Brain Capillary Tissue Plasminogen Activator in a Diabetes Stroke Model

Background and Purpose Tissue plasminogen activator (TPA) is normally expressed in rat brain capillaries. This study examines the expression of TPA in brain capillaries of diabetic rats in relation to focal ischemic brain injury. Methods Diabetes type 1 was induced by streptozotocin for 7 days. Acute hyperglycemia was induced by 50% dextrose. Expression of TPA in brain capillaries was determined by Western blot and reverse transcription-polymerase chain reaction analyses. Focal stroke was produced by 1 hour of reversible middle cerebral artery occlusion. Physiological variables and cerebral blood flow were monitored during occlusion and within 1 hour of reperfusion. Neurological and neuropathologic examinations were performed after 24 hours of reperfusion. Results All rats developed comparable hyperglycemia (≈15 mmol/L). A complete depletion of TPA protein and 6.5-fold decrease in TPA mRNA were found in brain capillaries of diabetic rats, in contrast to normal TPA capillary levels in hyperglycemic rats. T...