Ohgami Nobutaka, Oshino Reina, Ninomiya Hiromasa, Li Xiang, Kato Masashi, Yajima Ichiro, Kato Masashi
Department of Occupational and Environmental Health, Nagoya University Graduate School of MedicineNagoya, Japan; Nutritional Health Science Research Center, Chubu UniversityKasugai, Japan.
Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine Nagoya, Japan.
Front Behav Neurosci. 2017 Feb 22;11:30. doi: 10.3389/fnbeh.2017.00030. eCollection 2017.
General electric devices and ventilation systems are known to generate low frequency noise (LFN) with frequencies of <100 Hz. Previous studies showed that exposure to LFN caused impairments of balance in humans and mice during adulthood. On the other hand, a previous study showed that noise levels in the neonatal intensive care unit (NICU) were greater than those in general home or office environments. Therefore, it is possible that neonates have a potential risk to be exposed to LFN in the NICU. However, the risk of neonatal exposure to LFN remains unclear in humans and mice. In this study, male ICR mice were exposed to LFN at 100 Hz for 4 weeks after birth and then subjected to rotarod and beam crossing tests in order to assess LFN-mediated risk of imbalance during the neonatal period. Exposure to LFN at 70 dB, but not exposure to LFN up to 60 dB, during the neonatal period significantly decreased performance scores for rotarod and beam crossing tests compared to the scores of the control group. The number of calbindin-positive hair cells in the saccule and utricle was decreased in mice exposed to LFN at 70 dB for 4 weeks in the neonatal phase. Cessation of exposure for 10 weeks did not result in recovery of the decreased performance in rotarod and beam crossing tests. Thus, our results suggest that 70 dB is a possible threshold for exposure to LFN for 4 weeks during the neonatal period causing unrecoverable imbalance in mice.
众所周知，通用电气设备和通风系统会产生频率低于100Hz的低频噪声（LFN）。先前的研究表明，成年期暴露于LFN会导致人类和小鼠的平衡能力受损。另一方面，先前的一项研究表明，新生儿重症监护病房（NICU）的噪音水平高于一般家庭或办公环境。因此，新生儿有可能在NICU中面临暴露于LFN的潜在风险。然而，人类和小鼠中新生儿暴露于LFN的风险仍不清楚。在本研究中，雄性ICR小鼠在出生后4周暴露于100Hz的LFN，然后进行转棒试验和横梁穿越试验，以评估新生儿期LFN介导的失衡风险。与对照组相比，新生儿期暴露于70dB的LFN，而不是高达60dB的LFN，显著降低了转棒试验和横梁穿越试验的性能得分。在新生儿期暴露于70dB的LFN 4周的小鼠中，球囊和椭圆囊内钙结合蛋白阳性毛细胞的数量减少。停止暴露10周并未导致转棒试验和横梁穿越试验中降低的性能恢复。因此，我们的结果表明，70dB可能是新生儿期暴露于LFN 4周导致小鼠不可恢复失衡的阈值。
