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.     

Effects of neurochemical lesions restricted to spinal cord monoaminergic neurons on blood pressure and sympathetic activity of spontaneously hypertensive rats

Intraspinal (i.s.) injection of 6-hydroxydopamine or 5,7-dihydroxytryptamine in newborn spontaneously hypertensive rats (SHR) resulted, in the adult animal (30-week-old), in a marked decrease of spinal cord noradrenaline (NA) or 5-hydroxytryptamine (5-HT) levels, respectively. Since both neurotoxin- and vehicle-injected rats developed full hypertension and had similar plasma catecholamine concentrations, it is concluded that in SHR neither spinal cord NA nor 5-HT play a major role in development and maintenance of hypertension.     

Multiplicity of monoamine oxidase in chick brain

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

Drug uptake by lung slices from paraquat-pretreated rats

Summary Lung slices from male Sprague-Dawley rats pretreated with paraquat (PQ) (100 moles·kg^–1, i.v.) 16 h before sacrifice, accumulated less PQ in vitro than lung slices from saline-treated controls. Neither lung slices from PQ-pretreated nor saline control animals released (effluxed) PQ accumulated in vitro. The accumulation and efflux of imipramine and 5-hydroxytryptamine by lung slices was unaffected by prior in vivo administration of PQ.     

In vivo inhibition by dopamine of 5-hydroxytryptamine-stimulated ovarian maturation in the red swamp crayfish,Procambarus clarkii

In vivo dopamine antagonizes the ovary-stimulating action of 5-hydroxytryptamine in the red swamp crayfish,Procambarus clarkii.     

The effect of γ-irradiation on the amount of 5-hydroxytryptamine in the gut and spleen in the early phase after irradiation

Résumé 24 et 48 h après irradiation- (900 r) la quantité de 5-hydroxytryptamine dans l'intestin du rat n'a pas changé de manière significative. La quantité de 5-hydroxytryptamine dans la rate du rat, exprimée par g de tissu frais a augmenté. Le prétraitement avec de la cystéamine abaisse nettement la quantité de 5-hydroxytryptamine dans la rate, après l'irradiation.     

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.     

Cardioactive peptides of the CNS of the pulmonate snailLymnaea stagnalis

Summary In the pulmonate snailLymnaea stagnalis the cardioactive effects (tested on isolated auricles) of acetylcholine (ACh), 5-hydroxytryptamine (5-HT), the bivalve tetrapeptide FMRFamide, and of chromatographically separated snail brain substances have been established. Besides ACh and 5-HT, in brain extracts, small FMRFamide-like and large cardioexcitatory peptides were found.     

Comparison of diurnal and nocturnal rates of 5-hydroxytryptamine turnover in the rat mediobasal hypothalamus

Rates of 5-hydroxytryptamine (5-HT) turnover in the mediobasal hypothalamus of male rats were estimated using pharmacological methods during the daytime and at night. Concentrations of 5-HT in this hypothalamic area were higher nocturnally than diurnally; this was apparently due to increased 5-HT synthesis and decreased 5-HT catabolism at night.     

Shape change reaction of platelets in protein-free medium: ultramorphology.

Transmission and scanning electron microscopy indicate that rabbit platelets incubated in protein-poor medium retain their reactivity to shape change-inducing agents such as 5-hydroxytryptamine, adenosine-5'-diphosphate and chlorpromazine. Such platelets may be used as models for drug-membrane interactions, e.g. in neuronal cells.     

Inhibition of pig kidney dopa decarboxylase by coenzyme-5-hydroxytryptophan adducts

The effect of N-(5'-phosphopyridoxyl)-L-5-hydroxytryptophan, N-(5'-phosphopyridoxyl)-D-5-hydroxytryptophan and N-(5'-phosphopyridoxyl)-5-hydroxytryptamine on the reactivation of apoDopa decarboxylase to holoenzyme has been investigated. The different degree of inhibition exerted by these adducts has been interpreted on the basis of a different orientation of the 2 isomers of 5-HTP at the active of Dopa decarboxylase.     

Pyrogen fever in rabbits pretreated with p-chlorophenylalanine or 5, 6-dihydroxytryptamine.

The hyperthermic effect of a bacterial pyrogen has been studied in rabbits pretreated or not with p-chlorophenylalanine or 5, 6-dihydroxytryptamine. The results obtained indicate that a selective reduction of cerebral 5-hydroxytryptamine levels by these drugs do not significantly affect pyrogen hypertermia.     

Effects of S-adenosylmethionine and S-adenosylhomocysteine on in vivo synthesis of noradrenaline and serotonin in different parts of the rat brain]

S-adenosylmethionine (0,1 mg/kg/ip) decreases in vivo, norepinephrine (NE) synthesis and does not affect 5-hydroxytryptamine (5 HT) synthesis in the Rat brain. S-adenosylhomocysteine (7 mg/kg/ip) increases NE synthesis and decreases 5 HT synthesis. Neither nucleoside affects dopamine synthesis.     

Über die Entstehung von Serotonin aus 5-Hydroxytryptophan nach UV.-Bestrahlung

Summary UV.-irradiation of a 5-hydroxytryptophan solution results in formation of 5-hydroxytryptamine (serotonin) the yield being higher than that of histamine in a histidine solution under similar conditions. The possible importance of these findings, for biological effects of UV.-irradiation is discussed.     

Comparison of diurnal and nocturnal rates of 5-hydroxytryptamine turnover in the rat mediobasal hypothalamus

Summary Rates of 5-hydroxytryptamine (5-HT) turnover in the mediobasal hypothalamus of male rats were estimated using pharmacological methods during the daytime and at night. Concentrations of 5-HT in this hypothalamic area were higher nocturnally than diurnally; this was apparently due to increased 5-HT synthesis and decreased 5-HT catabolism at night.Supported by NIH grant RR07187 (TSK) and NIH grant HD10202 (Neuroendocrine Core).     

Thrombozytose und Eosinopenie bei Ratten nach einmaliger 5-Oxytryptamininjektion

Summary After injection of a high dose of 5-hydroxytryptamine into rats, the blood reveals a strong increase of the blood platelets and a definite decrease of the eosinophiles. The maxima of increase and decrease are in temporal accordance.     

Die Wirkung von D-Lysergsäure-diäthylamid (LSD 25) und 5-Oxytryptamin auf die Chromatophoren vonPoecilia reticulatus

Summary D-lysergic acid diethylamide (LSD 25) has a characteristic effect on the chromatophores of the female fish guppy (Poecilia reticulatus). This effect can be prevented by prophylactic administration of 5-hydroxytryptamine (serotonin, enteramine).     

A response to monoamines inPeripatopsis moseleyi (Onychophora)

Summary Preparations of longitudinal muscle respond to catecholamines if the ventral nerve cords are present, and also to 5-hydroxytryptamine. The response to 5HT is complex if the central nervous system is present, but muscle alone is probably inhibited.Acknowledgments. It is a pleasure to thank Professor A.C. Brown for providing facilities in the Zoology Department, University of Cape Town, and Mr L.R. Alexander and his colleagues for help in obtaining materials.     

The presence of monoamines in the nervous system ofPeripatopsis (Onychophora)

Summary Preliminary observations of formaldehyde-induced fluorescence support the suggestion that monoamines such as noradrenaline, dopamine and 5-hydroxytryptamine are transmitter agents in the central nervous system of Onychophora.Acknowledgments. We wish to thank Dr M. Fillenz for valuable advice and for generously enabling this work to be carried out, and we are indebted to Dr V. van der Lande for material.     

Circadian rhythms of serotonin and the electrical activity of the frontal ganglion of the cockroach,Periplaneta americana

Summary Rhythmic circadian variations in the spontaneous electrical activity of the frontal ganglion (FG) of the cockroach,Periplaneta americana, have been shown, and the neurotransmitter (NT) involved in this activity has been identified as serotonin (5-hydroxytryptamine, 5-HT). During the 24-h day, the diurnal variations in the electrical activity and the levels of 5-HT and its immediate metabolite 5-hydroxyindole acetic acid (5-HIAA) were maximal at 24.00 h and minimal at 12.00 h.