Effect of Lipopolysaccharides of Gram Negative Bacilli in the Rat Litter in utero. ∗

Abstract

Summary

The LD₅₀ for rats of LS of E. typhosa was 6 mg/kg, for E. coli 10 mg/kg, S. marcescens 25 mg/kg, B. abortus Bang 60 mg/kg, and Streptococcus A more than 500 mg/kg. The ratio of lethal dosages of the LS for the litters to the single LD₅₀ for the mothers was for E. typhosa 1:3, E. coli 1:10, S. marcescens 1:12, B. abortus Bang 1:2, but could not be determined for the gram positive streptococcus. The LS of the above gram negative bacilli led to intraplacental hemorrhages and destroyed the entire litter of rats in utero in doses not lethal to the mothers when administered after implantation. The doses employed had a peak of fetus destruction between mid term and the 15th g.d. Surviving fetuses were frequently stunted but gross malformations were rarely detected. Placentas frequently survived the fetuses and stayed in utero until term. Large intragastric doses of LS of E. typhosa had no effect on mothers and litters, which, if given i.p. would have been lethal.