Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of rat brain synaptosomes and mitochondria with LPO inducers (Fe2+ and ascorbate) was accompanied by a decrease of deamination of serotonin (substrate of MAO-A) in mitochondria, but not in synaptosomes, with simultaneous stimulation of GABA and GLCA deamination, apparently owing to modification of catalytic properties of brain membrane-bound MAO. Oxidation of PEA (substrate of MAO-B) was insignificantly altered in both fractions. Reactions of deamination of serotonin, GABA, and GLCA (but not PEA), were highly sensitive to a selective inhibitor of MAO-A pyrazidol (pyrlindole). Isoniazid and hydrazides of quinoline carbonic acids (inhibitors of both modified MAO and copper-containing amine oxidases) strongly inhibited deamination of GABA and GLCA. During epileptiformic seizures in rats, genetically selected for high incidence of audiogenic epilepsia, stimulation in brain synaptosomes and mitochondria of LPO was observed. This was accompanied by a marked decrease in serotonin and PEA deamination, with a simultaneous increase in GABA and GLCA deamination in both fractions. The data obtained suggest that appearance of GABA-deaminating activity owing to modification of catalytic properties of MAO, might be an essential pathogenetic component in the development of epileptic seizures.
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PMID:The role of lipid peroxidation in the possible involvement of membrane-bound monoamine oxidases in gamma-aminobutyric acid and glucosamine deamination in rat brain. Focus on chemical pathogenesis of experimental audiogenic epilepsy. 152 Apr 3

Identification, cellular localization, and cDNA cloning of MAO subtypes A and B have increased the insight into the pharmacology of these enzymes, whose primary functions are intra- and extraneuronal inactivation of neurotransmitter (dopamine, noradrenaline and serotonin) and other biogenic amines. In addition, MAO oxidizes the inert uncharacteristic tertiary amine, MPTP, to the parkinson inducing dopaminergic neurotoxin, MPP+, and the novel secondary amine anticonvulsant milacemide to the inhibitory amino acid neurotransmitter, glycine. These recent developments have provided new therapeutic perspectives for the management of Parkinson's disease and seizure disorders via the use of selective inhibitors and amino acid amine prodrug substrates of MAO-B.
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PMID:New directions in monoamine oxidase A and B selective inhibitors and substrates. 198 26

The novel glycine-prodrug anticonvulsant, milacemide (2-N-pentylaminoacetamide) (500 mg/kg), significantly increased (greater than 400% the seizure threshold induced by hyperbaric oxygen (4.5 atmosphere). This effect was significantly reduced by the selective inhibition of monoamine oxidase B by 1-deprenyl (2.0 mg/kg). 1-Deprenyl alone hardly affected the seizure threshold. These results suggest that, in the brain, milacemide is oxidized to glycine and that this reaction is mediated primarily by monoamine oxidase B. However, the interaction of milacemide metabolites (glycine amide, pentanoate and glycine) as antagonists of receptors of the glutamate NMDA (N-methyl-D-aspartate) subtype cannot be excluded.
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PMID:The glycine-prodrug, milacemide, increases the seizure threshold due to hyperbaric oxygen; prevention by 1-deprenyl. 313 41

We previously reported that 6-methoxy-1,2,3,4-tetrahydro-beta-carboline (6-MeO-THBC) attenuated audiogenic seizures (AGS) in 21-day-old DBA/2J mice and also inhibited brain monoamine oxidase-A (MAO-A) and serotonin (5-hydroxytryptamine, 5-HT) uptake leading to increased brain 5-HT concentration. In this study, the sensitivity of AGS to 5-HT manipulation was evaluated by utilizing drug combinations which paralleled the actions of 6-MeO-THBC and which also have been associated with the production of a serotonergic motor syndrome in rats. Combination of a specific 5-HT uptake inhibitor (fluoxetine or citalopram) with the MAO-A inhibitor clorgyline inhibited AGS more effectively than the individual drugs but combination with the MAO-B inhibitor deprenyl did not. Combined administration of clorgyline plus deprenyl also suppressed AGS. Inhibition of AGS by tryptophan was potentiated by combination with either of the mixed MAO inhibitors nialamide or tranylcypromine. The effects of these drugs individually and in combination on brain MAO-A and MAO-B activity and 5-HT uptake were also determined ex vivo and were consistent with expected mechanisms of action. These results suggest, first of all, that the inhibition of AGS produced by 6-MeO-THBC is a consequence of its combined MAO-A and 5-HT uptake inhibition properties. Secondly, the similarity of results of pharmacological manipulations of the 5-HT system which produce the rat motor syndrome and which inhibit AGS in the mouse suggests that AGS in 21-day-old DBA/2J mice may be a useful system for assessing functional consequences of these serotonergic manipulations.
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PMID:Combined inhibition of serotonin uptake and oxidative deamination attenuates audiogenic seizures in DBA/2J mice. 408 Jul 61

The relationship between deprenyl (MAO-B inhibitor), beta-phenylethylamine (PEA, MAO-B substrate) and [D-Ala2]-Met-enkephalinamide (DALA)-induced seizure was studied in the urethane-anaesthetized rats. A combined electromyographic (EMG) and electrocorticographic (ECoG) method was used. PEA (20-100 micrograms ivt) or DALA (10 micrograms ivt) induced myoclonic contractions (MC) in the submandibular muscle and epileptiform pattern with spike activity in the ECoG. Administration of subconvulsant doses of PEA (5-10 micrograms ivt 0.5-1 min before DALA) significantly increased DALA-induced seizure activity. Similarly, blockade of MAO-B with deprenyl (3-48 mg/kg ip) also enhanced DALA-induced epileptiform pattern. It is evident from this study that MAO-B system significantly modulates the excitatory phenomena induced by DALA. These findings of interactions between MAO-B system and enkephalinergic one, might be of relevance in the clinical situations such as psychosis, stress, a use of tricyclic antidepressants and all other cases, where the alteration of MAO-B system is a part of disease or induced during drug therapy.
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PMID:MAO-B inhibitor deprenyl and beta-phenylethylamine potentiate [D-ALA2]-Met-enkephalinamide-induced seizures. 640 86

Monoamine neurotransmitters are important in the development of the immature mammalian brain, prior to assuming their role as neurotransmitters. The endogenous levels of these transmitters are highly regulated by the enzyme monoamine oxidase (MAO). Thus, any change in this enzyme should have a profound effect on brain development. In order to test this hypothesis, we treated developing rat pups with the monoamine oxidase inhibitors (MAO-Is), clorgyline (MAO-A, 3 mg/kg), and deprenyl (MAO-B, 3 mg/kg) throughout gestation (MAO-I-birth), or throughout gestation and to sacrifice (MAO-I-sac). The animals were analyzed for serotonin and dopamine terminal density, using 3H-paroxetine and 3H-GBR 12935, respectively. Whereas there were no changes in the development of the dopamine system, the serotonin system was severely affected, particularly in the cortex that showed a significant reduction of innervation at 30 days postnatal. The animals reached all normal development milestones on schedule, and had no changes in measures of anxiety (% light/dark); however, the animals showed increased open field activity and deficits in a passive avoidance paradigm, which may be a measure of impulsivity. The MAO-I-sac animals were severely impaired, showing stereotypic behavior, seizures, and eventually visual impairments. Our results are discussed in terms of relevance to human disease states, such as atypical Norrie's disease, impulsivity, and hyperactivity. As well, our results should be used to caution against the use of MAO-Is in women of child-bearing age.
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PMID:Effects of gestational exposure to monoamine oxidase inhibitors in rats: preliminary behavioral and neurochemical studies. 784 Aug 64

Norrie disease (ND) is an X-linked recessive disorder causing ocular atrophy, mental retardation, deafness, and dysmorphic features. Virtually absent monoamine oxidase (MAO) type-A and -B activity has been found in some boys with chromosome deletions. We report the coexistence of cataplexy and abnormal REM sleep organization with ND. Three related boys, referred for treatment of medically refractory atonic spells and apneas, underwent extended EEG-video-polysomnographic monitoring. They demonstrated attacks of cataplexy and inappropriate periods of REM sleep during which they were unarousable. One boy also had generalized tonic-clonic seizures. Previous testing revealed that all three have complete ND gene deletions. In all subjects, platelet MAO-B activity was absent, serum serotonin levels were markedly increased, and plasma catecholamine levels were normal. Data from the canine narcolepsy syndrome model implicate abnormal catecholaminergic and cholinergic activities in the pathogenesis of cataplexy. Our findings suggest that abnormal MAO activity or an imbalance between serotonin and other neurotransmitter levels may be involved in the pathogenesis of human cataplexy.
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PMID:Cataplexy and monoamine oxidase deficiency in Norrie disease. 862 63

Several PET receptor ligands have been used to investigate the neurochemical basis of the epilepsies. 11C-Flumazenil binds to the central benzodiazepine receptor (cBZR)-gamma-aminobutyric acid (GABA) A receptor complex; 11C-diprenorphine, 18F-cyclofoxy, and 11C-carfentanil to opiate receptors; and 11C-Deprenyl to monoamine oxidase B. These studies should be considered alongside high-quality magnetic resonance imaging that demonstrates the structural basis of the condition. The results should be correlated with those of quantitative in vitro neuropathologic and autoradiographic studies. Idiopathic generalized epilepsy has been studied with 11C-flumazenil and 11C-diprenorphine. There is no evidence of any interictal overall abnormality of opioid receptors in idiopathic generalized epilepsy, but typical absences have been found to displace 11C-diprenorphine from the association areas of the neocortex. This finding implies that release of endogenous opioids has a role in the pathophysiologic mechanisms of typical absences in humans. In contrast, binding of 11C-flumazenil to cBZRs has been shown not to be affected by serial absences. Studies of interictal 11C-flumazenil binding in idiopathic generalized epilepsy have not given uniform results. In one investigation a slight reduction was reported in the neocortex of patients with idiopathic generalized epilepsy in comparison with patients with partial seizures. Also observed was increased benzodiazepine receptor density in the cerebellar nuclei and decreased density in the thalamus. Widespread increases in cBZRs also have been reported in cerebral neocortex, thalamus, and cerebellar cortex. In unilateral hippocampal sclerosis, reduction of binding of 11C-flumazenil has been shown to be confined to the hippocampus and to be over and above that caused by neuron loss and hippocampal atrophy. In malformations of cortical development, abnormalities of cBZRs, as demonstrated with 11C-flumazenil PET, are more extensive than the structural abnormality revealed with magnetic resonance imaging. There often are areas of increased cBZRs, a pattern that appears unique to malformations of cortical development and that may reflect both functional and structural anomalies. In patients with mesial temporal lobe epilepsy, upregulation of mu opioid receptors has been found in lateral neocortex without an overall increase of opioid receptor binding. The pathophysiologic explanation for this finding is not clear. Possibilities include up-regulation of mu receptors in response to epileptic activity and down-regulation or occupation of kappa opioid receptors. Important future developments in this field that will increase understanding of the processes that underlie the epilepsies will come from the development of further ligands, particularly tracers that are specific for excitatory amino acid receptors, the subtypes of the opioid receptors, and the GABAB receptor.
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PMID:Positron emission tomography receptor studies. 1051 72

OBJECTIVE: Positron emission tomography (PET) studies in patients with temporal lobe epilepsy have reported that hypometabolism in temporal regions is associated with elevated monoamine oxidase B (MAO B) probably reflecting gliosis. The purpose of this study was to examine a group of head trauma patients suffering from seizures and memory loss to determine whether hypometabolic regions show correspondingly elevated MAO B.METHODS: Seven patients with traumatic brain injury received PET scans with (18)FDG and [(11)C]L-deprenyl-D2 to measure regional glucose metabolism (LCMRglu) and MAO B respectively. Results were compared to a group of nine age-matched healthy controls. Hypometabolic regions were identified and MAO B values corresponding to these brain regions were determined. Averaged brain images for temporal regions for LCMRglu and MAO were also compared.RESULTS: LCMRglu values for temporal regions were reduced in patients relative to normal subjects. Of the 13 hypometabolic brain regions, 6 (46%) showed a corresponding elevation in MAO B. There was a trend for a significant inverse relationship between normalized LCMRglu and normalized MAO B values for medial temporal cortex. Glucose metabolism was significantly higher in lateral than medial temporal regions whereas the pattern was reversed for MAO B.CONCLUSION: MAO B images provide a markedly better delineation of the medial temporal regions than LCMRglu. There was not a consistent inverse relationship between metabolism and MAO B as had been reported in PET studies of epileptogenic temporal lobes with [(11)C]L-deprenyl-D2 and (18)FDG indicating that prospective studies are needed to determine the pathophysiology of hypometabolic lesions in head trauma.
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PMID:Comparison of Brain Glucose Metabolism and Monoamine Oxidase B (MAO B) in Traumatic Brain Injury. 1451 43

TCH-346, an anti-apoptotic compound, is under development by Novartis for the potential treatment of Parkinson's disease (PD) and motor neuron disease [271447,342937]. By September 1999, phase I clinical trials for PD were underway [342937]. The compound was discovered in a screen for molecules with both norepinephrine uptake and MAO inhibiting properties but, although it had anti-apoptotic properties, it did not inhibit MAOA or MAO-B [333136,332004]. The compound increases lifespan in the progressive motorneuropathy mouse model and prevents ischemia in models of ischemia and seizure [288893]. In vivo, it shows neurorescuing and anti-apoptotic properties in PC12 cells and cerebellar granule cells, among others, at concentrations of 0.1 pM to 10 microM, suggesting that its action might prove potentially useful against Alzheimer's and/or Parkinson's disease [332004]. The compound has also shown neurorescuing properties in rat pups after axotomy, rat hippocampal CA1 neurons after transient ischemia/hypoxia and mouse nigral dopaminergic (DA) neurons after treatment with MPTP in doses ranging between 0.0003 and 0.1 mg/kg po or sc, depending on the model [333136]. Data presented by the University of Nijmengen and the Free University of Amsterdam show that TCH-346 improves the behavioral and enzymatic outcome in the rat 6-OH-dopamine model of Parkinson's disease. TCH-346 (0.0014 mg/kg sc bid) prevented abnormal stepping (open field test) and prevented increases in fore and hind-paw retraction time. TCH-346 also improved acquisition in the Morris water maze task and, at doses between 0.0014 and 0.14 mg/kg, prevented reduction in tyrosine hydroxylase immunoreactivity [345259]. Affinity binding studies with TCH-346 showed that GAPDH is the target [294902,283200]. Differential display RT-PCR also showed that protein-isoaspartyl-methyl transferase is induced by the drug [283200].
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PMID:TCH-346 (Novartis). 1610 Jun 86


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