Differences in the toxicity of soman in various strains of mice

The acute toxicity of soman was assessed in eight strains of mice (ALAS, CD-1, C57BL, CF1, CFW, C3H, DBA and BALB/c). In fasted animals the LD50 values for soman varied from 98 micrograms/kg in C57BL mice to 151 micrograms/kg in BALB/c mice. In general in non-fasted mice the soman LD50 was not significantly changed except in ALAS strain where the soman LD50 value increased significantly. The different sensitivities to soman poisoning among the various strains does not appear to be due totally to differences in level of brain acetylcholinesterase. Fasting had no significant effect on the activity of brain acetylcholinesterase and soman toxicity in CD -1 mice whereas, upon fasting ALAS strain mice for 18 hr, there was a 25% decrease in brain acetylcholinesterase which could explain their increased sensitivity to soman however, it is possible that other biochemical changes may also play a role.