Ryugo D K, Pongstaporn T, Huchton D M, Niparko J K
Department of Otolaryngology-Head and Neck Surgery, Center for Hearing Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
J Comp Neurol. 1997 Aug 25;385(2):230-44. doi: 10.1002/(sici)1096-9861(19970825)385:2<230::aid-cne4>3.0.co;2-2.
Changes in structure and function of the auditory system can be produced by experimentally manipulating the sensory environment, and especially dramatic effects result from deprivation procedures. An alternative deprivation strategy utilizes naturally occurring lesions. The congenitally deaf white cat represents an animal model of sensory deprivation because it mimics a form of human deafness called the Scheibe deformity and permits studies of how central neurons react to early-onset cochlear degeneration. We studied the synaptic characteristics of the endbulb of Held, a prominent auditory nerve terminal in the cochlear nucleus. Endbulbs arise from the ascending branch of the auditory nerve fiber and contact the cell body of spherical bushy cells. After 6 months, endbulbs of deaf white cats exhibit alterations in structure that are clearly distinguishable from those of normal hearing cats, including a diminution in terminal branching, a reduction in synaptic vesicle density, structural abnormalities in mitochondria, thickening of the pre- and postsynaptic densities, and enlargement of synapse size. The hypertrophied membrane densities are suggestive of a compensatory response to diminished transmitter release. These data reveal that early-onset, long-term deafness produces unambiguous alterations in synaptic structure and may be relevant to rehabilitation strategies that promote aural/oral communication.
通过实验性地操纵感觉环境，可以引起听觉系统结构和功能的变化，而剥夺程序会产生特别显著的影响。另一种剥夺策略利用自然发生的损伤。先天性耳聋的白猫代表了一种感觉剥夺的动物模型，因为它模拟了一种称为Scheibe畸形的人类耳聋形式，并允许研究中枢神经元对早发性耳蜗退化的反应。我们研究了Held终球的突触特性，Held终球是耳蜗核中一个突出的听觉神经末梢。终球起源于听觉神经纤维的升支，并与球形多毛细胞的胞体接触。6个月后，耳聋白猫的终球在结构上出现了明显不同于正常听力猫的变化，包括终末分支减少、突触小泡密度降低、线粒体结构异常、突触前和突触后致密物增厚以及突触大小增大。肥大的膜致密物提示对递质释放减少的一种代偿反应。这些数据表明，早发性、长期耳聋会导致突触结构发生明确的改变，这可能与促进听觉/口语交流的康复策略有关。
