Regulation and inheritance of dopamine-beta-hydroxylase

Dopamine-beta-hydroxylase (DBH) is unique among the catecholamine biosynthetic enzymes in that release from sympathoadrenal cells during neurotransmission is an integral part of the enzyme's physiology. Because of this unique attribute, the metabolic pathways regulating DBH cannot depend solely upon intraneuronal processes. This manuscript summarizes evidence relating to the regulation of DBH metabolism in the rat. Levels of DBH in the circulation, which derive from release of sympathoadrenal cellular enzyme stores, are genetically determined; even though inherited, circulating DBH levels bear no apparent consistent relationship to cellular enzyme levels or to sympathoadrenal function. These findings suggest that processes regulating neuronal release of DBH are separate from other processes regulating disposal of the circulating enzyme. We have evaluated the circulating DBH disposal pathways by standard metabolic techniques. Our data strongly suggest that clearance of DBH from the circulatory compartment is a main, and perhaps the primary, disposal mechanism for cellular enzyme stores.