Figure 7

(A) Production of bioactive TNF-α by serum-deprived astrocytes as they re-enter cell cycle following LPS stimulation. Newborn rat astrocytes were rendered into G₀ phase by serum deprivation and then allowed to re-enter the cell cycle via serum up-shift in the presence of graded concentrations of LPS. After a 24-h incubation, cell-free medium was collected to measure bioactive TNFα production and the rate of DNA synthesis using the WEHI and ³H-thymidine incorporation assays, respectively (n = 7–9 results show an average of three experiments). (B) LPS-stimulated cell cycle re-entry in astrocytes is TNF-α-dependent. Newborn astrocytes were rendered into G₀ phase by serum deprivation and then allowed to re-enter the cell cycle via serum up-shift in the presence of freshly prepared LPS (100 pg/ml) with or without anti-TNF-α antibodies (10 U/mL). The ³H-thymidine incorporation assay was performed to measure rate of DNA synthesis. WT vs. LPS treatment: ***p < 0.05; **p < 0.001; *p < 0.0001. LPS treatment group vs. LPS + anti-TNF-α antibodies: ^!p < 0.001; ^!!p < 0.01; ^!!!p < 0.05 (n = 7–9 results show an average of three experiments).