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Free Radic Res. 2011 Oct;45(10):1162-72. doi: 10.3109/10715762.2011.605360. Epub 2011 Aug 10.

Effects of delayed and extended antioxidant treatment on acute acoustic trauma.

Author information

1
Audiology & Speech-Language Pathology & Research Institute of Biomimetic Sensory Control, College of Medical Sciences, Catholic University of Daegu, Kyungsansi, South Korea. cchoi@cu.ac.kr

Abstract

OBJECTIVE:

Hair cell death caused by acute acoustic trauma (AAT) reaches a secondary maximum at 7-10 days after noise exposure due to a second oxidative stress. Therefore, this study tested the effects of a combination of hydroxylated alpha-phenyl-tert-butylnitrone (4-OHPBN), N-acetyl-L-cysteine (NAC) and acetyl-L-carnitine (ALCAR) on AAT when the duration of treatment was extended over the period of 7-10 days after noise exposure as well as when the initial treatment was delayed 24 to 48 h after noise exposure.

METHODS:

Thirty chinchilla were exposed to a 105 dB octave-band noise centred at 4 kHz for 6 h and received the following treatments: (1) noise + saline (2-5) 4-OHPBN (20 mg/kg) + NAC (50 mg/kg) + ALCAR (20 mg/kg) intraperitoneally injected beginning 24 or 48 h after noise exposure twice daily for the next 2, 8 or 9 days. Auditory brainstem response (ABR) threshold shifts, outer hair cell (OHC) counts and organ of Corti immunohistochemistry were analyzed.

RESULTS:

The combination administration decreased ABR threshold shifts, inhibited OHC loss and reduced 4-hydroxynonenal (4-HNE) immunostaining. Significant decreases in the threshold shifts and reduction in OHC loss were observed with a shorter delay before starting treatment (24 h) and longer duration (9 days) treatment.

CONCLUSIONS:

These results demonstrate that the administration of antioxidant drugs extended up to 10 days after noise exposure can effectively treat AAT in a chinchilla model. This may provide significant and potentially clinically important information about the effective therapeutic window for AAT treatment.

PMID:
21756051
DOI:
10.3109/10715762.2011.605360
[Indexed for MEDLINE]

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