Luo J, Lang J A, Miller M W
Department of Psychiatry, University of Iowa College of Medicine, Iowa City 52242-1000, USA.
J Neurochem. 1998 Aug;71(2):526-34. doi: 10.1046/j.1471-4159.1998.71020526.x.
The hypothesis that transforming growth factor beta1 (TGFbeta1) regulates the synthesis of prostaglandins by CNS tissue was tested by using purified cultures of cortical astrocytes or neurons that were obtained from rat pups on postnatal day 4 or 5 or fetuses on gestational day 16, respectively. The cells were exposed to TGFbeta1 for 2 days. The synthesis of prostaglandins depends upon the production and conversion of arachidonic acid, steps that are catalyzed by phospholipase A2 (PLA2) and cyclooxygenase (COX), respectively. Prostaglandin E2 (PGE2) concentration was determined by radioimmunoassay. The expression of cytosolic PLA2 and COX (the constitutive COX1 and the inducible COX2) was assessed by using immunohistochemical and quantitative immunoblotting procedures. Astrocytes produced much more PGE2 than neurons, suggesting that glial cells are an important source of PGE2 in the CNS. TGFbeta1 increased the production of PGE2 by astrocytes and neurons in a concentration-dependent manner. Furthermore, TGFbeta1 enhanced COX activity; the inhibitor indomethacin completely blocked TGFbeta1-mediated PGE2 synthesis. Cultured astrocytes and neurons expressed the three enzymes: cytosolic PLA2, COX1, and COX2. Cytosolic PLA2 expression was unaffected by TGFbeta1 treatment. In contrast, COX expression was altered by TGFbeta1 treatment in a concentration-dependent fashion. COX1 was increased by TGFbeta1, but only in astrocytes. TGFbeta1 increased COX2 expression in astrocytes and neurons. Thus, TGFbeta1-induced increases in PGE2 concentration are regulated by COX. This study suggests that TGFbeta1 is an important regulator of immune and inflammatory processes in the CNS.
通过分别使用从出生后第4天或第5天的大鼠幼崽或妊娠第16天的胎儿获得的皮质星形胶质细胞或神经元的纯化培养物，来检验转化生长因子β1（TGFβ1）调节中枢神经系统组织中前列腺素合成的假说。将细胞暴露于TGFβ1 2天。前列腺素的合成取决于花生四烯酸的产生和转化，这两个步骤分别由磷脂酶A2（PLA2）和环氧化酶（COX）催化。通过放射免疫测定法测定前列腺素E2（PGE2）的浓度。使用免疫组织化学和定量免疫印迹程序评估胞质PLA2和COX（组成型COX1和诱导型COX2）的表达。星形胶质细胞产生的PGE2比神经元多得多，这表明神经胶质细胞是中枢神经系统中PGE2的重要来源。TGFβ1以浓度依赖的方式增加星形胶质细胞和神经元中PGE2的产生。此外，TGFβ1增强了COX活性；抑制剂吲哚美辛完全阻断了TGFβ1介导的PGE2合成。培养的星形胶质细胞和神经元表达三种酶：胞质PLA2、COX1和COX2。TGFβ1处理对胞质PLA2的表达没有影响。相反，TGFβ1处理以浓度依赖的方式改变COX的表达。TGFβ1增加了COX1的表达，但仅在星形胶质细胞中。TGFβ1增加了星形胶质细胞和神经元中COX2的表达。因此，TGFβ1诱导的PGE2浓度增加是由COX调节的。这项研究表明，TGFβ1是中枢神经系统免疫和炎症过程的重要调节因子。
