Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon 97239, USA.
J Neurosci. 2011 Aug 17;31(33):11825-35. doi: 10.1523/JNEUROSCI.1395-11.2011.
Multiple K(+) conductances are targets for many peripheral and central signals involved in the control of energy homeostasis. Potential K(+) channel targets are the KCNQ subunits that form the channels underlying the M-current, a subthreshold, non-inactivating K(+) current that is a common target for G-protein-coupled receptors. Whole-cell recordings were made from GFP (Renilla)-tagged neuropeptide Y (NPY) neurons from the arcuate nucleus of the hypothalamus using protocols to isolate and characterize the M-current in these orexigenic neurons. We recorded robust K(+) currents in the voltage range of the M-current, which were inhibited by the selective KCNQ channel blocker 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone dihydrochloride (XE991) (40 μm), in both intact males and ovariectomized, 17β-estradiol (E2)-treated females. Since NPY neurons are orexigenic and are active during fasting, the M-current was measured in fed and fasted male mice. Fasting attenuated the XE991-sensitive current by threefold, which correlated with decreased expression of the KCNQ2 and KCNQ3 subunits as measured with quantitative real-time PCR. Furthermore, E2 treatment augmented the XE991-sensitive M-current by threefold in ovariectomized (vs oil-treated) female mice. E2 treatment increased the expression of the KCNQ5 subunit in females but not KCNQ2 or KCNQ3 subunits. Fasting in females abrogated the effects of E2 on M-current activity, at least in part, by decreasing KCNQ2 and KCNQ3 expression. In summary, these data suggest that the M-current plays a pivotal role in the modulation of NPY neuronal excitability and may be an important cellular target for neurotransmitter and hormonal signals in the control of energy homeostasis in both males and females.
多种 K(+)电导是许多参与能量稳态控制的外围和中枢信号的作用靶点。潜在的 K(+)通道靶点是形成 M 电流的 KCNQ 亚基，M 电流是一种亚阈值、非失活的 K(+)电流，是 G 蛋白偶联受体的常见靶点。使用分离和表征这些食欲神经元中 M 电流的方案，从下丘脑弓状核的 GFP（雷尼娜）标记神经肽 Y（NPY）神经元中进行全细胞记录。我们在 M 电流的电压范围内记录到了强大的 K(+)电流，该电流被选择性 KCNQ 通道阻断剂 10,10-双（4-吡啶基甲基）-9(10H)-蒽酮二盐酸盐（XE991）（40 μm）抑制，在完整雄性和去卵巢、17β-雌二醇（E2）处理的雌性中均如此。由于 NPY 神经元是食欲亢进的，并且在禁食期间活跃，因此在进食和禁食的雄性小鼠中测量了 M 电流。禁食使 XE991 敏感电流降低三倍，这与定量实时 PCR 测量的 KCNQ2 和 KCNQ3 亚基表达减少相关。此外，E2 处理使去卵巢（与油处理相比）雌性小鼠中的 XE991 敏感 M 电流增加三倍。E2 处理增加了雌性小鼠中 KCNQ5 亚基的表达，但不增加 KCNQ2 或 KCNQ3 亚基。禁食至少部分通过降低 KCNQ2 和 KCNQ3 表达，消除了 E2 对 M 电流活性的影响。总之，这些数据表明，M 电流在调节 NPY 神经元兴奋性方面起着关键作用，并且可能是男性和女性中神经递质和激素信号控制能量稳态的重要细胞靶点。
