epinephrine (adrenaline) in the biosynthetic pathways for these neurotransmitters. [ edit ] Biosynthesis Dopamine is biosynthesized in the body (mainly by nervous tissue and the medulla of the adrenal glands ) first by the hydration of the amino acid L-tyrosine to L-DOPA via the enzyme tyrosine 3-monooxygenase, also known as tyrosine