Ion Channel Gradients in the Apical Tuft Region of CA1 Pyramidal Neurons
Ion Channel Gradients in the Apical Tuft Region of CA1 Pyramidal Neurons
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DOI：
10.1371/journal.pone.0046652
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发表时间：
2012-10-03
期刊：
影响因子：
3.7
通讯作者：
Magee, Jeffrey C.
中科院分区：
文献类型：
--
作者：
Bittner, Katie C.;Andrasfalvy, Bertalan K.;Magee, Jeffrey C.
树突状离子通道在形成突触输入中起关键作用，并且对于突触整合和可塑性至关重要。在海马CA 1区，AMPA受体的体-树突梯度和超极化激活的阳离子电导（I-h）抵消树突过滤对辐射层（SR）内远端Schaffer侧支（SC）突触输入的幅度、时程和时间整合的影响。虽然在CA 1远端顶端主干树突内SR的离子通道梯度已得到很好的表征，很少有人知道的离子通道表达的模式，在远端顶端簇树突内的层腔隙分子（SLM），通过穿孔路径（PP）轴突接收不同的输入从内嗅皮层。在这里，我们测量了这些远端顶端簇树突内的局部离子通道密度，以确定I-h和AMPA受体的体细胞树突梯度是否延伸到远端簇树突。我们还测定了电压门控钠通道和NMDA受体的密度。我们发现，AMPA受体，I-h，I-和电压门控钠通道的密度在SLM的簇状树突中与SR的远端顶端树突相比是相似的，而NMDA受体与AMPA受体的比率在SR内的簇状树突中相对于远端顶端树突增加。这些数据表明，顶树突中I-h和AMPA受体的体-树梯度不延伸到远端簇，并且电压门控钠通道和NMDA受体的相对密度准备支持相关SC和PP输入的非线性整合。
Dendritic ion channels play a critical role in shaping synaptic input and are fundamentally important for synaptic integration and plasticity. In the hippocampal region CA1, somato-dendritic gradients of AMPA receptors and the hyperpolarization-activated cation conductance (I-h) counteract the effects of dendritic filtering on the amplitude, time-course, and temporal integration of distal Schaffer collateral (SC) synaptic inputs within stratum radiatum (SR). While ion channel gradients in CA1 distal apical trunk dendrites within SR have been well characterized, little is known about the patterns of ion channel expression in the distal apical tuft dendrites within stratum lacunosum moleculare (SLM) that receive distinct input from the entorhinal cortex via perforant path (PP) axons. Here, we measured local ion channels densities within these distal apical tuft dendrites to determine if the somato-dendritic gradients of I-h and AMPA receptors extend into distal tuft dendrites. We also determined the densities of voltage-gated sodium channels and NMDA receptors. We found that the densities of AMPA receptors, I-h,I- and voltage-gated sodium channels are similar in tuft dendrites in SLM when compared with distal apical dendrites in SR, while the ratio of NMDA receptors to AMPA receptors increases in tuft dendrites relative to distal apical dendrites within SR. These data indicate that the somato-dendritic gradients of I-h and AMPA receptors in apical dendrites do not extend into the distal tuft, and the relative densities of voltage-gated sodium channels and NMDA receptors are poised to support nonlinear integration of correlated SC and PP input.