Central and Peripheral Actions of Nitric Oxide

一氧化氮（NO）是一种小的，高活性的分子，在植物和动物中产生。它用于保护组织免受感染，并在脊椎动物的脉管系统和大多数物种的中枢神经系统（CNS）中充当信号分子。因为NO可以溶解在细胞膜和细胞周围的液体中，所以它被认为是从产生的地方广泛传播的。然而，NO信号传导的范围尚未严格定义，并且可能在组织和物种之间变化。在中枢神经系统中，200微米的有效范围将使NO能够控制数百个神经元，但在外周组织如肌肉中，该范围可能将NO限制在非常局部甚至细胞内的作用。因此，NO靶组织在大小、代谢功能和细胞结构上的巨大差异提出了关于NO信号在不同位置的机制的重要问题。建议的实验利用一个良好的特点NO信号系统在昆虫模型系统（幼虫天蛾）建立NO在中央和外周网站的功能作用。在这种昆虫中进行研究的一个关键优势是，可以在完整的、自由移动的幼虫中或在从昆虫解剖的组织中操纵信号，并在规定的条件下维持存活数小时。药理学工具可用于阻断或补充NO产生并阻断或增加其有效性。现在也有可能通过注射双链RNA在分子水平上改变完整动物体内关键酶的合成。这种治疗会干扰发育完全的动物或CNS选定部位中特定基因的表达。初步的生理实验的结果，连同解剖分布的酶，使或响应NO（一氧化氮合酶，NOS;和可溶性鸟苷酸环化酶，sGC;分别），表明NO参与控制进食（咀嚼运动和前肠活动），正常的体壁张力的调节和直接的细胞免疫反应。将使用植入正常幼虫和实验上缺乏NOS或sGC的幼虫中的电极和压力传感器记录神经和肌肉活动。NO对运动模式和神经肌肉生理学的这些作用也将在离体组织中进行检查。将通过将荧光微球植入体腔并评估正常和NO缺陷幼虫中的包裹程度来测试NO在昆虫免疫应答中的作用。预计喂养（和生长），肠道运动和体壁感觉神经元的活动都将强烈调制NO。身体膨压，运动协调和非生物封装的控制也是潜在的非常重要的网站的action.The长期目标的拟议活动是更好地了解NO如何执行其多种功能。特别是，这些结果将有助于确定NO信号在非常不同的组织环境中的专业化和局限性。由于NO参与了这种草食性昆虫的运动和摄食行为，因此该结果也可能影响用于作物保护的害虫特异性拒食剂的开发。

Nitric oxide (NO) is a small, highly reactive molecule produced in both plants and animals. It is used to protect tissues from infections and acts as a signaling molecule in the vasculature of vertebrates and the central nervous system (CNS) of most species. Because NO can dissolve in both cell membranes and the fluid around cells it is thought to spread widely from where it is produced. However, the range of NO signaling has not been rigorously defined and may vary between tissues and species. In the CNS an effective range of 200 microns would enable NO to control hundreds of neurons, but in peripheral tissues such as muscles this range could limit NO to a very local or even intracellular role. Hence, the immense differences in size, metabolic function and cellular architecture of NO target tissues raise important questions about the mechanisms of NO signaling at different locations. The proposed experiments take advantage of a well-characterized NO signaling system in an insect model system (larval Manduca sexta) to establish the functional roles of NO at central and peripheral sites. A key advantage of studies in this insect is that signaling can be manipulated in the intact, freely moving larva, or in tissues dissected from the insect and maintained alive for several hours under defined conditions. Pharmacological tools are available to block or supplement NO production and to block or increase its effectiveness. It is now also possible to alter the synthesis of key enzymes at the molecular level in intact animals using injections of double-stranded RNA. This treatment interferes with the expression of specific genes in the fully developed animal or in selected parts of the CNS. The results of preliminary physiological experiments, together with the anatomical distribution of enzymes that make or respond to NO (nitric oxide synthase, NOS; and soluble guanylyl cyclase, sGC; respectively), suggest that NO is involved in the control of feeding (chewing movements and foregut activity), the regulation of normal body wall tension and the direct cellular immune response. The neural and muscular activity will be recorded using electrodes and pressure sensors implanted in normal larvae and in larvae that are experimentally deficient in NOS or sGC. These actions of NO on motor patterns and neuromuscular physiology will also be examined pharmacologically in isolated tissues. The role of NO in the insect immune response will be tested by implanting fluorescent micro spheres into the body cavity and assessing the degree of encapsulation in normal and NO-deficient larvae. It is expected that feeding (and growth), gut movements and activity of body wall sensory neurons will all be strongly modulated by NO. The control of body turgor, motor coordination, and abiotic encapsulation are also potentially very important sites of action.The long-term goal of the proposed activity is to better understand how NO carries out its diverse functions. In particular, the results will help to define the specializations and limitations of NO signaling in very different tissue environments. Because NO is involved in the locomotion and feeding behavior of this herbivorous insect, the results could also impact the development of pest-specific antifeedants for crop protection.