次声脑损伤后脑组织谷氨酸转运蛋白1的改变及其意义

Change of excitatory amino acid transporter 1 in brain tissues after infrasonic damage and its significance

目的:探讨8Hz130dB次声作用后脑组织中谷氨酸转运蛋白1的表达改变及其意义。方法:实验于2005/10在解放军第四军医大学西京医院神经外科实验室完成。选择解放军第四军医大学实验动物中心提供的成年雄性清洁级SD大鼠40只,随机数字表法分为正常对照组、次声作用1,7及14d共4组,每组10只。次声作用1,7及14d组按1次/d在次声压力仓内作用2h,分别作用1,7和14d。实验用8Hz130dB的次声。对照组按1次/d在次声压力仓内滞留2h而无次声作用。采用westernblot法行蛋白测定,RT-PCR法行mRNA测定。β-肌动蛋白在细胞内含量稳定,故选用β-肌动蛋白作为内参照。观察各次声作用组及对照组大鼠谷氨酸转运蛋白1及mRNA梯度灰度值。结果:在实验过程中,无动物死亡,全部进入结果分析。①与对照组谷氨酸转运蛋白1灰度值186±4.2相比,次声作用1d组8Hz130dB次声作用后,大鼠谷氨酸转运蛋白1发生下调,为172±3.8,连续作用7d后明显下调至169±4.9,次声作用14d后谷氨酸转运蛋白1下调非常明显,为167±3.9。②与对照组谷氨酸转运蛋白1mRNA灰度值140±4.9相比,次声作用1d组8Hz130dB次声作用后谷氨酸转运蛋白1mRNA即发生下调,为131±3.7,连续7d照射后明显下调至128±5.1,连续14d照射后谷氨酸转运蛋白1mRNA下调非常明显,为121±3.9。③次声作用1d组大鼠出现大便增多、变稀,较为躁动;次声作用7d组躁动更明显;14d组大鼠的躁动非常明显,有的出现反应性下降。结论:在次声脑损伤后,谷氨酸在细胞外堆积,可能与谷氨酸转运蛋白1下调导致谷氨酸重吸收障碍有关。上调谷氨酸转运蛋白1可能对次声脑损伤后脑组织有保护作用。

AIM： To investigate the changes and significance of the excitatory amino acid transporter 1 （EAAT1） in brain tissues after 8 Hz 130 dB infrasonic damage. METHODS： The experiment was conducted at the Laboratory of Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University of Ghinese PLA in October 2005. Totally 40 clean adult SD male rats were selected from Experimental Animal Center, Fourth Military Medical University and they were randomly divided into four groups： normal control group and 1-time, 7-time, 14-time infrasonic damage groups with 10 rats in each group. The rats in the 1-time, 7-time, 14-time infrasonic damage groups were exposed to 8Hz 130 dB infrasound for two hours each day for 1 day, 7 days and 14 days, respectively. The rats of control group were put into the infrasonic apparatus that had no infrasound for two hours each day. Western-blot was adopted to detect the changes of protein and the mRNA was detected with RT-PCR. Content of β-actin in cells was stable, so β-actin was used as internal reference. Gray levels of EAAT1 and mRNA in rats were observed in each infrasonic damage group and control group. RESULTS： All the animals were involved in the result analysis, no drop-out. ①EAAT1 had tendency of down-regulation （172±3.8） after 8 Hz 130 dB infrasonic damage in 1-time infrasonic damage groups compared with that in the control group （186±4.2）, In 7-time infrasonic damage group it was down-regulation obviously （169±4.9）. In the 14-time group the EAAT1 down regulation was more severe （167±3.9）. ②Compared with the gray level of EAAT1 mRNA in the control group （140±4.9）, the level of EAAT1 mRNA in the 1-time infrasonic damage group was down-regulation after 8 Hz 130 dB infrasound effect （131±3,7）. After irradiation for 7 days continuously, the level was down-regulation by （128±5.1）. After irradiation for 14 days continuously, the level of EAAT1 mRNA was significantly down-regulation by （121±3.9）. ③Rats in the 1-time infrasonic damage group had more sedes that became loose; The rats also became restlessness. The restlessness was more significant in the 7-time infrasonic damage group; It was very significant in the 14-time group, some with decreased reactivity. CONCLUSION： Glutamate cumulate in ectocytic accumulation may be concerned with malabsorption due to EAAT1 down-regulation after infrasonic brain damages. The up-regulation of EAAT1 maybe has protective effect on the brain tissues after infrasonic damage.