硫酸镁对大鼠脑缺血及再灌注时细胞外液谷氨酸、葡萄糖和乳酸的影响

目的:探讨Mg2 对大鼠脑缺血和再灌注时细胞外液中谷氨酸、葡萄糖和乳酸的影响.方法:雄性Wistar大鼠12只,随机分为硫酸镁组和生理盐水组,每组6只,线栓法制备局灶性脑缺血再灌注模型,脑缺血前30 min分别给予硫酸镁100mg/kg或生理盐水2 ml腹腔注射;微透析技术每15 min取缺血侧皮层细胞外液1次,观察缺血1 h及再灌注1 h期间脑细胞外液谷氨酸、葡萄糖及乳酸动态变化.结果:硫酸镁组缺血期葡萄糖降低的幅度显著低于生理盐水组(P＜0.05,P＜0.01),再灌注后即恢复正常;缺血早期(0～15 min)及再灌注期乳酸水平也明显低于生理盐水组(P＜0.05,P＜0.01);各时间点谷氨酸浓度均显著低于生理盐水组,硫酸镁组再灌注30min时恢复正常.结论:Mg2 可能通过改善能量代谢,减少乳酸堆积以及降低谷氨酸浓度来实现对脑缺血及再灌注损害的保护作用.

Effects of magnesium sulfate on glutamate and energy metabolites during focal cerebral ischemia and reperfusion in rats

Objective:To study the effect of Mg 2+ on glutamate and energy metabolites during focal cerebral ischemia and reperfusion in rats. Methods: Twelve male Wistar rats were divided into 2 groups(n=6):magnesium sulfate(100 mg/kg, i.p.) group and saline group.Cerebral ischemia was produced by occlusion of middle cerebral artery with a nylon thread for 60 min and followed by 60 min reperfusion.Microdialysis probes were stereotaxically implanted into the cortex; dialysates were collected every 15 min to determine the concentrations of glucose, lactic acid and glutamate. Results: There was a dynamic decrease of glucose and an increase of lactic acid and glutamate during ischemia and reperfusion in saline group.Glucose decreased slightly in magnesium sulfate group during ischemia and recovered to normal rapidly during reperfusion. The lactic acid levels in magnesium sulfate group were lower than that in saline group during early stage of ischemia(0-15 min) and reperfusion.There were significant attenuation in the elevation of glutamate during ischemia and reperfusion when magnesium sulfate was administered and recovered to normal after 30 min of reperfusion. Conclusion: The preservation of cellular energy metabolism,the decrease of lactacidosis and attenuation of glutamate level during ischemia and reperfusion may contribute to the neuroprotective effects of Mg 2+ .