Enhanced toxicity of nervous system drugs for germ-free mice

Germ-free mice were found to be more sensitive than conventional mice to poisoning by hemicholinium-3, hexamethonium chloride, strychnine sulfate, sodium pentobarbital, sodium barbital, and histamine diphosphate. On the other hand, conventional mice were more sensitive to atropine. No difference between germ-free and conventional mice was found in sensitivity to d-tubocurarine, metrazol, and picrotoxin. These findings raise a question as to the influence of exposure to microorganisms in the development of sensitivity to drugs acting on the nervous system.