Krenz Wulf-Dieter, Parker Anna R, Rodgers Edmund, Baro Deborah J
Department of Biology, Georgia State University Atlanta, GA, USA.
Front Neural Circuits. 2015 Oct 20;9:63. doi: 10.3389/fncir.2015.00063. eCollection 2015.
Experimental and computational studies demonstrate that different sets of intrinsic and synaptic conductances can give rise to equivalent activity patterns. This is because the balance of conductances, not their absolute values, defines a given activity feature. Activity-dependent feedback mechanisms maintain neuronal conductance correlations and their corresponding activity features. This study demonstrates that tonic nM concentrations of monoamines enable slow, activity-dependent processes that can maintain a correlation between the transient potassium current (I(A) and the hyperpolarization activated current (Ih) over the long-term (i.e., regulatory change persists for hours after removal of modulator). Tonic 5 nM DA acted through an RNA interference silencing complex (RISC)- and RNA polymerase II-dependent mechanism to maintain a long-term positive correlation between I(A) and Ih in the lateral pyloric neuron (LP) but not in the pyloric dilator neuron (PD). In contrast, tonic 5 nM 5HT maintained a RISC-dependent positive correlation between I(A) and Ih in PD but not LP over the long-term. Tonic 5 nM OCT maintained a long-term negative correlation between I(A) and Ih in PD but not LP; however, it was only revealed when RISC was inhibited. This study also demonstrated that monoaminergic tone can also preserve activity features over the long-term: the timing of LP activity, LP duty cycle and LP spike number per burst were maintained by tonic 5 nM DA. The data suggest that low-level monoaminergic tone acts through multiple slow processes to permit cell-specific, activity-dependent regulation of ionic conductances to maintain conductance correlations and their corresponding activity features over the long-term.
实验和计算研究表明，不同的内在和突触电导集可产生等效的活动模式。这是因为电导的平衡而非其绝对值定义了给定的活动特征。活动依赖的反馈机制维持神经元电导相关性及其相应的活动特征。本研究表明，纳摩尔浓度的单胺能够实现缓慢的、活动依赖的过程，从而在长期内维持瞬时钾电流（I(A)）和超极化激活电流（Ih）之间的相关性（即，在去除调节剂后，调节性变化持续数小时）。5纳摩尔的多巴胺（DA）通过RNA干扰沉默复合体（RISC）和RNA聚合酶II依赖的机制，在外侧幽门神经元（LP）而非幽门扩张神经元（PD）中维持I(A)和Ih之间的长期正相关。相反，5纳摩尔的5-羟色胺（5HT）在长期内维持PD而非LP中I(A)和Ih之间的RISC依赖的正相关。5纳摩尔的章鱼胺（OCT）在PD而非LP中维持I(A)和Ih之间的长期负相关；然而，只有在RISC被抑制时才会显现。本研究还表明，单胺能张力也能在长期内保持活动特征：5纳摩尔的DA维持了LP活动的时间、LP占空比和每次爆发的LP尖峰数量。数据表明，低水平的单胺能张力通过多个缓慢过程起作用，以允许对离子电导进行细胞特异性的、活动依赖的调节，从而在长期内维持电导相关性及其相应的活动特征。
