峰毒肽Mastoparan诱导大鼠小脑颗粒神经元死亡的机制

Mechanism of mastoparan induced neuronal death in cultured cerebellar granule neurons

目的研究峰毒肽ｍａｓｔｏｐａｒａｎ（ＭＰ）通过改变细胞内钙离子浓度（［Ｃａ２＋］ｉ）诱导大鼠小脑颗粒神经元死亡的机制。方法测定原代培养神经元的存活率；用Ｆｕｒａ－２／ＡＭ荧光比值成像技术测定［Ｃａ２＋］ｉ。结果ＭＰ剂量依赖性地诱导小脑颗粒神经元死亡，并触发［Ｃａ２＋］ｉ升高。移去细胞外钙，或使用电压依赖性Ｃａ２＋通道阻滞剂尼莫地平不能阻断其作用。用ｔｈａｐｓｉｇａｒｇｉｎ预先耗竭１，４，５三磷酸肌醇敏感的胞内Ｃａ２＋库；或用特异性的磷酯酶Ｃ抑制剂Ｕ７３１２２预处理细胞，能显著地抑制ＭＰ的作用。结论ＭＰ可能通过激活ＰＬＣ／ＩＰ３信号传导途径。

AIM To study the mechanisms of neuronal death induced by mastoparan(MP), a wasp venom peptide. METHODS Using Fura 2/AM probe with microspectrofluorimetry ratio imaging system measure intracellular Ca 2+ ([Ca 2+ ] i) in cultured cerebellar granule neurons and neuronal survival was detected by fluorescein diacetate staining. RESULTS MP rapidly induced neuronal death and increase in [Ca 2+ ] i in a concentration dependent manner, The rise in [Ca 2+ ] i induced by MP was maintained in the absence of extracellular calcium and did not blocked by nimodipine, a L type Ca 2+ channel blocker. Depletion of intracellular calcium stores with thapsigargin significatly attenuated the rise in [Ca 2+ ] i and prevented MP-induced neuronal death. Moreover, Pretreatment with phospholipase C(PLC) inhibitor U73122 also significantly inhibited MP induced [Ca 2+ ] i increase and protected against neuronal death. CONCLUSION Mastoparan raises [Ca 2+ ] i by a release of calcium from intracellular calcium stores. The effects of MP on calcium release may activate PLC/IP 3 signal transduction pathway.