[Effect of epidermal growth factor and dexamethasone on blast hearing loss]

The expression of epidermal growth factor receptor (EGFR) in cochlear hear cells was studied in normal and guinea pigs exposed to blasts. The effects of epidermal growth factor (EGF) and dexamethasone (DXM) treatment for blast hearing loss and the underlying mechanisms were also explored. Scattered expression of EGFR was seen in IHCs and OHCs in normal guinea pigs. Segmentally distributing positive reaction was also located in stereocillia of hair cells. Distribution of EGFR reaction was seen in the cytoplasm of IHC 24 hours after exposure to blasts, and in the stereocillia of IHC and the cuticular plate of OHC 72 hours postexposure. At one week EGFR reaction in hair cells increased obviously and part of OHC stereocillia also showed positive reaction. EGFR reaction reduced at two weeks, though positive reaction could still be found in the stereocillia of hair cells at one month. Combination of EGF and DXM administrations promoted hearing recovery significantly. Our results suggest that healing of injured hair cells may be to EGF.