过表达KCNIP1蛋白对原代培养海马神经元兴奋性的影响

Effect of Kv channel-interacting protein 1 over-expression on excitability of primary cultured hippocampal neurons

目的 探讨过表达钾离子通道相互作用蛋白I（KCNIP1）对原代培养海马神经元A型钾电流及神经元兴奋性的影响。方法 构建增强型绿色荧光蛋白质粒DNA（pEGFP-KCNIP1），利用脂质体方法转染体外原代培养海马神经元，采用全细胞膜片钳技术记录转染后神经元的钾电流及神经元动作电位发放情况。对照组转染未携带目的基因的质粒载体pEGFP。结果 pEGFP-KCNIP1质粒转染神经元可导致KCNIP1的表达增高。KCNIP1的过表达导致海马神经元瞬时外向钾电流较对照组显著增加[分别为（0．96±0．17）nA、（0．72±0．09）nA]，差异有统计学意义（P〈0．05）；对稳态外向型钾电流无显著影响。与对照组比较过表达KCNIPl的神经元诱发动作电位的发放频率降低，阈下电位反应性降低，膜电阻增加，差异具有统计学意义（P〈0．05）。结论 KCNIPl表达上升后可通过增加瞬时外向钾电流降低神经元的兴奋性。

Objective To investigate the effect of Kv channel-interacting protein 1 （KCNIP1） over-expression on K^＋ currents and neuronal excitability in primary cultured hippocampal neurons. Methods Enhanced green fluorescent protein plasmids carried KCNIP1 （pEGFP-KCNIP1） were established; empty pEGFP vectors were used as controls; primary cultured hippocampal neurons were transfected with pEGFP-KCNIP1 and control vectors. Whole-cell patch clamp technique was used for electrophysiological recording. Results The cultured neurons transfected with pEGFP-KCNIP1 led to KCNIP1 over-expression. The amplitudes of A-type K＋ currents in the KCNIPl-overexpress neurons were significantly higher than that in the control group （[0.96±0.17] nA vs. [0.72±0.09] hA, P〈0.05）, while no significant difference was found between the component of steady-state outwards K＋ currents and controls. Current clamp analysis revealed significantly decreased frequency of evoked discharges and subthreshold membrane potential oscillations, and statistically increased membrane resistance of the hippocampal neurons in the group of KCNIP1 over-expression as compared with those in the controls （P〈0.05）. Conclusion Over-expression of KCNIP1 could inhibit neuronal discharges possibly via its potentiation on A-type K^＋ currents.