Aminoglycoside ototoxicity and efferent system: Comparison between acute and chronic gentamycin administration and the acute effects of other antibiotics

• Autor(a) principal: M.L. da Costa, Deise
• Data de Publicação: 2022
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Clinical and Biomedical Research
• Texto Completo: https://seer.ufrgs.br/index.php/hcpa/article/view/125215
• topic: Ototoxicidade; sistema eferente; gentamicina; nervo auditivo; Ototoxicity; efferent system; gentamicin; auditory nerve

OBJECTIVES: 1) To review the global base activity of the auditory nerve, the medial efferent olivocochlear system and the effect of aminosydes; 2) to investigate theblocking effect of gentamicin against the contralateral efferent supression of the ipsilateral cochlear activity using doses below 150 mg/kg; 3) to verify if this effectcould constitute an early sign of ototoxicity during a chronic treatment with gentamicin (60 mg/kg i.m. for 10 days); and 4) to determine if others aminosydes would have the same acute effects of gentamicin and if there would be a correlation between its specificities and ototoxicity degree and its potential to block the medial efferent system.MATERIALS AND METHODS: To test the function of the medial efferent olivocochlear system, the base electrical activity of the auditory nerve was tested in guinea pigsbefore and during a low contralateral acoustic stimulation intensity (55 dB SPL).RESULTS: Results show a dose-dependent effect of gentamicin on contralateral supression.The 120 mg/kg dose of gentamicin induced a smaller block of the medial efferent system compared to the 150 mg/kg, and no block was observed in smaller doses. During chronic treatment, no alteration either in the base activity of the auditory nerve without acoustic stimulation or in contralateral efferent supression was verified.The guinea pigs, monitored for several weeks after chronic treatment, presented a progressive reduction of the base activity of the auditory nerve without contralateral stimulation, in addition to a reduction in the coefficient of base activity suppressionand an increase in auditory limits, suggesting impairment of the cochlear function.CONCLUSION: Our results suggest that chronic gentamicin treatment (60 mg/kg), although ototoxic, does not affect contralateral efferent suppression, at least before the development of ototoxicity.