[Role of caspase 12 in apoptosis of cochlea induced by intense noise in guinea pigs].
OBJECTIVE
To investigate the relationship between caspase 12 activation and endoplasmic reticulum stress mediated apoptosis of guinea pig cochlea cells induced by intense noise.


METHODS
Thirty-two guinea pigs were randomly divided into 4 groups. The guinea pigs in the experiment groups were exposed to 4 kHz narrow band noise at 120 dB SPL for 4 h. After the noise expose for 1, 4, 14 days of the experiment guinea pigs, auditory brainstem response (ABR) of the guinea pigs on experiment and control groups were tested before decapitated. Four guinea pig's cochleae of every group were taken to paraffin section, and the rest was extracted the total protein. Apoptosis was tested by terminal deoxynucleotidyl transferase (TDT)-mediated deoxyuridine triphosphate (d-UTP) nick and labeling method (TUNEL) and transmission electron microscopy. Expression of caspase 12, Bip/GRP78 was tested by immunohistochemistry and Western blot methods.


RESULTS
The observation by transmission electron microscopy showed the features characteristic of apoptotic cells in the Corti and SGC of 1d after the noise expose, but no in the control. There were higher expressions of Tunel-Positive cells in the OHC, SGC and SV of experiment groups, and there was significant differences compared with the control group (P < 0.01). Protein levels of Bip/GRP78 and caspase 12 were risen up after noise exposed, and there all were significant differences compared with the control group (P < 0.01).


CONCLUSIONS
Intense noise causes cochlea cell lesion by inducing apoptosis to result in and caspase 12 induced endoplasmic reticulum stress-related apoptosis plays an important role in the procedure of apoptosis.
Xue
Qiu-Hong
QH
Department of Otorhinolaryngology, Affiliated Hospital of Wuhan University of Science and Technology, Wuhan 430064, China. xueqh815@hotmail.com
Chen
Jia
J
Gong
Shu-Sheng
SS
He
Jian
J
Xie
Jing
J
Chen
Xiao-Lin
XL
D000818:Animals; D017209:Apoptosis; D053454:Caspase 12 / Q000378:metabolism*; D003051:Cochlea / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D016057:Evoked Potentials, Auditory, Brain Stem; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism / Q000473:pathology; D008297:Male; D009622:Noise / Q000009:adverse effects*
D053454:Caspase 12