Figure 6

LPS triggers microglial N9 proliferation in a manner dependent on extracellular BDNF and A _2A R activation. Cells were exposed to LPS (100 ng/mL) for 6 hours in the presence of BrdU for the last 2 hours. Proliferation was quantified as the number of BrdU-labeled nuclei (red) and expressed as a percentage of the total number of DAPI-labeled nuclei (blue). (A) Representative images illustrating the ability of LPS to enhance N9 microglial cell proliferation, an effect prevented both by an anti-BDNF antibody (10 μg/mL) and by the selective A_2AR antagonist, SCH58261 (50 nM). Average quantitative analysis shows that anti-BDNF antibody (B) or SCH58261 (C) prevents LPS-induced proliferation. (D) Representative images illustrating the ability of added BDNF (20 ng/mL) to enhance N9 microglial cells proliferation, an effect prevented both by the selective A_2AR antagonist, SCH58261 (50 nM) and by adenosine deaminase (ADA, 1 U/mL). Average quantitative analysis shows the ability of SCH58261 (50 nM) and ADA (1 U/mL) to prevent BDNF effects (E). Results are expressed as mean ± SEM of n (as indicated in each bar) independent experiments (** P < 0.01, compared with non-treated cells; ··· P < 0.001, ·· P < 0.01, compared with LPS-treated cells; ·· P < 0.01, · P < 0.05 compared with BDNF-treated cells using the Newman–Keuls multiple comparison test) and 100% represents proliferation of cells that were not exposed to LPS. A_2AR, A_2A receptor; ADA, adenosine deaminase; BDNF, brain-derived neurotrophic factor; LPS, lipopolysaccharide; SEM, standard error of the mean.