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 isoprenoid pathway produces four key metabolites important in cellular function--digoxin (endogenous membrane Na(+)-K+ ATPase inhibitor), dolichol (important in N-glycosylation of proteins), ubiquinone (free-radical scavenger), and cholesterol (component of cellular membranes). This study assessed the changes in the isoprenoid pathway and the consequences of its dysfunction in Parkinson's disease (PD). There was an elevation in plasma HMG CoA reductase activity, serum digoxin and dolichol levels, and a reduction in serum magnesium, RBC membrane Na(+)-K+ ATPase activity, and serum ubiquinone levels. Serum tryptophan, serotonin, strychnine, nicotine, and quinolinic acid were elevated, while tyrosine, morphine, dopamine, and noradrenaline were decreased. The total serum glycosaminoglycans (GAG) and glycosaminoglycan fractions (except chondroitin sulphates and hyaluronic acid), the activity of GAG degrading enzymes, carbohydrate residues of serum glycoproteins, the activity of glycohydrolase-beta galactosidase, and serum glycolipids were elevated. HDL cholesterol was reduced and free fatty acids increased. The RBC membrane glycosaminoglycans, hexose and fucose residues of glycoproteins and cholesterol were reduced, while phospholipid was increased. The activity of all serum free-radical scavenging enzymes, concentration of glutathione, alpha tocopherol, iron binding capacity, and ceruloplasmin decreased significantly in PD, while the concentration of serum lipid peroxidation products and nitric oxide increased. A dysfunctional isoprenoid pathway and related cascade are important in the pathogenesis of Parkinson's disease. A hypothalamic digoxin mediated model for Parkinson's disease is also postulated.
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PMID:Hypothalamic digoxin-mediated model for Parkinson's disease. 1285 80

There is growing evidence that oxidative phosphorylation (OXPHOS) generates reactive oxygen and nitrogen species within mitochondria as unwanted byproducts that can damage OXPHOS enzymes with subsequent enhancement of free radical production. The accumulation of this oxidative damage to mitochondria in brain is thought to lead to neuronal cell death resulting in neurodegeneration. The predominant reactive nitrogen species in mitochondria are nitric oxide and peroxynitrite. Here we show that peroxynitrite reacts with mitochondrial membranes from bovine heart to significantly inhibit the activities of complexes I, II, and V (50-80%) but with less effect upon complex IV and no significant inhibition of complex III. Because inhibition of complex I activity has been a reported feature of Parkinson's disease, we undertook a detailed analysis of peroxynitrite-induced modifications to proteins from an enriched complex I preparation. Immunological and mass spectrometric approaches coupled with two-dimensional PAGE have been used to show that peroxynitrite modification resulting in a 3-nitrotyrosine signature is predominantly associated with the complex I subunits, 49-kDa subunit (NDUFS2), TYKY (NDUFS8), B17.2 (17.2-kDa differentiation associated protein), B15 (NDUFB4), and B14 (NDUFA6). Nitration sites and estimates of modification yields were deduced from MS/MS fragmentograms and extracted ion chromatograms, respectively, for the last three of these subunits as well as for two co-purifying proteins, the beta and the d subunits of the F1F0-ATP synthase. Subunits B15 (NDUFB4) and B14 (NDUFA6) contained the highest degree of nitration. The most reactive site in subunit B14 was Tyr122, while the most reactive region in B15 contained 3 closely spaced tyrosines Tyr46, Tyr50, and Tyr51. In addition, a site of oxidation of tryptophan was detected in subunit B17.2 adding to the number of post-translationally modified tryptophans we have detected in complex I subunits (Taylor, S. W., Fahy, E., Murray, J., Capaldi, R. A., and Ghosh, S. S. (2003) J. Biol. Chem. 278, 19587-19590). These sites of oxidation and nitration may be useful biomarkers for assessing oxidative stress in neurodegenerative disorders.
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PMID:Oxidative damage to mitochondrial complex I due to peroxynitrite: identification of reactive tyrosines by mass spectrometry. 1285 34

The membrane composition and the isoprenoid pathway metabolites important in maintaining cell membrane integrity was studied in neurological and psychiatric disorders. The results indicate alteration in cholesterol:phospholipid ratio of the RBC membrane which is increased in glioma, schizophrenia, and bipolar mood disorder (MDP); decreased in multiple sclerosis and Parkinson's disease; and not significantly altered in epilepsy. The concentration of total glycosaminoglycans (GAG), hexose, and fucose decreased in the RBC membrane and increased in the serum. The RBC membrane Na+-K+ ATPase activity was reduced and serum HMG CoA reductase activity was increased. There were increased serum levels of digoxin, cholesterol, and dolichol and decreased levels of ubiquinone. The serum magnesium and tyrosine levels were reduced and tryptophan increased. The results indicate a defect in membrane formation and a decreased membrane Na+-K+ ATPase activity in all the disorders studied. The results are discussed, and a hypothesis regarding the relationship between these disorders and defective membrane architecture and membrane Na+-K+ ATPase inhibition is presented.
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PMID:Isoprenoid pathway-related membrane dysfunction in neuropsychiatric disorders. 1458 55

Psychiatric abnormalities have been described in primary neurological disorders like multiple sclerosis, primary generalized epilepsy, Parkinson's disease, subacute sclerosing panencephalitis (SSPE), central nervous system glioma, and syndrome X with vascular dementia. It was therefore considered pertinent to compare monoamine neurotransmitter pattern in schizophrenia with those in the disorders described above. The end result of neurotransmission is changes in membrane Na(+)-K+ ATPase activity. Membrane Na(+)-K+ ATPase inhibition can lead to magnesium depletion, which can lead to an upregulated isoprenoid pathway. The isoprenoid pathway produces three important metabolites--digoxin, an endogenous membrane Na(+) -K+ ATPase inhibitor; ubiquinone, a membrane antioxidant and component of mitochondrial electron transport chain; and dolichol, important in N-glycosylation of protein. The serum/plasma levels of digoxin, dolichol, ubiquinone, magnesium, HMG CoA reductase activity, and RBC Na(+)-K+ ATPase activity were estimated in all these disorders. The result showed that the concentration of serum tryptophan and serotonin was high and serum tyrosine, dopamine, adrenaline, and noradrenaline low in all the disorders studied. The plasma HMG CoA reductase activity, serum digoxin, and serum dolichol levels were high and serum ubiquinone levels, serum magnesium, and RBC Na(+)-K+ ATPase activity were low in all the disorders studied. The significance of these changes in the pathogenesis of syndrome X, multiple sclerosis, primary generalized epilepsy, schizophrenia, SSPE, and Parkinson's disease is discussed in the setting of the interrelationship between these disorders documented in literature.
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PMID:Schizoid neurochemical pathology-induced membrane Na(+)-K+ ATPase inhibition in relation to neurological disorders. 1460 43

The findings of a negative association between past maize (Zea mays) production and current Parkinson's disease mortality by each prefecture in Japan tends to support the hypothesis that the nutritional condition that causes niacin deficiency might protect people from Parkinson's disease. Specifically, the negative association between both the area planted for dried corn in 1960, 1970 or 1977 and the area planted for sweet corn in 1960 and age-adjusted death rates for Parkinson's disease is ecological evidence supporting the hypothesis. Extending the analysis to other cultivated crops, even stronger negative associations of age-adjusted death rates for Parkinson's disease and cultivation of rice and soybeans were found, but associations were not significant for a large variety of vegetables. The findings for soybean and rice are attributed to the correspondence (co-linearity) of cultivation of these other two seed-crops with maize. Hence, further testing of the theory of niacin deprivation and prevention of Parkinson's disease finds some circumstantial support in the cultivation patterns of a grain of poor niacin and tryptophan availability.
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PMID:Retrospective study of preventive effect of maize on mortality from Parkinson's disease in Japan. 1467 69

Parkinson's disease is associated with the deposition and accumulation of alpha-synuclein fibrils in the brain. A30P and A53T mutations have been linked to the early-onset familial disease state. Time-resolved tryptophan fluorescence energy-transfer measurements have been used to probe the structures of pseudo-wild-type and mutant (A30P) alpha-synucleins at physiological pH (7.4), in acidic pH (4.4) solutions, and in the presence of SDS micelles, a membrane mimic. Fluorescent donor-energy acceptor (DA) distance distributions for six different tryptophan/3-nitro-tyrosine pairs reveal the presence of compact, intermediate, and extended conformations of the protein. CD spectra indicate that the protein develops substantial helical structure in the presence of SDS micelles. DA distributions show that micelles induce compaction in the N-terminal region and expansion of the acidic C terminus. In acidic solutions, there is an increased population of collapsed structures in the C-terminal region. Energy-transfer measurements demonstrate that the average DA distances for the W4-Y19 and Y19-W39 pairs are longer in one of the two disease-related mutants (A30P).
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PMID:Alpha-synuclein structures from fluorescence energy-transfer kinetics: implications for the role of the protein in Parkinson's disease. 1553 28

Homeostatic interactions between dopamine and glutamate are central to the normal physiology of the basal ganglia. This relationship is altered in Parkinsonism and in levodopa-induced dyskinesias (LID), resulting in an upregulation of corticostriatal glutamatergic function. Kynurenic acid (KYNA), a tryptophan metabolite with antagonist activity at ionotropic glutamate receptors and the capability to inhibit glutamate release presynaptically, might therefore be of therapeutic value in LID. To evaluate this hypothesis, we used a pharmacological tool, the kynurenine 3-hydroxylase inhibitor Ro 61-8048, which raises KYNA levels acutely. Ro 61-8048 was tested in MPTP cynomolgus monkeys with a stable parkinsonian syndrome and reproducible dyskinesias after each dose of levodopa. Serum and CSF concentrations of KYNA and its precursor kynurenine increased dose-dependently after Ro 61-8048 administration, alone or in combination with levodopa. Coadministration of Ro 61-8048 with levodopa produced a moderate but significant reduction in the severity of dyskinesias while maintaining the motor benefit. These results suggest that elevation of KYNA levels through inhibition of kynurenine 3-hydroxylase constitutes a promising novel approach for managing LID in Parkinson's disease.
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PMID:Effect of kynurenine 3-hydroxylase inhibition on the dyskinetic and antiparkinsonian responses to levodopa in Parkinsonian monkeys. 1595 16

Objective--Excitatory amino acid receptors are involved in the normal physiology of the brain, and may play a role in the pathogenesis of neurological disorders such as Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, etc. It has been demonstrated that the blockade of one of these receptors ameliorates the symptoms of experimental allergic encephalomyelitis, an animal model of multiple sclerosis (MS). In a recent study, a decreased level of kynurenic acid was found in the cerebrospinal fluid of patients with MS. The only known endogenous excitotoxin receptor antagonist is the tryptophan metabolite kynurenic acid. Another metabolite is quinolinic acid, which exerts different action: it is an excitotoxin receptor agonist. The ratio of these two metabolites is determined by the activities of kynurenine aminotransferase I and II (KAT I and KAT II). In this study, we measured the activities of these enzymes and the concentration of kynurenic acid in the red blood cells (RBC) and in the plasma of patients with MS. KAT activities were detected both in the RBC and in the plasma. As compared with the control subjects, the KAT I and KAT II activities were significantly higher in the RBC of the patients. The concentration of kynurenic acid is elevated in the plasma of MS patients, and there is a tendency to an elevation in the RBC. These changes may indicate a compensatory protective mechanism against excitatory neurotoxic effects. Our data demonstrate the involvement of the kynurenine system in the pathogenesis of MS, which may predict a novel therapeutic intervention.
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PMID:Kynurenine metabolism in multiple sclerosis. 1600 34

Kynurenine (KYN) is an intermediate in the pathway of the metabolism of tryptophan to nicotinic acid. KYN is formed in the mammalian brain (40%) and is taken up from the periphery (60%), indicating that it can be transported across the blood-brain barrier (BBB). In the brain, KYN can be converted to two other components of the pathway: the neurotoxic quinolinic acid (QUIN) and the neuroprotective kynurenic acid (KYNA). QUIN is probably the most widely studied metabolite of KYN, because it may cause excitotoxic neuronal cell loss and convulsions by interacting with the N-methyl-D-aspartate (NMDA) receptor complex, a type of glutamate receptor. KYNA is another metabolite of KYN; its synthesis is catalysed by KYN aminotransferases. This is the only known endogenous NMDA receptor inhibitor, which can act at the glycine site on the receptor complex. Furthermore, KYNA non-competitively inhibits alpha7 nicotinic acetylcholine presynaptic receptors (nAChRs), inhibiting glutamate release, and regulates the expression of alpha4beta2 nAChR. It is well-known that the activation of excitatory amino acid (EAA) receptors can play a role in a number of neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease, stroke and epilepsy. Various studies have been made of whether the EAA receptor antagonist KYNA can exert a therapeutic effect in these neurological disorders. It has been established that KYNA has only a very limited ability to cross the BBB. Other KYNA derivatives have been synthesised (e.g. glucosamine-KYNA, 4-chloro-KYNA and 7-chloro-KYNA), which are well transported across the BBB and act on the glutamate receptors. Moreover, it has been demonstrated that probenecid, a known inhibitor of the transport of organic acids (e.g. KYNA), increases the cerebral concentration of KYNA. There is another new perspective to the maintenance of a high level of KYNA in the brain: the use of enzyme inhibitors, which can block the synthesis of the neurotoxic QUIN. These are some of the most promising possibilities as novel therapeutic strategies for the treatment of neurodegenerative diseases, in which the hyperactivation of amino acid receptors could be involved. The presence and importance of KYN derivatives in the periphery are also discussed in the light of recent publications.
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PMID:Role of kynurenines in the central and peripheral nervous systems. 1618 Nov 18

Enrichment of diet with Nicotinamide in the West was introduced in the 1940s to prevent the dietary deficiency disorder Pellagra. Pellagra was caused by a particular form of poor vegetarian diet leading to Nicotinamide and Tryptophan deficiency. Arguably Pellagra would have disappeared if dietary measures suggested at the time had been implemented before Nicotinamide was even discovered. Diets may sometimes now be too high in selected pyridines and inadvertently we have exchanged one neurodegenerative disease for another. Parkinson's disease triggered in contrast to Pellagra by a particular form of rich omnivorous diet. Moderation of Nicotinamide intake would be easy to begin with compared with other dietary manipulations as there is no behavior change necessary for individuals. A substantial amount of Nicotinamide can be removed when and where there is too much that has been introduced artificially and inserted where there is too little because meat is unaffordable.
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PMID:Nicotinamide: a double edged sword. 1618 23


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