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

Abstract

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.

Influence of the Hypophysio-Adrenocortical System on the Metabolism of3H-Adrenaline in the Hypothalamus, Hypophysis and the Rest of the Brain of Rats

“…3 as glucocorticoids in regulation of catecholamine synthesis and metabolism (Holzbauer and Youdim 1973;Raza-Bukhari et al 1976). A short-term adrenalectomy also increases activities of enzymes MAO (Parvez and Parvez 1973c;Parvez et al 1976) but a chronic adrenalectomy is less effective than hypophysectomy. Our present data is in agreement with the latter suggestion since adrenalectomy produces less marked effects than hypophysectomy on all the process of 3 H-adrenaline metabolic fate.…”

“…The inactivation of adrenal glucocorticoidogenesis results in decreased adrenaline storage and PNMT activity in the adrenal gland (Wurtman and Axelrod 1965). Adrenalectomy or hypophysectomy of the fetal or neonatal rats augments acitivity of the enzymes of monoamine metabolism (Parvez and Parvez 1973 a;Parvez, Gripois and Parvez 1976). Pharmacological inhibition of 11-beta-hydroxylase by metopirone administration in rats results in marked increases of MAO and COMT activities.…”

Influence of Perinatal Adrenalectomy and Adrenal Demedullation upon Development of Enzyme Catechol-<i>o</i>-Methyltransferase in Peripheral Organs of the Rat

“…The results of a similar study about the influence of adrenalectomy at birth upon the development of enzyme monoamine oxidase in young rats are only in partial agreement with the present findings (23) since adrenalectomy resulted in a highly significant increase in cardiac monoamine oxidase activity. The effects on cardiac monoamine oxi dase activity were also induced by the lack of adrenal cortex (23). The adrenal ectomy of the adult rat produces significant increase in the output of catechol amine acid metabolites (13,14,20).…”