大鼠弥漫性脑损伤后脑组织中MMP-9的表达与神经元损伤

目的探讨大鼠弥漫性脑损伤后基质金属蛋白酶-9（MMP-9）在脑组织中的表达与神经元损伤的关系。方法荧光实时定量RT—PCR和免疫组化分别测定大鼠弥漫性脑损伤后MMP-9 mRN和MMP-9在脑组织中的表达。光镜和电镜观察神经元的变化。结果外伤后3h大鼠脑组织中MMP-9的阳性表达率开始升高，72h达高峰（50．35％±7．27％），伤后6h～7d各组均明显高于假手术对照组（P〈0．05）；随后开始下降，14d降至对照组水平。MMP-9 mRNA于伤后1h表达水平开始升高，72h达最高（20．56±1．29），伤后12h～7d时明显高于假手术对照组（P〈0．01）；随后开始下降，14d降至对照组水平。光镜及电镜下均可见弥漫性神经元变性和坏死，伤后72h损伤表现最为严重。结论本研究提示大鼠弥漫性脑损伤后MMP-9表达升高并可能参与了外伤后炎症反应和神经元损伤的病理过程。

Expressions of Matrix Metalloproteinase-9 in the Injuried Cerebral Tissues and Damage to Neurons lifter Diffuse Brain Injury in Rats

Objective To explore the relationship between the expression of matrix metalloproteinase-9 （MMP-9） in the cerebral tissues and damage to neurons after diffuse brain injury in rats. Methods The expressions of MMP-9 and MMP-9 mRNA in the injured brain tissues of rats were determined respectively by immunohistochemical techniques and real-time quantitative RT-PCR 1, 3, 6, 12, 24, 48, 72, 168 and 336 hours after the diffuse brain injury. The changes in the histology and uhrastructure of the injured neurons were observed by light and electron microscopes in all the groups. Results The positive rate of expression of MMP-9 started increasing 3 hours after the diffuse brain injury and peaked 72 hours （50.35%±7.27%） after the injury. The expression level of MMP-9 mRNA started increasing 1 hour after the injury and peaked 72 hours after the injury. The positive rates of MMP-9 expression 12, 24, 48, 72 and 168 hours after the injury were significandy higher than those in the sham operation group （P〈0.05）. The levels of MMP-9 mRNA expression 12, 24, 48, 72 and 168 hours after the injury were significantly higher than those in the sham operation group （P〈0.01）.The degeneration, edema and necrosis of neurons were observed in the injured cerebral tissues under light microscope and electron microscope and they were most severe 72 hours after the injury. Conclusion It is suggested that the increase in the expression of MMP-9 in the cerebral tissues may take part in the pathological process of inflammatory reaction and damage to neurons after the diffuse brain injury.