Expression of pro-inflammatory cytokines in the auditory cortex of rats with salicylate-induced Tinnitus

Abstract

Tinnitus often results in severe psychological distress. The present study hypothesized that tinnitus acts as a chronic stressor and induces dysregulation of the production of cytokines. The gap pre-pulse inhibition of acoustic startle paradigm was applied to test tinnitus-like behavior in rats. Following this, the mRNA and protein expression levels of interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-6 and N-methyl D-aspartate receptor subunit 2A (NR2A) were measured in rats subjected to acute and chronic salicylate treatment, using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. The gap prepulse inhibition of acoustic startle paradigm detected the tinnitus-like behavior of rats. The expression of TNF-α and NR2A genes were increased in the auditory cortex (AC) following long-term administration of salicylate, whereas the expression of IFN-γ genes decreased; however, the mRNA levels reversed back to normal baseline 14 days following the cease of salicylate administration. IL-6 gene expression, however, was not fundamentally altered by salicylate treatment. The data demonstrated that chronic salicylate administration induces tinnitus, in part, via dysregulation of cytokines and specific membrane receptors in the AC.