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Results for “MONOAMINE OXIDASE”

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PubMed2006

Serotonin transporter, tryptophan hydroxylase, and monoamine oxidase A gene polymorphisms in premenstrual dysphoric disorder.

OBJECTIVE: The purpose of this study was to investigate whether common polymorphisms of key genes that control the serotonin (5-hydroxytryptamine) pathway are associated with premenstrual dysphoric disorder. STUDY DESIGN: The study sample comprised 53 women with clinically diagnosed premenstrual dysphoric disorder (age range, 27-46 years; mean age, 37.7 years) and 52 healthy control subjects (age range, 22-48 years; mean age, 36.2 years). Eight polymorphisms that encode the 5-hydroxytryptamine transporter (LPR, VNTR-2, and 3' UTR G/T), tryptophan hydroxylase 1 (TPH1 G-6526A, G-5806T, and A218C), and monoamine oxidase A (monoamine oxidase A promoter VNTR-1 and exon 8 Fnu 4H1) were genotyped. Genotype and allelic frequencies were analyzed by chi-square test and stepwise logistic regression analysis. RESULTS: There was no significant association between any genotype and clinical category and no significant allelic distribution profiles in either the premenstrual dysphoric disorder group or the control group. CONCLUSION: These findings do not support a major role for common 5-hydroxytryptamine transporter, TPH1, and monoamine oxidase A polymorphisms in contributing to susceptibility to premenstrual dysphoric disorder.

Adult↗

PubMed2004

A spontaneous point mutation produces monoamine oxidase A/B knock-out mice with greatly elevated monoamines and anxiety-like behavior.

A spontaneous monoamine oxidase A (MAO A) mutation (A863T) in exon 8 introduced a premature stop codon, which produced MAO A/B double knock-out (KO) mice in a MAO B KO mouse colony. This mutation caused a nonsense-mediated mRNA decay and resulted in the absence of MAO A transcript, protein, and catalytic activity and abrogates a DraI restriction site. The MAO A/B KO mice showed reduced body weight compared with wild type mice. Brain levels of serotonin, norepinephrine, dopamine, and phenylethylamine increased, and serotonin metabolite 5-hydroxyindoleacetic acid levels decreased, to a much greater degree than in either MAO A or B single KO mice. Observed chase/escape and anxiety-like behavior in the MAO A/B KO mice, different from MAO A or B single KO mice, suggest that varying monoamine levels result in both a unique biochemical and behavioral phenotype. These mice will be useful models for studying the molecular basis of disorders associated with abnormal monoamine neurotransmitters.

Amino Acid Sequence↗

PubMed1991

Central monoamine oxidase and phenolsulfotransferase activities in spontaneously hypertensive rats.

The activities of monoamine oxidase and phenolsulfotransferase in the hypothalamus and anterior pituitary gland of spontaneously hypertensive rats and the normotensive control (Wistar Kyoto rat) rats were investigated. The monoamine oxidase activity (determined using dopamine as substrate) in both these tissues was not significantly different between the normo- and hypertensive animals. Hypothalamic phenolsulfotransferase does not sulfate-conjugate dopamine at pH of 6.5 and pituitary phenolsulfotransferase does not sulfate-conjugate dopamine or 3,4-dihydroxyphenylacetic acid at the same pH. Hypothalamic phenolsulfotransferase activity determined using 3,4-dihydroxyphenylacetic acid as substrate was significantly higher in the spontaneously hypertensive than the Wistar Kyoto rats, while pituitary enzyme (determined using phenol as substrate) was the same in both strains of animals. We proposed that in the spontaneously hypertensive rats the higher level of hypothalamic phenolsulfotransferase could (by removing 3,4-dihydroxyphenylacetic acid as sulfated acid) increase the deamination of dopamine by monoamine oxidase. This could in turn result in the presence of high amount of sulfated 3,4-dihydroxyphenylacetic acid in the anterior pituitary gland reported in our earlier study, and be partly responsible for the reduced central dopaminergic activity found in the hypertensive rats.

Animals↗

PubMed1984

Low platelet monoamine oxidase activity in headache: no correlation with phenolsulphotransferase, succinate dehydrogenase, platelet preparation method or smoking.

Platelet monoamine oxidase activity in male migrainous and cluster headache patients was significantly lower than in male controls, confirming our previous study. The activity range showed a normal distribution and low mean values could not be attributed to a subgroup with particularly low activity. When Corash 's platelet preparation method was used, with its high platelet yield, specific enzyme activities of a similar order were obtained. Thus, the low values encountered were not due to abnormal recovery within the platelet population. Two other enzyme activities, phenolsulphotransferase M and succinate dehydrogenase, were also measured in the same platelet samples. Although low succinate dehydrogenase activity was identified in the headache groups, it appeared to represent a separate phenomenon and there was no significant correlation between activity of either enzyme and that of monoamine oxidase. This shows that the low activity of platelet monoamine oxidase in headache is not related to a generalised platelet enzyme deficit. It was also shown that the low monoamine oxidase activity in the headache patients could not be attributed to smoking.

Arylsulfotransferase↗

PubMed1998

Transcription factor binding to the core promoter of the human monoamine oxidase B gene in the cerebral cortex and in blood cells.

Many studies show that monoamine oxidase B in blood cells is a biological marker for personality characteristics such as sensation seeking. The mechanism underlying this association is so far not explored. In the present study we have performed electrophoretic mobility-shift assays to investigate the pattern of protein binding to a 150 bp fragment of the proximal 5'-flanking region of the human monoamine oxidase B gene. We compared the pattern using nuclear extracts from human brain and lymphocytes. Interestingly, a correlation was observed between monoamine oxidase B enzyme activity in blood cells (platelets) and the binding pattern of two uncharacterized transcription factors. These data are well in line with the long-standing notion that interindividual differences in platelet monoamine oxidase may represent differences in expression of the enzyme rather than genotypic variation.

Blood Platelets↗

PubMed1993

Effect of ethanol and progesterone on monoamine oxidase activity in cultured cells of human term placenta.

OBJECTIVE: The aim of this study was to evaluate the effect of ethanol and progesterone on the monoamine oxidase activity in cultured human term placental cells. STUDY DESIGN: Human placental cells were prepared from normal human term placentas by enzymatic dispersion in Dulbecco's modified Eagle medium. The viability of placental cells prepared by our method was 90%, and the yield of placental cells was 0.6 x 10(6) cells per gram of wet placental tissue. Five milliliters of Dulbecco's modified Eagle medium containing 3 x 10(5) placental cells was plated in a 25 cm2 flask and cultured for 8 days in an incubator at 37 degrees C under an atmosphere of 5% carbon dioxide and 95% oxygen with a saturated humidity. During the culture period the culture medium was replenished every 2 days. A confluent monolayer condition was achieved after 8 days in culture. The cultured placental cells were treated with different concentrations of ethanol (0, 34.6, and 69.2 mmol/L) and progesterone (0, 16, and 32 mumol/L) on day 8 of culture for 48 hours. At the end of treatment placental cells from control and treated flasks were harvested for the analysis of monoamine oxidase activity by spectrophotometry. The effects of ethanol and progesterone on cultured placental cells were statistically analyzed by one-way analysis of variance followed by Duncan's multiple comparisons procedure. RESULTS: A human placental cell culture system has been established from normal human term placentas. The monoamine oxidase activity in 8-day-cultured human term placental cells was significantly higher than that of freshly prepared placental cells. Ethanol concentrations at 34.6 and 69.2 mmol/L significantly increased and progesterone concentration at 32 mumol/L significantly decreased the monoamine oxidase activity. CONCLUSION: These results suggest that the cultured human term placental cells can be used to examine the in vitro effects of ethanol and progesterone on monoamine oxidase activity. However, the physiologic significance of progesterone's inhibitory effect and the stimulatory effect of ethanol monoamine oxidase activity in the in vivo system have yet to be further investigated.

Cells, Cultured↗

PubMed1979

Monoamine oxidase inhibition and recovery in the mouse brain at various ages after birth.

Mice between the ages of 1 day postpartum and adulthood were exposed to the monoamine oxidase inhibitors tranylcypromine and pargyline. The mice were killed at seven different times following drug injection and assayed in vitro for monoamine oxidase activity in four brain regions. Inhibition and recovery of monoamine oxidase activity varied by age, and with the two inhibitors used. During the early maturational period, the potential for new monoamine oxidase synthesis was greater than normal maturational patterns of increase would suggest; and during later maturation either the proportions of various monoamine oxidase forms or their rates of synthesis are different.

Age Factors↗

PubMed1976

5-Hydroxytryptamine is a substrate for both species of monoamine oxidase in beef heart mitochondria.

The activity of beef heart mitochondrial monoamine oxidase towards 5-hydroxytryptamine (5-HT) is inhibited by the selective inhibitors clorgyline, PCO [5-phenyl-3-(N-cyclopropyl)-ethylamine-1,2,4-oxidiazole] and Deprenyl with a biphasic dependence on the inhibitor concentration. The activities towards tyramine, dopamine and tryptamine were also inhibited in a biphasic manner, but the apparent proportions of the two enzyme species active on dopamine and tryptamine depended on the inhibitor used. Phenethylamine oxidation was inhibited in a monophasic manner suggesting that only a single enzyme species was responsible for the oxidation of this substrate. The biphasic response of 5-HT oxidation to inhibition by clorgyline persisted when functionally competent mitochondria were used and was unaffected by the soluble amine oxidase inhibitors semicarbazine and aminoguanidine. These results indicate that the behaviour of the beef heart enzyme towards selective inhibitors is considerably different from that of any preparations previously studied and suggest that the classification of monoamine oxidase activites into A and B types may be only of limited usefulness.

Amines↗

PubMed1979

On preparative separation of brain mitochondrial monoamine oxidases.

A method was developed for solubilization from bovine brain stem mitochondrial fraction of monoamine oxidases deminating biogenic amines. Preparative separation of the monoamine oxidases, possessing different substrate specificities, was achieved by column chromatography on a biospecific adsorbent AH-Sepharose 4 B. The enzyme preparations thus obtained did not contain any detectable by disc-electrophoresis of isoelectrofocusing in polyacrylamide gels proteins which were devoid of the monoamine oxidase activity.

Animals↗

PubMed1981

Effects of hycanthone and praziquantel on monoamine oxidase and cholinesterases in Schistosoma mansoni.

The effects of hycanthone and praziquantel on the activities of monoamine oxidases and cholinesterases were studied in the 600-g supernatant from homogenates of Schistosoma mansoni and mouse liver or brain. Hycanthone was shown to be a very potent inhibitor of monoamine oxidases from worms and mouse liver. Hycanthone also inhibited the specific and nonspecific cholinesterases of S. mansoni, but cholinesterase from mouse brain was not affected significantly by this drug. Praziquantel showed no effect on monoamine oxidase from mouse liver or the parasite; however, it was slightly inhibitory to S. mansoni cholinesterases at very high concentrations. Mouse brain cholinesterase required an even higher concentration of praziquantel to observe inhibition. The inhibition of monoamine oxidase in S. mansoni by hycanthone adds a new mode of action to our knowledge of this compound, and suggests another possibility for the development of future anthelminthics.

Animals↗

PubMed2006

Elevated monoamine oxidase a levels in the brain: an explanation for the monoamine imbalance of major depression.

CONTEXT: The monoamine theory of depression proposes that monoamine levels are lowered, but there is no explanation for how monoamine loss occurs. Monoamine oxidase A (MAO-A) is an enzyme that metabolizes monoamines, such as serotonin, norepinephrine, and dopamine. OBJECTIVE: To determine whether MAO-A levels in the brain are elevated during untreated depression. SETTING: Tertiary care psychiatric hospital. PATIENTS: Seventeen healthy and 17 depressed individuals with major depressive disorder that met entry criteria were recruited from the care of general practitioners and psychiatrists. All study participants were otherwise healthy and nonsmoking. Depressed individuals had been medication free for at least 5 months. MAIN OUTCOME MEASURE: Harmine labeled with carbon 11, a radioligand selective for MAO-A and positron emission tomography, was used to measure MAO-A DVS (specific distribution volume), an index of MAO-A density, in different brain regions (prefrontal cortex, anterior cingulate cortex, posterior cingulate cortex, caudate, putamen, thalamus, anterior temporal cortex, midbrain, hippocampus, and parahippocampus). RESULTS: The MAO-A DVS was highly significantly elevated in every brain region assessed (t test; P=.001 to 3x10(-7)). The MAO-A DVS was elevated on average by 34% (2 SDs) throughout the brain during major depression. CONCLUSIONS: The sizable magnitude of this finding and the absence of other compelling explanations for monoamine loss during major depressive episodes led to the conclusion that elevated MAO-A density is the primary monoamine-lowering process during major depression.

Adult↗

PubMed1999

Excess of high activity monoamine oxidase A gene promoter alleles in female patients with panic disorder.

A genetic contribution to the pathogenesis of panic disorder has been demonstrated by clinical genetic studies. Molecular genetic studies have focused on candidate genes suggested by the molecular mechanisms implied in the action of drugs utilized for therapy or in challenge tests. One class of drugs effective in the treatment of panic disorder is represented by monoamine oxidase A inhibitors. Therefore, the monoamine oxidase A gene on chromosome X is a prime candidate gene. In the present study we investigated a novel repeat polymorphism in the promoter of the monoamine oxidase A gene for association with panic disorder in two independent samples (German sample, n = 80; Italian sample, n = 129). Two alleles (3 and 4 repeats) were most common and constituted >97% of the observed alleles. Functional characterization in a luciferase assay demonstrated that the longer alleles (3a, 4 and 5) were more active than allele 3. Among females of both the German and the Italian samples of panic disorder patients (combined, n = 209) the longer alleles (3a, 4 and 5) were significantly more frequent than among females of the corresponding control samples (combined, n = 190, chi2 = 10.27, df = 1, P = 0.001). Together with the observation that inhibition of monoamine oxidase A is clinically effective in the treatment of panic disorder these findings suggest that increased monoamine oxidase A activity is a risk factor for panic disorder in female patients.

Alleles↗

PubMed2003

Six new constituents from an Ascomycete, Chaetomium quadrangulatum, found in a screening study focused on monoamine oxidase inhibitory activity.

A screening study focusing on monoamine oxidase inhibitory activity on the EtOAc extract of an Ascomycete Chaetomium quadrangulatum, which previously gave five unique chromones possessing this activity (chaetoquadrins A-E (1-5)), this time afforded six new constituents termed chaetoquadrins F-K (6-11) in addition to 1-5. The structures of 6-11 have been deduced on the basis of spectral and chemical data, and 7 and 8 have shown appreciable monoamine oxidase inhibitory activity.

Chaetomium↗

PubMedDate not supplied

[Monoamine oxidase and adenylate deaminase activity of mitochondrial fractions of the rat liver in alcoholic intoxication].

Decrease in monoamine oxidase and increase in diamine oxidase and adenylate deaminating activities were found in rat liver mitochondrial fractions after repeated injections of ethanol. A monoamine oxidase inhibitor pargyline and an inhibitor of phosphodiesterase theophylline prevented the increase in adenylate deaminating activity in a subfraction of mitochondrial membranes in the ethanol intoxicated rats. In a subfraction of soluble mitochondrial proteins pargyline did not affect but theophylline prevented completely the increase in adenylate deaminating activity. The stimulation of adenylate deaminating activity in mitochondrial fractions of rat liver in ethanol intoxication might be caused by: 1) transformation of mitochondrial monoamine oxidases (in the subfraction of mitochondrial membranes) and 2) activation (or increased biosynthesis) of the adenylate deaminase in the subfraction of soluble mitochondrial proteins. The adenylate cyclase system is probably involved in the latter process.

AMP Deaminase↗

PubMed1984

Histochemical localization of monoamine oxidase in whole-body, freeze-dried sections of mice.

Monoamine oxidase was investigated histochemically in tissues of the mouse by incubating freeze-dried, whole-body sections with tryptamine, serotonin, tyramine, beta-phenylethylamine, or benzylamine as substrate and Nitroblue tetrazolium as the final electron acceptor. The most intense staining with tryptamine was exhibited by intestinal epithelium and adrenal cortex; moderate staining was noted in the epithelium of the nose, bronchi, oesophagus, and upper stomach and in preputial gland, pancreas, nerve, spinal cord and brain. Weak staining was seen in the lung, spleen, liver and kidney. The distribution of the formazan deposition was similar, but much less intense, when serotonin and tyramine were used as the substrates. Only very weak staining was observed when beta-phenylethylamine was the substrate; no staining was seen with benzylamine. Monoamine oxidase activities with tryptamine were greatly inhibited by pretreatment with clorgyline (10 microM), while deprenyl (10 microM) slightly inhibited activities in all tissues except liver. This staining technique should be useful in further studies on the identification of the multiple forms of monoamine oxidase in tissues of the mouse. Nicotine and nitrosonornicotine were not substrates in any of the tissues; consequently, this enzyme system does not appear to produce the proximal carcinogen from this nitrosamine.

Adrenal Cortex↗

PubMed1976

Monoamine oxidase inhibition and the induction of ponto-geniculo-occipital wave activity by reserpine in the cat.

Reserpine induces ponto-geniculo-occipital wave activity similar to that seen in the cat during the rapid eye movement phase of sleep. This action of reserpine was blocked by the monoamine oxidase inhibitors, pheniprazine, harmaline and clorgyline, but not deprenyl or its demethylated analog. After a single dose (20 mg/kg) of either pheniprazine or harmaline, the time course of antagonism of the effect of reserpine was in good correspondence with inhibition of monoamine oxidase but not with restoration of the serotonin content of several regions of the brain. Harmaline had a reversible effect while that of pheniprazine persisted for weeks. Clorgyline in low doses (0.5-1.0 mg/kg), at which it is a specific inhibitor of type A monoamine oxidase, antagonized the action of reserpine for over 2 weeks. Deprenyl and its demethylated analog failed to suppress the reserpine-induced waves even at 10 times the dose of clorgyline when they should have completely inhibited type B monoamine oxidase. In contrast to antagonism of reserpine, suppression of rapid eye movement sleep by these monoamine oxidase inhibitors could be temporally dissociated from their inhibition of the enzyme. It is concluded that suppression of the induction of ponto-geniculo-occipital waves by reserpine after administration of the monoamine oxidase inhibitors is a specific effect of these drugs and is related to inhibition of type A monoamine oxidase. Suppression of rapid eye movement sleep is probably a nonspecific effect and not related to inhibition of the enzyme.

Animals↗

PubMedDate not supplied

[Type A and B monoamine oxidase activity in hyperbaric oxygenation].

Substrate specificity of monoamine oxidase (MAO) of the A type from rat brain and liver tissues was altered after exposure of rats to an increased oxygen pressure [4 ati O2, 1 hr]. Simultaneously with a decrease in monoamine deaminating activity the enzyme acquired an ability to deaminate several substances, which are not MAO substrates in normal state, in particular, aminosugars. Activity of MAO of the B type was not altered in brain under hyperoxia. Alterations in catalytic properties of MAO of the A type were apparently important in development of the oxygen intoxication.

Animals↗

PubMed1981

The role of phospholipid in the multiple functional forms of brain monoamine oxidase.

The nature of phospholipid requirement and lipid-protein interactions for the multiple functional forms of monoamine oxidase was investigated by rebinding the purified phospholipid to a lipid-depleted brain mitochondrial preparation. It was found that phosphatidylinositol uniquely stimulated the monoamine oxidase A activity to 80% over that in the original intact mitochondria. Other negatively charged phospholipids, although not as potent, could fully or partially reactivate the A or the B activity. Phosphatidylserine was relatively more effective in restoring the B activity. Phosphatidylcholine, a zwitterionic phospholipid, reconstituted 70% of the A activity but did not influence the B. More importantly, efficiency-gradient analyses indicated a distinct nature in the mechanism of lipid-protein interactions for the negatively charged and the zwitterionic phospholipids. The potency of the negatively charged phospholipid decreased sharply with increasing lipid molecules. No further stimulation could be detected when the lipid to protein ratio reached about 30 molecules of the negatively charged phospholipid for 100,000 daltons of membrane protein. The negatively charged phospholipid appeared to bind directly to the monoamine oxidase protein boundary with a high affinity. Phosphatidylcholine might reassociate as the membrane fluid bilayer, which in turn modulated the monoamine oxidase A activity.

Animals↗