Role of monoamine neural systems in L-dihydroxyphenylalanine-stimulated activity.
The potentiation of the stimulatory response to L-dihydroxyphenylalanine (L-dopa) in 6-hydroxydopamine-treated rats given a peripheral decarboxylase inhibitor occurred only after treatments that destroyed dopamine-containing fibers, Destruction of serotonin- or norepinephrine-containing fibers did not potentiate the action of L-dopa. Furthermore, other data indicated thatL-dopa-induced activity could not be attributed to release of serotonin or to the formation of norepinephrine. That the L-dopa must be converted to catecholamines was demonstrated by antagonism of the activity responses to L-dopa with inhibition of decarboxylases in brain. After destruction of serotonin-containing fibers with 5,7-dihydroxytryptamine, L-dopa-induced activity in 6-hydroxydopamine-treated rats was significantly reduced, as was the accumulation of dopamine formed from L-dopa. These latter data provide direct evidence that serotonergic fibers contribute to the accumulation of dopamine in brain after L-dopa administration to 6-hydroxydopamine-treated rats.
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001679:Biogenic Amines / Q000502:physiology*; D001921:Brain / Q000378:metabolism; D002262:Carboxy-Lyases / Q000037:antagonists & inhibitors; D002395:Catecholamines / Q000502:physiology; D004298:Dopamine / Q000502:physiology; D004299:Dopamine beta-Hydroxylase / Q000037:antagonists & inhibitors; D006892:Hydroxydopamines / Q000494:pharmacology; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D012701:Serotonin / Q000502:physiology; D014365:Tryptophan Hydroxylase / Q000037:antagonists & inhibitors
D001679:Biogenic Amines; D002395:Catecholamines; D006892:Hydroxydopamines; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D007980:Levodopa; D014365:Tryptophan Hydroxylase; D004299:Dopamine beta-Hydroxylase; D002262:Carboxy-Lyases; D001058:Apomorphine; D004298:Dopamine