Lithium enhances LPS-tolerance. (A) Mouse primary astrocytes were pretreated with 100 ng/mL LPS with or without the GSK3 inhibitor 20 mM LiCl for 24 h, or (B) LiCl was added for either 24 h or for the last 1 h of the first stimulation with LPS, cells were washed and restimulated with 10 ng/mL LPS for 24 h (mean ± SEM; n=3; *p<0.05, ANOVA). (C) Mouse primary astrocytes were treated as in (B) and were immunoblotted for phosphoSer21GSK3α, phosphoSer9GSK3β, and total GSK3α/β (representative of 3 independent experiments). (D) After treatments as indicated, immunoblotting was used to measure the total level and serine-phosphorylation of GSK3α and GSK3β in mouse primary microglia (3.75 µg protein) and mouse primary astrocytes (1.5 µg protein). Results are representative of three independent measurements. The level of GSK3β in astrocytes was 362 ± 40% (n=3) the level in microglia in the 0/0 treated samples (taking into account the different amounts of protein loaded for each cell type, which was necessary to obtain accurate immunoblots of GSK3β in each cell type measured on the same gel).