The drug-action atlas

Enter through a molecule, a synapse, or a brain circuit. Change the conditions and trace what happens next.

All learning models

Explore the system

Neurotransmitter systems

Choose a messenger. Follow its precursor, synthesis, release, receptor families, and clearance as one connected system.

Neurotransmitter systems

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Dopamine (DA)

Dietary tyrosine → L-DOPA

Movement, motivation, reinforcement, and cognition

Mechanism and exceptions

Rate-limiting step / synthesis constraint: Tyrosine hydroxylase
Source neurons / location: Substantia nigra; ventral tegmental area; hypothalamic neurons
Drug mechanism: DAT inhibition leaves dopamine outside longer; releasers drive outward flow; MAO inhibition reduces intracellular breakdown.

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Explore the system

Dietary tyrosine → L-DOPA → Tyrosine hydroxylase → L-DOPA; aromatic amino-acid decarboxylase → dopamine → D1-like and D2-like: G protein-coupled → Monoamine oxidase (MAO); catechol-O-methyltransferase (COMT)

Animate the diagram

On a small screen, pan the diagram or increase zoom. Named controls provide the same exploration by keyboard.

Sources and model limits

Original schematic. Positions show relationships; structures and concentrations are not to scale.

Julien's Primer of Drug Action · 15 · 2 · Neurotransmitter systems · PDF 26, 27, 28, 29, 30, 31 · 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18
Professor deck 3 · Additional messengers and receptor exceptions · PDF 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44

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The drug-action atlas

Enter through a molecule, a synapse, or a brain circuit. Change the conditions and trace what happens next.

All learning models

Explore the system

Neurotransmitter systems

Choose a messenger. Follow its precursor, synthesis, release, receptor families, and clearance as one connected system.

Neurotransmitter systems

Diagram zoom

Dopamine (DA)

Dietary tyrosine → L-DOPA

Movement, motivation, reinforcement, and cognition

Mechanism and exceptions

Rate-limiting step / synthesis constraint: Tyrosine hydroxylase
Source neurons / location: Substantia nigra; ventral tegmental area; hypothalamic neurons
Drug mechanism: DAT inhibition leaves dopamine outside longer; releasers drive outward flow; MAO inhibition reduces intracellular breakdown.

Diagram zoom

Explore the system

Animate the diagram

On a small screen, pan the diagram or increase zoom. Named controls provide the same exploration by keyboard.

Sources and model limits

Original schematic. Positions show relationships; structures and concentrations are not to scale.

Julien's Primer of Drug Action · 15 · 2 · Neurotransmitter systems · PDF 26, 27, 28, 29, 30, 31 · 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18
Professor deck 3 · Additional messengers and receptor exceptions · PDF 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44