Effect of stress on cochlear glucocorticoid protein: acoustic stress

Levels of glucocorticoid (GR) receptor protein were determined by a quantitative enzyme-linked immunosorbent assay (ELISA) technique in inner ear tissue of rats exposed daily to 85 dB SPL white noise for 4 hours on 3 consecutive days. GR levels in spiral ligament and organ of Corti tissues were detected using a monoclonal antibody to the GR receptor, BuGR2. A non-significant 13% decrease in GR levels of spiral ligament tissues was observed in the noise exposed animals relative to untreated animals. A statistically significant decrease of 27% in GR protein levels was seen in the organ of Corti region (P < 0.03), however. There was a concomitant increase of serum corticosterone levels (P < 0.03) in noise exposed animals as opposed to those of controls. These results indicate a tissue specific response of GR receptor to acoustic stress. Inner ear GR protein therefore may be a useful marker in determining the effect of stress on the inner ear. Finally, such data may be applicable to support the hypothesis that stress is an etiological agent in Ménière's disease.