Hofer Sabine, Homberg Uwe
Fachbereich Biologie, Tierphysiologie, Philipps-Universität Marburg, 35032 Marburg, Germany.
Cell Tissue Res. 2006 Sep;325(3):589-600. doi: 10.1007/s00441-006-0155-y. Epub 2006 Apr 21.
The accessory medulla is the master circadian clock in the brain of the cockroach Leucophaea maderae and controls circadian locomotor activity. Previous studies have demonstrated that a variety of neuropeptides are prominent neuromediators in this brain area. Recently, members of the orcokinin family of crustacean neuropeptides have been identified in several insect species and shown to be widely distributed in the brain, including the accessory medulla. To investigate the possible involvement of orcokinins in circadian clock function, we have analyzed the distribution of orcokinin immunostaining in the accessory medulla of L. maderae in detail. The accessory medulla is densely innervated by approximately 30 orcokinin-immunoreactive neurons with cell bodies distributed in five of six established cell groups in the accessory medulla. Immunostaining is particularly prominent in three ventromedian neurons. These neurons have processes in a median layer of the medulla and in the internodular neuropil of the accessory medulla and send axonal fibers via the posterior optic commissure to their contralateral counterparts. Double-labeling experiments have revealed the colocalization of orcokinin immunostaining with immunoreactivity for pigment-dispersing hormone, FMRFamide, Mas-allatotropin, and gamma-aminobutyric acid in two cell groups of the accessory medulla, but not in the ventromedian neurons or in the anterior and posterior optic commissure. Immunostaining in the ventromedian neurons suggests that orcokinin-related peptides play a role in the heterolateral transmission of photic input to the pacemaker and/or in the coupling of the bilateral pacemakers of the cockroach.
附属髓质是蟑螂马德拉蜚蠊大脑中的主生物钟，控制着昼夜节律性运动活动。先前的研究表明，多种神经肽是该脑区重要的神经递质。最近，在几种昆虫物种中鉴定出了甲壳类神经肽的章鱼肽家族成员，并显示它们在大脑中广泛分布，包括附属髓质。为了研究章鱼肽可能参与生物钟功能，我们详细分析了马德拉蜚蠊附属髓质中章鱼肽免疫染色的分布情况。附属髓质由大约30个章鱼肽免疫反应性神经元密集支配，其细胞体分布在附属髓质六个既定细胞群中的五个中。免疫染色在三个腹内侧神经元中尤为突出。这些神经元在髓质的中间层和附属髓质的节间神经纤维网中有突起，并通过后视觉连合将轴突纤维发送到对侧的对应神经元。双标记实验揭示了在附属髓质的两个细胞群中，章鱼肽免疫染色与色素分散激素、FMRF酰胺、促前胸腺激素和γ-氨基丁酸的免疫反应性共定位，但在腹内侧神经元或前后视觉连合中没有。腹内侧神经元中的免疫染色表明，章鱼肽相关肽在光输入到起搏器的异侧传递和/或蟑螂双侧起搏器的耦合中起作用。
