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At least 829 records · Page 46Linked to original sources
PubMed1988

Platelet monoamine oxidase B activity in women with premenstrual syndrome.

Several lines of evidence suggest a strong association between premenstrual syndrome and affective disorder. Similar psychological symptoms, behavioral manifestations, and biochemical etiologies have been reported. We attempted to evaluate the biologic interconnection between premenstrual syndrome and psychiatric disorder by investigating the platelet enzyme, monoamine oxidase B. The activity of this enzyme has been noted to be decreased in affective disorder, alcoholism, and psychiatric vulnerability. Platelet monoamine oxidase B activity, estradiol, and progesterone were assessed throughout one menstrual cycle in 13 women with premenstrual syndrome and 19 control subjects. No significant differences were noted between groups using these parameters. The study indicates that well-screened subjects with premenstrual syndrome are, as evidenced by the parameter of monoamine oxidase B, biochemically similar to normal control subjects.

Adolescent↗
PubMed1984

[Plea for monoamine oxidase inhibitors. Retrospective study of 350 cases].

The case-records of 350 outpatients treated with monoamine oxidase inhibitors have been reviewed. All patients presented with depression, obsessions or phobias. About two-thirds benefited from the drugs, particularly after other treatments (including psychotropic drugs, seismotherapy, psychotherapy and internment) had failed. With the moderate doses administered (iproniazide: 50 mg/day; nialamide: 100 mg/day) side-effects were uncommon and mild and no incident was noted in 32 general anaesthesias given for surgical operations. These findings should help in lifting the ban on this category of drugs. Monoamine oxidase inhibitors are effective, useful and sometimes indispensable after failure of other antidepressants.

Adult↗
PubMed1971

The kinetics of phenethylhydrazine oxidation by monoamine oxidase.

1. In the presence of the substrate benzylamine, phenethylhydrazine has been shown to be a competitive inhibitor of monoamine oxidase from rat liver and pig brain. 2. Phenethylhydrazine is also a substrate for monoamine oxidase. Reciprocal plots for hydrazine oxidation give families of intersecting lines in contrast with the parallel lines previously reported for tyramine oxidation. 3. Two possible modifications of the mechanism obeyed by tyramine oxidation are suggested, but the product inhibition results are insufficient to distinguish between these two mechanisms.

Amines↗
PubMed1976

Platelet monoamine oxidase activity in schizophrenia.

The activity of platelet monoamine oxidase in 12 chronic schizophrenic patients was not significantly different from that in a matched group of normal individuals. The authors emphasize the importance of simultaneous processing of control and patient blood samples and the use of carefully controlled techniques, since relatively minor changes in procedure can markedly influence platelet yield and leucocyte contamination.

Adult↗
PubMed1997

Does isatin interact with rat brain monoamine oxidases in vivo?

Isatin is a reversible endogenous monoamine oxidase (MAO) inhibitor found in the brain. The influence of isatin on the degree of irreversible MAO inhibition by phenelzine and pargyline has been studied in vitro and in vivo experiments. In vitro 10 and 100 microM isatin reduced irreversible inhibition of MAO A and MAO B assayed after mitochondria wash. Pretreatment of rats with 'anxiogenic dose' of isatin (10 mg/kg) protected neither MAO A nor MAO B against subsequently administered phenelzine (10 mg/kg). 'Anticonvulsant' dose of isatin (80 mg/kg) reduced phenelzine-dependent inhibition of MAO B but not MAO A. Data obtained suggest that the anticonvulsant effect of isatin does not result from the inhibition of MAO A and the increase of monoamine level in the brain reported in few laboratories is apparently stipulated by a mechanism that does not involve MAO A inhibition.

Animals↗
PubMed1976

Critical evaluation of measurement of platelet monoamine oxidase in man.

Some biochemical characteristics such as substrate specificity, substrate affinity and inhibitor sensitivity of monoamine oxidase of human blood platelets were investigated. Tyramine, tryptamine and beta-phenylethylamine were used as substrates. The apparent Michaelis constants, maximal velocity rates and I50 for the inhibitor tranylcypromine were determined. The data were analyzed according to Lineweaver-Burk and Dixon. The influence of amitriptyline, a prototype of tricyclic antidepressants, on the selected variables (Km, V, I50), was studied. The parameters investigated showed remarkably low interindividual differences when healthy volunteers were tested. The inhibitor activity of amitriptyline towards platelet monoamine oxidase depends on the substrate used. Amitriptyline concentrations which showed a pronounced effect on the enzyme characteristics are significantly higher than plasma levels of the drug found under therapeutic conditions.

Adult↗
PubMed1970

The role of monoamine oxidase in the response of the isolated central artery of the rabbit ear to tyramine.

1. Monoamine oxidase activity was demonstrated histochemically throughout the media of the rabbit ear artery but not in the adventitia at its border with the media where the sympathetic nerve terminals are concentrated. Neither intensity nor distribution of enzyme activity was perceptibly altered up to 60 days after sympathetic denervation.2. Iproniazid and nialamide increased the sensitivity of the artery to intraluminal tyramine much more than that to extraluminal tyramine, so that the difference between the potencies for the two routes of administration became less marked.3. The results indicate that inactivation by monoamine oxidase in the media is a factor contributing to the relatively low potency of intraluminal tyramine on the artery.

Animals↗
PubMed1978

Monoamine oxidase activity in tissues of spontaneously hypertensive rats.

Monoamine oxidase (MAO) activity was assayed both in central and peripheral blood vessels of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar Kyoto rats (WKR). The activity of MAO in the brain and peripheral vasculature was essentially the same in both SHR and WKR. It can therefore be concluded that central and peripheral vascular MAO activity is not altered in the genetically hypertensive animals.

Animals↗
PubMed1977

Effect of hyper- and hypothyroidism on platelet monoamine oxidase activity and serotonin metabolism.

We evaluated platelet monoamine oxidase (MAO) activity in 13 hyperthyroid and 9 hypothyroid patients. The platelet MAO activity of these patients did not differ from that of age- and sex-matched euthyroid control subjects. Nineteen hyperthyroid and twelve hypothyroid subjects had serum serotonin concentrations similar to those of age- and sex-matched euthyroid control subjects. We also determined the urinary excretion of 5-hydroxy-indoleacetic acid (5-HlAA), serotonin, tryptamine, and tyramine in five hyperthyroid and four hypothyroid subjects. Two hyperthyroid patients had increased tyramine excretion; one of these patients also had increased tryptamine excretion. Three hypothyroid patients and one hyperthyroid patients had slightly decreased serotonin excretion. Both the hyper- and the hypothyroid subjects had normal urinary 5-HIAA excretion. There was no relationship between platelet MAO activity and monoamine excretion in the patients with thyroid dysfunction. We conclude that there is no systematic change in platelet MAO activity or serum serotonin concentration in patients with hyper- or hypothyroidism.

Adult↗
PubMed1995

Evidence for a genetic association between alleles of monoamine oxidase A gene and bipolar affective disorder.

We present evidence of a genetic association between bipolar disorder and alleles at 3 monoamine oxidase A (MAOA) markers, but not with alleles of a monoamine oxidase B (MAOB) polymorphism. The 3 MAOA markers, including one associated with low MAOA activity, show strong allelic association with each other but surprisingly not with MAOB. Our results are significant only for females, though the number of males in our sample is too small to draw any definite conclusions. Our data is consistent with recent reports of reduced MAOA activity in patients with abnormal behavioral phenotypes. The strength of the association is weak, but significant, which suggests that alleles at the MAOA locus contribute to susceptibility to bipolar disorder rather than being a major determinant.

Alleles↗
PubMedDate not supplied

[The role of monoamine oxidase in large intestine pathology].

The activity of monoamine oxidase (MAO) was studied during functional, inflammatory and tumoral diseases of the large intestine. In the patients with the irritable colon syndrome, the enzymatic activity was decreased by 34% at the acute stage of the disease and in those with nonspecific ulcerative colitis it was increased by 44%. Follow-ups of MAO activity may serve as an indicator of the adequacy and efficiency of the treatment performed.

Adult↗
PubMed1982

Inhibition of rat liver monoamine oxidase by alpha-methyl- and N-propargyl-amine derivatives.

The inhibition of rat liver monoamine oxidase by a number of N-propargyl and alpha-methyl amine derivatives has been examined. The results indicate that alpha-methyl-substituted primary and secondary amine derivatives tend to show selectivity as reversible inhibitors towards the A-form of the enzyme. The structural features that result in selectivity in irreversible inhibitors are less easy to define and substitution of an N-propargyl group into a compound that is a selective reversible inhibitor of monoamine oxidase will not necessarily result in retention of that selectivity. Replacement of the acetylenic group in a B-selective irreversible inhibitor by an ethylenic group resulted in a compound that was a reversible inhibitor showing slight selectivity for the A-form of the enzyme.

Alkynes↗
PubMed1985

Serotonin depression of local cerebral glucose utilisation after monoamine oxidase inhibition.

The major catabolic enzyme for serotonin, monoamine oxidase (MAO), is present in the endothelium of cerebral vessels. We report the effects of the intracarotid administration of serotonin on local cerebral glucose utilisation in rats following MAO inhibition with the drug clorgyline. It was found that saline, clorgyline, or serotonin alone produced no significant changes in glucose utilisation. Following the infusion of clorgyline, the administration of serotonin produced significant decreases in glucose utilisation in cortical areas of between 12 and 33% and in the caudate nucleus of 16%.

Animals↗
PubMedDate not supplied

Thyroxine and propylthiouracil-induced changes in the activity of monoamine oxidase in the fetal rat.

The activity of monoamine oxidase (MAO) towards tryptamine has been determined in heart, brain and liver of the 21.5 day old rat fetus. The activity was compared between normal, thyroxine and propylthiouracil (PTU) treated animals. Hypothyroidism induced by PTU leads to a decrease in the activity of the three organs, while hyperthyroidism causes an increase in the enzymatic activity. These differences seem to be rather independent of the protein content of the organs. It appears thar rat fetal MAO is under a strong thyroid control.

Animals↗
PubMed1984

Platelet monoamine oxidase activity and genetic vulnerability to schizophrenia.

Platelet monoamine oxidase (MAO) activity, determined in 102 patients with chronic schizophrenia, 223 first-degree relatives, and 88 normal control subjects, was shown to be a heritable and stable trait and was significantly lower in patients than in normal control subjects. Within families, MAO activity distinguished ill from well relatives. However, the considerable overlap in enzyme activity between affected and unaffected individuals limits the usefulness of low MAO activity as a major risk factor in schizophrenia.

Adolescent↗
PubMed1980

Personality correlates of platelet monoamine oxidase activity anbd red cell lithium transport.

Platelet monoamine oxidase (MAO) activity and the ratio of red cell to plasma lithium concentrations (Li ratio) may be important in the pathophysiology of, and genetic vulnerability to, some psychiatric disorders. By using the Clinical Analysis Questionnaire, we assessed personality correlates of MAO activity and the Li ratio in vitro in a sample of psychiatrically normal adult women. We found that there were correlates of each variable, and a unique constellation of personality traits when the two variables were considered simultaneously.

Adolescent↗
PubMed1993

A subpopulation of mouse striatal cholinergic neurons show monoamine oxidase activity.

We examined the histochemical localization of monoamine oxidase (MAO) in the mouse striatum. MAO activity was observed in glial cells and vessels in accordance with previous reports in the rat brain. In addition to these previously documented structures, we found MAO-containing neurons in the mouse striatum. Enzyme inhibition experiments showed that MAO in the positive neurons was predominantly of type B. Double-labeling studies showed that in this region these neurons were cholinergic. The functional role of MAO activity in the mouse striatal cholinergic neurons is presently unclear.

Acetylcholinesterase↗