Signal pathway associated with hair cell death in cochlea following exposure to intense impulse noise
- VernacularTitle:强脉冲噪声暴露后耳蜗毛细胞死亡的信号通路
- Author:
Weiping YANG
;
Bohua HU
;
Henderson DONALD
- Publication Type:Journal Article
- Keywords:
noise;
hair cells;
apoptosis;
signal transduction;
caspase
- From:
Medical Journal of Chinese People's Liberation Army
1982;0(01):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective Apoptosis and necrosis are two forms of hair cell death in cochlea following exposure to intense impulse noise.The present study was designed to examine the activity of caspase-3,caspase-8 and caspase-9 in the basilar membrane of cochlea,and investigate the cellular signal pathway associated with noise-induced hair cell death in cochlea.Methods Twenty-seven adult chinchillas were used in present study.The animals were randomly assigned into test group(no.15) and control group(no.12).The animals in test group were exposed to noise for the detection of the activity of caspase-3,caspase-8 and caspase-9,respectively,each with 5 animals.Animals in control group were not exposed to noise.Chinchillas were exposed to impulse noise at 155 dB peak sound pressure level(pSPL) for 75 times.Two hours after noise exposure,both cochleae were perfused with approximately 30?l of freshly prepared solution containing one of the three caspases(caspase-3,-8 and-9) respectively using a micro-syringe.One hour after perfusion,the animals were sacrificed and the cochleae were harvested.The Corti organs were double stained with propidium iodide(PI),and a DNA intercalating fluorescent probe was used to visualize the morphologic viability of hair cell nuclei.All the specimens were observed with a fluorescence microscope.Results The normal cochlea did not exhibit green fluorescence for any of the three caspases in Corti organ.Strong caspase-3,-8 and-9 green fluorescence appeared in the outer hair cells with condensed or fragmented nuclei,a sign of apoptosis,whereas no fluorescence was observed for any of the three caspases in the swollen outer hair cell nuclei,a sign of necrosis,in the cochleae exposed to intense impulse noise.Conclusion It is indicated that caspase-9 is involved in the intrinsic and caspase-8 involved in the extrinsic apoptotic pathway which occur simultaneously in apoptotic outer hair cells.No caspase activation occurs in necrotic outer hair cell in the cochlea following exposure to intense impulse noise.
