Schneider Nils-Lasse, Stengl Monika
Department of Biology, Animal Physiology, Philipps University of Marburg, D-35032 Marburg, Germany.
J Neurosci. 2005 May 25;25(21):5138-47. doi: 10.1523/JNEUROSCI.5138-A-04.2005.
Pigment-dispersing factor-immunoreactive circadian pacemaker cells, which arborize in the accessory medulla, control circadian locomotor activity rhythms in Drosophila as well as in the cockroach Leucophaea maderae via unknown mechanisms. Here, we show that circadian pacemaker candidates of the accessory medulla of the cockroach produce regular interspike intervals. Therefore, the membrane potential of the cells oscillates with ultradian periods. Most or all oscillating cells within the accessory medulla are coupled via synaptic and nonsynaptic mechanisms, forming different assemblies. The cells within an assembly share the same ultradian period (interspike interval) and the same phase (timing of spikes), whereas cells between assemblies differ in phase. Apparently, the majority of these assemblies are formed by inhibitory GABAergic synaptic interactions. Application of pigment-dispersing factor phase locked and thereby synchronized different assemblies. The data suggest that pigment-dispersing factor inhibits GABAergic interneurons, resulting in disinhibition and phase locking of their postsynaptic cells, which previously belonged to different assemblies. Our data suggest that phase control of action potential oscillations in the ultradian range is a main task of the circadian pacemaker network. We hypothesize that neuropeptide-dependent phase control is used to gate circadian outputs to locomotor control centers.
在果蝇以及蟑螂马德拉蜚蠊中，在副髓质形成分支的色素分散因子免疫反应性昼夜节律起搏器细胞，通过未知机制控制昼夜运动活动节律。在此，我们表明蟑螂副髓质的昼夜节律起搏器候选细胞产生规则的峰间期。因此，细胞的膜电位以超日周期振荡。副髓质内的大多数或所有振荡细胞通过突触和非突触机制耦合，形成不同的集合。一个集合内的细胞具有相同的超日周期（峰间期）和相同的相位（峰的时间），而不同集合之间的细胞相位不同。显然，这些集合中的大多数是由抑制性GABA能突触相互作用形成的。色素分散因子的应用使不同集合锁相并同步。数据表明，色素分散因子抑制GABA能中间神经元，导致其突触后细胞去抑制和锁相，这些突触后细胞先前属于不同的集合。我们的数据表明，超日范围内动作电位振荡的相位控制是昼夜节律起搏器网络的主要任务。我们假设神经肽依赖性相位控制用于将昼夜节律输出传递到运动控制中心。
