The effects of nicotine on lipopolysaccharide (LPS)-induced Erk1/2 and p38 mitogen-activated protein kinase (MAPK) activation in astrocytes. LPS also increased Erk1/2 and p38 MAPK phosphorylation, reflecting their activation. (A,B) Astrocytes were treated with LPS 100 ng/ml for various lengths of time as indicated. (C,D) Astrocytes were pretreated with nicotine 10 μmol/l in the absence or presence of MLA 100 nmol/l for 30 minutes and then challenged with LPS for 30 minutes. After treatment, astrocytes were harvested, and levels of phosphorylated (A,C) Erk1/2 and (B,D) p38 MAPK were analyzed. Upper panel shows densitometric analysis of the phosphorylated forms of Erk1/2 and p38 MAPK, while the lower panel shows representative blots.. Data are presented as the mean ± SEM of four independent experiments. *P < 0.05 and **P < 0.01 versus the control group; #
P < 0.05 and ##
P < 0.01 versus the LPS treatment alone group.