Comparative observation of protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure.
OBJECTIVE
To explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure (BUP).


METHODS
The hearing thresholds of the guinea pigs were assessed with auditory brainstem responses (ABR). The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells (OHCs) loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection.


RESULTS
An important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa ( P<0.01). The rate of perforation of tympanic membrane reached 87.5% and that of total OHCs loss was 19.46% +/- 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection (P<0.01). All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug (P<0.01).


CONCLUSIONS
The earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.
Li
Chao-jun
CJ
Department of Otolaryngology-Head and Neck Surgery, Daping Hospital, Third Military Medical University, Chongqing 400042, China. dapinghearing@263.net
Zhu
Pei-fang
PF
Liu
Zhao-hua
ZH
Wang
Zheng-guo
ZG
Yang
Cheng
C
Chen
Hai-bin
HB
Ning
Xin
X
Zhou
Ji-hong
JH
Chen
Jian
J
D000818:Animals; D001309:Auditory Threshold; D001753:Blast Injuries / Q000517:prevention & control*; D004430:Ear Protective Devices; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism*; D011312:Pressure; D014432:Tympanic Membrane / Q000293:injuries*; D018058:Tympanic Membrane Perforation / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*