Rose Tobias, Gras Heribert, Hörner Michael
Institute for Zoology and Anthropology, Georg August Universität Göttingen, Berlinerstrasse 28, 37073, Göttingen, Germany.
Invert Neurosci. 2006 Dec;6(4):169-76. doi: 10.1007/s10158-006-0030-2. Epub 2006 Oct 31.
We report on factors affecting the spontaneous firing pattern of the identified serotonin-containing Retzius neurons of the medicinal leech. Increased firing activity induced by intracellular current injection is followed by a 'post-stimulus-depression' (PSD) without spiking for up to 23 s. PSD duration depends both on the duration and the amplitude of the injected current and correlates inversely with the spontaneous spiking activity. In contrast to serotonin-containing neurons in mammals, serotonin release from the Retzius cells presumably does not mediate the observed spike suppression in a self-inhibitory manner since robust PSD persists after synaptic isolation. Moreover, single additional spikes elicited at specific delays after spontaneously occurring action potentials are sufficient to significantly alter the firing pattern. Since sub-threshold current injections do not affect the ongoing spiking pattern and PSD persists in synaptically isolated preparations our data suggest that PSD reflects an endogenous and 'spike-dependent' mechanism controlling the spiking activity of Retzius cells in a use-dependent way.
我们报告了影响药用蛭中已鉴定的含5-羟色胺的雷丘斯神经元自发放电模式的因素。细胞内电流注入诱导的放电活动增加之后是长达23秒的无峰“刺激后抑制”（PSD）。PSD持续时间取决于注入电流的持续时间和幅度，并且与自发放电活动呈负相关。与哺乳动物中含5-羟色胺的神经元不同，雷丘斯细胞释放的5-羟色胺可能不会以自抑制方式介导观察到的峰抑制，因为在突触隔离后强烈的PSD仍然存在。此外，在自发发生的动作电位之后以特定延迟引发的单个额外峰足以显著改变放电模式。由于阈下电流注入不影响正在进行的放电模式，并且PSD在突触隔离的制剂中持续存在，我们的数据表明PSD反映了一种内源性的“峰依赖性”机制，以使用依赖的方式控制雷丘斯细胞的放电活动。
