The Effect of Age and Thyroid Hormones on the Monoamine Oxidase of Rat Heart

Novick, William J.

doi:10.1210/endo-69-1-55

Cited by 64 publications

(14 citation statements)

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“…has been conducted. The enzyme activity was Novick, 1961;Karki, Kuntzman & Brodie, 1962; measured in four discrete brain regions and in three Bennett & Giarman, 1965;Vaccari, Maura, Marchi & peripheral organs, five different substrates being used Cugurra, 1972;Youdim, Holzbauer & Woods, 1974).…”

Section: Introductionmentioning

confidence: 99%

Ontogenesis of Enzyme Systems Deaminating Different Monoamines

Blatchford

Holzbauer

Grahame-Smith

et al. 1976

British J Pharmacology

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I A detailed investigation into the postnatal development of the activity of the enzyme monoamine oxidase (MAO) in the rat and domestic pig was carried out. 2 MAO activity was measured in littermate male rats aged between 3 and 122 days belonging to six breeding colonies. The tissues studied were three brain regions in which monoamines may play a role in neuronal transmission (septum, hypothalamus, corpus striatum) and, for comparison, in the cerebellum. Liver, heart and adrenal glands were the peripheral organs studied. The following substrates were used to measure MAO activity in each tissue homogenate: kynuramine, tyramine, dopamine, tryptamine and 5-hydroxytryptamine (5-HT). 3 MAO activity towards kynuramine, tyramine and dopamine increased after birth in all brain regions and also in the liver, to reach maximal values between days 40 and 80. In the heart and the adrenal glands enzyme activity remained low up to 30-40 days and then increased steeply. This was the case in all litters examined. 4 All tissues deaminated more tyramine than dopamine. In the liver, the ratio of the quantities of tyramine deaminated/dopamine deaminated was approx. 2 at all ages. In the homogenates of whole brains (including or excluding the hypothalamus and striatum) this ratio was also 2 at all ages. In contrast in the isolated striatum and hypothalamus it was first much higher and reached a value of 2 only at an age of about 20 days. This may indicate an independent development of a dopamine and a tyramine deaminating enzyme system in discrete brain regions. It was suggested, that the low ability to deaminate dopamine in discrete brain regions may be due to the local presence of an enzyme inhibitor which becomes too diluted to be active in homogenates of whole brain. 5 Deamination of tryptamine in the striatum decreased between day 5 and 20 in 3 out of 4 colonies tested. There was a large fall in the deamination of 5-HT in all tissues of one group of rats, but in another 4 groups the tissues of the 5 day old rats deaminated smaller amounts of 5-HT than those of the older rats. 6 Purified hypothalamic mitochondria from 40 day old rats deaminated more tyramine and dopamine but not tryptamine per mg protein than those from 5 day old rats. 7 In the domestic pig there was a significant rise in the values in hippocampal MAO activity towards dopamine and tyramine from the foetus (55 day gestation) to the 1 week old piglet. A further steady rise up to week 6 was indicated, but this rise was not statistically significant. The difference between rat and pig probably reflected the much higher degree of maturity of the latter at birth. 8 In the hippocampus of the pig the ratio between the amount of tyramine deaminated/dopamine deaminated decreased from > 10 (foetus) to 4.8 in the 6 week old pig and 2 in the adult.

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Section: Introductionmentioning

confidence: 99%

Ontogenesis of Enzyme Systems Deaminating Different Monoamines

Blatchford

Holzbauer

Grahame-Smith

et al. 1976

British J Pharmacology

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“…In rat heart the activity of MAO increases linearly with the weight of the animal throughout life (19), while in the kidney, at birth, it is half of the adult (14,22). The MAO activity in the brain and liver of newborn is '/4 to V3 of the adult (13,18,35).…”

Section: Introductionmentioning

confidence: 98%

Corticosteroid Influence in the Postnatal Development of Monoamine Oxidase Activity in the Young Rats

Parvez¹,

Gripois²,

Parvez³

1976

Neonatology

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Developmental changes in total activity of enzyme monamine oxidase (MAO) were studied in heart, liver, kidney and lung of normal young rats and rats adrenalectomized at birth. Determination of total enzyme activity was made utilizing ¹⁴C-tryptamine as a substrate. MAO activity was measured during 20 days of postnatal life in normal and adrenalectomized young rats. Adrenalectomy was followed by transitory alterations in the enzyme development. MAO activity in the heart of adrenalectomized rats was higher than their respective controls. Adrenalectomy decreased enzyme activity in liver and lung. The preadministration of hydrocortisone to adrenalectomized young rats restored MAO activity to normal levels in all the tissues studied. The possible mechanisms for corticosteroid action in the development of MAO activity have been discussed.

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“…1-4-3-4) in different organs, especially in the heart. In the adult rat (Utley, 1964 ;Lyles and Callingham, 1974 ;Callingham and Lyles, 1974 ;Tong and d'lorio, 1976) as well as in the newborn (Novick, 1961 ;Fernandez, 1976, 1977a) and the fetus (Gripois and Fernandez, 1977b), hyperthyroidism is followed by an increase in cardiac MAO activity, while hypothyroidism leads to a decrease.…”

Section: Introductionmentioning

confidence: 99%

On the nature of monoamine oxidase control by thyroxin in the heart, brain and brown adipose tissue of the developing rat

Gripois¹

1978

Ann. Biol. anim. Bioch. Biophys.

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Summary. The aim of the present work was to determine whether the increase in monoamine oxidase activity previously found in hyper-and hypothyroid rats, was due to thyroxin effects on enzymatic activity or to variations in enzyme synthesis.The rate of synthesis of monoamine oxidase in young hyper-and hypothyroid rats has been studied by measuring the recovery of enzymatic activity 7 days after irreversible inhibition by Pargyline. Hyperthyroidism was followed by an increase in the rate of synthesis of monoamine oxidase in the heart and a decrease in the brain. Hypothyroidism led to an increase in brown adipose tissue.Thyroxin increased cardiac monoamine oxidase activity in vitro in the late fetal period, but not in the newborn or the adult.The results show that thyroxin controls monoamine oxidase activity in the newborn rat primarily by acting on the rate of synthesis of the enzyme.Introduction.

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The Effect of Age and Thyroid Hormones on the Monoamine Oxidase of Rat Heart

Cited by 64 publications

References 0 publications

Ontogenesis of Enzyme Systems Deaminating Different Monoamines

Ontogenesis of Enzyme Systems Deaminating Different Monoamines

Corticosteroid Influence in the Postnatal Development of Monoamine Oxidase Activity in the Young Rats

On the nature of monoamine oxidase control by thyroxin in the heart, brain and brown adipose tissue of the developing rat

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