Role of transient receptor potential channels in cholecystokinin-induced activation of cultured vagal afferent neurons.
Role of transient receptor potential channels in cholecystokinin-induced activation of cultured vagal afferent neurons.
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DOI：
10.1210/en.2010-0504
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发表时间：
2010-11
期刊：
影响因子：
4.8
通讯作者：
Huan Zhao;S. Simasko
中科院分区：
文献类型：
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作者：
Huan Zhao;S. Simasko
CCK是一种内源性脑肠肽，在食物摄入后释放，通过激活迷走神经促进饱足过程。在体外，CCK增加迷走神经传入神经元亚群的胞浆钙浓度并产生膜去极化。然而，调节这些效应的具体机制和离子电导仍不清楚。在这项研究中，我们使用钙成像、电生理测量和单细胞PCR分析培养的迷走神经传入神经元来直接解决这个问题。电压依赖性钙通道(VDCC)阻滞剂的鸡尾酒未能阻断CCK诱导的钙反应。此外，SKF96365，一种阻断VDCC和C家族瞬时受体电位(Trp)通道的化合物，也未能阻止对CCK的反应。综上所述，这些结果表明，CCK诱导的钙内流不是在膜去极化之后发生的。TRPV家族的抑制剂Ru红和TRPA1可阻断CCK和CCK诱导的钙升高的去极化反应，但对KCl2诱导的钙反应无影响。分别用SB366791和HC030031选择性阻断TRPV1和TRPA1通道对CCK诱导的反应影响不大。应用2-氨基乙氧基二苯硼酸酯，一种选择性TRPV通道的激活剂，但几个TRPC通道的阻断剂，要么没有作用，要么增强了对CCK的反应。此外，聚合酶链式反应实验的结果显示，TRPV2-5在表达CCK1受体的神经元中显著聚集。这些观察结果表明，CCK引起的迷走神经传入神经元胞浆钙升高和膜去极化可能是由TRPV通道(不包括TRPV1)介导的。
Cholecystokinin (CCK), an endogenous brain-gut peptide, is released after food intake and promotes the process of satiation via activation of the vagus nerve. In vitro, CCK increases cytosolic calcium concentrations and produces membrane depolarization in a subpopulation of vagal afferent neurons. However, the specific mechanisms and ionic conductances that mediate these effects remain unclear. In this study we used calcium imaging, electrophysiological measurements, and single cell PCR analysis on cultured vagal afferent neurons to address this issue directly. A cocktail of blockers of voltage-dependent calcium channels (VDCC) failed to block CCK-induced calcium responses. In addition, SKF96365, a compound that blocks both VDCC and the C family of transient receptor potential (TRP) channels, also failed to prevent responses to CCK. Together these results suggest that CCK-induced calcium influx is not subsequent to the membrane depolarization. Ruthenium red, an inhibitor of the TRPV family and TRPA1, blocked both depolarizing responses to CCK and CCK-induced calcium increases, but had no effect on the KCl-induced calcium response. Selective block of TRPV1 and TRPA1 channels with SB366791 and HC030031, respectively, had minor effects on the CCK-induced response. Application of 2-aminoethoxydiphenyl borate, an activator of select TRPV channels but a blocker of several TRPC channels, either had no effect or enhanced the responses to CCK. Further, results from PCR experiments revealed a significant clustering of TRPV2-5 in neurons expressing CCK1 receptors. These observations demonstrate that CCK-induced increases in cytosolic calcium and membrane depolarization of vagal afferent neurons are likely mediated by TRPV channels, excluding TRPV1.