Munekawa K, Tamada Y, Iijima N, Hayashi S, Ishihara A, Inoue K, Tanaka M, Ibata Y
Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, 602-0841, Japan.
Exp Neurol. 2000 Nov;166(1):44-51. doi: 10.1006/exnr.2000.7490.
The development of astroglial cells and the effect of the retinohypothalamic tract on it were studied by vimentin and glial fibrillary acidic protein (GFAP) immunocytochemistry in the suprachiasmatic nucleus (SCN) of the rat. At the embryonic stage, vimentin-immunoreactive (VIM-IR) radial glia, precursors of astrocytes, were dominant. However, their filaments vanished in the first few postnatal days. Instead of VIM-IR glial filaments, GFAP-immunoreactive (GFAP-IR) astrocytes appeared at E20 and grew rapidly from the P3 stage. GFAP immunoreactivity in the ventrolateral portion of the SCN (VLSCN) was measured using a computer-assisted image analyzing system. In normal rats, GFAP immunoreactivity showed a stepwise pattern with two slopes at P3-P4 and P20-P25. Bilaterally eye-enucleated rats operated on the day of birth showed lower GFAP immunoreactivity than normal rats and the GFAP immunoreactivity did not increase between P20 and P25 when GFAP-IR glial processes rapidly expand. Electron microscopic investigation at P50 (adult stage) revealed that neurons in the VLSCN had often direct apposition without astroglial processes and the frequency of this finding was significantly higher in eye-enucleated rats than in the control rats. These findings strongly suggest that the postnatal development of astroglial elements, particularly the expansion of GFAP-IR processes in the SCN, is regulated by retinohypothalamic projection.
通过波形蛋白和胶质纤维酸性蛋白（GFAP）免疫细胞化学方法，在大鼠视交叉上核（SCN）中研究了星形胶质细胞的发育以及视网膜下丘脑束对其的影响。在胚胎期，波形蛋白免疫反应阳性（VIM-IR）的放射状胶质细胞，即星形胶质细胞的前体，占主导地位。然而，它们的细丝在出生后的头几天消失了。在E20时，出现了GFAP免疫反应阳性（GFAP-IR）的星形胶质细胞，取代了VIM-IR胶质细丝，并从P3阶段开始迅速生长。使用计算机辅助图像分析系统测量SCN腹外侧部分（VLSCN）中的GFAP免疫反应性。在正常大鼠中，GFAP免疫反应性在P3-P4和P20-P25呈现出有两个斜率的阶梯式模式。出生当天进行双侧眼球摘除手术的大鼠，其GFAP免疫反应性低于正常大鼠，并且在P20和P25之间，当GFAP-IR胶质突起迅速扩展时，GFAP免疫反应性并未增加。在P50（成年期）进行的电子显微镜研究显示，VLSCN中的神经元常常直接相邻，没有星形胶质突起，并且在眼球摘除大鼠中这一发现的频率显著高于对照大鼠。这些发现有力地表明，星形胶质细胞成分的出生后发育，特别是SCN中GFAP-IR突起的扩展，受视网膜下丘脑投射的调节。
