全脑缺血后PAF和细胞内钙离子的变化及相关机制研究

Study of relationship between platelet-activating factor and synaptosomal cytosolic free calcium in rat hippocampus ischemia-reperfusion

目的 探讨血小板活化因子 (PAF)在缺血性脑损伤中的作用机制。方法 大鼠全脑缺血再灌注后 ,分别应用放免法和 Fura- 2 / AM荧光法测定海马组织中 PAF、突触体游离钙 ([Ca2 + ]i)浓度。结果 缺血 2 0 min后 ,PAF含量显著高于对照组 ,再灌注 2 40 m in时已降至对照组水平 ,再灌注 480 m in后出现迟发性升高。对应 [Ca2 + ]i值随所观察的再灌注时间延长而增加。 Tetrandrine(钙拮抗剂 )能明显降低再灌注 480 min时 PAF和 [Ca2 + ]i水平。结论 全脑缺血再灌注后 ,PAF的异常代谢与 [Ca2 + ]i水平密切关联 ,协同参与了神经细胞损伤的发生及发展。

Objective In order to study the action and significance of platelet activating factor(PAF) on the cerebral ischemia reperfusion damage, the PAF and synaptosomal cytosolic free calcium concentrations([Ca 2+ ]i) in rat hippocampus were observed dynamically.Methods 48 mature Wistar rats were randomly divided into seven groups: Sham operated control group, simple ischemia group, 60 minute, 240 minute, 480 minute, 720 minute reperfusion groups and Tetrandrine treated group. With the 4 vessel occlusion model(4VO), the rats were suffered from ischemia for 20 minutes, then reperfusion was allowed for 60, 240, 480, 720 minutes before decapitation. Sham operated control rats were the same except for the clamping vessels. Radioimmunoassay and fluorescent probe Fura 2 of Ca 2+ indicator were applied to determine the PAF and synaptosomal cytosolic free calcium concentrations in rat hippocampus respectively. Results The PAF levels of simple ischemia group were significantly higher than that of control group(P<0.01),but progressively returned to basal values following 240 minute reperfusion(P>0.05), in addition, 480 minutes reperfusion later ,the PAF concentrations appeard to be delayed elevation (P<0.01). Compared with the control group, the [Ca 2+ ]i showed a progressive increase from 0 minute to 720 minutes after reperfusion. However, pretreatment with Tetrandrine significantly attenuated the increase of the PAF and [Ca 2+ ]i levels at 480min reperfusion. Conclusion It was considered that PAF increases could be closely related to changes of [Ca 2+ ]i, suggest the onset and progress of ischemic neuropathological damages.