Epinephrine Synthesis, Adrenergic Receptors & Pharmacology
Epinephrine and Norepinephrine Synthesis
The synthesis pathway for catecholamines like norepinephrine and epinephrine is as follows:
- Phenylalanine is converted to Tyrosine.
- Tyrosine is taken into the neuron via a transporter.
- Tyrosine is converted to L-DOPA by the enzyme Tyrosine Hydroxylase. (This is the rate-limiting step in the pathway).
- L-DOPA is converted to Dopamine by the enzyme Dopa Decarboxylase.
- Dopamine is transported into a vesicle via the Vesicular Monoamine Transporter (VMAT).
- Inside the vesicle, Dopamine is converted to Norepinephrine by the enzyme Dopamine Beta-Hydroxylase.
- Synthesis may stop at Norepinephrine, depending on the cell type.
- In the adrenal medulla, Norepinephrine can be further converted to Epinephrine by the enzyme Phenylethanolamine