Development And Regulation Of The Luteinizing Hormone Re

对生殖至关重要的LHRH神经元来源于鼻位并迁移到大脑，在那里它们成为下丘脑-垂体-性腺轴的组成部分。我们研究了LHRH神经元在正常/转基因动物和鼻外植体中的分化、迁移和轴突靶向的机制。利用鼻外植体、细胞系、正常动物和转基因动物，研究了LHRH神经元中LHRH基因表达、肽合成和分泌的内在和跨突触调控。本实验室前期研究发现：1)嗅轴突的生长和LHRH神经元的迁移发生在离体嗅窝组织中；2)发现了定位于鼻中线软骨组织的嗅轴突“引导线索”；3)发现GABA是鼻部LHRH神经元迁移的重要因素；4)发现了一种名为NELF的新基因。我们假设NELF通过嗜同性相互作用影响LHRH神经元在嗅轴突上的迁移。在过去的一年里，我们继续研究NELF在发育过程中的表达模式。NELF主要局限于PNS和CNS组织，在出生前和出生后都在丘脑中高度表达。我们一整年都在努力产生一种NELF基因敲除，目前正在培育嵌合动物。未来的研究旨在了解NELF在发育过程中的作用，以及由该分子激活的下游信号导致轴突生长和细胞运动。为了了解LHRH神经元的调控及其细胞反应，我们检测了鼻外植体中LHRH神经元的活性。我们发现这些细胞有重要的成熟事件，如肽产物的生物合成是这些细胞的内在特性。我们还证明，体外维持的LHRH神经元可以释放LHRH肽，并根据分泌事件快速合成新的肽。正在进行的工作主要集中在：1)分离影响嗅轴突生长的中线线索；2) NELF和其他分子在LHRH迁移中的作用，3)LHRH神经元在鼻腔外植体（不受大脑影响）中是否表现出节律性活动模式，如果是，这种节律的机制，以及4)LHRH神经元中基因的差异表达作为gaba能刺激的功能。

LHRH neurons, critical for reproduction, are derived from the nasal placode and migrate into the brain where they become integral members of the hypothalamic-pituitary-gonadal axis. We study mechanism(s) underlying LHRH neuronal differentiation, migration and axonal targeting in normal/transgenic animals, and nasal explants. Intrinsic and trans-synaptic regulation of LHRH gene expression, peptide synthesis and secretion in LHRH neurons are studied using nasal explants, cell lines and normal and transgenic animals. Previous work in our lab 1) showed that outgrowth of olfactory axons and migration of LHRH neurons occur in isolated olfactory pit tissue, 2) revealed olfactory axon 'guidance cues' localized to midline nasal cartilagenous tissue, 3) showed GABA was an important factor in the migration of LHRH neurons in nasal regions and 4) identified a novel gene termed NELF. We hypothesize NELF acts via a homophilic interaction to influence LHRH neuronal migration on olfactory axons. Over the past year, we have continued our work characterizing the expression pattern of NELF during development. NELF is primarily limited to PNS and CNS tissues, being highly expressed in the thalamus both prenatally and postnatally. We have worked throughout the year to generate a NELF knockout and currently have chimeric animals that are being bred. Future studies are directed at understanding the role of NELF during development and the downstream signals activated by this molecule that result in axon outgrowth and cell movement. To understand the regulation of LHRH neurons and their cellular responses, we examined the activity of LHRH neurons in nasal explants. We found that there are important maturational events that are intrinsic properties of these cells such as biosynthesis of peptide product. We have also demonstrated that LHRH neurons maintained in vitro can release LHRH peptide and rapidly synthesize new peptide in response to a secretory event. Work in progress is focused on: 1) isolation of the midline cues which influence olfactory axon outgrowth; 2) the role of NELF and other molecules in LHRH migration, 3) whether LHRH neurons maintained in nasal explants (devoid of brain influences) show rhythmic activity patterns and if so the mechanisms underlying this rhythm, and 4) genes differentially expressed in LHRH neurons as a function of GABAergic stimulation.