title: Effects of noise exposure on neonatal auditory brainstem response thresholds in pregnant guinea pigs at different gestational periods.
abstract: OBJECTIVE
  Noise exposure during pregnancy has been reported to cause fetal hearing impairment. However, little is known about the effects of noise exposure during various gestational stages on postnatal hearing. In the present study, we investigated the effects of noise exposure on auditory brainstem response (ABR) at the early, mid-, and late gestational periods in newborn guinea pigs.
  
  
  METHODS
  Pregnant guinea pigs were exposed to 4-kHz pure tone at a 120-dB sound pressure level for 4 h. We divided the animals into four groups as follows: the control, early gestational exposure, mid-gestational exposure, and late gestational exposure groups. ABR thresholds and latencies in newborns were recorded using 1-, 2-, and 4-kHz tone burst on postnatal days 1, 7, 14, and 28. Changes in ABR thresholds and latencies were measured between the 4 × 4 and 4 × 3 factorial groups mentioned above (gestational periods × postnatal days, gestational periods × frequencies).
  
  
  RESULTS
  The thresholds were low in the order of control group < early gestational exposure group < mid-gestational exposure group and late gestational exposure group. Noise exposure during pregnancy influenced ABR thresholds in neonatal guinea pigs.
  
  
  CONCLUSIONS
  This is the first study to show that noise exposure during the early, mid-, and late gestational periods significantly elevated ABR thresholds in neonatal guinea pigs.
authors.affiliation: Department of Otorhinolaryngology - Head and Neck Surgery, Nara Medical University, Kashihara, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Morimoto
authors.affiliation: Department of Otorhinolaryngology - Head and Neck Surgery, Nara Prefecture General Medical Center, Nara, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nario
authors.affiliation: Department of Otorhinolaryngology - Head and Neck Surgery, Nara Medical University, Kashihara, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nishimura
authors.affiliation: Interdisciplinary Graduate School of Science & Engineering, Area of Architecture and Production Design Engineering, Shimane University, Matsue, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Shimokura
authors.affiliation: Department of Otorhinolaryngology - Head and Neck Surgery, Nara Medical University, Kashihara, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hosoi
authors.affiliation: Department of Otorhinolaryngology - Head and Neck Surgery, Nara Medical University, Kashihara, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kitahara
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D005865:Gestational Age; D006168:Guinea Pigs; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D009622:Noise / Q000009:adverse effects*; D011247:Pregnancy
keywords: auditory brainstem response; fetus; gestational period; guinea pig; noise exposure