Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA.
Neuroscience. 2012 Aug 16;217:67-76. doi: 10.1016/j.neuroscience.2012.04.053. Epub 2012 Apr 30.
The firing properties of dopamine (DA) neurons in the substantia nigra (SN) pars compacta are strongly influenced by the activity of apamin-sensitive small conductance Ca(2+)-activated K(+) (SK) channels. Of the three SK channel genes expressed in central neurons, only SK3 expression has been identified in DA neurons. The present findings show that SK2 was also expressed in DA neurons. Immuno-electron microscopy (iEM) showed that SK2 was primarily expressed in the distal dendrites, while SK3 was heavily expressed in the soma and, to a lesser extent, throughout the dendritic arbor. Electrophysiological recordings of the effects of the SK channel blocker apamin on DA neurons from wild type and SK(-/-) mice show that SK2-containing channels contributed to the precision of action potential (AP) timing, while SK3-containing channels influenced AP frequency. The expression of SK2 in DA neurons may endow distinct signaling and subcellular localization to SK2-containing channels.
多巴胺（DA）神经元在黑质（SN）致密部的放电特性受到 apamin 敏感的小电导钙激活钾（SK）通道活性的强烈影响。在中枢神经元中表达的三种 SK 通道基因中，只有 SK3 在 DA 神经元中被鉴定出来。本研究发现 SK2 也在 DA 神经元中表达。免疫电子显微镜（iEM）显示 SK2 主要表达在远端树突，而 SK3 在胞体中大量表达，在树突中也有一定程度的表达。对野生型和 SK（-/-）小鼠 DA 神经元中 SK 通道阻断剂 apamin 作用的电生理记录表明，含有 SK2 的通道有助于动作电位（AP）定时的精确性，而含有 SK3 的通道则影响 AP 频率。SK2 在 DA 神经元中的表达可能赋予 SK2 通道独特的信号转导和亚细胞定位。
