Effects of an Aminoglycoside on Pregnant Mice and on the Postnatal Development of Their Offspring

Abstract

Aminoglycoside treatment during pregnancy is known to have toxic effects on the postnatal development of the audiocochlear system of neonates. The authors examined postnatal physiological and morphological changes in offspring of ICR mice given intraperitoneal injections of streptomycin sulphate (SM), and kanamycin sulphate (KM) from day 12 to day 18 of gestation (250mg/kg/day of SM and 500mg/kg/day of KM). In the control group, 1ml of physiological saline was injected intraperitoneally during the same period of gestation. Sixty offspring (SM: 20, KM: 20 and control: 20) were examined functionally by behavior tests, and the morphological changes in the inner ear were studied by scanning electron microscope. The results of the behavior tests were analyzed statistically. No significant differences were found between the control and experimental groups in average body weight increase, activity, or functional development such as grooming. In the period of development of the Auditory Startle Response, the responsiveness of the KM group was significantly less than that of the SM or control group. The KM group had more severe morphological changes, characterized by polyp-like cytoplasmic extrusions of the inner hair cells in the cochlea. The Transversing Narrow Path and Rotor Rod test success rate was lower in the SM and KM groups than in the control group.Disarray of the step-like formation and degeneration of sensory cells were the main abnormalities along the striolas of the macula utriculi in the KM and SM groups. The damage was more severe in the SM than in the KM group.