强噪声对耳蜗组织化学影响的研究

A HISTOLOGICAL STUDY OF THE INFLUENCE OF STRONG NOISE ON THE COCHLEA

本实验将豚鼠分为四组:一组为对照组,另三组为实验组。所有豚鼠实验前都作耳廓反射阈测试,分别暴露于150 dB、156 dB和162 dB声压级的强噪声场5分钟。噪声暴露毕,再作耳廓反射阈测试。然后斩头处死豚鼠,速取双侧颞骨,打开骨泡,暴露耳蜗,一耳作琥珀酸脱氢酶试验、一耳作糖原和核酸(RNA和DNA)试验。结果如下:150 dB组耳廓反射阈增高3.8 dB;156 dB组近半数豚鼠(12只耳)耳廓反射阈完全消失,其余(18只耳)耳廓反射阈增高35.6 dB;162 dB组几乎全部豚鼠(28只耳)耳廓反射阈完全消失。三组实验豚鼠琥珀酸脱氢酶和糖原都有类似变化。150dB组豚鼠耳蜗螺旋器毛细胞中,这两种物质较对照组轻度损失(++~+),而且从底部向顶部越加明显。156dB和162 dB组,各耳蜗圈螺旋器毛细胞琥珀酸脱氢酶和糖原,一致性明显损失(+~±)。三组豚鼠耳蜗螺旋器和螺旋神经节细胞核酸(RNA和DNA)都未见明显变化。本实验表明,随噪声声压级增高,听力损伤程度也越加严重。琥珀酸脱氢酶和糖原都是与能量代谢有密切关系的物质,因此可认为,噪声刺激的早期主要引起耳蜗能量代谢障碍。

Forty five guinea pigs were divided into four groups,three groups for experiments and one for control.The threshold of auricular reflex of these animals were tested before they were exposed to strong noise at different sound pressure levels(150 dB,156 dB or 162 dB)for five minutes respectively.After the exposure,the threshold of auricular reflex was again tested.The guinea pigs were then dicapitated and the bilateral temporal bones were taken out as quickly as possible.Histochemical reactions of succinic dehydrogenase for one ear and of glycogen and nucleic acid(RNA.DNA)for the other were done as soon as the cochlea was exposed.The results were as follows:The auricular reflex threshold of guinea pigs in the 150 dB-group increased 3.8 dB;in the 156 dB-group disappeared completely in 12 ears and increased 35.6 dB in 18 ears;and in the 162 dB-group,almost all of them(28 ears),completely disappeared.The changes of succinie dehydrogenase activity and glycogen content of hair cells in the Corti’s organ of the guinea pigs in the 150 dB-group reduced slightly than that in the control group.Their diffcrcnce was more pronounced from the basal turn to apex of the Corti’s organ.The succinic dchydrogenase activity and glycogen content in the hair cells of the Corti’s organ in each turn of the cochlea of the guinca pigs in the 156 dB and thc 162 dBgroups lost obviously,while there was no remarkable change of the content of nucleic acids(RNA,DNA)to be seen in the Corti’s organ and the spiral ganglion in the three groups.The result of this experiment indicates that with increasing of noise pressure levels,the loss of hearing is getting more serious.The histochemical changes of the succinic dehydrogenase activity and glycogen content suggest that the disturbance in energy metabolism is closely associated with the loss of hearing at the begining of strong noise stimulation.