Acute changes in cochlear potentials due to cisplatin

Area of Science:

• Ototoxicity research
• Auditory neuroscience
• Inner ear physiology

Background:

• Cisplatin is a common chemotherapy agent with known ototoxic side effects.
• The precise early mechanisms of cisplatin-induced hearing loss are not fully understood.
• Hair cells and stria vascularis are critical for auditory function and are potential targets of ototoxicity.

Purpose of the Study:

• To investigate the early effects of cisplatin on hair cells and the stria vascularis.
• To simultaneously observe the impact of cisplatin on endocochlear potential (EP) and cochlear microphonics (CM).
• To correlate electrophysiological changes with morphological alterations in the cochlea.

Main Methods:

• Adult chinchillas were treated with topical cisplatin or saline on the round window.
• Endocochlear potential (EP) and cochlear microphonics (CM) were recorded for 12-14 hours.
• Scanning electron microscopy was used to assess morphological changes in cochlear structures.

Main Results:

• A profound reduction in both EP and CM amplitudes was observed within 12-14 hours.
• A strong correlation existed between EP and CM amplitude reductions.
• Minimal outer hair cell degeneration was noted at 12-14 hours, despite significant functional decline.

Conclusions:

• Early cisplatin ototoxicity primarily affects cochlear function through stria vascularis alterations, leading to EP reduction.
• Subsequent hair cell damage contributes to later-stage cochlear dysfunction.
• These findings highlight the stria vascularis as an early target in cisplatin-induced ototoxicity.