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Updated: Jun 19, 2026
The Mouse Round-window Approach for Ototoxic Agent Delivery: A Rapid and Reliable Technique for Inducing Cochlear Cell Degeneration
Published on: November 26, 2015
Direct drug application to the round window: a comparative study of ototoxicity in rats
Silvia Murillo-Cuesta1, Fernando García-Alcántara, Elena Vacas
1Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, Madrid, Spain.
Objective:
To assess the validity of inducing ototoxicity in rats by applying a sponge soaked in kanamycin and furosemide on the round window.
Study Design:
Basic, randomized, nonblind experimental study.
Setting:
Animal models of cochlear damage and reliable methods of local drug delivery are fundamental to study hearing loss and to design new therapies.
Subjects And Methods:
Four experimental groups of six Wistar rats with different methods of drug administration were used: (1) injection of subcutaneous kanamycin (400 mg/kg) and intravenous furosemide (100 mg/kg); (2) local application of a sponge soaked in saline close to the round window; (3) animals for which the sponge was soaked in a solution containing kanamycin (200 mg/mL) and furosemide (50 mg/mL); and (4) sham-operated rats. The tympanic bulla was exposed using a ventral approach, and a bullostomy was performed to visualize the round window membrane. Cochlear function was assessed by measuring the auditory brainstem response, and hearing thresholds in response to click and tone burst stimuli were determined as peak and interpeak latencies. At the end of the study, cochlear histology was analyzed.
Results:
Systemic administration of kanamycin and furosemide induced profound hearing loss and severe hair cell damage. Local delivery of these ototoxic drugs caused comparable damage but avoided the systemic side effects of the drug. Sham-operated and saline control animals did not experience functional alterations.
Conclusion:
Situating a sponge soaked in kanamycin and furosemide on the round window membrane through the ventral approach is a reliable method to provoke local ototoxicity in rats.
Insights
This study demonstrates that applying a sponge soaked in kanamycin and furosemide to the round window in rats reliably induces local ototoxicity, causing hearing loss and hair cell damage without systemic side effects.
Area of Science:
- Ototoxicity research
- Auditory neuroscience
- Drug delivery systems
Background:
- Animal models are crucial for understanding hearing loss and developing new therapies.
- Reliable local drug delivery methods are needed for cochlear research.
Purpose of the Study:
- To evaluate the effectiveness of inducing ototoxicity in rats using a round window sponge soaked in kanamycin and furosemide.
- To establish a reproducible method for local cochlear drug delivery.
Main Methods:
- Wistar rats were divided into four groups: systemic ototoxic drug administration, saline sponge control, local ototoxic drug sponge application, and sham operation.
- Cochlear function was assessed using auditory brainstem response (ABR) testing.
- Histological analysis of cochlear hair cells was performed.
Main Results:
- Systemic kanamycin and furosemide caused significant hearing loss and hair cell damage.
- Local application of the ototoxic drug-soaked sponge resulted in comparable cochlear damage.
- Local delivery mitigated systemic side effects observed with systemic administration.
- Control groups showed no functional or histological changes.
Conclusions:
- Applying a sponge soaked in kanamycin and furosemide to the round window via a ventral approach is a validated and reliable method for inducing localized ototoxicity in rats.
- This technique offers a controlled approach to studying cochlear damage and evaluating potential therapeutic interventions.
