Tanyeri H, Lopez I, Honrubia V
Division of Head and Neck Surgery, Victor Goodhill Ear Center, UCLA School of Medicine 90024, USA.
Hear Res. 1995 Sep;89(1-2):194-202. doi: 10.1016/0378-5955(95)00137-7.
Two experiments were conducted to study the ototoxic effects of local gentamicin (GM) administration and the subsequent hair cell (HC) regeneration process in the chinchilla cristae ampullares (CA). In the first experiment, 3 different doses of GM (0.1, 0.2 and 1.2 mg) were administered by surgical implantation of GM-soaked Gelfoam pledgets in the perilymphatic space in the otic capsule of the left superior semicircular canal. The CA was histologically processed for light-microscopic examination. In the second experiment, 6 groups of 2 chinchillas each were treated with 0.1 mg of GM. To document cell proliferation and HC regeneration, Alzet micro-osmotic pumps were implanted in each chinchilla to deliver bromodeoxyuridine (BrdU) at 125 micrograms/h for 1 week. Chinchillas were subsequently killed at 1 and 4 days and 1, 2, 4 and 8 weeks post-treatment (PT). The CA was processed for light microscopy and BrdU immunocytochemistry. In the first experiment the smallest dose produced damage restricted to HCs alone, while the medium and large doses produced severe damage in the sensory epithelium, including supporting cells and HCs. Results in the second experiment demonstrated that at 1 and 4 days PT the HCs showed extensive damage, including clumping of nuclear material. By 4 days PT the supporting cell nuclei lost their monolayer configuration. Calyceal terminals appeared empty, and vacuolized remnants of nerve calyces were evident in the basal portion. At 1 week PT complete disappearance of HCs from the sensory epithelium was evident, and there was cytoplasmic extrusion into the endolymphatic space. At 2 weeks PT there was complete HC loss, the supporting cell nuclei were scattered randomly in the crista, and the nerve fibers were retracted from the sensory epithelium. At 4 weeks PT there was evidence of sensory epithelium repair and HC regeneration. Short cells resembling type-II HCs were evident in the surface of the sensory epithelium. At 8 weeks PT the number of HCs increased in a uniform fashion on the surface of the sensory epithelium, and the supporting cell nuclei were realigned on the basal membrane. Nerve fibers with growth cones penetrated the basal membrane. Supporting cell proliferation was evident by the presence of mitotic figures and BrdU immunoreactivity in the chromatin material of dividing cells at 2 weeks PT. The labeling was more evident in newly formed cells at 4 and 8 weeks PT. These results demonstrate that in chinchillas the vestibular organs have the capacity of self-repair and the process includes HC regeneration after local administration of GM. The overall process involves changes in different cells in the sensory epithelium and neural elements, all of which show modifications with an orderly pattern.
进行了两项实验，以研究局部给予庆大霉素（GM）对灰鼠壶腹嵴（CA）的耳毒性作用以及随后的毛细胞（HC）再生过程。在第一个实验中，通过将浸泡过GM的明胶海绵小块手术植入左上前庭半规管耳囊的外淋巴间隙，给予3种不同剂量的GM（0.1、0.2和1.2毫克）。对CA进行组织学处理以进行光学显微镜检查。在第二个实验中，将6组，每组2只灰鼠用0.1毫克GM进行处理。为记录细胞增殖和HC再生，在每只灰鼠体内植入Alzet微量渗透泵，以125微克/小时的速度输送溴脱氧尿苷（BrdU），持续1周。随后在处理后（PT）1天、4天以及1周、2周、4周和8周处死灰鼠。对CA进行光学显微镜检查和BrdU免疫细胞化学分析。在第一个实验中，最小剂量仅对HC造成损伤，而中等剂量和大剂量则对感觉上皮造成严重损伤，包括支持细胞和HC。第二个实验的结果表明，在PT后1天和4天，HC显示出广泛损伤，包括核物质聚集。到PT后第4天，支持细胞核失去单层结构。杯状终末看起来空虚，神经杯状突的空泡化残余物在基部明显可见。在PT后1周，感觉上皮中的HC明显完全消失，并且有细胞质挤入内淋巴间隙。在PT后2周，HC完全丧失，支持细胞核随机散布在嵴中，神经纤维从感觉上皮缩回。在PT后4周，有感觉上皮修复和HC再生的证据。在感觉上皮表面可见类似于II型HC的短细胞。在PT后8周，感觉上皮表面的HC数量以均匀方式增加，支持细胞核在基膜上重新排列。带有生长锥的神经纤维穿透基膜。在PT后2周，通过有丝分裂图的存在以及分裂细胞染色质材料中的BrdU免疫反应性，支持细胞增殖明显。在PT后4周和8周，标记在新形成细胞中更明显。这些结果表明，在灰鼠中，前庭器官具有自我修复能力，该过程包括局部给予GM后的HC再生。整个过程涉及感觉上皮和神经元件中不同细胞的变化，所有这些变化都呈现出有序的模式。
