Objective: To explore the role of β2-nicotinic acetylcholine receptor (β2-nAChR) in the development of γ- aminobutyric acid A type receptors (GABAA-Rs) in hippocampal CA1 and CA3 pyramidal neurons of mice.
Methods: The hippocampal CA1 and CA3 pyramidal neurons were acutely isolated from β2-nAChR gene knockout (β2-KO group) mice. GABA currents in CA1 and CA3 pyramidal neurons were induced with the selective GABAA-R agonist muscimol and recorded using perforated patch-clamp recording technique. The GABA currents of CA1 and CA3 pyramidal neurons were tested for their equilibrium potentials (EMuss) and kinetic parameters and were compared with the measurements in wild-type mice (WT group).
Results: The mean EMus of CA1 neurons (n=7) of β2-KO mice (n=4) was -31.7±3.5 mV, showing an obvious depolarizing shift compared with the WT mice (P < 0.05); the mean EMus of CA3 neurons (n=4) was -16.1±4.6 mV, also showing a depolarizing shift (P < 0.01). The difference in the EMuss between CA3 and CA1 neurons in β2-KO mice, but not in WT mice, was significant (P < 0.05). The GABAA-R desensitization was significantly slowed down in both CA1 and CA3 neurons of β2-KO mice, with decay time of 2.2±0.2 s and 3.2±0.1 s, respectively, significantly longer than those in WT mice (1.6±0.1 s and 2.3±0.1 s, respectively; P < 0.05).
Conclusions: β2-containing nAChRs may promote the functional maturation of GABAA-R in CA1 and CA3 pyramidal cells in mouse hippocampus.
目的: 探讨β2-烟碱型乙酰胆碱受体（β2-nAChR）在海马CA1和CA3锥体神经元的A型γ-氨基丁酸受体（GABAA-R）发育中的作用。
方法: 应用β2-nAChR基因敲除小鼠（β2-KO组）制备急性分离的海马CA1和CA3锥体神经元，应用穿孔膜片钳记录技术记录GABAA-R选择性激动剂蝇蕈醇在CA1和CA3锥体神经元诱导的GABA电流，测试其平衡电位（EMus）和动力学指标，并与野生型小鼠（WT组）进行比较。
结果: β2-KO组小鼠（n=4）CA1锥体神经元（n=7）的EMus为-31.7±3.5 mV，与WT组相比向去极化偏移（P < 0.05）；CA3锥体神经元（n=4）的EMus为-16.1±4.6 mV，同样较WT组偏向去极化方向（P < 0.01）；与WT组小鼠不同，β2- KO组小鼠CA3和CA1神经元的EMus差异有统计学意义（P < 0.05）。β2-KO组小鼠CA1和CA3神经元上都显示GABAA-R的失敏显著减慢，衰减时间分别为2.2±0.2 s、3.2±0.1 s（WT组为1.6±0.1 s、2.3±0.1 s，P < 0.05或P < 0.01）。
结论: 含β2的nAChR可能参与促进小鼠海马CA1和CA3锥体细胞中GABAA-R的功能成熟。
Keywords: equilibrium potential of muscimol-induced currents; gene knockout; hippocampus; kinetic indexes; β2-nicotinic acetylcholine receptors; γ-aminobutyric acid A type receptors.