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 authors describe the results of biochemical analysis carried out on 28 patients with Parkinson's disease who had been treated by L-dopa. Twenty of them showed either no abnormal movements at all or very few, eight others had considerable dyskinesia. Biochemical analysis of the urinary degradation products of L-Dopa revealed the existence of a swing in the degradation of dopamine towards 4-O-methylate derivatives in dyskinetic patients (significant difference at .01). The results confirm those obtained in their initial analysis carried out in 1973. The authors express the view that abnormal movements while under L-Dopa treatment are dependent on two factors: one, the hypersensitivity of dopaminergic reception, the other, the greater or lesser preponderance of the COMT isozyme giving rise to 4-O-methylates;
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PMID:[Abnormal movements of patients with Parkinsonism treated with L-dopa and anomalies of dopamine metabolism]. 84 19

The introduction of levodopa in the treatment of Parkinson's disease had modified both the prognosis and the current concepts of the disease, Although levodopa remains the most potent drug for the treatment of Parkinson's disease, its long-term use is associated with fluctuations in motor performance, abnormal movements and psychotic hallucinations. These late side-effects remain difficult to treat and thus raise questions as to the benefits and risks of first-time treatment with levodopa. Levodopa mainly alleviates akinesia and rigidity and to a lesser extent, tremor. Levodopa increases life expectancy. This paper reviews some recent developments in the pharmacology of Parkinson's disease. Recent findings indicate that not only central dopamine but also several other central neurotransmitter and receptor changes are involved in the pathophysiology of Parkinson's disease. New data on autonomic dysfunction in Parkinson's disease are presented. New methods of investigation (clinical rating scales, pharmacological tests, imaging techniques, etc.) are reviewed. Finally, future strategies, e.g. the development of potent new symptomatic drugs (selective D2 and D1 agonists, new formulations of apomorphine, COMT inhibitors, new routes of administration, etc.) and etiopathogenic agents (antioxidative and anti-free radical drugs, etc.) are discussed.
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PMID:Recent advances in the clinical pharmacology of Parkinson's disease. 168 24

Behavioural and some neurochemical effects of Ro 40-7592 (3,4-dihydroxy-4'-methyl-5-nitrobenzophenone), a new COMT inhibitor, were studied in rats and mice. Ro 40-7592 increased the effect of L-DOPA (plus benserazide) on locomotor activity, reserpine-induced hypothermia, and catalepsy induced by pimozide, haloperidol and fluphenazine. Locomotor hyperactivity induced by amphetamine or nomifensine, as well as stereotypy induced by amphetamine (but not apomorphine), were also increased by Ro 40-7592. The drug stimulated exploratory activity in the open field test. It decreased the levels of HVA and 3-MT, increased the level of DOPAC but did not change the levels of dopamine in the striatum, nucleus accumbens and frontal cortex. These results indicate that Ro 40-7592 may improve the therapy with L-DOPA (plus decarboxylase inhibitor) of Parkinson's disease.
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PMID:Behavioural and neurochemical effects of Ro 40-7592, a new COMT inhibitor with a potential therapeutic activity in Parkinson's disease. 197 8

A random biochemical screening followed by lead optimization culminated in the discovery of Ro 40-7592 3,4-dihydroxy-4'-methyl-5-nitrobenzophenone). Ro 40-7592 was found to inhibit COMT in a competitive fashion both in the CNS and in the periphery (Ki for the liver enzyme = 30 nM). Ro 40-7592 (30 mg/kg p.o.) combined with benserazide (15 mg/kg p.o.) and a low dose of L-DOPA (10 mg/kg p.o.) almost completely blocked (for about 6 h) the formation of 3-O-methyldopa (3-OMD) in brain and plasma, producing a long-lasting increase of L-DOPA in plasma and a parallel marked increase of L-DOPA and dopamine in the brain. Ro 40-7592, combined with peripheral decarboxylase inhibitors and L-DOPA (as in Madopar and Sinemet), will offer substantial advantages in the therapy of Parkinson's disease, i.e. enhanced bioavailability and prolonged plasma half-life of L-DOPA, pronounced DOPA sparing effect and blockade of 3-OMD formation.
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PMID:Ro 40-7592: inhibition of COMT in rat brain and extracerebral tissues. 208 2

The effects of a COMT-inhibitor, U-0521, and a MAO-B-inhibitor, 1-deprenyl, on L-dopa-induced circling behaviour were compared in 6-OHDA-lesioned rats. The actions of U-0521 and 1-deprenyl on the anti-cataleptic effect of L-dopa were also studied. Both U-0521 and 1-deprenyl were found to potentiate L-dopa-induced circling behaviour and anti-cataleptic effect of L-dopa. In both test systems the L-dopa potentiation of 1-deprenyl was longer-lasting than that caused by U-0521. Thus inhibition of COMT, like inhibition of MAO, is able to enhance the central effects of L-dopa. This principle might be beneficial in the treatment of Parkinson's disease especially if COMT-inhibitors with greater performance can be developed.
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PMID:Potentiation of central effects of L-dopa by an inhibitor of catechol-O-methyltransferase. 296 Jul 78

OMD inhibits L-DOPA utilization in rat corpus striatum. This effect is probably mediated through competition with L-DOPA for brain uptake mechanism. Such competition may explain the inhibition exerted by OMD on L-DOPA-induced rotation in rats with unilateral destruction of the nigrostriatal pathway. U-0521, a potent COMT inhibitor, was shown, after i.p. injection, to effectively block the accumulation of OMD in the plasma and to enhance L-DOPA metabolism in rat brain. This drug, however, was not active when given orally to rats and to a single patient with Parkinson's disease. It is suggested that the combined use of L-DOPA plus an orally active COMT inhibitor may be useful in future treatment of Parkinson's disease.
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PMID:Catechol-O-methyltransferase and Parkinson's disease. 669 93

The same bimodal distribution of erythrocyte catechol-O-methyltransferase (RBC-COMT) was found in normal Caucasians and Orientals, but the frequency distribution of high RBC-COMT activity of the Orientals was significantly greater than that of the Caucasians. There was no difference in RBC-COMT frequency distribution between Oriental ethnic groups studied (i.e., Chinese and Filipinos). Since Caucasians with Parkinson's disease who had high RBC-COMT activity appeared to have more adverse effects from levodopa (L-dopa) than had those with low RBC-COMT activity, L-dopa doses and adverse responses in Filipinos with parkinsonism were compared to those of Caucasians with parkinsonism. The Filipinos were prescribed substantially lower doses than were the Caucasian patients, and more Filipinos than Caucasians developed dyskinesia at comparable doses of L-dopa. The possible association of the clinical differences in L-dopa tolerance and response between Filipinos and Caucasians with Parkinson's disease, with the racial differences in RBC-COMT activity is discussed.
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PMID:Difference in erythrocyte catechol-O-methyltransferase activity between Orientals and Caucasians: difference in levodopa tolerance. 673 32

Catechol O-methyltransferase (COMT, EC 2.1.1.6) is important in the central nervous system because it metabolizes catecholamine neurotransmitters such as dopamine. The enzyme catalyses the transfer of the methyl group from S-adenosyl-L-methionine (AdoMet) to one hydroxyl group of catechols. COMT also inactivates catechol-type compounds such as L-DOPA. With selective inhibitors of COMT in combination with L-DOPA, a new principle has been realized in the therapy of Parkinson's disease. Here we solve the atomic structure of COMT to 2.0 A resolution, which provides new insights into the mechanism of the methyl transfer reaction. The co-enzyme-binding domain is strikingly similar to that of an AdoMet-dependent DNA methylase, indicating that all AdoMet methylases may have a common structure.
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PMID:Crystal structure of catechol O-methyltransferase. 812 73

In addition to impaired dopaminergic neurotransmission a dysfunctional noradrenergic system has been demonstrated in Parkinson's disease. L-threo-3,4-dihydroxyphenylserine (DOPS), a synthetic precursor of noradrenaline (NA), appears to be effective in the treatment of some akinetic symptoms in parkinsonian patients. In the present study the possible effect of DOPS was studied in rats, in which catalepsy was induced with haloperidol as a model for parkinsonian akinesia. Intravenous infusion of NA (1.5 and 15 micrograms/kg) or DOPS (2 and 4 mg/kg) in male Wistar rats (240-290 g) significantly decreased catalepsy. The effect of DOPS was abolished by pretreatment with the peripheral decarboxylase inhibitor benserazide (2 mg/kg). Pretreatment with Ro 40-7592, a catechol-O-methyltransferase inhibitor, potentiated and prolonged the anticataleptic effect of DOPS. The findings suggest a peripheral site of NA mediated anticataleptic action. Therapy with DOPS may be successful only without a peripheral decarboxylase inhibitor. Moreover, the therapeutic effect of DOPS may be potentiated by COMT inhibition.
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PMID:Attenuation of haloperidol-induced catalepsy by noradrenaline and L-threo-DOPS. 821 60

Neurotrophic factors, like e.g. nerve growth factor (NGF), neurotrophin 3 (NT-3) or brain-derived neurotrophic factor (BDNF) promote the survival and function of neurones in the peripheral and central nervous system. Dopamine or other biogenic amines induce the biosynthesis of neurotrophic factors in glial and neuronal cells. Therefore inhibition of enzymes, like the extraneuronal and neuronal located MAO or the predominantly glial situated COMT, which both metabolize catecholamines, may induce an increased biosynthesis of neurotrophic factors. Due to clinical studies especially MAO-B-inhibitors appear to slow the progression of neurological deficits in Parkinson's disease and the cognitive decline in Alzheimer's disease. On the one hand inhibition of COMT alone may also slow the metabolisation of biogenic amines in glial cells and may consequently induce synthesis of neurotrophic factors in glial cells. But on the other hand in vivo and in vitro studies show, that COMT-inhibitors may intensify the metabolisation of catecholamines in neurones by MAO, what may cause an enhanced generation of free radicals. This increase of free radicals may induce lipid peroxidation of membranes and therefore cause accelerated neuronal and glial cell death. For that reason we conclude, that centrally active COMT-inhibitors may only be used together with MAO-inhibitors in the neuroprotective treatment of neurodegenerative disorders. Medical treatment with both inhibitors will have to be performed very carefully due to cytotoxic effects of high catecholamine levels on neuronal and glial cells and due to possible prolongation or potentiation of the activity of several noradrenergic drugs in the periphery.
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PMID:Therapy with central active catechol-O-methyltransferase (COMT)-inhibitors: is addition of monoamine oxidase (MAO)-inhibitors necessary to slow progress of neurodegenerative disorders? 836 8


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