Prestin基因敲除小鼠听力和毛细胞改变的相关性研究

目的研究发育和成熟过程中的prestin基因敲除小鼠听力特征,比较其听力损害和外毛细胞(OHC)丧失的相关性,初步探讨OHC丧失的机制.方法利用听性脑干反应(ABR)、抗小鼠耳蜗毛细胞特异性的肌浆球蛋白7a(Mysojn 7a)抗体免疫染色和耳蜗连续切片观察出生后(postnatal,P)14天(P14)～P56的prestin基因敲除纯合子(prestin-/-)、杂合子(prestin /-)和野生型(prestin / )小鼠听阈、耳蜗毛细胞和Corti器的改变.结果P14的prestin-/-小鼠听阈较prestin / 升高25 dB SPL,至P21和P28,听阈分别提高49 dB和52 dB,P35后听阈改变不明显.在P21的prestin-/-小鼠,32 kHz听阈提高46 dB;prestin /-也显示约3.5 dB的听阈升高(p＜0.0001).Prestin-/-小鼠在P28以前无明显的OHC丧失,但是,OHC的长度较prestin / 明显缩短,P28以后,OHC丧失进行性加重.内毛细胞(IHC)丧失明显延迟和轻于OHC.结论Prestin-/-小鼠在毛细胞丧失之前呈现明显的听力损害,OHC的丧失可能与其本身的结构改变和成熟过程中的代谢异常有关.

A correlative study of the alterations of hearing and hair cells in prestin knockout mice

Objective To study hearing features of prestin gene knockout mice during development and maturation,compare the correlation of the loss of outer hair cells(OHC) with hearing and preliminarily explore the mechanism of OHC loss. Methods The changes of hearing thresholds, hair cells and the organ of Corti in homozygous (prestin-/-), heterozygous (prestin /-)prestin knockout mice and their wild type (prestin / ) mice from postnatal day 14 (P14) to P56 were investigated by auditory brain stem response(ABR), cochlear whole mounts immunostaining of anti-myosin 7a antibody and series sections of the cochleae. Results The prestin-/- mice showed hearing loss of 25 dB at P14, and up to P21 and P28, their hearing loss were 49 dB and 52 dB, respectively. After P35, hearing thresholds were not obviously elevated. At P21, hearing loss of 32 kHz in prestin-/- mice was 46 dB, and prestin /- mice also displayed a significant hearing damage (approximately 3.5 dB, p<0.0001). Before P28, no significant hair cell loss occurred in prestin-/- mice, and the length of OHCs was shorter than that of prestin / at this stage. The loss of OHCs was increasingly exacerbated when they were above P28. The loss of inner hair cells (IHC) was lagging and light as compared with that of OHCs. Conclusion The prestin-/- mice showed obvious hearing loss before the loss of hair cells, and this suggested that the loss of OHCs might result from the structural alteration of their lateral plasma membrane, and also could be related with the abnormality of metabolism during their maturation.