Genetic vitamin E deficiency does not affect MPTP susceptibility in the mouse brain

Oxidative stress is involved in the degeneration of the nigrostriatal dopaminergic system in Parkinson's disease (PD). Vitamin E (alpha-tocopherol) is a potent antioxidant in the cell membrane that can trap free radicals and prohibit lipid peroxidation. The retention and secretion of vitamin E are regulated by alpha-tocopherol transfer protein (TTP) in the brain and liver. Dysfunction of TTP results in systemic deficiency of vitamin E in humans and mice, and increased oxidative stress in mouse brain. In this study, we investigated the effect of vitamin E deficiency in PD development by generating an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD using TTP knockout (TTP-/-) mice. Vitamin E concentration in the brains of TTP+/- mice was half that in TTP+/+ mice, and in TTP-/- mice, was undetectable. MPTP treatment tended to decrease striatal dopamine, but the effect was comparable and not significant in any of the three genotypes. Furthermore, the extent of loss of dopaminergic cell bodies in the substantia nigra did not differ among the groups. One the other hand, oral administration of vitamin E resulted in the partial protection of striatal dopaminergic terminals against MPTP toxicity. Our results suggest that vitamin E does not play a major protective role in MPTP-induced nigrostriatal dopaminergic neurodegeneration in the brain.     

Mangiferin attenuates MPTP induced dopaminergic neurodegeneration and improves motor impairment,redox balance and Bcl-2/Bax expression in experimental Parkinson’s disease mice

Mangiferin, a polyphenol compound of C-glucoside, is well-known for its anti-inflammatory, antioxidant, anticancer, antidiabetic and cognitive enhancement properties. In this study, we investigated the neuroprotective effect of mangiferin against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease (PD), which is most popular and widely used to evaluate therapeutic implications of new protective agents. Male C57BL/6 mice were orally treated with mangiferin (10, 20 and 40 mg/kg body wt.) for 14 days and from 10th day onwards MPTP (30 mg/kg, i.p.) was injected for last 5 days. MPTP treatment leads to enhanced oxidative stress, induction of apoptosis (upregulates the expression of Bax, proapoptotic protein and downregulates the expression of anti-apoptotic marker Bcl-2), and loss of dopominergic neurons which results in motor impairments. Results of our study confirmed that mangiferin prevented MPTP-induced behavioral deficits, oxidative stress, apoptosis, dopaminergic neuronal degeneration and dopamine depletion. Taken together, we conclude that mangiferin attenuates the dopaminergic neurodegeneration mainly through its potent antioxidant and antiapoptotic properties.     

Tauroursodeoxycholic Acid Prevents MPTP-Induced Dopaminergic Cell Death in a Mouse Model of Parkinson’s Disease

Mitochondrial dysfunction and oxidative stress are implicated in the neurodegenerative process in Parkinson??s disease (PD). Moreover, c-Jun N-terminal kinase (JNK) plays an important role in dopaminergic neuronal death in substantia nigra pars compacta. Tauroursodeoxycholic acid (TUDCA) acts as a mitochondrial stabilizer and anti-apoptotic agent in several models of neurodegenerative diseases. Here, we investigated the role of TUDCA in preventing 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurodegeneration in a mouse model of PD. We evaluated whether TUDCA modulates MPTP-induced degeneration of dopaminergic neurons in the nigrostriatal axis, and if that can be explained by regulation of JNK phosphorylation, reactive oxygen species (ROS) production, glutathione S-transferase (GST) catalytic activation, and Akt signaling, using C57BL/6 glutathione S-transferase pi (GSTP) null mice. TUDCA efficiently protected against MPTP-induced dopaminergic degeneration. We have previously demonstrated that exacerbated JNK activation in GSTP null mice resulted in increased susceptibility to MPTP neurotoxicity. Interestingly, pre-treatment with TUDCA prevented MPTP-induced JNK phosphorylation in mouse midbrain and striatum. Moreover, the anti-oxidative role of TUDCA was demonstrated in vivo by impairment of ROS production in the presence of MPTP. Finally, results herein suggest that the survival pathway activated by TUDCA involves Akt signaling, including downstream Bad phosphorylation and NF-??B activation. We conclude that TUDCA is neuroprotective in an in vivo model of PD, acting mainly by modulation of JNK activity and cellular redox thresholds, together with activation of the Akt pro-survival pathway. These results open new perspectives for the pharmacological use of TUDCA, as a modulator of neurodegeneration in PD.     

Gastrodin prevents motor deficits and oxidative stress in the MPTP mouse model of Parkinson's disease: Involvement of ERK1/2–Nrf2 signaling pathway

Aims

Current no effective therapy is available to halt the progression of Parkinson's disease (PD). Oxidative stress has been implicated in the etiology of PD. The present study evaluates the hypothesis that prevention of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits by gastrodin might mainly result from its antioxidant property via interrupting extracellular signal regulated protein kinases (ERK) 1/2-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway.

Main methods

Pretreatment of mouse model of PD is established by treating C57BL/6 mice with 4 doses of MPTP (30 mg/kg per day, i.p.), with gastrodin (60 mg/kg per day) administered by daily intraperitoneal injection for 2 weeks. Motor behavior of mice was monitored by open-field test and rotarod test. Real-time polymerase chain reaction and Western blotting were used to analyze the expression of genes.

Key findings

MPTP-induced motor deficits were partially and significantly forestalled by gastrodin. Gastrodin treatment prevented MPTP-induced oxidative stress, as measured by malondialdehyde in midbrain. Interestingly, MPTP-intoxicated mice treated with gastrodin robustly increased heme oxygenase 1, superoxide dismutase, glutathione levels, and Nrf2 nuclear translocation in striatum of MPTP-intoxicated mice. Furthermore, results herein suggest that the antioxidant pathway activated by gastrodin involves ERK1/2 phosphorylation.

Significance

Gastrodin protects midbrain of MPTP-intoxicated mice against oxidative stress, in part, through interrupting ERK1/2–Nrf2 pathway mechanism, which will give us an insight into the potential of gastrodin in terms of opening up new therapeutic avenues for PD.     

Apoptosis signal-regulating kinase 1 mediates MPTP toxicity and regulates glial activation

Apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein kinase 3 family, is activated by oxidative stress. The death-signaling pathway mediated by ASK1 is inhibited by DJ-1, which is linked to recessively inherited Parkinson''s disease (PD). Considering that DJ-1 deficiency exacerbates the toxicity of the mitochondrial complex I inhibitor 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we sought to investigate the direct role and mechanism of ASK1 in MPTP-induced dopamine neuron toxicity. In the present study, we found that MPTP administration to wild-type mice activates ASK1 in the midbrain. In ASK1 null mice, MPTP-induced motor impairment was less profound, and striatal dopamine content and nigral dopamine neuron counts were relatively preserved compared to wild-type littermates. Further, microglia and astrocyte activation seen in wild-type mice challenged with MPTP was markedly attenuated in ASK1^−/− mice. These data suggest that ASK1 is a key player in MPTP-induced glial activation linking oxidative stress with neuroinflammation, two well recognized pathogenetic factors in PD. These findings demonstrate that ASK1 is an important effector of MPTP-induced toxicity and suggest that inhibiting this kinase is a plausible therapeutic strategy for protecting dopamine neurons in PD.     

Soluble Epoxide Hydrolase Inhibition Attenuates MPTP-Induced Neurotoxicity in the Nigrostriatal Dopaminergic System: Involvement of α-Synuclein Aggregation and ER Stress

Soluble epoxide hydrolase (sEH) is widely expressed in the mammalian brain and possesses dual enzymatic activities, including C-terminal epoxide hydrolase (C-EH) which degrades epoxyeicosatrienoic acid (EET), a beneficial arachidonic acid metabolite. In the present study, the neuroprotective effect of sEH inhibition on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurodegeneration of nigrostriatal dopaminergic system was investigated using genetic and pharmacological approaches. MPTP (15 mg/kg) was intraperitoneally injected in sEH knockout (KO) mice and C57BL/6J mice as wild-type (WT) mice. Compared with the MPTP-treated WT mice, MPTP-induced reductions in striatal dopamine content and nigral tyrosine hydroxylase level (TH, a biomarker of dopaminergic neurons) were less significant in the treated sEH mice. Furthermore, MPTP-induced HO-1 elevation (a redox-regulated protein), α-synuclein aggregation, and caspase 12 activation (a hallmark of ER stress) were less prominent in sEH KO mice than in WT mice. These data indicate that sEH KO mice are more resistant to MPTP-induced neurotoxicity. The pharmacological effect of N-[1-(1-oxopropyl)-4-piperidinyl]-N0-[4-(trifluoromethoxy)phenyl)-urea (TPPU, an sEH inhibitor) on MPTP-induced neurotoxicity was investigated in WT mice. TPPU (1 mg/kg, i.p.) attenuated MPTP-induced reduction in striatal dopamine content, TH-positive cell numbers, TH, and pro-caspase 9 protein levels (an initiator caspase of apoptosis) in mouse SN. Moreover, TPPU reduced MPTP-induced HO-1 elevation, α-synuclein aggregation and caspase 12 activation, indicating that TPPU is effective in attenuating MPTP-induced oxidative stress, apoptosis, protein aggregation, and ER stress. In conclusion, our study suggests that sEH is a potential target for developing therapies for parkinsonism. Furthermore, sEH inhibitors may be of clinical significance for treating CNS neurodegenerative diseases.     

The influence and the mechanism of docosahexaenoic acid on a mouse model of Parkinson's disease

This study aimed to investigate the effects of docosahexaenoic acid (DHA) on the oxidative stress that occurs in an experimental mouse model of Parkinson’s disease (PD). An experimental model of PD was created by four intraperitoneal injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (4 × 20 mg/kg, at 12 h intervals). Docosahexaenoic acid was given daily by gavage for 4 weeks (36 mg/kg/day). The motor activity of the mice was evaluated via the pole test, and the dopaminergic lesion was determined by immunohistochemical analysis for tyrosine hydroxylase (TH)-immunopositive cells. The activity of antioxidant enzymes in the brain were determined by spectrophotometric assays and the concentration of thiobarbituric acid-reactive substances (TBARS) were measured as an index of oxidative damage. The number of apoptotic dopaminergic cells significantly increased in MPTP-treated mice compared to controls. Although DHA significantly diminished the number of cell deaths in MPTP-treated mice, it did not improve the decreased motor activity observed in the experimental PD model. Docosahexaenoic acid significantly diminished the amount of cell death in the MPTP + DHA group as compared to the MPTP group. TBARS levels in the brain were significantly increased following MPTP treatment. Glutathione peroxidase (GPx) and catalase (CAT) activities of brain were unaltered in all groups. The activity of brain superoxide dismutase (SOD) was decreased in the MPTP-treated group compared to the control group, but DHA treatment did not have an effect on SOD activity in the MPTP + DHA group. Our current data show that DHA treatment exerts neuroprotective actions on an experimental mouse model of PD. There was a decrease tendency in brain lipid oxidation of MPTP mice but it did not significantly.     

Gene-environment Interaction Models to Unmask Susceptibility Mechanisms in Parkinson's Disease

Lipoxygenase (LOX) activity has been implicated in neurodegenerative disorders such as Alzheimer''s disease, but its effects in Parkinson''s disease (PD) pathogenesis are less understood. Gene-environment interaction models have utility in unmasking the impact of specific cellular pathways in toxicity that may not be observed using a solely genetic or toxicant disease model alone. To evaluate if distinct LOX isozymes selectively contribute to PD-related neurodegeneration, transgenic (i.e. 5-LOX and 12/15-LOX deficient) mice can be challenged with a toxin that mimics cell injury and death in the disorder. Here we describe the use of a neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces a nigrostriatal lesion to elucidate the distinct contributions of LOX isozymes to neurodegeneration related to PD. The use of MPTP in mouse, and nonhuman primate, is well-established to recapitulate the nigrostriatal damage in PD. The extent of MPTP-induced lesioning is measured by HPLC analysis of dopamine and its metabolites and semi-quantitative Western blot analysis of striatum for tyrosine hydroxylase (TH), the rate-limiting enzyme for the synthesis of dopamine. To assess inflammatory markers, which may demonstrate LOX isozyme-selective sensitivity, glial fibrillary acidic protein (GFAP) and Iba-1 immunohistochemistry are performed on brain sections containing substantia nigra, and GFAP Western blot analysis is performed on striatal homogenates. This experimental approach can provide novel insights into gene-environment interactions underlying nigrostriatal degeneration and PD.     

Reduced calcium/calmodulin-dependent protein kinase II activity in the hippocampus is associated with impaired cognitive function in MPTP-treated mice

Parkinson's disease (PD) patients frequently reveal deficit in cognitive functions during the early stage in PD. The dopaminergic neurotoxin, MPTP-induced neurodegeneration causes an injury of the basal ganglia and is associated with PD-like behaviors. In this study, we demonstrated that deficits in cognitive functions in MPTP-treated mice were associated with reduced calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation and impaired long-term potentiation (LTP) induction in the hippocampal CA1 region. Mice were injected once a day for 5days with MPTP (25mg/kg i.p.). The impaired motor coordination was observed 1 or 2week after MPTP treatment as assessed by rota-rod and beam-walking tasks. In immunoblotting analyses, the levels of tyrosine hydroxylase protein and CaMKII autophosphorylation in the striatum were significantly decreased 1week after MPTP treatment. By contrast, deficits of cognitive functions were observed 3-4weeks after MPTP treatment as assessed by novel object recognition and passive avoidance tasks but not Y-maze task. Impaired LTP in the hippocampal CA1 region was also observed in MPTP-treated mice. Concomitant with impaired LTP induction, CaMKII autophosphorylation was significantly decreased 3weeks after MPTP treatment in the hippocampal CA1 region. Finally, the reduced CaMKII autophosphorylation was closely associated with reduced AMPA-type glutamate receptor subunit 1 (GluR1; Ser-831) phosphorylation in the hippocampal CA1 region of MPTP-treated mice. Taken together, decreased CaMKII activity with concomitant impaired LTP induction in the hippocampus likely account for the learning disability observed in MPTP-treated mice.     

Recombinant human granulocyte colony-stimulating factor protects against MPTP-induced dopaminergic cell death in mice by altering Bcl-2/Bax expression levels

Granulocyte colony-stimulating factor (G-CSF) has been used for the treatment of neutropenia in hematologic disorders. The neuroprotective effects of G-CSF were reported in neurological disease models. In the present study, we examined whether G-CSF can protect dopaminergic neurons against MPTP-induced cell death in a mouse model of Parkinson's disease. Mice of one group were injected intraperitoneally with MPTP for five consecutive days, those of another group with MPTP and intraperitoneal G-CSF at 2 days and 1 day before the first MPTP injection, and 30 min before each MPTP injection, while control mice received saline injections. Immunohistochemistry, western blotting analysis, and HPLC were performed to evaluate damage of substantia nigra dopaminergic neurons and expression of Bcl-2 and Bax protein. MPTP induced dopaminergic cell death in the substantia nigra. G-CSF significantly prevented MPTP-induced loss of tyrosine hydroxylase-positive neurons (p < 0.05), increased Bcl-2 protein and decreased Bax protein expression. Our findings indicate that G-CSF provides neuroprotection against MPTP-induced cell death and this effect is mediated by increasing Bcl-2 expression levels and decreasing Bax expression levels in C57BL/6 mice.     

Attenuation of MPTP-induced neurotoxicity and locomotor dysfunction in Nucling-deficient mice via suppression of the apoptosome pathway

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity is one of the experimental models most commonly used to study the pathogenesis of Parkinson's disease (PD). Although the biochemical mechanisms underlying the cell death induced by MPTP remain to be clarified, it has been found that the mitochondrial apoptotic signaling pathway plays an important role in the neurotoxicity of MPTP. Nucling is a novel type of apoptosis-associated molecule, essential for cytochrome c, apoptosis protease activating factor 1 (Apaf-1), pro-caspase-9 apoptosome induction and caspase-9 activation following pro-apoptotic stress. Here we found that Nucling-deficient mice treated with MPTP did not exhibit locomotor dysfunction in an open-field test. The substantia nigra dopaminergic neurons of Nucling-deficient mice were resistant to the damaging effects of the neurotoxin MPTP. Up-regulated expression of apoptosome was attenuated in Nucling-deficient mice treated with MPTP. These results indicate an important role for Nucling in MPTP-induced neuronal degeneration and suggest that the suppression of Nucling would be of therapeutic benefit for the treatment of neurodegeneration in PD.     

Platelet-activating factor receptor knockout mice are protected from MPTP-induced dopaminergic degeneration

Platelet-activating factor (PAF), a potent mediator of inflammatory and immune responses, plays various roles in neuronal functions. However, little is known about the role of PAF/platelet-activating factor receptor (PAF-R) in Parkinson’s disease. Treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) resulted in significant increases in PAF species in the striatum of wild-type mice. These increases paralleled PAF-R gene expression in wild-type mice. Although nuclear factor kappa B (NF-κB) DNA-binding activity was increased significantly in MPTP-treated wild-type mice, this increase was not significant in PAF-R antagonist ginkgolide B (GB)-treated mice or PAF-R knockout (PAF-R^−/−) mice. Pyrrolidine dithiocarbamate (PDTC), an NF-κB inhibitor, significantly ameliorated the dopaminergic deficits induced by MPTP in wild-type mice. MPTP treatment significantly increased oxidative damage, the immunoreactivity of ionized calcium binding adaptor molecule 1 (Iba-1)-positive microglial cells, and microglial differentiation of the M1 type in the striatum of wild-type mice. Consistently, PDTC significantly attenuated MPTP-induced behavioral impairments in wild-type mice. However, dopaminergic deficits, oxidative damage, reactive microglial cells, and behavioral impairments induced by MPTP were not significantly observed in GB-treated mice or PAF-R^−/− mice. PDTC did not significantly alter the attenuations evident in MPTP-treated PAF-R^−/− mice, indicating that NF-κB is a critical target for neurotoxic modulation of PAF-R. We propose for the first time that PAF/PAF-R can mediate dopaminergic degeneration via an NF-κB-dependent signaling process.     

Proteomic analysis of the neuroprotective mechanisms of acupuncture treatment in a Parkinson's disease mouse model

Acupuncture is frequently used as an alternative therapy for Parkinson's disease (PD), and it attenuates dopaminergic (DA) neurodegeneration in the substantia nigra (SN) in PD animal models. Using proteomic analysis, we investigated whether acupuncture alters protein expression in the SN to favor attenuation of neuronal degeneration. In C57BL/6 mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg/day), intraperitoneal (i.p.) for 5 days, 2 or 100 Hz electroacupuncture (EA) was applied at the effective and specific acupoint, GB34, once a day for 12 consecutive days from the first MPTP treatment. Both treatments in MPTP mice led to restoration of behavioral impairment and rescued tyrosine hydroxylase (TH)-positive DA neurodegeneration. Using peptide fingerprinting MS, we identified changes in 22 proteins in the SN following MPTP treatment, and nine of these proteins were normalized by EA. They were involved in cell death regulation, inflammation, or restoration from damage. The levels of cyclophilin A (CypA), which is a neuroprotective agent, were unchanged by MPTP treatment but were increased in MPTP-EA mice. These results suggest that acupoint GB34-specific EA changes protein expression profiles in the SN in favor of DA neuronal survival in MPTP-treated mice, and that EA treatment may be an effective therapy for PD patients.     

Oxidative stress-induced expression of HSP70 contributes to the inhibitory effect of 15d-PGJ2 on inducible prostaglandin pathway in chondrocytes

The inhibitory effect of 15-deoxy-Δ^12,14-prostaglandin J₂ (15d-PGJ₂) on proinflammatory gene expression has been extensively documented and frequently ascribed to its ability to prevent NF-κB pathway activation. We and others have previously demonstrated that it was frequently independent of the peroxisome proliferator activated receptor (PPAR)γ activation. Here, we provide evidence that induction of intracellular heat shock protein (HSP)70 by oxidative stress is an additional regulatory loop supporting the anti-inflammatory effect of 15d-PGJ₂ in chondrocytes. Using real-time quantitative PCR and Western blotting, we showed that 15d-PGJ₂ stimulated HSP70, but not HSP27 expression while increasing oxidative stress as measured by spectrofluorimetry and confocal spectral imaging. Using N-acetylcysteine (NAC) as an antioxidant, we demonstrated further that oxidative stress was thoroughly responsible for the increased expression of HSP70. Finally, using an HSP70 antisense strategy, we showed that the inhibitory effect of 15d-PGJ₂ on IL-1-induced activation of the NF-κB pathway, COX-2 and mPGES-1 expression, and PGE₂ synthesis was partly supported by HSP70. These data provide a new anti-inflammatory mechanism to support the PPARγ-independent effect of 15d-PGJ₂ in chondrocyte and suggest a possible feedback regulatory loop between oxidative stress and inflammation via intracellular HSP70 up-regulation. This cross talk is consistent with 15d-PGJ₂ as a putative negative regulator of the inflammatory reaction.     

Inflammation induces mitochondrial dysfunction and dopaminergic neurodegeneration in the nigrostriatal system

Evidence suggests that chronic inflammation, mitochondrial dysfunction, and oxidative stress play significant and perhaps synergistic roles in Parkinson's disease (PD), where the primary pathology is significant loss of the dopaminergic neurons in the substantia nigra. The use of anti-inflammatory drugs for PD treatment has been proposed, and inhibition of cyclo-oxygenase-2 (COX-2) or activation of peroxisome proliferator-activated receptor gamma (PPAR-gamma) yields neuroprotection in MPTP-induced PD. Lipopolysaccharide (LPS) induces inflammation-driven dopaminergic neurodegeneration. We tested the hypothesis that celecoxib (Celebrex, COX-2 inhibitor) or pioglitazone (Actos, PPAR-gamma agonist) will reduce the LPS-induced inflammatory response, spare mitochondrial bioenergetics, and improve nigral dopaminergic neuronal survival. Rats were treated with vehicle, celecoxib, or pioglitazone and were intrastriatally injected with LPS. Inflammation, mitochondrial dysfunction, oxidative stress, decreased dopamine, and nigral dopaminergic neuronal loss were observed post-LPS. Celecoxib and pioglitazone provided neuroprotective properties by decreasing inflammation and restoring mitochondrial function. Pioglitazone also attenuated oxidative stress and partially restored striatal dopamine as well as demonstrated dopaminergic neuroprotection and reduced nigral microglial activation. In summary, intrastriatal LPS served as a model for inflammation-induced dopaminergic neurodegeneration, anti-inflammatory drugs provided protective properties, and pioglitazone or celecoxib may have therapeutic potential for the treatment of neuro-inflammation and PD.     

2-Deoxyglucose Enhances 1-Methyl-4-Phenyl-1, 2, 3, 6-Tetrahydropyridine-Induced ATP Loss in the Mouse Brain

Abstract: The effects of 2-deoxyglucose (2-DG), an inhibitor of the uptake and use of glucose, on ATP loss caused by the neurotoxicant 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) were determined in the mouse brain. 2-DG alone had no effect on brain ATP levels, but when administered 30 min before MPTP exposure, 2-DG significantly enhanced MPTP-induced ATP reduction. This was reflected as an increase in ATP loss in the striatum (from 15 to 27%) as well as a significant decrease in ATP in the cerebellar cortex, an area of the brain that was not affected after exposure to MPTP alone. In mice pretreated with 2-DG, striatal ATP levels remained significantly decreased for >8 h after MPTP administration. In contrast, ATP levels in the cerebellar cortex returned to normal values within 4 h from MPTP exposure. Mazindol, a catecholamine uptake blocker, completely protected against MPTP-induced loss of striatal ATP in the absence of 2-DG, but it only partially prevented striatal ATP decrease after administration of both 2-DG and MPTP; mazindol was also ineffective in protecting against ATP loss caused by 2-DG and MPTP in the cerebellar cortex. 2-DG/MPTP-induced ATP loss appeared to be associated with the presence of the 1 -methyl-4-phenylpyridinium (MPP⁺) metabolite because (1) the pattern of ATP recovery in the striatum and cerebellar cortex appeared to reflect the pattern of MPP⁺clearance from these areas of the brain (i.e., significant MPP⁺ levels persisted longer in the striatum than in the cerebellar cortex), and (2) ATP decrease was completely prevented by blocking the conversion of MPTP to MPP⁺with the monoamine oxidase B inhibitor deprenyl. Data indicate that impairment of glucose metabolism dramatically enhances the effects of MPTP/MPP⁺ on cerebral energy supplies, making these effects relatively nonselective for dopaminergic neurons of the nigrostriatal pathway.     

Hydrogen in Drinking Water Reduces Dopaminergic Neuronal Loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine Mouse Model of Parkinson's Disease

It has been shown that molecular hydrogen (H₂) acts as a therapeutic antioxidant and suppresses brain injury by buffering the effects of oxidative stress. Chronic oxidative stress causes neurodegenerative diseases such as Parkinson''s disease (PD). Here, we show that drinking H₂-containing water significantly reduced the loss of dopaminergic neurons in PD model mice using both acute and chronic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The concentration-dependency of H₂ showed that H₂ as low as 0.08 ppm had almost the same effect as saturated H₂ water (1.5 ppm). MPTP-induced accumulation of cellular 8-oxoguanine (8-oxoG), a marker of DNA damage, and 4-hydroxynonenal (4-HNE), a marker of lipid peroxidation were significantly decreased in the nigro-striatal dopaminergic pathway in mice drinking H₂-containing water, whereas production of superoxide (O₂•⁻) detected by intravascular injection of dihydroethidium (DHE) was not reduced significantly. Our results indicated that low concentration of H₂ in drinking water can reduce oxidative stress in the brain. Thus, drinking H₂-containing water may be useful in daily life to prevent or minimize the risk of life style-related oxidative stress and neurodegeneration.     

PEP-1-HO-1 prevents MPTP-induced degeneration of dopaminergic neurons in a Parkinson’s disease mouse model

Heme oxygenase-1 (HO-1) degrades heme to carbon dioxide, biliverdin, and Fe²⁺, which play important roles in various biochemical processes. In this study, we examined the protective function of HO-1 against oxidative stress in SH-SY5Y cells and in a Parkinson’s disease mouse model. Western blot and fluorescence microscopy analysis demonstrated that PEP-1-HO-1, fused with a PEP-1 peptide can cross the cellular membranes of human neuroblastoma SH-SY5Y cells. In addition, the transduced PEP-1-HO-1 inhibited generation of reactive oxygen species (ROS) and cell death caused by 1-methyl-4-phenylpyridinium ion (MPP⁺). In contrast, HO-1, which has no ability to transduce into SH-SY5Y cells, failed to reduce MPP⁺-induced cellular toxicity and ROS production. Furthermore, intraperitoneal injected PEP-1-HO-1 crossed the blood-brain barrier in mouse brains. In a PD mouse model, PEP-1-HO-1 significantly protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity and dopaminergic neuronal death. Therefore, PEP-1-HO-1 could be a useful agent in treating oxidative stress induced ailments including PD. [BMB Reports 2014; 47(10): 569-574]