Matrix metalloproteinases and TIMPs are associated with blood-brain barrier opening after reperfusion in rat brain.
OBJECTIVE
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Rosenberg
G A
GA
Departments of Neurology, Cell Biology and Physiology, and Neuroscience, University of New Mexico, Albuquerque, NM 87131, USA grosen@unm.edu
Estrada
E Y
EY
Dencoff
J E
JE
D000818:Animals; D001593:Benzyl Compounds; D001812:Blood-Brain Barrier / Q000502:physiology*; D001834:Body Water / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002199:Capillary Permeability / Q000502:physiology; D017364:Collagenases / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004338:Drug Combinations; D004573:Electrolytes / Q000378:metabolism; D018093:Gelatinases / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008666:Metalloendopeptidases / Q000378:metabolism*; D010431:Pentoxifylline / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015424:Reperfusion; D013386:Succinates; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*
C101468:BB 1101; D001593:Benzyl Compounds; D004338:Drug Combinations; D004573:Electrolytes; D011480:Protease Inhibitors; D013386:Succinates; D019715:Tissue Inhibitor of Metalloproteinase-1; D019714:Tissue Inhibitor of Metalloproteinases; D019716:Tissue Inhibitor of Metalloproteinase-2; D003907:Dexamethasone; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D010431:Pentoxifylline