Effects of different serotypes of Escherichia coli lipopolysaccharides on body temperature in rats

The effects of Escherichia coli O55:B5, O127:B8, and O111:B4 serotypes' lip opolysaccharides (LPS) on body temperature were investigated in rats. LPSs were injected intraperitoneally at doses of 2, 50, and 250 mu g/kg. A multi phasic and no-dose dependent increase in rectal temperature was observed in response to E, coli O55:B5 LPS at all doses, and in response to E, coli O1 27:Bs LPS at 2 and 50 mu g/kg doses. The highest dose of the latter caused a dual change in rectal temperature, in which hypothermia preceded fever. E , coli O111:B4 LPS was either pyrogenic or hypothermic at 2 and 250 mu g/kg doses; respectively, whereas a dual response was observed when the 50 mu g /kg dose was injected. Although dual responses were observed after administ ration of all LPSs at 50 mu g/kg dose when the body temperature was recorde d by biotelemetry, the hypothermia induced by E. coli O55:B5 LPS was signif icantly smaller. These data suggest that LPSs induce dose and serotype-spec ific variable changes on body temperature in rats, This variability may be related to the structure of LPSs. The data also indicate that LPS causes hy pothermia with or without fever in rats. (C) 2000 Elsevier Science inc. All rights reserved.