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

Abstract

Possible correlation between modified state of the adrenocortical system and the metabolic fate of 3H-adrenaline in central regions was studied. The formation of 3H-acid metabolites from 3H-adrenaline showed high increase in brain and hypothalamus of hypophysectomized rats from the value of normal animals. Adrenalectomy was also found to be associated with increased acid metabolite formation in the whole of the brain. Preadministration of metopirone increased formation of acid metabolites in the hypothalamus and hypophysis of normal rats. The transformation of radioactive normetanephrine was significantly higher in the hypothalamus of rats administered with elliptone as well as with metopirone. The hypophysis showed increase in metanephrine formation only by pretreatment with elliptone. Brain tissue demonstrated increased rate of normetanephrine formation after adrenalectomy and hypophysectomy. Hypophysectomy increased physiological accumulation of 3H-adrenaline in all the three regions studied but the maximal effect was observed in the hypothalamus. The preadministration of elliptone and metopirone decreased accumulation of labeled adrenaline in the brain and hypophysis of normal rats. The results suggest that inactivation of adrenocortical system either pharmacologically or physiologically leads to activation of the the processes of catecholamine metabolic degradation whereas the physiological accumulation of adrenaline slows down and this conclusion is valid for a great majority of observations presented in this study.