Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri 65211.
Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri 65211
eNeuro. 2024 Nov 13;11(11). doi: 10.1523/ENEURO.0320-24.2024. Print 2024 Nov.
Relationships among membrane currents allow central pattern generator (CPG) neurons to reliably drive motor programs. We hypothesize that continually active CPG neurons utilize activity-dependent feedback to correlate expression of ion channel genes to balance essential membrane currents. However, episodically activated neurons experience absences of activity-dependent feedback and, thus, presumably employ other strategies to coregulate the balance of ionic currents necessary to generate appropriate output after periods of quiescence. To investigate this, we compared continually active pyloric dilator (PD) neurons with episodically active lateral gastric (LG) CPG neurons of the stomatogastric ganglion (STG) in male crabs. After experimentally activating LG for 8 h, we measured three potassium currents and abundances of their corresponding channel mRNAs. We found that ionic current relationships were correlated in LG's silent state, but ion channel mRNA relationships were correlated in the active state. In continuously active PD neurons, ion channel mRNAs and ionic currents are simultaneously correlated. Therefore, two distinct relationships exist between channel mRNA abundance and the ionic current encoded in these cells: in PD, a direct correlation exists between channel mRNA levels and the A-type potassium current it carries. Conversely, such channel mRNA-current relationships are not detected and appear to be temporally uncoupled in LG neurons. Our results suggest that ongoing feedback maintains membrane current and channel mRNA relationships in continually active PD neurons, while in LG neurons, episodic activity serves to establish channel mRNA relationships necessary to produce the ionic current profile necessary for the next bout of activity.
膜电流之间的关系使中枢模式发生器（CPG）神经元能够可靠地驱动运动程序。我们假设持续活跃的 CPG 神经元利用活动依赖性反馈来将离子通道基因的表达与平衡基本膜电流相关联。然而，间歇性激活的神经元经历活动依赖性反馈的缺失，因此，可能采用其他策略来共同调节在静止期后产生适当输出所需的离子电流平衡。为了研究这一点，我们比较了雄性 螃蟹的口胃窦神经节（STG）中的持续活跃的幽门扩张（PD）神经元与间歇性活跃的外侧胃（LG）CPG 神经元。在实验性地激活 LG 8 小时后，我们测量了三种钾电流及其相应通道 mRNA 的丰度。我们发现，在 LG 的静止状态下，离子电流关系是相关的，但在活跃状态下，离子通道 mRNA 关系是相关的。在持续活跃的 PD 神经元中，离子通道 mRNA 和离子电流同时相关。因此，通道 mRNA 丰度与这些细胞中编码的离子电流之间存在两种不同的关系：在 PD 中，通道 mRNA 水平与其携带的 A 型钾电流之间存在直接相关性。相反，在 LG 神经元中，没有检测到这种通道 mRNA-电流关系，并且它们似乎在时间上是解耦的。我们的结果表明，持续的反馈维持了持续活跃的 PD 神经元中的膜电流和通道 mRNA 关系，而在 LG 神经元中，间歇性活动用于建立产生下一轮活动所需的离子电流特征的必要的通道 mRNA 关系。
