Immunocytochemical localization of tyrosine hydroxylase in rat adrenal medulla by the peroxidase labeled antibody method: effects of enzyme activation on ultrastructural distribution of the enzyme.

A monospecific antibody against tyrosine hydroxylase (TH), purified from a transplantable rat pheochromocytoma, was produced in rabbits. Immunohistochemical techniques were employed in order to determine if a relationship exists between the subcellular distribution of TH and the level of activation of the enzyme in the rat adrenal medulla. Tyrosine hydroxylase activity in adrenals removed from non-stressed rats following pentobarbital anesthesia was found to be 12.9 +/- 1.0 nmol DOPA formed x mg protein-1. The use of ether anesthesia (17.9 +/- 2.0 nmol DOPA formed x mg protein-1), and the administration of electroconvulsive shock (ECS) followed by decapitation (35.9 +/- 2.0 nmol DOPA formed x mg protein-1) was associated with an acute activation of adrenal TH. The subcellular distribution of TH within the cytosol of chromaffin cells from animals subjected to anesthesia or ECS, as determined by immunocytochemical techniques, was similar. In all treatment groups chromaffin cells were found which had TH associated with some chromaffin granules. The percentage of chromaffin granules which appeared to contain TH was lower in animals subjected to ECS plus decapitation as compared with anesthetized animals. These observations suggest that the activation of adrenal medullary TH is not associated with a shift in the subcellular distribution of the enzyme from the cytosol to membranous structures.