Botchkina G I, Morin L P
Department of Psychiatry, Stony Brook University, NY 11794, USA.
Brain Res Dev Brain Res. 1995 May 26;86(1-2):48-56. doi: 10.1016/0165-3806(95)00017-8.
Circadian rhythmicity of rodents is a property of the suprachiasmatic nucleus (SCN). Such rhythmicity can be demonstrated in the prenatal SCN, yet there is little information about the cells in which rhythmicity is generated. The present study was performed to discover the developmental relationships of SCN glial cells and a class of identifiable SCN neurons. Toward this end, vimentin- (VIM), glial fibrillary acidic protein- (GFAP) and vasoactive intestinal peptide- (VIP) immunoreactivity were investigated in SCN radial glia, astrocytes and neurons, respectively. VIP-IR first appears at embryonic day 13 (E13) and is clearly identifiable in neurons at E14. Substantial axon extension begins at E15 and the postnatal day 10 (P10) SCN is adult-like. VIM-IR radial glia fill the SCN region at E13, but by P0, most are absent. On P3, the remaining processes are beaded suggesting degeneration. The first GFAP-IR elements are visible on E15 with a few clear astrocytes present at P0. The number of astrocytes lateral to and in the SCN continues to increase during the postnatal period achieving an adult-like appearance by P21. The data do not support the view that prenatal circadian rhythmicity is derived from astrocytes. VIP-IR neurons are apparently present sufficiently early to be part of the rhythm generating mechanism. These tissues are discussed in the context of development of the SCN.
啮齿动物的昼夜节律性是视交叉上核（SCN）的一种特性。这种节律性在产前的SCN中即可表现出来，然而关于产生节律性的细胞却知之甚少。本研究旨在探索SCN神经胶质细胞与一类可识别的SCN神经元之间的发育关系。为此，分别对视交叉上核的放射状胶质细胞、星形胶质细胞和神经元中的波形蛋白（VIM）、胶质纤维酸性蛋白（GFAP）和血管活性肠肽（VIP）免疫反应性进行了研究。VIP免疫反应性首先出现在胚胎第13天（E13），并在E14时在神经元中清晰可辨。大量轴突延伸始于E15，出生后第10天（P10）的SCN已类似成年状态。波形蛋白免疫反应性放射状胶质细胞在E13时充满SCN区域，但到出生时（P0），大部分已消失。在P3时，剩余的突起呈串珠状，提示退变。最早的GFAP免疫反应性成分在E15时可见，P0时有一些清晰的星形胶质细胞。视交叉上核内外侧的星形胶质细胞数量在出生后持续增加，到P21时呈现类似成年的外观。数据不支持产前昼夜节律性源自星形胶质细胞的观点。VIP免疫反应性神经元显然出现得足够早，可成为节律产生机制的一部分。本文结合视交叉上核的发育情况对这些组织进行了讨论。
