Possible Interaction: Dopamine and Ascorbate

“Although extracellular ascorbate appears to modulate the synaptic action of dopamine , the mechanisms underlying this effect are unclear.”

“In fact, by facilitating glutamate release, ascorbate may indirectly oppose the action of dopamine , though the nature of the neostriatal dopaminergic-glutamatergic interaction is far from settled.”

“Treatment with 100 μM dopamine acutely increased cellular superoxide generation, which was prevented … the latter was present at concentrations under 1 mM. These results show that ascorbate … dopamine by neuronal cells that it does so at physiologic intracellular concentrations … protects cells from superoxide and by providing electrons to DβH.”

“Conversely, the CuAbeta-catalyzed oxidation reaction of dopamine is inhibited by bio-available reducing agents such as ascorbate (competitive K(ic)=66 microM) and glutathione (non-competitive, K(inc)=53 microM).”

“The linear calibration range for DA in the presence of 0.3 mM AA is 50 nM to 10 microM, with a correlation coefficient of 0.998 and a detection limit of 10 nM using 45-s accumulation.”

“Overall, DA plays pivotal roles in regulating ascorbate homeostasis through an unanticipated signaling pathway involving D1R/adenylyl cyclase/cAMP/EPAC2, thereby suggesting that vitamin C might fine-tune dopaminergic neurotransmission in the retina.”

“Damage to mesencephalic dopamine and GABA cell populations were significantly attenuated when carried out in the presence of ascorbate or SOD, indicative of a free radical-mediated contribution to toxicity.”

“The effects of ascorbate , which is known to modulate dopamine neurotransmission, on the extracellular level of DOPAC in the nucleus accumbens of naive rats and of rats treated acutely with morphine were studied by using in vivo microdialysis and high performance liquid chromatography with electrochemical detection (HPLC-ECD).”

“Ascorbate has complicated concentration-dependent effects on IK(V) of Mb cells in vitro that were mediated by D1 dopamine receptors, suggesting that dopamine and ascorbate may be involved reciprocally in modulating IK(V), with consequences on the transmission of rod signals to the inner retina.”

“ Ascorbate , often used as an antioxidant in neural studies, may also serve as a neuromodulator in the vertebrate central nervous system (CNS), in that it modulates the synaptic actions of glutamate and dopamine.”

“The dopamine dependent inhibition was enhanced by adding soluble dopamine beta-monooxygenase (DBM, 0.2 U/ml) and completely prevented by ascorbate (1 mM), dithiothreitol (2 mM) and approximately 80% by the DBM inhibitor fusaric acid (10 microM).”