The present study examined the functional characteristics of the inward and outward L-[14C]DOPA and L-[14C]leucine transporters in LLC-PK1 cells. Uptake was initiated by the addition of Hanks' medium with a given concentration of L-[14C]DOPA or L-[14C]leucine. Saturation experiments were performed in cells incubated for 6 min with 0.25 microM concentration of the substrates in the absence and t...

L-dopa is used to treat the motor symptoms associated with Parkinson's disease, a neurodegenerative movement disorder characterized by a loss of dopamine neurons. L-dopa is the precursor to dopamine and crosses the blood-brain barrier to increase dopamine neurotransmission. This review will focus on the findings that dopamine produced from L-dopa is mediated in part by serotonin neurons. Direct...

The aim of the present study was to investigate the possibility that catecholaminergic pathways within the central nervous system play a role in the control of renin secretion. Plasma renin activity (PRA) was measured after intravenous administration of L-dopa with and without prior inhibition of extracerebral dopa decarboxylase by carbidopa (MK-486) in pentobarbital-anesthetized dogs in which ...

The catecholamine precursor l-dihydroxyphenylalanine (L-DOPA) is the primary therapeutic intervention for Parkinson's disease. Although short-term exposure (30 min) potentiates dopamine (DA) release by elevating quantal size, longer term exposure to L-DOPA (48 hr) promotes neurite outgrowth from midbrain DA neurons in culture. To characterize long term effects of L-DOPA, we used a pheochromocyt...

The biochemistry of mussel adhesion has inspired the design of surface primers, adhesives, coatings and gels for technological applications. These mussel-inspired systems often focus on incorporating the amino acid 3,4-dihydroxyphenyl-L-alanine (Dopa) or a catecholic analog into a polymer. Unfortunately, effective use of Dopa is compromised by its susceptibility to auto-oxidation at neutral pH....

Parkinson’s disease is one of the most common progressive neurodegenerative disorder. It is characterized by the depletion of dopamine in the dopaminergic neurons of the striatum of the brain. Pharmacological treatment involves the administration of a dopamine precursor, levodopa (L-Dopa), which crosses the blood-brain barrier and replaces the loss of dopamine in the brain. One of the main draw...

in this study, undoped zno and doped with fe and mn nanostructures were synthesized by hydrothermal method. the morphology of nanostructures was characterized by scanning electron microscope. the electrochemical response of the carbon paste electrode modified with nanoparticles of zno and also zno doped with fe and mn toward levodopa (l-dopa) was studied. studies of cyclic voltammetry using pro...

gamma-Glutamyl L-dopa, a renal pro-drug for dopamine, was administered to rats before and after injection of glycerol, and to a control group which received water in place of glycerol. A third group of rats was given glycerol but no gamma-glutamyl L-dopa. The plasma creatinine in rats given gamma-glutamyl L-dopa and glycerol was significantly lower than in rats receiving glycerol alone. The fal...

Targeted deletion or selective pharmacological inhibition of α(2C)-adrenoceptors in mice results in increased brain tissue levels of dopamine and its precursor l-3,4-dihydroxyphenylalanine (l-DOPA), without significant changes in l-DOPA synthesis. l-DOPA uptake is considered the rate-limiting step in dopamine synthesis in the kidney. Since α(2C)-adrenoceptors may influence the transport of l-DO...

The amino acid L-3,4-dihydroxyphenylalanine (L-dopa) is prescribed for conditions where increased central and/or peripheral dopamine synthesis is desired. Its administration can establish dopamine concentrations higher than can be achieved from an optimal diet. Specific indications include Parkinson's disease and restless leg syndrome. The interaction between serotonin and dopamine exists in on...