Possible Interaction: Dihydroxyphenylalanine and Tyrosine

“It has been known for half a century that DOPA is a co-factor in the oxidation of tyrosine and addition of a small amount of catechol reduces the length of the lag period.”

“ L‐Dopa competes with tyrosine as a substrate in protein synthesis in vitro.”

“Oral intake of tyrosine enhanced the tyrosine, DOPA and dopamine levels in the brain, and activated Amddc expression in the brain, suggesting that tyrosine intake can increase both substrates and enzyme for dopamine biosynthesis.”

“ Tyrosine depletion significantly lowered DOPA levels in the NSD-1015 treated group and lowered DOPAC but not dopamine or noradrenaline levels in the group not exposed to NSD-1015.”

“Addition of L-tyrosine to the medium led to increases in the level of synthesis and release of L-DOPA in the mediobasal hypothalamus and substantia nigra.”

“ TYR suppressed DOPA synthesis from (3)H-PHE at concentrations lower than that observed for a similar inhibition by PHE of DOPA synthesis from (3)H-TYR.”

“Release of 3,4‐dihydroxyphenylalanine was calcium and frequency dependent, inhibited by α‐m‐L‐p‐tyrosine (an inhibitor of tyrosine hydroxylase) and augmented by 3‐hydroxybenzylhydrazine (an inhibitor of aromatic amino acid decarboxylase).”

“Ascorbic acid acts as an effective reductant for the hydroxylation of tyrosine by tyrosinase, while 3,4-dihydroxyphenylalanine is both an effective reductant and counteracts the inhibition by tyrosine at pH 6.8.”

“In both normal and diabetic rats exposed to light, tyrosine injection raised retinal tyrosine concentrations and stimulated dopa accumulation.”

“The possibility that the pharmacological effects of m-tyrosine can at least partly be explained by dopamine generation from DOPA is discussed.”