Endocochlear potentials and compound action potential recovery: functions in the C57BL/6J mouse
Endocochlear potentials and compound action potential recovery: functions in the C57BL/6J mouse
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DOI：
10.1016/s0378-5955(02)00552-x
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发表时间：
2002-10-01
期刊：
影响因子：
2.8
通讯作者：
Schmiedt, RA
中科院分区：
文献类型：
--
作者：
Lang, H;Schulte, BA;Schmiedt, RA
C57BL/6J小鼠从小就患有耳蜗性退行性变，被用作老年性听力损失(老年性耳聋)的模型。测定了1月龄、4月龄、12月龄和24月龄C57BL/6J小鼠的耳蜗内电位(EP)和复合动作电位(CAP)反应。CAP措施包括音调点数的阈值、输入/输出(I/O)功能和条件音调的恢复功能。四个年龄组的EP值在基底弯和心尖转角上均无显著差异(P>；0.05)。在11.3、16、20和22.6 kHz频率下，4个月组与1个月对照组相比，CAP阈值显著增加了10~30分贝。与对照组相比，四个月组的CAP I/O功能在所有频率下都较浅。在12个月和24个月大的小鼠中，CAP反应缺失，尽管这些动物的EP值正常。在8、16、20和22.6 kHz的频率下，获得了条件反射后的恢复功能；在1月龄和4月龄组中，在所有频率下都测试了这些功能的快慢成分。两个年龄组的相应恢复曲线是相同的，即使老年组的阈值发生了显著变化。这两种成分的恢复曲线首次提供了C57BL/6J小鼠存在不同自发频率(SR)的听神经元的生理学证据。此外，老年组中不变的恢复函数表明，在EP保持稳定的情况下，低SR纤维群体的活性没有随年龄而丧失，而与老年性耳聋模型相反，在老年性耳聋模型中，低SR纤维活性丧失，EP确实随年龄下降。(C)2002 Elsevier Science B.V.保留所有权利。
The C57BL/6J mouse suffers from cochlear degeneration beginning at an early age and has been used as a model of age-related hearing loss (presbyacusis). Here, the endocochlear potential (EP) and compound action potential (CAP) responses were determined in one-, four-, 12- and 24-month-old C57BL/6J mice. CAP measures included thresholds to tone pips, input/output (I/O) functions, and recovery functions to conditioning tones. EP values among the four age groups did not differ significantly (P > 0.05) in either the basal or apical turns. CAP thresholds were increased significantly by 10 to 30 dB in the four-month group compared to the one-month controls at 11.3, 16, 20, and 22.6 kHz. CAP I/O functions were shallower in the four-month group compared to controls at all frequencies. In the 12- and 24-month-old mice, CAP responses were absent, despite normal EP values in these animals. Recovery functions after conditioning tones were obtained at 8, 16, 20 and 22.6 kHz; the functions had fast and slow components at all frequencies tested in both the one- and four-month-old groups. The corresponding recovery curves were identical for both age groups, even with significant threshold shifts in the older group. The two component recovery curves provide the first physiological evidence that different spontaneous rate (SR) classes of auditory neurons exist in the C57BL/6J mouse. Moreover, the unchanged recovery functions in the older group suggest that there was no loss of activity of the low-SR fiber population with age under conditions where the EP remains stable, in contrast to the gerbil model of presbyacusis where there is a loss of low-SR fiber activity and EP does decline with age. (C) 2002 Elsevier Science B.V. All rights reserved.