Effects of mitochondrial energy-conversion efficiency on controlling the initiation and execution of the apoptotic process in outer hair cells of cochlea following noise exposure
- VernacularTitle:线粒体能量转换功能在噪声诱导耳蜗毛细胞凋亡启动和进程中的作用
- Author:
Weiping YANG
;
Bohua HU
;
Henderson DONALD
- Publication Type:Journal Article
- Keywords:
mitochondria;
apoptosis;
noise;
hair cells;
cochlea
- From:
Medical Journal of Chinese People's Liberation Army
2001;0(08):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To examine the role of mitochondrial energy-conversion efficiency in regulating the initiation and execution of the apoptotic process in outer hair cells(OHCs)of cochlea following exposure to intense noise.Methods Seventeen adult chinchillas were used in present study.The animals were randomly assigned to one of the two groups,12 animals were exposed to noise and the remaining 5 animals without exposure to noise served as normal control.For all the animals,3-nitropropionic acid solution(3-NP,50mmol/L),an irreversible inhibitor of succinate dehydrogenase(SDH),was dropped onto the round window of the cochlea of the right ear using a micro-syringe to inhibit the mitochondrial energy production,to serve as the test ear.Artificial perilymph solution(AP)was dropped onto the round window of the cochlea of the left ear to serve as the control ear.16h after application of 3-NP and AP,the animals were exposed to 75 pairs of impulse noise at 155 dB pSPL.The cochleae were harvested 2h after the noise exposure.The cochlear basilar membrane was stained with propidium iodide(PI),a DNA intercalating fluorescent probe used to visualize the morphologic viability of hair cell nuclei.All the specimens were examined with a fluorescence microscope.Results In the 3-NP-treated cochlea,medium degree of nuclear condensation of OHCs appeared to be the dominant nuclear pathology,and only a few OHCs showed nuclear fragmentation in the damaged area of the cochlea.In contrast,the AP-treated control ear exhibited a large quantity of nuclear fragments,and a small quantity of medium degree of nuclear condensation.Conclusion The present study indicates that mitochondrial energy-conversion function plays an important role in regulating the apoptotic process.Disruption of the mitochondrial energy can not deter the apoptotic process from initiation,but can slow down the pace of apoptotic progression in outer hair cells of the cochlea following exposure to intense noise.
