- Published on 14 October 2013
Scientists at the Oregon Hearing Research Center at the Oregon Health and Science University (USA) carried out a new study in mice to assess the molecular mechanisms underlying noise-induced hearing loss, with associated tinnitus and sound hypersensitivity.
The researchers studied three groups of mice aged about 6 to 8 weeks. The first group was exposed to broadband noise at 120 dB in a sound exposure booth for 3 hours on two consecutive days. The second group was given single-dose injections of pigment epithelium-derived factor (PEDF) before exposure, and the third served as a control group. The study focused on perivascular-resident macrophage-like melanocytes (PVM/Ms), thought to maintain barrier integrity in the intrastrial fluid/blood barrier of the cochlea. These cells secrete PEDF and play a role in normal hearing.
Results showed that most PVM/Ms in control tissue had a characteristic branched morphology, with maximum coverage of the capillary wall. In contrast, cell morphology was markedly changed in the noise-exposed group, with reduced branching and withdrawal of ramifications. PEDF was found to be significantly down-regulated by noise. In the PEDF-treated group, application of the compound was found to provide significant protection against noise-related deterioration in barrier integrity.
Based on these findings, PEDF-related improvement in hearing outcomes, after noise exposure, points to a possible new approach for treating noise-induced hearing loss.Source: Science World Report; Zhang F, et al. Perivascular macrophage-like melanocyte responsiveness to acoustic trauma--a salient feature of strial barrier associated hearing loss. FASEB Journal 2013 Sep;27(9):3730-40.