Yoneda Y, Ogita K, Azuma Y, Kuramoto N, Manabe T, Kitayama T
Department of Pharmacology, Setsunan University, Hirakata, Osaka, Japan.
Neuroscience. 1999;93(1):19-31. doi: 10.1016/s0306-4522(99)00117-7.
The systemic administration of N-methyl-D-aspartate (100 mg/kg, i.p.) resulted in preferential but transient expression of the transcription factor activator protein-1 in the granule cell layers of the dentate gyrus in the murine hippocampus by maximally 700% 1 h later, without markedly affecting that in the pyramidal cell layers of the CA1 and CA3 subfields for 4 h. The potentiation was completely prevented by prior administration of the N-methyl-D-aspartate channel blocker dizocilpine at 10 mglkg. By contrast, kainate (40 mg/kg, i.p.) potentiated activator protein-1 DNA binding in adjacent areas around the pyramidal and granule cell layers, in addition to potentiating that in neuronal cell layers of the CA1 and CA3 subfields and the dentate gyrus. Light microscopic analysis revealed that kainate, but not N-methyl-D-aspartate, induced marked losses of the pyramidal cells in the CAI and CA3 subfields, without affecting the dentate granule cells, for 14 days after administration. Limited proteolysis by V8 protease and supershift, as well as immunoblotting assays using antibodies against c-Fos and c-Jun, invariably gave support for differential expression by N-methyl-D-aspartate and kainate of the activator protein-1 complex consisting of different partner proteins. Moreover, two-dimensional electrophoresis followed by immunoblotting analysis revealed the expression of several nuclear proteins immunoreactive with the anti-c-Fos antibody at molecular weights and isoelectric points clearly different from those of c-Fos itself in response to kainate, but not N-methyl-D-aspartate, in the hippocampus. These results suggest that in vivo N-methyl-D-aspartate signals are predominantly transduced into cell nuclei to express activator protein-1 complex through molecular mechanisms different from those for kainate signals in the granule cells of the dentate gyrus in the murine hippocampus.
腹腔注射N-甲基-D-天冬氨酸（100毫克/千克）进行全身给药后，1小时后小鼠海马齿状回颗粒细胞层中转录因子激活蛋白-1出现优先但短暂的表达，最大增幅达700%，而在4小时内对CA1和CA3亚区锥体细胞层中的激活蛋白-1表达没有明显影响。预先给予10毫克/千克的N-甲基-D-天冬氨酸通道阻滞剂地佐环平可完全阻止这种增强作用。相比之下，腹腔注射红藻氨酸（40毫克/千克）除了增强CA1和CA3亚区以及齿状回神经元细胞层中的激活蛋白-1与DNA结合外，还增强了锥体细胞层和颗粒细胞层周围相邻区域的激活蛋白-1与DNA结合。光学显微镜分析显示，给药14天后，红藻氨酸而非N-甲基-D-天冬氨酸诱导CA1和CA3亚区的锥体细胞明显损失，而对齿状回颗粒细胞没有影响。V8蛋白酶有限的蛋白水解作用、超迁移以及使用抗c-Fos和c-Jun抗体的免疫印迹分析始终支持N-甲基-D-天冬氨酸和红藻氨酸对由不同伴侣蛋白组成的激活蛋白-1复合物的差异表达。此外，二维电泳后进行免疫印迹分析显示海马体中，在分子量和等电点上，有几种与抗c-Fos抗体发生免疫反应的核蛋白的表达，其与c-Fos本身明显不同，这是红藻氨酸而非N-甲基-D-天冬氨酸作用的结果。这些结果表明，在小鼠海马齿状回颗粒细胞中，体内N-甲基-D-天冬氨酸信号主要通过与红藻氨酸信号不同的分子机制转导至细胞核以表达激活蛋白-1复合物。
