Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.
Dev Dyn. 2010 Oct;239(10):2637-46. doi: 10.1002/dvdy.22412.
Brain-derived neurotrophic factor (BDNF), neurotrophin-4 (NT4), and their TrkB receptor regulate taste system development. To determine where and when gustatory neurons come in contact with these important factors, temporospatial expression patterns of Bdnf, Ntf4/5, and TrkB in the peripheral taste system were examined using RT-PCR. In the lingual epithelium, Ntf4/5 mRNA expression was higher than that of Bdnf at embryonic day 12.5 (E12.5), and the expression of both factors decreased afterwards. However, Ntf4/5 expression decreased at an earlier age than Bdnf. Bdnf and Ntf4/5 are expressed in equal amounts at E12.5 in geniculate ganglion, but Bdnf expression increased from E14.5 to birth, whereas Ntf4/5 expression decreased. These findings indicate that NT4 functions at early embryonic stages and is derived from different sources than Bdnf. TrkB expression in the geniculate ganglion is robust throughout development and is not a limiting factor for neurotrophin function in this system.
脑源性神经营养因子（BDNF）、神经营养因子-4（NT4）及其 TrkB 受体调节味觉系统的发育。为了确定味觉神经元何时何地与这些重要因子接触，使用 RT-PCR 检查了外周味觉系统中 Bdnf、Ntf4/5 和 TrkB 的时空表达模式。在舌上皮中，Ntf4/5 mRNA 的表达在胚胎第 12.5 天（E12.5）高于 Bdnf，之后两种因子的表达都下降。然而，Ntf4/5 的表达下降比 Bdnf 更早。在 E12.5 时，BDNF 和 Ntf4/5 在膝状神经节中表达量相等，但 Bdnf 的表达从 E14.5 到出生时增加，而 Ntf4/5 的表达下降。这些发现表明 NT4 在早期胚胎阶段发挥作用，并且其来源与 Bdnf 不同。TrkB 在膝状神经节中的表达在整个发育过程中都很强烈，并且不是该系统中神经营养因子功能的限制因素。
