1978 年 71 巻 5special1 号 p. 540-550
We analyzed the development of auditory disorders in fetuses and infants.
The naturally delivered newborn rats that had ingested antibiotics through their mothors were studied to determine Preyer's auricle reflex and the auditory vertex evoked potential. (AEP).
Dosages of 400mg/kg and 200mg/kg of Kanamycin, 200mg/kg of Dideoxykanamycin B and 150mg/kg of Gentamicin were administered to the newborn for 7 to 10 consecutive days during five different periods between 24 hours and 40 days after their birth. The animals were anesthetized with Nembutal 30mg/kg given intraperitoneally.
We first checked the development of hearing in the normal newborn. Their evoked potential was obtained 11 or 12 days after birth and by 16 to 20 days after birth, the value of the potential was about the same as adult rats.
The value of auditory vertex evoked potential of newborn to which the antibiotics had been administered was then determined. During the embryonic period and newborn period of 1 to 7 days, little or no effect of the antibiotics was observed. On the other hand, administration of doses at 10 to 14 days after birth produced serious side effects. Such adverse effects were not apparent in the samples from rats given the drugs after the 16th day of birth.
Our results indicate that the aminoglycoside antibiotics have a serious effect on the hearing of the rats around 10 to 14 days after birth.