| Abstract: | The remarkable susceptibility of the inner ear of the patas monkey (Erythrocebus patas) to the ototoxic action of dihydrostreptomycin (DHSM) (and streptomycin (SM)) is well established in this paper and affords a rare example of a species-specific reaction to a restricted class of compounds within the aminoglycoside group of antibiotics. In a series of experiments, behavioral and morphological observations together provided the following profile of DHSM ototoxicity in the patas monkey: Sudden onset of hearing loss beginning after 7-9 weeks of treatment; Substantial, though often partial, hearing impairment beginning at the high frequencies and progressing with or without continued treatment to the low frequencies; In the inner ear, a corresponding and selective loss of nerve fibers and of outer hair cells, relative to inner hair cells, beginning in the base of the cochlea and proceeding toward the apex; Continued and progressive loss of hearing for several months after cessation of drug treatment; and Non-auditory effects in some animals on the kidney and vestibular system. Results from control experiments confirmed this special relationship between the patas monkey and DHSM: Other nonhuman primates (macaques and vervet monkeys) were essentially unaffected by DHSM; The patas showed no equivalent sensitivity to other aminoglycosides such as kanamycin or to other forms of ototraumatic insult such as intense noise. |
