p38信号通路对大鼠脑创伤后MMP-9的表达及脑水肿形成的影响

Blocking p38 signal pathway lowers MMP-9 expression and reduces brain edema in rats with traumatic brain injury

目的观察并探讨阻断p38通路激活对大鼠脑创伤后基质金属蛋白酶-9(MMP-9)的表达变化及脑水肿形成的影响及意义。方法健康成年雄性SD大鼠130只,随机分为正常组10只,对照组40只:假手术处理;脑创伤组40只:制作改进式Feeney's脑创伤模型;p38抑制组40只:脑创伤前15 min股静脉注射p38抑制剂(SB203580,400μg/kg)。分别在脑创伤后2 h、2 d时断头取脑,采用RT-PCR法和Western blotting法检测脑组织P38磷酸化水平及MMP-9 mRNA及蛋白表达水平,Evans Blue法测定血脑屏障通透性变化;干湿比重法测定脑组织含水量。结果(1)与对照组相比,脑创伤组磷酸化p38的水平在伤后2 h明显上升;MMP-9 mRNA和蛋白在脑创伤后2 h未见明显差异(P>0.05),但2 d时表达均显著增高(P<0.01)。与脑创伤组相比,p38抑制组伤后2 h时p38磷酸化水平明显降低(P<0.01),MMP-9 mRNA和蛋白在创伤后2 d时的高表达也均有明显下降(P<0.05);(2)与对照组比较,脑创伤组血脑屏障通透性在创伤后2 h明显增加(P<0.05),2 d时出现继续升高(P<0.01);脑含水量在创伤后2 h无明显变化(P>0.05),在2 d时显著增加(P<0.01)。与脑创伤组相比,p38抑制组血脑屏障通透性及脑含水量在创伤后均有明显降低(P<0.05)。结论阻断p38通路激活可下调大鼠脑创伤后MMP-9高表达,减轻血脑屏障破坏及创伤性脑水肿,提示p38信号通路可通过调节MMP-9的表达变化在创伤性脑水肿中发挥重要作用。

Objective To explore the role of p38 signal pathway in regulating matrix metalloproteinase-9 （MMP-9） expression and brain edema formation in a rat model of traumatic brain injury （TBI）. Methods A total of 130 adult male Sprague Dawley rats were randomly divided into 4 groups, namely the normal group （n=lO）, sham-operated group （n=40）, TBI （induced by Feeney free falling methods） group （n=40）, and SB group with intraperitoneal SB203580 treatment （10 μmol/L） 15 min before TBI （n=40）. The rats were sacrificed 2 h and 2 days after TBI. The expressions of p38, p-p38, and MMP-9 mRNA and protein were detected by RT-PCR and Western blotting. The blood brain barrier permeability was detected by Evans Blue （EB） test, and the brain water content （BWC） was determined using a gravimetric technique. Results The expression of p-p38 protein increased markedly 2 h after TBI （P〈0.05）, and was suppressed by SB203580 treatment （P〈0.05）. MMP-9 mRNA and protein showed no obvious increase at 2 h after TBL but significantly increased at 2 days as compared with those in the sham-operated group （P〈0.05）. MMP-9 mRNA and protein were much lower in SB group than in TBI group 2 days after TBI （P〈0.05）. The blood brain barrier permeability significantly increased 2 h after TBI （P〈0.05） and kept increasing until 2 days （P〈0.05）, but was reduced significantly by SB203580 （P〈0.05）. BWC increased obviously 2 days after TBI （P〈0.05） and was lessened by SB203580 （P〈0.05）. Conclusion Blocking p38 signal pathway can attenuate MMP-9 upregulation and brain edema after TBI, suggesting the important role of p38 in regulating MMP-9 expression to affect traumatic brain edema.