Morley Barbara J, Dolan David F, Ohlemiller Kevin K, Simmons Dwayne D
Center for Sensory Neuroscience, Boys Town National Research HospitalOmaha, NE, United States.
Kresge Hearing Research Institute, University of MichiganAnn Arbor, MI, United States.
Front Neurosci. 2017 Sep 21;11:516. doi: 10.3389/fnins.2017.00516. eCollection 2017.
We generated constitutive knockout mouse models for the α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits by derivation from conditional knockouts by breeding with CRE deleter mice. We then backcrossed them onto a C57BL/6J genetic background. In this manuscript, we report the generation of the strains and an auditory phenotypic characterization of the constitutive α9 and α10 knockouts and a double α9α10 constitutive knockout. Although the α9 and α10 nAChR subunits are relevant to a number of physiological measures, we chose to characterize the mouse with auditory studies to compare them to existing but different α9 and α10 nAChR knockouts (KOs). Auditory brainstem response (ABR) measurements and distortion product otoacoustic emissions (DPOAEs) showed that all constitutive mouse strains had normal hearing. DPOAEs with contralateral noise (efferent adaptation measurements), however, showed that efferent strength was significantly reduced after deletion of both the α9 and α10 subunits, in comparison to wildtype controls. Animals tested were 3-8 weeks of age and efferent strength was not correlated with age. Confocal studies of single and double constitutive KOs showed that all KOs had abnormal efferent innervation of cochlear hair cells. The morphological results are similar to those obtained in other strains using constitutive deletion of exon 4 of α9 or α10 nAChR. The results of our physiological studies, however, differ from previous auditory studies using a α9 KO generated by deletion of the exon 4 region and backcrossed onto a mixed CBA/CaJ X 129Sv background.
我们通过与CRE删除小鼠杂交，从条件性基因敲除小鼠中衍生出α9和α10烟碱型乙酰胆碱受体（nAChR）亚基的组成型基因敲除小鼠模型。然后将它们回交到C57BL/6J遗传背景上。在本论文中，我们报告了这些品系的产生以及组成型α9和α10基因敲除小鼠和α9α10双组成型基因敲除小鼠的听觉表型特征。尽管α9和α10 nAChR亚基与许多生理指标相关，但我们选择通过听觉研究来对小鼠进行特征描述，以便将它们与现有的但不同的α9和α10 nAChR基因敲除小鼠（KO）进行比较。听觉脑干反应（ABR）测量和畸变产物耳声发射（DPOAE）显示，所有组成型小鼠品系听力正常。然而，对侧噪声下的DPOAE（传出适应性测量）显示，与野生型对照相比，删除α9和α10亚基后传出强度显著降低。所测试的动物年龄为3 - 8周，传出强度与年龄无关。对单组成型和双组成型基因敲除小鼠的共聚焦研究表明，所有基因敲除小鼠的耳蜗毛细胞传出神经支配均异常。形态学结果与使用α9或α10 nAChR外显子4组成型缺失的其他品系所获得的结果相似。然而，我们的生理学研究结果与先前使用通过删除外显子4区域并回交到混合的CBA/CaJ X 129Sv背景上产生的α9基因敲除小鼠进行的听觉研究结果不同。
