Effects of uracil nucleotides in cell death in lipopolysaccharide (LPS) cultures. (A) Necrotic cell death was evaluated by measuring the release of lactate dehydrogenase (LDH) and apoptotic cell death was evaluated by the TUNEL assay, after incubation with uracil nucleotides or solvent for 48 h. LDH activity was measured in the culture medium and in the culture extracts and the fraction released is represented in percentage of total LDH. The number of apoptotic cells was expressed as percentage of the total number of cells counted. Values are means ± SEM from four to seven experiments. *P <0.05, significant differences from respective control (solvent). (B) Cellular localization of apoptotic nuclei, obtained with the Hoechst 33258 staining in LPS cultures. Astrocytes were labeled with rabbit anti-GFAP (TRITC, red), microglia with mouse anti-CD11b (Alexa Fluor 488, green) and cell nuclei with Hoechst 33258 (blue). LPS cultures were incubated with solvent or UDP for 48 h. Shrunken nuclei with a bright fluorescence appearance, characteristic of apoptotic nuclei are clearly coincident with astrocytes (white arrows), but not with microglia. Scale bar = 20 μM.