弥漫性脑损伤中基质金属蛋白酶的动态变化及其意义

Dynamic changes and significance of matrix metalloproteinase(MMPs) in rats with diffuse brain injury

目的探寻弥漫性脑损伤后基质金属蛋白酶(MMP)表达的动态变化及其与细胞凋亡的关系。方法84只大鼠随机分为3组:空白组(不做脑室注射)、盐水组(脑室注射生理盐水)和实验组(脑室注射抑制剂),分别在伤后30 min、1、3、6 h、1、3和7 d处死大鼠,断头取脑。用TUNEL法检测细胞凋亡,明胶酶谱法检测MMP表达。结果酶原型MMP-9在伤后30 min就有表达,1 d时达到峰值,而后下降,7 d后未回落到伤后30 min水平;酶原型MMP-2,呈双峰形式,30 min就有表达,6 h到达第1个高峰,然后下降,3 d时再次升高到达第2个峰值,7 d后小幅回落;活性型MMP-2的表达呈逐渐上升形式,30 min就有表达,7 d时达到高峰。MMP抑制剂对各种MMP表达的作用各不相同,它可上调酶原型MMP-9的表达(P<0.01),下调活性型MMP-2的表达(P<0.01),对酶原型MMP-2的表达无影响。MMP抑制剂在各个时间点上,均可减少细胞凋亡(P<0.01)。结论弥漫性脑损伤后,不同的MMP有不同的表达形式:酶原型MMP-9呈单峰型,酶原型MMP-2呈双峰型,活性型MMP-2呈上升型。MMP抑制剂能上调酶原型MMP-9的表达,抑制活性型MMP-2的表达,可降低细胞凋亡,具有一定的神经保护作用。

Objective To explore the expression of matrix metalloproteinase （MMP） at different time points after diffuse brain injury in rats and the relationship between MMP and apoptosis. Methods Eighty-four rats were divided into three groups of blank （non-intraventricular injection）, control （ normal saline intraventricular injection） and inhibitor （ CTT intraventricular injection）. The rats were killed at 30 rain, 1,3, 6 h, and on the 1st, 3rd and 7th day after injury. Apoptosis was checked using TUNEL method. MMPs were evaluated by gelatin-zymography. Results Pro-MMP-9 expression peaked on the 1st day after injury, pro-MMP-2 expression showed double peaks of one at 6 h and the other on the 3rd day after injury. Activated MMP-2 expression was detected at 30 min after injury and peaked on the 7 day after injury. CTT（an inhibitor of MMP） upregulated pro-IVLMP-9 expression （P〈0. 01）, but downregulated the expression of activated MMP-2 （P〈0.01） without any significant effect on pro-MMP-2 expression. Compared with control group, CTT decreased the apoptosis （P〈0.01）. Conclusion MMPs have different expression patterns in rats after diffuse brain injury, pro-MMP-9 showed one-peak pattern, pro-MMP-2 showed double-peak pattern, and aetivated-MMP-2 increased consecutively from 30 mim to the 7th day after injury. Inhibitor of MMPs upregulated expression of pro-MMP-9 and down-regulated expression of activated-MMP-2, which has neuro-protective efficacy through reducing apoptosis.