Abstract:

Objective       To investigate whether apoptosis is one of the mechanism in the immune  response of the inner ear and to detect expression of Bcl-2 and Bax in inner ears. Methods      Sixty healthy SD rats were divided into the experimental group(30 systematically injected with type Ⅱcollagen and freund adjuvant), the adjuvant group(15 injected with freund adjuvant) and the control group(15 injected with the same volume of saline). DPOAE was performed and scanning electron microscopy was applied to evaluate cochlear morphology．The TUNEL method was used to detect apoptotic cells in inner ear immume response. The immunohistochemical method was applied to detect expression of Bcl-2 and Bax. Results      DPOAE amplitudes decreased and the cilia of hair cells mostly disappeared with spaces between hair cells in the experimental group compared with the adjuvant group and control group(P<0.05).TUNEL-positive cells could be detected in the corti organ, stria vascularis and  spiral ganglion cells and the ratio of Bcl-2/Bax increased in the experimental group. Conclusions      These findings suggest apoptosis is involved in the pathogenesis of the immune response of inner ears and Bcl-2 and Bax play critical roles in it.

Key words: Type II collagen; Autoimmune inner ear disease; Apoptosis;Bcl-2 and Bax；DPOAE