Effects of long-term administration of pyrogallol on tissue catecholamine levels, monoamine oxidase and catechol-O-methyl-transferase activities in the rat

Abstract

Experiments have been performed to obtain evidence that the altered levels of endogenous catecholamines produced by pyrogallol treatment may be regulated by an adaptive change in the activities of catechol-O-methyltransferase and monoamine oxidase. 5 The effects of chronic administration of pyrogallol on the content of catecholamines and on the activity of catechol amine inactivating enzymes of rat organs have been studied. The catecholamine content in the brain and in the adrenals was not altered significantly by pyrogallol treatment. It was usually smaller in the heart of treated animals than in the controls. Catechol-O-methyltransferase activities in the liver, brain and heart remained unchanged or were slightly higher under chronic pyrogallol administration. The acute responsiveness of catechol-O-methyltransferase to pyrogallol injection was not modified by chronic treatment with pyrogallol. Monoamine oxidase activity was not influenced in the brain. From the third week of treatment it was increased in the heart and decreased in the liver. No evidence for the occurrence of adaptive changes in the activities of catecholamine metabolizing enzymes was found, since no change or very small changes were observed in the endogenous catecholamine levels and in the activities of tissue monoamine oxidase and catechol-O-methyltransferase.