碱性成纤维细胞生长因子对新生大鼠缺血脑组织转化生长因子β1及其受体mRNA表达的影响

目的 研究碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)对3日龄新生大鼠脑缺血后星形胶质细胞数目以及转化生长因子-β1(transforming growth factor-β1,TGF-β1)及其受体--Smad2mRNA表达的影响,探讨bFGF对未成熟脑缺血性损伤的保护作用机制. 方法 结扎3日龄新生SD大鼠双侧颈总动脉制备脑缺血模型,随机分为对照组(33只)、治疗组(33只).另取3日龄新生SD大鼠33只为假手术组.免疫荧光染色方法检测三组大鼠术后4 d、7 d和14 d脑室下区胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)阳性细胞数目;实时荧光定量PCR(real-time PCR)技术检测三组大鼠术后4 d、7 d和14 d脑室下区TGF-β1及Srnad2 mRNA表达变化. 结果 (1)假手术组GFAP阳性细胞术后7 d达高峰(325.4±52.5)个/视野],对照组、治疗组GFAP阳性细胞数术后14 d达高峰分别为(533.5±75.7)、(727.2±104.5)个/视野)],三组同时点比较差异有统计学意义(P＜0.01).(2)对照组TGF-β1和Smad2 mRNA表达在术后7 d达高峰(分别为7.67±1.22和6.22±1.92),治疗组TGF-β1和Smad2 mRNA表达在术后14 d达高峰(分别为8.65±1.02和7.67±1.41),三组同时点比较差异有统计学意义(P＜0.01). 结论 未成熟脑缺血后,外源性bFGF可通过诱导TGF-β1的表达,引起星形胶质细胞反应性增生,而发挥其神经营养作用.

Effects of basic fibroblast growth factor on mRNA expression of transforming growth factor-β1 and its receptor in neonatal rats after brain ischemia

Objective To address the neuroprotective mechanism of basic fibroblast growth factor(bFGF)on ischemic brain injury in neonatal rats.Methods Sixty-six brain ischemia models of 3-day-old Sprague-Dawley rats were made by occluding bilateral common carotid artery.The models were randomly divided into two groups:trial group and control group with 33 rats in each group.The rats of trial group were administrated bFGF 5μg/d through intraperitoneal injection,3 days consecutively.The other thirty-three rats were taken into the sham operation group.The number of gtial fibrillary acidic protein(GFAP)positive cells in the subventricular zone of rata'brain was observed with immunofluorescence assays at the 4th,7th and 14th days after the operation.The mRNA expression of transforming growth factor-β1(TGF-β1)and its receptor Smad2 in the subventricular zone were examined by real-time PCR assays at the above mentioned time points respectively.Results (1)The number of GFAP positive cells in the subventricular zone of the sham operation group was highest at the 7th day(325.4±52.5),and it reached peak at the 14th day in the control group(533.5±75.7)and the trial group(727.2±104.5),there was a significant difference in three groups at each time point(P＜0.01).(2)TGF-β1 and Smad2 mRNA expression peaked at the 7th dayin control group(7.67±1.22,6.22±1.92,respectively),and it reached peak at the 14th day in the trial group(8.65±1.02,7.67±1.41,respectively),there was a significant difference in three groups at each time point(P＜0.01).Conchtsions Exogenous bFlGF could increase the number of astrocytes by inducing the expression of TGF-81 in the subventricular zone of neonatal rats after brain ischemia.