水杨酸钠对小鼠下丘核神经元γ-氨基丁酸和谷氨酸表达及听反应特性的影响

本研究探讨水杨酸钠对小鼠下丘核神经元γ-氨基丁酸（γ-aminobutyricacid,GABA）、谷氨酸（glutamate,Glu）表达及听反应的影响。36只成年健康昆明小鼠分为三组（每组12只）：对照组;NaSA组（水杨酸钠给药何天450mg／kg）;NaSA＋lidocaine组（水杨酸钠给药每天450mg/kg＋利多卡因给药每天10mg／kg）。各组均经腹腔注射给药,对照组给以同等剂量的生理盐水。给药15d后,免疫组织化学方法检测下丘核区神经元GABA、Glu的表达;细胞外电生理记录技术观察下丘核区神经元强度-发放率函数、强度-潜伏期函数和频率-调谐曲线的变化。结果如下：（1）NaSA组与NaSA＋lidocaine组GABA表达明显较对照组降低,但该两组比较无显著性差异;NaSA组Glu表达较对照组和NaSA＋lidocaine组明显增加,NaSA＋lidocaine组与对照组比较无显著性差异。（2）NaSA组强度-发放率函数呈低强度时上移,高强度时下降的非单调性改变;强度-潜伏期函数下移;调谐曲线从狭窄型向宽阔型转变。（3）NaSA＋lidocaine给药后强度-发放率函数无非单调性改变现象,强度-潜伏期函数下移的程度较NaSA组明显减轻,而神经元的调谐曲线从狭窄型向宽阔型转变例数也显著减少。以上结果提示：水杨酸钠能增强Glu阳性神经元表达,但抑制GABA阳性神经元表达;水杨酸钠可影响下丘核神经元的听反应特性,强度-发放率函数呈非单调性变化,强度-潜伏期函数下移,调谐曲线尖部变宽。利多忙因有逆转水杨酸钠改变下丘核神经元听反应的作用。

Effects of sodium salicylate on the expressions of gamma-aminobutyricacid and glutamate and auditory response properties of the inferior colliculus neurons

The effects of sodium salicylate (NaSA) on the expressions of gamma-aminobutyricacid (GABA) and glutamate (Glu), and auditory response properties of the inferior colliculus neurons in mice were studied. Thirty-six Kunming mice were divided into three groups: control group (saline injection); NaSA group (NaSA 450 mg/kg, i.p., each day for 15 d); NaSA + lidocaine group (NaSA 450 mg/kg + lidocaine 10 mg/kg, i.p., each day for 15 d). The expressions of GABA and Glu were examined with immunohistochemical method. The intensity-rate function, intensity-latency function and frequency-tuning curve were determined with extracellular electrophysiological recording. Results are as follows: (1) The expression of GABA in the NaSA and NaSA + lidocaine groups decreased remarkably compared with that in the control group; there was no noticeable difference between the NaSA and NaSA + lidocaine groups. The expression of Glu in the NaSA group increased significantly compared with that in the control and NaSA + lidocaine groups. No difference in the expression of Glu was found between the control and NaSA + lidocaine groups. (2) In NaSA group, the intensity-rate function displayed a non-monotonic pattern, rising at low intensity and descending at high intensity; the tip of frequency-tuning curves became broad after administration of NaSA. (3) The changes in intensity-rate function and intensity-latency function were not evident and the tips of the frequency-tuning curves sharpened in the NaSA + lidocaine group. These results suggest that administration of NaSA increases the expression of Glu-positive neurons and reduces that of GABA-positive neurons in the inferior colliculus. NaSA changes the auditory response properties of the inferior colliculus and lidocaine can reverse these changes.