层粘连蛋白及基质金属蛋白酶-9在大鼠局灶性脑缺血梗死区周围的表达及意义

Expression of Laminin and Matrix Metalloproteinase-9 around the Infarct Area Following Focal Ischemia in Rat Brains and Its Significance

目的观察局灶性脑缺血梗死区周围层粘连蛋白(Laminin)及基质金属蛋白酶(MMP)-9表达,探讨其在脑缺血再灌注损伤发病机制中的作用。方法将45只体重250～300 g、4个月龄的Sprague Dawley(SD)雄性大鼠随机分为假手术(Sham)组与局灶性缺血再灌注(MCAO)组。MCAO组又分6、24、72 h及7 d组,每组各9只。光学显微镜下观察脑组织病理改变,免疫组织化学染色检测各组Laminin及MMP-9的表达情况。结果再灌注后6 h,即有MMP-9表达明显增高,表达高峰出现在再灌注后24 h,3 d时有所下降,至7 d时仍明显高于基础水平(P<0.01)。Laminin的表达于再灌注6 h开始降低,24 h降至最低,3 d后开始缓慢回升。结论脑缺血再灌注后,病变区MMP-9与Laminin表达变化可反映脑血管壁受损状况,并与脑缺血损伤及修复过程有关。

Objective To investigate the expression of matrix metalloproteinase-9 （MMP-9） and laminin around the infarct area following focal ischemia in adult rat brains. Methods Using a random number table, 45 four-month-old male SD rats were divided into two groups： sham operation group and middle cerebral artery occlusion （MCAO） group. The model of acute reperfusion injury after cerebral ischemia in rats was made by MCAO. The MCAO group was further divided into four subgroups according to different durations of reperfusion, including 6 hours, 24 hours, 3 days and 7 days. The expression of MMP-9 and Laminin was detected using an immunohistochemical approach. Results The number of MMP-9 immunoreactive cells at hour 6 after reperfusion in ischemic side in MCAO group started to increase markedly and presented significant difference compared with the sham group. It peaked at hour 24 and then decreased gradually at day 3 but was still higher than that of the sham group at day 7 after reperfusion. The expression of laminin began to decrease at hour 6 and reached to the minimum. It started to increase slowly 3 days later. Conclusion In the cerebral ischemia- reperfusion injury, the change of MMP-9 and laminin expressions may reflect the impaired cerebral blood wall and has close relationship with the cerebral ischemic injury and repair process.