Sulfate Conjugation of Dopamine in Rat Brain: Regional Distribution of Activity and Evidence for Neuronal Localization

Abstract: Brain tissue contains at least two forms of phenolsulfotransferase that are involved in the sulfate conjugation of biogenic amines and their metabolites. Two apparent K_m values were obtained for p‐nitrophenol at pH 7.4 (0.6 μM and 0.3 mM) but only one enzyme had the capacity to conjugate dopamine (K_m=130 μM). Dopamine sulfotransferase activity was found to vary 17‐fold in different brain regions, with the highest levels in diencephalon, hippocampus, and striatum. To determine the cellular localization of the enzymes, phenolsulfotransferase activity was measured in striatum following selective destruction of striatal neurons by stereotaxic injection of 2 μg kainic acid. Fourteen days after injection the catecholamine sulfotransferase activity in the lesioned striatum was reduced to approximately 40–50% of that in the control contralateral striatum. There was a statistically significant correlation between the ratio of lesioned to control activity for the sulfotransferase and the neuronal marker enzymes glutamate decarboxylase and neuron‐specific enolase. p‐Nitrophenol sulfotransferase activity was also decreased in the lesioned striatum. These results suggest that PST activity is present within the kainic acid‐sensitive neurons of the striatum. The regional variation in activity, together with the results of the kainic acid studies, suggest that sulfate conjugation of biogenic amines and their metabolites in brain may take place within specific types of neurons.