RUI: Nitric Oxide Inhibition of Molluscan Metamorphosis

神经递质通常是由激活的神经细胞释放的小分子，使其能够与其他神经元进行通信。大多数神经递质储存在囊泡中，当神经元受到电刺激时，它们会在短时间内释放出来。释放后，这些分子通过狭窄的突触间隙扩散，并与靶细胞的表面受体相互作用。在过去的15年里，一类新的神经递质以一种不同的方式被发现。这些气态神经递质，包括一氧化氮和一氧化碳，可以根据需要通过酶合成，并可以通过细胞和组织扩散，与细胞内生化途径相互作用。在这两种气体中，人们对一氧化氮的功能以及它在成人神经系统中的作用了解得更多。例如，一氧化氮在行为攻击、学习和记忆以及嗅觉反应的调解等多种系统中发挥作用。然而，这种分子在神经系统发育中的功能仍在阐明中。Leise博士研究的初步数据表明，一氧化氮可能在发育中的神经系统中作为一种天然的变态抑制剂起作用。释放后，一氧化氮通常与guanyyl环化酶相互作用，增强细胞内信使分子cGMP的产生，这反过来可以影响广泛的细胞生物化学。为了确定典型的一氧化氮-胍基环化酶途径是否是控制变态的细胞系统的一部分，Leise博士和她的同事将对一种海洋蜗牛进行一系列相关实验。他们将使用药理学实验来阻止一氧化氮的产生，一氧化氮可以使变态继续进行。他们将使用生化分析来测量变形之前、过程中和之后的cGMP水平，他们还将使用免疫细胞化学程序来确定哪些细胞产生一氧化氮，哪些细胞可能是含有guanyyl环化酶的目标。这些研究将确定一氧化氮是否在控制变态发病中起重要作用。甚至人类在青春期经历的荷尔蒙变化中也保留着变态的痕迹，这种新的气态神经递质可能在这一重要的发育过程中发挥了作用。

ABSTRACT IBN 9604516 LEISE Neurotransmitters are typically small molecules that are released by an activated nerve cell, allowing it to communicate with other neurons. Most neurotransmitters are stored within vesicles and released for short periods of time when a neuron is electrically excited. Upon release, these molecules diffuse across a narrow synaptic cleft and interact with surface receptors on their target cells. In the last 15 years, a new class of neurotransmitters has been identified that acts in a different fashion. These gaseous neurotransmitters, including nitric oxide and carbon monoxide, are made enzymatically upon demand, and can diffuse through cells and tissues to interact with intracellular biochemical pathways. Of these two gases, more is known about the functions of nitric oxide and how it acts in adult nervous systems. For example, nitric oxide plays roles in systems as diverse as behavioral aggression, learning and memory, and the mediation of olfactory responses. The functions of this molecule in developing nervous systems are, however, still being elucidated. Preliminary data from Dr. Leise's research have indicated that nitric oxide may act within developing nervous systems as a natural inhibitor of metamorphosis. Upon release, nitric oxide typically interacts with the enzyme guanylyl cyclase to enhance production of the intracellular messenger molecule cGMP, which in turn can affect a broad range of cellular biochemistry. To determine if the typical nitric oxide-guanylyl cyclase pathway is part of the cellular systems that control metamorphosis, Dr. Leise and her coworkers will conduct a series of related experiments on a species of marine snails. They will use pharmacological experiments to block the production of nitric oxide, which should allow metamorphosis to proceeed. They will use biochemical assays to measure levels of cGMP before, during and after metamorphosis, and they will also use immunocytochemical procedures to determine which cells prod uce nitric oxide and which cells are the likely targets that contain the enzyme guanylyl cyclase. These investigations will determine whether or not nitric oxide plays an important role in governing the onset of metamorphosis. Even humans retain vestiges of metamorphosis in the hormonal changes that we undergo during puberty, and it may be that this new gaseous neurotransmitter plays a role in this important developmental process.