RESUMO
BACKGROUND AND OBJECTIVES: Interleukin (IL)-1beta has been detected in human middle ear effusion (MEE) and the MEEs of experimental otitis media. The object of this study was to investigate whether this cytokine 1) penetrates through the round window membrane (RWM) and 2) induces hearing loss. MATERIALS AND METHODS: Guinea pigs were randomly assigned as control and IL-1beta groups and each was subdivided into three different groups by applying 1 ng, 10 ng, 100 ng of IL-1beta on RWM. They underwent hearing test by auditory brainstem response (ABR) prior to experiments. In the ontrol group, 5nL of phosphate buffered saline (PBS) soaked in a small piece of gelfoam was applied on the RWM. In IL-1beta groups, three different concentrations of IL-1beta 1 ng, 10 ng, 100 ng soaked in a small piece of gelfoam were applied on the RWM. ABR measurements were performed at 3 and 6 hours after application of different concentrations of IL-1beta. At the end of 6 hours, cochleas were harvested and perilymphs were collected for assay of IL-1beta level by the ELISA method. RESULTS: At 6 hours after application, the control group animals did not show any significant hearing loss. The IL-1beta were undetectable in perilymph of control group. In IL-1beta group, IL-1beta was detected in perilymph in dose dependent increasing concentrations. There was a significant hearing loss in this IL-1beta group in dose dependent manner in 3 and 6 hours. The hearing loss in 100 ng was significant comparing to control group. CONCLUSION: The result of this study indicated that IL-1beta applied on RWM penetrate to the perilymph and caused hearing loss. The result of this study suggest that IL-1beta in MEE may cause sensorineural hearing loss in guinea pig.