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At least 1,171 records · Page 65Linked to original sources
PubMed1971

Role of noradrenaline and 5-hydroxytryptamine in tetrahydronaphthylamine-induced temperature changes in the rat.

1. Intraperitoneal administration of graded doses of tetrahydronaphthylamine (THN) to rats caused a dose dependent decrease in body temperature.2. Intracisternal injection of graded doses of THN induced hypothermia, and implantation of crystalline THN rostral to the medial preoptic area and caudal to the striatum, caused hyperthermia.3. Pretreatment of the rats with a MAO inhibitor changed the hypothermia into hyperthermia.4. Intraperitoneal injection of 5-hydroxytryptophan caused a hypothermia which could be reversed into hyperthermia when the rats were pretreated with a MAO inhibitor.5. Pretreatment with parachlorophenylalanine enhanced the THN-induced hypothermia.6. Depletion of brain monoamines by Ro-4-1284 in combination with an inhibition of the biosynthesis of noradrenaline (diethyldithiocarbamate) changed the THN-induced hypothermia into hyperthermia.7. It is concluded that THN affects body temperature in rats by two central mechanisms, viz. a decrease mediated by noradrenaline, probably in the hypothalamus, and an increase which might be mediated by 5-hydroxytryptamine rostral to the medial preoptic area.

Animals↗
PubMed1971

Passage into the rat brain of dopa and dopamine injected into the lateral ventricle.

1. The green fluorescence of catechols of the brain was studied in rats after intraventricular injection of L-dopa or dopamine in untreated rats as well as in rats in which dopa decarboxylase (DC) was inhibited by Ro 4602, or the monoamine oxidase by nialamide.2. From the patterns of fluorescence obtained in these conditions, it is concluded that in the areas close to the liquor space dopa is rapidly taken up by the endothelium of the brain capillaries and then converted into dopamine; when the DC is inhibited the dopa passes freely from the endothelium into the brain tissue.3. On the other hand, dopamine passes from the liquor space via the ependyma directly into the brain tissue and from there into the capillary endothelium which is thus permeable to the amine in the direction from the brain tissue, in contrast to the impermeability in the direction from the capillary lumen.

Animals↗
PubMed1971

Effect of inhibition of catecholamine synthesis on central catecholamine-containing neurones in the developing albino rat.

1. Tyrosine hydroxylase is thought to be the rate limiting enzyme step in catecholamine biosynthesis. Inhibition of this enzyme using alpha-methyl-p-tyrosine resulted in a time dependent depletion (and repletion) of formaldehyde induced fluorescence in catecholamine-containing neurones of the central nervous system in developing and adult rats.2. Dopamine-containing neurones were depleted faster and more completely than noradrenaline-containing neurones.3. The extent of depletion caused by alpha-methyl-p-tyrosine in the initial 6-9 h period was more or less comparable in young and adult rats from the age of 1 week onwards; this suggests that catecholamine turnover increases with age and parallels the increase in catecholamine levels.4. The extent of depletion (and repletion) 18 h after administration of the inhibitor varied in animals of different age.5. Administration of a monoamine oxidase inhibitor just before administration of alpha-methyl-p-tyrosine resulted in a reduction of the extent of depletion caused by the latter drug, indicating that monoamine oxidase is important for the breakdown of catecholamines in rats of all ages.6. It is suggested that the catecholamine-containing neurones of the newborn are biochemically as well as functionally differentiated before completion of morphological differentiation.

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PubMed1973

Histochemical localization of adrenergic nerves in the guinea-pig trachea.

1. Specific catecholamine fluorescence was demonstrated in guinea-pig trachea in fine, varicose, nerve fibres running parallel to the tracheal smooth muscle fibres.2. The density of nerves in tracheal smooth muscle was greater at the laryngeal end than at the bronchial end of the trachea.3. The findings confirm pharmacological evidence for an adrenergic innervation of the guinea-pig isolated tracheal chain preparation.

Animals↗
PubMed1973

A histochemical study of extraneuronal accumulation of noradrenaline in the guinea-pig trachea.

1. Accumulation of noradrenaline in extraneuronal tissue of the guinea-pig trachea has been studied by the use of the fluorescence histochemical technique of Falck and Hillarp.2. After incubation in solutions of noradrenaline, fluorescence developed in cellular structures (tracheal smooth muscle, vascular smooth muscle and endothelium, fibroblasts and chondroblasts), in the intercellular matrix of the cartilage and throughout the loose connective tissue of the adventitia and submucosa.3. The effect of various experimental procedures on the development of this fluorescence has been examined i.e. incubation with noradrenaline at reduced temperature (0 degrees C), removal of fluorescence by washing with Krebs solution at 37 degrees C or 0 degrees C, incubation with phenoxybenzamine (10(-4)M) or metanephrine (10(-4)M).4. From these observations it has been concluded that noradrenaline accumulates in the trachea:(a) in cellular structures where it is firmly bound, i.e. not easily removed by washing at 0 degrees C, and where the accumulation is prevented by phenoxybenzamine, metanephrine or cold.(b) in the intercellular matrix of the cartilage where it is also firmly bound, but where the accumulation is not prevented by phenoxybenzamine, metanephrine or cold. This probably represents binding to sulphated mucopolysaccharides.(c) in the adventitia and submucosa where it is loosely bound and easily removed by washing.5. Some implications of these findings in pharmacological experiments with guinea-pig trachea are discussed.

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