Photoperiodic control of electrophysiological properties of the caudo-dorsal cells in the pond snail, Lymnaea stagnalis
Photoperiodic control of electrophysiological properties of the caudo-dorsal cells in the pond snail, Lymnaea stagnalis
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DOI：
10.1002/cne.25196
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发表时间：
2021-06-09
影响因子：
2.5
通讯作者：
Shiga, Sakiko
中科院分区：
文献类型：
--
作者：
Hamanaka, Yoshitaka;Shiga, Sakiko
在池塘蜗牛中产卵，Stagnalis是受光周期调节的;长日照条件（16 L 8D）促进产卵，而中等日照条件（12 L12 D）抑制产卵。在这种蜗牛中，尾背细胞激素（CDCH）由神经分泌细胞产生，脑神经节（CG）中的CDCs，其释放触发排卵和随后的产卵。然而，光周期依赖产卵的生理基础仍然解开。在此，我们使用细胞内记录比较了16 L 8D和12 L12 D之间的CDC的电生理特性，并且发现16 L 8D中的CDC兴奋性高于12 L12 D。显著差异如下：（1）16 L 8D的静息膜电位比12 L12 D浅，（2）16 L 8D的阈值电压（从静息到引发动作电位的最小去极化）比12 L12 D小。兴奋性的转换可以是光周期依赖性CDCH释放的生理基础。同时细胞内染料注射确定了两种形态亚型的CDC，验证了以前的报告。这两种类型承担短的横向扩展CG，其中一些可能作为光周期输入的整合网站。此外，我们发现两个新的CDCH免疫反应细胞群（CDCCOM和SCm）在CG除了传统的CDCs和小细胞表达CDCH。CDCCOM与神经血管连合中的细胞体和纤维可能参与触发排卵。值得注意的是，CDC的总数大于先前报道的，右侧CDC簇比左侧具有更多的细胞。我们的研究结果对进一步研究光周期性的神经生理学具有指导意义。stagnalis。
Egg laying in the pond snail, Lymnaea stagnalis is regulated by the photoperiod; long-day conditions (16L8D) promote egg laying whereas medium-day conditions (12L12D) suppress it. In this snail, a caudo-dorsal cell hormone (CDCH) is produced by neurosecretory cells, CDCs in the cerebral ganglion (CG), and its release triggers ovulation and subsequent egg laying. However, the physiological basis for photoperiod-dependent egg laying remains unraveled. Here, we compared electrophysiological properties of CDCs between 16L8D and 12L12D using intracellular recording, and found that CDC excitability is higher in 16L8D than in 12L12D. Striking differences are as follows: (1) a shallower resting membrane potential in 16L8D than in 12L12D, and (2) a smaller threshold voltage (minimum depolarization from rest to elicit action potentials) in 16L8D than in 12L12D. Switching of the excitability can be a physiological basis of a photoperiod-dependent CDCH release. Simultaneous intracellular dye injection identified two morphological subtypes of CDCs, validating a previous report. Both types bear short lateral extensions in CG, some of which probably function as integration sites of photoperiodic inputs. In addition, we found two novel CDCH-immunoreactive cell groups (CDCCOM and SCm) in the CG besides conventional CDCs and small cells expressing CDCH. The CDCCOM with cell bodies and fibers in the neurohemal commissure may be involved in triggering ovulation. Notably, the total number of CDCs is larger than that previously reported, the right CDC cluster with more cells than the left. Our findings are instructive in following the neurophysiology of photoperiodism in L. stagnalis.