an increase of free 3,4-dihydroxyphenylethylamine ( da , dopamine ) in the rat brain such as is found following 3,4-dihydroxyphenylalanine ( l-dopa ) administration or an intraventricular injection of free dopamine did not result in da sulfate formation , despite the presence of phenolsulfotransferase activity in various regions of the brain and the high affinity of da for this enzyme .
C0013023
dihydroxyphenylalanine
C0023570
l-dopa