Rat brain endothelial cells are a target of manganese toxicity.
Manganese (Mn) is an essential trace metal; however, exposure to high Mn levels can result in neurodegenerative changes resembling Parkinson's disease (PD). Information on Mn's effects on endothelial cells of the blood-brain barrier (BBB) is lacking. Accordingly, we tested the hypothesis that BBB endothelial cells are a primary target for Mn-induced neurotoxicity. The studies were conducted in an in vitro BBB model of immortalized rat brain endothelial (RBE4) cells. ROS production was determined by F(2)-isoprostane (F(2)-IsoPs) measurement. The relationship between Mn toxicity and redox status was investigated upon intracellular glutathione (GSH) depletion with diethylmaleate (DEM) or L-buthionine sulfoximine (BSO). Mn exposure (200 or 800 microM MnCl(2) or MnSO(4)) for 4 or 24h led to significant decrease in cell viability vs. controls. DEM or BSO pre-treatment led to further enhancement in cytotoxicity vs. exposure to Mn alone, with more pronounced cell death after 24-h DEM pre-treatment. F(2)-IsoPs levels in cells exposed to MnCl(2) (200 or 800 microM) were significantly increased after 4h and remained elevated 24h after exposure compared with controls. Consistent with the effects on cell viability and F(2)-IsoPs, treatment with MnCl(2) (200 or 800 microM) was also associated with a significant decrease in membrane potential. This effect was more pronounced in cells exposed to DEM plus MnCl(2) vs. cells exposed to Mn alone. We conclude that Mn induces direct injury to mitochondria in RBE4 cells. The ensuing impairment in energy metabolism and redox status may modify the restrictive properties of the BBB compromising its function.
dos Santos
Ana Paula Marreilha
AP
i-Med-UL, Faculdade de Farmácia, Universidade de Lisboa, Lisbon, Portugal. apsantos@ff.ul.pt
Milatovic
Dejan
D
Au
Catherine
C
Yin
Zhaobao
Z
Batoreu
Maria Camila C
MC
Aschner
Michael
M
D000818:Animals; D001812:Blood-Brain Barrier / Q000166:cytology*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D042783:Endothelial Cells / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D008298:Maleates / Q000494:pharmacology; D008345:Manganese / Q000633:toxicity*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors; D014131:Trace Elements / Q000633:toxicity*
D004791:Enzyme Inhibitors; D008298:Maleates; D017382:Reactive Oxygen Species; D014131:Trace Elements; D008345:Manganese; D019328:Buthionine Sulfoximine; C014476:diethyl maleate; D005978:Glutathione