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The Induction of Hypothyroidism during Gestation Decreases Outer Hair Cell Motility in Rat Offspring

Priscila Feliciano de Oliveira1,2,3, Beatriz Barros Santos Trindade2, Paloma Fonseca Martins Reis2

  • 1Department of Health Sciences, Universidade Federal de Sergipe, São Cristóvão, SE, Brazil.

International Archives of Otorhinolaryngology
|November 21, 2022
PubMed

Insights

Perinatal hypothyroidism in rats causes permanent hearing loss by damaging cochlear outer hair cells. This study reveals long-term auditory system effects in adult offspring.

Area of Science:

  • Neuroscience
  • Otolaryngology
  • Developmental Biology

Background:

  • Perinatal hypothyroidism negatively impacts auditory system development.
  • The long-term consequences of prenatal hypothyroidism on auditory function are not fully understood.

Purpose of the Study:

  • To investigate the long-term effects of prenatal hypothyroidism on the auditory function of adult rat offspring.
  • To assess cochlear and neural pathway integrity following perinatal hypothyroidism.

Main Methods:

  • Pregnant rats received methimazole (MMI) from gestational day 9 to postnatal day 15.
  • Offspring underwent tympanometry, distortion product otoacoustic emissions (DPOAE), and auditory brainstem response (ABR) testing at multiple postnatal ages.
  • Evaluations included middle ear function, outer hair cell function, and central auditory pathway integrity.

Main Results:

  • No middle ear dysfunction was observed, though compliance was lower in the MMI-treated group.
  • Distortion product otoacoustic emissions (DPOAE) indicated absent outer hair cell function.
  • Auditory brainstem response (ABR) showed intact central auditory pathways, but hearing loss was evident via higher electrophysiological thresholds.

Conclusions:

  • Prenatal hypothyroidism induces irreversible damage to cochlear function in offspring.
  • The study highlights the critical role of thyroid hormones in auditory system maturation and function.
  • Hearing loss in offspring is characterized by cochlear damage rather than central auditory pathway dysfunction.

Keywords:
cochleacongenital hypothyroidismhearing loss

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