Chronic stimulation of D1 dopamine receptors in human SK-N-MC neuroblastoma cells induces nitric-oxide synthase activation and cytotoxicity.
Elevated synaptic levels of dopamine may induce striatal neurodegeneration in l-DOPA-unresponsive parkinsonism subtype of multiple system atrophy (MSA-P subtype), multiple system atrophy, and methamphetamine addiction. We examined the participation of dopamine and D1 dopamine receptors in the genesis of postsynaptic neurodegeneration. Chronic treatment of human SK-N-MC neuroblastoma cells with dopamine or H2O2 increased NO production and accelerated cytotoxicity, as indexed by enhanced nitrite levels and cell death. The antioxidant sodium metabisulfite or SCH 23390, a D1 dopamine receptor-selective antagonist, partially blocked dopamine effects but together ablated dopamine-mediated cytotoxicity, indicating the participation of both autoxidation and D1 receptor stimulation. Direct activation of D1 dopamine receptors with SKF R-38393 caused cytotoxicity, which was refractory to sodium metabisulfite. Dopamine and SKF R-38393 induced overexpression of the nitric-oxide synthase (NOS) isoforms neuronal NOS, inducible NOS (iNOS), and endothelial NOS in a protein kinase A-dependent manner. Functional studies showed that approximately 60% of total NOS activity was due to activation of iNOS. The NOS inhibitor N(G)-nitro-l-arginine methyl ester and genistein, wortmannin, or NF-kappaB SN50, inhibitors of protein tyrosine kinases phosphatidylinositol 3-kinase and NF-kappaB, respectively, reduced nitrite production by dopamine and SKF R-38393 but were less effective in attenuating H2O2-mediated effects. In rat striatal neurons, dopamine and SKF R-38393, but not H2O2, accelerated cell death through increased expression of neuronal NOS and iNOS but not endothelial NOS. These data demonstrate a novel pathway of dopamine-mediated postsynaptic oxidative stress and cell death through direct activation of NOS enzymes by D1 dopamine receptors and its associated signaling pathways.
Chen
Jun
J
Department of Pediatrics, Georgetown University, Washington, DC 20007, USA.
Wersinger
Christophe
C
Sidhu
Anita
A
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D016923:Cell Death; D002470:Cell Survival; D002478:Cells, Cultured; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000201:enzymology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005609:Free Radicals; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D016328:NF-kappa B / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000201:enzymology / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D018384:Oxidative Stress; D010957:Plasmids / Q000378:metabolism; D051381:Rats; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D000975:Antioxidants; D001552:Benzazepines; D004791:Enzyme Inhibitors; D005609:Free Radicals; D016328:NF-kappa B; D009573:Nitrites; D017447:Receptors, Dopamine D1; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D006861:Hydrogen Peroxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D019331:NG-Nitroarginine Methyl Ester; D004298:Dopamine