Whitlock K E, Illing N, Brideau N J, Smith K M, Twomey S
Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY 14853, United States.
Mol Cell Endocrinol. 2006 Jul 25;254-255:39-50. doi: 10.1016/j.mce.2006.04.038. Epub 2006 Jun 13.
Cells containing gonadotropin-releasing hormone (GnRH) are essential not only for reproduction but also for neuromodulatory functions in the adult animal. A variety of studies have hinted at multiple origins for GnRH-containing cells in the developing embryo. We have shown, using zebrafish as a model system, that GnRH cells originate from precursors lying outside the olfactory placode: the region of the anterior pituitary gives rise to hypothalamic GnRH cells and the cranial neural crest gives rise to the GnRH cells of the terminal nerve and midbrain. Cells of both the forming anterior pituitary and cranial neural crest are closely apposed to the precursors of the olfactory epithelium during early development. Disruption of kallmann gene function results in loss of the hypothalamic but not the terminal nerve GnRH cells during early development. The GnRH proteins are expressed early in development and this expression is mirrored by the onset of GnRH receptor (GnRH-R) expression during early development. Thus the signaling of the GnRH neuronal circuitry is set up early in development laying the foundation for the GnRH network that is activated at puberty leading to reproductive function in the mature animal.
含有促性腺激素释放激素（GnRH）的细胞不仅对成年动物的繁殖至关重要，而且对其神经调节功能也很重要。各种研究暗示了发育中胚胎中含GnRH细胞的多种起源。我们以斑马鱼为模型系统表明，GnRH细胞起源于嗅基板外的前体：垂体前部区域产生下丘脑GnRH细胞，颅神经嵴产生终末神经和中脑的GnRH细胞。在早期发育过程中，正在形成的垂体前部和颅神经嵴的细胞都与嗅上皮的前体紧密相邻。卡尔曼基因功能的破坏导致早期发育过程中下丘脑GnRH细胞而非终末神经GnRH细胞的缺失。GnRH蛋白在发育早期表达，这种表达在早期发育过程中GnRH受体（GnRH-R）表达开始时得到反映。因此，GnRH神经元回路的信号在发育早期就建立起来，为青春期激活的GnRH网络奠定了基础，该网络导致成熟动物的生殖功能。
