Production of trophic factors. Microglia were incubated for 24 h with fresh media (control), LPS 1 μg/ml, MCP-1 50 ng/ml or a combination of LPS and MCP-1 at the indicated concentrations. RNA was isolated and bFGF (A) and IGF-I (B) mRNA levels determined by RT-PCR. Data are expressed as percentage of control values (set to 100%); ***p < 0.0001 versus control. Data are expressed as mean ± SE for n = 6 replicates per group.