Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The main contributory factors of Parkinson's disease (PD) are aging, genetic factors, and environmental exposure to pesticides and heavy metals. CYP2D22, a mouse ortholog of human CYP2D6, is expected to participate in a chemically induced PD phenotype due to its structural resemblance with CYP2D6. Despite its expected participation in PD, its expression in the nigrostriatal tissues and modulation by the chemicals that induce PD or offer neuroprotection have not yet been investigated. The present study was undertaken to investigate CYP2D22 expression in mouse striatum and to assess its involvement in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD phenotype and nicotine-mediated neuroprotection. The animals were treated intraperitoneally daily with nicotine (1 mg/kg) for 8 weeks, followed by MPTP (20 mg/kg) + nicotine (1 mg/kg) for 2-4 weeks and vice versa, along with respective controls. In some sets of experiments, the animals were treated with ketoconazole (300 mg/kg), a CYP3AH/CYP2D22 inhibitor, along with nicotine and/or MPTP. Tyrosine hydroxylase (TH)-immunoreactivity in the substantia nigra, the expression of nicotinic acetylcholine receptors (nAChRs) alpha6 and alpha4, dopamine content, and 1-methyl-4-phenylpyridinium ion (MPP(+)) level in the striatum were measured to confirm the MPTP-induced PD phenotype and nicotine-mediated neuroprotection. CYP2D22 and nAChRs expressions were measured in the striatum by RT-PCR/western blotting and dopamine level; CYP2D22 catalytic activity and MPP(+) content were determined by high-performance liquid chromatography (HPLC). MPTP increased dopaminergic neuronal degeneration and the striatal MPP(+) level and reduced striatal dopamine content; it attenuated expression/activity of CYP2D22 and nAChRs that were significantly restored in nicotine-treated animals. Ketoconazole reduced the nicotine-mediated increase in CYP2D22 expression and activity, dopamine content, and TH-immunoreactivity. The results indicate the expression of CYP2D22 in mouse striatum and its possible role in the MPTP-induced PD phenotype and nicotine-mediated neuroprotection.
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PMID:The expression of CYP2D22, an ortholog of human CYP2D6, in mouse striatum and its modulation in 1-methyl 4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease phenotype and nicotine-mediated neuroprotection. 1959 27

LUHMES cells are conditionally-immortalized non-transformed human fetal cells that can be differentiated to acquire a dopaminergic neuron-like phenotype under appropriate growth conditions. After differentiation by GDNF and cyclic adenosine monophosphate, LUHMES were sensitive to 1-methyl-4-phenylpyridinium (MPP(+)) toxicity at < or =5 microM, but resistant to the parental compound 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The high homogeneity and purity of the cultures allowed the detection of metabolic changes during the degeneration. Cellular ATP dropped in two phases after 24 and 48 h; cellular glutathione (GSH) decreased continuously, paralleled by an increase in lipid peroxidation. These events were accompanied by a time-dependent degeneration of neurites. Block of the dopamine transporter by GBR 12909 or mazindol completely abrogated MPP(+) toxicity. Inhibition of de novo dopamine synthesis by alpha-methyl-l-tyrosine or 3-iodo-l-tyrosine attenuated toxicity, but did not reduce the initial drop in ATP. Inhibition of mixed lineage kinases by CEP1347 completely prevented the MPP(+)-induced loss of viability and intracellular GSH, but failed to attenuate the initial drop of ATP. For the quantitative assessment of neurite degeneration, an automated imaging-based high content screening approach was applied and confirmed the findings made by pharmacological interventions in this study. Our data indicate that inhibition of mitochondrial ATP synthesis is not sufficient to trigger cell death in MPP(+)-treated LUHMES.
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PMID:Requirement of a dopaminergic neuronal phenotype for toxicity of low concentrations of 1-methyl-4-phenylpyridinium to human cells. 1964 8

Cultures of bovine adrenal medullary chromaffin cells converted 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to 1-methyl-4-phenylpyridinium (MPP(+)) by a pargyline-sensitive mechanism. Both MPTP and MPP(+) accumulated in these cells. Upon subcellular fractionation, distribution of MPP(+) paralleled that of catecholamines, suggesting storage in chromaffin vesicles. In contrast, MPTP was found in both soluble and particulate fractions, but not in chromaffin vesicles. MPTP produced a rapid depletion of 20-25% of chromaffin cell catecholamines, an action blocked by the nicotinic antagonist d-tubocurarine but not by the monoamine oxidase inhibitor pargyline. This depletion was not mimicked by MPP(+). Addition of > OR = 50 microM MPTP to chromaffin cell cultures caused additional, progressive catecholamine loss from 1 to 6 days of drug exposure that was mimicked by MPP(+) and not blocked by pargyline or d-tubocurarine. Cultures of bovine adrenal cortical cells also converted MPTP to MPP(+) and accumulated both of these drugs, but at a slower rate and to a lesser extent than chromaffin cells. Although chromaffin cells form MPP(+) from MPTP and store MPP(+), these studies suggest that catecholamine depletion in these cells results from the actions of MPTP and MPP(+) which are not stored in chromaffin vesicles. MPTP evokes catecholamine secretion from chromaffin cells via nicotinic acetylcholine receptors. MPTP and free MPP(+) are also toxic to the cells, probably through blockade of metabolic processes. These findings suggest that cells with a high capacity for MPP(+) uptake but limited vesicular storage capacity, i.e. sustained high cytoplasmic drug levels, would be susceptible to the toxic actions of this drug.
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PMID:Catecholamine depletion and accumulation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP(+)) in adrenal medullary chromaffin cells. 1965 Oct 89

Monoamine oxidase (MAO) B is a mitochondrial enzyme selectively involved in the oxidative activation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin to toxic pyridinium cations producing Parkinsonism in animal models. Various synthesized 5-nitroindazoles, 6-nitroindazole and the neuroprotectant 7-nitroindazole were examined as inhibitors of MAO and as antioxidants and radical scavengers. The oxidation of MPTP by human MAO-B and mitochondria was assessed by HPLC. Simple nitroindazoles inhibited MPTP oxidation to 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP(+)) and 1-methyl-4-phenylpyridinium (MPP(+)) in a competitive and reversible manner. 5-Nitroindazole (IC(50)=0.99 microM, K(i)=0.102 microM) and 6-nitroindazole (IC(50)=2.5 microM) were better inhibitors of human MAO-B than 7-nitroindazole (IC(50)=27.8 microM). 6-Nitroindazole also inhibited MAO-A. Nitroindazole isomers were good hydroxyl radical (OH(*)) scavengers, with 5-nitro-, 6-nitro- and 7-nitroindazole showing similar activity (k approximately 10(10) M(-1) s(-1)). Neuroprotective actions of nitroindazoles (7-nitroindazole) could be linked to their MAO-inhibitory and antiradical properties besides inhibition on nitric oxide synthase (NOS). 5-Nitro- and 6-nitroindazole, previously reported as weak NOS inhibitors, were better inhibitors of human MAO-B and more active against MPTP neurotoxin oxidation (lower MPDP(+) and MPP(+) levels) than 7-nitroindazole and acted as good radical scavengers and could be potential neuroprotective agents in addition to MAO-B inhibitors.
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PMID:Nitroindazole compounds inhibit the oxidative activation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin to neurotoxic pyridinium cations by human monoamine oxidase (MAO). 1966 97

Hypoxia-inducible factor (HIF) plays an important role in cell survival by regulating iron, antioxidant defense, and mitochondrial function. Pharmacological inhibitors of the iron-dependent enzyme class prolyl hydroxylases (PHD), which target alpha subunits of HIF proteins for degradation, have recently been demonstrated to alleviate neurodegeneration associated with stroke and hypoxic-ischemic injuries. Here we report that inhibition of PHD by 3,4-dihydroxybenzoate (DHB) protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigral dopaminergic cell loss and up-regulates HIF-1alpha within these neurons. Elevations in mRNA and protein levels of HIF-dependent genes heme oxygenase-1 (Ho-1) and manganese superoxide dismutase (Mnsod) following DHB pretreatment alone are also maintained in the presence of MPTP. MPTP-induced reductions in ferroportin and elevations in nigral and striatal iron levels were reverted to levels comparable with that of untreated controls with DHB pretreatment. Reductions in pyruvate dehydrogenase mRNA and activity resulting from MPTP were also found to be attenuated by DHB. In vitro, the HIF pathway was activated in N27 cells grown at 3% oxygen treated with either PHD inhibitors or an iron chelator. Concordant with our in vivo data, the MPP(+)-elicited increase in total iron as well as decreases in cell viability were attenuated in the presence of DHB. Taken together, these data suggest that protection against MPTP neurotoxicity may be mediated by alterations in iron homeostasis and defense against oxidative stress and mitochondrial dysfunction brought about by cellular HIF-1alpha induction. This study provides novel data extending the possible therapeutic utility of HIF induction to a Parkinson disease model of neurodegeneration, which may prove beneficial not only in this disorder itself but also in other diseases associated with metal-induced oxidative stress.
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PMID:Inhibition of prolyl hydroxylase protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity: model for the potential involvement of the hypoxia-inducible factor pathway in Parkinson disease. 1967 56

Parkinson's disease (PD) is second only to Alzheimer's disease as the most common devastating human neurodegenerative disorder. Despite intense investigation, no interdictive therapy is available for PD. We investigated whether simvastatin, a Food and Drug Administration-approved cholesterol-lowering drug, could protect against nigrostriatal degeneration after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication to model PD in mice. First, MPP(+) induced the activation of p21(ras) and nuclear factor-kappaB (NF-kappaB) in mouse microglial cells. Inhibition of MPP(+)-induced activation of NF-kappaB by Deltap21(ras), a dominant-negative mutant of p21(ras), supported the involvement of p21(ras) in MPP(+)-induced microglial activation of NF-kappaB. Interestingly, simvastatin attenuated activation of both p21(ras) and NF-kappaB in MPP(+)-stimulated microglial cells. Consistently, we found a very rapid activation of p21(ras) in vivo in the substantia nigra pars compacta of MPTP-intoxicated mice. However, after oral administration, simvastatin entered into the nigra, reduced nigral activation of p21(ras), attenuated nigral activation of NF-kappaB, inhibited nigral expression of proinflammatory molecules, and suppressed nigral activation of glial cells. These findings paralleled dopaminergic neuronal protection, normalized striatal neurotransmitters, and improved motor functions in MPTP-intoxicated mice. Similarly, pravastatin, another cholesterol-lowering drug, suppressed microglial inflammatory responses and protected dopaminergic neurons in MPTP-intoxicated mice, but at levels less than simvastatin. Furthermore, both the statins administered 2 d after initiation of the disease were still capable of inhibiting the demise of dopaminergic neurons and concomitant loss of neurotransmitters, suggesting that statins are capable of slowing down the progression of neuronal loss in the MPTP mouse model. Therefore, we conclude that statins may be of therapeutic benefit for PD patients.
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PMID:Simvastatin inhibits the activation of p21ras and prevents the loss of dopaminergic neurons in a mouse model of Parkinson's disease. 1986 67

Neural injury leads to inflammation and activation of microglia that in turn may participate in progression of neurodegeneration. The mechanisms involved in changing microglial activity from beneficial to chronic detrimental neuroinflammation are not known but reactive oxygen species (ROS) may be involved. We have addressed this question in Nrf2-knockout mice, with hypersensitivity to oxidative stress, submitted to daily inoculation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 4 weeks. Basal ganglia of these mice exhibited a more severe dopaminergic dysfunction than wild type littermates in response to MPTP. The amount of CD11b-positive/CD45-highly-stained cells, indicative of peripheral macrophage infiltration, did not increase significantly in response to MPTP. However, Nrf2-deficient mice exhibited more astrogliosis and microgliosis as determined by an increase in messenger RNA and protein levels for GFAP and F4/80, respectively. Inflammation markers characteristic of classical microglial activation, COX-2, iNOS, IL-6, and TNF-alpha were also increased and, at the same time, anti-inflammatory markers attributable to alternative microglial activation, such as FIZZ-1, YM-1, Arginase-1, and IL-4 were decreased. These results were confirmed in microglial cultures stimulated with apoptotic conditioned medium from MPP(+)-treated dopaminergic cells, further demonstrating a role of Nrf2 in tuning balance between classical and alternative microglial activation. This study demonstrates a crucial role of Nrf2 in modulation of microglial dynamics and identifies Nrf2 as molecular target to control microglial function in Parkinson's disease (PD) progression.
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PMID:Nrf2 regulates microglial dynamics and neuroinflammation in experimental Parkinson's disease. 1990 87

We tested the hypothesis that long-term l-DOPA treatment in Parkinson's disease (PD) would result in increased production of the dopamine oxidation product, 6-hydroxydopamine (6-OHDA) in the striatum. We administered L-DOPA (250 mg/kg) by gavation for 3 days following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg, i.p., twice, 16 h apart) in mice or for 30 days in rats which received 1-methyl-4-phenylpyridinium ion (MPP(+); 16 nmol/1 microl) unilaterally in median forebrain bundle, and measured 6-OHDA in the striatum using a sensitive HPLC-electrochemical detection procedure. While the contralateral innervated striatum of rats showed no difference, a significant increase in 6-OHDA level in the denervated (>85% dopamine depletion) ipsilateral striatum was observed. Partial nigrostriatal denervation with a lower dose of MPP(+) (8 nmol/1 microl) in rats or following sub-acute MPTP treatment in mice failed to cause any significant change in 6-OHDA level following several doses of L-DOPA administration. Since a single dose of MPTP (30 mg/kg, i.p.) or L-deprenyl (0.25 mg/kg, i.p.) in L-DOPA primed (250 mg/kg daily for 7 days) mice caused significant increase in 6-OHDA in the striatum, augmentation of reactive oxygen species production concomitant to excessive dopamine concentration in this region is proposed to be the basis of this effect. These results suggest creation of potential pro-toxic environment in the brain due to the long-term administration of L-DOPA, which may get further sensitized by the treatment of monoamine oxidase inhibitors.
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PMID:L-DOPA-induced 6-hydroxydopamine production in the striata of rodents is sensitive to the degree of denervation. 1993 35

In the present work we report the generation of a new line of alpha-synuclein (alpha-SYN) transgenic mice in which the human wild-type alpha-SYN cDNA is expressed under the control of a tyrosine hydroxylase (TH) promoter. We provide evidence that the ectopic protein is found in TH expressing neurons of both central and peripheral nervous systems. The transgene is expressed very early in development coinciding with the activity of the TH promoter and in the adult brain the human protein distributes normally to the nerve endings and cell bodies of dopaminergic nigral neurons without any evidence of abnormal aggregation. Our results indicate that expression of human wild-type alpha-SYN does not affect normal development or maintenance of TH immunoreactive nigral neurons, striatal dopamine content, or locomotor activity. Systemic administration of the parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces a loss of TH immunoreactive nigral neurons and terminals and of dopamine levels to the same degree in both transgenic and non-transgenic adult mice. Intoxication also results in a similar loss of cardiac noradrenaline in both genotypes. Surprisingly, cultured transgenic ventral mesencephalic fetal dopaminergic neurons exhibit complete resistance to cell death induced by 1-methyl-4-phenylpyridinium ion (MPP(+)) intoxication, without changes in dopamine transporter (DAT) surface levels. Interestingly, this protection is not observed in other populations of catecholaminergic neurons such as peripheral sympathetic neurons, despite their high sensitivity to MPP(+)in vitro.
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PMID:Prosurvival effect of human wild-type alpha-synuclein on MPTP-induced toxicity to central but not peripheral catecholaminergic neurons isolated from transgenic mice. 2015 26

The present study examined the inhibitory effect of licorice compounds glycyrrhizin and a metabolite 18beta-glycyrrhetinic acid on the neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the mouse and on the 1-methyl-4-phenylpyridinium (MPP(+))-induced cell death in differentiated PC12 cells. MPTP treatment increased the activities of total superoxide dismutase, catalase and glutathione peroxidase and the levels of malondialdehyde and carbonyls in the brain compared to control mouse brain. Co-administration of glycyrrhizin (16.8 mg/kg) attenuated the MPTP effect on the enzyme activities and formation of tissue peroxidation products. In vitro assay, licorice compounds attenuated the MPP(+)-induced cell death and caspase-3 activation in PC12 cells. Glycyrrhizin up to 100microM significantly attenuated the toxicity of MPP(+). Meanwhile, 18beta-glycyrrhetinic acid showed a maximum inhibitory effect at 10microM; beyond this concentration the inhibitory effect declined. Glycyrrhizin and 18beta-glycyrrhetinic acid attenuated the hydrogen peroxide- or nitrogen species-induced cell death. Results from this study indicate that glycyrrhizin may attenuate brain tissue damage in mice treated with MPTP through inhibitory effect on oxidative tissue damage. Glycyrrhizin and 18beta-glycyrrhetinic acid may reduce the MPP(+) toxicity in PC12 cells by suppressing caspase-3 activation. The effect seems to be ascribed to the antioxidant effect.
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PMID:Glycyrrhizin Attenuates MPTP Neurotoxicity in Mouse and MPP-Induced Cell Death in PC12 Cells. 2015 96


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