Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, USA.
J Neurophysiol. 2013 Apr;109(7):1940-53. doi: 10.1152/jn.00010.2013. Epub 2013 Jan 16.
The rodent hippocampus can be divided into dorsal (DHC) and ventral (VHC) domains on the basis of behavioral, anatomical, and biochemical differences. Recently, we reported that CA1 pyramidal neurons from the VHC were intrinsically more excitable than DHC neurons, but the specific ionic conductances contributing to this difference were not determined. Here we investigated the hyperpolarization-activated current (I(h)) and the expression of HCN1 and HCN2 channel subunits in CA1 pyramidal neurons from the DHC and VHC. Measurement of Ih with cell-attached patches revealed a significant depolarizing shift in the V(1/2) of activation for dendritic h-channels in VHC neurons (but not DHC neurons), and ultrastructural immunolocalization of HCN1 and HCN2 channels revealed a significantly larger HCN1-to-HCN2 ratio for VHC neurons (but not DHC neurons). These observations suggest that a shift in the expression of HCN1 and HCN2 channels drives functional changes in I(h) for VHC neurons (but not DHC neurons) and could thereby significantly alter the capacity for dendritic integration of these neurons.
基于行为、解剖和生化差异，啮齿动物海马可分为背侧（DHC）和腹侧（VHC）两个区域。最近，我们报道 VHC 的 CA1 锥体神经元内在兴奋性高于 DHC 神经元，但导致这种差异的具体离子电导尚未确定。本研究旨在探讨 DHC 和 VHC 的 CA1 锥体神经元中的超极化激活电流（I(h)）和 HCN1 和 HCN2 通道亚基的表达。通过细胞贴附式膜片钳记录 I(h)，发现 VHC 神经元（而非 DHC 神经元）树突 h 通道的激活 V(1/2) 出现显著去极化偏移，而 HCN1 和 HCN2 通道的超微结构免疫定位显示 VHC 神经元（而非 DHC 神经元）的 HCN1 与 HCN2 通道比值显著增大。这些观察结果表明，HCN1 和 HCN2 通道表达的改变驱动了 VHC 神经元（而非 DHC 神经元）I(h)的功能变化，从而可能显著改变这些神经元的树突整合能力。
