Prestin up-regulation in chronic salicylate (aspirin) administration: an implication of functional dependence of prestin expression.

Salicylate (aspirin) can reversibly eliminate outer hair cell (OHC) electromotility to induce hearing loss. Prestin is the OHC electromotility motor protein. Here we report that, consistency with increase in distortion product otoacoustic emission, long-term administration of salicylate can increase prestin expression and OHC electromotility. The prestin expression at the mRNA and protein levels was increased by three- to four-fold. In contrast to the acute inhibition, the OHC electromotility associated charge density was also increased by 18%. This incremental increase was reversible. After cessation of salicylate administration, the prestin expression returned to normal. We also found that long-term administration of salicylate did not alter cyclooxygenase (Cox) II expression but down-regulated NF-kappaB and increased nuclear transcription factors c-fos and egr-1. The data suggest that prestin expression in vivo is dynamically up-regulated to increase OHC electromotility in long-term administration of salicylate via the Cox-II-independent pathways.