Dopamine !

Dopamine is a catecholamine neurotransmitter for movement, reward and prolactin control, and the precursor of norepinephrine.

Updated 2026-11-01

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Key facts

Made from L-DOPA by aromatic L-amino acid decarboxylase (B6).
Main pathways: nigrostriatal (movement), mesolimbic (reward), tuberoinfundibular (inhibits prolactin).
Dopamine β-hydroxylase (copper, vitamin C) turns it into norepinephrine inside vesicles.
MAO and COMT break it down to homovanillic acid (HVA).

A catechol ring with a two-carbon ethylamine side chain (no carboxyl, unlike L-DOPA).

Loss of nigrostriatal dopamine causes the motor signs of Parkinson disease.
Dopamine-blocking antipsychotics can cause parkinsonism and raise prolactin.
Given intravenously it acts on dopamine, β₁ and α₁ receptors depending on the dose and is used in shock.

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Which enzyme converts dopamine to norepinephrine, and what does it need?

Dopamine β-hydroxylase, which needs copper, vitamin C and O₂.

Why do dopamine-blocking drugs raise prolactin?

Hypothalamic dopamine normally inhibits prolactin release from the pituitary; blocking its receptors removes that brake.

What is the main breakdown product of dopamine?

Homovanillic acid (HVA), made by MAO and COMT.

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: Dopamine (CID 681) (PubChem, NCBI, 2026) · Public domain; Aromatic l-amino acid decarboxylase deficiency: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.