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

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。

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

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=10),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 TBI,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.