Cadmium-Induced Toxicity in Rat Primary Mid-brain Neuroglia Cultures: Role of Oxidative Stress from Microglia

• Published in: Toxicological sciences 2007-08, Vol.98 (2), p.488-494
• Main Authors: Yang, Zhengqin, Yang, Sufen, Qian, Steven Y., Hong, Jau-Shyong, Kadiiska, Maria B., Tennant, Raymond W., Waalkes, Michael P., Liu, Jie
• Format: Article
• Language: English
• Subjects: Animals; cadmium; Cadmium - toxicity; Cation Transport Proteins - genetics; Cells, Cultured; Dopamine - metabolism; gene expression; Gene Expression - drug effects; Glutathione S-Transferase pi - genetics; Heme Oxygenase-1 - genetics; Mesencephalon - cytology; Metallothionein - genetics; Neuroglia - drug effects; Neuroglia - metabolism; neuron-glia cultures; neurotoxicity; NF-kappa B - metabolism; NF-κB and AP-1; Oxidative Stress; Rats; Rats, Inbred F344; Reactive Oxygen Species - metabolism; Transcription Factor AP-1 - metabolism
• ISSN: 1096-6080; 1096-0929
• DOI: 10.1093/toxsci/kfm106

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 IC50 of 2.5μM 24 h after exposure. 3H-dopamine uptake into neuron-glia cultures was decreased 7 days after Cd exposure, with IC50 of 0.9μM, 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.