Blockade of HMGB1 by pretreatment with anti-HMGB1 antibodies diminished the noise-induced increase in RNS level and inflammation in the cochlea. Mice were treated intraperitoneally with anti-HMGB1 antibodies or saline at 30 min prior to noise exposure. Samples of cochlear homogenates or sections were collected 4 days after noise exposure. Representative immunohistochemical staining (peroxidase/DAB (brown color) for (A) nitrotyrosine, (B) iNOS, and (C) ICAM-1 in the cochlea (n = 4 [refers to 4 cochleae from 4 different animals]). Sections were counterstained with hematoxylin. I, II, III, IV = classification of spiral-ligament fibrocytes. Scale bars = 50 μm.