<Table> <Tr> <Td> Biosynthetic pathways for catecholamines and trace amines in the human brain L - Phenylalanine L - Tyrosine L - DOPA Epinephrine Phenethylamine p - Tyramine Dopamine Norepinephrine N - Methylphenethylamine N - Methyltyramine p - Octopamine Synephrine 3 - Methoxytyramine AADC AADC AADC primary pathway PNMT PNMT PNMT PNMT AAAH AAAH brain CYP2D6 minor pathway COMT DBH DBH In humans, catecholamines and phenethylaminergic trace amines are derived from the amino acid phenylalanine . It is well established that dopamine is produced from L - tyrosine via L - DOPA; however, recent evidence has shown that CYP2D6 is expressed in the human brain and catalyzes the biosynthesis of dopamine from L - tyrosine via p - tyramine . </Td> </Tr> </Table> <Tr> <Td> Biosynthetic pathways for catecholamines and trace amines in the human brain L - Phenylalanine L - Tyrosine L - DOPA Epinephrine Phenethylamine p - Tyramine Dopamine Norepinephrine N - Methylphenethylamine N - Methyltyramine p - Octopamine Synephrine 3 - Methoxytyramine AADC AADC AADC primary pathway PNMT PNMT PNMT PNMT AAAH AAAH brain CYP2D6 minor pathway COMT DBH DBH In humans, catecholamines and phenethylaminergic trace amines are derived from the amino acid phenylalanine . It is well established that dopamine is produced from L - tyrosine via L - DOPA; however, recent evidence has shown that CYP2D6 is expressed in the human brain and catalyzes the biosynthesis of dopamine from L - tyrosine via p - tyramine . </Td> </Tr> <P> Dopamine is synthesized in a restricted set of cell types, mainly neurons and cells in the medulla of the adrenal glands . The primary and minor metabolic pathways respectively are: </P> <Dl> <Dd> Primary: L - Phenylalanine → L - Tyrosine → L - DOPA → Dopamine </Dd> <Dd> Minor: L - Phenylalanine → L - Tyrosine → p - Tyramine → Dopamine </Dd> <Dd> Minor: L - Phenylalanine → m - Tyrosine → m - Tyramine → Dopamine </Dd> </Dl>

Where does dopamine come from in the brain