Tanaka Hidenobu, Katoh Akira, Oguro Keiji, Shimazaki Kuniko, Gomi Hiroshi, Itohara Shigeyoshi, Masuzawa Toshio, Kawai Nobufumi
Department of Surgical Neurology, Jichi Medical School, Tochigi, Japan.
J Neurosci Res. 2002 Jan 1;67(1):11-20. doi: 10.1002/jnr.10004.
GFAP (glial fibrillary acidic protein) is an intermediate filament protein found exclusively in the astrocytes of the central nervous system. We studied the role of GFAP in the neuronal degeneration in the hippocampus after transient ischemia using knockout mice. Wild-type C57 Black/6 (GFAP(+/+)) mice and mutant (GFAP(-/-)) mice were subjected to occlusion of both carotid arteries for 5-15 min. Hippocampal slices were prepared 3 days after reperfusion and the field excitatory postsynaptic potentials (fEPSP) in the CA1 were recorded. High frequency stimulation induced robust long-term potentiation (LTP) in GFAP(-/-), as in GFAP(+/+) mice. After ischemia, however, the LTP in GFAP(-/-) was significantly depressed. Similarly, paired pulse facilitation (PPF) displayed little difference between GFAP(+/+) and GFAP(-/-), but after ischemia, the PPF in GFAP(-/-) showed a depression. Histological study revealed that loss of CA1 and CA3 pyramidal neurons after ischemia was marked in GFAP(-/-). MAP2 (dendritic) immunostaining in the post-ischemic hippocampus showed little difference but NF200 (axonal) immunoreactivity was reduced in GFAP(-/-). S100beta (glial) immunoreactivity was similar in the post-ischemic hippocampus of the GFAP(+/+) and GFAP(-/-), indicating that reactive astrocytosis did not require GFAP. Our results suggest that GFAP has an important role in astrocyte-neural interactions and that ischemic insult impairs LTP and accelerates neuronal death.
胶质纤维酸性蛋白（GFAP）是一种仅在中枢神经系统星形胶质细胞中发现的中间丝蛋白。我们使用基因敲除小鼠研究了GFAP在短暂性脑缺血后海马神经元变性中的作用。将野生型C57黑/6（GFAP(+/+)）小鼠和突变型（GFAP(-/-)）小鼠的双侧颈动脉闭塞5 - 15分钟。再灌注3天后制备海马切片，并记录CA1区的场兴奋性突触后电位（fEPSP）。与GFAP(+/+)小鼠一样，高频刺激在GFAP(-/-)小鼠中诱导出强烈的长时程增强（LTP）。然而，缺血后，GFAP(-/-)小鼠中的LTP显著降低。同样，配对脉冲易化（PPF）在GFAP(+/+)和GFAP(-/-)之间显示出微小差异，但缺血后，GFAP(-/-)小鼠中的PPF出现降低。组织学研究显示，GFAP(-/-)小鼠缺血后CA1和CA3锥体神经元的丢失明显。缺血后海马中微管相关蛋白2（MAP2，树突）免疫染色显示差异不大，但神经丝蛋白200（NF200，轴突）免疫反应性在GFAP(-/-)小鼠中降低。S100β（胶质细胞）免疫反应性在GFAP(+/+)和GFAP(-/-)小鼠缺血后的海马中相似，表明反应性星形胶质细胞增生不需要GFAP。我们的结果表明，GFAP在星形胶质细胞与神经元的相互作用中起重要作用，并且缺血性损伤会损害LTP并加速神经元死亡。
