The Involvement of Catecholamines and Polypeptide Hormones in the Multihormonal Modulation of Rat Hepatic Zinc Thionein Levels

Abstract

Catecholamines can induce rat hepatic zinc thionein to high levels via alpha 1- and beta 2-adrenoceptors. Polypeptide hormones (glucagon and angiotensin II) are also inducers, but only to the moderate levels attained by glucocorticoids (dexamethasone). Turpentine induced inflammation stimulates the synthesis of ZnMT, but this process is not mediated by catecholamines. Phorbol esters, which are tumor promoters, can stimulate protein kinase C. Angiotensin II and alpha 1-agonists activate protein kinase C via diacylglycerol release from phosphatidylinositol-4,5-diphosphate. Phorbol esters can also stimulate the synthesis of rat hepatic zinc thionein, implicating protein kinase C activation in this induction. The multihormonal modulation of metallothionein gene activation has become increasingly more complex.