Thalamus is an important sensory relay station: afferent sensory information, except olfactory signals, is transmitted by thalamocortical axons (TCAs) to the cerebral cortex. The pathway choice of TCAs depends on diverse diffusible or substrate-bound guidance cues in the environment. Not only classical guidance cues (ephrins, slits, semaphorins, and netrins), morphogens, which exerts patterning effects during early embryonic development, can also help axons navigate to their targets at later development stages. Here, expression analyses reveal that morphogen Fibroblast growth factor (FGF)-3 is expressed in the chick ventral diencephalon, hypothalamus, during the pathfinding of TCAs. Then, using in vitro analyses in chick explants, we identify a concentration-dependent effect of FGF3 on thalamic axons: attractant 100 ng/mL FGF3 transforms to a repellent at high concentration 500 ng/mL. Moreover, inhibition of FGF3 guidance functions indicates that FGF3 signaling is necessary for the correct navigation of thalamic axons. Together, these studies demonstrate a direct effect for the member of FGF7 subfamily, FGF3, in the axonal pathfinding of TCAs.
Dev Neurosci

中文翻译：

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来自下丘脑的 FGF3 调节丘脑皮质轴突的导向

丘脑是一个重要的感觉中继站：除嗅觉信号外，传入的感觉信息通过丘脑皮质轴突 (TCA) 传输到大脑皮层。TCA 的途径选择取决于环境中各种可扩散或底物结合的指导线索。不仅经典的引导线索（ephrins、slits、semaphorins 和 netrins），在早期胚胎发育过程中发挥模式效应的形态发生素也可以帮助轴突在后期发育阶段导航到它们的目标。在这里，表达分析表明，在 TCA 的寻路过程中，形态原成纤维细胞生长因子 (FGF)-3 在小鸡腹侧间脑、下丘脑中表达。然后，使用小鸡外植体的体外分析，我们确定了 FGF3 对丘脑轴突的浓度依赖性影响：引诱剂 100 ng/mL FGF3 转化为高浓度 500 ng/mL 的驱虫剂。此外，FGF3 引导功能的抑制表明 FGF3 信号传导对于丘脑轴突的正确导航是必要的。总之，这些研究证明了 FGF7 亚家族成员 FGF3 在 TCA 的轴突寻路中的直接作用。
开发神经科学