Development And Regulation Of The Luteinizing Hormone Re

GnRH-1(也称为LHRH)神经元对生殖至关重要，它们来自鼻侧胎盘，并迁移到大脑中，在那里它们成为下丘脑-垂体-性腺轴的组成部分。我们研究了促性腺激素释放激素释放激素受体-1在正常/转基因动物和鼻腔外植体中的神经元分化、迁移和轴突靶向的机制(S)。利用这些相同的模型，我们的工作还研究了GnRH-1神经元(内在和跨突触)GnRH基因表达、多肽合成和分泌的调节机制。多种方法被用来识别和理解在引导GnRH-1神经元到达其在中枢神经系统中的最终位置方面起作用的众多分子和因素。这些包括对从迁移和非迁移细胞获得的文库的差异筛选，对迁移路线关键位置差异表达的分子的检查，对GnRH-1系统在基因敲除小鼠中发展的形态检查，以及分子在体外的扰动和随后对GnRH-1神经元运动的监测。随着GnRH-1神经元的迁移，它们也会成熟，这两个过程实际上可能是联系在一起的。为了研究GnRH-1神经元的成熟，我们用钙离子成像、电生理和生化方法检测了GnRH-1神经元的活性和多肽分泌。 在过去的一年里，我们研究了脑肠肽CCK在GnRH-1神经元发育中的作用，既作为调节神经元迁移的因子，也作为调节GnRH-1神经元活动的因子。功能分析表明，CCK抑制GnRH神经元运动，迁移停止后，下调GnRH-1神经元活性。此外，在发展中的GnRH-1系统中还检测了电压门控钙通道。我们继续研究GABA对GnRH-1神经元迁移的影响，并评估GnRH-1细胞中GABAA受体亚单位的表达作为发育的函数。这些研究表明，N型VGCC调控GnRH-1神经元迁移。已有研究对GnRH-1在门牙发育中的作用进行了研究。从这些研究中，已经鉴定了GnRH-1突变小鼠门牙的形态变化。这些研究还表明，GnRH受体在发育中的牙齿中表达，为GnRH-1的作用提供了信号转导途径。合作研究的重点是GnRH-1本身作为GnRH-1神经元活动的自分泌或旁分泌调节因子的作用。GnRH-1细胞表达GnRH-1受体，抑制GnRH-1可浓度依赖性地改变GnRH-1神经元活性。第二项合作研究检查了斑马鱼中GnRH系统的发展，以确定GnRH-1细胞是否与脊椎动物的鼻部胎盘有关。利用形态研究和活胚胎中标记的GnRH-1细胞，观察到GnRH-1细胞从鼻部胎盘区域迁移到发育中的前脑。正在进行的研究集中在NELF(a？迁徙？GnRH-1发育中的分子)、细胞因子和生长因子以及LHRH神经元迁移的原位表征(实时显微镜)。我们最近获得了我们的第一只NELF KO动物。这些小鼠是可育的，如果没有NELF，将被用来检查变化。此外，我们继续研究雌激素对GnRH-1神经元活性的作用，最近开始监测雌激素受体基因敲除小鼠产生的鼻外植体中GnRH-1神经元的活性。正在进行的研究检查与GnRH-1神经元活动相关的电特性(结合电记录和钙成像)。未来的研究旨在扩展我们目前的结果，并针对对嗅觉和GnRH-1神经元系统的发育至关重要的分子和信号，以及调节GnRH-1神经元活动的机制。正在进行的具体研究集中在：1)分离影响嗅轴突生长的中线信号；2)NELF和其他分子在GnRH-1迁移中的作用；3)确定GnRH-1神经元中参与节律活动建立/维持的起搏分子以及Kispeptin等调节分子；4)GnRH-1系统发育过程中的GABA能信号；5)雌激素改变GnRH-1神经元活动的机制。

GnRH-1 (also known as 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 GnRH-1 neuronal differentiation, migration and axonal targeting in normal/transgenic animals, and nasal explants. Using these same models, our work also addresses the mechanisms regulating (intrinsic and trans-synaptic) GnRH gene expression, peptide synthesis and secretion in GnRH-1 neurons. Multiple approaches are used to identify and understand the multitude of molecules and factors which play a role in directing the GnRH-1 neurons to their final location in the CNS. These include differential screening of libraries obtained from migrating versus non-migrating cells, examination of molecules differentially expressed at key locations along the migratory route, morphological examination of the development of the GnRH-1 system in knockout mice, and perturbation of molecules in vitro and subsequent monitoring of GnRH-1 neuronal movement. As GnRH-1 neurons migrate they also mature and the two processes may in fact be linked. To investigate the maturation of GnRH-1 neurons we use calcium imaging, electrophysiology and biochemical measures to examine GnRH-1 neuronal activity and peptide secretion. Over the past year we have investigated the role of the brain-gut peptide, CCK, in GnRH-1 neuronal development, both as a factor regulating neuronal migration and well as GnRH-1 neuronal activity. Functional analysis indicated that CCK inhibits GnRH neuronal movement and after migration has ceased, down-regulates GnRH-1 neuronal activity. In addition voltage-gated calcium channels were examined in the developing GnRH-1 system. We have continued studies on the influence of GABA on GnRH-1 neuronal migration and evaluated the GABAA receptor subunits expressed in GnRH-1 cells as a function of development. These studies indicated that the N-type VGCC modulated GnRh-1 neuronal migration. Studies have been performed to characterize, and identify the role of GnRH-1 in developing incisor. From these studies, morphological changes in the incisor of GnRH-1 mutant mice have been identified. These studies also show that the GnRH receptor is expressed in the developing tooth, providing a signal transduction pathway for GnRH-1 to act. Collaborative studies have focused on the role of GnRH-1 itself as an autocrine or paracrine regulator of GnRH-1 neuronal activity. The expression of the GnRH-1 receptor was verified on GnRH-1 cells and inhibition of GnRH-1 shown to alter GnRH-1 neuronal activity in a concentration dependent manner. A second collaborative study examined the development of the GnRH systems in zebrafish to determine whether GnRH-1 cells arise in association with the nasal placode in vertebrates. Using morphological studies as well as tagged GnRH-1 cells in live embryos, GnRH-1 cells were observed migration from the nasal placode region into the developing forebrain. Studies in progress center on the role of NELF (a ?migrational? molecule), cytokines, and growth factors in GnRH-1 development as well as in situ characterization of the migration of LHRH neurons (real time microscopy). We have recently obtained our first NELF KO animals. These mice are fertile and will be used to examine changes, if any, in the absence of NELF. In addition, we continue to study the role of estrogen on GnRH-1 neuronal activity and have recently start monitoring GnRH-1 neuronal activity in nasal explants generated from estrogen receptor knockout mice. Studies in progress examine the electrical properties associated with GnRH-1 neuronal activity (combining electrical recording and calcium imaging). Future studies are designed to expand upon our present results and are directed at the molecules and cues important for development of the olfactory and GnRH-1 neuronal systems as well as the mechanisms regulating GnRH-1 neuronal activity. Specific studies in progress focus on: 1) isolation of midline cues which influence olfactory axon outgrowth; 2) the role of NELF and other molecules in GnRH-1 migration, 3) identifying pacemaker molecules in GnRH-1 neurons that participate in establishment/maintenance of rhythmic activity as well as regulator molecules such as Kisspeptin, 4) GABAergic signals during development of the GnRH-1 system and 5) the mechanisms by which estrogen alters GnRH-1 neuronal activity.