Rosenberg G A, Estrada E Y, Dencoff J E
Departments of Neurology, Cell Biology and Physiology, and Neuroscience, University of New Mexico, Albuquerque, NM 87131, USA
Stroke. 1998 Oct;29(10):2189-95. doi: 10.1161/01.str.29.10.2189.
Reperfusion disrupts cerebral capillaries, causing cerebral edema and hemorrhage. Middle cerebral artery occlusion (MCAO) induces the matrix-degrading metalloproteinases, but their role in capillary injury after reperfusion is unknown. Matrix metalloproteinases (MMPs) and tissue inhibitors to metalloproteinases (TIMPs) modulate capillary permeability. Therefore, we measured blood-brain barrier (BBB) permeability, brain water and electrolytes, MMPs, and TIMPs at multiple times after reperfusion.
Adult rats underwent MCAO for 2 hours by the suture method. Brain uptake of 14C-sucrose was measured from 3 hours to 14 days after reperfusion. Levels of MMPs and TIMPs were measured by zymography and reverse zymography, respectively, in contiguous tissues. Other rats had water and electrolytes measured at 3, 24, or 48 hours after reperfusion. Treatment with a synthetic MMP inhibitor, BB-1101, on BBB permeability and cerebral edema was studied.
Brain sucrose uptake increased after 3 and 48 hours of reperfusion, with maximal opening at 48 hours and return to normal by 14 days. There was a correlation between the levels of gelatinase A at 3 hours and the sucrose uptake (P<0.05). Gelatinase A (MMP-2) was maximally increased at 5 days, and TIMP-2 was highest at 5 days. Gelatinase B and TIMP-1 were maximally elevated at 48 hours. The inhibitor of gelatinase B, TIMP-1, was also increased at 48 hours. Treatment with BB-1101 reduced BBB opening at 3 hours and brain edema at 24 hours, but neither was affected at 48 hours.
The initial opening at 3 hours correlated with gelatinase A levels and was blocked by a synthetic MMP inhibitor. The delayed opening, which was associated with elevated levels of gelatinase B, failed to respond to the MMP inhibitor, suggesting different mechanisms of injury for the biphasic BBB injury.
再灌注会破坏脑毛细血管，导致脑水肿和出血。大脑中动脉闭塞（MCAO）会诱导基质降解金属蛋白酶，但它们在再灌注后毛细血管损伤中的作用尚不清楚。基质金属蛋白酶（MMPs）和金属蛋白酶组织抑制剂（TIMPs）调节毛细血管通透性。因此，我们在再灌注后的多个时间点测量了血脑屏障（BBB）通透性、脑水和电解质、MMPs以及TIMPs。
成年大鼠通过缝线法进行2小时的MCAO。在再灌注后3小时至14天测量大脑对14C-蔗糖的摄取。分别通过酶谱法和反向酶谱法测量相邻组织中MMPs和TIMPs的水平。其他大鼠在再灌注后3、24或48小时测量水和电解质。研究了合成MMP抑制剂BB-1101对BBB通透性和脑水肿的治疗作用。
再灌注3小时和48小时后大脑蔗糖摄取增加，48小时时达到最大开放，14天时恢复正常。3小时时明胶酶A水平与蔗糖摄取之间存在相关性（P<0.05）。明胶酶A（MMP-2）在5天时最大程度增加，TIMP-2在5天时最高。明胶酶B和TIMP-1在48小时时最大程度升高。明胶酶B的抑制剂TIMP-1在48小时时也增加。用BB-1101治疗可在3小时时减少BBB开放，在24小时时减轻脑水肿，但在48小时时两者均未受影响。
3小时时的初始开放与明胶酶A水平相关，并被合成MMP抑制剂阻断。与明胶酶B水平升高相关的延迟开放对MMP抑制剂无反应，提示双相性BBB损伤存在不同的损伤机制。
