噪声暴露后耳蜗凋亡与坏死毛细胞琥珀酸脱氢酶活性的变化

目的揭示噪声暴露后耳蜗凋亡、坏死毛细胞线粒体功能的变化。方法将灰鼠暴露于155dBSPL的脉冲噪声75次，噪声暴露后5h解剖取双侧耳蜗。采用琥珀酸脱氢酶（SuccinateDehydrogenase，SDH）染色法进行耳蜗基底膜细胞线粒体染色，细胞核DNA荧光染料碘化丙啶（propidiumiodide，PI）双重染色耳蜗基底膜，以未受噪声暴露动物为对照，显微镜下观察噪声暴露后耳蜗基底膜核固缩和核肿胀毛细胞琥珀酸脱氢酶染色的变化。结果噪声暴露损伤区的耳蜗外毛细胞SDH着色变浅．蓝色颗粒物存在于PI标记固缩的耳蜗毛细胞核周围，而肿胀的毛细胞核周围缺少SDH阳性染色物。结论强脉冲噪声暴露后，凋亡的耳蜗外毛细胞依然存在不同程度的线粒体功能，而坏死的外毛细胞线粒体功能受损严重。

The changes of succinate dehydrogenase activity in the apoptotic and necrotic outer hair cells following impulse noise exposure

Objective To examine the changes of mitochondrial function in the noise-induced apoptotic and necrotic outer hair cells(OHCs). Methods Chinchillas were exposed to 75 pairs of impulse noise(1 second interval between each pair) at 155 dB pSPL. Five hours after the noise exposure, the cochleae were harvested. Mitochondria energetic function, succinate dehydrogenase(SDH) activity, in the hair cells(HCs) of cochleae was evaluated with a colorimetric assay using blue tetrazolium(NBT) monosodium salt. The SDH-labeled organs of Corti were double stained with propidium iodide(PI), a DNA intercalating fluorescent probe used to visualize the morphologic viability of hair cell nuclei. All the specimens were observed with a microscope with bright field for SDH staining or epifluorescence illumination for PI labeling. Results SDH staining appears around the OHCs showing nuclear condensation, a sign of apoptosis. The OHCs with the nuclear swelling, a sign of necrosis, lack SDH staining. Conclusion The result of the study indicates that energetic function of mitochondria is preserved in the course of the apoptotic process, but seriously damaged in the course of the necrotic process.