IGF-I increases the expression of IL6, IL-1β and TNF-α and decreases the expression of TLR4 in astrocytes under basal conditions. mRNA levels of IL6 (A,B), IL-1β (C,D), TNF-α (E,F) and TLR4 (G,H) in astrocytes 24 h (A,C,E,G) or 72 h (B,D,F,H) after the addition of IGF-I (50 or 100 nM) or vehicle to the cultures. Data are presented as mean ± SEM and are expressed as percentage of control (vehicle) values. *,**,***, Significant differences (* P < 0.05; **P < 0.01; ***P < 0.001) in comparison to the values of cultures treated with vehicle only. §§, §§§, Significant differences (§§P < 0.01; §§§P < 0.001) between 50 nM and 100 nM IGF-I.