The effect of isoflurane, halothane and pentobarbital on noise-induced hearing loss in mice.
BACKGROUND
Ear surgery using mastoid drills can lead to noise-induced hearing loss (NIHL). We investigated whether inhaled anesthetics or pentobarbital could have protective effects on NIHL in mice.


METHODS
Mice were exposed to broad band white noise for 3 h per day for 3 consecutive days, with or without anesthesia, using halothane, isoflurane, or pentobarbital. The hearing level of each mouse was analyzed before exposure, and 1 day, 1, 2, and 3 Wk, and 1 mo after noise exposure by measuring auditory brainstem response thresholds. At 1 Wk after noise exposure, the organ of Corti was stained with a fluorescent isothiocyanate-conjugated phalloidin probe and a TUNEL kit.


RESULTS
In the unanesthetized control group, the hearing threshold increased to 77.5 +/- 8.0 dB hearing level (HL) after noise stimulation. In the pentobarbital, isoflurane, and halothane groups, hearing threshold increased to 62.5 +/- 6.3 dB HL, 45.5 +/- 9.8 dB HL, and 39.3 +/- 6.2 dB HL, respectively, with all anesthetized groups of mice showing significantly preserved hearing compared with the control group (P < 0.05). But, in mice anesthetized with pentobarbital, hearing loss was more severe than in those treated with the inhaled anesthetics (P < 0.05). Hair cell survival was reduced in unanesthetized control mice and somewhat reduced in pentobarbital-treated mice, but largely unaffected in mice treated with inhaled anesthetics.


CONCLUSIONS
These findings indicate that, while halothane, isoflurane and pentobarbital could protect mice against NIHL and hair cell damage, inhaled anesthetics were more effective.
Chung
Jong Woo
JW
Department of Otolaryngology, Asan Medical Center, College of Medicine, University of Ulsan, Songpa-Gu, Seoul, Korea.
Ahn
Joong Ho
JH
Kim
Jong Yang
JY
Lee
Hyun Jung
HJ
Kang
Hun Hee
HH
Lee
Yoon Kyung
YK
Kim
Joung Uk
JU
Koo
Seung-Woo
SW
D000818:Animals; D006221:Halothane / Q000494:pharmacology / Q000627:therapeutic use*; D006309:Hearing / Q000187:drug effects / Q000502:physiology; D006317:Hearing Loss, Noise-Induced / Q000188:drug therapy / Q000517:prevention & control*; D007530:Isoflurane / Q000494:pharmacology / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D009925:Organ of Corti / Q000187:drug effects / Q000502:physiology; D010424:Pentobarbital / Q000494:pharmacology / Q000627:therapeutic use*
D007530:Isoflurane; D010424:Pentobarbital; D006221:Halothane