皮质酮快速抑制PC12细胞乙酰胆碱诱发电流影响及机制探讨

RAPID, NON GENOMIC INHIBITORY EFFECT OF CORTICOSTERONE ON ACETYLCHOLINE INDUCED CURRENT IN PC12 CELLS

目的和方法：本研究采用全细胞膜片箝技术，观察皮质酮（Ｂ）对ＰＣ１２细胞上乙酰胆碱诱发电流（ＩＡＣｈ）的快速作用并初步探讨其可能机制。结果：ＰＣ１２细胞上ＩＡＣｈ是通过烟碱受体（ｎＡＣｈＲ）引起的。箝制电压为－８０ｍＶ时，ＡＣｈ（３０μｍｏｌ／Ｌ）诱发一内向电流；细胞外灌流同时给予ＡＣｈ和Ｂ（１０－５ｍｏｌ／Ｌ）时，Ｂ对ＩＡＣｈ的抑制作用较弱；用Ｂ（１０－５ｍｏｌ／Ｌ）对细胞进行预处理，可提高Ｂ对ＩＡＣｈ峰值的抑制率，作用呈可逆性、浓度依赖性和非电压依赖性；细胞外用ＲＮＡ合成抑制剂放线菌素Ｄ（４×１０－５～４×１０－３ｍｏｌ／Ｌ）或蛋白合成抑制剂放线菌酮（１０－４～１０－３ｍｏｌ／Ｌ）孵育细胞１～２ｈ阻断基因机制，但均不影响Ｂ对ＩＡＣｈ的快速抑制作用。结论：Ｂ对ＰＣ１２细胞上ＩＡＣｈ有快速抑制作用，此作用可能是由非基因组机制介导的。

Aim and Methods: A rapid effect of corticosterone (B) on acetylcholine induced current in PC12 cells and its possible mechanism were investigated by whole cell clamping technique. Results: The acetylcholine induced current (I ACh ) of PC12 cells was proved to be generated through nicotinic ACh receptor by pharmacological identification. ACh (30 μmol/L) induced an inward current at a holding potential (V h) of -80mV; The inhibitory effect of corticosterone (B) on I ACH was weak when extracellular simultaneous application of 10 -5 mol/L B and ACh; Pretreatment of PC12 cells with B augmented the inhibitory effect on peak I ACh , and it was reversible, concentration dependent and voltage independent. The rapid inhibitory effect of B was not affected by pretreating cells with actinomycin D(inhibitor of RNA synthesis, 4×10 -5 ～4×10 -3 mol/L) or cycloheximide (inhibitor of protein synthesis 10 -4 ～10 -3 mol/L) for 1～2h. Conclusion:Corticosterone induces rapid inhibitory effect on I ACh in PC12 cells, which is mediated by a nongenomic mechanism.