A Study of the Expression of Heat Shock Protein 72 in Guinea PigCochlea after Cisplatin Injection

Yu, Won Seok; Oh, Seung Ha; Kim, Chong Sun

Abstract

BACKGROUND AND OBJECTIVES: Several studies have attempted to show the reasons for ototoxicity induced by cisplatin, but the cochlear ototoxicity remained poorly understood. Recently, it is considered that free radicals play an important role in cisplatin ototoxicity. Heat shock proteins (HSP) are consistently present at some level in normal tissues and increased synthesis following stress. They have been implicated in the role of cellular protection during sub-lethal stressors. Many studies have demonstrated the increased synthesis of HSP following hyperthermia, ischemia, surgical injury and noise exposure. Free radicals are also considered as important inducer of HSP. The purpose of this study was to demonstrate the increase of HSP after cisplatin injection. MATERIALS AND METHOD: Thirty six Albano guinea pigs were used in this study. The animals were injected with a dose of 8 mg/kg cisplatin intraperitoneally. Cochleae are harvested 1, 3, 5 or 6, 12, 24 hours after injection. Immunocytochemistry and surface preparation method were used to detect the expression of HSP 72 in the cochlear tissues.
RESULTS
The level of HSP 72 immunoreactivity began increasing by 3 hours after injection and continued to increase thereafter to reach maximal levels at 6 hours. Twelve hours after injection, the level of HSP 72 seemed to decrease to its normal levels. The increase of HSP 72 was mainly detected in Deiters' cells.
CONCLUSION
Cisplatin induces a HSP in the guinea pig cochlea, particularly in the organ of Corti. However, further studies including quantitative analysis should be followed.