Measurement of DPOAE after ischemia/reperfusion injury of the cochlea in gerbils

• Published in: Neuroscience letters Vol. 467; no. 2; pp. 135 - 138
• Main Authors: Watanabe, Futoshi, Hakuba, Nobuhiro, Gyo, Kiyofumi
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 25.12.2009; Elsevier
• Subjects: Action potential; Action Potentials; Animals; Biological and medical sciences; Cochlea - blood supply; Cochlea - pathology; Cochlea - physiopathology; Compound action potential; Distortion product otoacoustic emission; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Fundamental and applied biological sciences. Psychology; Gerbillinae; Hair Cells, Auditory, Inner - pathology; Hair Cells, Auditory, Outer - pathology; Ischemia/reperfusion injury; Organ of Corti; Otoacoustic Emissions, Spontaneous; Reperfusion Injury - pathology; Reperfusion Injury - physiopathology; Vertebrates: nervous system and sense organs; Ischemia/reperfusion injury; Compound action potential; Organ of Corti; Distortion product otoacoustic emission; Corti organ; Otoacoustic emission; Rodentia; Electrophysiology; Action potential; Inner ear; Organ of hearing; Vertebrata; Mammalia; Animal; Cochlea; Lesion; Gerbil
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2009.10.023

The effects on distortion product otoacoustic emissions (DPOAEs) during the late phase of ischemia/reperfusion injury in the cochlea were studied. Ischemia/reperfusion injury was induced in a gerbil model by occluding both vertebral arteries for 15 min. Hearing was assessed by recording compound action potentials (CAPs) before, during, and 7 days after ischemia. The histological changes in the hair cells were evaluated in specimens stained with rhodamine-phalloidin and Hoechst 33342. The average increase in CAP threshold 7 days after ischemia was 16.3 ± 8.0 dB at 8 kHz. In contrast, interruption of the blood supply to the cochlea decreased the DPOAE amplitudes to the noise floor; this usually recovered to the same level as that seen under pre-ischemic conditions 7 days after ischemia. Histologically, the mean respective losses of inner and outer hair cells (IHCs and OHCs, respectively) of the inner ear were 26.5% and 3.3% in the basal turn, respectively. These results indicate that in gerbils OHCs are tolerant to ischemia/reperfusion injury pathologically and physiologically because DPOAE is closely related to the active process of OHCs and is a useful test to examine OHC function.