THE TEMPORAL PROFILES OF ICAM-1 PROTEIN AND MESSENGER-RNA EXPRESSION AFTER TRANSIENT MCA OCCLUSION IN THE RAT

Leukocytes may contribute to ischemic cell damage. ICAM-1 expression o n endothelial cells facilitates the migration of leukocytes into tissu e. Therefore, we measured the temporal profiles of ICAM-1 mRNA and pro tein in rat brain after transient (1 or 2 h) of middle cerebral artery (MCA) occlusion. Male Wistar rats (n = 86) were subjected to 1 or 2 h MCA of occlusion, or 2 h of MCA occlusion followed by reperfusion for a variety of durations ranging from 1 h to 1 week. 10 additional cont rol animals were employed. ICAM-1 mRNA and protein were measured durin g ischemia and reperfusion, and immunohistochemical methods were used to identify specific cell types expressing ICAM-1. ICAM-1 mRNA was det ected 1 h after the onset of ischemia, mRNA maximized at 10 h of reper fusion and persisted out to 1 week of reperfusion. ICAM-1 significantl y increased in microvascular endothelial cells at 2 h of reperfusion, maximized at 46 h and persisted out to 1 week of reperfusion (P < 0.05 ). ICAM-1 mRNA and protein are present in ischemic brain early after t he onset of ischemia and reperfusion, respectively. These data provide support for the role of ICAM-1 in mediating leukocyte-endothelial adh esion after transient MCA occlusion in the rat.