ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
The aim of this study was to investigate the effect of l-DOPA and glia-conditioned medium (GCM) on cell viability, tyrosine hydroxylase (TH) expression, dopamine (DA) metabolism and glutathione (GSH) levels of NB69 cells. l-DOPA (200 µm) induced differentiation of NB69 cells of more than 4 weeks in vitro, as shown by phase-contrast microscopy and TH immunocytochemistry, and decreased replication, as shown by 5-bromodeoxyuridine immunostaining. l-DOPA did not increase the number of necrotic or apoptotic cells, as shown by morphological features, Trypan Blue, lactate dehydrogenase activity, bis-benzimide staining and TUNEL assay. Furthermore, l-DOPA (200 µm) increased Bcl-xL protein expression. Incubation of cells with l-DOPA (50, 100, 200 µm) for 24 h resulted in an increase in TH protein levels (174, 196 and 212% versus control). Neither carbidopa, an inhibitor of l-aromatic amino acid decarboxylase enzyme, nor l-buthionine sulfoximine, which inhibits GSH synthesis, or ascorbic acid, an antioxidant, blocked the l-DOPA-induced effect on TH protein expression. l-DOPA (0, 50, 100 and 200 µm) plus GCM further increased the amount of TH protein (346, 446, 472 and 424%). l-DOPA (200 µm) increased TH protein levels to 132, 191 and 245% of controls after incubation for 24, 48 and 72 h. DA metabolism in NB69 cells was increased in cultures treated with either l-DOPA (200–300 µm) or GCM and these two agents had a synergistic effect on DA metabolism. In addition, l-DOPA (200 µm) or/and GCM-treated cells increased their GSH extracellular levels (223, 257, 300% of controls) after 48 h of treatment. The l-DOPA-induced increase of TH protein expression in NB69 cells was independent of DA production, free radicals and GSH up-regulation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.2001.00440.x
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