Metabolism of Dopamine and Noradrenaline in Rabbit Caudate Nucleusin vitro

Slices of rabbit caudate nuclei were incubated with labeled dopamine or noradrenaline. It was found that the catabolism of dopamine proceeded at a rate higher than that of noradrenaline. Deamination of both amines was the major pathway of catabolism with O‐methylation playing a relatively minor role. This was detected by isolating and quantitating each of the known deaminated and O‐methylated products of each amine. Pretreatment of rabbits with protriptyline did not inhibit the amount of catabolites formed or the amount of amines retained by the tissue. Synthesis of noradrenaline from dopamine could not be detected in this preparation. The results of this study indicate that the dopamine containing neurons of the caudate nucleus differ in some of their properties from the noradrenaline containing neurons in the cerebral cortex.