Abstract：
Transient expression of somatostatin (SST) has been observed in the olfactory epithelium (OE) and nerves of chick embryos. Intense expression of SST in these regions on embryonic days (E) 5-8 coincides with the migration of neurons producing gonadotropin-releasing hormone (GnRH) from the OE to the forebrain (FB), suggesting that SST plays a role in the development of GnRH neurons. Using in ovo electroporation of small interfering RNA, we found that the suppression of SST mRNA in the olfactory placode (OP) of E3.5 chick embryos significantly reduced the number of GnRH and Islet-1-immunoreactive neurons in the nasal region without affecting the entry of GnRH neurons into the FB at E5.5-6. SST knockdown did not lead to changes in the number of apoptotic, proliferating, or HuC/D-positive neuronal cells in the OE; therefore, it is possible that SST is involved in the neurogenesis/differentiation of GnRH neurons and OP-derived GnRH-negative migratory neurons. In whole OP explant cultures, we also found that SST or its analog octreotide treatment significantly increased the number of migratory GnRH neurons and the migratory distance from the explants. The co-application of an SST antagonist blocked the octreotide-induced increase in the number of GnRH neurons. Furthermore, the fasciculation of polysialylated neural cell adhesion molecule-immunoreactive fibers emerging from the explants was dependent on octreotide. Taken together, our results provide evidence that SST exerts facilitatory effects on the development of neurons expressing GnRH or Islet-1 and on GnRH neuronal migration, in addition to olfactory-related fiber fasciculation.
摘要：
在鸡胚的嗅觉上皮（OE）和神经中观察到生长抑素（SST）的瞬时表达。在胚胎（E）5-8天，这些区域中SST的强烈表达与产生促性腺激素释放激素（GnRH）的神经元从OE迁移到前脑（FB）一致，表明SST在GnRH神经元的发育中起作用。利用卵内电穿孔的小干扰RNA，我们发现在E5.5-6时,E3.5雏鸡胚胎的嗅觉胎盘(OP)中SSTmRNA的抑制显著减少了鼻区GnRH和Islet-1免疫反应性神经元的数量,而不影响GnRH神经元进入FB.SST敲低并没有导致凋亡的数量的变化，增殖,或OE中的HuC/D阳性神经元细胞；因此，SST可能参与GnRH神经元和OP衍生的GnRH阴性迁移神经元的神经发生/分化。在整个OP外植体培养中，我们还发现，SST或其类似物奥曲肽治疗显着增加了迁移的GnRH神经元的数量和与外植体的迁移距离。SST拮抗剂的共同应用阻断了奥曲肽诱导的GnRH神经元数量的增加。此外，从外植体中出现的多唾液酸化的神经细胞粘附分子-免疫反应性纤维的成束作用取决于奥曲肽。一起来看,我们的结果提供了证据，表明SST对表达GnRH或Islet-1的神经元的发育以及对GnRH神经元迁移的促进作用，除了与嗅觉相关的纤维束。
