生理状态下小鼠听阈及耳蜗内IL-1β、IL-6、TNF-α、CCL-2和GR mRNA水平昼夜变化的研究

Patterns of Physiological Circadian Changes of Hearing Thresholds and Messenger RNA Levels of IL-1β,IL-6,TNF-α,CCL-2 and GR in Cochlea in Mice

目的监测正常生理状态下一天内不同时间点小鼠耳蜗内常见炎症介质和糖皮质激素受体的mRNA水平,同时监测小鼠听性脑干反应测听(ABR)阈值及ABR I波幅值和潜伏期,以期探讨昼夜节律对耳蜗生理指标的影响。方法在小鼠生理状态下不同时间点(00:00,04:00,08:00,12:00,16:00,20:00)用ABR和实时荧光定量PCR的方法监测ABR听阈、I波幅值和潜伏期、耳蜗内常见炎症介质(IL-1β、IL-6、TNF-α、CCL-2)和糖皮质激素受体的mRNA含量。结果在生理状态下不同时间点小鼠的听阈、I波的幅值和潜伏期无统计学差异,小鼠耳蜗内IL-6、TNF-α、CCL-2和糖皮质激素受体的mRNA含量亦无统计学差异,但与00:00,04:00和08:00相比,20:00 IL-1β的mRNA含量明显升高,并有统计学差异(P=0.002,P=0.005,P=0.001)。结论生理状态下小鼠听阈、I波幅值和潜伏期在一天内无明显变化,但耳蜗内IL-1β的mRNA含量在一天内并不恒定。

Objective To report mRNA levels of several inflammatory mediators and glucocorticoid receptors in the cochlea at different time points under normal physiological conditions,as well as auditory brainstem response(ABR)thresholds,wave I amplitude and latency in mice,as indicators of influence of circadian rhythm on the cochlea.Methods At different time points(00:00,04:00,08:00,12:00,16:00 and 20:00),ABR thresholds and wave I amplitude and latency,and real-time fluorescence quantitative PCR of mRNA contents of inflammatory mediators(IL-1β,IL-6,TNF-αand CCL-2)and glucocorticoid receptors in the cochlea were collected in mice.Results There was no statistically significant change in ABR threshold or wave I amplitude and latency at different time points,nor in the mRNA level of IL-6,TNF-α,CCL-2 and glucocorticoid receptors,although the mRNA level of IL-1βat 20:00 was higher as compared with that at 00:00,04:00 and 08:00(P=0.002,P=0.005 and P=0.001,respectively).Conclusion Under physiological conditions,ABR threshold,wave I amplitude and latency do not show significant changes over the period of 24h,although the mRNA level of IL-1βin the cochlea is not constant in a day.