AIF and EndoG in noise-induced hearing loss.

Apoptosis plays a critical role in neuronal cell death, including sensory cell death in noise-induced hearing loss. The purpose of this study is to investigate the role of a caspase-independent apoptotic pathway, involving apoptosis-inducing factor (AIF) and endonuclease G (EndoG) in cell death in the inner ear after intense noise exposure (120 dB SPL, 4 kHz OBN, 5 h). EndoG was translocated to the nucleus after noise trauma, whereas immunostaining for AIF was expressed only in the cytosol. These findings indicate that EndoG is a factor in noise-induced caspase-independent apoptosis. In contrast, AIF may not be involved in cell death, but act as a redox factor in response to noise-induced oxidant stress.