Dihydroxyphenylacetic acid

DOPAC (dihydroxyphenylacetic acid) is a metabolite of dopamine. The dopaminergic pathway consists of the following:

> via MAO -> DOPAC -> via COMT /                                   \ Dopamine (DA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ---> homovanillic acid (HVA) \                                   /                 > via COMT -> 3-MT -> via MAO

One of the three direct products from the alteration of dopamine (DOPAC, 3-MT (3-methoxytyramine) and noradrenaline) DOPAC is an important metabolite when studying the behaviour of the dopaminergic system for multiple reasons; 3-MT is generally more difficult to assay alongside dopamine and by assessing all three metabolites (DOPAC, HVA and 3-MT) abnormalities in either COMT (catechol-O-methyl transferase) or MAO (monoamine oxidase) can be indirectly identified. This has large ramifications as COMT abnormalities are suspected in various neuropsychiatric diseases including schizophrenia.