Therapeutic effect of dexamethasone and mannitol on global brain ischemia-reperfusion injury in rats

To determine the effect of dexamethasone and mannitol on reperfusion injury after global brain ischemia in rats.Forty-two Wistar rats were randomly divided into six groups: normal group (n = 5), normal rats without any surgical operation; sham operative group (n = 6), the rat bilateral vertebral arteries were electrocauterized; ischemia group (n = 7), bilateral vertebral arteries were electrocauterized, and both carotid arteries were occluded temporarily by atraumatic artery clasp for 10 minutes; dexamethasone group (n = 8), intraperitoneal dose of dexamethasone of 10 mg.kg-1 (body weight) was received immediately after vessel occlusion (VO), twice a day; mannitol group (n = 8), intravenous dose of 20% mannitol of 10 ml.kg-1 was received 4 hours after VO, three times a day; dexamethasone combined with mannitol group (n = 8), both intraperitoneal dexamethasone of 10 mg.kg-1, twice a day, and intravenous 20% mannitol of 10 ml.kg-1, three times a day were administered. All rats were sacrificed and brains were removed after 72 hours. A 3 mm thick coronal brain was sliced from temporal lobe for histopathological examination. Ischemic neurons and neuron density in hippocampal CA1 region were measured with paraffin sections stained by HE methods. Apoptosis of cells was observed by TUNEL method. The rest of the brain was used to measure water contents by means of wet-dry method.All drug-treated groups could effectively reduce brain edema. Dexamethasone exacerbated ischemic neuronal injury but dexamethasone combined with mannitol was the most effective treatment for brain ischemia injury compared with other groups.Dexamethasone aggravates brain ischemic-reperfusion injury, mannitol is effective for reducing brain ischemia-reperfusion injury, and application of the combined agents is the most effective treatment.PubMed03303-63