中华绒螯蟹眼柄MTXO细胞GABA受体通道研究

Study on The GABA Gated Channels in The Neurosecretory Cells of MTXO in The Eyestalks of Eriocheir sinensis

采用全细胞膜片钳技术测定了中华绒螯蟹 (Eriocheirsinensis)眼柄视神经节端髓X器官 (MTXO)三种类型神经内分泌细胞对 0 0 1～ 5mmol/Lγ氨基丁酸 (γ aminobutyricacid ,GABA)的反应 ,并结合选择性拮抗剂和激动剂的使用进行了GABA受体研究 .在电流钳模式下 ,依据不同NernstCl-电位 ,三种类型细胞均对GABA产生去极化或超级化反应 .在电压钳模式下 ,GABA激活Cl-通道电流 (IGABA) .IGABA在灌流GABA后约12 0 0ms内激活 ,80 0ms内达到峰值 ,没有明显的脱敏反应 ,反转电位接近NernstCl-电位 .IGABA幅值呈浓度依赖性 ,激活阈值为 0 0 1mmol/L ,约在 0 5mmol/L达到饱和 .药理学实验结果表明 ,中华绒螯蟹眼柄神经内分泌细胞GABA受体是Cl-通道蛋白 ,对Cl-离子通道阻断剂Picrotoxin和Niflumicacid敏感 ,但是对GABAA 受体拮抗剂Bicuculline和GABAC 受体激动剂cis 4 aminocrotonicacid (CACA)和trans 4 aminocrotonic (TACA)均不敏感 .

The responses to rapid application of gamma-aminobutyric acid (GABA) and the GABA receptor characteristics of MTXO neurosecretory cells in the eyestalks of Chinese mitten-handed crab (Eriocheir sinensis) were examined by whole-cell patch clamp. Under current clamp mode, the depolarization and hyperpolarization were evoked from the three types of neurosecretory cells in response to the GABA (0.1 mmol/L) depending on the Nernst Cl(-) potential. Under voltage clamp mode, the inward Cl(-) channel currents (I(GABA)) were resolved from all three types of neurosecretory cells in response to GABA (0.01similar to5 mmol/L). The GABA currents were activated within 1 200 ms and peaked within 800 ms. No obviously desensitization was observed during GABA application. The dose-response curve showed usual S-shape, with a just-discernible effect at 0.01 mmol/L and near-saturation at 0.5 mmol/L. The GABA currents had reversal potentials that followed Nernst Cl(-) potentials when [Cl(-)] was varied. The pharmacological results revealed that the GABA receptor of the crab neurosecretory cells was sensitive to the Cl(-) channel blockers picrotoxin and niflumic acid (0.5 mmol/L), insensitive to GABA(A) receptor antagonist bicuculline and GABA(C) receptor agonist cis-4-aminocrotonic acid (CACA 1 mmol/L) and trans-4-aminocrotonic (TACA 1 mmol/L).