Biosynthèse in vitro d'octopamine par le système nerveux et le cœur du mollusque gastéropodeHelix pomatia

Summary The tyrosine is decarboxylated in vitro by the central nervous tissue and by the intracardiac nervous tissue ofHelix pomatia by aromatic amino-acid decarboxylase. The tyramine obtained is the partially transformed into octopamine by tyramine--hydroxylase. The inhibition of monoamine oxidase favours apparition of the 2 amines. The monoamine oxidase seems able to regulate their synthese and to assure their inactivation.

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Biosynthèse in vitro d'octopamine par le système nerveux et le cur du mollusque gastéropodeHelix pomatia

     

Monoamine oxidase activity in rat erythrocytes: Evidence for its localization in reticulocyte mitochondria

Summary During growth of young rats, monoamine oxidase activity in erythrocyte membrane preparations decreases more rapidly than reticulocyte concentrations in the respective blood samples. Since reticulocytes lose their mitochondria prior to the substantia reticulo-filamentosa, the non-linear correlation between monoamine oxidase activity and reticulocyte counts indicates that erythrocyte monoamine oxidase is located in reticulocyte mitochondria.This work was supported by a grant from the Deutsche Forschungsgemeinschaft.     

Further studies on the effect of 6-hydroxydopamine in retinal development.

Neonatal albino rats treated with 6-hydroxydopamine revealed depletion of rhodopsin and monoamine oxidase in their retinas.     

Monoacylcadaverines as substrates for both monoamine oxidase and diamine oxidase; low rates of activity

Summary Monoacetylcadaverine and monopropionylcadaverine were found to be substrates for both rat liver monoamine oxidase and hog kidney diamine oxidase, but all the K_m-values for the oxidases were very high. The amines were common substrates for type A and type B monoamine oxidase.     

Distribution of type A and B monoamine oxidase activities in the central nervous system of rat and chick

Summary The distribution of type A and B monoamine oxidase (MAO) activities in the central nervous system (CNS) of rat and chick was investigated using 5-hydroxytryptamine and -phenylethylamine as specific substrates. The distribution of type A MAO was similar to that of type B MAO in rat CNS, but quite different in chick CNS. This may be ascribed to the difference in animal species. The major part of MAO activity in the spinal cord was found to be type A.     

Mineralocorticoid treatment and the adrenalectomy-induced increase in monoamine oxidase activity

Summary Bilateral adrenalectomy in the rat results in an increase in heart monoamine oxidase activity in animals drinking water and in animals drinking 0.9% saline. Daily administration of deoxycorticosterone acetate prevented the increased monoamine oxidase activity in the animals drinking saline but not in those drinking water.Acknowledgment. This work was supported in part by a grant from the American Heart Association — Louisiana, Inc.     

Further studies on the effect of 6-hydroxydopamine in retinal development

Summary Neonatal albino rats treated with 6-hydroxydopamine revealed depletion of rhodopsin and monoamine oxidase in their retinas.Acknowledgments. The author wishes to dedicate this paper to his family for their continuous support and to ProfessorsA. K. S. Ho andD. B. Meyer for their understanding and friendship.     

Identification of type A monoamine oxidase in mouse and rabbit liver mitochondria

Summary Type A monoamine oxidase was identified in liver mitochondria of mouse and rabbit. 5-Hydroxytryptamine was a common substrate for type A and type B monoamine oxidase in these enzyme preparations where its concentration was 1.0 mM.     

Distribution of monoamine oxidase in hippocampal region of the rat

The distribution and development of type A and type B monoamine oxidase (MAO) activities in the hippocampal region of the rat was investigated with biochemical microdetermination. Type A MAO is absolutely dominant and unevenly distributed in the hippocampus. The development of type A MAO in the hippocampus seems to be delayed and reachs adult levels by the 30th day after birth.     

Affinity chromatography of monoamine oxidase

Summary A method is described for the purification of pig liver monoamine oxidase by affinity chromatography, using a colum with covalently bound pargyline.Acknowledgment. The authors wish to thank the University Research Council for financial support.     

MAO inhibition,an unlikely mode of action for chlordimeform

Summary Inhibition constants of several formamidines, their corresponding formanilides and other representatives of compounds derived from aniline, such as phenylureas, N-phenyl-carbamates and acylanilides, were determined for rat liver monoamine oxidase. The reversability of the inhibition and the lack of correlation between inhibition potencies and toxicities of the compounds tested add to the opinion that MAO inhibition is not a prominent factor in chlordimeform poisoning.     

Distribution of monoamine oxidase in hippocampal region of the rat

Summary The distribution and development of type A and type B monoamine oxidase (MAO) activities in the hippocampal region of the rat was investigated with biochemical microdetermination. Type A MAO is absolutely dominant and unevenly distributed in the hippocampus. The development of type A MAO in the hippocampus seems to be delayed and reachs adult levels by the 30th day after birth.     

Differential activation of two monoamine oxidase types by oxygen

Summary The stimulation of rat brain monoamine oxidase activity by oxygen is shown to be type-selective, type B being much more strongly stimulated than type A.Pargyline and clorgyline were gift samples from Abbott Laboratories, USA and May and Baker Ltd, England respectively     

Effects of thyroidectomy on monoamine oxidase activities toward tyramine and serotonin in the circumventricular nuclei of the rat

Summary Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei.     

Effects of thyroidectomy on monoamine oxidase activities toward tyramine and serotonin in the circumventricular nuclei of the rat.

Following thyroidectomy, monoamine oxidase (MAO) activities toward tyramine decreased significantly by 20% in the nucleus periventricularis and the nucleus arcuatus among the 3 hypothalamic nuclei of the rat, while MAO activity toward serotonin decreased significantly by 10% only in the nucleus periventricularis. It is suggested that thyroidectomy induced selective changes on the multiple forms of MAO in the discrete circumventricular nuclei.     

Abschwächung der Noradrenalin-Wirkung auf die isolierte Aorta bei Hemmung der Monoaminoxydase

Summary Twenty hours after pretreatment of rabbits with the monoamine oxidase inhibitor N₂-isopropyl-isonicotinic acid hydrazide (IIH) the norepinephrine induced contraction of the isolated aorta was significantly reduced; the 5-hydroxytryptamine sensitivity could not be changed significantly. Isonicotinic acid hydrazide (INH), a weak monoamine oxidase inhibitor, had no significant effect on the norepinephrine and 5-hydroxytryptamine sensitivity of the aorta.     

Multiplicity of monoamine oxidase in chick brain.

The substrate- and inhibitor-related characteristics of monoamine oxidase (MAO) were studied on chick brain mitochondria. It was found that neither 5-hydroxytryptamine nor beta-phenylethylamine is the specific substrate for type A and type B MAO in chick brain.     

The stimulation of rat brain monoamine oxidase by dietary lithium chloride.

Lithium chloride administered to rats in drinking water for 30 days caused an increase of whole brain monoamine oxidase specific activity to approximately 140% of control. Carboxylesterase and formyltetrahydrofolate synthetase activities were not affected by Li+ either in vivo or in vitro.     

Normetanephrine and metanephrine oxidized by both types of monoamine oxidase

Both normetanephrine and metanephrine were found to be oxidized by both types of monoamine oxidase in mouse liver mitochondria. Both Km and Vmax values of type B MAO for both substrates were higher than those of type A MAO, which caused the shift of inhibition curves with clorgyline and deprenyl according to the increase in substrate concentration.     

Enhancement of ethanol-induced sleep by whole oil of nutmeg

In young chickens, the whole oil of nutmeg (200 mg/kg) increased the duration of sleep induced by ethanol (1--4 g/kg), particularly deep sleep. Iproniazid (50-400 mg/kg), a monoamine oxidase inhibitor, did not mimic this effect.