Dopamine: stimulation-induced release from central neurons.
Dopamine, synthesized in rat brain slices from labeled L-tyrosine or L-dopa, can be released by electrical stimulation of a type known to induce neuronal depolarization. Pretreatment of the animals with 6-hydroxydopamine, which destroys central catecholamine-containing nerve terminals, substantially reduced the release of dopamine synthesized from [(14)C]tyrosine or from a low concentration of [(3)H]dopa, whereas the release of dopamine formed from a high concentration of [(3)H]dopa remained essentially unchanged. The observations that at high concentrations L-dopa may enter noncatecholaminergic cells, undergo decarboxylation to dopamine, and subsequently be liberated in response to depolarization suggest that dopamine may act as a substitute central transmitter, possibly in serotonergic neurons. This mechanism may contribute to L-dopa's clinical effects in parkinsonian patients.
D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D003864:Depression, Chemical; D004295:Dihydroxyphenylalanine / Q000378:metabolism / Q000627:therapeutic use; D004296:Dopa Decarboxylase / Q000378:metabolism; D004298:Dopamine / Q000096:biosynthesis / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010300:Parkinson Disease / Q000188:drug therapy / Q000201:enzymology; D010627:Phenethylamines / Q000494:pharmacology; D051381:Rats; D014316:Tritium; D014443:Tyrosine / Q000378:metabolism
D002247:Carbon Isotopes; D010627:Phenethylamines; D014316:Tritium; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D004296:Dopa Decarboxylase; D004298:Dopamine