[利用大鼠动物行为模型评估某些药物对耳鸣的影响]

Wang H, Jiang S, Yang W, Han D

Institute of Otorhinolaryngology, Chinese PLA General Hospital, Beijing 100853, China.

Zhonghua Er Bi Yan Hou Ke Za Zhi. 2000 Oct;35(5):331-4.

OBJECTIVE

To develop a valid behavioral animal model of tinnitus and to determine the animals whether have the perception of tinnitus and to evaluate effects of nimodipine and Chinese herbs on tinnitus using the behavioral model.

METHODS

Adult male albino rats (n = 60) were fell evenly and randomly into ten groups. Animals in Group I and II were administrated sodium salicylate 350 mg/kg/d (i.p.). Instead, animals in control groups (Group III and IV) were saline injected. Pure tone (8 kHz, 65 dBSPL) was given to rats in Group V and VI instead of sodium salicylate. Nimodipine (1 mg/kg) were administrated to animals in Group VII and VIII. Gushenshuerfang, one kind of Chinese herbs were administrated to animals in Group IX and X. Medicine or pure tone were being given to all animals in Group I, III, V, VII, IX before conditioned reflex. Animals in Group II, IV, VI, VIII, X began to have medicine or pure tone after conditioned reflex. Thirsty animals (deprived of water for several days) were breeded in sound-proofed room and listened a persistent white noise (55 dB SPL) and trained daily with our instrument system, according to the procedure based on Pavlovian conditioned suppression paradigm. Subjects were permitted to lick water at an automatic dispenser during daily training sessions and the number of licks was recorded automatically. Noise offset (silence) was the conditioned stimulus and the electrical shock was the unconditioned stimulus. After two or three days training, subjects learnt rapidly to associate noise offset with shock and then established a behavioral conditioned reflex. Because of shock fear they decrease or even stop licking with the presentations of conditioned stimulus. However, subjects gradually forgot or ignored the fear without any shock present in extinction test sessions.

RESULTS

Animals' licking recovered to their pre-training levels respectively at the following days: Group I--5 days, Group II--2 days, both Group III and IV--4 days, Group V--5 days, Group VI--2 days, Group VII--5 days, Group VIII--4 days, Group IX--5 days, Group X--4 days. There were much significant differences among all groups and all training days (F test, P < 0.001). Above results provided sufficient evidence for that tinnitus was induced by salicylate and tinnitus presented with noise offset. In group I, tinnitus became additional conditioned stimulus. Therefore, the fear of animals was much severe and the numbers of licking were much fewer. Extinction lasted longer. In group II, animals ignored the noise offset much easily and the extinction lasted much shorter. Moreover, results from group V and VI, pure tone instead of salicylate, indicated that sensation (tinnitus) sounded like pure tone. The groups VII, VIII, IX, X demonstrated that nimodipine and Gushenshuerfang, one kind of Chinese herbs can cure the tinnitus induced by salicylate.

CONCLUSION

All behavioral evidence indicated that animals perceived tinnitus induced by salicylate and this animal model could be used in evaluating curative effects of some medicine on tinnitus.

目的

建立一种有效的耳鸣行为动物模型，确定动物是否有耳鸣感知，并使用该行为模型评估尼莫地平和中药对耳鸣的影响。

方法

将60只成年雄性白化大鼠均匀随机分为10组。第一组和第二组动物腹腔注射水杨酸钠350mg/kg/d。相反，对照组（第三组和第四组）动物注射生理盐水。第五组和第六组大鼠给予纯音（8kHz，65dBSPL）而非水杨酸钠。第七组和第八组动物给予尼莫地平（1mg/kg）。第九组和第十组动物给予一种中药——固肾双耳方。第一组、第三组、第五组、第七组、第九组的所有动物在条件反射前给予药物或纯音。第二组、第四组、第六组、第八组、第十组的动物在条件反射后开始给予药物或纯音。将口渴的动物（禁食禁水数天）饲养在隔音室内，让其听持续的白噪声（55dB SPL），并根据基于巴甫洛夫条件性抑制范式的程序，每天用我们的仪器系统进行训练。在每日训练期间，允许实验对象在自动饮水器处舔水，并自动记录舔水次数。噪声抵消（静音）为条件刺激，电击为非条件刺激。经过两三天的训练，实验对象迅速学会将噪声抵消与电击联系起来，然后建立行为条件反射。由于电击恐惧，它们在条件刺激出现时会减少甚至停止舔水。然而，在消退测试期间，实验对象在没有任何电击的情况下逐渐忘记或忽略了恐惧。

结果

在接下来的几天里，各组动物的舔水次数分别恢复到训练前水平：第一组——5天，第二组——2天，第三组和第四组——4天，第五组——5天，第六组——2天，第七组——5天，第八组——4天，第九组——5天，第十组——4天。所有组和所有训练天数之间存在显著差异（F检验，P<0.001）。上述结果为水杨酸盐诱导耳鸣且耳鸣与噪声抵消有关提供了充分证据。在第一组中，耳鸣成为额外的条件刺激。因此，动物的恐惧更严重，舔水次数更少。消退持续时间更长。在第二组中，动物更容易忽略噪声抵消，消退持续时间更短。此外，第五组和第六组用纯音代替水杨酸盐的结果表明，感觉（耳鸣）听起来像纯音。第七组、第八组、第九组、第十组表明，尼莫地平和一种中药固肾双耳方可治愈水杨酸盐诱导的耳鸣。