三磷酸腺苷引起大鼠三叉神经节胞内钙离子信号转导机制的研究

目的探讨三磷酸腺苷(ATP)对三叉神经痛大鼠感觉神经元内钙离子浓度(Ca2+]i)的影响及其信号转导机制。方法 SD大鼠眶下神经缩窄造成三叉神经痛模型,造模后1周处死大鼠,取出三叉神经节(TG),分离出完整的小直径神经元(﹤600μm2)用于钙离子成像,通过使用荧光染料来标记相关激动剂,检测毒胡萝卜内酯(Tg,1μmol/L)、咖啡因(Caff,20 mmol/L)和ATP(100μmol/L)作用下TG小直径神经元内Ca2+]i变化。结果①在正常外液和无钙外液中,在大鼠TG小直径神经元上分别给予Tg、Caff和ATP均能够引起Ca2+]i不同程度升高;②在无钙外液中,ATP引起的TG神经元Ca2+]i升高可被Tg可逆性地抑制(n=8,P<0.01);③在无钙外液中,ATP引起的TG神经元Ca2+]i升高可被P2受体阻断剂苏拉明(suramin,100μmol/L)明显抑制;④在正常外液中,Tg引起TG神经元Ca2+]i升高,当升高达到最大后再次给予ATP,仍然能引起Ca2+]i进一步升高。结论在大鼠TG神经元中同时存在IP3敏感钙库和ryanodine敏感钙库。ATP可通过两种途径引起细胞内Ca2+]i升高,一种途径是激动P2Y受体引起IP3敏感钙库的Ca2+释放,另一种途径是激动P2X受体引起细胞外Ca2+内流。在无钙外液中,ATP引起的TG神经元Ca2+]i升高是通过IP3敏感钙库释放引起的。

ATP-induced intracellular calcium signal transduction mechanism in the rat trigeminale ganglion

Objective To investigate the effect of ATP on intracellular calcium concentration(i)in trigeminal ganglion(TG) neurons and the signal transduction mechanism in trigeminal neuralgia rat.Methods To build the trigeminal neuralgia models and take out of the TG.In acutely isolated TG neurons,calcium imaging technique was applied to monitor the change of i in TG small diameter neurons after application of thapsigargin(1 μmol/L),caffeine(1 μmol/L) and ATP(100 μmol/L).Results ① In the small TG neurons of rat,thapsigargin,caffeine and ATP could induce elevation of i in normal and Ca2+-free extracellular solution.② However,on the condition of removing extracellular Ca2+,the ATP-induced elevation of i was reversibly inhibited by thapsigargin(n=8,P<0.01).③ In Ca2+-free extracellular solution,the ATP-induced elevation of i was inhibited obviously by P2 receptor antagonist suramin(100 μmol/L).④ In the normal extracellular solution,after thapsigargin-induced i increased to maximum,ATP could still induce a significant increase of i.Conclusion Both IP3 and ryanodine-sensitivity Ca2+ stores exist in small TG neurons of rat.ATP increases intracellular i through the release in IP3-sensitivity Ca2+ stores which is mediated by the activation of P2Y receptor,and extracellular calcium internal flow via the activation of P2X receptor.On the condition of Ca2+-free,the ATP-induced elevation of i is released from the IP3-sensitivity Ca2+ stores.