J Korean Med Sci.  2020 Apr;35(13):e81. 10.3346/jkms.2020.35.e81.

Objective Verification of Acute Tinnitus and Validation of Efficacy of Systemic Steroids in Rats

Affiliations
  • 1Department of Otolaryngology, Ajou University School of Medicine, Suwon, Korea.
  • 2Department of Biomedical Sciences, BK21 Plus Research Center for Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Korea.
  • 3Department of Otorhinolaryngology Head and Neck Surgery, Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, Korea.
  • 4Department of Biomedical Engineering, College of Medicine, Dankook University, Cheonan, Korea.

Abstract

Background
This study was performed to identify acute tinnitus and evaluate the efficacy of steroids for noise-induced acute tinnitus by measuring the gap-prepulse inhibition of the acoustic startle (GPIAS) value in an animal model.
Methods
Nineteen rats (the noise group [n = 7] and the noise + dexamethasone [DEX] group [n = 12]) were exposed to narrow-band noise centered at 16 kHz from a sound generator for 4 hours. The noise + DEX group received intraperitoneal steroid administration daily for 5 days (1.5 mg/kg/day) after completing noise exposure. Auditory brainstem response and GPIAS value were measured just prior to, and 1 day after noise exposure and on days 1 and 10 days after completing steroid administration. The changes in cochlear structure were evaluated by histological analysis.
Results
The threshold shift was checked 1 and 10 days after intraperitoneal steroid injection, and no differences in threshold shift were observed between the two groups in each frequency except for 32 kHz 1 day after steroid injection. The mean GPIAS value in the noise + DEX group (36.4% ± 14.1%) was significantly higher than that in the noise group (16.4% ± 18.8%) 10 days after intraperitoneal steroid administration (P = 0.017). There were no pathological changes associated with noise trauma in the two groups as determined on hematoxylin and eosin and immunohistochemical staining.
Conclusion
An acute tinnitus model with minimal structural changes by noise exposure was set up, and used to verify tinnitus objectively by measuring the GPIAS value. Steroid therapy for control of tinnitus was validated in this animal model.

Keyword

Tinnitus; GPIAS; Auditory Brainstem Response; Dexamethasone; Noise-Induced Hearing Loss
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