a treatment of CTK 01512-2 was delivered intrathecally (i.t.), thrice a week. The neuroprotective effects were evaluated by [18F]FDG MicroPET analysis. The CTK 01512-2 toxin was able to reestablish similar glucose uptakes on the control animals. To detect the neurobehavioral effects from 3-NP, three protocols (6.25, 12.5, 18.75 mg/kg of 3-NP (i.p.), for 3, 4, and 6 days, respectively) were evaluated by performance tests (open field test, walk footprint, elevated plus-maze, Y-maze, and the object recognition test). Important disabilities in the gait of the rats were seen, as well as memory deficits, and anxious behavior in the animals that were treated with all 3-NP protocols. The dose of 18.75 mg/kg (for 3 days) showed the most pronounced behavioral effects and lethality, while the rats treated with 12.5 mg/kg (for 4 days) showed behavioral effects similar to the 6.25 mg/kg dose (for 6 days). The third protocol was then repeated and the rats were treated with the CTK 01512-2 toxin to be evaluated behaviorally again. The recombinant peptide prevented all of the gait-evaluated parameters that were induced by 3-NP at a 6.25 mg/kg dose, which displayed an improvement in the exploratory activities. Overall, these results have reinforced the positive effects of CTK 01512-2 against the behavioral changes that were induced by the mitochondrial inhibitor 3-NP.

Folic acid increases levels of GHS in brain of rats with oxidative stress induced with 3-nitropropionic acid.

Aim: This study tested the hypothesis that folic acid (FA) modulates biogenic amines and protects the brain against oxidative stress induced by 3-nitropropionic acid (3NPA).Methods: Male Wistar rats received (groups of six) for 5 d: FA (50 mg/kg); 3NPA (10 mg/kg); or FA +3NPA. At last day, rats were sacrificed, and their brain was obtained to measure the levels of dopamine, 5-hydroxiindol acetic acid (5-HIAA). Reduced glutathione (GSH), total ATPase, H2O2 and lipid peroxidation were measured.Results: GSH increased significantly in cortex of rats treated with FA. ATPase increased significantly in cerebellum/medulla oblongata and decreased in cortex of animal treated with 3NPA. 5-HIAA increased in striatum of rats that received 3NPA alone or combined with FA.Conclusion: 3NPA generates free radicals such effect can be counteracted with FA administration since this folate increases antioxidant capacity and modulates biogenic amines.

24-epibrassinolide stimulates imidacloprid detoxification by modulating the gene expression of Brassica juncea L.

BACKGROUND: Pesticides cause oxidative stress to plants and their residues persist in plant parts, which are a major concern for the environment as well as human health. Brassinosteroids (BRs) are known to protect plants from abiotic stress conditions including pesticide toxicity. The present study demonstrated the effects of seed-soaking with 24-epibrassinolide (EBR) on physiological responses of 10-day old Brassica juncea seedlings grown under imidacloprid (IMI) toxicity. RESULTS: In the seedlings raised from EBR-treated seeds and grown under IMI toxicity, the contents of hydrogen peroxide (H2O2) and superoxide anion (O.2-) were decreased, accompanied by enhanced activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST), guaiacol peroxidase (POD) and the content of glutathione (GSH). As compared to controls, the gene expressions of SOD, CAT, GR, POD, NADH (NADH-ubiquinone oxidoreductase), CXE (carboxylesterase), GSH-S (glutathione synthase), GSH-T (glutathione transporter-1), P450 (cytochrome P450 monooxygenase) and GST1-3,5-6 were enhanced in the seedlings raised from EBR-treated seeds and grown in IMI supplemented substratum. However, expression of RBO (respiratory burst oxidase, the gene responsible for H2O2 production) was decreased in seedlings raised from EBR treated seeds and grown under IMI toxicity. Further, the EBR seed treatment decreased IMI residues by more than 38% in B. juncea seedlings. CONCLUSIONS: The present study revealed that EBR seed soaking can efficiently reduce oxidative stress and IMI residues by modulating the gene expression of B. juncea under IMI stress. In conclusion, exogenous EBR application can protect plants from pesticide phytotoxicity.

Pomegranate seed oil: Effect on 3-nitropropionic acid-induced neurotoxicity in PC12 cells and elucidation of unsaturated fatty acids composition.

BACKGROUND: Seed oils are used as cosmetics or topical treatment for wounds, allergy, dandruff, and other purposes. Natural antioxidants from plants were recently reported to delay the onset or progress of various neurodegenerative conditions. Over one thousand cultivars of Punica granatum (Punicaceae) are known and some are traditionally used to treat various ailments. AIM: The effect of pomegranate oil on 3-nitropropionic acid- (3-NP) induced cytotoxicity in rat pheochromocytoma (PC12) neuronal cells was analyzed in this study. Furthermore, the analysis of unsaturated fatty acid composition of the seed oil of pomegranate by gas chromatography-electron impact mass spectrometry (GC-MS) was done. RESULTS: GC-MS study showed the presence of 6,9-octadecadiynoic acid (C18:2(6,9)) as a major component (60%) as 4,4-dimethyloxazoline derivative. The total extractable oil with light petroleum ether by Soxhlet from the dry seed of P. granatum was 4-6%. The oil analyzed for 48.90 ±â€Š1.50 mg gallic acid equivalents/g of oil, and demonstrated radical-scavenging-linked antioxidant activities in various in vitro assays like the DPPH (2,2-diphenyl-l-picrylhydrazyl, % IP = 35.2 ± 0.9%), ABTS (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), % IP 2.2 ± 0.1%), and ß-carotene bleaching assay (% IP = 26 ± 3%), respectively, which could be due the possible role of one methylene interrupted diynoic acid system for its radical-scavenging/antioxidant properties of oil. The oil also reduced lipid peroxidation, suppressed reactive oxygen species, extracellular nitric oxide, lactate/pyruvate ratio, and lactase dehydrogenase generated by 3-NP- (100 mM) induced neurotoxicity in PC12 cells, and enhanced the levels of enzymatic and non-enzymatic antioxidants at 40 µg of gallic acid equivalents. CONCLUSION: The protective effect of pomegranate seed oil might be due to the ability of an oil to neutralize ROS or enhance the expression of antioxidant gene and the exact mechanism of action yet to be elucidated.

Effect of rutin against a mitochondrial toxin, 3-nitropropionicacid induced biochemical, behavioral and histological alterations-a pilot study on Huntington's disease model in rats.

Dietary compounds like flavonoids may offer protection against neurodegeneration. Huntington's disease (HD) is a neurodegenerative disorder characterized by symptoms like chorea and dementia. 3-Nitropropionic acid (3-NP), a Succinate dehydrogenase (SDH) inhibitor produces behavioral, biochemical and histological changes in the striatum, mimics HD in animals and humans. The present study was designed to examine the protective activity of Rutin (RT), a primary flavonoid from citrus fruits, green tea on 3-NP induced experimental model of HD in rats. Rats were pretreated with Rutin, a potent antioxidant (25 and 50 mg/kg b.w.) orally prior to the intraperitoneally (i.p.) administration of 3-NP (10 mg/kg b.w.) for 14 days. Behavioral assessments were carried out on 5th, 10th and 15th day after 3-NP treatment. Body weight, biochemical and histological studies were analyzed on 15th day. Systemic administration of 3-NP significantly reduced the body weight, locomotor activities (Rota rod, Open field test), memory (Morris water maze) and antioxidants such as Glutathione (GSH) levels, activities of Superoxide dismutase (SOD), Catalase (CAT), Glutathione peroxidase (GPx), Glutathione-S-transferase (GST), Glutathione reductase (GR). 3-NP also produces striatal damage by increased the levels of lipid peroxides, nitrite, Glial Fibrillary Acidic Protein (GFAP) and activity of Acetylcholine esterase (AchE). Thus, Rutin treatment of 25 and 50 mg/kg b.w. has significantly restored all the biochemical, behavioral and histological alterations caused by the 3-NP through its antioxidant activity. The findings of our study indicates that Rutin may have an important role in protecting the striatum from oxidative/nitrosative insults caused by 3-NP. These results suggest that RT might be a drug of choice to treat HD.

Copper disrupts S-nitrosothiol signaling in activated BV2 microglia.

Microglia, the primary resident immune cells of the central nervous system (CNS), responds rapidly to pathogens and injury by secreting immune mediators including nitric oxide (NO). The reaction of NO with the anti-oxidant glutathione forms S-nitrosoglutathione (GSNO), the major pool of biologic NO in the body. GSNO is degraded by GSNO reductase (GSNOR). Recently, we have shown that copper (Cu(I)) inhibits the release of NO in lipopolysaccharide (LPS)-stimulated BV2 microglia and induces BV2 microglia to acquire a mixed a profile with both pro- and anti-inflammatory characteristics. Since GSNOR is the critical enzyme in GSNO metabolism, we sought to determine whether Cu(I) affects GSNOR activity and S-nitrosothiol (SNO) accumulation in activated BV2 microglia. Our results show that GSNOR protein expression is reduced by Cu(I) treatment in LPS-stimulated BV2 microglia. Our results also show a decrease in S-nitrosothiol content despite a reduced GSNOR expression. This effect is most likely due to Cu(I) reacting with the central thiol of the SNO bond resulting in the degradation of SNO. A dose of 1 µM Cu(I) did not affect SNO protein accumulation in LPS-stimulated BV2 microglia, however, a dose of 100 µM Cu(I) inhibited SNO protein in accordance with inhibition of S-nitrosothiols. These data provide direct evidence that Cu(I) disrupts S-nitrosothiol homeostasis and NO metabolism, and, thus, provide new insights into the mechanisms involved in microglia-mediated-CNS disorders.

Organoselenium bis selenide attenuates 3-nitropropionic acid-induced neurotoxicity in rats.

This study was designed to evaluate the effects of bis selenide on Huntington disease (HD)-like signs induced by 3-nitropropionic acid (3-NP) in rats. To this aim, rats were treated for 4 days with bis selenide (5 or 20 mg/kg/day, per oral) 30 min before 3-NP (20 mg/kg/day, intraperitoneally). The body weight gain, locomotor activity, motor coordination, and biochemical parameters in striatal preparations were assessed 24 h after the last injection of 3-NP. The highest dose of bis selenide was effective in protecting against body weight loss and motor coordination deficit induced by 3-NP. The impairment of locomotor activity caused by 3-NP was abolished by bis selenide at both doses. Bis selenide (5 and 20 mg/kg) partially restored succinate dehydrogenase activity inhibited after 3-NP exposure. The dose of 20 mg/kg of bis selenide recovered partially δ-aminolevulinic acid dehydratase activity, and totally Na(+), K(+)-ATPase activity, two sulfhydryl enzymes sensitive to oxidizing agents, which had their activities inhibited by 3-NP. Also, 3-NP led to an increase in protein carbonyl levels and glutathione reductase activity and inhibited catalase activity-alterations that were reversed by bis selenide administration at both doses. The highest dose of bis selenide was effective against the increase of RS levels, the depletion of reduced glutathione content, and the inhibition of glutathione peroxidase activity induced by 3-NP. Bis selenide was not effective against inhibition of SOD activity caused by 3-NP. These findings demonstrate that bis selenide elicited protective effects against HD-like signs induced by 3-NP in rats.

c-Jun-dependent sulfiredoxin induction mediates BDNF protection against mitochondrial inhibition in rat cortical neurons.

In current study, we tested the hypothesis that c-Jun-dependent sulfiredoxin expression mediates protective effects of brain-derived neurotrophic factor (BDNF) against neurotoxicity induced by 3-nitropropionic acid (3-NP), a mitochondrial complex II inhibitor, in primary rat cortical cultures. We found that BDNF-dependent c-Jun expression and nuclear translocation required prior phosphorylation of extracellular signal-regulated kinase (ERK)1/2, but not Akt. BDNF also transiently activated the expression of sulfiredoxin, an ATP-dependent antioxidant enzyme, at both mRNA and protein levels. Furthermore, both c-Jun siRNA and ERK1/2 inhibitor PD98059 suppressed BDNF-induced sulfiredoxin expression. Finally, PD98059, c-Jun siRNA, and sulfiredoxin siRNA all abrogated BDNF-mediated 3-NP resistance. Together, these results established a signaling cascade of "BDNF → ERK1/2-Pi → c-Jun → sulfiredoxin → 3-NP resistance". We therefore conclude that c-Jun-induced sulfiredoxin mediates the BDNF-dependent neuroprotective effects against 3-NP toxicity in primary rat cortical neurons, at least in part.

Neuromodulatory propensity of Bacopa monnieri leaf extract against 3-nitropropionic acid-induced oxidative stress: in vitro and in vivo evidences.

We previously reported the propensity of Bacopa monnieri (BM) leaf powder to modulate endogenous levels of oxidative stress markers in the brain of prepubertal mice. In this study, we tested the hypothesis that pretreatment with an alcoholic extract of BM (BME) could provide neuroprotection against 3-nitropropionic acid (3-NPA)-induced oxidative stress under in vitro and in vivo conditions. In chemical systems, BME exhibited multiple free radical scavenging ability. Further, BME pretreatment completely abolished 3-NPA-induced oxidative stress response in brain (striatum, St) mitochondria in vitro. Likewise, pretreatment of dopaminergic (N27 cell lines) cells with BME not only abrogated the generation of reactive oxygen species (ROS) levels, but also offered marked protection against 3-NPA-mediated cytotoxicity. These findings were further validated employing a 3-NPA mice model in vivo. We determined the degree of oxidative stress induction, redox status, enzymic antioxidants, protein oxidation, and cholinergic function in various brain regions of male mice provided with BME for 10 days (prophylaxis) followed by 3-NPA challenge (75 mg/kg bw/day, i.p.). BME prophylaxis completely prevented 3-NPA-induced oxidative dysfunctions in St and other brain regions. 3-NPA-induced robust elevation of oxidative markers (malondialdehyde levels, ROS generation, hydroperoxide levels and protein carbonyls) in cytosol of brain regions was predominantly abolished among mice given BME prophylaxis. Interestingly, BME prophylaxis also prevented the depletion of reduced glutathione, thiol levels, and perturbations in antioxidant enzymes caused by 3-NPA. Collectively these findings provide evidence on the significant prophylactic neuroprotective efficacy of BME in prepubertal mice brain. Based on these data, it is hypothesized that BME can serve as a useful adjuvant in protecting brain against oxidative-mediated neurodegenerative disorders involving oxidative stress conditions.

The effect of Ginkgo biloba extract on 3-nitropropionic acid-induced neurotoxicity in rats.

3-Nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase enzyme (SDH), induces neurodegeneration similar to that observed in Huntington's disease (HD). Reduction of prepulse inhibition (PPI) of acoustic startle response, locomotor hypoactivity, bilateral striatal lesions as well as brain oxidative stress are major features of HD. The present study was designed to investigate neuroprotective effect of Ginkgo biloba extract (EGb 761) on 3-NP induced neurobehavioral changes and striatal lesions. Rats administered 3-NP (20mg/kg, s.c.) for five consecutive days exhibited PPI deficits and locomotor hypoactivity whereas, pretreatment of animals with EGb 761 (100mg/kg, i.p. for 15 days) ahead of and during the induction of HD by 3-NP (20mg/kg for 5 days starting at day 8) ameliorated 3-NP-induced neurobehavioral deficits. Administration of 3-NP increased the level of striatal malondialdehyde (MDA). This effect was prevented in animals pre-treated with EGb 761. Changes in the level of apoptotic regulatory gene expressions, following 3-NP treatment, were demonstrated as both an up-regulation and a down-regulation of the expression levels of striatal Bax and Bcl-xl genes, respectively. In addition, an up-regulation of the expression level of striatal glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also observed. Pre-treatment with EGb 761 caused a down-regulation in striatal GAPDH and Bax together with an up-regulation of striatal Bcl-xl expression level as compared to the 3-NP treated group. Histochemical examination of striatal tissue showed that EGb 761 significantly prevented 3-NP induced inhibition of SDH activity. Histopathological examination further affirmed the neuroprotective effect of EGb 761 against 3-NP toxicity. Taken together, these results suggest that EGb 761 has a neuroprotective role in the current HD paradigm, which may be related to improvement of energy metabolism, antioxidant properties and antiapoptotic effects.

On the antioxidant properties of kynurenic acid: free radical scavenging activity and inhibition of oxidative stress.

Kynurenic acid (KYNA) is an endogenous metabolite of the kynurenine pathway for tryptophan degradation and an antagonist of both N-methyl-D-aspartate (NMDA) and alpha-7 nicotinic acetylcholine (α7nACh) receptors. KYNA has also been shown to scavenge hydroxyl radicals (OH) under controlled conditions of free radical production. In this work we evaluated the ability of KYNA to scavenge superoxide anion (O(2)(-)) and peroxynitrite (ONOO(-)). The scavenging ability of KYNA (expressed as IC(50) values) was as follows: OH=O(2)(-)>ONOO(-). In parallel, the antiperoxidative and scavenging capacities of KYNA (0-150 µM) were tested in cerebellum and forebrain homogenates exposed to 5 µM FeSO(4) and 2.5 mM 3-nitropropionic acid (3-NPA). Both FeSO(4) and 3-NPA increased lipid peroxidation (LP) and ROS formation in a significant manner in these preparations, whereas KYNA significantly reduced these markers. Reactive oxygen species (ROS) formation were determined in the presence of FeSO(4) and/or KYNA (0-100 µM), both at intra and extracellular levels. An increase in ROS formation was induced by FeSO(4) in forebrain and cerebellum in a time-dependent manner, and KYNA reduced this effect in a concentration-dependent manner. To further know whether the effect of KYNA on oxidative stress is independent of NMDA and nicotinic receptors, we also tested KYNA (0-100 µM) in a biological preparation free of these receptors - defolliculated Xenopus laevis oocytes - incubated with FeSO(4) for 1 h. A 3-fold increase in LP and a 2-fold increase in ROS formation were seen after exposure to FeSO(4), whereas KYNA attenuated these effects in a concentration-dependent manner. In addition, the in vivo formation of OH evoked by an acute infusion of FeSO(4) (100 µM) in the rat striatum was estimated by microdialysis and challenged by a topic infusion of KYNA (1 µM). FeSO(4) increased the striatal OH production, while KYNA mitigated this effect. Altogether, these data strongly suggest that KYNA, in addition to be a well-known antagonist acting on nicotinic and NMDA receptors, can be considered as a potential endogenous antioxidant.

NR2B subunit blockade does not affect motor symptoms induced by 3-nitropropionic acid.

Broad-spectrum N-methyl D-aspartate (NMDA) antagonists, although proposed in therapies for several pathologies including Huntington's disease (HD), can produce dramatic side-effects. Thus, the therapeutic potential of subunit selective NMDA receptor antagonists warrants investigation. Overactivation of NMDA receptors containing the NR2B subunit plays a pathogenic role in HD, suggesting a neuroprotective potential of selective NR2B blockade. In the present study, we investigated whether the selective NR2B receptor antagonist, R-(R*,S*)-alpha-(4-hydroxyphenyl)-beta-methyl-4-(phenylmethyl)-1-piperidinepropanol, could also affect motor symptoms in mice intoxicated with 3-nitropropionic acid (3-NP), a phenotypic model of HD. NR2B subunit acute blockade had no effect on spontaneous activity, HD-like symptoms (clinical scale), and sensorimotor performances (beam task) in 3-NP intoxicated mice. These results suggest that selective NR2B antagonism has no acute symptomatic effect on motor and sensorimotor impairments due to 3-NP-induced striatal injury.

Neuroprotective effects of creatine.

There is a substantial body of literature, which has demonstrated that creatine has neuroprotective effects both in vitro and in vivo. Creatine can protect against excitotoxicity as well as against ß-amyloid toxicity in vitro. We carried out studies examining the efficacy of creatine as a neuroprotective agent in vivo. We demonstrated that creatine can protect against excitotoxic lesions produced by N-methyl-D: -aspartate. We also showed that creatine is neuroprotective against lesions produced by the toxins malonate and 3-nitropropionic acid (3-NP) which are reversible and irreversible inhibitors of succinate dehydrogenase, respectively. Creatine produced dose-dependent neuroprotective effects against MPTP toxicity reducing the loss of dopamine within the striatum and the loss of dopaminergic neurons in the substantia nigra. We carried out a number of studies of the neuroprotective effects of creatine in transgenic mouse models of neurodegenerative diseases. We demonstrated that creatine produced an extension of survival, improved motor performance, and a reduction in loss of motor neurons in a transgenic mouse model of amyotrophic lateral sclerosis (ALS). Creatine produced an extension of survival, as well as improved motor function, and a reduction in striatal atrophy in the R6/2 and the N-171-82Q transgenic mouse models of Huntington's disease (HD), even when its administration was delayed until the onset of disease symptoms. We recently examined the neuroprotective effects of a combination of coenzyme Q10 (CoQ10) with creatine against both MPTP and 3-NP toxicity. We found that the combination of CoQ and creatine together produced additive neuroprotective effects in a chronic MPTP model, and it blocked the development of alpha-synuclein aggregates. In the 3-NP model of HD, CoQ and creatine produced additive neuroprotective effects against the size of the striatal lesions. In the R6/2 transgenic mouse model of HD, the combination of CoQ and creatine produced additive effects on improving survival. Creatine may stabilize mitochondrial creatine kinase, and prevent activation of the mitochondrial permeability transition. Creatine, however, was still neuroprotective in mice, which were deficient in mitochondrial creatine kinase. Administration of creatine increases the brain levels of creatine and phosphocreatine. Due to its neuroprotective effects, creatine is now in clinical trials for the treatment of Parkinson's disease (PD) and HD. A phase 2 futility trial in PD showed approximately a 50% improvement in Unified Parkinson's Disease Rating Scale at one year, and the compound was judged to be non futile. Creatine is now in a phase III clinical trial being carried out by the NET PD consortium. Creatine reduced plasma levels of 8-hydroxy-2-deoxyguanosine in HD patients phase II trial and was well-tolerated. Creatine is now being studied in a phase III clinical trial in HD, the CREST trial. Creatine, therefore, shows great promise in the treatment of a variety of neurodegenerative diseases.

Lycopene prevents 3-nitropropionic acid-induced mitochondrial oxidative stress and dysfunctions in nervous system.

3-nitropropionic acid (3-NP), an irreversible inhibitor of succinic acid dehydrogenase (SDH), induces neurodegeneration similar to that observed in Huntington's disease (HD). The present study was designed to investigate neuroprotective effect of lycopene on 3-NP induced mitochondrial dysfunctions and oxidative stress. Rats administered with 3-NP (25 mg/kg, intraperitoneally) for four consecutive days exhibited deficits in cognitive and motor functions on day 15, whereas, lycopene (10 mg/kg, orally) administration for 15 days ameliorated 3-NP-induced neurobehavioral deficits. The activities of mitochondrial Complexes-II, IV and V were found to be significantly lowered in striatum along with the reduction in mitochondrial respiration. However, no significant change in Complex-I activity was observed in 3-NP treated animals. 3-NP administration increased the rate of reactive oxygen species (ROS) and nitrite production which was accompanied by increase in lipid peroxidation in mitochondria. Thiol content and superoxide dismutase activity were depressed in 3-NP treated brain. 3-NP treatment induced mitochondrial swelling with increased cytochrome c release. Expression of p53 and active caspase-3 were increased in 3-NP treated animals. On the other hand, lycopene administration exhibited protective effect on 3-NP induced mitochondrial dysfunctions and oxidative stress. The results of the present study provide evidence for effectiveness of lycopene in preventing mitochondrial dysfunctions in 3-NP-induced HD.

Neuroprotective mechanisms of brain-derived neurotrophic factor against 3-nitropropionic acid toxicity: therapeutic implications for Huntington's disease.

3-Nitropropionic acid (3-NP) is an irreversible inhibitor of mitochondrial succinate dehydrogenase that has been used to explore the molecular mechanisms of cell death associated with mitochondrial dysfunction and neurodegeneration for Huntington's disease (HD). Brain-derived neurotrophic factor (BDNF) is a neurotrophin that may regulate neuronal survival and differentiation. Experimental evidence derived from both clinical as well as basic research suggests a close association between BDNF deficiency and HD pathogenesis. In this review, we focus on recent progress in the molecular mechanisms responsible for the BDNF-mediated neuroprotective effects against mitochondrial dysfunction induced by 3-NP. Delineation of BDNF-mediated neuroprotective actions against 3-NP toxicity may add in the development of therapeutic intervention for HD where mitochondrial dysfunction is known to play a crucial role in pathogenesis of this devastating disease.

Erythropoietin and sonic hedgehog mediate the neuroprotective effects of brain-derived neurotrophic factor against mitochondrial inhibition.

Brain-derived neurotrophic factor (BDNF) deficiency and mitochondrial dysfunction have been implicated in the pathogenesis of Huntington's disease (HD). 3-Nitropropionic acid (3-NP) is a mitochondrial inhibitor commonly used as a pharmacological model mimicking HD. We have recently reported that preconditioning of primary rat cortical cultures with BDNF induces sonic hedgehog (SHH), which contributes to the protective effects of BDNF against 3-NP neurotoxicity. Because carbamylated erythropoietin (EPO) may induce SHH, we investigated whether BDNF-dependent SHH expression and 3-NP resistance require prior induction of EPO. We found that BDNF induced EPO expression at both mRNA and protein levels. BDNF-mediated SHH induction and 3-NP resistance were abolished by the soluble EPO receptor (sEPO-R), an EPO inhibitor. Recombinant rat EPO (rEPO) induced SHH and attenuated 3-NP neurotoxicity. The rEPO-dependent neuroprotection was suppressed by the SHH inhibitor cyclopamine (CPM); however, sEPO-R failed to affect SHH neuroprotection. Furthermore, the rEPO-dependent neuroprotection was not suppressed by the BDNF neutralizing antibody, which completely abolished BDNF-mediated 3-NP resistance at the same dosage. Overall, our results demonstrate that BDNF-dependent SHH expression and 3-NP resistance require prior induction of EPO, thus establishing a signaling cascade of "BDNF-->EPO-->SHH-->3-NP resistance" in rat cortical neurons.

Trolox ameliorates 3-nitropropionic acid-induced neurotoxicity in rats.

3-nitropropionic acid (3-NPA) is a naturally occurring neurotoxin produced by legumes of the genus Astragalus and Arthrium fungi. Acute exposure to 3-NPA results in striatal astrocytic death and variety of behavior dysfunction in rats. Oxidative stress has been reported to play an important role in 3-NPA-induced neurotoxicity. Trolox is a potent free radical chain breaking antioxidant which has been shown to restore structure and function of the nervous system following oxidative stress. This rapid and efficient antioxidant property of trolox was attributed to its enhanced water solubility as compared with alpha-tocopherol. This investigation was aimed to study the effect of trolox against 3-NPA-induced neurotoxicity in female Wistar rats. The animals received trolox (0, 40 mg, 80 mg and 160 mg/kg, orally) daily for 7 days. 3-NPA (25mg/kg, i.p.) was administered daily 30 min after trolox for the same duration. One additional group of rats served as control (vehicle only). On day 8, the animals were observed for neurobehavioral performance. Immediately after behavioral studies, the animal's brains were dissected out for histological studies. Lesions in the striatal dopaminergic neurons were assessed by immunohistochemical method using tyrosine hydroxylase immunostaining. Administration of 3-NPA alone caused significant depletion of striatal dopamine and glutathione, whereas, the levels of thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) were significantly increased suggesting an elevated level of oxidative stress. Trolox significantly and dose-dependently protected animals against 3-NPA-induced neurobehavioral, neurochemical and structural abnormalities. These results clearly suggest that protective effect of trolox against 3-NPA-induced neurotoxicity is mediated through its free radical scavenging activity.

The role of vitamin C as antioxidant in protection of oxidative stress induced by imidacloprid.

Pesticides may induce oxidative stress leading to generate free radicals and alternate antioxidant or oxygen free radical scavenging enzyme system. This study was conducted to investigate the acute toxicity of imidacloprid toward male mice and the oxidative stress of the sublethal dose (1/10 LD(50)) on the lipid peroxidation level (LPO), reduced glutathione content (GSH) and activities of the antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD), and glutathione-s-transferase (GST). Also, the protective effect of vitamin C (200mg/kg bw) 30 min before or after administration of imidacloprid were investigated. The results demonstrated that the median lethal dose (LD(50)) of imidacloprid after 24h was 149.76 mg/kg bw. The oral administration of 14.976 mg/kg imidacloprid significantly caused elevation in LPO level and the activities of antioxidant enzymes including CAT, SOD, GPx and GST. However, G6PD activity remained unchanged, while the level of GSH content was decreased. In addition, the results showed that vitamin C might ameliorate imidacloprid-induced oxidative damage by decreasing LPO and altering antioxidant defense system in liver. The protective effect of the pre-treatment with vitamin C against imidacloprid-induced oxidative stress in liver mice is better than the post-treatment.