红藻氨酸诱导癫痫发作大鼠脑内GLAST表达的动态研究

摘要

Objective:To observe expression of glutamate transporter GLAST in rat brains following KA induced seizure activity.Methods:GLAST expression in rat brains following KA injection was studied by immunocytochemistry staining with guinea pig anti-glutamate transporter GLAST polyclonal antibody. Results:GLAST-immunoreactive cells were found in both neurons and astroglia. After KA treatment,a rapid increase of GLAST-positive immunoreactive cells in cerebellum was observed which began at 30 min post-injection, reached a peak at 3 h and then a decrease trend was followed. The GLAST immunoreactivity in cerebellum was lower than that of controls by 12 h and returned to normal level by 72 h after KA injection. The GLAST-positive astrocytes in hippocampus region had a similar increase within 3～6 h following KA treatment and this change was prominent in CA3 .Conclusion:GLAST expression in rat brains following KA-induced seizure activity had a rapid and transient upregulation which may be a protective response of cells to injury, and this change would allow the scavenging of excess extracelluar glutamate and prevention of excitotoxicity. It could also have a significant role in controlling levels of excitability in limbic circuitry.%目的：观察红藻氨酸（kainic acid ,KA）诱导大鼠癫痫发作时脑内谷氨酸转运蛋白亚型GLAST表达的变化。方法：用豚鼠抗GLAST多克隆抗体及免疫细胞化学ABC法观察KA注射后不同时间脑内GLAST的表达。结果：KA注射后1 h,小脑分子层和蒲肯野氏细胞层的GLAST免疫反应强度开始增加，至3 h达高峰（P＜0.01）,随后呈下降趋势，12 h时低于发作前水平（P＜0.05）,72 h恢复正常。海马区表达的GLAST阳性星形胶质细胞于KA注射后3～6 h内亦有相应的升高，以CA3区改变最明显（P＜0.05）。结论：KA诱导大鼠癫痫发作时脑内GLAST的表达早期呈现快速上调，其机理可能是细胞对损伤的一种保护性反应，有助于清除细胞外过量的谷氨酸，预防其对神经元的兴奋性毒性作用，并对控制边缘环路的兴奋性有重要作用。