Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The discovery of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity stimulated intense interest in neurotoxicology and in the possible toxic etiology of Parkinson's disease. Better understanding of MPTP neurotoxicity may be achieved by studies using 18F-radiolabeled MPTP analogs and positron emission tomography in nonhuman primates. We synthesized three fluorinated analogs of MPTP: 1-methyl-4-(2-fluorophenyl)-1,2,3,6-tetrahydropyridine (2'-F-MPTP), 1-methyl-4-[2-(trifluoromethyl)phenyl]-1,2,3,6-tetrahydropyridine (2'-CF3-MPTP) and 1-methyl-4-[2-(fluoromethyl)phenyl]-1,2,3,6-tetrahydropyridine (2'-CH2F-MPTP), and developed a method for preparing the latter in 18F-labeled form. We now studied the suitability of 2'-CH2F-MPTP and its hydrolysis products as substrates for monoamine oxidase (MAO) from mouse and monkey brain preparations, and investigated the neurotoxic effect of 2'-CH2F-MPTP and 2'-F-MPTP on the nigrostriatal dopaminergic system in mice. We found that 2'-CH2F-MPTP is a better substrate for MAO and that both 2'-CH2F-MPTP and 2'-F-MPTP were more potent neurotoxins than MPTP. Like MPTP, 2'-F-MPTP was exclusively oxidized by MAO-B and its toxicity blocked by pargyline or deprenyl but not by clorgyline. In contrast, 2'-CH2F-MPTP was oxidized by both MAO-A and MAO-B, and its toxicity was not blocked by pargyline, clorgyline or deprenyl when given separately, but required clorgyline and deprenyl together.
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PMID:Development of fluorinated 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine analogs with potent nigrostriatal toxicity for potential use in positron emission tomography studies. 835 8

To examine the effects of nigrostriatal denervation on the substantia nigra pars reticulata (SNpr), one of the main outputs of the basal ganglia, we used quantitative in situ hybridization to analyze the messenger RNA coding for Mr 67,000 glutamic acid decarboxylase (GAD67 mRNA) in the SNpr neurons from patients with Parkinson's disease (PD), monkeys rendered parkinsonian by 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine (MPTP), and their respective controls. In MPTP-intoxicated monkeys, the expression of GAD67 mRNA was increased in the SNpr neurons, and the increase was reversed by L-dopa treatment. There were no differences in the level of GAD67 mRNA between PD patients who had been treated with L-dopa and control subjects. Combined with the previously reported increased expression of GAD67 mRNA in the internal segment of the pallidum of MPTP-intoxicated monkeys, these data suggest that the gamma-aminobutyric acid (GABAergic) activity of the output system of the basal ganglia is globally increased by nigrostriatal denervation. We also analyzed the level of GAD67 mRNA expression in the superior colliculus, a structure that receives the inhibitory influence of the GABAergic neurons of the SNpr and that is involved in eye movement control. GAD67 mRNA expression was reduced in both MPTP-intoxicated monkeys, whether or not they received L-dopa therapy, and PD patients, compared to their respective controls. This decrease may result from the hyperactivity of the inhibitory nigrotectal pathway, but also from other influences since it was not corrected by L-dopa therapy. These changes may account for the slight ocular motor and visuospatial cognitive impairment occurring in PD, even after L-dopa therapy.
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PMID:Consequences of nigrostriatal denervation on the gamma-aminobutyric acidic neurons of substantia nigra pars reticulata and superior colliculus in parkinsonian syndromes. 861 87

Dyskinesias occur in the majority of patients with Parkinson's disease chronically treated with L-DOPA and also occur in several nonhuman primate species after 1-methyl-4phenyl-1,2,3,6-tetrahydropyridine (MPTP) and L-DOPA treatment. The common marmoset (Callithrix jacchus) shows parkinsonian motor deficits after MPTP administration, and we now report dyskinesias occurring in this species during chronic L-DOPA exposure. Marmosets rendered chronically parkinsonian after MPTP administration were treated orally with L-DOPA plus carbidopa for 3 weeks. After several days the animals began to display chorea, choreoathetosis, and dystonia. The severity of dyskinesias varied between the animals, with the most severely parkinsonian animals displaying the most dyskinetic movements. Each animal showed an idiosyncratic pattern of dyskinesias, which was highly reproducible. These L-DOPA-primed animals also received other D2 D1, and mixed D1/D2 agonist drugs. Quinpirole, bromocriptine, pergolide, apomorphine, and A-77636 all produce dyskinesias that were identical in character to those seen after L-DOPA administration, but the D1 agonist A-77636 gradually abolished dyskinesias while preserving its antiparkinsonian activity. The MPTP-treated marmoset provides a useful model in which to study dyskinesias in Parkinson's disease and to examine new therapeutic strategies aimed at alleviating this common side effect of chronic dopamine replacement therapy.
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PMID:Chronic L-DOPA administration induces dyskinesias in the 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine-treated common marmoset (Callithrix Jacchus). 874 92

The present review brings the survey of the most frequently used behavioural tests in experimental models of Parkinson's disease (PD). Although there is no spontaneous occurrence of parkinsonism in animals, several experimental animal models of PD have been developed to achieve the same clinical features in animals. The techniques employing neurotoxins in lesioning the nigrostriatal dopaminergic (DA) system have a large selectivity and reproducibility. The most frequently used neurotoxins are 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine (MPTP) and 6-hydroxydopamine (6-OHDA). MPTP-lesioned monkeys mimic best the symptomatology of PD in human patients while rats appear to be refractory to MPTP. For that reason, 6-OHDA is used to damage the substantia nigra in a rodent model. Behavioural tests of animals with nigrostriatal lesion represent valuable non-invasive methods for assessing the influence of damaged DA system on locomotor activity. The most frequently used experimental model of PD is the drug-evoked rotation in 6-OHDA unilaterally lesioned rats. This model produces well-defined and stable behavioural deficits. The rotation test is a useful parameter for evaluating imbalances of dopamine in both striata of the hemi-parkinsonian rat model. T-maze, treadmill running test or sensorimotor tests are used to evaluate spontaneous locomotor activity of lesioned animals. Skilled motor tasks measure the influence of dopamine-depleting lesions on complex motor acts. Transplantation of DA tissue into the striatum offers a new approach to the treatment of PD. Experimental models and behavioural tests are used to evaluate the extent of graft-induced recovery of MPTP- or 6-OHDA-lesioned animals. Different results obtained after the use of different tests reflect the level of graft integration into the host circuitry.
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PMID:Experimental models and behavioural tests used in the study of Parkinson's disease. 886 70

The aim of the present study was to analyse whether riluzole, a compound that interacts with the voltage-dependent sodium channel and impairs glutamatergic transmission, would exhibit a neuroprotective activity in a model of Parkinson's disease in the rat. Impaired skilled forelimb use, circling behavior, and altered dopaminergic metabolism of the mesotelencephalic system were evaluated in unilaterally 6-hydroxydopamine-lesioned rats. Riluzole was administered twice 15 min before, and 24 h after, the lesion. Riluzole reduced both the contralateral rotations induced by apomorphine and the ipsilateral ones elicited by amphetamine. Moreover, the decreased dopaminergic metabolism seen after 6-hydroxydopamine injection was attenuated in the riluzole-treated animals, at both the striatal and nigral levels. These biochemical and behavioral results demonstrate the ability of riluzole partially to protect the degeneration of the nigrostriatal dopaminergic neurons induced by the toxin 6-hydroxydopamine. Perhaps, the most striking evidence for the protective effect of riluzole was that this compound improved the skilled paw use, a complex sensorimotor behavior which is not easily ameliorated by palliative therapies such as dopaminergic grafts. These results extend previous data showing that riluzole counteracts the toxicity induced by 1-methyl-4-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenylpyridinium in rodent dopaminergic neurons. The use of riluzole may be considered of potential interest for the neuroprotective therapy of Parkinson's disease.
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PMID:Neuroprotective effects of riluzole on a model of Parkinson's disease in the rat. 889 66

To determine the effects of endogenous and exogenous melatonin on experimental models of Parkinson's disease (PD), Sprague-Dawley rats were exposed to intracerebroventricular implants of slow release melatonin, pinealectomy (PX), or constant light (LL) and then injected with central 6-hydroxydopamine (6-OHDA) or i.p. 1-methyl-4-phenyl,1-1,2,3,6-tetrahydropyridine (MPTP). The resulting impairment of motor function and related behavioural impairment were exacerbated by melatonin implantation, while PX and exposure to LL significantly reduced the severity of experimental PD. These results are consistent with previous work highlighting the importance of aberrant amine production in neurological disease and demonstrate that treatments that reduce endogenous melatonin bioavailability can ameliorate experimental PD. Furthermore, these findings illustrate that melatonin is not the universal remedy that it is currently claimed to be, and may pose considerable problems in neurological diseases characterised by dopamine degeneration.
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PMID:A therapeutic role for melatonin antagonism in experimental models of Parkinson's disease. 1040 6

The nocturnal sleep of three 1-Methyl, 4-phenyl, 1,2,3,6-tetrahydropyridine (MPTP) treated monkeys (one non-motor disabled and two severely motor disabled), while held in a primate chair was registered using a reversible system for head fixation and chronic recordings. Two electroencephalogram (EEG) channels, one electrooculogram (EOG) and one electromyogram (EMG) channel were monitored constantly and tape recorded during eight nights for posterior analyses. Subcutaneous temperature was registered each minute using a radio telemetry system. An analysis of sleep patterns and temperature parameters revealed lighter sleep, decreased amounts of slow wave and rapid eye movement (REM) sleep and lower temperature values in the two motor disabled MPTP-treated monkeys than in the non-motor disabled monkey. The temperature linear slope was negative in the case of one disabled monkey for just one night. Although the motor disability of the two monkeys was similar, their sleep organization patterns and temperatures slopes differed. The present study confirmed the differential vulnerability of the nigrostriatal system of monkeys to MPTP, suggesting that if a high cumulative dose was needed to reach stable motor alterations, the cumulative dose-effect of the toxin independent of the nigrostriatal system might be responsible for non-motor symptoms that also appear in Parkinson's disease besides the classic tetrad.
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PMID:Nocturnal sleep structure and temperature slope in MPTP treated monkeys. 1065 Nov 8

The activity of steroids was studied in 1-methyl-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioned retired breeder C57BL/6 male mice as a model of Parkinson's disease. Steroids were injected daily for 5 days before MPTP (4 injections, 15 mg/kg i.p., at 2 h intervals) and hormonal treatment continued for 5 more days. Mice that received 17beta-estradiol or progesterone or raloxifene (a selective estrogen receptor modulator) and MPTP had striatal concentrations of dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) similar to those in control animals, whereas mice that received MPTP alone or with 17alpha-estradiol (the isomer with weak estrogenic activity) had an extensive decrease of DA and its metabolites. These results suggest stereospecific prevention of MPTP-induced dopamine loss by 17beta-estradiol, which is also observed with progesterone and raloxifene.
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PMID:Ovarian steroids and raloxifene prevent MPTP-induced dopamine depletion in mice. 1067 83

Parkinson's disease no longer seems to be a disease entity caused by only one pathogenetic factor. The facile characterization of Parkinson's disease as a more or less isolated disorder of the dopaminergic system proves to be an unacceptable oversimplification of the pathology of the disease. Characteristically, not all dopaminergic systems of the central nervous system are involved in the degenerative process. In addition to the nigrostriatal dopaminergic pathway, parts of the glutamatergic, cholinergic, tryptaminergic, noradrenergic, adrenergic, serotonergic, and peptidergic neurons show serious cytoskeletal damage. In the light of these findings, drugs influencing these transmitter systems should be useful in the treatment of parkinsonian symptoms. For this reason, non-dopaminergic drugs are gaining more and more importance. Besides the theoretically interesting adenosine A2 receptor antagonists, budipine, a polyvalent potent new antiparkinsonian drug, has been tested in clinical studies. Budipine is a potent non-dopaminergic antiparkinsonian drug with pharmacological effects that are not comparable to those of conventional drugs applied in Parkinsonian pharmacotherapy. Budipine experimentally increased the brain content of noradrenaline, dopamine, serotonin, and histamine. The dopamine, serotonin, noradrenaline, gamma aminobutyric acid (GABA), and endorphine receptor affinities were not altered, but N-methyl-D-aspartate (NMDA) and sigma receptor affinities were increased as shown by in vivo and in vitro trials with budipine. MPTP (N-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine) and MPP+ antagonistic effects have also been demonstrated. Budipine also shows neuroprotective as well as symptomatic antiparkinsonian effects. In two randomized, double-blind, multicenter, placebo-controlled studies, relevant therapeutic effects have been observed in previously untreated, so-called "de-novo" parkinsonian patients and in subjects in later stages of the disease. Budipine significantly reduces akinesia, rigidity, and tremor. Optimal effects of budipine can be seen 4-6 weeks after starting treatment with this substance. Budipine can be added to all available antiparkinsonian drugs. An open, prospective, long-term study of 2532 patients with Parkinson's disease (Study BY701/01A) confirmed the favorable safety and tolerability profiles of budipine.
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PMID:Non-dopaminergic therapy in Parkinson's disease. 1099 61

Caspase-8 is a proximal effector protein of the tumor necrosis factor receptor family death pathway. In the present human postmortem study, we observed a significantly higher percentage of dopaminergic (DA) substantia nigra pars compacta neurons that displayed caspase-8 activation in Parkinson's disease (PD) patients compared with controls. In an in vivo experimental PD model, namely subchronically 1,2,3,6-tetrahydropyridine-treated mice, we also show that caspase-8 is indeed activated after exposure to this toxin early in the course of cell demise, suggesting that caspase-8 activation precedes and is not the consequence of cell death. However, cotreatment of 1-methyl-4-phenylpyridinium-intoxicated primary DA cultures with broad-spectrum and specific caspase-8 inhibitors did not result in neuroprotection but seemed to trigger a switch from apoptosis to necrosis. We propose that this effect is related to ATP depletion and suggest that the use of caspase inhibitors in pathologies linked to intracellular energy depletion, such as PD, should be cautiously evaluated.
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PMID:Caspase-8 is an effector in apoptotic death of dopaminergic neurons in Parkinson's disease, but pathway inhibition results in neuronal necrosis. 1126


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