Cadmium-induced toxicity in rat primary mid-brain neuroglia cultures: role of oxidative stress from microglia.
This study examined the role of oxidative stress in neurotoxic effects of cadmium chloride (Cd) in rat primary mid-brain neuron-glia cultures. Cd accumulated in neuron-glia cultures and produced cytotoxicity in a dose-dependent manner, with IC(50) of 2.5microM 24 h after exposure. (3)H-dopamine uptake into neuron-glia cultures was decreased 7 days after Cd exposure, with IC(50) of 0.9microM, indicative of the sensitivity of dopaminergic neurons to Cd toxicity. To investigate the role of microglia in Cd-induced toxicity to neurons, microglia-enriched cultures were prepared. Cd significantly increased intracellular reactive oxygen species production in microglia-enriched cultures, as evidenced by threefold increases in 2',7'-dichlorofluorescein signals. Using 5,5-dimethyl-1-pyrroline N-oxide as a spin-trapping agent, Cd increased electron spin resonance signals by 3.5-fold in microglia-enriched cultures. Cd-induced oxidative stress to microglia-enriched cultures was further evidenced by activation of redox-sensitive transcription factor nuclear factor kappa B and activator protein-1 (AP-1), and the increased expression of oxidative stress-related genes, such as metallothionein, heme oxygenase-1, glutathione S-transferase pi, and metal transport protein-1, as determined by gel-shift assays and real-time reverse transcription-PCR, respectively, in microglia-enriched cultures. In conclusion, Cd is toxic to neuron-glia cultures, and the oxidative stress from microglia may play important roles in Cd-induced damage to dopaminergic neurons.
Yang
Zhengqin
Z
Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Yang
Sufen
S
Qian
Steven Y
SY
Hong
Jau-Shyong
JS
Kadiiska
Maria B
MB
Tennant
Raymond W
RW
Waalkes
Michael P
MP
Liu
Jie
J
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D027682:Cation Transport Proteins / Q000235:genetics; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D051549:Glutathione S-Transferase pi / Q000235:genetics; D051547:Heme Oxygenase-1 / Q000235:genetics; D008636:Mesencephalon / Q000166:cytology; D008668:Metallothionein / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats; D011916:Rats, Inbred F344; D017382:Reactive Oxygen Species / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D000098742:Ferroportin
D027682:Cation Transport Proteins; C491055:Mt2A protein, rat; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D000098742:Ferroportin; D002104:Cadmium; D008668:Metallothionein; D051547:Heme Oxygenase-1; D051549:Glutathione S-Transferase pi; D004298:Dopamine