Fig. 1

Effects of PKR deficiency on E. coli-induced sickness. WT and PKR−/− mice were subcutaneously challenged by E. coli or PBS, and sickness responses were monitored for the next 120 h. Infection of E. coli led to similar decreases in food consumption (a) and rotarod test performance (b) in WT and PKR−/− mice. *p < 0.05, ***p < 0.001, WT E. coli versus WT PBS; +p < 0.05, +++p < 0.001, PKR E. coli versus PKR PBS; n = 8 per group. However, E. coli suppressed burrowing in PKR−/− mice but not in WT mice (c). **p < 0.01, ***p < 0.001, PKR−/− E. coli versus PKR−/− PBS, n = 8 per group. Furthermore, at 120 h post-injection, E. coli downregulated open field (d) and object investigation (e) activities in PKR−/− mice but not in WT mice. *p < 0.05, ***p < 0.001; n = 13–16 per group. Likewise, E. coli decreased social interaction in PKR−/− mice but not in WT mice at 120 h (f). ***p < 0.001, empty cage versus social cage of the same experimental group; #p < 0.05, ##p < 0.01, ###p < 0.001 versus interaction with the social cage of the PKR−/− E. coli group; n = 12–15 per group