Effect of neuropeptideY on the T-type Ca^<2+> channel current

T型Ca^<2+>通道在调节神经元和非神经元可兴奋细胞的兴奋性中起着重要作用。神经肽Y（neuropeptideY，NPY）是中枢和外周神经系统中表达最丰富的神经肽之一，其分布与T型Ca^<2+>通道的分布密切相关，提示两者之间存在功能性相互作用。在本研究的前半部分，我使用了未分化的NG 108 -15细胞，其中T型Ca^<2+>通道电流的表达得到了证实。我用Ba^<2+>作为电荷载体的全细胞膜片钳技术发现，低剂量的NPY显著增加了T型Ca^<2 +>通道电流。NPY治疗使I-V关系负性改变。用NPY受体亚型选择性激动剂/拮抗剂的实验表明，Y_1和Y_2受体都参与电流的增加。RT-PCR检测结果显示，Y_1和Y_2受体mRNA均有表达。在后半部分，为了研究NG 108-15细胞在脑制备中所表现出的功能相互作用，我建立了海马脑片的培养体系，并报道了表达这些蛋白的细胞。我用切片膜片钳技术检测了CA 1锥体神经元表达的电压依赖性通道电流。NPY对电压依赖性通道电流的影响还需进一步研究。

T-type Ca^<2+> channel plays pivotal roles in regulating the excitability of the neurons and non-neuronal excitable cells. The neuropeptideY (NPY) is one of the most abundantly expressed neuropeptides in the central and peripheral nervous systems, and its distribution correlates well with that of T-type Ca^<2+> channel, suggesting a functional interaction with it. The aim of this study was to investigate the functional interaction. In the former half of this study, I used the undifferentiated NG108-15 cells, in which the expression of the T-type Ca^<2+> channel current was confirmed. I found that low doses of NPY significantly augmented the T-type Ca^<2+> channel current with whole cell patch-clamp technique using Ba^<2+> as the charge carrier. The NPY treatment shifted the I-V relationship negatively. Experiments using NPY receptor subtype-selective agonist/antagonists revealed that both Y_1 and Y_2 receptors additively involved in the augmentation of the current. Consistently, RT-PCR analysis showed the expressions of mRNAs for Y_1 and Y_2 receptors. In the later half, to investigate the functional interaction, which was shown in the NG 108-15 cells, in the brain preparation, I set up culture system of hippocampal slice, which was reported to express the proteins. I examined the voltage-dependent channel currents expressed in the CA1 pyramidal neurons with slice patch-clamp technique. Further work is needed to obtain the conclusion of the NPY's effect on the voltage-dependent channel currents.