Application of a shuttle avoidance schedule in rats to evaluate a drug-induced auditory irnpairment

In attempts to study drug-induced auditory impairment we measured the auditory threshold in rats, using the shuttle box method. The auditory threshold with physical impairment of ears was also measured. The sensitivity of the rats to the auditory response was decreased to about 15dB in cotton-stuffed ears and to about 20dB in pierced eardrums. In this experiment, we used drugs known to be ototoxic; dihydrostreptomycin sulfate, kanamycin sulfate, neomycin sulfate and ethacrynic acid. With successive administration of each drug, the auditory sensitivity in rats decreased. This shuttle box method is easily facilitated and the auditory threshold of many rats can be measured over a short period. This approach may be a useful method for screening ototoxic drugs.