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)

Parkinson disease (PD) is a neurodegenerative disorder characterized by a loss of the nigrostriatal dopaminergic neurons accompanied by a deficit in mitochondrial respiration. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that causes dopaminergic neurodegeneration and a mitochondrial deficit reminiscent of PD. Here we show that the infusion of the ketone body d-beta-hydroxybutyrate (DbetaHB) in mice confers partial protection against dopaminergic neurodegeneration and motor deficits induced by MPTP. These effects appear to be mediated by a complex II-dependent mechanism that leads to improved mitochondrial respiration and ATP production. Because of the safety record of ketone bodies in the treatment of epilepsy and their ability to penetrate the blood-brain barrier, DbetaHB may be a novel neuroprotective therapy for PD.
 ...
PMID:D-beta-hydroxybutyrate rescues mitochondrial respiration and mitigates features of Parkinson disease. 1297 74

The death of dopaminergic neurons induced by systemic administration of mitochondrial respiratory chain complex I inhibitors such as 1-methyl-4-phenylpyridinium (MPP(+); given as the prodrug 1-methyl-1,2,3,6-tetrahydropyridine) or the pesticide rotenone have raised the question as to whether this family of compounds are the cause of some forms of Parkinsonism. We have examined the neurotoxic potential of another complex I inhibitor, annonacin, the major acetogenin of Annona muricata (soursop), a tropical plant suspected to be the cause of an atypical form of Parkinson disease in the French West Indies (Guadeloupe). When added to mesencephalic cultures for 24 h, annonacin was much more potent than MPP(+) (effective concentration [EC(50)]=0.018 versus 1.9 microM) and as effective as rotenone (EC(50)=0.034 microM) in killing dopaminergic neurons. The uptake of [(3)H]-dopamine used as an index of dopaminergic cell function was similarly reduced. Toxic effects were seen at lower concentrations when the incubation time was extended by several days whereas withdrawal of the toxin after a short-term exposure (<6 h) arrested cell demise. Unlike MPP(+) but similar to rotenone, the acetogenin also reduced the survival of non-dopaminergic neurons. Neuronal cell death was not excitotoxic and occurred independently of free radical production. Raising the concentrations of either glucose or mannose in the presence of annonacin restored to a large extent intracellular ATP synthesis and prevented neuronal cell demise. Deoxyglucose reversed the effects of both glucose and mannose. Other hexoses such as galactose and fructose were not protective. Attempts to restore oxidative phosphorylation with lactate or pyruvate failed to provide protection to dopaminergic neurons whereas idoacetate, an inhibitor of glycolysis, inhibited the survival promoting effects of glucose and mannose indicating that these two hexoses acted independently of mitochondria by stimulating glycolysis. In conclusion, our study demonstrates that annonacin promotes dopaminergic neuronal death by impairment of energy production. It also underlines the need to address its possible role in the etiology of some atypical forms of Parkinsonism in Guadeloupe.
 ...
PMID:The mitochondrial complex I inhibitor annonacin is toxic to mesencephalic dopaminergic neurons by impairment of energy metabolism. 1452 88

This review focuses on the mechanisms of action and the injurious effect of complex I inhibitors, of which 1-methyl-4-phenylpyridinium ion (MPP(+)) is a well studied example. These compounds can be divided into two groups, i.e. competitive inhibitors with respect to ubiquinone, such as piericidine A, and non-competitive inhibitors such as rotenone. Complex I inhibitors such as MPP(+) have been reported to induce anatomical, behavioral, and biochemical changes similar to those seen in Parkinson's disease, which is characterized by nigrostriatal dopaminergic neuro-degeneration. Spectroscopic analyses and structure-activity relationship studies have indicated that the V-shaped structure of the rotenone molecule is critical for binding to the rotenone binding site on complex I. Many isoquinoline derivatives, some of them endogenous, are also complex I inhibitors. Many lines of evidence show that complex I inhibitors elicit neuronal cell death. Recently, it was reported that chronic and systemic exposure to low-dose rotenone reproduces the features of Parkinson's disease. This work further focused attention on compounds acting on mitochondria, such as MPP(+). In Guadeloupe, the French West Indies, patients with atypical parkinsonism or progressive supranuclear palsy are frequently encountered. These diseases seem to be associated with ingestion of tropical herbal teas or tropical fruits of the Annonaceae family, which contain complex I inhibitors such as benzylisoquinoline derivatives and acetogenins. Complex I inhibitors may not simply result in reactive oxygen species generation or ATP exhaustion, but may influence complex downstream signal transduction processes. An understanding of these changes would throw light on the ways in which complex I inhibitors induce a wide range of abnormalities.
 ...
PMID:MPP+ analogs acting on mitochondria and inducing neuro-degeneration. 1452 66

Ketones were first discovered in the urine of diabetic patients in the mid-19th century; for almost 50 years thereafter, they were thought to be abnormal and undesirable by-products of incomplete fat oxidation. In the early 20th century, however, they were recognized as normal circulating metabolites produced by liver and readily utilized by extrahepatic tissues. In the 1920s, a drastic "hyperketogenic" diet was found remarkably effective for treatment of drug-resistant epilepsy in children. In 1967, circulating ketones were discovered to replace glucose as the brain's major fuel during the marked hyperketonemia of prolonged fasting. Until then, the adult human brain was thought to be entirely dependent upon glucose. During the 1990s, diet-induced hyperketonemia was found therapeutically effective for treatment of several rare genetic disorders involving impaired neuronal utilization of glucose or its metabolic products. Finally, growing evidence suggests that mitochondrial dysfunction and reduced bioenergetic efficiency occur in brains of patients with Parkinson's disease (PD) and Alzheimer's disease (AD). Because ketones are efficiently used by mitochondria for ATP generation and may also help protect vulnerable neurons from free radical damage, hyperketogenic diets should be evaluated for ability to benefit patients with PD, AD, and certain other neurodegenerative disorders.
 ...
PMID:Ketones: metabolism's ugly duckling. 1460 65

Exposure of rats to the pesticide and complex I inhibitor rotenone reproduces features of Parkinson's disease, including selective nigrostriatal dopaminergic degeneration and alpha-synuclein-positive cytoplasmic inclusions (Betarbet et al., 2000; Sherer et al., 2003). Here, we examined mechanisms of rotenone toxicity using three model systems. In SK-N-MC human neuroblastoma cells, rotenone (10 nm to 1 microm) caused dose-dependent ATP depletion, oxidative damage, and death. To determine the molecular site of action of rotenone, cells were transfected with the rotenone-insensitive single-subunit NADH dehydrogenase of Saccharomyces cerevisiae (NDI1), which incorporates into the mammalian ETC and acts as a "replacement" for endogenous complex I. In response to rotenone, NDI1-transfected cells did not show mitochondrial impairment, oxidative damage, or death, demonstrating that these effects of rotenone were caused by specific interactions at complex I. Although rotenone caused modest ATP depletion, equivalent ATP loss induced by 2-deoxyglucose was without toxicity, arguing that bioenergetic defects were not responsible for cell death. In contrast, reducing oxidative damage with antioxidants, or by NDI1 transfection, blocked cell death. To determine the relevance of rotenone-induced oxidative damage to dopaminergic neuronal death, we used a chronic midbrain slice culture model. In this system, rotenone caused oxidative damage and dopaminergic neuronal loss, effects blocked by alpha-tocopherol. Finally, brains from rotenone-treated animals demonstrated oxidative damage, most notably in midbrain and olfactory bulb, dopaminergic regions affected by Parkinson's disease. These results, using three models of increasing complexity, demonstrate the involvement of oxidative damage in rotenone toxicity and support the evaluation of antioxidant therapies for Parkinson's disease.
 ...
PMID:Mechanism of toxicity in rotenone models of Parkinson's disease. 1464 67

Genetic or functional mitochondrial alterations can result in the initiation of cell death programs that are believed to contribute to cell death in diabetes, ageing and neurodegenerative disorders. Mitochondria are being considered the main link between cellular stress signals activated during acute and chronic nerve cell injury, and the execution of nerve cell death. This second function of mitochondria is regulated by several families of proteins that can trigger an increase in permeability of the outer and/or inner mitochondrial membrane. One example of this is the formation of the mitochondrial permeability transition pore (MPTP). This process can trigger the release of cell death-inducing factors from mitochondria, as well as a dissipation of the mitochondrial transmembrane potential, depletion of ATP, and increased free radical formation. Among the factors released from mitochondria are cytochrome c, the apoptosis inductor factor (AIF), and caspases. We review the role of the MPTP in diverse physiological and pathological processes, including neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis (ALS). The design of drugs that could interfere with the functions of the MPTP could allow novel therapeutic approaches for the treatment of acute and chronic nerve cell injury.
 ...
PMID:Mitochondrial control of neuron death and its role in neurodegenerative disorders. 1464 78

We present for discussion a possible molecular mechanism explaining the formation of reactive oxygen species involved in the neurodegenerative process of dopaminergic system in Parkinson's disease. This new hypothesis involves one-electron reduction of aminochrome to o-semiquinone radical, which seems to be the reaction responsible for neurodegenerative process of dopaminergic system. Leukoaminochrome o-semiquinone is extremely reactive with oxygen, which reoxidizes by reducing oxygen to superoxide radicals. Superoxide radicals enzymatically or spontaneously dismutate to dioxygen and hydrogen peroxide which is a precursor of hydroxyl radicals. ESR-experiments have showed that aminochrome o-semiquinone is extremely reactive in the presence of oxygen compared to dopamine o-semiquinone. In addition, the antioxidant enzymes superoxide dismutase and catalase play a prooxidant role by increasing the autoxidation rate and formation of superoxide radicals. One electron reduction of aminochrome to o-semiquinone can be performed by flavoenzymes which use NADPH and NADH as electron donator. The ability of aminochrome o-semiquinone to autoxidize in the presence of oxygen gives rise to a redox cycling process which will continue until oxygen, NADH and/or NADPH are depleted. Depletion of NADPH will prevent glutathione reductase from reducing glutathione, which is one of the main antioxidants in the cell. In addition depletion of NADH will prevent the formation of ATP in the electron transport chain in the mitochondria. Two antioxidants, probably, neuroprotective reactions are also discussed.
 ...
PMID:The possible role of one-electron reduction of aminochrome in the neurodegenerative process of the dopaminergic system. 1471 70

Oxidative stress is now recognized as accountable for redox regulation involving reactive oxygen species (ROS) and reactive nitrogen species (RNS). Its role is pivotal for the modulation of critical cellular functions, notably for neurons astrocytes and microglia, such as apoptosis program activation, and ion transport, calcium mobilization, involved in excitotoxicity. Excitotoxicity and apoptosis are the two main causes of neuronal death. The role of mitochondria in apoptosis is crucial. Multiple apoptotic pathways emanate from the mitochondria. The respiratory chain of mitochondria that by oxidative phosphorylation, is the fount of cellular energy, i.e. ATP synthesis, is responsible for most of ROS and notably the first produced, superoxide anion (O(2)(;-)). Mitochondrial dysfunction, i.e. cell energy impairment, apoptosis and overproduction of ROS, is a final common pathogenic mechanism in aging and in neurodegenerative disease such as Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). Nitric oxide (NO(;)), an RNS, which can be produced by three isoforms of NO-synthase in brain, plays a prominent role. The research on the genetics of inherited forms notably ALS, AD, PD, has improved our understanding of the pathobiology of the sporadic forms of neurodegenerative diseases or of aging of the brain. ROS and RNS, i.e. oxidative stress, are not the origin of neuronal death. The cascade of events that leads to neurons, death is complex. In addition to mitochondrial dysfunction (apoptosis), excitotoxicity, oxidative stress (inflammation), the mechanisms from gene to disease involve also protein misfolding leading to aggregates and proteasome dysfunction on ubiquinited material.
 ...
PMID:Neurodegenerative diseases and oxidative stress. 1473 60

Tolcapone and entacapone are catechol-O-methyltransferase (COMT) inhibitors used as adjuncts to levodopa in the treatment of Parkinson's disease (PD). The use of tolcapone has been limited by its hepatotoxicity, the cause of which remains uncertain. Tolcapone compound is an uncoupler of mitochondrial respiration in isolated mitochondria and this action may be relevant to its effect on liver function. We have examined the actions of COMT inhibitors on cultured cells, comparing them with those of the classical uncoupler carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), in order to provide insight into their mechanism of potential toxicity. Tolcapone and FCCP were shown to be toxic to human neuroblastoma SH-SY5Y cells and caused a profound reduction in ATP synthesis. Entacapone was not toxic to SH-SY5Y. Tolcapone and FCCP were shown to be equally toxic to cells depleted of mtDNA and thus devoid of a functional respiratory chain. This study demonstrates that tolcapone markedly inhibits ATP synthesis in cultured cells mirroring the effects of a classical uncoupler. However its toxicity may also involve a mechanism independent of its effects upon oxidative phosphorylation.
 ...
PMID:Differences in toxicity of the catechol-O-methyl transferase inhibitors, tolcapone and entacapone to cultured human neuroblastoma cells. 1497 80

The massive activation of poly(ADP-ribose) polymerase-1 (PARP-1) by DNA-damaging stimuli, such as exposure to reactive oxygen species (ROS), can lead to cell injury via severe, irreversible depletion of the NAD and ATP pool, and PARP-1 inhibitors have been expected to rescue neurons from degeneration in a number of disease models. We have recently identified 2-[3-[4-(4-chlorophenyl)-1-piperazinyl] propyl]-4(3H)-quinazolinone (FR255595) as a novel and potent PARP-1 inhibitor through structure-based drug design and high-throughput screening. This compound potently inhibited PARP activity with an IC(50) value of 11 nM and was orally active and highly brain penetrable. Here, we show that prevention of PARP activation by FR255595 protects against both ROS-induced cells injury in vitro and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal dopaminergic damage in an in vivo Parkinson's disease (PD) model. In cell death models in vitro, exposure of hydrogen peroxide induced cell death with PARP overactivation in PC12 cells and SH-SY5Y cells, and pre- and post-treatment with FR255595 (10(-9)-10(-5) M) significantly reduced PARP activation and cell death. In mouse MPTP model, MPTP (20 mg/kg i.p.) intoxication lead to PARP activation and cell damage in the nigrostriatal dopaminergic pathway, which was significantly ameliorated by oral administration of FR255595 (10-32 mg/kg), both in the substantia nigra and in the striatum via marked reduction of PARP activation, even with delayed treatment. These findings clearly indicate that the novel PARP-1 inhibitor FR255595 exerts neuroprotective effect through its potent PARP-1 inhibitory actions in PD model, suggesting that the drug could be an attractive candidate for several neurodegenerative disorders, including PD.
 ...
PMID:Neuroprotective effects of a novel poly(ADP-ribose) polymerase-1 inhibitor, 2-[3-[4-(4-chlorophenyl)-1-piperazinyl] propyl]-4(3H)-quinazolinone (FR255595), in an in vitro model of cell death and in mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of Parkinson's disease. 1498 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>