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首页> 外文期刊>Journal of Neurophysiology >Molecular identity, ontogeny, and cAMP modulation of the hyperpolarizationactivated current in vestibular ganglion neurons
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Molecular identity, ontogeny, and cAMP modulation of the hyperpolarizationactivated current in vestibular ganglion neurons

机译：前庭神经节神经元超极化激活电流的分子同一性，本体论和cAMP调节

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Properties, developmental regulation, and cAMP modulation of the hyperpolarization-activated current (I_n) were investigated by the whole cell patch-clamp technique in vestibular ganglion neurons of the rat at two postnatal stages (P7-10 and P25-28). In addition, by RT-PCR and immunohistochemistry the identity and distribution of hyperpolarization-activated and cyclic nucleotide-gated channel (HCN) isoforms that generate I_n were investigated. I_n current density was larger in P25-28 than P7-10 rats, increasing 410% for small cells (<30 pF) and 200% for larger cells (>30 pF). The half-maximum activation voltage (V_(1/2)) of I_n was -102 mV in P7-10 rats and in P25-28 rats shifted 7 mV toward positive voltages. At both ages, intracellular cAMP increased I_n current density, decreased its activation time constant (t), and resulted in a rightward shift of V_(1/2) by 9 mV. Perfusion of 8-BrcAMP increased I_n amplitude and speed up its activation kinetics. I_n was blocked by Cs~+, zatebradine, and ZD7288. As expected, these drugs also reduced the voltage sag caused with hyperpolarizing pulses and prevented the postpulse action potential generation without changes in the resting potential. RT-PCR analysis showed that HCN1 and HCN2 subunits were predominantly amplified in vestibular ganglia and end organs and HCN3 and HCN4 to a lesser extent. Immunohistochemistry showed that the four HCN subunits were differentially expressed (HCN1 > HCN2 > HCN3 > HCN4) in ganglion slices and in cultured neurons at both P7-10 and P25-28 stages. Developmental changes shifted V_(1/2) of I_n closer to the resting membrane potential, increasing its functional role. Modulation of I_n by cAMP-mediated signaling pathway constitutes a potentially relevant control mechanism for the modulation of afferent neuron discharge.
机译：通过全细胞膜片钳技术研究了大鼠两个出生后阶段（P7-10和P25-28）前庭神经节神经元的超极化激活电流（I_n）的性质，发育调控和cAMP调节。此外，通过RT-PCR和免疫组织化学，研究了产生I_n的超极化激活和环状核苷酸门控通道（HCN）亚型的身份和分布。 P25-28中的I_n电流密度大于P7-10大鼠，小细胞（<30 pF）增加410％，大细胞（> 30 pF）增加200％。在P7-10大鼠中，I_n的半最大激活电压（V_（1/2））为-102 mV，在P25-28大鼠中，I_n的半最大激活电压向正电压偏移了7 mV。在两个年龄段，细胞内cAMP都会增加I_n电流密度，降低其激活时间常数（t），并导致V_（1/2）向右移动9 mV。灌注8-BrcAMP会增加I_n振幅并加快其激活动力学。 I_n被Cs〜+，zatebradine和ZD7288阻止。不出所料，这些药物还减少了由超极化脉冲引起的电压骤降，并防止了后脉冲动作电位的产生而不会改变静息电位。 RT-PCR分析显示，HCN1和HCN2亚基主要在前庭神经节和终末器官以及HCN3和HCN4中扩增。免疫组织化学显示，神经节切片和神经元在P7-10和P25-28阶段，四个HCN亚基差异表达（HCN1> HCN2> HCN3> HCN4）。发育变化将I_n的V_（1/2）移至更接近静止膜电位，从而增强了其功能性作用。通过cAMP介导的信号通路对I_n的调节构成了传入神经元放电的调节的潜在相关控制机制。

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