CCK—8翻转k-受体激动剂U50488H对急性分离大鼠背根神经节神经元上钙通道的抑制效应

CCK-8 REVERSES THE INHIBITORY EFFECT OF k-OPIOID RECEPTOR AGONIST U50488H ON CALCIUM CURRENT IN RAT DORSAL ROOT GANGLION NEURON

实验以急性分离的大鼠背根神经节（ＤＲＧ）神经元为标本，用全细胞膜片钳（ｗｈｏｌｅ—ｃｅｌｌｐａｔｃｈ－ｃｌａｍｐ）方法记录钙通道电流，观察分析特异性。受体激动剂Ｕ５０４８８Ｈ对电压依赖性钙通道电流的作用，和ＣＣＫ—８对Ｕ５０４８８Ｈ作用的影响，及其受体机制、结果表明，Ｕ５０４８８可明显抑制钙通道电流，其抑制作用可被。受体桔抗剂Ｎｏｒ—ＢＮ１或ＣＣＫ—８所翻转，而ＣＣＫ－８的作用又可被ＣＣＫ—８受体拮抗剂Ｌ３６５，２６０所对抗。但ＣＣＫ—８本身对钙通道电流并无增强作用，反有轻微的抑制作用。由此得出结论。ＣＣＫ－８可经ＣＣＫ—８受体对抗Ｋ受体介导的对钙通道电流的抑制作用。

Whole-cell patch-clamp experiments were performed on acutely dissociated rat dorsal root ganglion (DRG) neurons. The effect of a highly selective k-opioid agonist U40488H on viotage-gated calcium channel current, the interaction between CCK-8 and U50488H and their mechanisms at receptor level in single cell were studied. The results indicated that U50488H could obviously inhibit calcium current of DRG neurons, and its inhihitory effect could be reversed by k-receptor antagonist Nor-BNI or CCK-8. This reverse effect of CCK-8 can be antagonized by CCK-8 receptor antagonist L365, 260. CCK-8 itself had no enhancing but slightly inhibitory effect on calcim current .It can be concluded that CCK-8 can antagonize the inhibitory effect of k-receptor on voltage-gated calcium current through CCK-8 receptor