Molecular remodeling of the central auditory pathway in tinnitus revealed by RNA sequencing

Tinnitus is a complex neurological condition affecting 10-15% of adults worldwide, characterized by phantom auditory perception without external sound sources. While traditional investigations have focused on discrete auditory structures, emerging evidence suggests tinnitus involves broader alterations across central auditory regions.

This study employed transcriptomic analysis to investigate molecular mechanisms underlying salicylate-induced tinnitus across multiple brain regions simultaneously.

Male C57BL/6 N mice received daily intraperitoneal injections of sodium salicylate (350 mg/kg) for five consecutive days to induce tinnitus-like behavior, assessed using gap-prepulse inhibition of acoustic startle reflex. RNA sequencing was performed on auditory cortex, inferior colliculus, and cochlear nucleus tissues. Differential gene expression analysis, weighted gene co-expression network analysis, and functional annotation were conducted to identify shared molecular signatures and pathways across auditory centers.

Principal component analysis revealed region-specific transcriptomic changes following salicylate treatment. Differential gene expression analysis identified Depp1 and Angptl4 as consistently upregulated genes across multiple brain regions, particularly within the inferior colliculus and cochlear nucleus. Weighted gene co-expression network analysis revealed a 215-gene module increased across all auditory regions in tinnitus mice, with functional annotation indicating enrichment for vasculature-related biological processes. Depp1 emerged as a central hub gene linking oxidative stress responses to autophagy mechanisms.

This study shows that tinnitus pathology involves not only neuronal hyperactivity but also oxidative stress, neuroinflammation, and autophagy in the central auditory pathway. Depp1 acts as a molecular hub linking redox imbalance to cellular clearance, highlighting its potential as a therapeutic target and offering new insights for intervention.