[Relationship of changes in basement membrane of microvessels after cerebral ischemia/reperfusion and plasminogen activator system in aged rats].

OBJECTIVE: To study the relationship of changes in basement membrane of cerebral micro-vessels and plasminogen activator system after cerebral ischemia/reperfusion (I/R) injury in aged rats.

METHODS: Middle cerebral artery occlusion (MCAO) was produced by the introduction of a thread. Rats were divided randomly into sham-operation group with young rats (cerebral ischemia 3 hours and I/R 6, 12, 24, 72, 144 hours groups), sham-operation group and I/R groups in aged rats (cerebral ischemia 3 hours and I/R 6, 12, 24, 72, 144 hours groups). Immunohistochemical technique, zymogram analysis, and reverse zymogram analysis were used to study changes in basement membrane structure of cerebral-cortex microvessel, type IV collagen (Col IV) and laminin (LN) contents, and plasminogen activator system in every group.

RESULTS: With the increase of age, Col IV and LN contents of the microvessel basement membrane increased. With prolongation of I/R, the contents of Col IV and LN decreased in both young and aged rats, while the contents of tissue plasminogen activator (t-PA), urokinase plasminogen (u-PA) and plasminogen activator inhibitor (PAI-1) expression increased at the beginning and decreased subsequently. Compared with young groups, Col IV (ischemia 3 hours-I/R 12 hours), LN (ischemia 3 hours-I/R 24 hours), t-PA (I/R 6-24 hours) and u-PA (I/R 12-144 hours) expression levels were higher in aged rats, but PAI-1 (I/R 12 and 24 hours) expression was lower. In addition, changes in PAI-1 contents as determined with reverse zymogram analysis method coincided with its immunoexpression.

CONCLUSION: With the increase of age, alterations in constituents of cerebro-microvessel basement membrane (Col IV and LN) increased. Injury to cerebro-microvessel basement membrane resulted in more serious changes in aged rats compared with the young rats. Changes in cerebro-microvessel basement membrane after I/R injury in the aged SD rats is related to change in plasminogen activator system.