The Effect of Environmental Temperature on Lethality of Endotoxin and Its Effect on Body Temperature in Mice

摘要

Acute exposure of mice to an environmental temperature of either 5C or 37C reduced the LD50 of a crude Serratis marcescens endotoxin from a high of 2300 micrograms in mice housed at 30C to an amount less than 40 micrograms. At 15C or 32C, the LD50 was, respectively, 880 micrograms and 550 micrograms, while at 25C it was 1200 micrograms. Control animals placed at each of these temperatures were able to maintain normothermia except for those at the high and low extremes where they became slightly hyperthermic and hypothermic. Following an injection of either twice the LD50 or a dose of 1000 micrograms, the thermoregulatory ability was upset at all temperatures except 30C. Mice at temperatures below 30C became progressively more hypothermic as the environment was increasingly cold and vice versa at higher temperatures. It is believed that endotoxin sensitizes mice to heat and cold rather than these temperatures sensitizing to endotoxin. After one week of acclimatization at 5C or 37C, the LD50 of endotoxin increased, respectively, to 790 micrograms and 260 micrograms. Inducibility of the liver enzyme tryptophan pyrrolase, believed to play a role in an animal's response to endotoxin, was evaluated at each environmental temperature. Only at the extremes was it suppressed. (Author)