谷氨酸受体2和钙离子在新生大鼠脑室周围白质软化症发病机制中的作用探讨

Roles of glutamate receptor 2 and cellular free calcium in the pathogenesis of periventricular leukomalacia

摘要:

目的：观察α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（α-3-hydroxy-5-methylisoxazole-4-propionie acid，AMPA）受体亚单位谷氨酸受体2（GluR2）在2日龄缺氧缺血新生鼠脑白质中的表达，并检测脑白质细胞内游离Ca2+浓度在缺氧缺血后不同时间点的变化及其意义。方法：建立2日龄SD大鼠缺氧缺血脑室周围白质软化(periventricular leukomalacia, PVL）模型，分别应用荧光定量PCR和Western Blot检测脑白质缺氧缺血后12，24，48 h和72 h GluR2 mRNA和蛋白表达的变化；用Furo 2/ AM荧光探针和双波长荧光分光光度计分别检测脑白质细胞内游离Ca2+浓度。结果：与对照组相比，PVL组大鼠脑白质GluR2 mRNA 和蛋白含量在缺氧缺血后24 h开始降低，并持续降低至72 h（P<0.05）； PVL组大鼠脑白质细胞内游离Ca2+浓度在缺氧缺血后12 h开始升高，持续增高至72 h（P<0.05）。结论：GluR2表达减少可能导致脑白质细胞内钙离子超载，引起细胞损害。［中国当代儿科杂志，2007，9（4）：313-316］

Abstract:

OBJECTIVE: To study the expression of the AMPA receptor subunit glutamate receptor 2 (GluR2) and the cellular free calcium concentration in the white matter of neonatal rats with periventricular leukomalacia (PVL) and their roles in the pathogenesis of PVL. METHODS: A PVL model was prepared by unilateral carotid artery ligation (UCL) followed by exposure to 6% oxygen for 4 hrs in 2-day-old rats. The neonatal rats performed a sham operation, without hypoxia-ischemia (HI), were used as the control group. At 12, 24, 48 and 72 hrs of HI, the expressions of GluR2 mRNA and protein in the white matter were detected using real time quantitative PCR and Western blot respectively. Spectrophotofluorimetry and Fura 2/AM were used to detect the cellular free calcium concentration. RESULTS: The expressions of GluR2 mRNA and protein in the white matter were significantly reduced in the PVL group at 24 hrs of HI, and remained at lower expressions until 72 hrs of HI compared with the control group (P<0.05). The cellular free calcium concentrations increased significantly in the PVL group at 12 hrs of HI, and remained at higher levels until 72 hrs of HI compared with the control group (P<0.05). CONCLUSIONS: The expressions of GluR2 mRNA and protein in the white matter decreased whereas the cellular free calcium concentration increased in neonatal rats with PVL. The decreased expression of GluR2 might lead to the overloading of cellular calcium in the white matter, which may cause neuronal damage and death.［Chin J Contemp Pediatr, 2007, 9 (4):313-316］