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INTRODUCTION: Auditory conditioning consists of the pre-exposure to low levels of a potential harmful agent to protect against a subsequent harmful exposure. OBJECTIVE: To confirm if conditioning with an agent different from that used to cause the trauma can also be effective. METHODS: This was an experimental study with 17 guinea pigs, divided into three groups: an ototoxic control group (Cont) that received intramuscular administration of gentamicin 160 mg/kg/day for ten consecutive days, but no sound exposure; a sound control group (Sound) that was exposed to 85 dB broadband noise centered at 4 kHz, 30 min each day for ten consecutive days, but received no ototoxic medications; and an experimental group (Expt) that received sound exposure identical to the Sound group and after each noise presentation, received gentamicin similarly to Cont group. The animals were evaluated by distortion product otoacoustic emissions (DPOAEs), brainstem auditory evoked potentials (BAEPs), and scanning electron microscopy. RESULTS: The animals that were conditioned with noise did not show any protective effect compared with the ones that received only the ototoxic gentamicin administration. This lack of protection was observed functionally and morphologically. CONCLUSION: Conditioning with 85 dB broadband noises, 30 min a day for ten consecutive days does not protect against an ototoxic gentamicin administration of 160 mg/kg/day for ten consecutive days in the guinea pig.

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INTRODUCTION: Auditory conditioning consists of the pre-exposure to low levels of a potential harmful agent to protect against a subsequent harmful presentation. OBJECTIVE: To confirm if conditioning with an agent different from the used to cause the trauma can also be effective. METHOD: Experimental study with 17 guinea pigs divided as follows: group Som: exposed to 85 dB broadband noise centered at 4 kHz, 30 minutes a day for 10 consecutive days; group Cont: intramuscular administration of gentamicin 160 mg/kg a day for 10 consecutive days; group Expt: conditioned with noise similarly to group Som and, after each noise presentation, received gentamicin similarly to group Cont. The animals were evaluated by distortion product otoacoustic emissions (DPOAEs), brainstem auditory evoked potentials (BAEPs) and scanning electron microscopy. RESULTS: The animals that were conditioned with noise did not show any protective effect compared to the ones that received only the ototoxic gentamicin administration. This lack of protection was observed functionally and morphologically. CONCLUSION: Conditioning with 85 dB broadband noise, 30 min a day for 10 consecutive days does not protect against an ototoxic gentamicin administration of 160 mg/kg a day for 10 consecutive days in the guinea pig. .

INTRODUÇÃO: O condicionamento auditivo consiste da pré-exposição de um agente lesivo em baixos níveis para proteger contra uma posterior apresentação lesiva. OBJETIVO: Confirmar se o condicionamento com um agente diferente do utilizado para causar o trauma pode ser efetivo. MÉTODO: Estudo experimental com 17 cobaias albinas divididas como a seguir- grupo Som: exposto a um ruído branco de 85 dB centrado em 4 kHz, 30 minutos por dia, por 10 dias consecutivos; grupo Cont: administração intramuscular de gentamicina 160 mg/kg por dia, por 10 dias consecutivos; grupo Expt: condicionado com ruído como o grupo Som. Após cada exposição ao ruído, recebeu gentamicina similarmente ao grupo Cont. Os animais foram avaliados por emissões otoacústicas produto de distorção (EOAPDs), potencial evocado auditivo de tronco encefálico (PEATE) e microscopia eletrônica de varredura (MEV). RESULTADOS: Os animais que foram condicionados com ruído não mostraram qualquer efeito protetor quando comparados com os que receberam apenas a gentamicina em doses ototóxicas. Esta ausência de proteção foi observada tanto funcionalmente quanto morfologicamente. CONCLUSÃO: Os autores concluíram que o condicionamento com ruído branco a 85 dB por 30 minutos, por dia por 10 dias consecutivos, não protege contra uma administração de gentamicina 160 mg/kg/dia, por 10 dias consecutivos. .

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UNLABELLED: Radiation can cause damage to the inner ear, from a simple hearing loss all the way to profound deafness. Amifostine is a cytoprotective substance extensively used during radio-chemotherapy for malignant tumors. AIM: the objective of the present investigation was to establish the antioxidant and radioprotective effects of amifostine on the organ of Corti of albino guinea pigs irradiated in the head and neck region. MATERIALS AND METHODS: An experimental study conducted on four groups of guinea pigs were used; One group received only amifostine, one group was submitted to a single dose of 350 cGy and the other two were similarly irradiated but received amifostine doses of 100 or 200 mg/kg. All animals were slaughtered 30 days after the experiment, their bullae were removed and the damaged outer hair cells were counted. RESULT: The extent of injury was lower in the outer hair cells of the two groups treated with amifostine compared to the group that was only irradiated. There was no difference between the group treated with 100 and 200 mg/kg of amifostine. The group that received only amifostine had no cochlear damage. CONCLUSION: Amifostine is an effective cytoprotective substance in the Organ of Corti of irradiated guinea pigs.

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Nesta revisäo dirigida ao graduando em Medicina e ao médico näo especialista, apresentou-se os principais elementos semiológicos das fossas nasais, seios paranasais, laringe, faringe e ouvidos.

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