Retinoic acid applied after noise exposure can recover the noise-induced hearing loss in mice.
CONCLUSIONS
The early post-exposure treatment with All-trans retinoic acid (ATRA) can reduce hair cell loss and hearing deterioration in mice in which permanent threshold shift has been induced.


OBJECTIVE
One of the mechanism by which intense noise induces apoptosis of cochlea hair cells is the C-Jun NH(2)-terminal kinase (JNK) pathway. ATRA is a potent inhibitor of activator protein 1, a transcription factor of the JNK pathway. In this study we evaluated that the effect of post-exposure treatment of ATRA on noise-induced hearing loss and aimed to determine a time window for effective post-exposure treatment of ATRA.


METHODS
All mice were exposed to white noise for 3 h per day for three consecutive days and induced permanent threshold shift. The treatment groups fed with ATRA from 1 h, one day, two days, and three days after noise exposure for five days were compared with mice fed with same dosage of sesame oil. We measured the threshold shifts of hearing and survival rates of hair cells on the cytocochleogram.


RESULTS
Mice fed with ATRA beginning within two days after noise had less threshold shifts and more hair cell survivals than mice fed with sesame oil.
Shim
Hyun Joon
HJ
Department of Otolaryngology, Eulji Hospital, Eulji University, College of Medicine, Seoul, Korea.
Kang
Hun Hee
HH
Ahn
Joong Ho
JH
Chung
Jong Woo
JW
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D004195:Disease Models, Animal; D016057:Evoked Potentials, Auditory, Brain Stem; D006198:Hair Cells, Auditory / Q000473:pathology; D006317:Hearing Loss, Noise-Induced / Q000188:drug therapy*; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D008807:Mice, Inbred BALB C; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors; D014212:Tretinoin / Q000494:pharmacology*
D018808:Transcription Factor AP-1; D014212:Tretinoin; D048031:JNK Mitogen-Activated Protein Kinases