牛磺酸对大鼠视网膜谷氨酸兴奋毒性的防护作用研究

目的:探明牛磺酸能否有效防护谷氨酸兴奋毒性引起的大鼠视网膜尤其是视网膜神经节细胞(retinalganglioncells,RGCs)损伤。方法:通过玻璃体注射谷氨酸建立大鼠视网膜谷氨酸兴奋毒性损伤模型,分为正常对照组,谷氨酸组,牛磺酸干预高、低剂量组,MK-801干预组(阳性对照组)和玻璃体注射PBS对照组。观察谷氨酸兴奋毒性对大鼠视网膜组织病理结构、超微结构、视网膜电图、RGCs数量的影响及牛磺酸的防护效应。结果:玻璃体注射谷氨酸使视网膜内层尤其是内网状层厚度变薄;内核层细胞:RGCs的超微结构发生变性改变;视网膜电图的a波、b波下降;神经节细胞层的细胞数显著减少(减少53%),以RGCs的减少为主(减少75%)。腹腔注射高剂量(25mg/kgbw)牛磺酸可有效防护谷氨酸所致上述损伤及RGCs数量的减少,而低剂量(5mg/kgbw)牛磺酸的作用不明显。结论:牛磺酸可有效防护谷氨酸兴奋毒性引起的视网膜尤其是RGCs损伤。

THE PROTECTIVE EFFECTS OF TAURINE AGAINST GLUTAMATE-INDUCED EXCITOTOXICITY IN RAT RETINA

Objective: The purpose of this study was to determine whether taurine had retinal neuroprotective effects against glutamate-induced excitototxicity, especially in retinal ganglion cells (RGCs) damage in adult rat. Methods: We used a rat model of retinal glutamate excitotoxicity induced by intravitreal injection of 40 nmol glutamate in one eye. The retinal damage was evaluated by counting the number of cells in the ganglion cell layer (GCL) in flat mount preparations of whole retinas, examining the a- and b-waves in the electroretinogram (ERG), hematoxylin-eosin (HE) staining, and observing ultrastructure of retinas. Results: After intravitreal injection of glutamate, thinning of inner retinal layers, smaller a- and b-waves in the ERG were observed, and degenerative changes were observed in inner nuclear layer and RGCs by electron microscopy. These damages could be prevented by 25mg/kg bw taurine (intraperitoneal injection). 5mg/kg taurine had unremarkable effect. In animals that received intravitreal injection of glutamate, there was significant reduction (53%) in total cell numbers in GCL, with 75% reduction in RGCs. 25mg/kg bw taurine-treated animals showed a significant reduction in glutamate- induced RGCs loss. Conclusion:Repeated application of taurine can prevent glutamate-induced retinal neuronal cell damage, especially in RGCs and retinal functional damage in rats.