Posted on January 26, 2008 by
Acta Otolaryngol Suppl. 2007 Oct;(558):73-7.
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Hypoxic changes in the central nervous system of noise-exposed
Kim YJ, Kang HH, Ahn JH, Chung JW.
Department of Otolaryngology, Pundang Jaesang Hospital, DaeJin
Medical Center, Seongnam City, Kyunggi Do, Korea.
CONCLUSION: After a noise-induced transient threshold shift,
hypoxia occurred in the central nervous system, especially in the
auditory cortex, the hippocampus, and the inferior colliculus.
OBJECTIVES: Noise-induced inner ear hypoxia was shown by measurement
of an increase in hypoxia-inducible factor-1 alpha, which is
expressed? in the nucleus under hypoxic conditions. This study uses
pimonidazole to localize site-specific hypoxic changes occurring in
the mouse central auditory pathway during noise-induced auditory
threshold shift. METHOD: BALB/c hybrid mice with normal hearing were
exposed to 122 dB SPL white noise for 3 h. Immediately after exposure
to the noise, and 7 d after noise exposure, the brains of mice were
collected. Brains were cryosectioned into slices 15 microm thick and
examined by immunofluorescence after staining with pimonidazole HCl.
RESULTS: After 3 h of exposure to 120 dB SPL noise, the hearing
thresholds of mice decreased to 51.1+/-8.6 dB SPL (n =14), but hearing
recovered in 7 d. After noise exposure, pimonidazole signal increased
in the auditory cortex, the hippocampus, and the inferior colliculus.
The pimonidazole signal remained elevated after 7 d. In control mice,
pimonidazole did not stain any brain region.
* Research Support, Non-U.S. Gov’t
PMID: 17882574 [PubMed – indexed for MEDLINE]