Neuronal toxicity. Microglia plated on transwell membranes were transferred to wells containing primary neurons. After 24 h, the microglia were treated for a further 24 h with fresh media (none), LPS 1 μg/ml, MCP-1 50 ng/ml or a combination of LPS and MCP-1 at the indicated concentrations. After treatment, inserts were removed and cell viability was assessed by measurement of LDH in the neuronal media. Inserts without microglia were treated with LPS (LPSn) under the same conditions as those described above for microglia. Data are expressed as percentage of control values (set to 100%); ***p < 0.0001 versus control. Data are expressed as mean ± SE for n = 12 replicates per group.