Lehman M N, LeSauter J, Kim C, Berriman S J, Tresco P A, Silver R
Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, OH 45267, USA.
Cell Transplant. 1995 Jan-Feb;4(1):75-81. doi: 10.1177/096368979500400111.
Fetal grafts containing the hypothalamic suprachiasmatic nucleus (SCN), the site of an endogenous circadian pacemaker, can reinstate behavioral rhythms in lesioned recipients but the precise routes of communication between the graft and the host brain remain unknown. Grafts containing the SCN may convey temporal information to the host brain via neural efferents, diffusible factors, or a combination of both. We examined graft-host connections in anterior hypothalamic homografts (hamster-to hamster) and heterografts (rat-to hamster) implanted in the third ventricle by: (a) applying the carbocyanine dye, diI, directly onto homo- and heterografts in fixed tissue sections; and (b) using a donor-specific neurofilament (NF) antibody to immunocytochemically visualize heterograft efferents. DiI applied onto either homografts or heterografts labeled relatively few graft efferents which could be followed only short distances into the host brain. In contrast, NF-labeled heterograft efferents were both more numerous and extended for longer distances into the host brain than anticipated on the basis of diI tract tracing. The results suggest that anterior hypothalamic grafts implanted in the third ventricle provide substantial input to the adjacent host hypothalamus although it is not known whether these projections arise from SCN cells or from other extra-SCN hypothalamic tissue within these grafts. Nor is it known whether these projections are functional. To determine if neural efferents are required for the restoration of rhythmicity after grafting, we have encapsulated fetal anterior hypothalamus in a permselective polymer which prevents neurite outgrowth but allows diffusible signals to reach the host brain.(ABSTRACT TRUNCATED AT 250 WORDS)
含有下丘脑视交叉上核（SCN）（内源性昼夜节律起搏器所在部位）的胎儿移植物能够使受损受体恢复行为节律，但移植物与宿主脑之间的确切通信途径仍不清楚。含有SCN的移植物可能通过神经传出纤维、可扩散因子或两者的组合将时间信息传递给宿主脑。我们通过以下方法研究了植入第三脑室的前下丘脑同基因移植物（仓鼠对仓鼠）和异基因移植物（大鼠对仓鼠）中的移植物 - 宿主连接：（a）将羰花青染料DiI直接应用于固定组织切片中的同基因和异基因移植物上；（b）使用供体特异性神经丝（NF）抗体通过免疫细胞化学方法可视化异基因移植物的传出纤维。将DiI应用于同基因或异基因移植物上时，标记的移植物传出纤维相对较少，且只能追踪到宿主脑内较短的距离。相比之下，基于DiI束追踪预期，NF标记的异基因移植物传出纤维数量更多，并且向宿主脑内延伸的距离更长。结果表明，植入第三脑室的前下丘脑移植物为相邻的宿主下丘脑提供了大量输入，尽管尚不清楚这些投射是来自SCN细胞还是这些移植物中SCN以外的其他下丘脑组织。也不清楚这些投射是否具有功能。为了确定移植后恢复节律性是否需要神经传出纤维，我们将胎儿前下丘脑包裹在一种选择性通透聚合物中，该聚合物可防止神经突生长，但允许可扩散信号到达宿主脑。（摘要截断于250字）
