No evidence for enhanced noise induced hearing loss after prenatal stress or dexamethasone.
It was recently implied that prenatal stress and fetal exposure to glucocorticoids may interfere with hearing ability and noise induced hearing loss in adulthood. In the present study pregnant Wistar rats were stressed during gestation by Chronic Mild Stress (CMS, a variable schedule of different stressors) or by dexamethasone (a synthetic glucocorticoid, i.e. a pharmacological stressor). At birth, but not at weaning, the dexamethasone offspring exhibited significantly decreased body weight compared to both control offspring and progeny from dams exposed to CMS during pregnancy. As adults, male offspring were exposed to 105 dB sound pressure level (SPL) wide band noise either continuously for eight hours or for two hours per day on three consecutive days. Oto-acoustic emissions and auditory brainstem responses were recorded before and after exposure to noise. Neither prenatal chronic stress nor prenatal dexamethasone exposure was associated with significantly enhanced noise induced hearing loss compared to controls, and these results were consistent in both subsets of animals. Our data do not support previous reports that prenatal exposure to mild stress nor to dexamethasone is detrimental to the hearing organ per se. However, hearing may be modulated by prenatal stressors under certain circumstances, of which the timing and degree are probably the most important.
Hougaard
Karin S
KS
National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark. ksh@nrcwe.dk
Barrenäs
Marie-Louise
ML
Kristiansen
Gitte B
GB
Lund
Søren P
SP
D000161:Acoustic Stimulation; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D003907:Dexamethasone / Q000009:adverse effects*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D005938:Glucocorticoids / Q000009:adverse effects*; D034381:Hearing Loss / Q000209:etiology*; D006320:Hearing Tests; D009622:Noise / Q000009:adverse effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000209:etiology*; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D013312:Stress, Physiological / Q000150:complications* / Q000209:etiology