Temporal profile of tissue plasminogen activator (tPA) and inhibitor expression after transient focal cerebral ischemia.

Altered tPA expression may influence the fate of neurons after cerebral ischemia. We determined the changes in tPA and plasminogen activator inhibitor (PAI-1) expression in adult rat brain after transient middle cerebral artery (MCA) occlusion. Immunohistology revealed tPA staining in ipsilateral but not contralateral cortex and striatum 6 h after occlusion. This pattern was maintained at 24 h. Staining data was supported by Western blot data which showed no tPA protein in contralateral cortex at 3 h but abundant protein in ipsilateral cortex which increased further at 6 h and 24 h. In contrast there was prominent PAI-1 immunostaining and protein expression in control tissue after MCA occlusion but it diminished progressively at 3, 6 and 24 h in the lesioned cortex.