Fuchs Jason R, Darlington Shelby W, Green John T, Morielli Anthony D
Department of Psychological Science, University of Vermont, Burlington, VT 05405, United States.
Department of Pharmacology, University of Vermont, Burlington, VT 05405, United States.
Neurobiol Learn Mem. 2017 Jul;142(Pt B):252-262. doi: 10.1016/j.nlm.2017.05.009. Epub 2017 May 13.
Numerous experiments using ex vivo electrophysiology suggest that mammalian learning and memory involves regulation of voltage-gated ion channels in terms of changes in function. Yet, little is known about learning-related regulation of voltage-gated ion channels in terms of changes in expression. In two experiments, we examined changes in cell surface expression of the voltage-gated potassium channel alpha-subunit Kv1.2 in a discrete region of cerebellar cortex after eyeblink conditioning (EBC), a well-studied form of cerebellar-dependent learning. Kv1.2 in cerebellar cortex is expressed almost entirely in basket cells, primarily in the axon terminal pinceaux (PCX) region, and Purkinje cells, primarily in dendrites. Cell surface expression of Kv1.2 was measured using both multiphoton microscopy, which allowed measurement confined to the PCX region, and biotinylation/western blot, which measured total cell surface expression. In the first experiment, rats underwent three sessions of EBC, explicitly unpaired stimulus exposure, or context-only exposure and the results revealed a decrease in Kv1.2 cell surface expression in the unpaired group as measured with microscopy but no change as measured with western blot. In the second experiment, the same three training groups underwent only one half of a session of training, and the results revealed an increase in Kv1.2 cell surface expression in the unpaired group as measured with western blot but no change as measured with microscopy. In addition, rats in the EBC group that did not express conditioned responses (CRs) exhibited the same increase in Kv1.2 cell surface expression as the unpaired group. The overall pattern of results suggests that cell surface expression of Kv1.2 is changed with exposure to EBC stimuli in the absence, or prior to the emergence, of CRs.
大量使用离体电生理学的实验表明，哺乳动物的学习和记忆在功能变化方面涉及电压门控离子通道的调节。然而，关于电压门控离子通道在表达变化方面与学习相关的调节却知之甚少。在两项实验中，我们研究了眨眼条件反射（EBC）后，小脑皮质离散区域中电压门控钾通道α亚基Kv1.2的细胞表面表达变化。EBC是一种经过充分研究的小脑依赖性学习形式。小脑皮质中的Kv1.2几乎完全表达于篮状细胞中，主要在轴突终末篮（PCX）区域，以及浦肯野细胞中，主要在树突中。使用多光子显微镜（可将测量局限于PCX区域）和生物素化/蛋白质印迹法（可测量总细胞表面表达）来测量Kv1.2的细胞表面表达。在第一个实验中，大鼠接受了三个阶段的EBC、明确的非配对刺激暴露或仅情境暴露，结果显示，用显微镜测量时，非配对组中Kv1.2细胞表面表达减少，但用蛋白质印迹法测量时无变化。在第二个实验中，相同的三个训练组只进行了一半的训练阶段，结果显示，用蛋白质印迹法测量时，非配对组中Kv1.2细胞表面表达增加，但用显微镜测量时无变化。此外，EBC组中未表现出条件反应（CR）的大鼠，其Kv1.2细胞表面表达的增加与非配对组相同。结果的总体模式表明，在没有CR或CR出现之前，暴露于EBC刺激会改变Kv1.2的细胞表面表达。
