Age-dependent sensitivity of the rat to neurotoxic effects of streptomycin.

Streptomycin sulfate (300 mg/kg s.c.) was injected for various periods into preweanling rats and for 3 weeks into weanling rats. Beginning at 8 days of age, body movement and hearing were examined for 6 and up to 17 weeks, respectively. Abnormal movements and deafness occurred only in rats treated during the preweaning period; within this period the greatest sensitivities for these abnormalities occurred from 2 to 11-17 and 5 to 11 days of age, respectively, indicating that the cochlea is more sensitive to streptomycin than the site (vestibular or central) responsible for the dyskinesias.