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

In an attempt to define neurochemically the part played by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as a potential Parkinson's disease-inducing neurotoxin, we measured the tissue concentrations of the monoamines dopamine, noradrenaline and serotonin in 45 brain regions in nine rhesus monkeys (Macaca mulatta) receiving repeated intramuscular injections of a total amount of 2.1-7.5 mg/kg MPTP-HCl. Four monkeys treated with MPTP during a period of one to five weeks developed permanent Parkinsonism, and five animals receiving the neurotoxin during a period of two to seven months remained asymptomatic. We found that, compared with the distribution pattern established in the brain of seven normal (drug-free) rhesus monkeys, in the MPTP-treated monkeys none of the three major brain monoamine neuron systems was completely resistant to the neurotoxin. In addition, each brain monoamine had a characteristic regional pattern of MPTP-induced changes. As expected, the most significant alterations were found within the nigrostriatal dopamine system, i.e. profound dopamine loss in caudate nucleus, putamen and substantia nigra. However, many extrastriatal regions of the subcortex and brainstem also suffered significant loss of dopamine, with the noradrenaline loss in the regionally subdivided brainstem being less widespread, and the serotonin levels least affected. Thus, in subcortex/brainstem the ranking order of sensitivity to MPTP was: dopamine greater than noradrenaline much greater than serotonin. In the cerebral (neo- and limbic) cortex, all three monoamine neuron systems suffered widespread statistically significant losses. The ranking order of MPTP sensitivity of the cortical monoamines was: noradrenaline greater than serotonin greater than dopamine. In the cerebellar cortex, dopamine and noradrenaline concentrations were significantly reduced, whereas the serotonin level remained unchanged. A remarkable observation was that many of the subcortical and cortical changes found in the symptomatic monkeys were also found in the asymptomatic animals. Our data are compatible with several possible mechanisms by which MPTP may have produced the observed patterns of monoamine loss in the brain of the rhesus monkey. Our study demonstrates that in the rhesus monkey MPTP mimicked, in addition to the profound striatal dopamine loss, some of the extrastriatal dopamine, noradrenaline and serotonin changes often seen in the brain of patients with idiopathic Parkinson's disease. However, using our treatment regimen, we have not been able to reproduce in the rhesus monkey the inter-regional pattern of striatal dopamine loss typical of idiopathic Parkinson's disease, i.e. a significantly greater loss of dopamine in the putamen compared with the caudate nucleus.
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PMID:Effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine on the regional distribution of brain monoamines in the rhesus monkey. 175 53

Progress in Parkinson's disease research has been rapid in recent years from both a scientific and clinical point of view. The MPTP discovery represented a milestone in the knowledge of the biochemical mechanism underlying degeneration of dopaminergic neurons of the nigrostriatal pathway. Recent life and scientific events have initiated, even ironically, new trends in the mechanism of MPTP toxicity. The role of excitatory amino acids, particularly of NMDA receptors, in this toxicant-induced degenerative process, seems to be crucial. If this new finding is further confirmed by studies on primates, the animal species most sensitive to the neurotoxin, research into Parkinson's disease might move in other directions, useful in both treatment and prevention.
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PMID:In memoriam Richard Heikkila. The MPTP story: irony creeps back in. 177 76

MPTP administration, preferably to mice and primates, induces a selective damage of substantia nigra dopaminergic cells. Intrinsic mechanisms mediating MPTP induced toxicity, remain still under evaluation. There are very few semiological differences between Parkinson's disease (PD) and MPTP parkinsonism, but significant biochemical and neuropathological differences have been reported between these two entities. However, at the moment it represents the best model of Parkinson's disease available for the study of the basal ganglia function. In addition it could be a useful tool for a better understanding of mechanisms involved in neuronal death and regeneration. The present paper, summarize the real knowledge about the mechanism by which MPTP induces neuronal toxicity, the differences reported between PD and MPTP parkinsonism and finally its application for research.
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PMID:[Parkinsonism induced by MPTP as an experimental model of Parkinson disease: similarities and differences]. 179 5

The study of subtle changes in motor and cognitive function after exposure to MPTP might serve as a guide to the very earliest stages of Parkinson's disease. Studies in nonhuman primates and man exposed to MPTP who remained asymptomatic or recovered completely are reviewed. The question of the relationship between the degree and extent of damage to the nigrostriatal dopamine system and changes in motor and cognitive (behavioral) function is addressed. What guidance they provide in the study of subclinical or preclinical Parkinson's disease is discussed.
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PMID:Subclinical damage to the nigrostriatal dopamine system by MPTP as a model of preclinical Parkinson's disease: a review. 180 34

The cause of dopamine cell death in Parkinson's disease remains unknown. Present interest centres on the possible involvement of a toxin mediated mechanism such as that produced, by MPTP. In post-mortem studies there is evidence in the substantia nigra for an on-going toxic process involving increased lipid peroxidation, altered iron metabolism and impairment of mitochondrial function at the level of complex I. Although the precise relationship between these biochemical changes is not known, present evidence points to oxidative stress as an important factor contributing to neuronal loss. Altered mitochondrial function and increased iron levels may not initiate Parkinson's disease but rather act to accelerate cell death. Future strategies for the treatment of Parkinson's disease should be aimed at preventing oxidative stress and stopping or slowing the progression of the underlying pathology.
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PMID:Oxidative stress as a cause of Parkinson's disease. 180 37

Common marmosets were given a subcutaneous injection of MPTP (1.25-2.5 mg/kg twice a week) for 5 or 10 consecutive months and were sacrificed after a survival time of 6 months or 15 days, respectively. The parkinsonian symptoms were not very marked at the time of sacrifice but there was a strong decrease of dopamine and, to a lesser extent, of its metabolites in the striatum and in some extrastriatal regions. There was also a profound loss of serotonin in the striatum and in all of the extrastriatal regions analyzed, which was still highly significant 6 months after discontinuation of MPTP treatment. The results suggest that the selected dosage schedule produces a widespread and lasting neuronal degeneration closely resembling the neurochemical pathology of Parkinson's disease.
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PMID:Extensive loss of brain dopamine and serotonin induced by chronic administration of MPTP in the marmoset. 181 20

Systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) gives rise to motor deficits in humans and other primates which closely resemble those seen in patients with Parkinson's disease. These deficits are associated with a relatively selective loss of cells in the pars compacta of the substantia nigra and severe reductions in the concentrations of dopamine, noradrenaline and serotonin in the striatum. Similarly, in mice of various different strains the administration of MPTP also induces a marked loss of dopaminergic cells with severe depletion of biogenic amines, but higher doses of MPTP are required to produce these effects in mice than in primates. This review summarises advances made in understanding the biochemical events which underlie the remarkable neurotoxic action of MPTP. Major steps in the expression of neurotoxicity involve the conversion of MPTP to the toxic agent 1-methyl-4-phenylpyridinium ion (MPP+) by type B monoamine oxidase (MAO-B) in the glia, specific uptake of MPP+ into the nigro-striatal dopaminergic neurones, the intraneuronal accumulation of MPP+, and the neurotoxic action of MPP+. This is exerted mainly through the inhibition of the enzymes of the respiratory chain (Complex I), the disturbance of Ca2+ homeostasis, and possibly by the formation of free radicals. The relevance of the MPTP model to idiopathic Parkinson's disease is discussed.
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PMID:MPTP mechanisms of neurotoxicity and their implications for Parkinson's disease. 181 82

The near IR emission at 1270 nm following pulsed laser excitation of methylene blue in deuterium oxide, was used to study the interaction of a singlet molecular oxygen (1O2) with (i) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its oxidation products, and (ii) biosubstrates of relevance in Parkinson's disease. Steady state irradiation of methylene blue and MPTP led to a product with an absorption profile consistent with that of 1-methyl-4-phenyl-2,3-dihydropyridinium ion. This may suggest that even if monoamine oxidase enzyme activity is inhibited by the use of drugs such as Deprenyl and Paragyline the underlying conversion of MPTP to its neurotoxic oxidation product via 1O2 may still take place.
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PMID:Chemically induced Parkinson's disease. III: A study of a possible role of singlet molecular oxygen in Parkinson's disease. 181 61

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a well-known model substance for inducing in humans and monkeys a severe extrapyramidal syndrome similar to Parkinson's disease. The neurotoxic action of MPTP can be exerted not only in adult animals but also during fetal development by diaplacental passage. Here we show that, during the gestation period of mice, the placenta is another important target organ of MPTP cytotoxicity. Pregnant NMRI mice on gestation day 15 received a single intraperitoneal dose of 20, 40, or 60 mg/kg MPTP. Developmental parameters of the fetuses and the placentas were determined on gestation day 18. Placental weight was consistently reduced in all experimental groups. Histology showed conspicuous alterations of the labyrinth layer; at 20 mg/kg MPTP there was already a significant reduction of the trabecular diameters and from 40 mg/kg onwards, severe necrosis of the syncytial trophoblast cells. In addition, there were necrotic alterations of the cells of the visceral yolk sac. The toxic effects are confined to the placenta at the doses used in the present experiments, leading at just 60 mg/kg to a marked placental insufficiency syndrome.
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PMID:Placental toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice. 182 98

Current long-term treatment of Parkinson's disease is inadequate, and improved symptomatic and neuroprotective therapies are needed. Recent interest has focused on the use of antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor in Parkinson's disease. Abnormally increased activity of the subthalamic nucleus is postulated to play a central pathophysiological role in the signs of Parkinson's disease, and NMDA antagonists may provide a means of decreasing this activity selectively. Like dopaminergic agonists, NMDA antagonists can reverse the akinesia and rigidity associated with monoamine depletion or neuroleptic-induced catalepsy. Very low doses of NMDA antagonists markedly potentiate the therapeutic effects of dopaminergic agonists. There is evidence that the beneficial effects of anticholinergic drugs and amantadine may be mediated, in part, by NMDA receptor blockade. Moreover, NMDA antagonists provide profound protection of dopaminergic neurons of the substantia nigra in the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and methamphetamine models of Parkinson's disease. The clinical use of NMDA antagonists may prove useful in Parkinson's disease to treat symptoms and retard disease progression.
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PMID:N-methyl-D-aspartate antagonists in the treatment of Parkinson's disease. 147 53


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