Herbert Zsofia, Rauser Sandra, Williams Leslie, Kapan Neval, Güntner Michaela, Walch Axel, Boyan George
Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, 82152 Martinsried, Germany.
J Morphol. 2010 Dec;271(12):1509-26. doi: 10.1002/jmor.10895.
The central complex is a major integrative region within the insect brain with demonstrated roles in spatial orientation, the regulation of locomotor behavior, and sound production. In the hemimetabolous grasshopper, the central complex comprises the protocerebral bridge, central body (CB), ellipsoid body, noduli, and accessory lobes, and this modular organization develops entirely during embryogenesis. From a biochemical perspective, a range of neuroactive substances has been demonstrated in these modules of the adult central complex, but little is known about their developmental expression. In this study, we use matrix-assisted laser desorption/ionization-imaging mass spectrometry on single brain slices to confirm the presence of several peptide families (tachykinin, allatostatin, periviscerokinin/pyrokinin, FLRFamide, and neuropeptide F) in the adult central complex and then use immunohistochemistry and histology to examine their developmental expression, together with that of the indolamin serotonin, and the endogenous messenger nitric oxide (NO; via its synthesizing enzyme). We find that each neuromodulator is expressed according to a unique, stereotypic, pattern within the various modules making up the central complex. Neuropeptides such as tachykinin (55%) and allatostatin (65%), and the NO-synthesizing enzyme diaphorase (70%), are expressed earlier during embryonic development than the biogenic amine serotonin (80%), whereas periviscerokinin-like peptides and FLRFamide-like peptides begin to be expressed only postembryonically. Within the CB, these neuroactive substances are present in tangential projection neurons before they appear in columnar neurons. There is also no colocalization of serotonin-positive and peptide-positive projections up to the third larval instar during development, consistent with the clear dorsoventral layering of the neuropil we observe. Our results provide the first neurochemical fingerprint of the developing central complex in an hemimetabolous insect.
中央复合体是昆虫大脑内一个主要的整合区域，在空间定向、运动行为调节和发声方面发挥着作用。在渐变态蚱蜢中，中央复合体由原脑桥、中央体（CB）、椭球体、小结和副叶组成，这种模块化组织在胚胎发育过程中完全形成。从生化角度来看，在成年中央复合体的这些模块中已证实存在一系列神经活性物质，但对它们的发育表达了解甚少。在本研究中，我们对单个脑切片进行基质辅助激光解吸/电离成像质谱分析，以确认成年中央复合体中存在几个肽家族（速激肽、咽侧体抑制素、围脏激肽/焦激肽、FLRF酰胺和神经肽F），然后使用免疫组织化学和组织学方法来研究它们以及吲哚胺5-羟色胺和内源性信使一氧化氮（NO；通过其合成酶）的发育表达。我们发现，每种神经调质在构成中央复合体的各个模块中都按照独特的、刻板的模式表达。神经肽如速激肽（55%）和咽侧体抑制素（65%），以及NO合成酶黄递酶（70%），在胚胎发育早期比生物胺5-羟色胺（80%）表达得更早，而围脏激肽样肽和FLRF酰胺样肽仅在胚胎后期开始表达。在中央体内，这些神经活性物质在切向投射神经元中出现之前就存在于柱状神经元中。在发育过程中，直到第三龄幼虫期，5-羟色胺阳性和肽阳性投射也没有共定位现象，这与我们观察到的神经纤维网明显的背腹分层一致。我们的结果提供了渐变态昆虫发育中的中央复合体的首个神经化学图谱。
