Effect of Platelet-activating Factor on Hearing and Cochlear Hair Cells in Guinea Pigs

Rhee, Chung Ku; Jang, Yong Ju; Kim, Young Hoon; Hyun, Min Hwan; Kim, Han Gyun; Park, Chan Il

Abstract

BACKGROUND AND OBJECTIVE: Inflammatory mediators released in the middle ear cavity appear to play an important role in the pathogenesis of otitis media and can cause functional as well as morphological changes in the inner ear. Recent studies have also implicated platelet-activating factor (PAF) to be involved in the pathogenesis of otitis media with effusion in addition to prostaglandines (PGs) and leukotrienes (LTs). PAF appears to be important in the acute inflammatory process of otitis media. The purpose of this study is to determine the effects of PAF placed on round window membrane (RWM) on hearing and cochlear hair cells in guinea pigs.
MATERIALS AND METHODS
Control group and PAF group received RWM application of phosphate buffered saline (PBS) and PAF 1 ng/ml, respectively. Using auditory brainstem response (ABR), the hearing threshold of both group was measured every 2 hours duirng the 8 hours after placement of PBS or PAF. At the end of the eight hour, the harvested cochlears were prepared for scanning electron microscopy (SEM) study.
RESULTS
There were mild to moderate increase in the ABR threshold from 2 to 8 hours after the application of PAF on the RWM in PAF group. When the threshold levels of the PAF group and the control group were compared, statistically significant differences were observed between the two groups (p<0.05). In SEM study, both inner and outer hair cells were found to be damaged.
CONCLUSION
The exogenous PAF-induced hearing loss may have been due to the cochlear hair cell damage caused by these exogenous PAF. Thus, PAF may play an important role in the sensorineural hearing loss in otitis media with effusion.