Organization of the procerebrum in terrestrial pulmonates (Helix, Limax) reconsidered: cell mass layer synaptology and its serotonergic input system
Organization of the procerebrum in terrestrial pulmonates (Helix, Limax) reconsidered: cell mass layer synaptology and its serotonergic input system
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DOI：
10.1007/s00429-012-0409-2
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发表时间：
2013-03-01
影响因子：
3.1
通讯作者：
Ito, Etsuro
中科院分区：
文献类型：
--
作者：
Elekes, Karoly;Battonyai, Izabella;Ito, Etsuro
研究了两种主要的陆生肺腹足动物——双头腹足动物（Helix pomatia）和大腹足动物（Limax valentianus）嗅觉中心-前脑细胞体层的突触结构。此外，在高分辨率下进行了5- ht免疫反应性神经支配的分析，包括超微结构水平。在这两个物种的前脑中发现了一个高度复杂的突触和非突触连接系统，连接着不同大小的局部神经区域。核周前脑（球）细胞有丰富的神经支配，轴突分布也相互联系。突触结构包括收敛、发散和突触前调制。与递质释放的调节形式相关的非特化但密切的轴-体细胞和轴-轴突膜接触的频繁发生也伴随着表明活跃胞外分泌的膜构型。在pomatia中，细胞团层受到丰富的5- ht免疫反应性神经支配，在细胞体周围形成密集的网络。在超微结构水平上，5- ht免疫反应性静脉曲张与细胞体和不同未标记的轴突轮廓均有接触。我们的研究结果表明，细胞体层的局部神经区是局部电路的所在地，可能在与前脑结合的嗅觉整合过程中起决定性作用。外源性5- ht免疫反应性神经支配的模式和形式表明在细胞体层中具有整体调节作用。该结果可能为考虑与微电路相关的局部细胞间事件在前脑细胞体层内参与振荡活动的作用提供基础。
The synaptology of the cell body layer of the olfactory center, procerebrum, was investigated in two prominent terrestrial pulmonate gastropod species, Helix pomatia and Limax valentianus. In addition, the analysis of the 5-HT-immunoreactive innervation, including ultrastructural level, was performed at high resolution in H. pomatia. A highly complex system of synaptic and non-synaptic connections was found in the procerebrum of both species connected to local neuropil areas of different size. The procerebral (globuli) cell perikarya were richly innervated by varicosities meanwhile the axon profiles also established contacts with each other. Synaptic configurations including convergence, divergence and presynaptic modulation were also revealed. The frequent occurrence of unspecialized but close axo-somatic and axo-axonic membrane contacts referring to the modulatory forms of transmitter release were also accompanied by membrane configurations indicative of active exocytosis. In H. pomatia, the cell mass layer was shown to receive a rich 5-HT-immunoreactive innervation, forming a dense network around the cell bodies. At ultrastructural level, 5-HT-immunoreactive varicosities contacted both cell bodies and different unlabeled axon profiles. Our results suggest that the local neuropil regions in the cell body layer are site of local circuits, which may play a decisive role in olfactory integrative processes bound to the procerebrum. The pattern and form of the 5-HT-immunoreactive innervation of extrinsic origin suggest an overall modulatory role in the cell body layer. The results may serve a basis for considering the role of local intercellular events, connected to microcircuits, within the procerebrum cell body layer involved in oscillation activities.