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Updated: May 6, 2026
Cochlear Implant Surgery and Electrically-evoked Auditory Brainstem Response Recordings in C57BL/6 Mice
Published on: January 9, 2019
D-methionine pre-loading reduces both noise-induced permanent threshold shift and outer hair cell loss in the
Alexander D Claussen1, Daniel J Fox, Xin C Yu
1* Department of Surgery, Southern Illinois University School of Medicine , Springfield , USA.
Objective:
This study tested multiple dosing epochs of pre-loaded D-methionine (D-met) for otoprotection from noise-induced hearing loss (NIHL).
Design:
Auditory brainstem response (ABR) thresholds were measured at baseline, 1 day, and 21 days following a 6-hour 105 dB sound pressure level (SPL) octave band noise (OBN) exposure. Outer hair cell (OHC) counts were measured after day 21 sacrifice.
Study Sample:
Three groups of five Chinchillas laniger each were given a 2-day regimen comprising five doses of D-met (200 mg/kg/dose) intraperitoneally (IP) starting 2, 2.5, or 3 days prior to noise exposure. A control group (n = 5) received five doses of equivalent volume saline IP starting 2.5 days prior to noise exposure.
Results:
ABR threshold shifts from baseline to day-21 post-noise exposure were reduced in all D-met groups versus controls, reaching significance (p < 0.05) in the 3-day group. D-met groups showed reduced OHC loss relative to controls at day-21 post-noise exposure, reaching significance (p < 0.05) at all frequency regions in the 3-day group and at the 2, 4, and 8 kHz frequency regions in the 2.5-day group.
Conclusions:
D-met administration in advance of noise-exposure, without further administration, significantly protects from noise-induced ABR threshold shift and OHC loss.
