title: Alterations in the intrauterine environment by glucocorticoids modifies the developmental programme of the auditory system.
abstract: Prenatal exposure to excessive glucocorticoids alters the programming of the metabolic and endocrine balance of various organs, including the nervous system. In the present study, prenatal glucocorticoid treatment was shown to increase the susceptibility of the inner ear to acoustic noise trauma in adult life. Acute auditory brainstem response thresholds were not different between the age-matched groups. However, when measured at 48 h and 4 weeks postexposure, the dexamethasone (DEX)-treated rats showed little or no recovery from the trauma. In contrast, normal rats showed a significant amount of recovery by 48 h postexposure and continued to show further recovery over 4 weeks. In addition, acoustic trauma resulted in a massive outer hair cell loss in the DEX rats compared to minor loss in the normal rats. To determine whether oxidative stress plays a role in the recovery phase of acoustic trauma, the free radical scavenger PBN (100 mg/kg) was administered before, during and several times after noise exposure. PBN treatment significantly reduced the physiological and morphological cochlear differences which were observed between DEX and control rats after acoustic trauma. These data support the hypothesis that alterations in the intrauterine environment may modify the developmental programme of the cochlea, inducing dysfunction later in adult life. Excessive prenatal exposure to dexamethasone decreased the potential for recovery of the cochlea to oxidative stress induced by acoustic trauma; this decreased recovery potential can be counteracted by treatment with antioxidants.
authors.affiliation: Department of Physiology and Pharmacology, Huddinge University Hospital, Karolinska Institutet, S-171 77 Stockholm, Sweden. Barbara.Canlon@fyfa.ki.se
authors.forename: Barbara
authors.initials: B
authors.lastname: Canlon
authors.forename: Susan
authors.initials: S
authors.lastname: Erichsen
authors.forename: Elin
authors.initials: E
authors.lastname: Nemlander
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Amzad
authors.initials: A
authors.lastname: Hossain
authors.forename: Gianni
authors.initials: G
authors.lastname: Celsi
authors.forename: Sandra
authors.initials: S
authors.lastname: Ceccatelli
mesh_terms: D000818:Animals; D017209:Apoptosis; D001309:Auditory Threshold; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism; D005938:Glucocorticoids / Q000494:pharmacology*; D018072:Hair Cells, Auditory, Outer / Q000002:abnormalities* / Q000378:metabolism / Q000473:pathology; D034381:Hearing Loss / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D009622:Noise / Q000009:adverse effects; D018384:Oxidative Stress / Q000187:drug effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016166:Free Radical Scavengers; D005938:Glucocorticoids; D003907:Dexamethasone