X-连锁低磷酸盐血症Pug小鼠的听力学和耳形态学研究

The auditory research of Pug mice with X-linked hypophosphatemia

目的Phex基因点突变Pug小鼠是典型的人类X-连锁低磷酸盐血症小鼠模型。通过研究Pug小鼠的听力学表型,探讨Phex基因点突变对小鼠听觉功能与内耳形态的影响。方法运用听性脑干诱发电位(ABR)对4月龄Pug小鼠和野生型小鼠进行听功能测试,取小鼠耳蜗进行大体形态观察,运用石蜡切片观察小鼠耳蜗骨壁、前庭膜、血管纹、螺旋韧带、盖膜、Corti器、螺旋神经节等结构。运用扫描电镜观察小鼠耳蜗Corti器上的内、外毛细胞及其表皮板等结构。结果Pug小鼠的ABR在短声和8kHz、16kHz、32kHz短纯音刺激的反应阈值均有提高,在短声和16kHz、32kHz频率,其差异具有统计学意义(P<0.05)。小鼠耳蜗骨壁增厚,骨质过度增长,有大量骨质矿化不完全区域;耳蜗底转部位螺旋神经节出现明显退化,神经元数目大量减少;耳蜗顶转到底转内、外毛细胞静纤毛散在性缺失,静纤毛形态异常。结论Phex基因点突变引起的基因功能缺失导致了Pug小鼠的听觉功能减退和耳蜗形态异常。

Objective Phex gene mutant mouse Pug is a model for X- linked hypophosphatemia. In order to investigate the effect of Phex gene on the auditory function and cochlear morphology, auditory phenotype was evaluated in Pug mice. Methods Auditory brainstem responses（ABR） of 4-month-old Pug mice and wildtype mice were examined in response to click and 8, 16 and 32 kHz tone burst stimulation. The gross morphology of the Pug mice cochlea was examined by stereomicroscopy. The bony shell of cochlea, vestibular membrane, stria vascularis, spiral ligament, tectorial membrane, the organ of Corti and spiral ganglion cells were analyzed by H-E staining of the paraffin sections. The inner and outer hair cells of the organ of Corti and their cuticular plate were characterized by using scanning electron microscopy. Results ABR thresholds in Pug mice were elevated compared with wild type mice. Statistical significance was distinguished in ABR thresholds to click and 16 kHz and 32 kHz tone burst stimuli. The bony shell of the mutant cochlea was thickened and overgrown with many nonmineralization regions. The number of spiral ganglion neurons decreased in the basal turn. Abnormal stereocilia and reduction in number of inner and outer hair cells of the organ of Corti were identified from the apex to the basal turn by scanning electron microscopy. Conclusion The impaired hearing and the morphological abnormalities of the inner ear in pug mice are induced by the loss-of-function mutation of Phex gene.