RUI: Development and Maturation of Olfactory Centers in the Lobster: Influences of Serotonin and Adult Neurogenesis

这些研究的主要目的是通过体内和体外方法了解血清素、一氧化氮和终身神经发生如何促进嗅觉通路的发展和维持。美洲大龙虾之所以被用作实验系统，是因为它存在巨大的血清素能神经元，这些神经元从胚胎发育早期就支配嗅觉区域，而且嗅觉通路中的神经发生贯穿了动物的一生。先前的研究表明，血清素影响新生嗅觉中间神经元的增殖，促进嗅觉投射神经元的分支。此外，新生儿的投射神经元在出生后的最初几个小时内会短暂地吸收血清素。我们目前的研究有四个具体目标：1。新生儿嗅觉投射神经元瞬时5 -羟色胺摄取介导的功能将通过阻断5 -羟色胺转运体的药理学试剂来确定，同时测试对嗅觉中间神经元增殖和生长的影响。2. 对龙虾的初步研究表明，一氧化氮（NO）也可能在嗅觉通路的发育和维持中起重要作用。通过免疫细胞化学方法检测脑内NOS的时空调节来定义NO系统。此外，实验将改变一氧化氮水平，以测试对嗅觉中间神经元神经发生率的影响。3. 我们将建立一个体外系统来检验体内研究中出现的假设。本研究的目标是成功培养嗅觉中间神经元，进行三个主要实验：嗅觉投射神经元与血清素能背巨神经元共培养，将血清素引入投射神经元培养以观察其对分支的影响，并有可能直接操纵NO/cGMP通路并观察培养的投射神经元是否对NO敏感。4. 对于我们关于神经发生在嗅觉中心的发育和维持中的重要性的假设的一个测试，是在具有确定生长和确定寿命的甲壳类物种中观察这些问题。因此，我们会问，在这些物种的嗅觉区域，在终末蜕皮之前和之后，是否有持续的增殖。这些研究与高等生物的发育机制有关，因为即使在系统发育上遥远的物种中，嗅觉通路的组织和加工之间也有许多相似之处。此外，这些研究正在探索涉及神经回路发展和维持的基本机制，这可能适用于其他系统的频谱。

Beltz0091092The primary goals of these studies are to understand how serotonin, nitric oxide and life-long neurogenesis contribute to the development and maintenance of the olfactory pathway, using in vivo and in vitro methods. The lobster Homarus americanus is used as the experimental system because of the presence of giant serotonergic neurons that innervate the olfactory areas from early embryonic development, and because neurogenesis in the olfactory pathway persists throughout the animal's life. Prior studies have shown that serotonin influences the proliferation of newborn olfactory interneurons and promotes the branching of olfactory projection neurons. Additionally, newborn projection neurons transiently take up serotonin within the first few hours after their birth. There are 4 specific aims of our current studies: 1. The functions that are mediated by the transient serotonin uptake into newborn olfactory projection neurons will be defined using pharmacological agents that block the serotonin transporter, while testing for effects on proliferation and outgrowth of the olfactory interneurons. 2. Preliminary studies in the lobster suggest that nitric oxide (NO) also may be important in the development and maintenance of the olfactory pathway. The NO system will be defined by examining the temporal and spatial regulation of NOS in the brain using immunocytochemical methods. Further, NO levels will be altered experimentally in order to test for effects on the rate of neurogenesis among olfactory interneurons. 3. An in vitro system will be established to test hypotheses emerging from our in vivo studies. The goal of this effort is to successfully culture olfactory interneurons in order to perform three major experiments: to co-culture olfactory projection neurons with the serotonergic dorsal giant neuron, to introduce serotonin into cultures of projection neurons in order to visualize effects on branching, and to have the potential to directly manipulate the NO/cGMP pathway and observe whether cultured projection neurons are NO sensitive. 4. One test for our hypotheses regarding the importance of neurogenesis in the development and maintenance of olfactory centers, is to look at these issues in crustacean species that have determinate growth and a defined lifespan. We will therefore ask whether there is persistent proliferation in the olfactory areas of these species before, and then after, a terminal molt. These studies are relevant to developmental mechanisms in higher organisms because there are many parallels between the organization of olfactory pathways and processing even in phylogenetically distant species. In addition, these studies are exploring basic mechanisms involved in the development and maintenance of neural circuits, which may be applicable in a spectrum of other systems.