Possible Interaction: Dopamine and Tryptophan

“Thus, for example, brain levels of tryptophan , tyrosine, or choline can control the rates at which neurons synthesize serotonin, dopamine , or acetylcholine, respectively.”

“Neuronal cells treated with single AAAs in vitro further demonstrated that tryptophan and tyrosine enhanced 5‐HT and dopamine synthesis, respectively, and promoted BDNF expression partly through the 5‐HT1A/DRD1‐CREB pathway.”

“Feeding the fish with moderate Trp doses also evoked a general increase in DA and 5-HT-ergic activity, suggesting that these neural circuits within the NLT and Dl may be indirectly involved in regulating the acute stress response.”

“SH rats, treated with the higher dose of tryptophan, also significantly reduced their urinary outputs of epinephrine and norepinephrine compared with SH controls, while both doses of tryptophan increased urinary outputs of dopamine significantly above that of SH controls.”

“On the other hand, the tranquillizing effect of L-tryptophan correlates not only to the increased level of 5-HT but also to an accelerated catabolism of dopamine.”

“Intravenous injection of tryptophan in the dog can increase concentrations of homovanillic acid, the major metabolite of dopamine , in the cerebrospinal fluid and decrease levels of dopamine in the basal ganglia13.”

“We have shown that dopamine and other catechols effectively inhibit serotonin synthesis from tryptophan in slices obtained from rat's brain.”

“demonstrating that there was an interaction between the cerebral metabolism of tryptophan and dopamine.”