一氧化氮合酶拮抗剂对豚鼠听觉核团诱发电位及CAP的影响

Effects of NOS antagonist on cochlear complex action potential and evoked potential in auditory nuclei of guinea pig

目的：探讨听觉核团一氧化氮（ＮＯ）的可能作用．方法：用核团内微量药物注射及听觉电生理方法，研究一氧化氮合酶拮抗剂Ｎ－甲基－Ｌ－精氨酸（ＮＭＬＡ）对豚鼠核团内听觉诱发电位（ＡＥＰ）、耳蜗复合动作电位（ＣＡＰ）的影响．结果：听觉中枢各核团内分别注入ＮＭＬＡ后，核团内听觉诱发电位均明显增大．短声诱发的耳蜗核内ＡＥＰ（ＣＮ－ＡＥＰ）为（９８．６９±３．２８）μＶ，下丘内ＡＥＰ（ＩＣ－ＡＥＰ）为（１３６．３９±３．２４）μＶ，内侧膝状体内ＡＥＰ（ＭＧＢ－ＡＥＰ）为（１７２．４８±３．９６）μＶ，与注射ＮＭＬＡ前相差显著（Ｐ＜０．０５）．短纯音诱发的ＣＮ－ＡＥＰ以２５０Ｈｚ～１ｋＨｚ变化显著（Ｐ＜０．０１），其中５００Ｈｚ是正常对照的２．０１倍（Ｐ＜０．０１），ＩＣ－ＡＥＰ以２～４ｋＨｚ变化显著（Ｐ＜０．０５），ＭＧＢ－ＡＥＰ以４～６ｋＨｚ变化显著（Ｐ＜０．０５）．ＣＡＰＮ１波振幅降低，尤以ＣＮ内注射ＮＭＬＡ最为显著（Ｐ＜０．０１）．核团内ＡＥＰ潜伏期缩短．结论：听觉核团内的ＮＯ对听觉感受神经元的兴奋性及同步化有调节作用．可能直接或通过上橄榄复合体改变耳蜗神经的敏感性．

Objective: To investigate the roles of NO in auditory nuclei. Methods: Infusion of micromedicine into nuclei and auditory eletrophysiological method were adopted to study the effects of N methy Lmonoarginine (NMLA), NOS antagonist, on auditory evoked potential (AEP) in auditory nuclei and complex action potential (CAP) in cochlear of guinea pig. Results: AEP in every auditory nucleus increased after injection of NMLA. AEP in cochlear nucleus (CN AEP) induced by Click was (98.69±3.28) μV; in inferior colliculus (IC), (136.39±3.28) μV; in medial geniculate body (MGB), (172.48±3.96) μV, which was significantly different from before injection of NMLA ( P <0.05). Change of CN AEP induced by Tone brust was obvious between 250 Hz～1 kHz( P <0.01), and at 500 Hz, CN AEP was 2.01 times as normal ( P <0.01); IC AEP, 2～4 kHz ( P <0.05); and MGB AEP, 4～6 kHz ( P <0.05). Amplitude of vibration of CAP N1 decreased especially after infusing NMLA into CN ( P <0.01). AEP latent periods in nuclei were shortened. Conclusion: It is suggested that NO might control the excitability and synchronization of auditory sensory neuron in auditory nuclei, and might change the sensibility of cochlear neuron directly or through superior olivary complex.