神经生长因子对豚鼠噪声性听力损伤的保护作用

Protective effects of nerve growth factor on noise induced hearing damage in guinea pigs

目的：探讨神经生长因子（ｎｅｒｖｅ ｇｒｏｗ ｔｈ ｆａｃｔｏｒ，ＮＧＦ）对噪声性听力损伤的保护作用。方法：以听阈、耳蜗酶组织化学检测等为指标， 观察豚鼠每天在１１５ ｄＢ（Ａ）稳态噪声连续６ ｄ 的暴露（４５ ｍ ｉｎ／ｄ）前，肌肉注射不同剂量的ＮＧＦ对豚鼠皮层声诱发电位、听毛细胞琥珀酸脱氢酶（ｓｕｃｃｉｎｉｃ ｄｅｈｙｄｒｏｇｅｎａｓｅ， ＳＤＨ）活性的影响。结果：Ａ［ＮＧＦ：１ ０００ ＢＵ／（ｋｇ·ｄ），ｉｍ ．］， Ｂ［ＮＧＦ：２ ０００ ＢＵ／（ｋｇ·ｄ），ｉｍ ．］和Ｃ［ＮＧＦ：３ ０００ ＢＵ／（ｋｇ·ｄ），ｉｍ ．］３ 个实验组动物听阈偏移幅度均小于对照组［生理盐水：１ ｍ ｌ／（ｋｇ·ｄ），ｉｍ ．］，相差非常显著；实验Ｂ，Ｃ两组动物在噪声暴露后第３天听阈已基本恢复，而对照组动物在噪声暴露后第６天仍有（１６．４３±６．９１） ｄＢ的阈移。３ 个实验组耳蜗毛细胞ＳＤＨ 活性减弱程度也比对照组明显为轻； 而实验Ｂ，Ｃ两组则无显著性差异，但它们又明显轻于实验Ａ 组。结论：ＮＧＦ能减轻噪声对耳蜗及神经的损害，对听觉功能具有明显的保护作用。

Objective: To study the protective effects of nerve growth factor(NGF) on noise induced hearing damage in guinea pigs. Methods: Guinea pigs were exposed to white noise of 115 dB(A) for 6 days intermittently (45 min/d). At different post exposure intervals, auditory thresholds were measured using auditory cortex evoked response to tone bursts. The activities of succinic dehydrogenase(SDH) of hair cells were examined with enzyme histochemical method. Results: The auditory threshold shifts in test group A [NGF: 1 000 BU/(kg·d),im.], B [NGF:2 000 BU/(kg·d),im.] and C [NGF:3 000 BU/(kg·d),im.] were significantly fewer than that in the control group [saline:1 ml/(kg·d),im.]. Threshold shifts almost recovered in group B and C 3 days after exposure; while a threshold shift of (16.43±6.91) dB was present 6 days after exposure in the control group. The SDH activities within hair cells were less diminished in the test group than that in the control. The extent of diminished SDH activities in group B and C was less than that in group A. Conclusion: NGF is able to reduce threshold shift, promote recovery of auditory threshold and enzyme activity in acoustic trauma. This factor can, to some extent, protect noise induced hearing damage.