Possible Interaction: 5-Hydroxytryptophan and Dopamine

“Exposure to dopamine (10 microM) or L-DOPA (100 microM) markedly diminished the forskolin-stimulated release of melatonin, as well as the production of 5-hydroxytryptophan and serotonin.”

“α-Methyl- m -tyrosine, α-methyl-5-hydroxytryptophan , and α-methyl-2,5-dopa were found to be potent inhibitors in vivo of the conversion of dopa to urinary dopamine.”

“It is suggested that administration of 5‐HTP and L‐DOPA at specific time interval and variation in pineal functions that modulate reproductive responses also alter the circadian pattern (acrophase and amplitude) of hypothalamic serotonin and dopamine , maintaining a specific phase relation between these cycles and breeding status.”

“In the substantia nigra, carbidopa + 5-HTP treatment increased the 3-MT accumulation by 26% and decreased the DA concentration to 67% of controls, tentatively suggesting a 5-HTP-induced displacement of nigral DA.”

“The administration of 5-hydroxy-l-tryptophan (5-HTP) induced a decrease of hypothalamic concentration of noradrenaline and dopamine at both ages.”

“The backward walking induced by L-5HTP was completely inhibited by 5-HT and dopamine (DA) receptor blockers, but was not inhibited by alpha- or beta-adrenergic blocker, antihistamine or anticholinergic drug.”

“Intraperitoneal injection of dopa or 5-hydroxytryptophan (5-HTP) to rats causes a marked increase in the concentration of dopamine and 5-hydroxytryptamine (5-HT) in the gastric mucosa, and the amines are located to an enterochromaffin-like cell system in the pyloric part of the gastric mucosa (8).”