Monoamine transporter inhibitors and norepinephrine reduce dopamine-dependent iron toxicity in cells derived from the substantia nigra.
The role of dopamine in iron uptake into catecholaminergic neurons, and dopamine oxidation to aminochrome and its one-electron reduction in iron-mediated neurotoxicity, was studied in RCSN-3 cells, which express both tyrosine hydroxylase and monoamine transporters. The mean +/- SD uptake of 100 microm 59FeCl3 in RCSN-3 cells was 25 +/- 4 pmol per min per mg, which increased to 28 +/- 8 pmol per min per mg when complexed with dopamine (Fe(III)-dopamine). This uptake was inhibited by 2 microm nomifensine (43%p < 0.05), 100 microm imipramine (62%p < 0.01), 30 microm reboxetine (71%p < 0.01) and 2 mm dopamine (84%p < 0.01). The uptake of 59Fe-dopamine complex was Na+, Cl- and temperature dependent. No toxic effects in RCSN-3 cells were observed when the cells were incubated with 100 microm FeCl3 alone or complexed with dopamine. However, 100 microm Fe(III)-dopamine in the presence of 100 microm dicoumarol, an inhibitor of DT-diaphorase, induced toxicity (44% cell death; p < 0.001), which was inhibited by 2 microm nomifensine, 30 microm reboxetine and 2 mm norepinephrine. The neuroprotective action of norepinephrine can be explained by (1) its ability to form complexes with Fe3+, (2) the uptake of Fe-norepinephrine complex via the norepinephrine transporter and (3) lack of toxicity of the Fe-norepinephrine complex even when DT-diaphorase is inhibited. These results support the proposed neuroprotective role of DT-diaphorase and norepinephrine.
Paris
Irmgard
I
Molecular and Clinical Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, Santiago, Chile.
Martinez-Alvarado
Pedro
P
Perez-Pastene
Carolina
C
Vieira
Marcelo N N
MN
Olea-Azar
Claudio
C
Raisman-Vozari
Rita
R
Cardenas
Sergio
S
Graumann
Rebeca
R
Caviedes
Pablo
P
Segura-Aguilar
Juan
J
D018759:Adrenergic Uptake Inhibitors / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D050482:Catecholamine Plasma Membrane Transport Proteins; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002712:Chlorides / Q000378:metabolism; D001728:Dicumarol / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005290:Ferric Compounds / Q000378:metabolism / Q000494:pharmacology; D005455:Fluorescent Antibody Technique / Q000379:methods; D007099:Imipramine / Q000494:pharmacology; D045563:Indolequinones / Q000494:pharmacology; D007501:Iron / Q000633:toxicity*; D007503:Iron Isotopes / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009627:Nomifensine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology*; D050484:Norepinephrine Plasma Membrane Transport Proteins; D051381:Rats; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D000077593:Reboxetine; D050486:Serotonin Plasma Membrane Transport Proteins; D012964:Sodium / Q000378:metabolism; D013378:Substantia Nigra / Q000166:cytology*; D027981:Symporters / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D018759:Adrenergic Uptake Inhibitors; D050482:Catecholamine Plasma Membrane Transport Proteins; D002712:Chlorides; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D004791:Enzyme Inhibitors; D005290:Ferric Compounds; D045563:Indolequinones; D007503:Iron Isotopes; D008562:Membrane Glycoproteins; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins; D009025:Morpholines; D009419:Nerve Tissue Proteins; D050484:Norepinephrine Plasma Membrane Transport Proteins; D050486:Serotonin Plasma Membrane Transport Proteins; C493212:Slc22a1 protein, rat; C493226:Slc6a2 protein, rat; C493232:Slc6a4 protein, rat; D027981:Symporters; D017392:Thiobarbituric Acid Reactive Substances; D009627:Nomifensine; C091584:aminochrome 1; D001728:Dicumarol; D000077593:Reboxetine; D012964:Sodium; D007501:Iron; D014446:Tyrosine 3-Monooxygenase; D007099:Imipramine; D004298:Dopamine; D009638:Norepinephrine