Fujisawa Y, Furukawa Y, Ohta S, Ellis T A, Dembrow N C, Li L, Floyd P D, Sweedler J V, Minakata H, Nakamaru K, Morishita F, Matsushima O, Weiss K R, Vilim F S
Suntory Institute for Bioorganic Research, Shimamoto, Mishima, Osaka 618-8503, Japan.
J Neurosci. 1999 Nov 1;19(21):9618-34. doi: 10.1523/JNEUROSCI.19-21-09618.1999.
Neuropeptides are a ubiquitous class of signaling molecules. In our attempt to understand the generation of feeding behavior in Aplysia, we have sought to identify and fully characterize the neuropeptides operating in this system. Preliminary evidence indicated that Mytilus inhibitory peptide (MIP)-like peptides are present and operating in the circuitry that generates feeding in Aplysia. MIPs were originally isolated from the bivalve mollusc Mytilus edulis, and related peptides have been identified in other invertebrate species, but no precursor has been identified. In this study, we describe the isolation and characterization of novel Aplysia MIP-related peptides (AMRPs) and their precursor. Several AMRPs appear to have some structural and functional features similar to vertebrate opioid peptides. We use matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to confirm that all 14 AMRPs predicted by the precursor are processed in isolated neurons. Northern analysis, whole-mount in situ hybridization, and immunohistochemistry are used to map the abundant expression of these peptides in the CNS and peripheral tissues such as the digestive tract, vasculature, and the reproductive organs. Physiological studies demonstrate that the rank order of the inhibitory actions of these peptides is different for three target muscles. These results underscore the importance of using a multidisciplinary approach to identifying and characterizing the actions of neuropeptides in an effort to gain understanding of their role in systems of interest. The widespread distribution of the AMRPs indicates that they may be operating in many different systems of Aplysia.
神经肽是一类普遍存在的信号分子。在我们试图理解海兔进食行为的产生过程中，我们一直致力于识别并全面表征在该系统中起作用的神经肽。初步证据表明，贻贝抑制肽（MIP）样肽存在于海兔产生进食行为的神经回路中并发挥作用。MIP最初是从双壳贝类贻贝中分离出来的，并且在其他无脊椎动物物种中也鉴定出了相关肽，但尚未鉴定出其前体。在本研究中，我们描述了新型海兔MIP相关肽（AMRP）及其前体的分离和表征。几种AMRP似乎具有一些与脊椎动物阿片样肽相似的结构和功能特征。我们使用基质辅助激光解吸/电离飞行时间质谱法来确认前体预测的所有14种AMRP在分离的神经元中都得到了加工。Northern分析、整体原位杂交和免疫组织化学被用于绘制这些肽在中枢神经系统和外周组织（如消化道、脉管系统和生殖器官）中的丰富表达图谱。生理学研究表明，这些肽对三种目标肌肉的抑制作用的强度顺序不同。这些结果强调了采用多学科方法来识别和表征神经肽作用的重要性，以便了解它们在感兴趣的系统中的作用。AMRP的广泛分布表明它们可能在海兔的许多不同系统中发挥作用。
