Otitis media with effusion in an allergic animal model: A functional and morphological study.

OBJECTIVES: Allergy is considered as one of important etiologic factor of otitis media with effusion (OME). In present study, we evaluated the causal effect of allergy on OME in an animal model, and investigated the secondary effect of bacterial infection. METHODS: Allergy and control animals were subdivided into groups with and without intratympanic injection of lipopolysaccharide (IT-LPS). Allergic otitis media was induced via intraperitoneal ovo-albumin injection with intranasal challenge. We assessed the occurrence of OME in allergic animals and the effect of IT-LPS on allergic otitis media. We also investigated the Th1 and Th2 responses in the middle-ear mucosa. Hearing of the animals was measured by ABR and DPOAE. RESULTS: OME was observed in 75% of the allergic animals. After IT-LPS, 100% of the control and allergy groups showed otitis media. Light microscopy revealed that the middle-ear mucosa of animals of both groups also was significantly increased after IT-LPS, and the Th1 response (IL-2 and IFN-γ) and Th2 response (IL-5 and IL-13) cytokines were expressed at higher levels in the allergy group with IT-LPS than in control group with IT-LPS. Hearing tests between the allergy and control group with IT-LPS did not reveal any differences. CONCLUSION: Our findings may be direct evidence of an allergic causal effect on OME. Th2 response cytokines were strongly expressed in allergic OME, and the inflammatory reaction to LPS was more intense in the allergic group, which indicates that otitis media related to allergy can be severely aggravated by an inflammatory reaction to bacterial infection.

Protective effect of unilateral and bilateral ear plugs on noise-induced hearing loss: functional and morphological evaluation in animal model.

The aim of the following study is to evaluate immediate protective effect of ear plug from noise morphologically and functionally. An 1-month aged 29 male C57BL/6 mice. Subjects were divided into four groups as normal control(G1), bilaterally plugged group (G2), unilaterally plugged group (G3) and noise control group (G4) and later 3 groups were exposed to 110 sound pressure level white noise for 60 min. Immediately after noise exposure, audiologic tests were performed and cochlear morphology and expression levels of a-synuclein in the cochlea were investigated. There were no functional changes in G2 and plugged ears of G3 after noise exposure, whereas unplugged ears of G3 and G4 showed significant hearing loss. In morphological study, there were a significant degeneration of the organ of Corti and mean number and diameter of efferent buttons, in unplugged ears of G3 and G4. Plugged ears of G3 also showed mild changes in morphological study. Reduction of a-synuclein was observed at the efferent terminals or cochlear extracts after noise exposure. The protective effect of ear plug on noise exposure was proven morphologically and functionally in the animal model of noise-induced hearing loss. Further study on cellular or ultrastructural level with ear plug will be needed to reveal more precise mechanism.